JP2025101674A - Golf Club Head - Google Patents

Abstract

To provide a head with excellent repulsion performance at a hitting point position adjusted in the vertical direction.
[Solution] The head 4 includes a face portion 10 having a striking surface 10a. The face main portion 20 of the face portion 10 includes a central portion 22 including a face center Fc, a transition portion 24 on the outside of the central portion 22, and a peripheral portion 26 on the outside of the transition portion 24. The peripheral portion 26 includes a first peripheral portion 261 formed on each of the toe side and the heel side, and a second peripheral portion 262 formed on each of the crown side and the sole side. The transition portion 24 includes a first transition portion 241 located between the central portion 22 and the first peripheral portion 261, and a second transition portion 242 located between the central portion 22 and the second peripheral portion 262. The central portion 22 has a central constant thickness tc and a surface area of 100 ^mm2 or more. The thickness of the first peripheral portion 261 is greater than the central constant thickness tc. The thickness of the second peripheral portion 262 is less than the central constant thickness tc.
[Selected Figure] Figure 4

Description

The present invention relates to a golf club head.

In order to improve repulsion performance, various golf club heads have been proposed, for example, as shown in JP 2021-132995 A, JP 2022-108598 A, and JP 2022-120289 A.

JP 2021-132995 A JP 2022-108598 A JP 2022-120289 A

Golf club heads that are highly tolerant of mishits are becoming known. In these types of golf club heads, the face thickness distribution is set so that the loss in flight distance is small even when the ball is struck at a position that is different from the ideal impact point on the face (for example, the face center, and so forth).

On the other hand, a golf club head with high tolerance is of little benefit in improving the flight distance of a shot by a professional or advanced golfer who has a high probability of hitting the ball at the ideal impact point. Furthermore, when professional or advanced golfers tee up and hit the ball for the first shot on each hole, they adjust the impact point position vertically to adjust the amount of spin and hit the ball with the ideal trajectory. From this perspective, the inventor has found that a technology that expands the high-repulsion area vertically to improve the flight distance of the shot is preferable for golfers who can hit the ball at the ideal impact point and adjust the impact point position vertically.

One of the objectives of the present invention is to provide a golf club head that can expand the high-repulsion area in the vertical direction and improve the flight distance of the ball.

In one embodiment, the present invention is a golf club head having a hollow portion therein. The head includes a face portion having a striking surface, a crown portion, and a sole portion. The face portion has a face main portion including a face center. The face main portion includes a central portion including the face center, a transition portion formed on the outside of the central portion, and a peripheral portion formed on the outside of the transition portion. The peripheral portion includes a first peripheral portion formed on each of the toe side and heel side of the face main portion, and a second peripheral portion formed on each of the crown side and sole side of the face main portion. The transition portion includes a first transition portion located between the central portion and the first peripheral portion, and a second transition portion located between the central portion and the second peripheral portion. The central portion has a central constant thickness and a surface area of 100 ^mm2 or more. The first peripheral portion has a first peripheral constant thickness, and the first peripheral constant thickness is greater than the central constant thickness. The second peripheral portion has a second constant peripheral thickness, the second constant peripheral thickness being less than the central constant thickness. The first transition portion has a thickness that increases from the central constant thickness to the first constant peripheral thickness. The second transition portion has a thickness that decreases from the central constant thickness to the second constant peripheral thickness.

As one aspect, a golf club head can be provided that has excellent repulsion performance at an impact point that is adjusted vertically.

FIG. 1 shows a golf club having a head according to a first embodiment. Fig. 2(a) is a front view of the head of the first embodiment, and Fig. 2(b) is a cross-section taken along line E1 in Fig. 2(a) In Fig. 2(b), only the cross-section line of the outer surface of the head is shown. FIG. 3 is the same front view as FIG. Fig. 4 is a front view similar to Fig. 2(a), in which the lines dividing the face portion into regions are indicated by dashed lines. Fig. 5 is a cross-sectional view showing a vertical section of the head of the first embodiment. Fig. 5 is a cross-sectional view passing through the face center. Fig. 6 is a cross-sectional view showing a cross section of the head of the first embodiment, the cross-sectional view passing through the face center. FIG. 7 is a front view of the head of the second embodiment. Fig. 8 is a front view similar to Fig. 7. In Fig. 8, lines dividing the regions of the face portion are indicated by dashed lines. Fig. 9 is a vertical cross-sectional view of the head of the second embodiment, taken along a cross-sectional surface passing through the face center. Fig. 10 is a cross-sectional view showing a cross section of the head of the second embodiment, taken along a cross section passing through the face center. FIG. 11 is a front view of the head of the third embodiment. Fig. 12 is a front view similar to Fig. 11. In Fig. 12, lines dividing the regions of the face portion are indicated by dashed lines. Fig. 13 is a cross-sectional view showing a vertical section of a head according to a third embodiment. Fig. 13 is a cross-sectional view passing through the face center. Fig. 14 is a cross-sectional view showing a cross section of a head according to a third embodiment. Fig. 14 is a cross-sectional view passing through the face center. FIG. 15 is a front view of the head of the fourth embodiment. Fig. 16 is a front view similar to Fig. 15. In Fig. 16, lines dividing the regions of the face portion are indicated by dashed lines. Fig. 17 is a cross-sectional view showing a vertical section of a head according to a fourth embodiment. Fig. 17 is a cross-sectional view passing through the face center. Fig. 18 is a cross-sectional view showing a cross section of a head according to a fourth embodiment. Fig. 18 is a cross-sectional view passing through the face center. FIG. 19 is a cross-sectional view showing a vertical section of the outer surface of the head of the third and fourth embodiments. FIG. 20 is a cross-sectional view showing a transverse section of the outer surface of the head of the third and fourth embodiments. FIG. 21 is a front view of the head of Comparative Example 1. FIG. Fig. 22 is the same front view as Fig. 21. In Fig. 22, lines dividing the respective regions of the face portion are indicated by dashed lines. FIG. 23 is a conceptual diagram for explaining the reference state.

The present invention will be described in detail below based on preferred embodiments, with reference to the drawings as appropriate. In each embodiment, identical or common elements are given the same reference numerals, and duplicate descriptions will be omitted as appropriate.

In this application, the reference state, reference vertical plane, toe-heel direction, face-back direction, up-down direction, face center, vertical section, horizontal section, and head front view are defined.

The state in which the head is placed on the ground plane HP at a specified lie angle is considered to be the reference state. As shown in FIG. 23, in this reference state, the shaft axis Z is included in a plane VP perpendicular to the ground plane HP. The shaft axis Z is the center line of the shaft. Usually, the shaft axis Z coincides with the center line of the hosel hole. The plane VP is considered to be the reference vertical plane. The specified lie angle is listed, for example, in the product catalog.

A club is known in which the loft angle, lie angle, and face angle can be adjusted by the rotational position of a sleeve attached to the tip of the shaft. In this club, the sleeve can be removably fixed to the head by a fixing means such as a screw. Therefore, in this club, the shaft can be attached and detached from the head. In a club having such a detachment mechanism, all adjustment items are neutral in the above-mentioned standard state. Neutral means the center of the adjustment range. The club of the present invention may have such a detachment mechanism.

In this reference state, the face angle is set to 0 degrees. That is, in a plan view from above, the normal line at the face center of the striking surface is perpendicular to the toe-heel direction. The face center and toe-heel direction are defined as described below.

In this specification, the toe-heel direction is the direction of the intersection line NL between the reference vertical plane VP and the ground plane HP (see FIG. 23). However, the toe-heel direction when the head is viewed from the front (front view) is the direction in which the toe-heel direction is projected onto the front view. The toe side in the toe-heel direction is also simply referred to as the "toe side". The heel side in the toe-heel direction is also simply referred to as the "heel side".

In this specification, the face-back direction is a direction perpendicular to the toe-heel direction and parallel to the ground plane HP. The face side in the face-back direction is also simply referred to as the "face side" or "front side." The back side in the face-back direction is also simply referred to as the "back side" or "rear side."

In this specification, the vertical direction is a direction perpendicular to the toe-heel direction and perpendicular to the face-back direction. In other words, in this specification, the vertical direction is a direction perpendicular to the ground plane HP. However, the vertical direction when viewed from the front of the head (front view) is the direction in which the vertical direction is projected onto the front view.

In this specification, the face center is determined as follows. First, an arbitrary point Pr is selected that is approximately near the center of the striking surface in the vertical and toe-heel directions. Next, a plane is determined that passes through this point Pr, extends along the normal direction of the striking surface at the point Pr, and is parallel to the toe-heel direction. A line of intersection between this plane and the striking surface is drawn, and its midpoint Px is determined. Next, a plane is determined that passes through this midpoint Px, extends along the normal direction of the striking surface at the point Px, and is parallel to the vertical direction. A line of intersection between this plane and the striking surface is drawn, and its midpoint Py is determined. Next, a plane is determined that passes through this midpoint Py, extends along the normal direction of the striking surface at the point Py, and is parallel to the toe-heel direction. A line of intersection between this plane and the striking surface is drawn, and its midpoint Px is newly determined. Next, a plane is determined that passes through this new midpoint Px, extends along the normal direction of the striking surface at the point Px, and is parallel to the vertical direction. A line of intersection between this plane and the striking surface is drawn, and its midpoint Py is determined. This process is repeated to determine Px and Py in sequence. In the repetition of this process, the new position Py (last position Py) when the distance between the new midpoint Py and the midpoint Py immediately preceding it is 0.5 mm or less for the first time is the face center.

In this specification, a longitudinal section is a section taken along a plane perpendicular to the toe-heel direction. A longitudinal section passing through the face center is also referred to as a center longitudinal section. In this specification, a transverse section is a section taken along a plane perpendicular to the up-down direction. In other words, in this specification, a transverse section is a section taken along a plane parallel to the ground plane HP. A transverse section passing through the face center is also referred to as a center transverse section.

In this specification, a front view of the head refers to a vertical projection of the head obtained with the normal line at the face center as the projection direction. Unless otherwise specified, the shape, area, dimensions, etc. of each area of the face portion are determined from the front view of the head. In this specification, a drawing of the head viewed from the front is also simply referred to as a front view.

[First embodiment]
FIG. 1 is an overall view of a golf club 2 including a head 4 according to a first embodiment of the present invention. FIG. 2(a) is a front view of the head 4, and FIG. 2(b) is a cross-sectional view taken along line E1 in FIG. 2(a). In FIG. 2(b), only the cross-sectional line of the outer surface of the head is shown. FIG. 3 and FIG. 4 are the same front views as FIG. 2(a). In FIG. 4, lines dividing the respective regions of the face portion 10 are shown by dashed lines. FIG. 5 is a cross-sectional view showing the longitudinal section of the head 4. FIG. 5 shows the central longitudinal section. FIG. 6 is a cross-sectional view showing the transverse section of the head 4. FIG. 6 shows the central transverse section.

As shown in FIG. 1, the golf club 2 includes a golf club head 4, a shaft 6, and a grip 8. The shaft 6 has a tip end Tp and a butt end Bt. The head 4 is attached to the tip end of the shaft 6. The grip 8 is attached to the butt end of the shaft 6.

Golf club 2 is a driver (No. 1 wood). Head 4 is a head for a driver. Typically, the club length of a driver is 43 inches or more and 48 inches or less. Preferably, golf club 2 is a wood type golf club or a hybrid type golf club.

The shaft 6 is a tubular body. The shaft 6 has a hollow structure. The material of the shaft 6 is carbon fiber reinforced resin. From the viewpoint of weight reduction, the material of the shaft 6 is preferably carbon fiber reinforced resin. The shaft 6 is a so-called carbon shaft. Preferably, the shaft 6 is formed by curing a prepreg sheet. In this prepreg sheet, the fibers are substantially oriented in one direction. A prepreg in which the fibers are substantially oriented in one direction in this manner is also called a UD prepreg. "UD" is an abbreviation for unidirectional. A prepreg other than a UD prepreg may be used. For example, the fibers contained in the prepreg sheet may be woven. The shaft 6 may include a metal wire. The material of the shaft 6 is not limited, and may be, for example, a metal.

The grip 8 is the part that is held by the golfer during the swing. Examples of materials for the grip 8 include a rubber composition and a resin composition. The rubber composition of the grip 8 may contain air bubbles.

The head 4 has a hollow structure. In this embodiment, the head 4 is a wood type. The head 4 may be a hybrid type. The head 4 may be an iron type. Preferably, the head 4 is a wood type or a hybrid type, and more preferably, the head 4 is a wood type.

The head 4 is, for example, mainly made of a metal material. In the embodiment described later, the head body may be made of a metal material, and the face member may be made of a metal material. The metal material is not particularly limited, but for example, pure titanium, titanium alloy, stainless steel, maraging steel, aluminum alloy, magnesium alloy, tungsten-nickel alloy, etc. may be used. A part of the head 4 (for example, the crown portion 12) may be made of a non-metallic material such as fiber reinforced resin. An example of the fiber reinforced resin is carbon fiber reinforced resin. The head 4 may be a composite head having a metal part and a fiber reinforced resin part. In the head 4 described later, the head body is made of a titanium alloy. In the head 4 described later, the face member is made of a titanium alloy.

The head 4 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking surface 10a and a face inner surface 10b. The striking surface 10a constitutes the outer surface of the face portion 10. The striking surface 10a has a face center Fc defined as described above. The hosel portion 16 has a shaft hole 16a.

The periphery k1 of the striking surface 10a can be defined as follows. As shown in Figures 2(a) and 2(b), there are cross sections E1, E2, E3, etc. that include a straight line connecting the center of gravity of the head 4 and the sweet spot SS. In each of these cross sections, a position Pe is determined where the radius of curvature r of the cross section line on the outer surface of the head first becomes 200 mm from the sweet spot SS side toward the outside of the striking surface 10a. This position Pe can be defined as the periphery k1 of the striking surface 10a. The sweet spot SS is the foot of a perpendicular line drawn from the center of gravity of the head 4 to the striking surface 10a.

From the viewpoint of the members constituting the head 4, the head 4 has a head body 4a and a face member 4b. As shown in FIG. 5 and FIG. 6, in the head 4, the head body 4a and the face member 4b are joined at the boundary k2. The boundary k2 coincides with the periphery k3 of the face member 4b. The head body 4a and the face member 4b are welded. The face member 4b constitutes a part of the striking surface 10a (a part including the face center Fc). The entire outer surface of the face member 4b is the striking surface 10a. The head body 4a is a plate-shaped member. Note that the face thickness may be locally increased at the boundary k2 due to the weld bead. In FIG. 5 and FIG. 6, the weld bead is not shown. Note that the face member 4b may not be used, and the integrally molded head body may include the face portion. The face member may also be a cup-shaped member including a part constituting the face portion and a rising part extending from that part to the back side.

The face portion 10 has a thickness. The thickness of the face portion 10 is defined by the striking surface 10a and the face inner surface 10b. The thickness of the face portion 10 is measured along the normal direction of the striking surface 10a. The face portion 10 has a thickness distribution. In this specification, when the thickness is compared between different regions and the thickness varies in the region, the thickness of the region can be considered as the average thickness. The average thickness is the thickness when the thickness is constant without changing the volume.

As shown in FIG. 4, the face portion 10 has a face main portion 20. The face main portion 20 includes a face center Fc. Preferably, the surface area of the face main portion 20 is 50% or more, even 55% or more, and even 60% or more of the surface area of the striking surface 10a. These surface areas are measured on the outer surface of the head 4, i.e., the striking surface 10a. If a face line is formed on the striking surface 10a, these surface areas are measured with the face line buried.

The face main portion 20 includes a central portion 22, a transition portion 24 formed outside the central portion 22, and a peripheral portion 26 formed outside the transition portion 24. In this embodiment, the periphery k4 of the face main portion 20 coincides with the periphery k3 of the face member 4b. The periphery k4 of the face main portion 20 does not have to coincide with the periphery k3 of the face member 4b.

The central portion 22 includes the face center Fc. The central portion 22 has a surface area of 100 ^mm2 or more. If a face line is formed on the striking surface 10a, this surface area is measured with the face line buried. The surface area of the central portion 22 is preferably 140 ^mm2 or more, more preferably 150 ^mm2 or more, and more preferably 250 ^mm2 or more. By increasing the surface area of the central portion 22, it is possible to increase the local deformation near the face center Fc, and thus the flight distance of the ball can be further increased.

On the other hand, from the viewpoint of ensuring durability at the face center Fc, the surface area of the central portion 22 is preferably 400 mm ² or less, more preferably 350 mm ² or less, and even more preferably 300 mm ² or less.

From another perspective, the surface area of the central portion 22 is preferably 5% or more and 15% or less of the area of the striking surface 10a. In this way, when the surface area of the central portion 22 is 5% or more of the area of the striking surface 10a, the local deformation near the face center Fc when hitting the ball can be made larger, and the flight distance of the ball can be further increased. From this perspective, the surface area of the central portion 22 is preferably 6% or more of the area of the striking surface 10a, and more preferably 7% or more. Also, when the surface area of the central portion 22 is 15% or less of the area of the striking surface 10a, the durability of the face portion 10 can be prevented from deteriorating. From this perspective, the surface area of the central portion 22 is more preferably 14% or less of the area of the striking surface 10a, and more preferably 13% or less. Note that the striking surface periphery k1 based on the above definition may not be an endless circular line, but may be a line with two ends. In this case, by connecting the two ends with a line segment, the striking surface periphery k1 can be made into an endless circular line, and the area of the striking surface 10a can be defined.

The central portion 22 has a constant thickness tc (see Figures 5 and 6). In this specification, the central portion 22 having a constant thickness includes not only the case where the same thickness continues along the striking surface 10a, but also the case where the thickness has a variation within the range of manufacturing errors and measurement errors that can inevitably occur. The thickness of the face portion 10 at the face center Fc is used as the reference for the central portion 22, and the portion that varies within ±0.05 mm from this thickness is considered to have the same thickness as the thickness at the face center Fc. In addition, if a face line is formed on the striking surface 10a, the thickness of each portion of the face portion 10 is measured with the face line buried. In order to distinguish it from other thicknesses, in this specification, the thickness tc of the central portion 22 is also referred to as the central constant thickness.

The thickness tc of the central portion 22 is preferably 2.5 mm or more, more preferably 2.6 mm or more, and more preferably 2.7 mm or more. This effectively prevents deterioration of the durability of the face portion 10. On the other hand, the thickness tc of the central portion 22 at the face center Fc is preferably 3.0 mm or less, more preferably 2.9 mm or less, and more preferably 2.8 mm or less. This allows for greater local deformation near the face center Fc when hitting the ball, further increasing the flight distance of the ball. In this embodiment, the thickness tc of the central portion 22 at the face center Fc is 2.75 mm.

As shown in FIG. 4, the contour of the central portion 22 (the contour identified by the contour line k5 of the central portion 22) has a shape that is longer in the toe-heel direction than in the vertical direction. The shape of the contour of the central portion 22 is close to an ellipse. This shape is an endless ring. This shape may be, for example, an ellipse or an oval. The striking surface 10a has a contour shape that is longer in the toe-heel direction than in the vertical direction. By making the contour shape of the central portion 22 correspond to that of the striking surface 10a, it is possible to effectively locally deform the face center Fc and its vicinity when striking a ball. Although not particularly limited, the maximum length of the central portion 22 in the toe-heel direction is 10 mm or more, more preferably 15 mm or more, and even more preferably 20 mm or more. Similarly, although not particularly limited, the maximum length of the central portion 22 in the vertical direction is preferably 10 mm or more, more preferably 15 mm or more.

The peripheral portion 26 is formed on the outside of the transition portion 24. The peripheral portion 26 includes a first peripheral portion 261 formed on each of the toe side and heel side of the face main portion 20, and a second peripheral portion 262 formed on each of the crown side and sole side of the face main portion 20. The first peripheral portion 261 is in contact with the periphery k4 of the face main portion 20. The second peripheral portion 262 is in contact with the periphery k4 of the face main portion 20.

The first peripheral portion 261 includes a toe-side first peripheral portion 26t located on the toe side of the central portion 22. Furthermore, the first peripheral portion 261 includes a heel-side first peripheral portion 26h located on the heel side of the central portion 22. The second peripheral portion 262 includes a crown-side second peripheral portion 26c located on the crown side of the central portion 22. Furthermore, the second peripheral portion 262 includes a sole-side second peripheral portion 26s located on the sole side of the central portion 22.

The first peripheral portion 261 has a constant thickness t1 (see FIG. 6). In this specification, the first peripheral portion 261 having a constant thickness includes not only the case where the same thickness continues along the striking surface 10a, but also the case where the thickness has variation within the range of manufacturing errors and measurement errors that may inevitably occur. For the first peripheral portion 261, a variation of ±0.05 mm is considered to be a constant thickness. To distinguish it from other thicknesses, in this specification, the thickness t1 of the first peripheral portion 261 is also referred to as the first peripheral portion constant thickness.

The first peripheral constant thickness t1 is greater than the central constant thickness tc. The first peripheral constant thickness t1 is preferably 2.8 mm or more, more preferably 2.9 mm or more, and more preferably 3.0 mm or more. This effectively prevents the durability of the face portion 10 from deteriorating. On the other hand, the first peripheral constant thickness t1 is preferably 3.4 mm or less, more preferably 3.3 mm or less, and more preferably 3.2 mm or less. This allows the local deformation near the face center Fc when hitting the ball to be greater, thereby increasing the flight distance of the ball. In this embodiment, the first peripheral constant thickness t1 is 3.1 mm. By increasing the first peripheral constant thickness t1, it is possible to increase durability while improving the repulsion performance near the face center Fc.

The second peripheral portion 262 has a constant thickness t2 (see FIG. 5). In this specification, the second peripheral portion 262 having a constant thickness includes not only the case where the exact same thickness continues along the striking surface 10a, but also the case where the thickness has variation within the range of manufacturing errors and measurement errors that may inevitably occur. For the second peripheral portion 262, a variation within ±0.05 mm is considered to be a constant thickness. To distinguish it from other thicknesses, in this specification, the thickness t2 of the second peripheral portion 262 is also referred to as the second peripheral portion constant thickness.

The second peripheral constant thickness t2 is smaller than the central constant thickness tc. The second peripheral constant thickness t2 is preferably 1.8 mm or more, more preferably 1.9 mm or more, and more preferably 2.0 mm or more. This effectively prevents the durability of the face portion 10 from deteriorating. On the other hand, the second peripheral constant thickness t2 is preferably 2.4 mm or less, more preferably 2.3 mm or less, and more preferably 2.2 mm or less. This allows the local high repulsion area to be expanded in the vertical direction when adjusting the impact point position in the vertical direction to hit different trajectories, thereby improving the flight distance of the ball. In this embodiment, the second peripheral constant thickness t2 is 2.1 mm. By reducing the second peripheral constant thickness t2, the local high repulsion area can be expanded in the vertical direction.

The surface area of the toe side first peripheral portion 26t is preferably 1% or more and 9% or less of the area of the striking surface 10a. By making the surface area of the toe side first peripheral portion 26t 1% or more of the area of the striking surface 10a, durability can be improved while improving the resilience performance near the face center Fc. From this perspective, the surface area of the toe side first peripheral portion 26t is preferably 2% or more of the area of the striking surface 10a, and more preferably 3% or more. From the perspective of resilience performance, the surface area of the toe side first peripheral portion 26t is preferably 9% or less of the area of the striking surface 10a, more preferably 8% or less, and more preferably 7% or less.

The surface area of the heel side first peripheral portion 26h is preferably 1% or more and 9% or less of the area of the striking surface 10a. By making the surface area of the heel side first peripheral portion 26h 1% or more of the area of the striking surface 10a, durability can be increased while improving the repulsion performance near the face center Fc. From this perspective, the surface area of the heel side first peripheral portion 26h is preferably 2% or more of the area of the striking surface 10a, and more preferably 3% or more. From the perspective of repulsion performance, the surface area of the heel side first peripheral portion 26h is preferably 9% or less of the area of the striking surface 10a, more preferably 8% or less, and more preferably 7% or less.

The surface area of the crown side second peripheral portion 26c is preferably 1% or more and 7% or less of the area of the striking surface 10a. From the viewpoint of expanding the high repulsion area in the vertical direction, the surface area of the crown side second peripheral portion 26c is preferably 1% or more of the area of the striking surface 10a, more preferably 2% or more, and even more preferably 3% or more. From the viewpoint of durability, the surface area of the crown side second peripheral portion 26c is preferably 7% or less of the area of the striking surface 10a, more preferably 6% or less, and even more preferably 5% or less.

The surface area of the sole side second peripheral portion 26s is preferably 1% or more and 7% or less of the area of the striking surface 10a. From the viewpoint of expanding the high-rebound area in the vertical direction, the surface area of the sole side second peripheral portion 26s is preferably 1% or more of the area of the striking surface 10a, more preferably 2% or more, and even more preferably 3% or more. From the viewpoint of durability, the surface area of the sole side second peripheral portion 26s is preferably 7% or less of the area of the striking surface 10a, more preferably 6% or less, and even more preferably 5% or less.

As shown in FIG. 4, the second perimeter 262 has a width B1. The width B1 is measured along a direction perpendicular to the boundary between the second perimeter 262 and the third perimeter 28. In this embodiment, the boundary between the second perimeter 262 and the third perimeter 28 coincides with the boundary k2.

From the viewpoint of expanding the high resilience area in the vertical direction, the width B1 of the second peripheral portion 262 is preferably 1 mm or more, more preferably 2 mm or more, and more preferably 3 mm or more. From the viewpoint of durability, the width B1 of the second peripheral portion 262 is preferably 7 mm or less, more preferably 6 mm or less, and more preferably 5 mm or less. The width B1 of the second peripheral portion 262 may or may not be constant. In this embodiment, the width B1 is constant. In this embodiment, the width B1 is 3 mm.

In FIG. 3, the double-headed arrow B3 indicates the vertical width of the striking surface 10a at the face center Fc. This vertical width B3 is measured along the vertical axis Z2.

The ratio of the width B1 of the second peripheral portion 262 to the vertical width B3 is B1/B3. From the viewpoint of expanding the high resilience area in the vertical direction, B1/B3 is preferably 0.02 or more, more preferably 0.04 or more, and even more preferably 0.06 or more. From the viewpoint of durability, B1/B3 is preferably 0.20 or less, more preferably 0.18 or less, and even more preferably 0.16 or less.

The transition portion 24 is formed on the outside of the central portion 22. The transition portion 24 is adjacent to the outside of the central portion 22. In other words, the transition portion 24 is continuous with the outside of the central portion 22.

The transition portion 24 includes a first transition portion 241 located between the central portion 22 and the first peripheral portion 261. Furthermore, the transition portion 24 includes a second transition portion 242 located between the central portion 22 and the second peripheral portion 262. The first peripheral portion 261 is continuous with the outer side of the first transition portion 241. The second peripheral portion 262 is continuous with the outer side of the second transition portion 242.

The first transition portion 241 includes a toe side first transition portion 24t that is connected to the toe side of the central portion 22. Furthermore, the first transition portion 241 includes a heel side first transition portion 24h that is connected to the heel side of the central portion 22. The second transition portion 242 includes a crown side second transition portion 24c that is connected to the crown side of the central portion 22. Furthermore, the second transition portion 242 includes a sole side second transition portion 24s that is connected to the sole side of the central portion 22.

The thickness t3 of the first transition portion 241 is equal to or greater than the central constant thickness tc. The thickness t3 of the first transition portion 241 is equal to or less than the first peripheral constant thickness t1. The thickness t3 of the first transition portion 241 increases continuously from the central constant thickness tc to the first peripheral constant thickness t1. By increasing the thickness t3 of the first transition portion 241, it is possible to increase durability while expanding the local high resilience area in the vertical direction. Furthermore, by continuously changing the thickness t3, it is possible to prevent stress concentration and increase durability.

The thickness t4 of the second transition portion 242 is equal to or greater than the second peripheral constant thickness t2. The thickness t4 of the second transition portion 242 is equal to or less than the central constant thickness tc. The thickness t4 of the second transition portion 242 decreases continuously from the central constant thickness tc to the second peripheral constant thickness t2. By reducing the thickness t4 of the second transition portion 242, the high resilience area can be expanded in the vertical direction. Furthermore, by continuously changing the thickness t4, stress concentration can be prevented and durability can be increased.

The face portion 10 further has a third peripheral portion 28. The third peripheral portion 28 is provided on the outside of the face main portion 20. The inner contour line of the third peripheral portion 28 coincides with the periphery k4 of the face main portion 20. The outer contour line of the third peripheral portion 28 coincides with the periphery k1 of the striking surface 10a. The third peripheral portion 28 surrounds the face main portion 20 continuously or intermittently. In the case of "intermittently," the third peripheral portion 28 may be missing at multiple points in the entire circumference (360 degrees) of the face main portion 20. In this case, it is preferable that the third peripheral portion 28 exists in 70% or more of the entire circumference (360 degrees) of the face main portion 20, more preferably that the third peripheral portion 28 exists in 80% or more of the entire circumference (360 degrees) of the face main portion 20, and more preferably that the third peripheral portion 28 exists in 90% or more of the entire circumference (360 degrees) of the face main portion 20. In the case of "continuously", the third peripheral portion 28 may surround the entire circumference (360 degrees) of the face main portion 20, but the third peripheral portion 28 may be missing at one point in the entire circumference (360 degrees) of the face main portion 20.

The third peripheral portion 28 has a thickness t5. In this embodiment, the thickness t5 of the third peripheral portion 28 is smaller than the central constant thickness tc. By reducing the thickness t5 of the third peripheral portion 28, the resilience performance can be further improved. When the thickness t5 of the third peripheral portion 28 is made smaller than the central constant thickness tc, this thickness t5 can be 2.7 mm or less, further 2.6 mm or less, or even 2.5 mm or less. From the viewpoint of durability, this thickness t5 can be 2.1 mm or more, further 2.2 mm or more, or even 2.3 mm or more.

The third peripheral portion 28 includes a crown-side third peripheral portion 28c located on the crown side and a sole-side third peripheral portion 28s located on the sole side. Furthermore, the third peripheral portion 28 includes a toe-side third peripheral portion 28t located on the toe side and a heel-side third peripheral portion 28h located on the heel side.

As shown in Figure 3, a parallel axis Z1 that extends in the toe-heel direction and passes through the face center Fc, and a vertical axis Z2 that extends perpendicular to the parallel axis Z1 and passes through the face center Fc are defined. In addition, a straight line L1 that passes through the face center Fc, forms an angle of 30 degrees with the parallel axis Z1, extends from the lower side of the toe toward the upper side of the heel, and a straight line L2 that passes through the face center Fc, forms an angle of 30 degrees with the parallel axis Z1, and extends from the upper side of the toe toward the lower side of the heel are defined.

The straight lines L1 and L2 can be dividing lines that divide the crown side third peripheral portion 28c, the sole side third peripheral portion 28s, the toe side third peripheral portion 28t, and the heel side third peripheral portion 28h.
A region that is toe side of the straight line L1 and heel side of the straight line L2 may be the crown region Rc. A region that is heel side of the straight line L1 and toe side of the straight line L2 may be the sole region Rs. A region that is above the straight line L1 and below the straight line L2 may be the toe region Rt. A region that is below the straight line L1 and above the straight line L2 may be the heel region Rh. A portion of the third peripheral portion 28 that belongs to the crown region Rc may be the crown side third peripheral portion 28c. A portion of the third peripheral portion 28 that belongs to the sole region Rs may be the sole side third peripheral portion 28s. A portion of the third peripheral portion 28 that belongs to the toe region Rt may be the toe side third peripheral portion 28t. A portion of the third peripheral portion 28 that belongs to the heel region Rh may be the heel side third peripheral portion 28h.

The crown side third peripheral portion 28c is connected to at least one selected from the group consisting of the first peripheral portion 261, the second peripheral portion 262, the first transition portion 241, and the second transition portion 242 on the crown side. In this embodiment, the crown side third peripheral portion 28c is connected to the first transition portion 241, the first peripheral portion 261, and the second peripheral portion 262 on the crown side. More specifically, the crown side third peripheral portion 28c is connected to the heel side first transition portion 24h, the crown side second peripheral portion 26c, and the toe side first peripheral portion 26t on the crown side.

The sole-side third peripheral portion 28s is connected to the sole side with at least one selected from the group consisting of the first peripheral portion 261, the second peripheral portion 262, the first transition portion 241, and the second transition portion 242. In this embodiment, the sole-side third peripheral portion 28s is connected to the first peripheral portion 261 and the second peripheral portion 262 on the sole side. More specifically, the crown-side third peripheral portion 28c is connected to the heel-side first peripheral portion 26h, the sole-side second peripheral portion 26s, and the toe-side first peripheral portion 26t on the sole side.

The toe side third peripheral portion 28t is connected to at least one selected from the group consisting of the first peripheral portion 261, the second peripheral portion 262, the first transition portion 241, and the second transition portion 242 on the toe side. In this embodiment, the toe side third peripheral portion 28t is connected to the first peripheral portion 261 on the toe side. More specifically, the toe side third peripheral portion 28t is connected to the toe side with the toe side first peripheral portion 26t.

The heel side third peripheral portion 28h is connected to at least one selected from the group consisting of the first peripheral portion 261, the second peripheral portion 262, the first transition portion 241, and the second transition portion 242 on the heel side. In this embodiment, the heel side third peripheral portion 28h is connected to the first peripheral portion 261 and the first transition portion 241 on the heel side. More specifically, the heel side third peripheral portion 28h is connected to the heel side first peripheral portion 26h and the heel side first transition portion 24h.

The thickness t51 of the sole-side third peripheral portion 28s is smaller than the thickness t52 of the crown-side third peripheral portion 28c (see FIG. 5).

The thickness t53 of the toe side third peripheral portion 28t is smaller than the thickness t52 of the crown side third peripheral portion 28c. The thickness t54 of the heel side third peripheral portion 28h is smaller than the thickness t52 of the crown side third peripheral portion 28c (see Figures 5 and 6).

The third peripheral portion 28 has transition portions 29a provided on the toe side and the heel side. The transition portions 29a provided on the third peripheral portion 28 are called peripheral transition portions. The peripheral transition portion 29a is composed of a toe peripheral transition portion 29t located on the toe side and a heel peripheral transition portion 29h located on the heel side. The toe peripheral transition portion 29t and the heel peripheral transition portion 29h divide the third peripheral portion 28 into a crown side region 29c and a sole side region 29s. These divisions (29t, 29h, 29c, 29s) of the third peripheral portion 28 are separate from the above-mentioned divisions (28t, 28h, 28c, 28s) of the third peripheral portion 28.

The crown side region 29c is connected to the toe peripheral transition portion 29t and the heel peripheral transition portion 29h on the crown side. The sole side region 29s is connected to the toe peripheral transition portion 29t and the heel peripheral transition portion 29h on the sole side. The thickness of each of the toe peripheral transition portion 29t and the heel peripheral transition portion 29h changes from the thickness of the sole side region 29s to the thickness of the crown side region 29c.

The crown side region 29c is connected to at least one selected from the group consisting of the first peripheral portion 261, the second peripheral portion 262, the first transition portion 241, and the second transition portion 242 on the crown side. In this embodiment, the crown side region 29c is connected to the first transition portion 241, the first peripheral portion 261, and the second peripheral portion 262 on the crown side. More specifically, the crown side region 29c is connected to the heel side first peripheral portion 26h, the heel side first transition portion 24h, the crown side second peripheral portion 26c, and the toe side first peripheral portion 26t on the crown side.

The sole side region 29s is connected to at least one selected from the group consisting of the first peripheral portion 261, the second peripheral portion 262, the first transition portion 241, and the second transition portion 242 on the sole side. In this embodiment, the sole side region 29s is connected to the first peripheral portion 261 and the second peripheral portion 262 on the sole side. More specifically, the sole side region 29s is connected to the heel side first peripheral portion 26h, the sole side second peripheral portion 26s, and the toe side first peripheral portion 26t on the sole side.

The toe peripheral transition portion 29t is connected to at least one selected from the group consisting of the first peripheral portion 261, the second peripheral portion 262, the first transition portion 241, and the second transition portion 242 on the toe side. In this embodiment, the toe peripheral transition portion 29t is connected to the first peripheral portion 261 on the toe side. More specifically, the toe peripheral transition portion 29t is connected to the toe side with the toe side first peripheral portion 26t.

The heel periphery transition portion 29h is connected to at least one selected from the group consisting of the first periphery portion 261, the second periphery portion 262, the first transition portion 241, and the second transition portion 242 on the heel side. In this embodiment, the heel periphery transition portion 29h is connected to the first periphery portion 261 on the heel side. More specifically, the heel periphery transition portion 29h is connected to the heel side of the heel side first periphery portion 26h.

The crown side region 29c and the sole side region 29s have different thicknesses. The peripheral transition portion 29a has a thickness that changes from the thickness of the crown side region 29c to the thickness of the sole side region 29s. In this embodiment, the thickness of the crown side region 29c is greater than the thickness of the sole side region 29s. The thickness of the toe peripheral transition portion 29t is less than the thickness of the crown side region 29c. The thickness of the heel peripheral transition portion 29h is less than the thickness of the crown side region 29c. The thickness of the toe peripheral transition portion 29t is greater than the thickness of the sole side region 29s. The thickness of the heel peripheral transition portion 29h is greater than the thickness of the sole side region 29s.

The crown side region 29c includes the entire crown side third peripheral portion 28c. The crown side region 29c also includes a portion of the toe side third peripheral portion 28t. The crown side region 29c also includes a portion of the heel side third peripheral portion 28h. The sole side region 29s includes the entire sole side third peripheral portion 28s. The sole side region 29s also includes a portion of the toe side third peripheral portion 28t. The sole side region 29s also includes a portion of the heel side third peripheral portion 28h.

As shown in FIG. 4, the face portion 10 has a third transition portion 30. The third transition portion 30 extends along a line that is inclined at ±20 to 70 degrees with respect to a parallel axis Z1 (see FIG. 3) that extends in the toe-heel direction and passes through the face center Fc. The shape of this line is not limited, and may be a straight line, a broken line, or a curve. The center line CL1 of the third transition portion 30 is inclined at an angle of ±20 degrees or more and 70 degrees or less with respect to the parallel axis Z1. The angle θ shown in FIG. 4 is an angle of ±20 degrees or more and 70 degrees or less.

The third transition portion 30 has a width B2. The width B2 is measured along a direction perpendicular to the contour line 30a of the toe side of the third transition portion 30. From the viewpoint of ensuring the area of other regions, the width B2 of the third transition portion 30 is made small. The width B2 is preferably 7 mm or less, more preferably 6 mm or less, and more preferably 5 mm or less. From the viewpoint of gradual change in face thickness and easy molding of the face portion, the width B2 of the third transition portion 30 is preferably 1 mm or more, more preferably 2 mm or more, and more preferably 3 mm or more. The width B2 of the third transition portion 30 may or may not be constant. In this embodiment, the width B2 is constant. In this embodiment, the width B2 is 3 mm.

The third transition portion 30 is provided in the face main portion 20. The third transition portion 30 is provided in at least one location. In the embodiment of FIG. 4, the third transition portion 30 is provided in four locations. The third transition portion 30 includes a toe-upper third transition portion 301 located on the toe side and crown side of the face center Fc, a heel-upper third transition portion 302 located on the heel side and crown side of the face center Fc, a heel-lower third transition portion 303 located on the heel side and sole side of the face center Fc, and a toe-lower third transition portion 304 located on the toe side and sole side of the face center Fc.

The toe upper third transition portion 301 extends at an angle toward the crown as it approaches the toe side. The toe upper third transition portion 301 extends from the central portion 22 to the third peripheral portion 28. The toe upper third transition portion 301 extends from the contour line k5 of the central portion 22 to the periphery k4 of the face main portion 20.

The heel-upper third transition portion 302 extends at an angle toward the crown as it approaches the heel side. The heel-upper third transition portion 302 extends from the central portion 22 to the third peripheral portion 28. The heel-upper third transition portion 302 extends from the contour line k5 of the central portion 22 to the periphery k4 of the face main portion 20.

The heel-underside third transition portion 303 extends at an angle toward the sole side as it approaches the heel side. The heel-underside third transition portion 303 extends from the central portion 22 to the third peripheral portion 28. The heel-underside third transition portion 303 extends from the contour line k5 of the central portion 22 to the periphery k4 of the face main portion 20.

The third transition section 304 below the toe extends at an angle toward the sole side as it approaches the toe side. The third transition section 304 below the toe extends from the central portion 22 to the third peripheral portion 28. The third transition section 304 below the toe extends from the contour line k5 of the central portion 22 to the periphery k4 of the face main portion 20.

The third transition portion 30 is located between at least one of the first peripheral portion 261 and the first transition portion 241 and at least one of the second peripheral portion 262 and the second transition portion 242.

The toe upper third transition portion 301 is located between the first transition portion 241 and the second transition portion 242, and between the first transition portion 241 and the second peripheral portion 262. More specifically, the toe upper third transition portion 301 is located between the toe side first transition portion 24t and the crown side second transition portion 24c. The third transition portion 301 is adjacent to the toe side first transition portion 24t and the crown side second transition portion 24c. The toe upper third transition portion 301 is also located between the toe side first transition portion 24t and the crown side second peripheral portion 26c. The toe upper third transition portion 301 is adjacent to the toe side first transition portion 24t and the crown side second peripheral portion 26c.

The heel upper third transition portion 302 is located between the first transition portion 241 and the second transition portion 242, and between the first transition portion 241 and the second peripheral portion 262. More specifically, the heel upper third transition portion 302 is located between the heel side first transition portion 24h and the crown side second transition portion 24c. The heel upper third transition portion 302 is adjacent to the heel side first transition portion 24h and the crown side second transition portion 24c. The heel upper third transition portion 302 is also located between the heel side first transition portion 24h and the crown side second peripheral portion 26c. The heel upper third transition portion 302 is adjacent to the heel side first transition portion 24h and the crown side second peripheral portion 26c.

The heel underside third transition portion 303 is located between the first transition portion 241 and the second transition portion 242, and between the first transition portion 241 and the second peripheral portion 262. More specifically, the heel underside third transition portion 303 is located between the heel side first transition portion 24h and the sole side second transition portion 24s. The heel underside third transition portion 303 is adjacent to the heel side first transition portion 24h and the sole side second transition portion 24s. The heel underside third transition portion 303 is also located between the heel side first transition portion 24h and the sole side second peripheral portion 26s. The heel underside third transition portion 303 is adjacent to the heel side first transition portion 24h and the sole side second peripheral portion 26s.

The toe lower third transition portion 304 is located between the first transition portion 241 and the second transition portion 242, and between the first transition portion 241 and the second peripheral portion 262. More specifically, the toe lower third transition portion 304 is located between the toe side first transition portion 24t and the sole side second transition portion 24s. The toe lower third transition portion 304 is adjacent to the toe side first transition portion 24t and the sole side second transition portion 24s. The toe lower third transition portion 304 is also located between the toe side first transition portion 24t and the sole side second peripheral portion 26s. The toe lower third transition portion 304 is adjacent to the toe side first transition portion 24t and the sole side second peripheral portion 26s.

Each of these third transitional parts 30 has a thickness that changes continuously so that no step occurs due to a difference in thickness between adjacent regions through the third transitional part 30. As shown in FIG. 4, the face main part 20 is divided into four regions, the first region R1 to the fourth region R4, by the central part 22 and the four third transitional parts 30 extending from the central part 22 toward the peripheral side of the face part 10. The first region R1 located on the crown side includes the crown side second transitional part 24c and the crown side second peripheral part 26c. The second region R2 located on the heel side includes the heel side first transitional part 24h and the heel side first peripheral part 26h. The third region R3 located on the sole side includes the sole side second transitional part 24s and the sole side second peripheral part 26s. The fourth region R4, located on the toe side, includes the toe side first transition portion 24t and the toe side first peripheral portion 26t. The third transition portion 30 prevents stress concentration and contributes to improving durability.

[Second embodiment]
Fig. 7 is a front view of the head 42 of the second embodiment, Fig. 8 is a front view of the head 42 in which the lines dividing the regions of the face portion 10 are indicated by dashed lines, Fig. 9 is a cross-sectional view showing the vertical section of the head 42, and Fig. 10 is a cross-sectional view showing the horizontal section of the head 42. Fig. 9 shows the vertical section of the center, and Fig. 10 shows the horizontal section of the center.

The head 42 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking surface 10a and a face inner surface 10b. The hosel portion 16 has a shaft hole 16a.

As shown in Fig. 8, the face portion 10 has a face main portion 20. The face main portion 20 includes a central portion 22, a transition portion 24 formed outside the central portion 22, and a peripheral portion 26 formed outside the transition portion 24. The central portion 22 includes a face center Fc. The central portion 22 has a surface area of 100 ^mm2 or more. The central portion 22 has a constant thickness tc.

The peripheral portion 26 is formed on the outside of the transition portion 24. The peripheral portion 26 includes a first peripheral portion 261 formed on each of the toe side and heel side of the face main portion 20, and a second peripheral portion 262 formed on each of the crown side and sole side of the face main portion 20.

The first peripheral portion 261 includes a toe-side first peripheral portion 26t located on the toe side of the central portion 22. Furthermore, the first peripheral portion 261 includes a heel-side first peripheral portion 26h located on the heel side of the central portion 22. The second peripheral portion 262 includes a crown-side second peripheral portion 26c located on the crown side of the central portion 22. Furthermore, the second peripheral portion 262 includes a sole-side second peripheral portion 26s located on the sole side of the central portion 22. The first peripheral portion 261 has a constant thickness (first peripheral constant thickness) t1. The second peripheral portion 262 has a constant thickness (second peripheral constant thickness) t2. The second peripheral constant thickness t2 is smaller than the central constant thickness tc.

The transition portion 24 is formed on the outside of the central portion 22. The transition portion 24 is connected to the outside of the central portion 22. The transition portion 24 includes a first transition portion 241 located between the central portion 22 and a first peripheral portion 261. Furthermore, the transition portion 24 includes a second transition portion 242 located between the central portion 22 and a second peripheral portion 262. The first peripheral portion 261 is connected to the outside of the first transition portion 241. The second peripheral portion 262 is connected to the outside of the second transition portion 242.

The first transition portion 241 includes a toe side first transition portion 24t that is connected to the toe side of the central portion 22. Furthermore, the first transition portion 241 includes a heel side first transition portion 24h that is connected to the heel side of the central portion 22. The second transition portion 242 includes a crown side second transition portion 24c that is connected to the crown side of the central portion 22. Furthermore, the second transition portion 242 includes a sole side second transition portion 24s that is connected to the sole side of the central portion 22.

The thickness t3 of the first transition portion 241 is equal to or greater than the central constant thickness tc. The thickness t3 of the first transition portion 241 is equal to or less than the first peripheral constant thickness t1. The thickness t3 of the first transition portion 241 increases from the central constant thickness tc toward the first peripheral constant thickness t1. The maximum thickness of the first transition portion 241 (maximum value of thickness t3) is greater than the central constant thickness tc.

The thickness t4 of the second transition portion 242 is equal to or greater than the second constant peripheral thickness t2. The thickness t4 of the second transition portion 242 is equal to or less than the constant central thickness tc. The thickness t4 of the second transition portion 242 decreases from the constant central thickness tc toward the second constant peripheral thickness t2. The minimum thickness of the second transition portion 242 (the minimum value of thickness t4) is smaller than the constant central thickness tc.

The face portion 10 further has a third peripheral portion 28. The third peripheral portion 28 is provided on the outside of the face main portion 20. The third peripheral portion 28 continuously surrounds the face main portion 20. The third peripheral portion 28 includes a crown-side third peripheral portion 28c located on the crown side, and a sole-side third peripheral portion 28s located on the sole side. The third peripheral portion 28 further includes a toe-side third peripheral portion 28t located on the toe side, and a heel-side third peripheral portion 28h located on the heel side.

The third peripheral portion 28 includes peripheral transition portions 29a provided on the toe side and the heel side. The peripheral transition portion 29a is composed of a toe peripheral transition portion 29t and a heel peripheral transition portion 29h. The third peripheral portion 28 has a crown side region 29c and a sole side region 29s that are partitioned by the peripheral transition portion 29a. The crown side region 29c and the sole side region 29s have different thicknesses. In this embodiment, the thickness of the crown side region 29c is greater than the thickness of the sole side region 29s. The thickness of the toe peripheral transition portion 29t is less than the thickness of the crown side region 29c. The thickness of the heel peripheral transition portion 29h is less than the thickness of the crown side region 29c. The thickness of the toe peripheral transition portion 29t is greater than the thickness of the sole side region 29s. The thickness of the heel peripheral transition portion 29h is greater than the thickness of the sole side region 29s.

The face portion 10 has a third transition portion 30. The third transition portion 30 is provided in the face main portion 20. The third transition portion 30 is provided in four locations. The third transition portion 30 includes a toe-upper third transition portion 301 located on the toe side and crown side of the face center Fc, a heel-upper third transition portion 302 located on the heel side and crown side of the face center Fc, a heel-lower third transition portion 303 located on the heel side and sole side of the face center Fc, and a toe-lower third transition portion 304 located on the toe side and sole side of the face center Fc.

The difference between this head 42 and the head 4 of the first embodiment is the thickness t5 of the third peripheral portion 28. Except for the thickness t5 of the third peripheral portion 28, the head 42 of the second embodiment is the same as the head 4.

In the head 42, the thickness t5 of the third peripheral portion 28 is made thicker. The thickness t5 of the third peripheral portion 28 is greater than the constant central thickness tc (see Figures 9 and 10). By making the thickness t5 of the third peripheral portion 28 larger, durability can be improved while maintaining the high repulsion area extending in the vertical direction from the face center. When the thickness t5 of the third peripheral portion 28 is made larger than the constant central thickness tc, this thickness t5 can be 2.7 mm or more, further 2.8 mm or more, and further 2.9 mm or more. An excessive thickness t5 reduces the degree of freedom of the thickness distribution of the face portion 10. From this viewpoint, the thickness t5 is preferably 3.3 mm or less, more preferably 3.2 mm or less, and more preferably 3.1 mm or less.

The thickness t51 of the sole side third peripheral portion 28s is smaller than the thickness t52 of the crown side third peripheral portion 28c. The thickness t53 of the toe side third peripheral portion 28t is smaller than the thickness t52 of the crown side third peripheral portion 28c. The thickness t54 of the heel side third peripheral portion 28h is smaller than the thickness t52 of the crown side third peripheral portion 28c.

[Third embodiment]
Fig. 11 is a front view of a head 43 of the third embodiment, Fig. 12 is a front view of the head 43 in which the lines dividing the respective regions of the face portion 10 are indicated by dashed lines, Fig. 13 is a cross-sectional view showing a vertical section of the head 43, and Fig. 14 is a cross-sectional view showing a horizontal section of the head 43. Fig. 13 shows a center vertical section, and Fig. 14 shows a center horizontal section.

The head 43 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking surface 10a and a face inner surface 10b. The hosel portion 16 has a shaft hole 16a.

As shown in Fig. 12, the face portion 10 has a face main portion 20. The face main portion 20 includes a central portion 22, a transition portion 24 formed outside the central portion 22, and a peripheral portion 26 formed outside the transition portion 24. The central portion 22 includes a face center Fc. The central portion 22 has a surface area of 100 ^mm2 or more. The central portion 22 has a constant thickness tc.

The peripheral portion 26 is formed on the outside of the transition portion 24. The peripheral portion 26 includes a first peripheral portion 261 and a second peripheral portion 262. The first peripheral portion 261 includes a toe-side first peripheral portion 26t located on the toe side of the central portion 22, and a heel-side first peripheral portion 26h located on the heel side of the central portion 22. The second peripheral portion 262 includes a crown-side second peripheral portion 26c located on the crown side of the central portion 22, and a sole-side second peripheral portion 26s located on the sole side of the central portion 22. The first peripheral portion 261 has a first peripheral constant thickness t1. The second peripheral portion 262 has a second peripheral constant thickness t2. The second peripheral constant thickness t2 is smaller than the central constant thickness tc.

The transition portion 24 includes a first transition portion 241 located between the central portion 22 and the first peripheral portion 261, and a second transition portion 242 located between the central portion 22 and the second peripheral portion 262. The first peripheral portion 261 is connected to the outside of the first transition portion 241. The second peripheral portion 262 is connected to the outside of the second transition portion 242.

The first transition portion 241 includes a toe-side first transition portion 24t that connects to the toe side of the central portion 22, and a heel-side first transition portion 24h that connects to the heel side of the central portion 22. The second transition portion 242 includes a crown-side second transition portion 24c that connects to the crown side of the central portion 22, and a sole-side second transition portion 24s that connects to the sole side of the central portion 22.

The thickness t3 of the first transition portion 241 is equal to or greater than the central constant thickness tc. The thickness t3 of the first transition portion 241 is equal to or less than the first peripheral constant thickness t1. The thickness t3 of the first transition portion 241 increases from the central constant thickness tc toward the first peripheral constant thickness t1.

The thickness t4 of the second transition portion 242 is equal to or greater than the second constant peripheral thickness t2. The thickness t4 of the second transition portion 242 is equal to or less than the central constant thickness tc. The thickness t4 of the second transition portion 242 decreases from the central constant thickness tc toward the second constant peripheral thickness t2.

The face portion 10 further has a third peripheral portion 28. The third peripheral portion 28 continuously surrounds the main face portion 20. The third peripheral portion 28 includes a crown-side third peripheral portion 28c located on the crown side, and a sole-side third peripheral portion 28s located on the sole side. The third peripheral portion 28 further includes a toe-side third peripheral portion 28t located on the toe side, and a heel-side third peripheral portion 28h located on the heel side.

The third peripheral portion 28 includes peripheral transition portions 29a provided on the toe side and the heel side. The peripheral transition portion 29a is composed of a toe peripheral transition portion 29t and a heel peripheral transition portion 29h. The third peripheral portion 28 has a crown side region 29c and a sole side region 29s. The thickness of the crown side region 29c is greater than the thickness of the sole side region 29s. The thickness of the toe peripheral transition portion 29t is less than the thickness of the crown side region 29c. The thickness of the heel peripheral transition portion 29h is less than the thickness of the crown side region 29c. The thickness of the toe peripheral transition portion 29t is greater than the thickness of the sole side region 29s. The thickness of the heel peripheral transition portion 29h is greater than the thickness of the sole side region 29s.

The face portion 10 has a third transition portion 30. The third transition portion 30 is provided in a plurality of dispersed locations. The third transition portion 30 includes a toe-upper third transition portion 301 located on the toe side and crown side of the face center Fc, a heel-upper third transition portion 302 located on the heel side and crown side of the face center Fc, a heel-lower third transition portion 303 located on the heel side and sole side of the face center Fc, and a toe-lower third transition portion 304 located on the toe side and sole side of the face center Fc.

The thickness t5 of the third peripheral portion 28 is smaller than the central constant thickness tc (see Figures 13 and 14). The thickness t51 of the sole-side third peripheral portion 28s is smaller than the thickness t52 of the crown-side third peripheral portion 28c. The thickness t53 of the toe-side third peripheral portion 28t is smaller than the thickness t52 of the crown-side third peripheral portion 28c. The thickness t54 of the heel-side third peripheral portion 28h is smaller than the thickness t52 of the crown-side third peripheral portion 28c.

The difference between this head 43 and the head 4 of the first embodiment is the cross-sectional shape of the toe side of the face portion 10 and the shape of the bulge and roll around the periphery of the striking surface 10a. Apart from these two differences, the head 43 is the same as the head 4 of the first embodiment.

Regarding the first difference (difference A), in the head 43, the cross-sectional shape of the portion (toe portion) Pt (see FIG. 14) on the toe side of the face portion 10 is rounded compared to the head 4. As a result, the position of the periphery k1 of the striking surface 10a on the toe side is moved toward the heel side compared to the head 4. As shown in FIG. 11, the head 43 has a toe point T1. When viewed from the front of the head, the toe point T1 is the intersection point of the parallel axis Z1 and the striking surface periphery k1, which is located on the toe side. The head 43 also has a heel point H1. In the head 43 in the reference state, an intersection line between the horizontal plane located 0.875 inches above the ground plane HP and the outer surface of the head 43 is determined. On this intersection line, the point located closest to the heel side is the heel point H1. In a front view of the head, the toe-heel distance between the face center Fc and the toe point T1 is W1, and the toe-heel distance between the face center Fc and the heel point H1 is W2. By rounding the toe portion Pt, the toe point T1 moves toward the heel side, and W1/W2 becomes smaller. From the viewpoint of durability, W1/W2 can be set to 0.90 or less, further 0.86 or less, and further 0.82 or less. If the toe portion Pt is rounded excessively, the area of the striking surface 10a may become too small. From this viewpoint, W1/W2 can be set to 0.70 or more, further 0.75 or more, and further 0.80 or more. Due to this rounded shape on the toe side, the extension direction of the cross section on the toe side of the face portion approaches the normal direction of the striking surface, so that the rigidity of the face portion during striking on the toe side is increased. As a result, durability is further improved. From the same viewpoint, the distance W3 in the toe-heel direction from the heel point H1 to the toe point T1 is preferably equal to or less than 98 mm, more preferably equal to or less than 96 mm, and still more preferably equal to or less than 94 mm. The head 43 is a driver head, and the head volume can be set to 440 ^cm3 or more, further 450 ^cm3 or more, and further 460 ^cm3 or more (the upper limit of the head volume can be set to 470 ^cm3 or less). From this viewpoint, the distance W3 is preferably equal to or less than 84 mm, more preferably equal to or less than 86 mm, and still more preferably equal to or less than 88 mm.

Regarding the second difference (difference B), in head 43, the periphery of the striking surface 10a is rounded compared to head 4. In head 43, the roll radius of the upper and lower regions that are 7.5 mm or more above and below the parallel axis Z1 is smaller than the roll radius of the vertical central region. In addition, the bulge radius of the left and right regions that are 20.0 mm or more above and below the vertical axis Z2 are smaller than the bulge radius of the left and right central region that is within 20.0 mm of the vertical axis Z2. Details of difference B will be described later.

[Fourth embodiment]
Fig. 15 is a front view of a head 44 according to a fourth embodiment, Fig. 16 is a front view of the head 44 in which the lines dividing the regions of the face portion 10 are indicated by dashed lines, Fig. 17 is a cross-sectional view showing a vertical section of the head 44, and Fig. 18 is a cross-sectional view showing a horizontal section of the head 44. Figs. 17 and 18 are cross-sectional views passing through the face center Fc.

The head 44 has a face portion 10, a crown portion 12, a sole portion 14, and a hosel portion 16. The face portion 10 has a striking surface 10a and a face inner surface 10b. The hosel portion 16 has a shaft hole 16a.

16 , the face portion 10 has a face main portion 20. The face main portion 20 includes a central portion 22, a transition portion 24 formed outside the central portion 22, and a peripheral portion 26 formed outside the transition portion 24. The central portion 22 includes a face center Fc. The central portion 22 has a surface area of 100 ^mm2 or more. The central portion 22 has a constant thickness tc.

The peripheral portion 26 is formed on the outside of the transition portion 24. The peripheral portion 26 includes a first peripheral portion 261 and a second peripheral portion 262. The first peripheral portion 261 includes a toe side first peripheral portion 26t and a heel side first peripheral portion 26h. The second peripheral portion 262 includes a crown side second peripheral portion 26c and a sole side second peripheral portion 26s. The first peripheral portion 261 has a first peripheral constant thickness t1. The second peripheral portion 262 has a second peripheral constant thickness t2. The second peripheral constant thickness t2 is smaller than the central constant thickness tc.

The transition portion 24 includes a first transition portion 241 and a second transition portion 242. A first peripheral portion 261 is connected to the outside of the first transition portion 241. A second peripheral portion 262 is connected to the outside of the second transition portion 242. The first transition portion 241 includes a toe side first transition portion 24t and a heel side first transition portion 24h. The second transition portion 242 includes a crown side second transition portion 24c and a sole side second transition portion 24s.

The thickness t3 of the first transition portion 241 is equal to or greater than the central constant thickness tc. The thickness t3 of the first transition portion 241 is equal to or less than the first peripheral constant thickness t1. The thickness t3 of the first transition portion 241 increases from the central constant thickness tc toward the first peripheral constant thickness t1.

The thickness t4 of the second transition portion 242 is equal to or greater than the second constant peripheral thickness t2. The thickness t4 of the second transition portion 242 is equal to or less than the central constant thickness tc. The thickness t4 of the second transition portion 242 decreases from the central constant thickness tc toward the second constant peripheral thickness t2.

The face portion 10 further has a third peripheral portion 28. The third peripheral portion 28 is connected to the outside of the face main portion 20. The third peripheral portion 28 continuously surrounds the face main portion 20. The third peripheral portion 28 includes a crown side third peripheral portion 28c and a sole side third peripheral portion 28s. The third peripheral portion 28 further includes a toe side third peripheral portion 28t and a heel side third peripheral portion 28h.

The third peripheral portion 28 includes a peripheral transition portion 29a. The peripheral transition portion 29a is composed of a toe peripheral transition portion 29t and a heel peripheral transition portion 29h. The third peripheral portion 28 has a crown side region 29c and a sole side region 29s. The thickness of the crown side region 29c is greater than the thickness of the sole side region 29s. The thickness of the toe peripheral transition portion 29t is less than the thickness of the crown side region 29c. The thickness of the heel peripheral transition portion 29h is less than the thickness of the crown side region 29c. The thickness of the toe peripheral transition portion 29t is greater than the thickness of the sole side region 29s. The thickness of the heel peripheral transition portion 29h is greater than the thickness of the sole side region 29s.

The face portion 10 has a third transition portion 30. The third transition portion 30 is provided in a plurality of dispersed locations. The third transition portion 30 includes a toe-upper third transition portion 301, a heel-upper third transition portion 302, a heel-lower third transition portion 303, and a toe-lower third transition portion 304.

The thickness t5 of the third peripheral portion 28 is smaller than the central constant thickness tc (see Figures 17 and 18). The thickness t51 of the sole-side third peripheral portion 28s is smaller than the thickness t52 of the crown-side third peripheral portion 28c. The thickness t53 of the toe-side third peripheral portion 28t is smaller than the thickness t52 of the crown-side third peripheral portion 28c. The thickness t54 of the heel-side third peripheral portion 28h is smaller than the thickness t52 of the crown-side third peripheral portion 28c.

The difference between this head 44 and the head 43 of the third embodiment is the thickness of the crown portion. Except for this, the head 44 is the same as the head 43 of the third embodiment. Like the head 43, the head 44 has the difference A and the difference B with respect to the head 4. In addition, the head 44 has a difference (difference C) from the head 43 of the third embodiment.

The difference C (thickness of the crown front portion) of the head 44 is as follows. As shown in FIG. 17, the crown portion 12 of the head 44 has a crown front portion 12a. In the longitudinal section of the head 44, a tangent S1 is determined at the center point of the striking surface 10a. This center point is a point located on the parallel axis Z1 when viewed from the front of the head. As shown in FIG. 17, in the longitudinal section including the face center Fc, this center point is the face center Fc. In the direction perpendicular to the tangent S1, the distance D1 between the front end 46 of the crown front portion 12a and the tangent S1 is 9 mm or more and 13 mm or less. In this embodiment, the distance D1 is 11 mm. In the direction perpendicular to the tangent S1, the width D2 of the crown front portion 12a can be 4 mm or more and 8 mm or less. In this embodiment, the width D2 is 6 mm. This crown front portion 12a is a thin portion having a thickness t6 of 0.3 mm or more and 0.6 mm or less, more preferably 0.4 mm or more and 0.5 mm or less. A transition portion 12b is formed between the face portion 10 and the crown front portion 12a. The thickness of the transition portion 12b is continuously reduced from the face portion 10 toward the crown front portion 12a. This thin-walled crown front portion 12a contributes to improving the repulsion performance.

[Bulge and roll roundness around the ball-hitting surface]
The difference B between the head 43 and the head 44 (the rounded shape of the periphery of the ball-striking surface) is as follows.

Figure 19 is a vertical cross-sectional view of the outer surface of heads 43 and 44, and Figure 20 is a horizontal cross-sectional view of the outer surface of heads 43 and 44.

As described above, a parallel axis Z1 that passes through the face center Fc and extends in the toe-heel direction, and a vertical axis Z2 that passes through the face center Fc and extends in the up-down direction are defined. In the longitudinal cross-sectional view of FIG. 19, the parallel axis Z1 is indicated by a dot. In the transverse cross-sectional view of FIG. 20, the vertical axis Z2 is indicated by a dot.

As shown in the vertical cross section of Figure 19, the striking surface 10a has a vertical cross section center point P1. The vertical cross section center point P1 is a point located on the parallel axis Z1 when the head is viewed from the front (see Figure 3). Since Figure 19 is a center vertical cross section, the vertical cross section center point P1 is the face center Fc.

In the longitudinal section, the striking surface 10a has a tangent line S1 at the longitudinal section center point P1. In FIG. 19, the tangent line S1 is shown by a two-dot chain line.

The striking surface 10a has a point P2 that is 7.5 mm above the center point P1 of the longitudinal section, and a point P3 that is 7.5 mm below the center point P1. These 7.5 mm are measured along the direction of the tangent line S1. The striking surface 10a has a point P4 on the striking surface periphery k1 that is located above point P2, and a point P5 on the striking surface periphery k1 that is located below point P3. The striking surface 10a has a point P6 between points P2 and P4. The distance from point P6 to point P4 is equal to the distance from point P6 to point P2. These distances are measured along the direction of the tangent line S1. The striking surface 10a has a point P7 between points P3 and P5. The distance from point P7 to point P5 is equal to the distance from point P7 to point P3. These distances are measured along the direction of the tangent line S1.

The area from point P2 to point P3 is the vertical center area F1. The upper area F2 from point P2 to point P4 and the lower area F3 from point P3 to point P5 are the vertical areas F4.

The longitudinal section is determined at each position in the toe-heel direction. At each position in the toe-heel direction, a vertical central region F1, an upper region F2, a lower region F3, and upper and lower regions F4 can be defined. Thus, these regions F1, F2, F3, and F4 can have widths in the toe-heel direction.

As shown in the horizontal-longitudinal cross section of Figure 20, the striking surface 10a has a cross-sectional center point P10. The cross-sectional center point P10 is a point located on the vertical axis Z2 when viewed from the front of the head (see Figure 3). Since Figure 20 is a center cross-sectional view, the cross-sectional center point P10 is the face center Fc.

In the cross section, the striking surface 10a has a tangent line S2 at the cross section center point P10. In FIG. 20, the tangent line S2 is shown by a two-dot chain line.

The striking surface 10a has a point P12 that is 20.0 mm away from the cross-sectional center point P10 on the toe side, and a point P13 that is 20.0 mm away from the cross-sectional center point P10 on the heel side. These 20.0 mm are measured along the direction of the tangent line S2. The striking surface 10a has a point P14 on the striking surface periphery k1 that is located on the toe side of point P12, and a point P15 on the striking surface periphery k1 that is located on the heel side of point P13. The striking surface 10a has a point P16 between points P12 and P14. The distance from point P16 to point P14 is equal to the distance from point P16 to point P12. These distances are measured along the direction of the tangent line S2. The striking surface 10a has a point P17 between points P13 and P15. The distance from point P17 to point P15 is equal to the distance from point P17 to point P13. These distances are measured along the direction of tangent line S21.

The area from point P12 to point P13 is the left-right central area G1. The toe side area G2 from point P12 to point P14 and the heel side area G3 from point P13 to point P15 are the left-right areas G4.

The cross section is determined at each position in the vertical direction. At each position in the vertical direction, a left-right central region G1, a toe side region G2, a heel side region G3, and left and right regions G4 can be defined. Therefore, these regions G1, G2, G3, and G4 can have widths in the vertical direction.

The roll radius of each region is determined by the longitudinal section illustrated in FIG. 19. The roll radius r1 of the vertical center region F1 is the radius of a circle passing through the three points P1, P2, and P3. The roll radius r4 of the vertical region F4 is the radius r2 of a circle passing through the three points P2, P4, and P6, and the radius r3 of a circle passing through the three points P3, P5, and P7. Radius r2 is the roll radius of the upper region F2. Radius r3 is the roll radius of the lower region F3.

The bulge radius of each region is determined by the cross section illustrated in FIG. 20. The bulge radius r5 of the left-right central region G1 is the radius of a circle passing through the three points P10, P12, and P13. The bulge radius r8 of the left-right region G4 is the radius r6 of a circle passing through the three points P12, P14, and P16, and the radius r7 of a circle passing through the three points P13, P15, and P17. Radius r6 is the bulge radius of the toe side region G2. Radius r7 is the bulge radius of the heel side region G3.

As shown in FIG. 19, the roll radius r4 of the upper and lower regions F4 is smaller than the roll radius r1 of the vertical central region F1. That is, the roll radius r2 of the upper region F2 is smaller than the roll radius r1 of the vertical central region F1, and the roll radius r3 of the lower region F3 is smaller than the roll radius r1 of the vertical central region F1.

As shown in FIG. 20, the bulge radius r8 of the left and right regions G4 is smaller than the bulge radius r5 of the left and right central region G1. In other words, the bulge radius r6 of the toe side region G2 is smaller than the bulge radius r5 of the left and right central region G1, and the bulge radius r7 of the heel side region G3 is smaller than the bulge radius r5 of the left and right central region G1.

[Inner surface shape near the face boundary]
All of the above-described embodiments have the following configuration at the boundary between the face portion 10 and the crown portion 12 and the boundary between the face portion 10 and the sole portion 14. This configuration will be described below with reference to FIG.

The center longitudinal section satisfies the following (a) and (b).
(a) When the boundary point between the inner surface of the crown portion 12 and the inner surface of the face portion 10 is the CF inner surface boundary point kc, the radius of curvature of the head inner surface at the CF inner surface boundary point kc is 6.0 mm or more and 10.0 mm or less. The head thickness t9 at the CF inner surface boundary point kc is 2.0 mm or more.
(b) When a point 10 mm away from the CF inner surface boundary point kc toward the crown side is defined as point C10, the head thickness gradually decreases from the CF inner surface boundary point kc to point C10. The head thickness t10 at point C10 is 1.0 mm or less.

Furthermore, the center longitudinal section satisfies the following (a1).
(a1) When a region of the head inner surface that is within 5 mm from the CF inner surface boundary point kc is defined as a CF boundary region X1, the radius of curvature of the head inner surface in the CF boundary region X1 is 6.0 mm or more and 10.0 mm or less.

Furthermore, the center longitudinal section satisfies the following (c) and (d).
(c) When the boundary point between the inner surface of the sole portion 14 and the inner surface of the face portion 10 is defined as the SF inner surface boundary point ks, the radius of curvature of the head inner surface at the SF inner surface boundary point ks is 7.0 mm or more and 11.0 mm or less. The head thickness t11 at the SF inner surface boundary point ks is 2.0 mm or more.
(d) When a point S15 is located 15 mm toward the sole side (back side) from the SF inner surface boundary point ks, the head thickness gradually decreases from the SF inner surface boundary point ks to the point S15. The head thickness t12 at the point S15 is 1.0 mm or less.

Furthermore, the center longitudinal section satisfies the following (c1).
(c1) When a region within 5 mm from the SF inner surface boundary point ks is defined as the SF boundary region X2, the radius of curvature of the head inner surface in the SF boundary region X2 is 7.0 mm or more and 11.0 mm or less.

In the above configurations (a) to (d), (a1) and (c1), each distance is the distance along the cross-sectional line of the head inner surface. In the above configurations (a) to (d), (a1) and (c1), the radius of curvature of a certain point is the radius of a circle that passes through three points: that point, a point 1 mm away on one side of that point, and a point 1 mm away on the other side of that point. These "1 mm" are the distance along the cross-sectional line of the head inner surface. In addition, the CF inner surface boundary point kc and the SF inner surface boundary point ks are the intersection points of the normal to the outer surface of the head at the striking face periphery k1 and the head inner surface. The above configurations (a) to (d), (a1) and (c1) may be satisfied in other longitudinal sections that are different in the toe-heel direction from the center longitudinal section. From the viewpoint of resilience performance, it is preferable that one or more selected from the group consisting of the above configurations (a) to (d), (a1), and (c1) are satisfied in the center vertical section, more preferably in every vertical section from 5 mm on the toe side of the face center Fc to 5 mm on the heel side, more preferably in every vertical section from 10 mm on the toe side of the face center Fc to 10 mm on the heel side, more preferably in every vertical section from 15 mm on the toe side of the face center Fc to 15 mm on the heel side, and more preferably in every vertical section from 20 mm on the toe side of the face center Fc to 20 mm on the heel side.

In this configuration, the boundary area between the face portion 10 and the body side portion (crown portion 12, sole portion 14) is rounded and the boundary is thickened. Therefore, when the ball is struck, the boundary area does not become a bending point, and the deformation of the face portion is transmitted to the body side. As a result, the starting point of bending can be moved toward the body side, and the body portion can be flexed efficiently. The bending of the body portion amplifies the bending of the face portion, improving the repulsion performance.

[Action and Effect]
The above-described embodiments provide the following advantages.

In all of the embodiments, the thickness distribution increases durability while expanding local deformation in the vertical direction near the face center. This expands the high-repulsion area in the vertical direction, improving the flight distance for golfers who adjust the impact point in the vertical direction to hit different trajectories. In addition, structures such as the above configurations (a) to (d) amplify the deflection of the face portion due to the deflection of the body portion, improving the repulsion performance.

In the third and fourth embodiments, a rounded shape is used on the toe side. This rounded shape brings the extension direction of the face part's cross section on the toe side closer to the normal direction of the striking surface, thereby increasing the rigidity of the face part when hitting on the toe side. As a result, durability is further improved. In the third and fourth embodiments, a rounded shape of the bulge and roll is used on the periphery of the striking surface. This rounded shape brings the extension direction of the face part on the periphery of the striking surface closer to the normal direction of the striking surface, thereby increasing the rigidity of the face part when hitting on the periphery of the striking surface. As a result, durability is further improved. In the fourth embodiment, the front part of the crown is made thin. This thin part improves the repulsion performance at the upper impact point.

As mentioned above, the longitudinal section is set at each position in the toe-heel direction. The rounded shape of the roll around the ball-striking surface as described above spreads in the toe-heel direction, thereby further increasing durability. From this perspective, the rounded shape of the roll is preferably satisfied at the center longitudinal section, more preferably at all longitudinal sections from 5 mm to the toe side of the face center Fc to 5 mm to the heel side, more preferably at all longitudinal sections from 10 mm to the toe side of the face center Fc to 10 mm to the heel side, more preferably at all longitudinal sections from 15 mm to the toe side of the face center Fc to 15 mm to the heel side, and more preferably at all longitudinal sections from 20 mm to the toe side of the face center Fc to 20 mm to the heel side.

As mentioned above, the cross section is set at each position in the vertical direction. The rounded shape of the bulge around the ball-striking surface expands in the vertical direction, which further increases durability. From this perspective, the rounded shape of the bulge is preferably satisfied in the center cross section, more preferably in all cross sections from 5 mm above the face center Fc to 5 mm below, more preferably in all cross sections from 10 mm above the face center Fc to 10 mm below, and even more preferably in all cross sections from 15 mm above the face center Fc to 15 mm below.

As mentioned above, the vertical section is set at each position in the toe-heel direction. The above-mentioned structure in which the front part of the crown is made thin-walled expands in the toe-heel direction, thereby further improving the resilience performance in upward hits. From this perspective, the structure in which the front part of the crown is made thin-walled is preferably satisfied in the center vertical section, more preferably in all vertical sections from 5 mm on the toe side of the face center Fc to 5 mm on the heel side, more preferably in all vertical sections from 10 mm on the toe side of the face center Fc to 10 mm on the heel side, and more preferably in all vertical sections from 15 mm on the toe side to 15 mm on the heel side.

The following describes examples of the present invention. However, the present invention is not limited to these specific examples.

[Example 1]
The same head as the head 4 of the first embodiment was produced. The volume of the head 4 was 460 ^cm3 . The central constant thickness tc was 2.75 mm. The first peripheral constant thickness t1 was 3.10 mm. The second peripheral constant thickness t2 was 2.10 mm. The first transitional thickness t3 was continuously increased from 2.75 mm to 3.10 mm toward the face periphery. The second transitional thickness t4 was continuously decreased from 2.75 mm to 2.10 mm toward the face periphery. The third peripheral thickness t5 was 2.50 mm in the crown side region 29c and 2.30 mm in the sole side region 29s. The specifications of this Example 1 are shown in Table 1 below.

[Example 2]
A head identical to the head 42 of the second embodiment was produced. That is, the head of Example 2 was obtained in the same manner as Example 1 except that the thickness t5 of the third peripheral portion was increased. The thickness t5 of the third peripheral portion 28 was 3.10 mm in the crown side region 29c and 2.90 mm in the sole side region 29s. The specifications of Example 2 are shown in Table 1 below.

[Example 3]
A head identical to the head 43 of the third embodiment was produced. That is, the head of Example 3 was produced in the same manner as Example 1 except for the rounded shape of the toe side and the rounded shape of the bulge and roll around the periphery of the ball-striking face. The specifications of Example 3 are shown in Table 1 below.

[Example 4]
A head identical to the head 44 of the fourth embodiment was produced. That is, the head of Example 4 was obtained in the same manner as Example 3 except for the thinning of the front part of the crown. The specifications of Example 4 are shown in Table 1 below.

[Comparative Example 1]
FIG. 21 is a front view of the head 50 of Comparative Example 1, and FIG. 22 is the same front view as FIG. 21. In FIG. 22, the lines dividing the regions of the face portion are shown by dashed lines. The face portion 10 of the head 50 is composed of a central portion 52 including a face center Fc, a transition portion 54 continuously surrounding the outside of the central portion 52, and a peripheral portion 56 continuously surrounding the outside of the transition portion 54. The central portion 52 has a contour line k5. The inner contour line k6 of the transition portion 54 coincides with the contour line k5 of the central portion 52. The outer contour line k7 of the transition portion 54 has a point 58 that intersects with the periphery k3 of the face member 4b. The inner contour line k8 of the peripheral portion 56 coincides with the contour line k7. The outer contour line k9 of the peripheral portion 56 coincides with the periphery k1 of the striking surface 10a. The central portion 52 has a constant thickness. The thickness of the central portion 52 is 3.48 mm. The peripheral portion 56 has a constant thickness. The thickness of the peripheral portion 56 is 2.23 mm. The thickness of the transition portion 54 decreases continuously from 3.48 mm to 2.23 mm toward the periphery of the face. Aside from the thickness distribution described above, the head of Comparative Example 1 was obtained in the same manner as in Example 1. The specifications of Comparative Example 1 are shown in Table 1 below.

For each example and comparative example, the above-mentioned W1/W2, distance W3, roll radius r1 of the vertical center region F1, roll radius r2 of the upper region F2, roll radius r3 of the lower region F3, bulge radius r5 of the horizontal center region G1, bulge radius r6 of the toe side region G2, and bulge radius r7 of the heel side region G3 are shown in Table 1 below.

As shown in Table 1, in the heads in which the rounded shape on the toe side is applied (Examples 2 and 3), W1/W2 is small. In addition, in the heads in which the rounded shape on the periphery of the ball-striking surface is applied (Examples 2 and 3), the roll radius r2 of the upper region and the roll radius r3 of the lower region are smaller than the roll radius r1 of the vertical center region, and the bulge radius r6 of the toe side region and the bulge radius r7 of the heel side region are smaller than the bulge radius r5 of the horizontal center region.

The COR was evaluated for Examples 2 to 4 and Comparative Example 1. The evaluation method was as follows.

[COR]
COR means the coefficient of restitution. The COR was measured based on the "Interim Procedure for Measuring the Coefficient of Restitution of an Iron Clubhead Relative to a Baseline Plate Revision 1.3 January 1, 2006" prescribed by the USGA (United States Golf Association). Measurement points were set at 5 mm intervals in the vertical direction and the toe-heel direction, including the face center Fc. The evaluation values at impact points above and below the face center Fc were calculated as the average of the measurement value at the impact point, the measurement value at a point 5 mm to the toe side, and the measurement value at a point 5 mm to the heel side. For example, in determining the evaluation value at a point 5 mm above the face center Fc, the measurement value at the point 5 mm above, the measurement value at a point 5 mm away from the point 5 mm above on the toe side, and the measurement value at a point 5 mm away from the point 5 mm above on the heel side were used, and the average of these three measurement values was adopted. The evaluation values at impact points on the toe and heel sides of the face center Fc were calculated as the average of the measurement value at the impact point, the measurement value at a point 5 mm above, and the measurement value at a point 5 mm below. For example, in determining the evaluation value at 5 mm to the toe side of the face center Fc, the measurement value at the point 5 mm to the toe side, the measurement value at the point 5 mm above the point 5 mm toe side, and the measurement value at the point 5 mm below the point 5 mm toe side were used, and the average value of these three measurement values was adopted. The evaluation value of Comparative Example 1 was set to 100, and the evaluation value at each point was indexed. This index is shown in Table 2 below. The evaluation value (index) at the face center Fc is shown in the column "COR (face center Fc)". The evaluation value (index) at the point 5 mm above the face center Fc is shown in the column "COR (upper 5 mm)". The evaluation value (index) at the point 5 mm below the face center Fc is shown in the column "COR (lower 5 mm)". The evaluation value (index) at the point 10 mm above the face center Fc is shown in the column "COR (upper 10 mm)". The evaluation value (index) at a point 10 mm below the face center Fc is shown in the "COR (lower 10 mm)" column. The evaluation value (index) at a point 5 mm to the toe side from the face center Fc is shown in the "COR (toe 5 mm)" column. The evaluation value (index) at a point 5 mm to the heel side from the face center Fc is shown in the "COR (heel 5 mm)" column. The evaluation value (index) at a point 10 mm to the toe side from the face center Fc is shown in the "COR (toe 10 mm)" column. The evaluation value (index) at a point 10 mm to the heel side from the face center Fc is shown in the "COR (heel 10 mm)" column.

The durability performance was evaluated for Examples 2 and 3 and Comparative Example 1. The evaluation method was as follows.

[Durability]
The club was attached to a swing robot, and the two-piece ball was hit at a head speed of 54 m/s. The impact point was set to the face center Fc. The face surface was inspected in detail every 50 hits to check for damage such as cracks. The hitting was stopped when damage was found. If no damage occurred after 5000 hits, the hitting was stopped at 5000 hits.

In all of Example 2, Example 3, and Comparative Example 1, no damage occurred after 5,000 strikes. It was confirmed that Examples 2 and 3 have the same durability as Comparative Example 1.

As shown in Tables 1 and 2, the advantages of the present invention are clear.

The following notes are part of the invention described herein:
[Appendix 1]
A golf club head having a hollow portion therein,
The golf club has a face portion having a striking surface, a crown portion, and a sole portion,
The face portion has a face main portion including a face center,
the face main portion includes a central portion including the face center, a transition portion formed outside the central portion, and a peripheral portion formed outside the transition portion,
the peripheral portion includes a first peripheral portion formed on each of a toe side and a heel side of the face main portion, and a second peripheral portion formed on each of a crown side and a sole side of the face main portion,
the transition portion includes a first transition portion located between the central portion and the first peripheral portion, and a second transition portion located between the central portion and the second peripheral portion,
The central portion has a constant central thickness and a surface area of 100 ^mm2 or more;
the first peripheral portion has a first peripheral constant thickness, the first peripheral constant thickness being greater than the central constant thickness;
the second peripheral portion has a second peripheral constant thickness, the second peripheral constant thickness being less than the central constant thickness;
the thickness of the first transition portion increases from the central constant thickness to the first peripheral constant thickness;
The golf club head, wherein the thickness of the second transition portion decreases from the central constant thickness to the second peripheral constant thickness.
[Appendix 2]
The face portion further includes a third peripheral portion on an outer side of the face main portion,
The third peripheral portion surrounds the face main portion continuously or intermittently,
2. The golf club head according to claim 1, wherein the thickness of the third peripheral portion is greater than the constant thickness of the central portion.
[Appendix 3]
The face portion further includes a third peripheral portion on an outer side of the face main portion,
The third peripheral portion surrounds the face main portion continuously or intermittently,
2. The golf club head according to claim 1, wherein the thickness of the third peripheral portion is smaller than the constant thickness of the central portion.
[Appendix 4]
4. The golf club head according to claim 2, wherein the third periphery portion continuously surrounds the face main portion.
[Appendix 5]
The third peripheral portion is
a crown side third peripheral portion connected to at least one selected from the group consisting of the first peripheral portion, the second peripheral portion, the first transition portion, and the second transition portion on the crown side;
a sole-side third peripheral portion connected to at least one selected from the group consisting of the first peripheral portion, the second peripheral portion, the first transition portion, and the second transition portion, on the sole side;
Contains
5. The golf club head according to claim 2, wherein the thickness of the sole-side third peripheral portion is smaller than the thickness of the crown-side third peripheral portion.
[Appendix 6]
The third peripheral portion is
a toe peripheral transition portion connected to a toe side and at least one selected from the group consisting of the first peripheral portion, the second peripheral portion, the first transition portion, and the second transition portion;
a heel periphery transition portion connected to at least one selected from the group consisting of the first periphery portion, the second periphery portion, the first transition portion, and the second transition portion on a heel side;
a crown side region connected to the toe peripheral transition portion and the heel peripheral transition portion on a crown side;
a sole side region that is continuous with the toe periphery transition portion and the heel periphery transition portion to a sole side;
Contains
the thickness of the toe peripheral transition portion is smaller than the thickness of the crown side region;
6. The golf club head according to claim 2, wherein the thickness of the heel peripheral transition portion is smaller than the thickness of the crown side region.
[Appendix 7]
The face portion further includes a third transition portion extending along a line inclined at ±20 to ±70 degrees with respect to a parallel axis extending in a toe-heel direction and passing through the face center,
7. The golf club head according to claim 1, wherein the third transition portion is located between at least one of the first perimeter portion and the first transition portion and at least one of the second perimeter portion and the second transition portion.
[Appendix 8]
7. The golf club head according to any one of claims 2 to 6, wherein the second periphery has a width of 1.0 mm or more and 7.0 mm or less relative to a boundary line between the second periphery and the third periphery.
[Appendix 9]
8. The golf club head according to claim 7, wherein the third transition portion has a width of 1.0 mm or more and 7.0 mm or less.
[Appendix 10]
10. The golf club head according to claim 1, wherein the surface area of the central portion is 5% to 15% of the area of the striking face.
[Appendix 11]
The first periphery includes a toe side first periphery and a heel side first periphery,
a surface area of the toe side first peripheral portion is 1% or more and 9% or less of an area of the striking surface;
11. The golf club head according to claim 1, wherein the surface area of the heel-side first peripheral portion is 1% or more and 9% or less of the area of the striking face.
[Appendix 12]
The second periphery includes a crown side second periphery and a sole side second periphery,
a surface area of the crown-side second peripheral portion is equal to or greater than 1% and equal to or less than 7% of an area of the striking face,
12. The golf club head according to claim 1, wherein the surface area of the sole-side second peripheral portion is 1% to 7% of the area of the striking face.
[Appendix 13]
13. The golf club head according to any one of claims 1 to 12, wherein the central portion has a contour that is longer in a toe-heel direction than in a vertical direction.
[Appendix 14]
14. The golf club head according to claim 1, wherein the central constant thickness of the central portion is 2.5 mm or greater and 3.0 mm or less.
[Appendix 15]
15. The golf club head according to any one of claims 1 to 14, wherein the first peripheral constant thickness of the first peripheral portion is 2.8 mm or more and 3.4 mm or less.
[Appendix 16]
16. The golf club head according to claim 1, wherein the second peripheral constant thickness of the second peripheral portion is 1.8 mm or greater and 2.4 mm or less.
[Appendix 17]
7. The golf club head according to claim 2, wherein the third peripheral portion has a thickness of 2.1 mm or more and 3.3 mm or less.
[Appendix 18]
When a parallel axis passing through the face center and extending in a toe-heel direction and a vertical axis passing through the face center and extending in a vertical direction are defined,
In the face portion, the roll radius of upper and lower regions each separated by 7.5 mm or more from the parallel axis on the upper and lower sides is smaller than the roll radius of a vertical center region within 7.5 mm from the parallel axis,
18. The golf club head according to any one of claims 1 to 17, wherein in the face portion, the bulge radius of left and right regions that are 20.0 mm or more away from the vertical axis on the toe side and heel side, respectively, is smaller than the bulge radius of a left-right central region that is within 20.0 mm from the vertical axis.

2: Golf club 4, 42, 43, 44, 50: Head 10: Face portion 10a: Striking surface 12: Crown portion 12a: Crown front portion 14: Sole portion 20: Face main portion 22: Central portion 24: Transition portion 241: First transition portion 24t: Toe side first transition portion 24h: Heel side first transition portion 242: Second transition portion 24c: Crown side second transition portion 24s: Sole side second transition portion 26: Peripheral portion 261: First peripheral portion 26t: Toe side first peripheral portion 26h: Heel side first peripheral portion 262: Second peripheral portion 26c: Crown side second peripheral portion 26s: Sole side second peripheral portion 28: Third peripheral portion 28t: Toe side third peripheral portion 28h: Heel side third peripheral portion 28c: crown side third peripheral portion 28s: sole side third peripheral portion 29a: peripheral transition portion 29t: toe peripheral transition portion 29h: heel peripheral transition portion 29c: crown side region 29s: sole side region 30: third transition portion 301: toe upper third transition portion 302: heel upper third transition portion 303: heel lower third transition portion 304: toe lower third transition portion Fc: face center F1: vertical central region F2: upper region F3: lower region F4: vertical region G1: horizontal central region G2: toe side region G3: heel side region G4: horizontal region k1: periphery of striking surface SS: sweet spot

Claims (18)

A golf club head having a hollow portion therein,
The golf club has a face portion having a striking surface, a crown portion, and a sole portion,
The face portion has a face main portion including a face center,
the face main portion includes a central portion including the face center, a transition portion formed outside the central portion, and a peripheral portion formed outside the transition portion,
the peripheral portion includes a first peripheral portion formed on each of a toe side and a heel side of the face main portion, and a second peripheral portion formed on each of a crown side and a sole side of the face main portion,
the transition portion includes a first transition portion located between the central portion and the first peripheral portion, and a second transition portion located between the central portion and the second peripheral portion,
The central portion has a constant central thickness and a surface area of 100 ^mm2 or more;
the first peripheral portion has a first peripheral constant thickness, the first peripheral constant thickness being greater than the central constant thickness;
the second peripheral portion has a second peripheral constant thickness, the second peripheral constant thickness being less than the central constant thickness;
the thickness of the first transition portion increases from the central constant thickness to the first peripheral constant thickness;
The golf club head, wherein the thickness of the second transition portion decreases from the central constant thickness to the second peripheral constant thickness. The face portion further includes a third peripheral portion on an outer side of the face main portion,
The third peripheral portion surrounds the face main portion continuously or intermittently,
2. The golf club head according to claim 1, wherein the thickness of the third peripheral portion is greater than the constant thickness of the central portion. The face portion further includes a third peripheral portion on an outer side of the face main portion,
The third peripheral portion surrounds the face main portion continuously or intermittently,
2. The golf club head according to claim 1, wherein the thickness of the third peripheral portion is smaller than the constant thickness of the central portion. The golf club head according to claim 2 or 3, wherein the third peripheral portion continuously surrounds the main face portion. The third peripheral portion is
a crown side third peripheral portion connected to at least one selected from the group consisting of the first peripheral portion, the second peripheral portion, the first transition portion, and the second transition portion on the crown side;
a sole-side third peripheral portion connected to at least one selected from the group consisting of the first peripheral portion, the second peripheral portion, the first transition portion, and the second transition portion, on the sole side;
Contains
4. The golf club head according to claim 2, wherein the thickness of the sole-side third peripheral portion is smaller than the thickness of the crown-side third peripheral portion. The third peripheral portion is
a toe peripheral transition portion connected to a toe side and at least one selected from the group consisting of the first peripheral portion, the second peripheral portion, the first transition portion, and the second transition portion;
a heel periphery transition portion connected to at least one selected from the group consisting of the first periphery portion, the second periphery portion, the first transition portion, and the second transition portion on a heel side;
a crown side region connected to the toe peripheral transition portion and the heel peripheral transition portion on a crown side;
a sole side region that is continuous with the toe periphery transition portion and the heel periphery transition portion to a sole side;
Contains
the thickness of the toe peripheral transition portion is smaller than the thickness of the crown side region;
4. The golf club head according to claim 2, wherein the thickness of the heel transition portion is smaller than the thickness of the crown side region. The face portion further includes a third transition portion extending along a line inclined at ±20 to ±70 degrees with respect to a parallel axis extending in a toe-heel direction and passing through the face center,
The golf club head of claim 1 , wherein the third transition portion is located between at least one of the first perimeter and the first transition portion and at least one of the second perimeter and the second transition portion. The golf club head according to claim 2 or 3, wherein the second peripheral portion has a width of 1.0 mm or more and 7.0 mm or less relative to the boundary line between the second peripheral portion and the third peripheral portion. The golf club head according to claim 7, wherein the width of the third transition portion is 1.0 mm or more and 7.0 mm or less. The golf club head according to claim 1, wherein the surface area of the central portion is 5% to 15% of the area of the striking surface. The first periphery includes a toe side first periphery and a heel side first periphery,
a surface area of the toe side first peripheral portion is 1% or more and 9% or less of an area of the striking surface;
2. The golf club head according to claim 1, wherein the surface area of the heel-side first peripheral portion is equal to or greater than 1% and equal to or less than 9% of the area of the striking face. The second periphery includes a crown side second periphery and a sole side second periphery,
a surface area of the crown-side second peripheral portion is equal to or greater than 1% and equal to or less than 7% of an area of the striking face,
2. The golf club head according to claim 1, wherein the surface area of the second peripheral portion on the sole side is equal to or greater than 1% and equal to or less than 7% of the area of the striking face. The golf club head according to claim 1, wherein the central portion has a contour that is longer in the toe-heel direction than in the up-down direction. The golf club head according to claim 1, wherein the central constant thickness of the central portion is 2.5 mm or more and 3.0 mm or less. The golf club head according to claim 1, wherein the first peripheral constant thickness of the first peripheral portion is 2.8 mm or more and 3.4 mm or less. The golf club head according to claim 1, wherein the second peripheral constant thickness of the second peripheral portion is 1.8 mm or more and 2.4 mm or less. The golf club head according to claim 2 or 3, wherein the thickness of the third peripheral portion is 2.1 mm or more and 3.3 mm or less. When a parallel axis passing through the face center and extending in a toe-heel direction and a vertical axis passing through the face center and extending in a vertical direction are defined,
In the face portion, the roll radius of upper and lower regions each separated by 7.5 mm or more from the parallel axis on the upper and lower sides is smaller than the roll radius of a vertical center region within 7.5 mm from the parallel axis,
4. The golf club head according to claim 1, wherein the bulge radius of the face portion in left and right regions that are 20.0 mm or more away from the vertical axis on the toe side and heel side, respectively, is smaller than the bulge radius of a left-right central region that is within 20.0 mm from the vertical axis.

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