JPH0647614A - Throw away chip - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to secure the strength of the tool body and the cutting edge while preserving the advantage that a large axial rake angle can be obtained in the throw-away turning tool. [Structure] A chip body 3 having a substantially parallelogram shape in plan view
One of the cutting edge ridges 38 and 40 formed on the intersecting line of the upper surface 32 of 0 and two adjacent side surfaces 34 and 36 of the chip body 32 is the bottom blade, and the other is the outer peripheral blade. In the throw-away tip attached to the tool body 1 as described above, the upper surface 3 of the tip body 30
2 has a concave curved surface, and the concave curved surface has a cutting edge ridge 38 of the outer peripheral blade.
And a cylindrical surface having a central axis inclined in a plan view with respect to the diagonal line of the parallelogram. [Effect] The rake angle and the cutting edge angle can be made larger than in the case where the concave curved surface is not formed. Therefore, at the base end portion of the tool body, the rake angle and the cutting edge angle of the tip can be made relatively large. Therefore, it is possible to maintain good sharpness at the base end portion having a large cut and secure the edge strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away tip mounted on a throw-away type cutting tool such as an end mill.

[0002]

2. Description of the Related Art As a conventional example of a throw-away tool equipped with such a throw-away tip (hereinafter referred to as a tip), a milling cutter (specifically, an end mill) disclosed in Japanese Patent Application Laid-Open No. 1-281810. ). This throw-away tool is shown in FIGS.
Will be described.

Reference numeral 1 is a main body. The main body 1 is composed of a conical portion 2 and a tip portion 3. The tip portion 3 is provided with recesses 4 and 5 (5 is not shown), which are displaced from each other by 180 °. Inserts for cutting (throw-away tips) are provided in these recesses 4 and 5, respectively.
6 and 7 are attached by bolts 8, respectively. Reference numerals 4'and 5'indicate housings formed in the recesses 4 and 5 to support the throw-away tips 6 and 7, respectively.

The throw-away tip 6 attached to the main body 1 has a shape as shown in FIG. 10
Is a main cutting edge, 11, 11 'and 11''are sub cutting edges, and 12 is a tip portion. The upper surface of the throw-away tip 6 has a concave curved shape in a cross section orthogonal to the main cutting edge 10 as shown in the drawing (thus, forming a part of a cylindrical surface having a central axis parallel to the ridge of the main cutting edge 10). , The blade angle is χ. The clearance angle is α.

In the tool having the above construction, since the upper surface of the throw-away tip is concave, the rake angle in the radial direction can be increased as compared with the case where the upper and lower surfaces are parallel, and the housing is also Since 4 ′ is inclined at an angle of γa, the rake angle in the axial direction can be increased as compared with the case where the housing 4 ′ is horizontal (parallel to the axis of the tool body).

[0006]

By the way, in such a throw-away type tool, since the rake angle in the axial direction is secured by the inclination of the housing 4 ',
It is unavoidable that the wall thickness h of the tool body on the back side of the throw-away tip on the base end side of the housing 4 ′ becomes small.
Further, in order to secure the wall thickness h, the rake angle in the axial direction must be sacrificed or the clearance angle of the throw-away tip must be reduced. Therefore, there is a problem that it is difficult to apply it to a small-diameter tool having a small absolute value of wall thickness, or a problem that the cutting edge strength of the throw-away tip is insufficient.

In the mounting structure in which the base end side of the housing is lowered as described above, the positional relationship between the center of rotation of the tool body and the cutting edge is different between the tip end side and the base end side of the tool body,
The depth of cut on the base end side of the tool body is large. On the other hand, the center axis of the throw-away tip itself is the main cutting edge 10.
Since it is a concave curved surface that forms a part of the cylindrical surface parallel to
Since the cutting edge angle is constant at any position from the tip side to the base end side of the main cutting edge 10, there is a problem that the strength of the cutting edge becomes insufficient on the base end side with a large cut.

The present invention has been made in view of the above circumstances, and retains the advantage that a large axial rake angle can be obtained in the conventional cutting tool using the throw-away insert, while maintaining the advantage of the tool body and The purpose is to ensure the strength of the cutting edge.

[0009]

In order to achieve the above object, the invention of claim 1 has an upper surface of a chip body having a substantially parallelogram shape in plan view and two side surfaces of the chip body which are adjacent to each other. In the throw-away tip attached to the tool body so that one of the cutting edge ridges formed on the line intersecting with the bottom edge and the other edge becomes the outer edge, the upper surface of the tip body has a concave curved surface, The curved surface is not parallel in plan view to any of the cutting edge ridges that become the outer peripheral blades and the diagonal lines of the parallelogram, and approaches the cutting edge ridges of the outer peripheral blades as it moves away from the bottom blade. It is configured to form a part of a cylindrical surface having a central axis line oriented in the direction. According to a second aspect of the present invention, in the first aspect, the central axis of the cylindrical surface is inclined at 5 ° to 30 ° with respect to the cutting edge line of the outer peripheral blade.

[0010]

According to the above construction, the rake face of the chip upper surface is formed by one smoothly continuous curved surface. Further, since the axis of the cylindrical surface is closer to the cutting edge ridge on the base end side than on the tip end side of the tool body, the rake angle and the cutting edge angle of the tip can be increased. In addition, by keeping the inclination angle of the axis of the cylindrical surface within the above range, the rake angle at the base end is maintained at the minimum value that can obtain a practically good cutting surface, and the normal cutting speed The edge strength required for processing can be obtained.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, the same parts as those in the conventional example are designated by the same reference numerals to simplify the description. 1 to 3 show an end mill to which the present invention is applied. A tip pocket 20 is formed at the tip of this tool, and chip receiving surfaces 22 and 24 for receiving the side surfaces of the throw-away tip 30 are formed in the tip pocket 20 as well as the bottom surface of the throw-away tip 30. Chip receiving surface 2
6 is formed. Also in this embodiment, similarly to the conventional milling cutter, the tip receiving surface 26, which is the housing of the throw-away tip, is inclined by ε ° with respect to the axis of the main body 1 to ensure the axial rake angle. There is.

Next, the structure of the throw-away tip 30 used by being attached to the above tool will be described. As shown in FIGS. 4 to 7, in the chip 30 of this embodiment, the upper surface 32 serving as the rake face of the chip 30 is a parallelogram in plan view (each side of the parallelogram diameter) as shown in FIG. Is a positive-type chip. Intersection ridge lines 38, 40 formed by the upper surface 32 and a pair of side surfaces 34, 36 adjacent to each other with a pair of acute-angled portions located on one diagonal of the parallelogram, that is, the acute-angled portion of the parallelogram. The two sides to be sandwiched are used as a cutting edge on the outer peripheral side and a cutting edge on the bottom side, respectively, when the insert 30 is attached to the throw-away type tool as described above. Reference numeral 42 is a bottom surface parallel to the top surface 32.

The upper surface 32 has a concave shape as shown in FIGS. This concave curved surface forms a part of a cylindrical surface centered on an axis C having an angle of θ with respect to the straight line c2 as shown in FIG. 4, and its radius is set to R. Further, the upper surface 32 of the tip 30 is inclined at an inclination angle of γ ° with respect to the seating surface (bottom surface) 42 as shown in FIG. Therefore, when this chip is attached to the tool body, the rake angle C ° of the tool as a whole is the angle ε of the seating surface.
And the tilt angle γ ° of the tip 30. Note that reference numeral 4
Reference numeral 4 denotes a concave curved valley line on the upper surface of the tip 30 (which coincides with the axis C of the cylindrical surface in plan view), and reference numeral 46 denotes a clamp hole into which the bolt 8 for mounting the tip on the tool body is inserted.

The radial rake angle of the cutting edge 38 on the outer peripheral side in the throw-away tip 30 having the above-described structure is inclined so that the axis of the cylindrical surface gradually approaches the cutting edge ridge 38 from the distal end side to the proximal end side. As shown in FIG. 7,
The angle is α ° on the tip end side of the tool, and gradually decreases toward the base end side to β °. Note that in FIG. 7, for convenience, the cutting edge on the seating surface side shows the rake angle β ° on the base end side.

The change in the radial rake angle will be described in more detail with reference to FIGS. 8 and 9. FIG. 8 shows the tip side of the cutting blade, and FIG. 9 shows the base end side of the cutting blade. In these figures, the rake angle on the tip side is A ₁ ° and the cutting edge angle is B ₁ °
And the rake angle at the base end side is A ₂ ° and the cutting edge angle is B ₂ °
Then, A ₁ <A ₂ and B ₁ <B ₂ are established, and both the rake angle and the cutting edge angle gradually increase toward the base end side. Therefore, even though the depth of cut gradually increases toward the base end side, the cutting edge angle can be increased to maintain the strength and the rake angle can be increased to improve the sharpness.

The preferred range of α ° is 10 ° to 2
If the angle is 5 ° and is less than the lower limit, the sharpness becomes poor, and if it exceeds the upper limit, the cutting edge strength is insufficient.

The preferred range of β ° is 5 ° to 1
If it is 5 ° and is less than the lower limit, sharpness becomes poor, and if it exceeds the upper limit, the cutting edge strength becomes insufficient.

The preferred range of θ ° is 5 ° to 30.
If the angle is less than the lower limit and the curved surface is the cutting edge ridge line 38 on the outer periphery,
Too close to the blade, it becomes impossible to obtain a sufficiently large rake angle or cutting edge angle on the base end side compared to the tip of the blade. On the other hand, when the upper limit is exceeded, the rake angle β ° falls below the above range, resulting in poor sharpness, and when the axis of the cylindrical surface increases until it overlaps the diagonal line, the rake angle β
The angle becomes zero, and it becomes impossible to secure the rake angle.

In the above-described embodiment, the cutting edge ridge 38 is configured to be linear in a side view (viewed from the direction of the straight line c1). As a result of the movement, the cutting edge ridge line 38, which serves as the outer peripheral blade, has a radius r as shown in FIGS.
It is also possible to form a convex curve having a middle height at approximately the center of the cutting edge ridgeline 38.

By adopting such a convex curved shape,
It is possible to increase the flatness of the work surface machined by the outer peripheral blade.

Needless to say, the specific structure of the present invention is not limited to the above embodiment.

[0022]

As described above, according to the present invention,
Tool so that one side of the cutting edge ridge line formed on the line where the top surface of the chip body, which has a substantially parallelogram shape in plan view, intersects with each of the two adjacent side surfaces is the bottom blade, and the other is the outer peripheral blade In the throw-away tip attached to the main body, the upper surface of the tip main body has a concave curved surface, and the concave curved surface has a plan view with respect to both the cutting edge ridge line serving as the outer peripheral blade and the diagonal line of the parallelogram. Is not parallel, and since it is configured to form a part of a cylindrical surface having a central axis directed in a direction approaching the cutting edge ridge of the outer peripheral blade as it moves away from the bottom blade, The rake face is formed by one smoothly continuous curved surface. Also, since the axis of the cylindrical surface is closer to the cutting edge ridge on the base end side than on the tip side of the tool body, this is the case when this throw-away tip is attached to the tool body by the receiving surface inclined with respect to the axis line. However, the rake angle and the cutting edge angle can be made larger than in the case where the concave curved surface is not formed, and therefore, at the base end of the tool body,
The rake angle and the cutting edge angle of the tip can be made relatively large, and therefore, good cutting performance can be maintained and the cutting edge strength can be secured at the base end portion having a large cut. Also, because the rake angle becomes large as described above,
The inclination of the receiving surface of the tool body can be made relatively small, and the wall thickness of the tool body can be secured on the back side of the tip receiving surface to enhance the strength.

According to a second aspect of the present invention, in the first aspect, the central axis of the cylindrical surface is inclined at 5 ° to 30 ° with respect to the cutting edge ridge of the outer peripheral blade,
By setting the inclination angle in the above range, the rake angle at the base end portion can be maintained at the minimum value at which a practically good cutting surface can be obtained, and an appropriate cutting edge strength can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which a throw-away tip according to an embodiment of the present invention is attached to a tool.

2 is a side view of the tool of FIG. 1. FIG.

FIG. 3 is a front view of the tool of FIG. 1 seen from the tip direction.

FIG. 4 is a plan view of a throw-away tip according to an embodiment.

5 is a side view seen from the direction of line c1 in FIG. 4. FIG.

6 is a side view seen from the direction of line c2 in FIG. 4.

FIG. 7 is a side view seen from the direction of the line C in FIG.

8 is an enlarged front view of the tool of FIG. 1 when viewed from the tip side.

9 is a cross-sectional view taken along a plane orthogonal to the axis of the base end portion of the tool shown in FIG.

FIG. 10 is a plan view of a throw-away tip according to another embodiment of the present invention.

11 is a side view of the throw-away tip of FIG. 10 as seen from the direction of a chain line c1.

FIG. 12 is a plan view of a rolling tool using a throw-away insert according to a conventional example.

FIG. 13 is a side view of the tool of FIG.

14 is a side view seen from the direction of the cutting edge ridge of the outer peripheral blade of the throw-away tip attached to the tool in FIG.

[Explanation of symbols]

1 Tool body 20 Chip pocket 22, 24
Receiving surface 26 Receiving surface 30 Throw-away tip 32 Receiving surface 34,36 Side surface 38,40
Cross ridge 42 Bottom 44 Valley

Claims (2)

[Claims] 1. One of the cutting edge ridge lines formed on the intersecting line between the upper surface of a chip body having a substantially parallelogram shape in plan view and two adjacent side surfaces of the chip body serves as a bottom blade. In the throw-away tip attached to the tool body such that the other is the outer peripheral blade, the upper surface of the tip body has a concave curved surface, and the concave curved surface has a cutting edge ridge line serving as the outer peripheral blade and the parallelogram. Is not parallel to any of the diagonal lines in a plan view, and forms a part of a cylindrical surface having a central axis oriented toward the cutting edge ridge of the outer peripheral blade as it moves away from the bottom blade. Throw-away tip featuring. 2. The throw-away tip according to claim 1, wherein the central axis of the cylindrical surface is inclined at 5 ° to 30 ° with respect to the cutting edge ridge of the outer peripheral blade. .