JP5953632B2 - Cutting insert and gear cutting tool - Google Patents

Description

  The present invention relates to a cutting insert and a gear cutting tool.

  Patent Document 1 describes a cutting insert used for gear cutting of an involute gear. This cutting insert includes a flat insert body, and has cutting edges on two sides thereof. Non-Patent Document 1 describes a cutting insert used for gear cutting of an involute gear. This cutting insert has a flat insert body and has cutting edges on its four sides.

International Publication No. 2010/073681 Pamphlet

“KENNAMETAL GEAR PRODUCTION TOOLS” (USA), Kennametal Inc., 2010, p. 9

  As a tool for cutting the teeth of the involute gear, there is known an edge-changeable tool that is used with a cutting insert (also called a throw-away tip) having an involute curved cutting edge. The cutting insert used in such a blade edge replaceable tool typically has a substantially rectangular flat plate shape, one side of which is used as a cutting blade, and two surfaces adjacent to the one side are a flank and a flank. Used as a rake face.

  In such an edge-changeable tool, it is desired that one cutting insert can be used as many times as possible in order to save resources and reduce costs. For example, the cutting insert described in Patent Document 1 described above has two opposing edges on the upper surface of the substantially rectangular flat plate-shaped insert body, and even after one of the cutting edges is worn and cannot be used. The other cutting blade can be replaced and used continuously.

  FIG. 8 is a perspective view showing an example of the shape of a cutting insert having two cutting edges. As shown in FIG. 8, the cutting insert 100 includes a flat insert body 110. The upper surface of the insert main body 110 is a flank 112, and each of the pair of side faces is a rake face 114, 116. One cutting edge 122 is provided at the intersection ridge line portion between one rake face 114 and the flank face 112, and another one is provided at the intersection ridge line portion between the other rake face 116 and the flank face 112. A cutting blade 124 is provided. The shapes of these cutting edges 122 and 124 form an involute curve in a side view of the insert main body 110. The bottom surface 118 of the insert body 110 is formed flat, and this bottom surface 118 abuts against the mounting surface of the tool body. A through hole 130 is formed in the center of the insert body 110 to be screwed to the mounting surface.

  However, in such a cutting insert, only two of the sides of the substantially rectangular flat plate-shaped insert body are used, so a cutting insert that can use more sides as a cutting blade is desired. In that respect, the cutting insert described in Non-Patent Document 1 described above has cutting edges on the four sides of the substantially rectangular flat plate-shaped insert body, and by using these cutting blades in order, the cutting insert can be performed more times. Can continue to use. However, in the cutting insert described in Non-Patent Document 1, since the shape of the cutting blade gradually changes when the cutting blade is re-polished, the life of each of the four cutting blades can be extended by re-polishing. There is a problem that you can not.

  The present invention has been made in view of such problems, and a cutting insert and a tooth that can use four sides of a flat-plate-like insert body as cutting blades and can re-grind these cutting blades. An object is to provide a cutting tool.

  In order to solve the above-described problems, a cutting insert according to the present invention is a cutting insert that is detachably attached to a main body of a gear cutting tool used for gear cutting of an involute gear, and includes an upper surface, a lower surface, and A flat insert body having a pair of side surfaces, the insert body having a first cutting edge provided on a ridge line where one side surface and the upper surface intersect, and one side surface and the lower surface intersect. The second cutting edge provided on the ridge line, the third cutting edge provided on the ridge line where the other side surface and the upper surface of the pair of side surfaces intersect, and the ridge line where the other side surface and the lower surface intersect. A fourth cutting edge provided, a first flank face provided on the upper surface adjacent to the first cutting edge, a second flank face provided on the lower face adjacent to the second cutting edge, Third relief provided on the upper surface adjacent to the third cutting edge And a fourth flank face provided on the lower surface adjacent to the fourth cutting edge, a first rake face provided on one side face adjacent to the first cutting edge, and a second cutting edge. A second rake face provided on one side surface adjacent to the blade, a third rake face provided on the other side surface adjacent to the third cutting edge, and a fourth cutting edge. An involute having a fourth rake face provided on the other side surface, and the shape of the first to fourth cutting blades seen from the normal direction of the pair of side faces bulges outward from the insert body The cross-sectional shape along the pair of side surfaces of the first to fourth flank surfaces is the same as the shape of the first to fourth cutting blades, and the insert body has a first shape on the upper surface. A first flat surface that forms the bottom surface of a recess formed between the flank and the third flank, and a second flank and a fourth flank on the bottom surface It forms a bottom surface of the recess formed between, and further comprising a second flat surface parallel to the first flat surface.

  This cutting insert has four cutting edges provided on four sides of a flat insert body. Since the first flat surface is formed on the upper surface and the second flat surface is formed on the lower surface, one of these flat surfaces is brought into contact with the mounting surface of the main body of the gear cutting tool. By adjusting the orientation of the main body, these four cutting blades can be selectively used. Therefore, according to said cutting insert, compared with the cutting insert described in patent document 1, the frequency | count of use of one cutting insert can be increased markedly.

  Moreover, in said cutting insert, the cross-sectional shape of the 1st-4th flank along the pair of side surface of the insert main body is the same as the shape of the 1st-4th cutting blade. Thereby, even when the 1st-4th cutting blade is re-polished from each side surface, the shape of a cutting blade does not change and a fixed involute curve shape can be maintained. Therefore, according to the cutting insert described above, the four cutting edges can be re-polished, so that the life of each of the four cutting edges can be extended by the re-polishing.

  As described above, according to the cutting insert according to the present invention, the four sides of the flat insert body can be used as cutting edges, and re-polishing of these cutting edges can be enabled.

  The cutting insert has one side surface that is flat from the first rake face to the second rake face, and the other side face that is flat from the third rake face to the fourth rake face. It may be a feature. Thereby, the first to fourth cutting edges can be easily re-polished.

  Further, the cutting insert may be characterized in that a recess is formed in each of the upper surface and the lower surface with the extending direction of the first to fourth cutting edges as the longitudinal direction. Thereby, since the bottom face (namely, the 1st and 2nd flat surfaces) of a crevice can be formed widely, these cutting surfaces are made to contact the main part of a gear cutting tool, and a cutting insert is attached to the main part. It is possible to improve the mounting stability at the time, and it is possible to hold the tool effectively against the load during cutting.

  The cutting insert may be characterized in that when the cutting insert is attached to the main body of the gear cutting tool, the inner wall surface of the concave portion on the upper surface or the lower surface that contacts the main body does not contact the main body. Further, the cutting insert may be characterized in that the inner wall surface of the recess is inclined with respect to the normal line of the first and second flat surfaces on each of the upper surface and the lower surface. The boundary part with the bottom face (the 1st and 2nd flat surfaces) may be connected by the curved surface (R surface).

  In the cutting insert, the insert body further includes a screw insertion hole that penetrates the first flat surface and the second flat surface, and the central axis direction of the screw insertion hole is the first and second flat surfaces. The surface may be perpendicular to the surface or inclined with respect to the normal direction of the first and second flat surfaces.

  A gear cutting tool according to the present invention is a gear cutting tool used for gear cutting of an involute gear, and is a substantially disc-shaped tool body that rotates around an axis, and any one of the plurality of cutting inserts described above. The tool body has a plurality of insert mounting surfaces formed side by side in the circumferential direction on the outer peripheral portion of the tool body, and the plurality of cutting inserts are either the first flat surface or the second flat surface. It is characterized in that it is detachably attached to the tool body so that the insert attachment surfaces are in contact with each other. According to this gear cutting tool, by providing any of the cutting inserts described above, the four sides of the plate-like insert body can be used as cutting blades, and the cutting blades can be polished.

  According to the cutting insert and the gear cutting tool according to the present invention, the four sides of the flat insert body can be used as the cutting blades, and the cutting blades can be polished.

FIG. 1 is a partial side view of the gear cutting tool, and shows the appearance of the gear cutting tool as viewed from the direction of the axis that is the rotation center of the gear cutting tool. FIG. 2 is a partial top view of the gear cutting tool and shows the appearance of the gear cutting tool as viewed from a direction perpendicular to the axis of the gear cutting tool. FIG. 3 is a partial cross-sectional view of the gear cutting tool when cut along a cross-section including an axis. FIG. 4 is a perspective view showing the appearance of the cutting insert in the present embodiment. FIG. 5 is a plan view of the cutting insert, 6A is a side view of the cutting insert, FIG. 6B is a cross-sectional view of the cutting insert along the line VIb-VIb shown in FIG. 5, and FIG. FIG. 6 is a cross-sectional view of the cutting insert along the line VIc-VIc shown in FIG. FIG. 7 is an enlarged perspective view showing the vicinity of a chip pocket and an insert mounting surface formed in the tool body. FIG. 8 is a perspective view showing the shape of a cutting insert as a comparative example. FIG. 9 is a perspective view showing another example of the cutting insert. FIG. 10 is an enlarged perspective view showing another example of the chip pocket and the insert mounting surface formed in the tool body.

  Hereinafter, embodiments of a cutting insert and a gear cutting tool according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  1-3 is a figure which shows the structure of the gear cutting tool 10 which concerns on one Embodiment of this invention. FIG. 1 is a partial side view of the gear cutting tool 10 and shows the appearance of the gear cutting tool 10 as viewed from the direction of the axis A1 that is the rotation center of the gear cutting tool 10. FIG. 2 is a partial top view of the gear cutting tool 10 and shows an appearance of the gear cutting tool 10 viewed from a direction perpendicular to the axis A1 of the gear cutting tool 10. FIG. FIG. 3 is a partial cross-sectional view of the gear cutting tool 10 when cut along a cross-section including the axis A1.

  The gear cutting tool 10 of this embodiment is used for gear cutting of an involute gear. As shown in FIGS. 1 to 3, the gear cutting tool 10 includes a substantially disk-shaped tool body 12, a plurality of cutting inserts 20 attached to the tool body 12, and a plurality of tools attached to the tool body 12. The cutting insert 30 is provided. The tool body 12 is a member that is supported in a machine tool so as to be rotatable about an axis A1 that coincides with the center axis of the disk shape. The tool body 12 has a pair of front and back panel surfaces 12a and 12b having a substantially circular shape when viewed from the direction of the axis A1.

  The tool body 12 is made of, for example, steel, and includes a plurality of chip pockets 14, a plurality of chip pockets 15, a plurality of insert mounting surfaces 16, a plurality of insert mounting surfaces 17, and through holes 18. Have.

  Chip pockets 14 and 15 are pockets for facilitating the generation, storage and discharge of chips during cutting. The shape of the chip pocket 14 and the shape of the chip pocket 15 are different from each other. These chip pockets 14 and 15 are formed side by side in an arbitrary arrangement in the circumferential direction on the outer peripheral portion of the tool body 12. In one example, as shown in FIG. 2, a plurality of chip pockets 14 are formed side by side in the circumferential direction, and two chip pockets per gap are provided in each gap of the chip pockets 14. 15 are formed side by side in the circumferential direction. The plurality of chip pockets 14 are alternately formed on one board surface 12a and the other board surface 12b of the tool body 12, and similarly, the plurality of chip pockets 15 are formed on one board surface 12a and the other board surface 12b. It is alternately formed on the board surface 12b.

  The plurality of insert mounting surfaces 16 are formed by piercing the inner wall of each of the plurality of chip pockets 14 so as to face the rotation direction of the tool body 12 (arrow A2 in FIG. 1), and slightly with respect to the rotation direction A2. It is inclined to. Similarly, the plurality of insert mounting surfaces 17 are formed by piercing a wall surface facing the rotation direction A2 of the tool body 12 among the inner surfaces of the plurality of chip pockets 15, and are slightly inclined with respect to the rotation direction A2. ing. The insert mounting surface 16 and the insert mounting surface 17 have different sizes and aspect ratios. A cutting insert 20 is mounted on the insert mounting surface 16, and the cutting insert 20 is sized on the insert mounting surface 17. Cutting inserts 30 having different aspect ratios are attached.

  The through hole 18 is a hole for attaching the tool body 12 to the rotating shaft of the machine tool. As shown in FIG. 3, the through hole 18 is formed so as to penetrate the central portion of the tool body 12 in the direction of the axis A <b> 1.

  Each of the plurality of cutting inserts 20 is detachably attached to each of the plurality of insert attachment surfaces 16. Similarly, each of the plurality of cutting inserts 30 is detachably attached to each of the plurality of insert attachment surfaces 17. In one example, as shown in FIGS. 1 and 2, the cutting inserts 20 and 30 are screwed to the insert mounting surfaces 16 and 17 by mounting screws 41.

  In FIG. 3, when the tool body 12 is rotated, two cutting areas, a passage area B1 of the cutting insert 20 attached to one board surface 12a, a passage area B2 of the cutting insert 20 attached to the other board surface 12b, and two cuttings. The passing regions B3 and B4 of the inserts 30 and 30 are indicated by phantom lines. As shown in FIG. 3, the cutting insert 20 is attached to be inclined with respect to a plane perpendicular to the axis A1. Then, the cutting blade of the cutting insert 20 attached to one board surface 12a, the cutting blade of the cutting insert 20 attached to the other board surface 12b, and the cutting blades of the two cutting inserts 30 and 30 are used for gear cutting. A series of continuous cutting edges are formed as the tool rotates. When cutting the gear tooth gap, the involute curve drawn by the series of cutting blades is transferred to the workpiece, and the involute tooth profile is cut out.

  FIG. 4 is a perspective view showing an appearance of the cutting insert 20 in the present embodiment. 5 is a plan view of the cutting insert 20, FIG. 6 (a) is a side view of the cutting insert 20, and FIG. 6 (b) is along the VIb-VIb line shown in FIG. FIG. 6C is a cross-sectional view of the cutting insert 20, and FIG. 6C is a cross-sectional view of the cutting insert 20 along the VIc-VIc line shown in FIG.

  As shown in FIGS. 4 to 6, the cutting insert 20 includes a flat insert body 21. The insert body 21 is made of, for example, high speed steel, cemented carbide, cermet, ceramic, ultra high pressure sintered body, or the like. The insert body 21 has an upper surface 21a, a lower surface 21b, a pair of side surfaces 21c and 21d, and a pair of end surfaces 21e and 21f. A predetermined direction (arrow A3 in the figure) is a longitudinal direction when viewed from the thickness direction. It has a rectangular shape. As shown in FIG. 5, the pair of side surfaces 21c and 21d are parallel to each other and extend along a plane formed by a direction intersecting the upper surface 21a and the lower surface 21b and a predetermined direction A3. The pair of end surfaces 21e and 21f are parallel to each other and extend along a plane formed by a direction intersecting the upper surface 21a and the lower surface 21b and a direction intersecting the predetermined direction A3.

  Further, the insert main body 21 has four cutting edges such as a first cutting edge 22a, a second cutting edge 22b, a third cutting edge 22c, and a fourth cutting edge 22d provided along a predetermined direction A3. have. The 1st cutting edge 22a is provided in the ridgeline where one side surface 21c and upper surface 21a cross | intersect among a pair of side surfaces 21c and 21d. The 2nd cutting edge 22b is provided in the ridgeline where one side surface 21c and the lower surface 21b cross | intersect. The 3rd cutting edge 22c is provided in the ridgeline where the other side surface 21d and upper surface 21a cross | intersect among a pair of side surfaces 21c and 21d. The fourth cutting edge 22d is provided on a ridge line where the other side surface 21d and the lower surface 21b intersect. 6A, the shapes of the cutting blades 22a and 22b form an involute curve that swells outward with respect to the insert body 21 when viewed from the normal direction of the side surface 21c. Similarly, the shapes of the cutting blades 22c and 22d form an involute curve that swells outward with respect to the insert body 21 when viewed from the normal direction of the side surface 21d.

  Further, the insert body 21 has four relief surfaces including a first relief surface 23a, a second relief surface 23b, a third relief surface 23c, and a fourth relief surface 23d that extend along a predetermined direction A3. Has a surface. The first flank 23a is provided on the upper surface 21a adjacent to the first cutting edge 22a, and the second flank 23b is provided on the lower surface 21b adjacent to the second cutting edge 22b. The third flank 23c is provided on the upper surface 21a adjacent to the third cutting edge 22c, and the fourth flank 23d is provided on the lower surface 21b adjacent to the fourth cutting edge 22d. Yes.

  The insert main body 21 has four rakes such as a first rake face 24a, a second rake face 24b, a third rake face 24c, and a fourth rake face 24d extending along a predetermined direction A3. Has a surface. The first rake face 24a is provided on the side face 21c adjacent to the first cutting edge 22a, and the second rake face 24b is provided on the side face 21c adjacent to the second cutting edge 22b. The third rake face 24c is provided on the side face 21d adjacent to the third cutting edge 22c, and the fourth rake face 24d is provided on the side face 21d adjacent to the fourth cutting edge 22d. Yes.

  In the present embodiment, the side face 21c is formed flat from the first rake face 24a to the second rake face 24b, and the side face 21c is substantially the first rake face 24a and the second rake face. It forms a single rake face including the face 24b. Similarly, the side face 21d is formed flat from the third rake face 24c to the fourth rake face 24d, and the side face 21d substantially includes the third rake face 24c and the fourth rake face 24d. Make a single rake face.

  Further, as shown in FIG. 6C, the first flank 23a and the second flank 23b are in a cross section perpendicular to the predetermined direction A3 with respect to the side surface 21c (the rake surfaces 24a and 24b). It is formed so as to form a right angle. Similarly, the third flank 23c and the fourth flank 23d are formed to form a right angle with respect to the side surface 21d (rake surfaces 24c, 24d) in a cross section perpendicular to the predetermined direction A3. Therefore, the shape of the cross section along the side surface 21c of the flank surfaces 23a and 23b is the shape of the cutting edges 22a and 22b viewed from the normal direction of the side surface 21c at any cutting position from the side surface 21c to a predetermined depth. It is the same. Similarly, the shape of the cross section along the side surface 21d of the flank surfaces 23c and 23d is the shape of the cutting edges 22c and 22d viewed from the normal direction of the side surface 21d at any cutting position from the side surface 21d to a predetermined depth. It is the same.

  The insert body 21 further includes a first flat surface 25a provided on the upper surface 21a and a second flat surface 25b provided on the lower surface 21b. These first and second flat surfaces 25a and 25b are surfaces that abut against the insert mounting surface 16 (see FIG. 2) when the cutting insert 20 is mounted on the tool body 12 described above. As shown in FIG. 6B, the first and second flat surfaces 25a and 25b are parallel to each other and perpendicular to the side surfaces 21c and 21d.

  In one example, the flat surfaces 25a and 25b form the bottom surface of the recess. That is, the flat surface 25a forms the bottom surface of the recess 26a formed on the upper surface 21a, and the flat surface 25b forms the bottom surface of the recess 26b formed on the lower surface 21b. The recess 26a is formed between the first flank 23a and the third flank 23c, and the extending direction (predetermined direction A3) of the first cutting edge 22a and the third cutting edge 22c is the longitudinal direction. It is formed as. The recess 26b is formed between the second flank 23b and the fourth flank 23d, and the extending direction (predetermined direction A3) of the second cutting edge 22b and the fourth cutting edge 22d is the longitudinal direction. It is formed as.

  The insert body 21 further has a screw insertion hole 27. The screw insertion hole 27 is a hole into which the attachment screw 41 (see FIGS. 1 and 2) is inserted when the cutting insert 20 is attached to the tool body 12 described above, and includes a flat surface 25a and a flat surface. 25b is penetrated in the thickness direction of the insert main body 21. The planar shape of the screw insertion hole 27 viewed from the normal direction of the flat surface 25a is preferably a circle. The direction of the central axis of the screw insertion hole 27 (axis A4 shown in FIGS. 6B and 6C) is preferably perpendicular to the flat surfaces 25a and 25b, but if necessary. In addition, the flat surfaces 25a and 25b may be inclined with respect to the normal direction.

  FIG. 7 is an enlarged perspective view showing the vicinity of the chip pocket 14 and the insert mounting surface 16 formed in the tool body 12. As shown in FIG. 7, the chip pocket 14 extends along the radial direction of the tool body 12, and is formed in a concave shape through the board surface 12 a (or the board surface 12 b). The insert mounting surface 16 is formed by piercing a wall surface facing the rotation direction A2 of the tool body 12 among the inner wall surfaces of the chip pocket 14, and extends with the extending direction of the chip pocket 14 as a longitudinal direction. Note that the longitudinal direction of the insert mounting surface 16 coincides with the longitudinal direction of the cutting insert 20 described above (the predetermined direction A3 shown in FIG. 4). Therefore, the cutting edges 22a to 22d of the cutting insert 20 are arranged along the radial direction of the tool body 12 (crossing the rotation direction A2).

  A screw hole 42 that is screwed into the mounting screw 41 is formed in the insert mounting surface 16. Further, the insert mounting surface 16 includes a cutting edge of the cutting insert 20 attached to one of the board surfaces 12a, a cutting edge of the cutting insert 20 attached to the other board surface 12b, and a cutting edge of the two cutting inserts 30 and 30. The blade is inclined in the radial direction with respect to a plane perpendicular to the axis A1 (see FIGS. 1 and 3) so as to form the tooth profile shown in FIG. The insert mounting surface 16 is a surface adjacent to both sides in the short direction so that the flat surfaces 25a and 25b, which are the bottom surfaces of the recesses 26a and 26b of the cutting insert 20, and the insert mounting surface 16 can contact each other. Is slightly convex.

  However, in the present embodiment, the width in the short direction of the insert mounting surface 16 is sufficiently shorter than the width of the recesses 26a and 26b of the cutting insert 20, and the convex shape of the insert mounting surface 16 is the cutting insert 20. It does not contribute to positioning. That is, when the cutting insert 20 is attached to the tool body 12, the side walls (inner wall surfaces) 28 a and 28 b of the recesses 26 a and 26 b shown in FIG. 6C do not contact the tool body 12. Therefore, the side walls 28a and 28b may be inclined with respect to the normal line of the flat surfaces 25a and 25b, as shown in FIG. 6C, for example. Moreover, the boundary part of side wall 28a, 28b of recessed part 26a, 26b and the bottom face (flat surface 25a, 25b) of recessed part 26a, 26b may be connected by the curved surface (R surface).

  Around the insert mounting surface 16, there are provided a wall surface 19a with which the side surface 21c or 21d of the cutting insert 20 abuts and a wall surface 19b with which the end surface 21e or 21f of the cutting insert 20 abuts. These wall surfaces 19 a and 19 b are provided for positioning the cutting insert 20.

  The chip pocket 15 formed in the tool main body 12 has the same characteristics as the chip pocket 14 although the size and aspect ratio are different from the above-described chip pocket 14. The insert mounting surface 17 formed on the tool body 12 is different in size and aspect ratio from the above-described insert mounting surface 16, but the point that the wall surfaces 19 a and 19 b are provided around the insert mounting surface 16 is the insert mounting surface 17. This is the same as 16.

  The cutting inserts 30 and 30 each have a curve for connecting two involute curves transferred to the workpiece by the cutting insert 20 attached to the board surface 12a and the cutting insert 20 attached to the board surface 12b. Transcript. The curves transferred to the workpiece by these four cutting inserts 20, 20, 30, 30 form one involute curve. The cutting insert 30 includes a flat insert body, and the insert body has four cutting edges provided at four corners on one surface side. The shape of the cutting blade viewed from the normal direction of the side surface of the insert body forms an involute curve, and the sectional shape of the flank along the side surface of the insert body is the same as the shape of the cutting blade. Further, both side surfaces of the insert body are formed flat. Furthermore, the insert body further has a screw insertion hole that penetrates the flat surface on the upper surface and the flat surface on the lower surface.

  The effects obtained by the cutting inserts 20 and 30 having the above configuration and the gear cutting tool 10 will be described.

  The cutting insert 20 of the present embodiment has four cutting blades 22 a to 22 d provided on four sides of a flat insert body 21. Since the flat surface 25a is formed on the upper surface 21a and the flat surface 25b is formed on the lower surface 21b, either one of the flat surfaces 25a and 25b is brought into contact with the insert mounting surface 16 of the tool body 12. The four cutting blades 22a to 22d can be selectively used by adjusting the orientation of the insert body 21. Specifically, the cutting edge 22a (or 22b) is adjusted by adjusting the orientation of the insert body 21 so that the side surface 21c faces the rotation direction while the flat surface 25a (or 25b) is brought into contact with the insert mounting surface 16. Can be used. Further, the cutting edge 22c (or 22d) is used by adjusting the orientation of the insert body 21 so that the side surface 21d faces the rotational direction while the flat surface 25a (or 25b) is brought into contact with the insert mounting surface 16. Can do. Therefore, according to the cutting insert 20 of the present embodiment, compared to the cutting insert described in Patent Document 1, the number of times of use of one cutting insert can be significantly increased.

  Moreover, in the cutting insert 20 of this embodiment, the cross-sectional shape of the relief surfaces 23a-23d along a pair of side surface 21c, 21d of the insert main body 21 is the same as the shape of the cutting blades 22a-22d. In other words, the cross-sectional shape in the vicinity of the cutting edges 22a to 22d of the insert body 21 in the direction along the flank surfaces 23a to 23d is constant. Thereby, even when the cutting blades 22a to 22d are repolished from the side surfaces 21c and 21d, the shape of the cutting blades 22a to 22d does not change, and a constant involute curve shape can be maintained. Therefore, according to this cutting insert 20, since the four cutting blades 22a to 22d can be re-polished, the life of each of the four cutting blades 22a to 22d can be extended by the re-polishing.

  As described above, according to the cutting insert 20 of the present embodiment, the four sides of the flat insert body 21 can be suitably used as the cutting blades 22a to 22d, and the cutting blades 22a to 22d can be used. Re-polishing can be enabled.

  Moreover, according to the gear cutting tool 10 of the present embodiment, by providing the cutting insert 20, the four sides of the flat insert body 21 can be used as the cutting blades 22a to 22d, and these cutting blades 22a. Polishing of ~ 22d can be made possible.

  Moreover, it is preferable that one side surface 21c of the insert body 21 is flat from the rake face 24a to the rake face 24b, and the other side face 21d is flat from the rake face 24c to the rake face 24d as in the present embodiment. Thereby, the cutting blades 22a to 22d can be easily re-polished.

  Moreover, it is preferable that the recessed parts 26a and 26b are formed by making the extending | stretching direction of the cutting blades 22a-22d into a longitudinal direction in each of the upper surface 21a and the lower surface 21b of the insert main body 21 like this embodiment. Thereby, since the recessed parts 26a and 26b do not cross the cutting edge, the bottom surfaces (that is, the flat surfaces 25a and 25b) of the recessed parts 26a and 26b can be formed widely. Therefore, it is possible to increase the mounting stability when the cutting insert 20 is mounted on the tool body 12 by bringing these flat surfaces 25a and 25b into contact with the insert mounting surface 16, and against the load during cutting. It is also possible to hold the tool effectively. Further, in this case, since the flat surface can be formed by one polishing, the flat surfaces 25a and 25b can be easily processed.

  The preferred embodiments of the cutting insert and the gear cutting tool according to the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. .

  In this embodiment, one involute curve is transferred to the workpiece by the four cutting inserts 20, 20, 30, and 30, and the involute gear is cut out. However, the present invention is not limited to this. For example, when the cutting insert 50 shown in FIG. 9 is used, an involute gear can be cut out by transferring one involute curve to the workpiece by the two cutting inserts 50 and 50. The cutting insert 50 basically has the same morphological features as the cutting insert 20 (four cutting blades 52a to 52d, relief surfaces 53a to 53d, a flat surface 55a, and a screw insertion hole 57. Has the same configuration as the cutting blades 22a to 22d, the flank surfaces 23a to 23d, the flat surface 25a, and the screw insertion hole 27 of the above embodiment), and both ends of the pair of side surfaces 51c and 51d are the insert 20 for cutting. Is different from the cutting insert 20 in that the point is sharp. The cutting inserts 30, 30 can be omitted by cutting the portions corresponding to the cutting inserts 30, 30.

  Moreover, in FIG. 7, although the insert mounting surface 16 is formed as a convex top surface which protrudes from the wall surface of the chip pocket 14 formed in the tool main body 12, the insert mounting surface of this invention is in such a form. It is not limited. For example, as shown in FIG. 10, the wall surface of the chip pocket 14 is formed flat, and the plate 58 is provided as another member corresponding to the “convex portion protruding from the wall surface of the chip pocket 14” in FIG. 7. It may be provided. In the case where the insert mounting surface is configured in this way, it is possible to reduce the processing cost as compared with the case where the convex portion is formed on the wall surface of the chip pocket 14 by cutting.

DESCRIPTION OF SYMBOLS 10 ... Tool for gear cutting, 12 ... Tool main body, 14, 15 ... Chip pocket, 16, 17 ... Insert mounting surface, 18 ... Through-hole, 19a, 19b ... Wall surface, 20, 30, 50 ... Insert for cutting, 21 ... insert body, 21a ... upper surface, 21b ... lower surface, 21c, 21d ... side face, 21e, 21f ... end face, 22a ... first cutting edge, 22b ... second cutting edge, 22c ... third cutting edge, 22d ... 4th cutting edge, 23a ... 1st flank, 23b ... 2nd flank, 23c ... 3rd flank, 23d ... 4th flank, 24a ... 1st rake face, 24b ... 2nd Rake face, 24c ... third rake face, 24d ... fourth rake face, 25a ... first flat face, 25b ... second flat face, 26a, 26b ... concave, 27 ... screw insertion hole, 28a, 28b ... sidewall, 41 ... mounting screw, 42 ... screw hole.

Claims (6)

A cutting insert detachably attached to a main body of a gear cutting tool used for gear cutting of an involute gear,
A flat insert body having an upper surface and a lower surface, and a pair of side surfaces,
The insert body is
A first cutting edge provided on a ridge line intersecting one of the side surfaces and the upper surface, a second cutting edge provided on a ridge line intersecting the one side surface and the lower surface, Of the pair of side surfaces, a third cutting edge provided at a ridge line where the other side surface and the upper surface intersect, and a fourth cutting edge provided at a ridge line where the other side surface and the lower surface intersect. A blade,
A first flank surface provided on the upper surface adjacent to the first cutting blade; a second flank surface provided on the lower surface adjacent to the second cutting blade; and the third cutting blade. A third flank provided on the upper surface adjacent to the fourth flank, and a fourth flank provided on the lower surface adjacent to the fourth cutting edge;
A first rake face provided on the one side surface adjacent to the first cutting edge; a second rake face provided on the one side face adjacent to the second cutting edge; And a third rake face provided on the other side surface adjacent to the third cutting edge and a fourth rake face provided on the other side surface adjacent to the fourth cutting edge. And
The shape of the first to fourth cutting blades seen from the normal direction of the pair of side surfaces forms an involute curve that swells outward with respect to the insert body,
The cross-sectional shape along the pair of side surfaces of the first to fourth flank surfaces is the same as the shape of the first to fourth cutting edges,
The insert main body has a first flat surface that forms a bottom surface of a recess formed between the first flank and the third flank on the upper surface, and the second flank on the lower surface. forms a bottom surface of the recess formed between the fourth flank and, further have a second flat surface parallel to said first flat surface,
The cutting insert according to claim 1, wherein the recess is formed in each of the upper surface and the lower surface with the extending direction of the first to fourth cutting edges as a longitudinal direction . The one side surface is flat from the first rake face to the second rake face;
The cutting insert according to claim 1, wherein the other side surface is flat from the third rake surface to the fourth rake surface. Wherein the cutting insert is in attached to the body of the gear cutting tool, wherein the upper surface or side wall of the concave portion of the lower surface abuts against the body is not in contact with the body, according to claim 1 or 2 The cutting insert according to 1. The side wall of the concave portion is inclined with respect to the normal line of the first and second flat surfaces in each of the upper surface and the lower surface, according to any one of claims 1 to 3. Cutting insert as described. The insert body further includes a screw insertion hole penetrating the first flat surface and the second flat surface;
A central axis direction of the screw insertion hole is perpendicular to the first and second flat surfaces, or is inclined with respect to a normal direction of the first and second flat surfaces. The cutting insert according to any one of claims 1 to 4 . A gear cutting tool used for gear cutting of involute gears,
A substantially disk-shaped tool body that rotates about an axis;
A plurality of cutting inserts according to any one of claims 1 to 5 ,
The tool body has a plurality of insert mounting surfaces formed side by side in the circumferential direction on the outer periphery of the tool body,
The plurality of cutting inserts are detachably attached to the tool body so that one of the first and second flat surfaces and the insert mounting surface are in contact with each other. tool.

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