Cutting tool and method for manufacturing machined product

Abstract

The cutting tool according to one mode of the present disclosure comprises: a body which extends from a leading end to a rear end along a rotational axis and which is equipped with a first pocket and a second pocket that are disposed on the side of the leading end; a first insert which is positioned in the first pocket and has a first cutting edge; and a second insert which is positioned in the second pocket and has a second cutting edge. The first insert has a positive axial rake angle, while the second insert has a negative axial rake angle.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2022-085398, filed on May 25, 2022, the entire disclosure of which is incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates to a cutting tool and a method for manufacturing a machined product. [Background technology]

[0003] A known cutting tool is the chamfering cutter described in JP 2021-74798 A (Patent Document 1). Generally, when chamfering is performed, burrs called Poisson burrs (side burrs) are generated near both ends of the chamfered surface. Poisson burrs are likely to occur near both ends of the chamfered surface, particularly on the side where the cutting edge was in contact until just before it separated from the workpiece. Therefore, for example, when chamfering is performed using an insert with a 45° cutting angle, Poisson burrs often occur near the top end of the chamfered surface if the axial rake is positive, and near the bottom end of the chamfered surface if the axial rake is negative.

[0004] The chamfering cutter described in Patent Document 1 has a V-shaped cutting edge. This V-shaped cutting edge has an inner cutting edge portion, an outer cutting edge portion, and a curved cutting portion located between them. With this configuration of the cutting edge, the flow of chips caused by cutting is directed toward the curved cutting edge portion, thereby suppressing the occurrence of Poisson burrs on the edge of the chamfered surface formed by cutting.

[0005] However, in the cutting tool described in Patent Document 1, the axial rake of one cutting edge has both a positive portion and a negative portion, so as the cutting edge wears, the chamfered surface may become convex in a cross section perpendicular to the direction of travel of the cutting tool, causing problems in terms of machining accuracy.

[0006] Furthermore, the technique of suppressing the generation of Poisson burrs by providing a curved cutting portion on the cutting edge, as in Patent Document 1, is not very versatile for so-called insert-type cutting tools. When the cutting edge has a curved cutting portion, the optimal value of the curved cutting portion that suppresses the generation of Poisson burrs varies depending on the machining diameter of the workpiece, in other words, the outer diameter of the cutting tool. As a result, there is a risk of imposing restrictions on the machining conditions. In other words, when preparing a repertoire of multiple cutting tools with different outer diameters, it is necessary to prepare an optimal insert for each cutting tool. Summary of the Invention

[0007] A cutting tool according to one embodiment of the present disclosure includes a body portion extending from a front end to a rear end along a rotation axis and having a first pocket and a second pocket, each of which is located on the front end side, a first insert located in the first pocket and having a first cutting edge, and a second insert located in the second pocket and having a second cutting edge, wherein the axial rake of the first insert is positive and the axial rake of the second insert is negative. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a cutting tool according to a first embodiment. [Figure 2] 2 is a plan view of the cutting tool shown in FIG. 1 as viewed from the X1 direction. [Figure 3] 2 is a plan view of the cutting tool shown in FIG. 1 as viewed from the X2 direction. [Figure 4] 2 is a plan view of the cutting tool shown in FIG. 1 as viewed from the X3 direction. [Figure 5] FIG. 3 is an enlarged view of an area Y1 shown in FIG. [Figure 6] FIG. 4 is an enlarged view of an area Y2 shown in FIG. [Figure 7] FIG. 5 is an enlarged view of an area Y3 shown in FIG. [Figure 8] FIG. 5 is an enlarged view of an area Y4 shown in FIG. [Figure 9] FIG. 4 is a side view showing a cutting tool according to a second embodiment. [Figure 10] FIG. 10 is an enlarged view of an area Y5 shown in FIG. [Figure 11] 10 is an enlarged view of an area Y5 shown in FIG. 9 as viewed from the X4 direction. [Figure 12] FIG. 2 is a schematic explanatory view showing one step of a method for manufacturing a machined product according to an embodiment. [Figure 13] FIG. 2 is a schematic explanatory view showing one step of a method for manufacturing a machined product according to an embodiment. [Figure 14] FIG. 2 is a schematic explanatory view showing one step of a method for manufacturing a machined product according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Cutting tools according to non-limiting first and second embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, for the sake of convenience, the drawings referred to below show only the main components necessary for explaining each embodiment in a simplified form. Therefore, the cutting tool of the present disclosure may include optional components not shown in the drawings. Furthermore, the dimensions of the components in the drawings do not faithfully represent the actual dimensions of the components, the dimensional ratios of the components, etc.

[0010] The cutting tool 1A according to the first embodiment is a so-called rotary tool that rotates in a rotation direction O2 about a rotation axis O1, as shown in a non-limiting example in FIG. 1. Examples of rotary tools include milling tools and end mills. The non-limiting example of the rotary tool shown in FIG. 1 is a milling tool.

[0011] The rotation axis O1 is an axis about which the cutting tool 1A rotates, and is not a tangible part of the cutting tool 1A (main body 3). The rotation direction O2 is not limited to the direction shown in Fig. 1. For example, the cutting tool 1A may be configured inverted around the rotation axis O1 relative to the configuration shown in Fig. 1, in which case the rotation direction O2 will be reversed.

[0012] The cutting tool 1A of the first embodiment has a generally disk-like shape with a rotation axis O1 extending from the front end 3A to the rear end 3B. The length of the main body 3 in the direction along the rotation axis O1 is, for example, 50 mm to 100 mm. The outer diameter of the main body 3 in the direction perpendicular to the rotation axis O1 is, for example, 100 mm to 300 mm.

[0013] As a non-limiting example shown in FIG. 1 etc., the cutting tool 1A has a main body 3 and an insert 4. The main body 3 is a base portion of the cutting tool 1A and extends from a front end 3A to a rear end 3B along a rotation axis O1. The main body 3 also has a plurality of pockets 5 located on the front end 3A side. The pockets 5 may open on the outer peripheral surface of the main body 3 and on the end face on the front end 3A side. The pockets 5 have a seating surface 6 to which the insert 4 is attached. In the drawings, members marked with reference numerals 4A, 4B, and 4C correspond to the insert 4. Furthermore, portions marked with reference numerals 5A, 5B, and 5C correspond to the pocket 5. Portions marked with reference numerals 6A, 6B, and 6C correspond to the seating surface 6.

[0014] The insert 4 is located in the pocket 5 and attached to the main body 3. The insert 4 has a cutting edge 7 located on the tip 3A side. In a non-limiting example shown in FIG. 1 etc., the insert 4 may be attached to the main body 3 with a fastener 8 such as a screw. The insert 4 has a lower surface 9 facing rearward in the rotational direction O2, and the lower surface 9 is in contact with the seat surface 6 of the pocket 5. There are no particular limitations on the shapes of the seat surface 6 and the lower surface 9, but they may be flat. In the drawings, the portions marked with the reference numerals 7A, 7B, and 7C correspond to the cutting edge 7.

[0015] Here, Fig. 2 is a plan view of the cutting tool 1A shown in Fig. 1 as seen from the X1 direction, a side view of the insert 4 (first insert 4A), and a front view of the insert 4 (second insert 4B). Fig. 3 is a plan view of the cutting tool 1A shown in Fig. 1 as seen from the X2 direction, a side view of the insert 4 (second insert 4B), and a front view of the insert 4 (first insert 4A). Hereinafter, when an object such as the insert 4 cannot be seen when viewed from the front or side, the object may be evaluated when viewed from the front or side.

[0016] 1 to 3, the main body 3 has a first pocket 5A and a second pocket 5B. The first pocket 5A has a first seating surface 6A, and the second pocket 5B has a second seating surface 6B. The number of first pockets 5A and second pockets 5B is not limited to one each, and there may be more than one.

[0017] 4 is a plan view of the cutting tool 1A shown in FIG. 1 as viewed from the X3 direction, and is a view of the cutting tool 1A as viewed from the tip. In the non-limiting example shown in FIG. 4, the main body 3 has two first pockets 5A and two second pockets 5B. The main body 3 may have only the first pockets 5A and the second pockets 5B as the pockets 5, as in the non-limiting example shown in FIG. 4, or may have pockets 5 other than the first pockets 5A and the second pockets 5B, as in cutting tool 1B described later.

[0018] The cutting tool 1A has a first insert 4A and a second insert 4B. The number of each of the first insert 4A and the second insert 4B is not limited to one, and may be multiple. In a non-limiting example shown in FIG. 4, the number of first inserts 4A corresponds to the number of first pockets 5A, and the number of second inserts 4B corresponds to the number of second pockets 5B, respectively, so the cutting tool 1A has two first inserts 4A and two second inserts 4B. The cutting tool 1A may have only the first inserts 4A and the second inserts 4B as the inserts 4, as in the non-limiting example shown in FIG. 4, or may have inserts 4 other than the first inserts 4A and the second inserts 4B, as in cutting tool 1B.

[0019] The first insert 4A has a first cutting edge 7A located on the side of the tip 3A. The second insert 4B has a second cutting edge 7B located on the side of the tip 3A. The first cutting edge 7A and the second cutting edge 7B each have a leading edge 10 and a major cutting edge 12. In this embodiment, the first insert 4A and the second insert 4B are inserts 4 for C-chamfering, and have leading edge 10 and major cutting edge 12 as cutting edges 7 (first cutting edge 7A and second cutting edge 7B). In the drawings, the parts marked with the reference numerals 10A, 10B, and 10C correspond to the leading edge 10. The parts marked with the reference numerals 12A, 12B, and 12C correspond to the major cutting edge 12.

[0020] The tip cutting edge 10 is a cutting edge located on the tip 3A side of the insert 4 and extending in a direction generally perpendicular to the rotation axis O1. The main cutting edge 12 is a cutting edge that is mainly used during chamfering and extends at an angle relative to the rotation axis O1. There are no particular limitations on the shapes of the tip cutting edge 10 and the main cutting edge 12, but the tip cutting edge 10 and the main cutting edge 12 may each be curved or linear. In a non-limiting example shown in FIG. 4, the main cutting edge 12 is connected to the tip cutting edge 10.

[0021] When the cutting tool 1A is viewed from the front end, the cutting edges 7 may be arranged in the order of the tip edge 10 and the main cutting edge 12 from the rotation axis O1 side toward the outer periphery. When the insert 4 attached to the cutting tool 1A is viewed from the side, the cutting edges 7 may be arranged in the order of the tip edge 10 and the main cutting edge 12 from the front end 3A side toward the rear end 3B side.

[0022] When the inclination of the main cutting edge 12 with respect to an imaginary line L1 perpendicular to the rotation axis O1 when the insert 4 is viewed from the front is defined as α, the inclination of the main cutting edge 12 in the first insert 4A (cutting edge angle of the first insert 4A) is defined as α1, and the inclination of the main cutting edge 12 in the second insert 4B (cutting edge angle of the second insert 4B) is defined as α2, then in a non-limiting example shown in Figures 2 and 3, these cutting edge angles α1 and α2 are 45°. Note that the cutting edge angles α1 and α2 are not limited to specific values ​​and may be 10° to 60°.

[0023] As shown in Figures 5 to 8, the first cutting edge 7A has a first tip edge 10A and a first main cutting edge 12A, and the second cutting edge 7B has a second tip edge 10B and a second main cutting edge 12B. In the non-limiting example shown in Figures 5 and 7, the first main cutting edge 12A is in contact with the first tip edge 10A, and in the non-limiting example shown in Figures 6 and 8, the second main cutting edge 12B is in contact with the second tip edge 10B.

[0024] As a non-limiting example shown in Figures 5 and 6, when the axial rake AR of the first insert 4A is defined as the first axial rake AR1 and the axial rake AR of the second insert 4B is defined as the second axial rake AR2, the first axial rake AR1 is positive and the second axial rake AR2 is negative.

[0025] Here, the axial rake AR refers to the angle between the rotation axis O1 and the cutting edge 7 when the insert 4 attached to the cutting tool 1A is viewed from the side. Specifically, as shown in a non-limiting example in FIGS. 5 and 6, it refers to the angle between the rotation axis O1 and an imaginary line L2 passing through the main cutting edge 12. If the main cutting edge 12 is not straight, the imaginary line L2 may be a line passing through the end portion (leading edge portion 13) of the main cutting edge 12 located on the leading edge 3A side and the end portion (rear edge portion 14) located on the rear edge 3B side. For ease of explanation, in FIGS. 5, 6, and 10, the axial rake AR and the like are indicated by a line O10 parallel to the rotation axis O1 instead of the rotation axis O1. In the drawings, the portions marked with reference numerals 13A, 13B, and 13C correspond to the leading edge portion 13.

[0026] The magnitude of the first axial rake AR1 may be +5° to +20°, and the magnitude of the second axial rake AR2 may be -20° to -5°.

[0027] Generally, Poisson burrs are likely to occur near both ends of the chamfered surface, especially at the end where the cutting edge 7 was in contact with the workpiece just before it separated from it. For example, when chamfering using the 45° insert 4 of this embodiment, if the axial rake AR is positive as in the first insert 4A, the portion of the first cutting edge 7A (first major cutting edge 12A) that comes into contact with the chamfered surface just before it completely separates from it is the portion of the first cutting edge 7A closer to the rear end 3B. Therefore, burrs occur near the upper end of the chamfered surface. In contrast, if the axial rake AR is negative as in the second insert 4B, the portion of the second cutting edge 7B (second major cutting edge 12B) that comes into contact with the chamfered surface just before it completely separates from it is the portion of the second cutting edge 7B closer to the front end 3A. Therefore, burrs occur near the lower end of the chamfered surface.

[0028] When chamfering is performed using a cutting tool 1A that is composed of only inserts 4 with either a positive or negative axial rake AR, burrs tend to be generated unevenly near either the top or bottom of the chamfered surface.

[0029] However, since the cutting tool 1A in this embodiment has an insert 4 (first insert 4A) with a positive axial rake AR and an insert 4 (second insert 4B) with a negative axial rake AR, even if a burr occurs near the upper end of the chamfered surface when cutting with the first insert 4A, the burr near the upper end of the chamfered surface is easily removed by the second cutting edge 7B when cutting is subsequently performed with the second insert 4B.

[0030] Similarly, even after cutting with the second insert 4B, when cutting with the first insert 4A is performed, the generation of burrs can be suppressed. That is, even if burrs are generated near the bottom end of the chamfered surface during cutting with the second insert 4B, the burrs are easily removed by the first cutting edge 7A in the subsequent cutting with the first insert 4A.

[0031] In this way, by alternately performing cutting using the first insert 4A and cutting using the second insert 4B, burrs generated during cutting using one insert 4 are removed by cutting using the other insert 4, thereby suppressing the occurrence of Poisson burrs.

[0032] As described above, the cutting tool 1A in this embodiment can perform chamfering while suppressing the generation of burrs without requiring a cutting edge 7 with a special shape as in the prior art, i.e., without being restricted by the processing conditions due to the shape of the cutting edge 7 of the insert 4 used in the cutting processing.

[0033] Specifically, even when a repertoire of cutting tools with different outer diameters is prepared, the axial rakes AR of the first cutting edges 7A and second cutting edges 7B can be adjusted by adjusting the angles of the seating surfaces 6 (first seating surfaces 6A and second seating surfaces 6B) of the first pocket 5A and second pocket 5B of each cutting tool. Therefore, the first insert 4A and the second insert 4B can be reused in each cutting tool. Therefore, the cutting tool 1A is an insert-type cutting tool that suppresses burr generation.

[0034] The absolute value of the magnitude of the axial rake AR of the first insert 4A may be larger than the absolute value of the magnitude of the axial rake AR of the second insert 4B. Specifically, the difference between the two absolute values ​​may be 3° to 15°. Generally, when the axial rake AR is positive, the machining accuracy improves in proportion to the magnitude of the axial rake AR. Therefore, when the magnitude of the positive axial rake AR is relatively large, chamfering can be performed with high machining accuracy.

[0035] The first seating surface 6A may be inclined with respect to the rotation axis O1, and the second seating surface 6B may be inclined with respect to the rotation axis O1. Here, when the inclination angle θ of the first seating surface 6A with respect to the rotation axis O1 is defined as a first inclination angle θ1 and the inclination angle θ of the second seating surface 6B with respect to the rotation axis O1 is defined as a second inclination angle θ2, in the non-limiting example shown in FIGS. 5 and 6, the first inclination angle θ1 is positive and the second inclination angle θ2 is negative. The first insert 4A contacts the first seating surface 6A. The second insert 4B contacts the second seating surface 6B.

[0036] 5 and 6, the inclination angle θ refers to the angle between the rotation axis O1 and an imaginary straight line L3 of the seating surface 6 of the insert 4 when the insert 4 attached to the main body 3 is viewed from the side. If the entire seating surface 6 is not flat and does not have a linear shape when viewed from the side, the imaginary straight line L3 may be evaluated as an extension of the part of the lower surface 9 of the insert 4 that is in contact with the seating surface 6 when viewed from the side.

[0037] 5 and 6, when inserts 4 having cutting edges 7 with a common positional relationship with respect to the lower surface 9 (hereinafter referred to as common inserts 4) are used as the inserts 4 attached to the main body 3, the axial rake AR of each insert 4 depends on the inclination angle θ of the seating surface 6 to which each insert 4 is attached. Therefore, even when the common inserts 4 mentioned above are used as the first insert 4A and the second insert 4B, the cutting tool 1A can be provided with inserts 4 having both positive and negative axial rakes AR, thereby reducing the required repertoire of inserts.

[0038] Here, a common insert 4 does not necessarily mean that the inserts 4 being compared have exactly the same shape. For example, when the insert 4 attached to the seat surface 6 is viewed from the side, it may be evaluated as a common insert 4 when the angle formed by the imaginary straight line L2 of the main cutting edge 12 and the imaginary straight line L3 of the seat surface 6 is the same.

[0039] The absolute value of the magnitude of the first tilt angle θ1 may be greater than the absolute value of the magnitude of the second tilt angle θ2. Specifically, the difference between the two absolute values ​​may be 3° to 20°. The magnitude of the first tilt angle θ1 may be +5° to +30°. The magnitude of the second tilt angle θ2 may be -30° to -5°.

[0040] When the radial rake RR of the first insert 4A is designated as the first radial rake RR1 and the radial rake RR of the second insert 4B is designated as the second radial rake RR2, the first radial rake RR1 may be smaller than the second radial rake RR2. In this case, it is possible to suppress the variation in cutting resistance caused by the difference between the axial rake AR of the first insert 4A and the axial rake AR of the second insert 4B.

[0041] Here, the radial rake RR refers to the angle formed by the cutting edge 7 and an imaginary line L4 passing through the rotation axis O1 and the outer peripheral end of the cutting edge 7 when the insert 4 attached to the cutting tool 1A is viewed from the tip. Specifically, as shown in a non-limiting example in FIG. 7 etc., the radial rake RR refers to the angle formed by the imaginary line L4 passing through the rotation axis O1 and the outer peripheral end (outer end 15) of the main cutting edge 12 and an imaginary line L5 of the main cutting edge 12. Note that if the main cutting edge 12 is not a straight line, a line passing through the end (inner end 16) of the main cutting edge 12 on the rotation axis O1 side and the outer end 15 may be evaluated as the imaginary line L5. Note that the first radial rake RR1 may be −30° to +15°, and the second radial rake RR2 may be −15° to +30°. Furthermore, the first radial rake RR1 may be the same as the second radial rake RR2.

[0042] The end of the main cutting edge 12 located on the tip 3A side is defined as the tip 13. Here, if the tip 13 of the first cutting edge 7A is defined as the first tip 13A and the tip 13 of the second cutting edge 7B is defined as the second tip 13B, in a non-limiting example shown in Fig. 2, the first tip 13A is the tip 13 of the first main cutting edge 12A, and the second tip 13B is the tip 13 of the second main cutting edge 12B. Note that when the tip edge 10 and the main cutting edge 12 contact each other, as in a non-limiting example shown in Fig. 5, the portion where the tip edge 10 and the main cutting edge 12 intersect may be defined as the tip 13.

[0043] In the direction along the rotation axis O1, the first tip portion 13A may be located at the same position as the second tip portion 13B. Specifically, as shown in a non-limiting example in FIG. 3, when the cutting tool 1A is viewed from the side, the first tip portion 13A and the second tip portion 13B may be located on a line perpendicular to the rotation axis O1. In such a case, the heights of the cutting edges 7 are uniform, making it less likely that steps will occur on the machined surface. Note that the term "same position" may include a position within a range of -5 to +5% of the size of the insert 4 in the direction along the rotation axis O1.

[0044] The first insert 4A may be adjacent to the second insert 4B in the rotation direction O2 of the rotation axis O1. In this case, the workpiece can be cut by the insert 4 with a negative axial rake AR immediately after cutting by the insert 4 with a positive axial rake AR, which further reduces the likelihood of burrs being generated.

[0045] Here, adjacent refers to a case where, when the cutting tool 1A is viewed from the front end, the inserts 4 closest to the first insert 4A in the front-rear direction of the rotational direction O2 are both the second insert 4B, as in the non-limiting example shown in Figure 4. Note that the above relationship also holds when there is one first insert 4A and one second insert 4B. For example, there may be a case where the main body 3 has two pockets 5, each consisting of one first pocket 5A and one second pocket 5B.

[0046] The cutting tool 1B according to the second embodiment includes a main body 3 and an insert 4. With regard to the cutting tool 1B according to the second embodiment, the description of the first embodiment is used to refer to the parts having the same configuration as the cutting tool 1A according to the first embodiment, and detailed description thereof will be omitted. The description of the first embodiment is also used to refer to the definitions of angles and virtual straight lines.

[0047] In the cutting tool 1B of the second embodiment, the main body 3 further has a third pocket 5C located on the side of the tip 3A in addition to the first pocket 5A and the second pocket 5B. The third pocket 5C has a third seating surface 6C.

[0048] Furthermore, the cutting tool 1B has a third insert 4C attached to the third seating surface 6C in addition to the first insert 4A and the second insert 4B. Here, FIG. 9 is a side view showing the cutting tool 1B according to the second embodiment, a side view of the third insert 4C, and a front view of the first insert 4A and the second insert 4B. In the non-limiting example shown in FIG. 9, the cutting tool 1B has one first insert 4A, one second insert 4B, and two third inserts 4C. The third insert 4C has a third cutting edge 7C, and the third cutting edge 7C has a third tip cutting edge 10C and a third major cutting edge 12C. The inclination of the major cutting edge 12 of the third insert 4C (cutting angle of the third insert 4C) is not limited to a specific value and may be 10° to 60°.

[0049] As a non-limiting example shown in Figure 10, when the axial rake AR of the third insert 4C is defined as a third axial rake AR3, the third axial rake AR3 may be smaller than the first axial rake AR1 or larger than the second axial rake AR2. In this case, burrs remaining on the machined surface can be removed by the third cutting edge 7C. The magnitude of the third axial rake AR3 may be between -3° and +3°.

[0050] In the rotational direction O2 of the rotation axis O1, the third insert 4C is adjacent to the first insert 4A and the second insert 4B. Specifically, this refers to a case where the inserts 4 located closest to the third insert 4C in the front-rear direction of the rotational direction O2 are the first insert 4A and the second insert 4B. However, in this case, multiple third inserts 4C may be located between the first insert 4A and the second insert 4B.

[0051] In such a case, after cutting with the first insert 4A, which has a positive axial rake AR, the burrs left on the machined surface are scraped away by the cutting edge 7 of the third insert 4C, and then the workpiece can be cut continuously with the second insert 4B, which has a negative axial rake AR, making it even less likely that burrs will be produced.

[0052] 11 is an enlarged view of region Y5 shown in FIG. 9 as viewed from the X4 direction, and is an enlarged view of the cutting tool 1B as viewed from the front end. As a non-limiting example shown in FIG. 11, when the radial rake RR of the third insert 4C is defined as the third radial rake RR3, the third radial rake RR3 may be smaller than the first radial rake RR1 or larger than the second radial rake RR2. In this case, it is possible to suppress variations in cutting resistance due to differences in the axial rakes AR of the first insert 4A, the second insert 4B, and the third insert 4C. The magnitude of the third radial rake RR3 may be −10° to +10°.

[0053] If the tip 13 of the third cutting edge 7C is defined as the third tip 13C, in a non-limiting example shown in FIG. 9, the third tip 13C is the tip 13 of the third major cutting edge 12C. In the direction along the rotation axis O1, the third tip 13C may be located at the same position as the first tip 13A and the second tip 13B. Specifically, as in the non-limiting example shown in FIG. 9, when the cutting tool 1B is viewed from the side, the first tip 13A, the second tip 13B, and the third tip 13C may be located on a line perpendicular to the rotation axis O1. In such a case, the cutting edges 7 are all at the same height, which reduces the likelihood of steps occurring on the machined surface.

[0054] When the cutting tool 1A and the cutting tool 1B have a plurality of first inserts 4A, the first inserts 4A may be arranged rotationally symmetrically with respect to the cutting tool 1A and the cutting tool 1B about the rotation axis O1. For example, as shown in a non-limiting example in FIG. 4, when the cutting tool 1A is viewed from the front end, if the cutting tool 1A has two first inserts 4A, the first inserts 4A are arranged to have 180° rotational symmetry. In other words, if there are N first pockets 5A, the first pockets 5A may be arranged to have (360° / N) rotational symmetry. The same applies to the second insert 4B and the third insert 4C.

[0055] In the above case, the cutting load is likely to be applied uniformly around the rotation axis O1 during cutting, which reduces the variation in the cutting load applied to each insert, thereby reducing, for example, the variation in wear of each insert.

[0056] When the cutting tool 1A and the cutting tool 1B each have a plurality of first inserts 4A and a plurality of second inserts 4B, the first inserts 4A may be disposed at equal intervals around the rotation axis O1 relative to the second inserts 4B. For example, as shown in a non-limiting example in FIG. 4, when the cutting tool 1A is viewed from the front end, the first inserts 4A are disposed at 90° intervals around the rotation axis O1 relative to the two second inserts 4B. This also applies when the first insert 4A or the second insert 4B is replaced with a third insert 4C.

[0057] Furthermore, in the embodiments of the present disclosure, there are no particular limitations on the number of first inserts 4A, second inserts 4B, and third inserts 4C, and for example, the number of first inserts 4A may be greater or less than the number of second inserts 4B.

[0058] Examples of materials for the insert 4 include cemented carbide and cermet. Examples of cemented carbide compositions include WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co. WC-Co is produced by adding cobalt (Co) powder to tungsten carbide (WC) and sintering the mixture. WC-TiC-Co is produced by adding titanium carbide (TiC) to WC-Co. WC-TiC-TaC-Co is produced by adding tantalum carbide (TaC) to WC-TiC-Co.

[0059] Cermets are sintered composite materials in which a ceramic component is combined with a metal. Specifically, cermets include those whose main component is a titanium compound such as titanium carbide (TiC) or titanium nitride (TiN).

[0060] The surface of the insert 4 may be coated with a coating by chemical vapor deposition (CVD) or physical vapor deposition (PVD), and the coating may have a composition such as titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and alumina (Al2O3).

[0061] The main body 3 can be made of steel, cast iron, aluminum alloy, or the like.

[0062] <Method for manufacturing machined products> Next, a method for manufacturing a machined product according to an unrestricted embodiment of the present disclosure will be described in detail using the cutting tool 1A according to the unrestricted first embodiment described above as an example. The description will be made below with reference to Figures 12 to 14. Note that Figures 12 to 14 illustrate the steps of cutting a workpiece 102 as an unrestricted example of a method for manufacturing a machined product 101.

[0063] A method for manufacturing the machined product 101 according to a non-limiting embodiment of the present disclosure may include the following steps (1) to (3).

[0064] (1) The cutting tool 1A may be rotated about the rotation axis O1 in a rotation direction O2, and moved toward the workpiece 102 in a feed direction S1 (see FIG. 12).

[0065] This step can be performed, for example, by fixing the workpiece 102 on a table of a machine tool to which the cutting tool 1A is attached, and bringing the cutting tool 1A closer to the workpiece 102 while rotating. Note that in this step, it is sufficient that the workpiece 102 and the cutting tool 1A are relatively close to each other, and the workpiece 102 may be brought closer to the cutting tool 1A.

[0066] (2) The cutting tool 1A may be brought even closer to the workpiece 102, so that the rotating cutting tool 1A comes into contact with a desired position on the surface of the workpiece 102, thereby cutting the workpiece 102 (see FIG. 13).

[0067] In this step, the cutting blade 7 may be brought into contact with a desired position on the surface of the workpiece 102 .

[0068] (3) The cutting tool 1A may be moved away from the workpiece 102 in the S1 direction (see FIG. 14).

[0069] In this step, similarly to the above step (1), the cutting tool 1A may be relatively separated from the workpiece 102, for example, the workpiece 102 may be separated from the cutting tool 1A.

[0070] By going through the above steps, it is possible to achieve excellent processability.

[0071] In addition, when performing cutting processing of the workpiece 102 as described above multiple times, for example, when performing multiple cutting processes on one workpiece 102, the process of contacting the cutting tool 1A with different locations on the workpiece 102 while keeping the cutting tool 1A rotated may be repeated.

[0072] Examples of materials for the workpiece 102 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0073] In one embodiment, [1] the cutting tool includes a body portion extending from the tip end to the rear end along a rotation axis and having a first pocket and a second pocket each located on the tip side, a first insert located in the first pocket and having a first cutting edge, and a second insert located in the second pocket and having a second cutting edge, and the axial rake of the first insert may be positive and the axial rake of the second insert may be negative.

[0074] [2] In the cutting tool of the above [1], the absolute value of the size of the axial rake of the first insert may be larger than the absolute value of the size of the axial rake of the second insert.

[0075] [3] In the cutting tool of [1] or [2] above, the first pocket may have a first seating surface inclined at a positive angle with respect to the rotation axis, the second pocket may have a second seating surface inclined at a negative angle with respect to the rotation axis, the first insert may be in contact with the first seating surface, and the second insert may be in contact with the second seating surface.

[0076] [4] In the cutting tool according to any one of the above [1] to [3], the radial rake of the first insert may be smaller than the radial rake of the second insert.

[0077] [5] In any of the cutting tools [1] to [4] above, the first cutting edge may have a first tip portion located at an end closer to the tip, and the second cutting edge may have a second tip portion located at an end closer to the tip, and the first tip portion may be located at the same position as the second tip portion in a direction along the rotation axis.

[0078] [6] In the cutting tool according to any one of the above [1] to [5], the first insert may be adjacent to the second insert in the rotation direction of the rotation shaft.

[0079] [7] In any of the cutting tools [1] to [6] above, the main body portion may further have a third pocket located on the tip side, and a third insert located in the third pocket and having a third cutting edge, the third insert may be adjacent to the first insert and the second insert in the rotational direction of the rotation shaft, and the axial rake of the third insert may be smaller than the axial rake of the first insert and larger than the axial rake of the second insert.

[0080] [8] The method may include the steps of rotating any one of the cutting tools [1] to [7] above, bringing the cutting tool into contact with a workpiece, and removing the cutting tool from the workpiece. [Explanation of symbols]

[0081] 1A~1B...Cutting tools 3. Main body 3A...Tip 3B...Rear end 4. Insert 4A···First insert 4B...Second insert 4C···Third insert 5 pockets 5A···First pocket 5B...Second pocket 5C Third pocket 6. Seat 6A···1st seat 6B...Second seat 6C...Third seat 7. Cutting edge 7A...1st cutting edge 7B...Second cutting edge 7C...Third cutting edge 8... Fixture 9...Bottom surface 10 Tip blade 10A···First tip blade 10B...Second tip cutting edge 10C...Third tip blade 12 Main cutting edge 12A...1st main cutting edge 12B...2nd main cutting edge 12C...Third main cutting edge 13...Tip 13A...1st tip 13B...Second tip 13C...Third tip 14...Rear end 15...outer end 16...inner end 101...Cutting workpiece 102...Work material O1 Rotation axis O2 Rotation direction O10: A straight line parallel to the axis of rotation L1~L5: Virtual straight lines S1 Feed direction α: Inclination of main cutting edge α1: Inclination of the first main cutting edge (cutting angle) α2: Inclination of the second main cutting edge (cutting angle) AR···Axial Rake AR1: First axial rake AR2: Second axial rake AR3: Third Axial Rake RR···Radial rake RR1: First radial rake RR2: Second radial rake RR3: Third radial rake θ...Inclination angle θ1...1st inclination angle θ2...Second tilt angle θ3...Third tilt angle

Claims

1. a main body portion extending from a front end to a rear end along a rotation axis and having a first pocket and a second pocket each located on the front end side; a first insert located in the first pocket and having a first cutting edge; a second insert located in the second pocket and having a second cutting edge, The axial rake of the first insert is positive; the second insert has a negative axial rake; the absolute value of the axial rake of the first insert is greater than the absolute value of the axial rake of the second insert; the first cutting edge has a first tip portion located at an end on the tip side, the second cutting edge has a second tip portion located at an end on the tip side, A cutting tool, wherein the first tip portion is at the same position as the second tip portion in a direction along the rotation axis.

2. the first pocket has a first seating surface inclined at a positive angle with respect to the rotation axis; the second pocket has a second bearing surface inclined at a negative angle relative to the rotation axis; the first insert contacts the first seating surface; The cutting tool according to claim 1 , wherein the second insert abuts the second seating surface.

3. The cutting tool according to claim 1 or 2, wherein the radial rake of the first insert is smaller than the radial rake of the second insert.

4. The cutting tool according to claim 1 or 2, wherein the first insert is adjacent to the second insert in the rotation direction of the rotation shaft.

5. The main body further includes a third pocket located on the tip side, a third insert located in the third pocket and having a third cutting edge; the third insert is adjacent to the first insert and the second insert in the rotation direction of the rotation shaft, The cutting tool according to claim 1 or 2, wherein the axial rake of the third insert is smaller than the axial rake of the first insert and larger than the axial rake of the second insert.

6. a step of rotating the cutting tool according to claim 1 or 2; contacting the cutting tool with a workpiece; and removing the cutting tool from the workpiece.

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