JP3510143B2 - Cylindrical member with drag reduction function - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical member having a drag reducing function, and particularly to a cylindrical member such as a shaft of a golf club that is moved in the air at a high speed in the traveling direction, or around a circumferential surface. The present invention relates to a columnar member with a drag reducing function capable of reducing a shape drag (pressure resistance) depending on the shape of an object in a columnar member in which a fluid may flow in a fixed direction.

[0002]

2. Description of the Related Art For example, when a golf club is shaken in the air, the air around the golf club changes with the movement of the golf club. That is, when the golf club is assumed to be in a fixed state, the surrounding air flows in a fixed direction relative to the golf club. When the velocity of the flowing air is relatively slow, such as when the golf club is slowly moved, the air flow around the shaft is symmetrical in the front-rear direction and shows a streamline pattern. However, when the velocity of the flowing air is relatively high, such as when the golf club is moved at a high speed, the air flow begins to separate from the rear side of the shaft, and the twin-vortex reflow with backflow occurs downstream of the shaft. A circulation region is formed. Furthermore, when the flow velocity of air is high, the vortices cannot be stably attached to the shaft, and vortices whose rotation directions are opposite to each other alternately and periodically leave the shaft and flow to the downstream side. Form a row (Karman's vortex street). Therefore, a force acts in the direction opposite to the traveling direction of the shaft, and the shape drag force (pressure resistance) increases.

When a Karman vortex street occurs, the flow around the shaft changes periodically in response to it. In other words, the circulation around the shaft changes with the periodic discharge of the vortices. Therefore, a periodic lift is generated on the shaft, and the shaft is subjected to forced vibration. Therefore, when the shaft is moved rapidly such as downswing, the shaft has a meandering motion and impairs straightness. In addition,
These inconveniences occur not only in the shaft of the golf club but also in the bat, the fishing rod, and the like.

Therefore, the inventors of the present invention have devised a shaft having a plurality of convex portions formed on the surface thereof (for example, Japanese Patent Laid-Open No. 9-299526). This is to prevent the relative flow of air from being agitated and diffused by the convex portion formed on the surface and to prevent the air flow from going around to the back side of the shaft to generate a Karman vortex.

[0005]

However, as a result of repeating the experiment, the above-mentioned configuration may not be able to obtain a remarkable effect. That is, in the above, a plurality of convex portions were formed over the entire circumferential surface. Therefore, even if a convex portion is formed in the region from the tip to the left and right sides with the point (line) on the circumferential surface facing the wind flow direction as the tip, the generation of Karman vortices can be suppressed. However, since the air resistance may increase due to the formation of the convex portion, the shape drag cannot be extremely reduced as a result.

Therefore, the present invention is based on the shape drag force (pressure resistance).
It is an object of the present invention to provide a columnar member with a drag reducing function capable of reliably reducing the force.

[0007]

According to a first aspect of the present invention, there is provided a columnar member having a drag reducing function, wherein a convex portion for reducing a shape drag is provided on a circumferential surface of the column member having a drag reducing function. The parts are provided at symmetrical positions on the circumferential surface with the tip on the circumferential surface facing the flow direction of the fluid as the center, and the circumferential surface with the tip as a reference (0 °).
Starting point forming position of the convex portion, which starts forming the convex portion above
Is within a range of more than 90 ° and 125 ° or less .

Here, examples of the columnar member include a golf club shaft, a bat, and a fishing rod. In other words, the object is to move in a certain direction in the fluid, or conversely, the fluid flows in a certain direction around the circumferential surface.
The protrusion may be integrally formed with the columnar member, or may be formed by plating, painting, painting, silk printing, plate-making printing, rust, or the like. You may form by adhering the formed sheet to a cylindrical member. Also, as the shape of the cylindrical member,
The outer diameter (cross-sectional area) may be the same from the base to the tip, and the taper shape in which the outer diameter (cross-sectional area) gradually decreases toward the tip, or the outer diameter (cross-sectional area) extends toward the tip It may have a tapered shape that gradually increases.

Therefore, according to the columnar member with the drag reducing function of the first aspect of the invention, the shape drag can be reduced by the convex portion formed at the predetermined angle position of the columnar member. More specifically, in the case where the convex portion is not formed, the boundary layer separates in a laminar flow state, so that the downstream side of the columnar member is in a constant negative pressure state. On the other hand, by forming a convex portion at a predetermined angle position on the cylindrical member, the boundary layer transitions from the laminar flow state to the turbulent flow state, and the separation point moves downstream. That is, by delaying the separation to the downstream side, the asymmetry of the pressure distribution is alleviated, and the shape drag is reduced.

Then, the tip on the circumferential surface is used as a reference point, and an area of 90 ° or less from the reference point (180 degrees around the reference point)
Since the convex portion is not formed in the area within °, the air resistance does not increase due to the convex portion. This reduces the form drag force.

According to a second aspect of the present invention, there is provided a columnar member with a drag reducing function, wherein in the columnar member with a drag reducing function according to the first aspect, the diameter is 10 m when the tip is 0 °.
When the protrusion height of the convex portion is 0.0125 times the diameter of the column member with respect to the column member of m, the starting end forming position is set.
If the position is within the range of 91 ° to 93 °, 0.0175 times
The starting end forming position is within the range of 91 ° to 96 °, and is 0.02
In the case of 5 times, the starting end forming position is within the range of 96 ° to 103 °, and in the case of 0.05 times, the starting end forming position is 102 °.
The relationship that the difference in angle between the tip and the start end forming position on the circumferential surface is increased as the protrusion height of the protrusion with respect to the diameter of the columnar member is increased so as to fall within a range of up to 117 °. Based on the above, the protrusion height of the convex portion and the starting end forming position are determined.

The inventors set the protrusion height of the protrusion and the formation position of the protrusion based on a predetermined relationship,
It was found based on experiments that the form drag of the columnar member is surely reduced. This predetermined relationship means that the higher the protrusion height of the convex portion, the larger the relative angle with respect to the reference point,
In other words, the higher the protrusion height of the convex portion, the closer the formation position of the convex portion is to the rear side. Specifically, for example, in the case of a shaft having a diameter of 10 mm, if the protrusion height of the protrusion is 0.125 mm, the angle is 91 ° with respect to the reference point.
In the case of forming a convex portion within a range of up to 93 °, and similarly, when the protruding height of the convex portion is set to 0.175 mm, within a range of 91 ° to 96 °, and in the case of setting it to 0.25 mm. 96 ° ~ 1
Within the range of 03 °, if it is 0.5 mm, 102 ° ~
It is formed within the range of 117 °.

Therefore, by setting the protruding height and the position of the convex portion based on the above relation, when the boundary layer separates, a turbulent flow state is surely established and the separation point moves to the downstream side. Moreover, since the increase in air resistance due to the convex portion is suppressed to a minimum, the form drag is surely reduced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A case in which a cylindrical member with a drag reducing function is applied to a shaft of a golf club will be described below as an embodiment of the present invention with reference to FIGS. 1 to 8. FIG. 1 is a perspective view showing the structure of a golf club,
2 is a perspective view of an essential part of the golf club shaft, FIG. 3 is a cross-sectional view showing a cross section of the golf club shaft, and FIGS. 4 to 7 show the relationship between the convex portion of the shaft and the drag coefficient. It is data and a graph shown. As shown in FIG. 1, a golf club 1 according to an embodiment of the present invention includes a grip 2, a head 3, and a shaft 4. The grip 2 is a part that is held by both hands when swinging the golf club 1, and is made of a material such as leather or rubber. The head 3 is the head of the golf club 1 and is made of a material such as wood or aluminum.

The shaft 4 is a long handle of a golf club and corresponds to the columnar member with a drag reducing function of the present invention.
The shaft 4 is made of a material such as steel, glass fiber, and aluminum, and has a substantially cylindrical rod-like appearance as shown in FIGS. 2 and 3. Specifically, the shaft 4 is a tapered columnar member having an outer diameter on the grip 2 side (for example, 14 mm) as the maximum diameter and an outer diameter on the head 3 side (for example, 8.5 mm) as the minimum diameter. The outer diameter near the center of 4 is about 10 mm. 2 and 3, an arrow A indicated by a dotted line indicates a moving direction of the shaft 4, specifically, a moving direction of the shaft 4 during a swing-down process (down swing) from the top of the takeback to the impact. Shows. That is, as shown in FIG. 3, the downswing is performed with the point P on the circumferential surface as the tip in the traveling direction.

Thus, in the air, the shaft 4 is moved to the arrow A
When moved in the direction of, the air around the shaft 4 becomes
It flows in a fixed direction relative to the shaft 4. That is, the air relatively flows in the direction opposite to the arrow A and faces the point P on the circumferential surface of the shaft 4. The circumferential surface of the shaft 4 is a smooth surface as a whole, but with the point P, which is the tip, as a reference point (0 °), two strip-shaped convex portions 5 are provided at positions corresponding to the left and right rear sides. 5b are juxtaposed.

Here, changes in the shape drag force when the shape of the convex portion 5 and the formation position of the convex portion 5 are changed are shown in FIGS. This data is based on the results of a wind tunnel experiment conducted in cooperation with the Japan Building Research Institute. In the experiment, the drag was measured using an enlarged model having a diameter four times that of the shaft 4, but the data shown in FIGS. 4 to 8 are converted so as to correspond to the actual shaft 4. is there. As an experimental method, after the enlarged model was attached to the wind tunnel balance (load detector), the wind speed was 10 m / s (the wind speed was assumed assuming that the moving speed of the head 3 was 40 m / s).
Is applied to measure the drag.

First, FIG. 4 shows the value of the drag coefficient when the height H of the convex portion 5 and the starting end forming position θ at which the convex portion 5 having a circular cross section is formed are changed with respect to the point P. It is a thing. Specifically, the height H is 0.125, 0.175, 0.25, or 0.5 with respect to the shaft 4 having a diameter of 10 mm.
The protrusion 5 of mm has a starting point forming position θ of 90 ° to 125 °.
The coefficient of drag is shown when it is formed so as to come to a predetermined position within the range. The drag coefficient is a coefficient for obtaining the shape drag (pressure resistance), and the smaller the value of the drag coefficient, the smaller the shape drag. That is, the shape drag can be reduced by reducing the drag coefficient. FIG. 5 shows a case where the height H of the convex portion 5 is 0.125 mm (shown in (a)), 0.175 mm (shown in (b)), 0.25 mm (shown in (c)), 0. 5m
6 is a graph showing the relationship between the starting point formation position θ and the drag coefficient in the case of m (shown in D).

The following can be seen from FIGS. 4 and 5. That is, when the height H of the convex portion 5 or the starting end forming position θ changes, the drag coefficient greatly changes. When the starting point formation position θ of the convex portion 5 is 90 ° or less, the drag coefficient greatly increases.
When the height H of the convex portion 5 is high, the drag coefficient can be reduced by increasing the starting end forming position θ of the convex portion 5. That is, there is a correlation between the height H of the convex portion 5 and the starting point formation position θ that can reduce the drag coefficient.

For example, the height H of the convex portion 5 is 0.25 mm
In the case of (shown in C), the starting point formation position θ is 96 ° to 1
The optimum value is in the range of 03 °, the drag coefficient greatly increases when it is smaller than 96 °, and the drag coefficient becomes a substantially constant value when it exceeds 103 °. Then, if such a tendency, that is, if it is less than or equal to the predetermined first angle, the drag coefficient increases,
The tendency that the drag coefficient becomes substantially constant when the angle is equal to or greater than the predetermined second angle similarly occurs even if the protrusion height of the convex portion 5 changes.
The values of the first angle and the second angle, that is, the optimum range of the starting end forming position θ changes depending on the protruding height of the convex portion 5.
Specifically, the optimum range of the starting end forming position θ is 91 ° when the height H of the convex portion 5 is 0.125 mm (shown in (a)).
When the height H of the convex portion 5 is 0.175 mm (shown in B), it becomes 91 ° to 96 ° and the height H of the convex portion 5 is 0.5 mm (shown in D). In case of 102 °
It becomes ~ 117 °.

FIG. 6 (a) is experimental data showing changes in the drag coefficient when the circumferential width L of the convex portion 5 is changed, and FIG. 6 (b) is a graph showing the experimental data. It was done. Specifically, with respect to the shaft 4 having a diameter of 10 mm, the protrusion 5 having the height H of 0.25 mm is formed at the starting end forming position θ.
In the position where the angle is 100 °, the convex portion 5
The width L in the circumferential direction is changed from 0.5 mm to 0.15 mm. From this experimental result, the width L in the circumferential direction of the convex portion 5 does not significantly affect the drag coefficient, but if the width L is too short, the effect of delaying the peeling point rearward decreases, so The coefficient tends to increase. In the shaft 4 having a diameter of 10 mm, the width L is optimally a length between 0.75 and 1.00 mm.

FIG. 7 is experimental data showing changes in the drag coefficient when two convex portions 5 are formed. Specifically, FIG.
(A) is a convex portion 5 (1
The first convex portion) is formed at the position where the starting point forming position θ is 100 °, and the convex portion 5b (second convex part) having the same diameter of 0.25 mm is formed at the starting point forming position α of 130 °.
It is a drag coefficient when it is changed from to 140 °.
Further, in FIG. 7B, the height H is 0.25 mm and the width L is 1 mm, and the convex portion 5 (first convex portion) having a substantially rectangular cross section is located at the position where the starting point forming position θ is 100 °. In the formed product, the height H is 0.25 mm and the width L is 1.
The 0 mm convex portion 5b (the second convex portion) is set to the starting end forming position α.
Is a drag coefficient when the value is varied between 130 ° and 140 °. 7 (a) and 7 (b) also show, for comparison, the drag coefficient when the number of the convex portions 5 is one. From these experimental results, it is possible to reduce the drag coefficient by increasing the number of the convex portions 5 from 1 to 2, but
When the starting point formation position α of the second convex portion 5b is larger than a predetermined value, in other words, the second convex portion 5b is the first convex portion 5
If it is too far from, the drag coefficient tends to increase.

Based on the above experimental results, the shaft 4 of the golf club 1 of this embodiment has a height H of 0.25 mm.
And the convex portion 5 (first convex portion) having a substantially rectangular cross section with a width L of 1.0 mm is formed at a position where the starting end forming position θ is 100 °, and the convex portion 5b (second convex portion) having the same shape is formed. Convex)
Is formed at a position where the starting point forming position α is 130 °. The shape of the second convex portion 5b may be different from the shape of the first convex portion 5.

The convex portion 5 may be formed integrally with the shaft 4 by an appropriate technique such as embossing, pouring, or raising, but in the present embodiment, it is formed at a predetermined position on the shaft 4.
The convex portion 5 is formed by painting, and then the paint is lightly coated on the entire surface of the shaft 4 on which the convex portion 5 is formed (see FIG. 3).
is doing. According to this, since the convex portion 5 can be formed by using the decorative coating material applied to the surface of the shaft 4, the convex portion 5 can be formed easily and inexpensively, and the manufacturing facility can be provided. It can be simplified.

Next, the flow of air around the shaft 4 of the golf club 1 of this embodiment and the shape drag of the shaft 4 will be described. When the golf club 1 is slowly moved, the flow velocity of the flowing air is relatively slow, so that the air flow around the shaft 4 is symmetrical in the front-rear direction and shows a streamline pattern. Therefore, no Karman vortex is generated and the rear side of the shaft 4 is not in a negative pressure state.

On the other hand, when the golf club 1 is swung down at a high speed, the flow velocity of the air flowing relatively increases, and the air flow begins to separate from the rear side of the shaft 4 and reaches the downstream side of the shaft 4. A twin-vortex recirculation zone with backflow is formed. If the flow velocity of air is high,
The vortex can no longer be attached to the shaft stably,
Vortices whose rotation directions are opposite to each other alternately and periodically leave the shaft 4 and flow downstream to form a vortex train. This is the Karman vortex street. Due to this Karman vortex street, a force acts in a direction opposite to the traveling direction of the shaft (indicated by the arrow A in FIGS. 2 and 3), and the shape drag force (pressure resistance) increases.

In the conventional shaft in which the convex portion is not formed, the boundary layer separates in a laminar flow state, but in the shaft 4 of the present embodiment, the convex portion 5 is formed at a predetermined angle position. The convex portion 5 causes the boundary layer to transition from the laminar flow state to the turbulent flow state, and the separation point moves to the downstream side. That is, by delaying peeling to the downstream side, the form drag is reduced.

Further, with the point P, which is the tip on the circumferential surface, as a reference point, a region less than 90 ° from the point P (1 with the point P as the center)
Since the convex portion 5 is not formed in a region within 80 °), the convex portion 5 does not increase the air resistance. This ensures that the overall form drag is reduced.

In particular, in the present embodiment, the optimum condition obtained by experiments for the shaft 4 having an outer diameter of 10 mm, that is, the width L in the circumferential direction is 1.0 mm and the protrusion height H is 0.25 mm. And the starting point forming position θ is 100
Since it is formed so as to be at a temperature of 0 °, the shape drag is greatly reduced compared to the conventional one.

As described above, in the above golf club 1,
Since the geometrical resistance of the shaft 4 can be significantly reduced, the speed of the golf club 1 in downswing or the like can be increased. Further, since the asymmetry of the pressure distribution before and after the shaft 4 is alleviated, it is possible to suppress the generation of cyclic lift, and to stabilize the golf club 1 without being subjected to forced vibration.
Can be swung.

By the way, in the above-mentioned embodiment, the projection 4 is formed on the shaft 4 of the golf club 1, but
For bats, fishing rods, etc. that move in a certain direction at a high speed in the air, or for cylindrical members such as antenna shafts, electric wires, utility poles, etc. where high-speed wind may flow in a certain direction around the circumferential surface. Alternatively, the convex portion may be formed. By forming a convex portion on the antenna shaft, electric wire, electric pole, or the like, it is possible to suppress the generation of negative pressure as much as possible, and thus the durability against strong wind or the like is improved. Also,
Although air is shown as the fluid, it may be liquid. That is, the convex portion may be formed on the one that moves at a high speed in water, or on the columnar member on which the liquid having a high flow velocity may flow in a fixed direction around the circumferential surface.

In the above embodiment, the belt-shaped convex portion 5 is formed continuously in the longitudinal direction of the shaft 4, but it may be partially formed in the longitudinal direction, or intermittently. You may make it form several convex parts. In addition,
When the golf club 1 is swung, the speed is faster toward the tip side of the shaft 4 (the head 3 side). Therefore, when partially forming the convex portion, it is desirable to form the convex portion on the tip side of the shaft 4. Moreover, the cross-sectional shape of the convex portion is not particularly limited, and may be, for example, a circle, an ellipse, or a polygon.

In the above embodiment, the height H of the convex portion 5 and the starting end forming position θ are set to the outer diameter of the substantially central portion of the shaft 4 (about 10
mm) was set to a constant value.
The height H of the convex portion 5 and the starting end forming position θ may be changed according to the change of the outer diameter of the shaft 4. That is, shaft 4
Since the outer diameter of the convex portion is tapered toward the tip side (head 3 side), the upper surface of the convex portion is slightly inclined so that the height H of the convex portion 5 gradually decreases toward the tip side. You may do it.

In the above embodiment, the starting point forming position θ of the convex portion 5 that determines the protrusion amount R and the height H of the convex portion 5, the width L of the convex portion 5, or the number of the convex portions 5 is experimentally determined. Although the optimum condition obtained is shown, it is not always necessary to set the optimum condition, and it can be appropriately changed as long as the drag coefficient can be surely reduced. For example, in FIG.
As shown in FIG. 5, the convex portions 5 may be formed one by one at the left and right rear positions.

[0035]

As described above, the columnar member with a drag reducing function of the invention of claim 1 moves the fluid separation point to the downstream side by the convex portions formed at the left and right rear positions of the columnar member,
The asymmetry of the pressure distribution before and after the cylindrical member can be alleviated. Moreover, since the convex portion is not formed in the region of 90 ° or less from the reference point, which is the tip of the circumferential surface, the convex portion does not significantly increase the air resistance. Therefore, the overall form drag can be reduced,
For example, in a golf club shaft or the like that moves in a fluid at a high speed, the speed can be reliably increased and the golf club can be moved in a stable state.

In addition to the effect of the column member with the drag reducing function of the first aspect, the column member with the drag reducing function of the invention of claim 2 has the protrusion height of the convex portion with respect to the diameter of the column member and the formation position of the convex portion. Is set based on a predetermined relationship, the shape drag can be reliably reduced regardless of the size of the columnar member.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a golf club according to an embodiment of the present invention.

FIG. 2 is a perspective view of an essential part of a golf club according to an embodiment of the present invention, in which a shaft is cut.

FIG. 3 is a cross-sectional view showing a cross section of a shaft of a golf club according to an embodiment of the present invention.

FIG. 4 is experimental data showing a relationship between a convex portion and a drag coefficient on the shaft of the golf club according to the embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a forming position of a convex portion and a drag coefficient on a shaft of a golf club according to an embodiment of the present invention.

FIG. 6 is experimental data and a graph showing a relationship between a width of a convex portion and a drag coefficient in a shaft of a golf club according to an embodiment of the present invention.

FIG. 7 is experimental data showing a drag coefficient when two convex portions are formed on the shaft of the golf club according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a cross section of a shaft according to another embodiment of the present invention.

[Explanation of symbols]

1 golf club 4 shaft (column member with drag reduction function) 5 convex P reference point θ angle (starting point formation position) L width H height

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-225542 (JP, A) JP-A-2000-314408 (JP, A) Actually opened 58-70266 (JP, U) Actually opened 59-122403 (JP, U) Actual development Sho 59-133803 (JP, U) Japanese Patent Publication 48-26304 (JP, B1) Registered utility model 3020671 (JP, U) Registered utility model 3056694 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) A63B 53/10 A01K 87/00 A63B 59/06 F15D 1/00

Claims (2)

(57) [Claims] 1. A columnar member with a drag reducing function in which a convex portion for reducing shape drag is provided on a circumferential surface, wherein the convex portion is centered on a tip on the circumferential surface facing in the fluid flow direction. , Provided at symmetrical positions on the circumferential surface, and the convex portion on the circumferential surface with the tip as a reference (0 °).
To form the starting point of the convex portion
A columnar member with a drag reduction function, which is limited to a range of more than 125 ° or less . 2. The diameter is 10 when the tip is 0 °.
When the protrusion height of the convex portion is 0.0125 times the diameter of the columnar member with respect to the columnar member of mm, the starting end is formed.
If the position is in the range of 91 ° to 93 °, and 0.0175 times, the start end forming position is in the range of 91 ° to 96 °, 0.0
In the case of 25 times, the starting end forming position is within the range of 96 ° to 103 °, and in the case of 0.05 times, the starting end forming position is 102
It is said that the higher the protruding height of the convex portion with respect to the diameter of the cylindrical member is, the larger the difference in angle between the tip end and the start end forming position on the circumferential surface is set so as to fall within the range of ° to 117 °. The columnar member with a drag reducing function according to claim 1, wherein the protruding height of the convex portion and the starting end forming position are determined based on the relationship.