Cutting tool

Abstract

This cutting tool comprises a chip breaker 30 having two pocket parts 31 that extend in mutually opposite directions from a cutting edge 21 on a rake face 22 of a blade part 20, and a rib part 32 that is formed flush with the rake face 22 and separates the two pocket parts 31. The cutting tool makes it possible to break and subdivide chips 50 generated through cutting by the cutting edge 21 in each pocket part 31. Furthermore, forming the rib part 32 flush with the rake face 22 helps ensure adequate strength of the cutting edge 21.

Description

cutting tools

[0001] The present invention relates to a cutting tool, and more particularly to a cutting tool with a chip breaker.

[0002] Conventionally, techniques for effectively discharging chips from cutting tools have been known. For example, Patent Document 1 describes a cutting tool having a cutting portion with a cutting edge, a base portion that holds the cutting portion, and a chip guide wall that is formed on the outer peripheral surface of the base portion and that interferes with chips from a workpiece and guides the chips in a direction away from the cutting edge.

[0003] Japanese Patent Application Laid-Open No. 2017-192992

[0004] It is common for cutting tools to clean chips after use, but as the shapes of parts being machined become more complex, chips may remain near the cutting edge even after cleaning. To improve cleanability, it is desirable to break down the chips into smaller pieces. The cutting tool described in Patent Document 1 can discharge chips using a guide wall, but does not consider breaking down the chips themselves into smaller pieces. While providing a chip breaker as a structure for breaking down chips into smaller pieces is conceivable, the strength of the cutting edge may be reduced depending on the chip breaker's structure.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide a cutting tool equipped with a chip breaker that can break down chips into smaller pieces while ensuring good strength of the cutting edge.

[0006] In order to achieve the above object, the cutting tool of the present invention is a cutting tool comprising a cutting portion including a cutting edge for cutting a workpiece, and a chip breaker provided on the cutting portion, wherein the chip breaker has two pocket portions extending in opposite directions from the cutting edge on a rake face of the cutting portion, and a beam portion that separates the two pocket portions and is formed flush with the rake face.

[0007] According to the cutting tool of the present invention, chips cut by the cutting edge can be divided into smaller pieces within each pocket. Furthermore, by forming the beam portion flush with the rake face, the strength of the cutting edge can be secured.

[0008] 5 is a perspective view showing a cutting tool of an embodiment; FIG. 6 is an enlarged view showing the area surrounded by the dashed line in FIG. 1; FIG. 7 is a plan view showing a cutting portion in the vicinity of a chip breaker; FIG. 8 is a perspective view showing a cross section of the cutting portion in the vicinity of the chip breaker taken midway in the tangential direction; FIG. 9 is a perspective view showing a cross section of the cutting portion taken midway in the relative feed direction in FIG. 4; FIG. 10 is a cross section of the cutting portion as seen from the direction of the outline arrow in FIG. 5; FIG. 11 is a cross section taken along line A-A in FIG. 3; FIG. 12 is a plan view showing a cutting portion in the vicinity of a chip breaker of a modified example;

[0009] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a cutting tool according to the embodiment, and FIG. 2 is an enlarged view of the area enclosed by the dashed line in FIG. 1 . As shown in FIG. 1 , the cutting tool 1 is a tool that rotates relative to a workpiece (not shown) and is fed in a relative feed direction X to perform cutting. The workpiece may be, for example, an inner diameter hole included in a cylinder head of an internal combustion engine, but is not limited thereto. The cutting tool 1 is formed, for example, from polycrystalline sintered diamond (PCD), but may also be formed from other materials. As shown in FIG. 1 , the cutting tool 1 includes a main body 10 and a cutting edge 20 provided on the main body 10.

[0010] The main body 10 is a columnar member fixed to the base 12. The axial direction (longitudinal direction) of the main body 10 coincides with the relative feed direction X of the cutting tool 1. A notch 10s is formed on the outer circumferential surface of the main body 10, extending along the relative feed direction X and the circumferential direction. The notch 10s serves as a path for discharging chips 50 (see FIG. 3 ) of the workpiece generated during cutting by the cutting section 20.

[0011] The blade portion 20 is a tip attached to the tip of the main body portion 10 within the notch 10s. In this embodiment, the blade portion 20 is a member with a generally rectangular cross section extending along the relative feed direction X. As shown in FIG. 2 , the blade portion 20 includes a cutting edge 21 that cuts the workpiece. The cutting edge 21 is a corner of the blade portion 20 located downstream in the relative rotation direction α (FIG. 1 shows the relative rotation direction of the cutting tool 1 with respect to the workpiece, not shown). The cutting edge 21 protrudes outward from the outer circumferential surface of the main body portion 10 in the radial direction Y of the main body portion 10 (the width direction perpendicular to the longitudinal direction).

[0012] As shown in FIG. 2 , the blade portion 20 has a rake face 22 located on the advancing direction side (downstream side) of the cutting direction (i.e., the relative rotation direction α). The rake face 22 extends from the cutting edge 21 toward the main body 10 and toward the relative feed direction X. In this embodiment, a step portion 22 a is provided on the rake face 22, and the step portion 22 a can guide the discharge of chips 50. The blade portion 20 also has a first surface 23 and a second surface 24 that intersect with the rake face 22. The first surface 23 and the second surface 24 are surfaces that extend in directions away from each other, sandwiching a ridge line 25 extending from the cutting edge 21. The ridge line 25 is perpendicular to the relative feed direction X and the radial direction Y, and extends along a tangent direction Z of the cutting direction (i.e., the relative rotation direction α) at ​​the cutting edge 21.

[0013] The cutting portion 20 configured as described above further includes a chip breaker 30, which is a structure for breaking up (dividing) chips 50 cut by the cutting edge 21. FIG. 3 is a plan view showing the cutting portion 20 in the vicinity of the chip breaker 30. FIG. 4 is a perspective view showing a cross section of the cutting portion 20 in the vicinity of the chip breaker 30, taken midway in the tangential direction Z. FIG. 5 is a perspective view showing a cross section of the cutting portion 20 taken midway in the relative feed direction X in FIG. 4. FIG. 6 is a cross section of the cutting portion 20 as viewed from the direction of the white arrow in FIG. 5. FIG. 7 is a cross section taken along line A-A in FIG. 3.

[0014] As shown in the figure, the chip breaker 30 has two pockets 31. The two pockets 31 are recesses formed on the rake face 22. As shown in FIG. 3 , the two pockets 31 extend in opposite directions from the cutting edge 21. More specifically, the two pockets 31 include a first pocket 311 extending from the cutting edge 21 along the ridge line 26 between the rake face 22 and the first surface 23, and a second pocket 312 extending from the cutting edge 21 along the ridge line 27 between the rake face 22 and the second surface 24. When chips 50 cut by the cutting edge 21 enter each of these pockets 31, the chips 50 are easily broken into pieces of a size that can fit within each pocket 31. While the edges of each pocket 31 do not necessarily need to coincide with the ridge lines 26 and 27, it is preferable that they be located close to each other. This makes it easier for chips 50 cut by the cutting edge 21 to be captured by each pocket 31.

[0015] 3 to 6, each pocket 31 has a first tapered surface 31a that extends away from the rake face 22 as it moves away from the edge along the ridgelines 26 and 27, a flat surface 31b that extends flatly from the first tapered surface 31a, and a second tapered surface 31c that extends toward the rake face 22 as it moves away from the flat surface 31b. With this configuration, chips 50 cut by the cutting edge 21 are guided by the first tapered surface 31a in a direction away from the cutting edge 21, and furthermore, are easily discharged from each pocket 31 via the second tapered surface 31c.

[0016] The chip breaker 30 has beam portions 32 that separate the pocket portions 31. As shown in Fig. 3, the beam portions 32 extend from the cutting edge 21 to the rake face 22 on a plane including the ridge line 25 (Fig. 2). As shown in Fig. 7, the tops 32a of the beam portions 32 are formed in a position flush with the rake face 22 (shown by the dashed line in Fig. 7). This prevents the strength of the cutting edge 21 from decreasing.

[0017] As described above, the cutting tool 1 of the embodiment includes a chip breaker 30 having two pockets 31 extending in opposite directions from the cutting edge 21 on the rake face 22 of the cutting portion 20, and a beam 32 that separates the two pockets 31 and is formed flush with the rake face 22. As described above, the cutting tool 1 of the embodiment can break up and subdivide chips 50 cut by the cutting edge 21 within each pocket 31. Furthermore, by forming the beam 32 flush with the rake face 22, the strength of the cutting edge 21 can be favorably ensured.

[0018] FIG. 8 is a plan view showing a cutting edge near a chip breaker according to a modified example. In the chip breaker 40 shown in FIG. 8 , each pocket 31 has multiple protrusions 35 protruding from the bottom surface (here, the first tapered surface 31 a). As shown, the multiple protrusions 35 extend straight from the edge of each pocket 31 on the ridge lines 26 and 27 side. Note that in FIG. 2 , the shapes of the multiple protrusions 35 are illustrated by dashed lines. The protrusions 35 are formed, for example, at intervals from one another on the first tapered surface 31 a. This allows chips 50 cut by the cutting edge 21 to move over the multiple protrusions 35 inside each pocket 31 and less likely to come into contact with the bottom surface (the first tapered surface 31 a). As a result, chips 50 are more easily broken.

[0019] Although the description of the embodiment is now complete, aspects of the present invention are not limited to this embodiment. For example, the shape and size of each pocket portion 31 may be adjusted as appropriate, taking into consideration the ease of taking in, discharging, and breaking up the chips 50. The lengths of the pocket portions 31 do not need to be the same, and may be adjusted as appropriate, such as making the first pocket portion 311 longer than the second pocket portion 312. Furthermore, the number, length, protruding height, and formation interval of the multiple protrusions 35 may be adjusted as appropriate, taking into consideration the ease of breaking up the chips 50.

[0020] REFERENCE SIGNS LIST 1 Cutting tool 10 Main body 10s Notch 20 Cutting edge 21 Cutting edge 22 Rake face 30, 40 Chip breaker 31 Pocket 32 ​​Beam 35 Multiple protrusions X Relative feed direction (axial, longitudinal direction) Y Radial direction (width direction) Z Tangential direction

Claims

1. A cutting tool comprising a cutting section including a cutting edge for cutting a workpiece, and a chip breaker provided on the cutting section, wherein the chip breaker has: two pocket sections extending in opposite directions from the cutting edge on the rake face of the cutting section; and a beam section separating the two pocket sections and formed flush with the rake face.

2. The cutting tool according to claim 1, wherein the pocket portion has a plurality of protrusions formed therein that protrude from the bottom surface.

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