cutting tools

Abstract

The cutting tool involved in one embodiment of the present invention is a cutting tool that can rotate around a rotation axis and has a main body. The main body has a front end face, a rear end face and a side face. A spiral first groove and a second groove are formed on the side face of the main body. The second groove is adjacent to the rear side of the main body in the rotation direction when viewed from the first groove. In order to set the cutting blade, the first groove has more than four setting surfaces inside. The first setting surface is located at the position closest to the rear end face among the more than four setting surfaces. The second setting surface is located closer to the front end face than the first setting surface. The length from the first setting surface to the second groove of the main body in the circumferential direction along the rotation direction is set as the first length. The length from the second setting surface to the second groove in the circumferential direction is set as the second length. The first length is longer than the second length.

Description

Technical Field

[0001] The present invention relates to cutting tools. Background Art

[0002] Conventionally, there is known a cutting tool including a rotatable main body and a plurality of cutting inserts arranged on the wall surface of a chip discharge groove formed on the outer periphery of the main body (see, for example, Japanese Patent Application Laid-Open No. 2016-190274).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-190274 Summary of the Invention

[0004] The cutting tool involved in one embodiment of the present invention is a cutting tool that can rotate around a rotation axis and has a main body. The main body has a front end face, a rear end face and a side face. The side face is connected to the front end face. The rear end face is connected to the side face and is located on the opposite side of the front end face along the direction of the rotation axis. A spiral first groove and a second groove are formed on the side face of the main body. The second groove is adjacent to the rear side of the main body in the rotation direction when viewed from the first groove. The first groove has four or more setting surfaces inside. The four or more setting surfaces are used to set the cutting blade. The four or more setting surfaces include the first setting surface and the second setting surface arranged from the third and subsequent positions from the front end face side of the main body. The first setting surface is located at the position closest to the rear end face among the four or more setting surfaces. The second setting surface is located closer to the front end face side than the first setting surface. Each of the four or more setting surfaces has a fixing hole for fixing the cutting blade. On the four or more setting surfaces, the center of each fixing hole is set to the center of each of the four or more setting surfaces. In the first section, which passes through the center of the first installation surface and is perpendicular to the rotation axis, the intersection of a half-line extending from the center of the first installation surface to the rotation axis and outward from the side surface is defined as the first starting point. In the first section, the intersection of the side wall of the second groove on the first groove side and the side surface is defined as the first end point. The length of the side surface of the main body portion from the first starting point to the first end point in the first section is defined as the first length. In the second section, which passes through the center of the second installation surface and is perpendicular to the rotation axis, the intersection of a half-line extending from the center of the second installation surface to the rotation axis and outward from the side surface is defined as the second starting point. In the second section, the intersection of the side wall of the second groove on the first groove side and the side surface is defined as the second end point. The length of the side surface of the main body portion from the second starting point to the second end point in the second section is defined as the second length. In this case, the first length is longer than the second length. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 It is a perspective schematic diagram of the cutting tool according to the first embodiment of the present invention.

[0006] Figure 2 yes Figure 1 A schematic side view of the cutting tool is shown.

[0007] Figure 3 yes Figure 2 Schematic diagram of the cross section at line segment III-III.

[0008] Figure 4 yes Figure 1 A schematic side view of the cutting tool is shown.

[0009] Figure 5 yes Figure 4 Schematic diagram of the cross section at the line segment V-V.

[0010] Figure 6 Viewed from the front side Figure 1 A schematic front view of the cutting tool is shown.

[0011] Figure 7 It is used for Figure 1 A side view schematically illustrating the structure of a cutting tool is shown.

[0012] Figure 8 It is used for Figure 1 A side schematic diagram illustrating the axial rake angle of the cutting tool is shown.

[0013] Figure 9 It is used for Figure 1 A side schematic diagram illustrating the axial rake angle of the cutting tool is shown.

[0014] Figure 10 It is a perspective schematic diagram of a cutting tool according to a second embodiment of the present invention.

[0015] Figure 11 yes Figure 10 A schematic side view of the cutting tool is shown.

[0016] Figure 12 yes Figure 11 Schematic diagram of the cross section at line segment XII-XII.

[0017] Figure 13 yes Figure 10 A schematic side view of the cutting tool is shown.

[0018] Figure 14 yes Figure 13 Schematic diagram of the cross section at line segment XIV-XIV.

[0019] Figure 15 Viewed from the front side Figure 10 A schematic front view of the cutting tool is shown.

[0020] Figure 16 This is a schematic diagram used to illustrate the test method. DETAILED DESCRIPTION

[0021] [Problems to be Solved by the Invention]

[0022] Conventional cutting tools suppress vibrations (so-called chatter vibrations) during cutting by adjusting the arrangement of the cutting inserts. However, there are limits to suppressing chatter vibrations by adjusting the arrangement of the cutting inserts.

[0023] The present invention is made to solve the above-mentioned problems and, more specifically, to provide a cutting tool capable of suppressing chatter vibration during cutting.

[0024] [Effects of the Invention]

[0025] According to the cutting tool according to the present invention, chatter vibration during cutting can be suppressed.

[0026] [Overview of Embodiments]

[0027] First, embodiments of the present invention will be described by way of examples.

[0028] (1) A cutting tool according to one embodiment of the present invention is a cutting tool capable of rotating about a rotation axis and has a main body. The main body has a front end face, a rear end face, and a side face. The side face is connected to the front end face. The rear end face is connected to the side face and is located on the opposite side of the front end face in the direction along the rotation axis. A spiral first groove and a second groove are formed on the side face of the main body. The second groove is adjacent to the rear side of the main body in the rotation direction when viewed from the first groove. The first groove has four or more setting surfaces inside. The four or more setting surfaces are used to set the cutting blade. The four or more setting surfaces include the first setting surface and the second setting surface arranged from the third onward from the front end face side of the main body. The first setting surface is located closest to the rear end face side among the four or more setting surfaces. The second setting surface is located closer to the front end face side than the first setting surface. Each of the four or more setting surfaces has a fixing hole for fixing the cutting blade. On the four or more setting surfaces, the center of each fixing hole is set to the center of each of the four or more setting surfaces. In the first section, which passes through the center of the first installation surface and is perpendicular to the rotation axis, the intersection of a half-line extending from the center of the first installation surface to the rotation axis and outward from the side surface is defined as the first starting point. In the first section, the intersection of the side wall of the second groove on the first groove side and the side surface is defined as the first end point. The length of the side surface of the main body portion from the first starting point to the first end point in the first section is defined as the first length. In the second section, which passes through the center of the second installation surface and is perpendicular to the rotation axis, the intersection of a half-line extending from the center of the second installation surface to the rotation axis and outward from the side surface is defined as the second starting point. In the second section, the intersection of the side wall of the second groove on the first groove side and the side surface is defined as the second end point. The length of the side surface of the main body portion from the second starting point to the second end point in the second section is defined as the second length. In this case, the first length is longer than the second length.

[0029] Here, the closer to the rear end face side of the first groove, the less likely it is for chips to get clogged. That is, there is the bottom surface of the cut material (workpiece) on the front end face side, so the space for the chips generated by the cutting blade to be discharged is relatively small. With respect to the second cutting blade from the front end face side in the first groove, there is a portion in the main body that holds the cutting blade on the front end face side, so the space for discharging the chips is relatively small. Therefore, with respect to the first and second cutting blades from the front end face side mentioned above, chips are easily clogged. On the other hand, with respect to the cutting blades arranged from the third and later from the front end face side in the first groove, even if the capacity of the space for discharging chips is set to the same level as the capacity of the corresponding space associated with the cutting blade on the front end face side mentioned above, sometimes chips will accumulate at the bottom (front end face side) due to gravity. Therefore, the closer to the front end face side of the main body, the more likely it is for chips to get clogged. In addition, the surface (upper surface) of the cut material is located on the rear end face side of the first groove, and sufficient space can be ensured further back than this surface. Therefore, the rear end face side of the first groove is relatively difficult to be clogged with chips compared with the front end face side. Therefore, the area of ​​the first and second grooves on the rear end face side can be reduced. As a result, the first length ratio associated with the first cutting blade located on the rear end face side of the first groove can be made longer than the second length ratio associated with the second cutting blade. That is, the volume ratio of the part of the main body supporting the first cutting blade can be made larger than the volume of the part of the main body supporting the second cutting blade. As a result, compared with the situation where the first and second grooves have roughly the same width throughout the entire extension direction, the rigidity of the main body can be improved by increasing the volume of the main body. Therefore, chatter during cutting can be suppressed.

[0030] (2) In the cutting tool of (1), when the main body is viewed from a direction perpendicular to the rotation axis and parallel to the second setting surface, the angle formed by the line segment connecting the center of the first setting surface and the center of the second setting surface and the rotation axis may be set as the blade configuration angle. When the main body is viewed from a direction perpendicular to the rotation axis and parallel to the second setting surface, at the upper end of the side wall of the first groove located further forward in the rotation direction than the first setting surface, the angle formed by the line segment connecting the first point whose position along the rotation axis is the same as the center of the first setting surface and the second point whose position along the rotation axis is the same as the center of the second setting surface may be set as the groove angle. In this case, the groove angle may be larger than the blade configuration angle.

[0031] In this case, the upper end of the side wall of the first groove approaches the first and second cutting inserts as it approaches the rear end face of the main body. As a result, the width of the first groove narrows toward the rear end face. Therefore, the volume of the portion of the main body supporting the first cutting insert can be easily increased compared to the volume of the portion of the main body supporting the second cutting insert.

[0032] (3) In the cutting tool of (1) or (2) above, when the main body is viewed from a direction perpendicular to the rotation axis and parallel to the first setting surface, the shortest distance from the center of the first setting surface to the upper end of the side wall of the first groove located on the front side of the main body in the rotation direction relative to the first setting surface may be set as the first width. When the main body is viewed from a direction perpendicular to the rotation axis and parallel to the second setting surface, the shortest distance from the center of the second setting surface to the upper end of the side wall of the first groove may be set as the second width. The first width may be smaller than the second width.

[0033] In this case, the width of the first groove at the portion where the first cutting blade is disposed (the first width) is smaller than the width of the first groove at the portion where the second cutting blade is disposed (the second width). Therefore, the volume of the portion of the main body supporting the first cutting blade can be easily made larger than the volume of the portion of the main body supporting the second cutting blade.

[0034] (4) The cutting tool of (1) to (3) above may further have four or more cutting blades, which are arranged inside the first groove and each of which is arranged on four or more setting surfaces. The four or more cutting blades may include a first cutting blade and a second cutting blade. The first cutting blade may be set on the first setting surface. The second cutting blade may be set on the second setting surface. Each of the four or more cutting blades may have a rake surface facing the front side of the rotation direction of the main body and a clearance surface connected to the rake surface on the side of the main body. The ridge line of each of the rake surface and the clearance surface may be a cutting edge. When the main body is observed from a direction perpendicular to the rotation axis and parallel to the first setting surface, the angle formed by the tangent of the front end face side of the cutting edge of the first cutting blade and the rotation axis may be set as the first axial rake angle. When the main body is observed from a direction perpendicular to the rotation axis and parallel to the second setting surface, the angle formed by the tangent of the front end face side of the cutting edge of the second cutting blade and the rotation axis may be set as the second axial rake angle. In this case, the first axial rake angle may be smaller than the second axial rake angle.

[0035] In this case, by reducing the axial rake angle of the first cutting insert located on the rear end face side of the first groove, the chips are more likely to flow toward the front end face side of the main body, resulting in the suppression of burr formation. In addition, the chips are less likely to clog in the area on the rear end face side of the first groove, thereby suppressing chip clogging and suppressing the generation of burrs.

[0036] (5) In the cutting tool of (1) to (4) above, the first groove may intersect the front end surface. The edge of the first groove on the front end surface may be a curved shape convex toward the rotation axis. The edge may include a first region located closer to the four or more installation surfaces and a second region located farther from the four or more installation surfaces than the first region. The curvature of the first region may be greater than the curvature of the second region.

[0037] In this case, on the front end surface side of the main body, chips generated by cutting with the cutting insert can be quickly flowed along the inner surface of the first groove. Therefore, clogging of chips on the front end surface side of the main body can be suppressed.

[0038] [Details of Implementation Methods]

[0039] The details of the embodiment of the present invention will be described with reference to the accompanying drawings. In the following drawings, the same reference numerals are used for the same or corresponding parts, and no repeated description is given. (Embodiment 1)

[0040] <Cutting tool structure>

[0041] Figure 1 It is a perspective schematic diagram of the cutting tool according to the first embodiment of the present invention. Figure 2 and Figure 4 yes Figure 1 A schematic side view of the cutting tool is shown. Figure 3 yes Figure 2 Schematic diagram of the cross section at line segment III-III. Figure 5 yes Figure 4 Schematic diagram of the cross section at the line segment V-V.

[0042] Figure 6 Viewed from the front side Figure 1 A schematic front view of the cutting tool is shown. Figure 7 It is used for Figure 1 A side view schematically illustrating the structure of a cutting tool is shown. Figure 8 It is used for Figure 1 A side schematic diagram illustrating the axial rake angle of the cutting tool is shown. Figure 9 It is used for Figure 1 A side schematic diagram illustrating the axial rake angle of the cutting tool is shown.

[0043] like Figures 1 to 9As shown, a cutting tool 1 according to one embodiment of the present invention includes a main body 10 and four or more cutting inserts 50. The main body 10 has a generally cylindrical shape. The main body 10 is rotatable about a rotation axis 10a. The main body 10 includes a front end face 10b, a rear end face 10c, and a side face 10e. The rear end face 10c is located opposite the front end face 10b. The side face 10e is an outer peripheral surface connecting the front end face 10b and the rear end face 10c.

[0044] A plurality of spiral grooves 20 are formed on the side surface 10e of the main body 10. Specifically, a first groove 20a, a second groove 20b, and a third groove 20c are formed on the side surface 10e. The second groove 20b is adjacent to the rear side of the main body 10 in the rotation direction RD at a distance when viewed from the first groove 20a. The third groove 20c is adjacent to the front side of the main body 10 in the rotation direction RD at a distance when viewed from the first groove 20a. Figures 1 to 9 The cutting insert 1 shown has three grooves 20 formed in the main body 10 , but the number of the grooves 20 may be four or more, or may be two.

[0045] In each of the first groove 20a, the second groove 20b, and the third groove 20c, there are four or more cutting inserts 50. Inside the first groove 20a, the four or more cutting inserts 50 include the first cutting insert 51 and the second cutting insert 52 arranged from the third end surface 10b side of the main body 10.

[0046] like Figure 1 As shown in the figure, the first cutting blade 51 is located closest to the rear end face 10c among the four or more cutting blades 50. The second cutting blade 52 is located closer to the front end face 10b than the first cutting blade 51. In the cutting tool 1 shown in the figure, the second cutting blade 52 is the cutting blade arranged second from the rear end face 10c.

[0047] A plurality of setting surfaces for setting the cutting blade 50 are formed on the inner surface of the first groove 20a. The plurality of setting surfaces can be planar. The plurality of setting surfaces are formed so as to face the front side of the first groove 20a and the main body 10 in the rotation direction RD. Specifically, the first setting surface 10da is formed in the area on the side of the rear end surface 10c of the first groove 20a. The first cutting blade 51 is set on the first setting surface 10da of the main body 10. Specifically, a fixing hole 2 as a screw hole is formed on the first setting surface 10da. The fixing hole 2 is formed to extend in the direction (circumferential direction) along the rotation direction RD of the main body 10. A through hole for inserting the fixing screw 30 is formed on the first cutting blade 51. On the first setting surface 10da, the first cutting blade 51 is arranged in a manner such that the through hole and the fixing hole 2 overlap. The fixing screw 30 is inserted into the fixing hole 2 via the through hole of the first cutting blade 51 and fixed to the fixing hole 2. As described above, the first cutting insert 51 is fixed to the first installation surface 10 da by the fixing screw 30 .

[0048] The first groove 20a has a second setting surface 10db formed on the front end surface 10b side relative to the first setting surface 10da. The second cutting insert 52 is provided on the second setting surface 10db of the main body 10.

[0049] Figure 3 1 is a schematic cross-sectional view of the cutting tool 1 taken along a first cross section passing through the center 2a of the first setting surface 10da and perpendicular to the rotation axis 10a. Figure 3 As shown, the length from the first mounting surface 10da to the second groove 20b of the main body 10 along the circumferential direction of rotation RD is defined as the first length L1. Specifically, consider a cross section passing through the center 2a of the first mounting surface 10da and perpendicular to the rotation axis 10a. In this cross section, the intersection of a half-line passing through the center 2a of the first mounting surface 10da and extending outward from the rotation axis 10a toward the side surface 10e is defined as the starting point 10ea, and the outermost periphery of the trajectory of the side surface 10e when the main body 10 rotates about the rotation axis 10a. Furthermore, the aforementioned center 2a is defined as the center point of the fixing hole 2 in the first mounting surface 10da. Furthermore, in the aforementioned cross section, the intersection of a line segment connecting the intersection line (intersection point 20ba) of the side wall of the second groove 20b (the side wall on the first groove 20a side) with the side surface 10e of the main body 10 and the rotation axis 10a is defined as the end point 10eb. In this cross section, the length along the side surface 10e from the starting point 10ea to the end point 10eb is defined as the first length L1. Furthermore, as an indicator of the length from the starting point 10ea to the end point 10eb, the angle (center angle θ1) formed by the line segment connecting the rotation axis 10a and the center 2a and the line segment connecting the rotation axis 10a and the intersection 20ba in the cross section can be used.

[0050] Figure 5 1 is a schematic cross-sectional view of the cutting tool 1 taken along a second cross section passing through the center 2a of the second setting surface 10db and perpendicular to the rotation axis 10a. Figure 5 As shown, the length from the second mounting surface 10db to the second groove 20b of the main body 10 along the circumferential direction of rotation RD is defined as the second length L2. Specifically, consider a cross section passing through the center 2a of the second mounting surface 10db and perpendicular to the rotation axis 10a. In this cross section, the intersection of a half-line passing through the center 2a of the second mounting surface 10db and extending outward from the rotation axis 10a toward the side surface 10e is defined as the starting point 10ea, and the outermost periphery of the trajectory of the side surface 10e when the main body 10 rotates about the rotation axis 10a. Furthermore, the aforementioned center 2a is defined as the center point of the fixing hole 2 of the second mounting surface 10db. Furthermore, in the aforementioned cross section, the intersection of a line segment connecting the intersection line (intersection point 20ba) of the side wall of the second groove 20b (the side wall on the first groove 20a side) with the side surface 10e of the main body 10 and the rotation axis 10a is defined as the end point 10eb. In this cross section, the length along the side surface 10e from the starting point 10ea to the end point 10eb is defined as the second length L2. Furthermore, as an indicator of the length from the starting point 10ea to the end point 10eb, the angle (center angle θ2) formed by the line segment connecting the rotation axis 10a and the center 2a and the line segment connecting the rotation axis 10a and the intersection 20ba in the cross section can be used.

[0051] exist Figures 1 to 5 In the cutting tool 1 shown, the first length L1 is longer than the second length L2. Furthermore, the central angle θ1 is greater than the central angle θ2. Furthermore, the length relationship (the relationship between the first length L1 and the second length L2) of the portion of the main body 10 adjacent to the first cutting insert 51 and the second cutting insert 52 provided in the first groove 20a also holds true for the cutting inserts 50 provided in the other grooves 20.

[0052] like Figure 1 and Figure 6 As shown in FIG. 1 , in the cutting tool 1 , the first groove 20a intersects the front end face 10b. When the front end face 10b is viewed along the rotation axis 10a, the edge 21 of the first groove 20a of the front end face 10b is a curved shape convex toward the rotation axis 10a. Specifically, as shown in FIG. Figure 6As shown, the edge 21 includes a first region 21a and a second region 21b. The first region 21a is located on the side closer to the multiple setting surfaces 10d inside the first groove 20a. The second region 21b is located on the side farther away from the multiple setting surfaces 10d inside the first groove 20a than the first region 21a. From another point of view, the first region 21a is located on the side closer to the multiple cutting blades 50 arranged in the first groove 20a. The second region 21b is located on the opposite side of the multiple cutting blades 50 when viewed from the first region 21a. The curvature of the first region 21a is greater than the curvature of the second region 21b. In addition, the first region 21a is arranged in a region closer to the rotation axis 10a than the second region 21b.

[0053] When the front end face 10b is observed along the rotation axis 10a, the shape of the edge 21 has a corresponding curvature when a certain point of the edge 21 is determined. The shape of the first region 21a may have substantially the same curvature for all points in the first region 21a. The shape of the first region 21a may have different curvatures corresponding to the points on the first region 21a. Similarly, the shape of the second region 21b may have substantially the same curvature for all points in the second region 21b. Similarly, the shape of the second region 21b may have different curvatures corresponding to the points on the second region 21b. In this specification, the "curvature" of the first region 21a refers to the range of curvature values ​​corresponding to all points on the first region 21a. Similarly, in this specification, the "curvature" of the second region 21b refers to the range of curvature values ​​corresponding to all points on the second region 21b.

[0054] Figure 7 This is a side view of the cutting tool 1 viewed from a direction perpendicular to the rotation axis 10a and parallel to the second setting surface 10db. Figure 7 As shown, in the cutting tool 1, the direction in which the plurality of cutting inserts 50 are arranged in one groove 20 is different from the extending direction of the side wall upper end 24 of the groove 20 that is located forward of the cutting inserts 50 in the rotation direction RD. From a different perspective, the cutting tool 1 has the following features.

[0055] like Figure 7 As shown in FIG. 1 , consider the case where the main body 10 is viewed from a direction perpendicular to the rotation axis 10a and parallel to the second setting surface 10db. The center 10daa of the first setting surface 10da on which the first cutting blade 51 is disposed is determined. The center 10daa can be set to Figure 3 The center 2a of the fixing hole 2 of the first setting surface 10da shown in FIG. The center 10dba of the second setting surface 10db on which the second cutting blade 52 is arranged is determined. The center 10dba can be set to Figure 5The center 2a of the fixing hole 2 of the second setting surface 10db is shown. The angle formed by the line segment 55 connecting the center 10daa of the first setting surface 10da and the center 10dba of the second setting surface 10db and the rotation axis 10a is defined as the blade arrangement angle θ4.

[0056] When viewing the main body 10 from a direction perpendicular to the rotation axis 10a and parallel to the second installation surface 10db, a first point 24a is identified at the upper end 24 of the side wall of the first groove 20a, located further forward in the rotation direction RD than the first installation surface 10da. A second point 24b is identified at the same position along the rotation axis 10a as the center 10dba of the second installation surface 10db. The angle formed by the line segment 25 connecting the first point 24a and the second point 24b and the rotation axis 10a is defined as groove angle θ3. Groove angle θ3 is greater than blade arrangement angle θ4.

[0057] Figure 8 It is a schematic side view of the cutting tool 1 as viewed from a direction perpendicular to the rotation axis 10 a and parallel to the first installation surface 10 da . Figure 9 This is a side view of the cutting tool 1 as viewed from a direction perpendicular to the rotation axis 10a and parallel to the second setting surface 10db. In the above-mentioned cutting tool 1, the distance between the plurality of cutting blades 50 and the upper end 24 of the side wall of the above-mentioned groove 20 becomes smaller as it moves toward the rear end surface 10c of the main body 10. From a different point of view, in the above-mentioned cutting tool 1, the distance from the first setting surface 10da to the upper end 24 of the side wall is different from the distance from the second setting surface 10db to the upper end 24 of the side wall. That is, as Figure 8 As shown, the shortest distance from the center 10daa of the first installation surface 10da to the upper end 24 of the side wall of the first groove 20a located further forward than the first installation surface 10da in the rotation direction RD of the main body 10 is defined as the first width W1. Figure 9 As shown in FIG. 1 , the shortest distance from the center 10dba of the second installation surface 10db to the upper end 24 of the side wall of the first groove 20a is defined as the second width W2. The first width W1 is smaller than the second width W2.

[0058] The cutting tool 1 is as Figure 3 As shown, there is a third cutting blade 53, which is arranged inside the third groove 20c and is arranged to overlap with the first cutting blade 51 in the direction of the rotation axis 10a. Figure 5 As shown, the cutting tool 1 includes a fourth cutting insert 54 . The fourth cutting insert 54 is disposed inside the third groove 20 c and is disposed so as to overlap with the second cutting insert 52 in the direction along the rotation axis 10 a .

[0059] The cutting tool 1 is as Figure 3 As shown, there is a fifth cutting blade 56, which is arranged inside the second groove 20b and is arranged to overlap with the first cutting blade 51 in the direction of the rotation axis 10a. Figure 5 As shown, the cutting tool 1 includes a sixth cutting blade 57, which is arranged inside the second groove 20b and is positioned so as to overlap with the second cutting blade 52 in the direction of the rotation axis 10a. The length relationship of the portion of the main body 10 adjacent to the third cutting blade 53 and the fourth cutting blade 54 arranged in the third groove 20c (corresponding to the relationship between the first length L1 and the second length L2) is the same as the length relationship of the portion of the main body 10 adjacent to the first cutting blade 51 and the second cutting blade 52 arranged in the first groove 20a. In addition, the length relationship of the portion of the main body 10 adjacent to the fifth cutting blade 56 and the sixth cutting blade 57 arranged in the second groove 20b (corresponding to the relationship between the first length L1 and the second length L2) is the same as the length relationship of the portion of the main body 10 adjacent to the first cutting blade 51 and the second cutting blade 52 arranged in the first groove 20a.

[0060] like Figure 8 and Figure 9 As shown, in the cutting tool 1, each of the multiple cutting inserts 50 has a rake surface 50b facing forward in the rotational direction RD of the main body 10 and a relief surface 50c connected to the rake surface 50b on the side surface 10e of the main body 10. The ridge lines of the rake surface 50b and the relief surface 50c form the cutting edge 50a. When the main body 10 is viewed from a direction perpendicular to the rotation axis 10a and parallel to the first mounting surface 10da, the angle formed by the tangent line on the front end surface 10b side of the cutting edge 50a of the first cutting insert 51 and the rotation axis 10a can be defined as the first axial rake angle θ5. When the main body 10 is viewed from a direction perpendicular to the rotation axis 10a and parallel to the second mounting surface 10db, the angle formed by the tangent line on the front end surface 10b side of the cutting edge 50a of the second cutting insert 52 and the rotation axis 10a can be defined as the second axial rake angle θ6. In this case, the first axial rake angle θ5 is smaller than the second axial rake angle θ6.

[0061] Effects

[0062] In the cutting tool 1, the length from the first installation surface 10da on which the first cutting blade 51 is arranged to the second groove 20b in the circumferential direction along the rotation direction RD of the main body 10 is set as the first length L1. The length from the second installation surface 10db on which the second cutting blade 52 is arranged to the second groove 20b in the circumferential direction is set as the second length L2. In the cutting tool 1, the first length L1 is configured to be longer than the second length L2.

[0063] With this configuration, the volume of the portion of the main body 10 that supports the first cutting insert 51 (the portion of the main body 10 that supports the first cutting insert 51 from the rear side in the rotational direction RD of the main body 10) can be made larger than the volume of the portion of the main body 10 that supports the second cutting insert 52. As a result, compared to a case where the first groove 20a and the second groove 20b have substantially the same width throughout the entire extension direction, the rigidity of the main body 10 can be improved by increasing the volume of the main body 10. Consequently, chatter vibration during cutting can be suppressed.

[0064] In the above-mentioned cutting tool 1, as Figure 7 As shown, the groove angle θ3 is greater than the blade configuration angle θ4. In this case, the closer the upper end 24 of the side wall of the first groove 20a is to the rear end face 10c of the main body 10, the closer it is to the first cutting blade 51 and the second cutting blade 52. As a result, the width of the first groove 20a becomes narrower as it moves toward the rear end face 10c. Therefore, the volume of the portion of the main body 10 supporting the first cutting blade 51 can be easily made larger than the volume of the portion of the main body 10 supporting the second cutting blade 52. As a result, the rigidity of the main body 10 can be improved.

[0065] In the above-mentioned cutting tool 1, as Figure 8 As shown, the shortest distance from the center 10daa of the first installation surface 10da to the upper end 24 of the side wall of the first groove 20a located further forward than the first installation surface 10da in the rotation direction RD of the main body 10 is defined as the first width W1. Figure 9 As shown, the shortest distance from the center 10dba of the second setting surface 10db to the upper end 24 of the side wall of the first groove 20a is set to the second width W2. The first width W1 is smaller than the second width W2. In this case, the width (first width W1) of the first groove 20a at the portion where the first cutting blade 51 is arranged is smaller than the width (second width W2) of the first groove 20a at the portion where the second cutting blade 52 is arranged. Therefore, it is easy to make the volume of the portion of the main body 10 that supports the first cutting blade 51 larger than the volume of the portion of the main body 10 that supports the second cutting blade 52. As a result, the rigidity of the main body 10 can be improved.

[0066] The cutting tool 1 has a third groove 20c formed in the side surface 10e of the main body 10. The third groove 20c is adjacent to the front side of the main body 10 in the rotational direction RD when viewed from the first groove 20a. The cutting tool 1 includes a third cutting insert 53, which is arranged within the third groove 20c so as to overlap with the first cutting insert 51 along the direction of the rotation axis 10a. The cutting tool 1 includes a fourth cutting insert 54, which is arranged within the third groove 20c so as to overlap with the second cutting insert 52 along the direction of the rotation axis 10a.

[0067] In this case, the volume of the portion of the main body 10 supporting the third cutting insert 53 can be made larger than the volume of the portion of the main body 10 supporting the fourth cutting insert 54. Therefore, the rigidity of the main body 10 can be improved.

[0068] In the cutting tool 1 described above, the first axial rake angle θ5 associated with the rake surface 50b of the first cutting insert 51 is smaller than the second axial rake angle θ6 associated with the rake surface 50b of the second cutting insert 52. In this case, by reducing the first axial rake angle θ5 of the first cutting insert 51 located on the rear end face 10c side of the first groove 20a, chips are more likely to flow toward the front end face 10b of the main body 10, thereby suppressing the formation of burrs. Furthermore, since chips are less likely to clog in the area on the rear end face 10c side of the first groove 20a, chip clogging can be suppressed, thereby suppressing the formation of burrs.

[0069] In the cutting tool 1, the edge 21 of the first groove 20a on the front end surface 10b is curved and convex toward the rotation axis 10a. The curvature of the first region 21a of the edge 21 is greater than the curvature of the second region 21b.

[0070] In this case, chips generated by cutting with the cutting insert 50 can flow quickly along the inner surface of the first groove 20a on the front end surface 10b of the main body 10. Therefore, clogging of the front end surface of the main body 10 by chips can be suppressed.

[0071] (Implementation Method 2)

[0072] Figure 10 It is a perspective schematic diagram of a cutting tool according to a second embodiment of the present invention. Figure 11 and Figure 13 yes Figure 10 A schematic side view of the cutting tool is shown. Figure 12 yes Figure 11 Schematic diagram of the cross section at line segment XII-XII. Figure 14 yes Figure 13 Schematic diagram of the cross section at line segment XIV-XIV. Figure 15 Viewed from the front side Figure 10 A schematic front view of the cutting tool is shown.

[0073] Figures 10 to 15 The cutting tool 1 shown has essentially the same Figures 1 to 9 The structure of the cutting tool 1 shown in FIG. 1 is the same as that of the cutting tool 1 shown in FIG. 1 , but the shape of the groove 20 of the main body 10, the structure of the cutting insert 50 arranged in the groove 20, and the method of fixing the cutting insert 50 to the main body 10 are different from those of FIG. Figures 1 to 9 The cutting tool 1 shown is different.

[0074] like Figures 10 to 15 As shown, a plurality of spiral grooves 20 are formed on the side surface 10e of the main body 10. The plurality of grooves 20 are each separated into a portion on the front end surface 10b side of the main body 10 (front end side groove 201) and a rear end side groove 202 spaced apart from the front end side groove. Specifically, a first groove 20a, a second groove 20b, and a third groove 20c are formed on the side surface 10e. The first groove 20a includes a front end side groove 201a and a rear end side groove 202a. In addition, Figures 10 to 15 The cutting insert 1 shown has three grooves 20 formed in the main body 10 , but the number of the grooves 20 may be four or more, or may be two.

[0075] More than four cutting blades 50 are respectively arranged in the first groove 20a, the second groove 20b, and the third groove 20c. Specifically, for example, one cutting blade 50 is arranged in the front end side groove 201a of the first groove 20a. Four cutting blades 50 are arranged in the rear end side groove 202a of the first groove 20a. In addition, the number of cutting blades 50 arranged in the rear end side groove 202a can be more than five or less than three. The number of cutting blades 50 arranged in the front end side groove 201a can be more than two. Inside the first groove 20a, the more than four cutting blades 50 include the first cutting blade 51 and the second cutting blade 52 arranged from the third onward from the front end surface 10b side of the main body 10.

[0076] like Figure 10 As shown in the figures, the first cutting blade 51 is located closest to the rear end face 10c in the rear end groove 202a among the four or more cutting blades 50. The second cutting blade 52 is located closer to the front end face 10b than the first cutting blade 51. In the cutting tool 1 shown in the figures, the second cutting blade 52 is the second cutting blade from the rear end face 10c and the fourth cutting blade from the front end face 10b.

[0077] The inner surface of the first groove 20a is formed with a plurality of setting surfaces for setting the cutting insert 50. The plurality of setting surfaces 10d are formed to face the radial outer side of the first groove 20a and the main body 10. Specifically, in the area on the rear end surface 10c side of the first groove 20a, as shown in FIG. Figure 12 As shown, a first setting surface 10da is formed. The first setting surface 10da is configured to face the radially outer side of the main body 10. The first cutting blade 51 is provided on the first setting surface 10da of the main body 10. Specifically, a fixing hole 2 as a screw hole is formed on the first setting surface 10da. The fixing hole 2 is formed to extend in the direction (radially) toward the rotation axis 10a of the main body 10. A through hole for inserting the fixing screw 30 is formed in the first cutting blade 51. On the first setting surface 10da, the first cutting blade 51 is configured in such a manner that the through hole overlaps with the fixing hole 2. The fixing screw 30 is inserted into and fixed to the fixing hole 2 through the through hole of the first cutting blade 51. As described above, the first cutting blade 51 is fixed to the first setting surface 10da by the fixing screw 30 configured in a radially extending manner.

[0078] The first groove 20a has a second mounting surface 10db formed on the front end face 10b side relative to the first mounting surface 10da. Like the first mounting surface 10da, the second mounting surface 10db is disposed so as to face the radially outer side of the main body 10. The second cutting insert 52 is mounted on the second mounting surface 10db of the main body 10. The second cutting insert 52 is secured to the second mounting surface 10db in the same manner as the first cutting insert 51 is secured to the first mounting surface 10da.

[0079] Figure 12 1 is a schematic cross-sectional view of the cutting tool 1 taken along a first cross section passing through the center 2a of the first setting surface 10da and perpendicular to the rotation axis 10a. Figure 12As shown, the length from the first mounting surface 10da to the second groove 20b of the main body 10 along the circumferential direction of rotation RD is defined as first length L1. Specifically, consider a cross section passing through the center 2a of the first mounting surface 10da and perpendicular to the rotation axis 10a. In this cross section, the intersection of a half-line extending from the rotation axis 10a through the center 2a of the first mounting surface 10da toward the outside of the side surface 10e and the outermost periphery of the trajectory of the side surface 10e when the main body 10 rotates about the rotation axis 10a is defined as starting point 10ea. Furthermore, the aforementioned center 2a is defined as the center point of the fixing hole 2 in the first mounting surface 10da. In the cross section, the intersection of the line segment connecting the intersection line (intersection point 20ba) and the rotation axis 10a with the outermost periphery of the trajectory of the side surface 10e is defined as the end point 10eb. This intersection line (intersection point 20ba) is the intersection line between the side wall of the second groove 20b (the side wall on the first groove 20a side) and the side surface 10e of the main body 10. In this cross section, the length along the side surface 10e from the starting point 10ea to the end point 10eb is defined as the first length L1. Furthermore, as an indicator of the length from the starting point 10ea to the end point 10eb, the angle (center angle θ1) formed by the line segment connecting the rotation axis 10a and the center 2a and the line segment connecting the rotation axis 10a and the intersection point 20ba in the cross section can be used.

[0080] Figure 14 1 is a schematic cross-sectional view of the cutting tool 1 taken along a second cross section passing through the center 2a of the second setting surface 10db and perpendicular to the rotation axis 10a. Figure 14As shown, the length from the second mounting surface 10db to the second groove 20b of the main body 10 along the circumferential direction of rotation RD is defined as the second length L2. Specifically, consider a cross section passing through the center 2a of the second mounting surface 10db and perpendicular to the rotation axis 10a. In this cross section, the intersection of a half-line extending from the rotation axis 10a through the center 2a of the second mounting surface 10db toward the outside of the side surface 10e is defined as the starting point 10ea, and the outermost periphery of the trajectory of the side surface 10e when the main body 10 rotates about the rotation axis 10a. Furthermore, the aforementioned center 2a is defined as the center point of the fixing hole 2 in the second mounting surface 10db. In the cross section, the intersection of the line segment connecting the intersection line (intersection point 20ba) and the rotation axis 10a with the outermost periphery of the trajectory of the side surface 10e is defined as the end point 10eb. This intersection line (intersection point 20ba) is the intersection line between the side wall of the second groove 20b (the side wall on the first groove 20a side) and the side surface 10e of the main body 10. In this cross section, the length along the side surface 10e from the starting point 10ea to the end point 10eb is defined as the second length L2. Furthermore, as an indicator of the length from the starting point 10ea to the end point 10eb, the angle (center angle θ2) formed by the line segment connecting the rotation axis 10a and the center 2a and the line segment connecting the rotation axis 10a and the intersection point 20ba in the cross section can be used.

[0081] exist Figures 10 to 14 In the cutting tool 1 shown, the first length L1 is longer than the second length L2. Furthermore, the central angle θ1 is greater than the central angle θ2. Furthermore, the relationship between the lengths of the portion of the main body 10 adjacent to the first cutting insert 51 and the second cutting insert 52 provided in the first groove 20a (the relationship between the first length L1 and the second length L2) also holds true for the cutting inserts 50 provided in the other grooves 20.

[0082] like Figure 10 and Figure 15 As shown in FIG. 1 , in the cutting tool 1 , the front end side groove 201a of the first groove 20a intersects the front end face 10b. When the front end face 10b is viewed along the rotation axis 10a, the edge 21 of the first groove 20a (front end side groove 201a) of the front end face 10b includes a curved portion that bulges toward the rotation axis 10a. Specifically, Figure 15As shown, the edge 21 includes a first region 21a and a second region 21b. The first region 21a is located on the side closer to the multiple setting surfaces 10d inside the first groove 20a. The second region 21b is located on the side farther away from the multiple setting surfaces 10d inside the first groove 20a than the first region 21a. From another point of view, the first region 21a is located on the side closer to the multiple cutting blades 50 arranged in the first groove 20a. The first region 21a has a curved shape that protrudes toward the rotation axis 10a. The second region 21b is located on the opposite side of the multiple cutting blades 50 arranged in the first groove 20a when viewed from the first region 21a. The second region 21b has a substantially straight shape. The curvature of the first region 21a is greater than the curvature of the second region 21b. In addition, the first region 21a includes a portion that is closer to the rotation axis 10a than the second region 21b.

[0083] The cutting tool 1 is as Figure 12 As shown, there is a third cutting blade 53, which is arranged inside the third groove 20c and is arranged to overlap with the first cutting blade 51 in the direction of the rotation axis 10a. Figure 14 As shown, the cutting tool 1 includes a fourth cutting insert 54 . The fourth cutting insert 54 is disposed inside the third groove 20 c and is disposed so as to overlap with the second cutting insert 52 in the direction along the rotation axis 10 a .

[0084] The cutting tool 1 is as Figure 12 As shown, there is a fifth cutting blade 56, which is arranged inside the second groove 20b and is arranged to overlap with the first cutting blade 51 in the direction of the rotation axis 10a. Figure 14 As shown, the cutting tool 1 includes a sixth cutting blade 57, which is arranged inside the second groove 20b and is positioned so as to overlap with the second cutting blade 52 in the direction of the rotation axis 10a. The length relationship of the portion of the main body 10 adjacent to the third cutting blade 53 and the fourth cutting blade 54 arranged in the third groove 20c (corresponding to the relationship between the first length L1 and the second length L2) is the same as the length relationship of the portion of the main body 10 adjacent to the first cutting blade 51 and the second cutting blade 52 arranged in the first groove 20a. In addition, the length relationship of the portion of the main body 10 adjacent to the fifth cutting blade 56 and the sixth cutting blade 57 arranged in the second groove 20b (corresponding to the relationship between the first length L1 and the second length L2) is the same as the length relationship of the portion of the main body 10 adjacent to the first cutting blade 51 and the second cutting blade 52 arranged in the first groove 20a.

[0085] pass Figures 10 to 15 The cutting tool 1 shown can also be obtained with Figures 1 to 9 The same effect is achieved with the cutting tool 1 shown.

[0086] (Example 1)

[0087] An experiment was conducted to investigate the effect of suppressing chatter vibration.

[0088] <Device and Sample>

[0089] A vertical machining center (NVX5080, spindle size BBT50, manufactured by DMG Mori Seiki Co., Ltd.) was used for the test.

[0090] The workpiece used was S50C, classified as carbon steel S-C according to Japanese Industrial Standard (JIS) G4051:2016. To ensure sufficient rigidity during cutting, the workpiece was square. The workpiece dimensions were 85 mm × 100 mm × 300 mm. The workpiece was secured by gripping the sides with a vise.

[0091] The tool used was a shank type with a tool diameter of φ32mm, an effective blade length of 35mm, 3 effective blades, a total number of blades of 12, and a shank diameter of φ32mm. As a cutting insert, a general-purpose cutting insert model AOMT11T308PEER-G manufactured by Sumitomo Electric Hardmetal Co., Ltd. was used. The tool of the embodiment has Figures 1 to 9 In addition, as a comparative example, a tool other than Figure 3 The central angle θ1 and Figure 5 The tool has the same structure as the tool of the above-described embodiment except that the center angle θ2 shown is the same.

[0092] <Test method>

[0093] Figure 16 This is a schematic diagram used to illustrate the test method. Figure 16 As shown, a test was conducted using the cutting tools of the examples and comparative examples to cut a workpiece 100. Cutting conditions included a rotational speed of 150 m / min, a feed rate of 0.1 mm / tip, and an axial depth of cut 101 of 30 mm. The radial depth of cut 102 was initially set at 5 mm and increased in 5 mm increments until chatter vibration occurred. The tool protrusion length from the retainer was set at 60 mm.

[0094] As a cutting method, such as Figure 16 The following example shows the down milling method. The oil supply method (coolant supply method) during cutting is set to dry type.

[0095] As a criterion for determining whether or not chattering occurs, whether or not a loud sound is produced is used as a criterion. If a loud sound is produced, it is determined that chattering occurs.

[0096] Under the above-mentioned cutting conditions, the radial cutting depth at which chatter vibration occurs was compared using the tool of the embodiment and the tool of the comparative example.

[0097] Results

[0098] The comparative example tool did not experience chatter at radial depths of cut of 5 mm, 10 mm, or 15 mm. However, chatter did occur at a radial depth of cut of 20 mm, and the occurrence of chatter became significant at a radial depth of cut of 25 mm.

[0099] On the other hand, the tool of the embodiment did not experience chatter at radial depths of cut of 5 mm, 10 mm, 15 mm, and 20 mm. Chatter did occur at a radial depth of cut of 25 mm, and the occurrence of chatter became significant at a radial depth of cut of 30 mm.

[0100] As described above, the tool of the embodiment is less likely to cause chatter than the tool of the comparative example, and can be used in a larger radial depth of cut, thereby exhibiting high chatter resistance.

[0101] (Example 2)

[0102] Experiments were conducted on the relationship between burr generation and axial tilt angle.

[0103] <Device and Sample>

[0104] The test used the same vertical machining center as in Example 1. In addition, as the workpiece, a workpiece having the same material and shape as the workpiece used in Example 1 was used.

[0105] The tool used was a shank type tool with a tool diameter of φ25 mm and a shank diameter of φ25 mm. Tool 1 with a cutting insert having an axial rake angle of 16° and tool 2 with an axial rake angle of -1° were prepared.

[0106] As the cutting insert, a general-purpose cutting insert of model number AOMT11T308PEER-G manufactured by Sumitomo Electric Hardmetal Co., Ltd. was used.

[0107] <Test method>

[0108] Cutting conditions included a rotational speed of 200 m / min, a feed rate of 0.1 mm / edge, an axial depth of cut of 15 mm, and a radial depth of cut of 2 mm. The tool protrusion length from the holder was 63 mm.

[0109] The cutting method was down milling as in Example 1. The oil supply method during cutting was dry.

[0110] Under the above-mentioned cutting conditions, the workpiece was cut using the tool 1 and the tool 2. Then, the sizes of the burrs on the upper surfaces of the workpieces were compared.

[0111] Results

[0112] When the tool 2 was used, the generation of burrs visually confirmed was suppressed compared to the case of the tool 1. Therefore, it was shown that the burrs were suppressed by reducing the axial rake angle.

[0113] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The basic scope of the present invention is not represented by the above-described embodiments but by the claims, and the scope of the present invention includes all modifications within the meaning and scope equivalent to the claims.

[0114] Description of the label

[0115] 1 cutting tool, 2 fixing hole, 2a, 10daa, 10dba center, 10 main body, 10a rotation axis, 10b front end surface, 10c rear end surface, 10d setting surface, 10da first setting surface, 10db second setting surface, 10e side surface, 10ea starting point, 10eb end point, 20 groove, 20a first groove, 20b second groove, 20ba intersection, 20c third groove, 21 edge, 21a first area, 21b second area, 24 side wall upper end, 24a first point, 24b second point, 25, 55 line segments, 30 fixing screw, 50 cutting blade, 50 a cutting edge, 50b rake surface, 50c clearance surface, 51 1st cutting blade, 52 2nd cutting blade, 53 3rd cutting blade, 54 4th cutting blade, 56 5th cutting blade, 57 6th cutting blade, 100 cut material, 101 axial depth of cut, 102 radial depth of cut, 201, 201a front end side groove, 202, 202a rear end side groove, L1 1st length, L2 2nd length, RD rotation direction, W1 1st width, W2 2nd width, θ1, θ2 center angles, θ3 groove angle, θ4 blade configuration angle, θ5 1st axial rake angle, θ6 2nd axial rake angle.

Claims

1. A cutting tool capable of rotating about an axis of rotation, The cutting tool has a main body having a front end face, a side face connected to the front end face, and a rear end face connected to the side face and located on the opposite side to the front end face in the direction along the rotation axis. A first spiral groove and a second spiral groove are formed on the side surface of the main body. The second groove is adjacent to the rear side of the main body in the rotation direction when viewed from the first groove, The first tank has four or more installation surfaces inside. The four or more setting surfaces are used to set the cutting blades. The four or more installation surfaces include a first installation surface and a second installation surface which are arranged third and later from the front end surface side of the main body. The first installation surface is located closest to the rear end surface among the four or more installation surfaces. The second installation surface is located closer to the front end surface than the first installation surface. Each of the four or more installation surfaces has a fixing hole for fixing the cutting insert. On the four or more installation surfaces, the centers of the respective fixing holes are set as the centers of the four or more installation surfaces, In a first cross-section passing through the center of the first setting surface and perpendicular to the rotation axis, an intersection of a half-line passing through the center of the first setting surface and extending toward the outside of the side surface from the rotation axis as a starting point and the side surface is set as a first starting point. In the first cross section, an intersection point between the side wall of the second groove on the first groove side and the side surface is set as a first end point, The length of the side surface of the main body portion from the first starting point to the first end point of the first cross section is defined as a first length. In a second cross-section passing through the center of the second setting surface and perpendicular to the rotation axis, an intersection of a half-line passing through the center of the second setting surface and extending toward the outside of the side surface from the rotation axis as a starting point and the side surface is set as a second starting point. In the second cross section, an intersection point between the side wall of the second groove on the first groove side and the side surface is set as a second end point, When the length of the side surface of the main body portion from the second starting point to the second end point of the second cross section is defined as a second length, The first length is longer than the second length.

2. The cutting tool according to claim 1, wherein When the main body is viewed from a direction perpendicular to the rotation axis and parallel to the second installation surface, The angle formed by the line segment connecting the center of the first setting surface and the center of the second setting surface and the rotation axis is defined as the blade arrangement angle. At the upper end of the side wall of the first groove located further forward in the rotational direction than the first setting surface, when the angle formed by a line segment connecting a first point whose position along the direction of the rotation axis is the same as the center of the first setting surface and a second point whose position along the direction of the rotation axis is the same as the center of the second setting surface and the rotation axis is defined as a groove angle, The slot angle is greater than the blade configuration angle.

3. The cutting tool according to claim 1 or 2, wherein: When the main body is viewed from a direction perpendicular to the rotation axis and parallel to the first setting surface, the shortest distance from the center of the first setting surface to the upper end of the side wall of the first groove located further forward than the first setting surface in the rotation direction of the main body is defined as a first width. When the main body is viewed from a direction perpendicular to the rotation axis and parallel to the second installation surface, and the shortest distance from the center of the second installation surface to the upper end of the side wall of the first groove is defined as the second width, The first width is smaller than the second width.

4. The cutting tool according to claim 1 or 2, wherein: There are also four or more cutting inserts arranged inside the first groove and each of which is arranged on the four or more installation surfaces. The four or more cutting blades include a first cutting blade and a second cutting blade, The first cutting blade is arranged on the first setting surface, The second cutting blade is arranged on the second setting surface. Each of the four or more cutting inserts has a rake surface facing the front side of the main body in the rotation direction and a relief surface connected to the rake surface on the side surface of the main body. The ridge lines of the rake surface and the relief surface are cutting edges, When the main body is viewed from a direction perpendicular to the rotation axis and parallel to the first setting surface, an angle formed by a tangent line on the front end surface side of the cutting edge of the first cutting insert and the rotation axis is defined as a first axial rake angle. When the main body is viewed from a direction perpendicular to the rotation axis and parallel to the second setting surface, the angle formed by the tangent line on the front end surface side of the cutting edge of the second cutting insert and the rotation axis is defined as a second axial rake angle. The first axial rake angle is smaller than the second axial rake angle.

5. The cutting tool according to claim 1 or 2, wherein: The first groove intersects the front end surface, The edge of the first groove on the front end surface is in a curved shape convex toward the rotation axis side. The edge portion includes a first region located closer to the four or more installation surfaces and a second region located farther from the four or more installation surfaces than the first region. The curvature of the first region is greater than the curvature of the second region.

Images