Cutting tool and method for manufacturing machined product

Abstract

To obtain a cutting tool which enables reduction of risks of damage in an insert etc.SOLUTION: A cutting tool based on one embodiment of the disclosure has a holder, an insert, and a fixture. The insert has a front surface, a rear surface, an outer surface, an inner surface, a through hole, and an outer peripheral blade. The outer peripheral blade has: a top part located at a forefront portion in a rotation direction; a first outer peripheral blade which extends from the top part to a tip and whose axial rake angle is a negative value; and a second outer peripheral blade which extends from the top part to a rear end and whose axial rake angle is a positive value. A pocket has a seating surface and a fixing hole. At least a part of the seating surface is located at the tip side relative to the top part. The second outer peripheral blade is longer than the first outer peripheral blade.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a cutting tool and a method for manufacturing a machined product. [Background technology]

[0002] Known cutting tools include, for example, the cutting tool described in Patent Document 1. Generally, when an insert is attached to a holder using a fastener such as a screw, a tool in which the fastener is inserted along the circumferential direction of the rotation axis of the holder is called a flat-type tool, whereas a tool in which the fastener is inserted along the radial direction of the holder, such as the cutting tool described in Patent Document 1, is called a vertical-type tool.

[0003] Compared to flat-type cutting tools, vertical-type cutting tools allow the radial width of the holder pocket in which the insert is attached to be smaller, which ensures the core thickness of the holder and increases the rigidity of the holder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-136802 Summary of the Invention [Problem to be solved by the invention]

[0005] In vertically mounted cutting tools, there is a need to reduce the risk of breakage of inserts and other parts. [Means for solving the problem]

[0006] A cutting tool according to one embodiment of the present disclosure is a cutting tool extending from a front end to a rear end along a rotation axis, and includes a holder having a pocket located on the front end side, an insert located in the pocket, and a fastener for fixing the insert to the holder. The insert has a front side located forward in the rotation direction of the rotation axis, a rear side located rearward in the rotation direction, an outer side located on the outer periphery and connected to the front and rear sides, an inner side located inner periphery and connected to the front and rear sides, a through hole penetrating the outer side and inner side and into which the fastener is inserted, and a cutting edge located on the outer edge of the front side. The cutting edge has a peripheral cutting edge located at the intersection of the front side and the outer side. The peripheral cutting edge has an apex located farthest forward in the rotation direction, a first peripheral cutting edge extending from the apex toward the front end and having a negative axial rake angle, and a second peripheral cutting edge extending from the apex toward the rear end and having a positive axial rake angle. The pocket has a seat that abuts against the rear side surface and a fixing hole that faces the outer periphery and into which the fixing device is inserted. At least a portion of the seat is located closer to the tip than the apex. The second peripheral cutting edge is longer than the first peripheral cutting edge. [Effects of the Invention]

[0007] The cutting tool described above can reduce the risk of breakage of the insert or the like. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a cutting tool according to an embodiment; [Figure 2] FIG. 2 is a plan view of the cutting tool shown in FIG. 1 as viewed from the A1 direction. [Figure 3] FIG. 3 is an enlarged view of an area B1 shown in FIG. [Figure 4] FIG. 4 is an enlarged view showing a holder in the cutting tool shown in FIG. 3. [Figure 5] FIG. 4 is an enlarged view of an area B2 shown in FIG. [Figure 6] FIG. 4 is an enlarged view of an area B3 shown in FIG. [Figure 7] 1A and 1B are plan views of an insert according to one embodiment, as viewed from the rear side and the outer side, respectively. [Figure 8] FIG. 1 is a plan view of an insert according to one embodiment, viewed from the front side. [Figure 9] FIG. 2 is a plan view of an insert according to one embodiment, viewed from the inner surface side. [Figure 10] FIG. 2 is a schematic explanatory view showing one step of a method for manufacturing a machined product according to one embodiment. [Figure 11] FIG. 2 is a schematic explanatory view showing one step of a method for manufacturing a machined product according to one embodiment. [Figure 12] FIG. 2 is a schematic explanatory view showing one step of a method for manufacturing a machined product according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The cutting tools shown below will be described in detail with reference to the 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 any components not shown in the drawings referred to. 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] As shown in Fig. 1, the cutting tool 1 according to this embodiment is a so-called rotary tool that rotates around a rotation axis O1 in a rotation direction O2. Examples of rotary tools include an end mill and a milling cutter. The example rotary tool shown in Fig. 1 is an end mill. Note that this embodiment is a non-limiting aspect of the present invention.

[0011] The rotation axis O1 is an axis about which the cutting tool 1 rotates, and is not a tangible part of the cutting tool 1 (holder 3). The rotation direction O2 is not limited to the direction shown in Fig. 1. For example, the cutting tool 1 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 1 has a generally cylindrical shape with a rotation axis O1 extending from a front end 3A to a rear end 3B. The outer diameter of the cutting tool 1 in a direction perpendicular to the rotation axis O1 is, for example, 16 mm to 50 mm.

[0013] As shown in Fig. 1, cutting tool 1A has a holder 3, an insert 5, and a fixture 7. In an example shown in Fig. 2, a leading end 3A of cutting tool 1 is located in the insert, and a trailing end 3B of cutting tool 1 is located in holder 3. Here, Fig. 2 is a plan view of cutting tool 1 shown in Fig. 1 as viewed from the A1 direction.

[0014] The holder 3 is the base of the cutting tool 1 and has a plurality of pockets 9 located on the tip 3A side. The insert 5 is located in the pocket 9 and attached to the holder 3 using a fastener 7. There is no particular limitation on the type of fastener 7, but in this embodiment, the fastener 7 is a screw.

[0015] 3 is an enlarged view of region B1 shown in Fig. 2, and Fig. 4 is an enlarged view of region B1 shown in Fig. 2, showing the cutting tool 1 without the insert 5 and the fixture 7, i.e., the holder 3. Furthermore, Fig. 5 is an enlarged view of region B2 shown in Fig. 3, and Fig. 6 is an enlarged view of region B3 shown in Fig. 3.

[0016] In this embodiment, the insert 5 is a front end located in front of the rotation direction O2 of the rotation axis O1. The front side surface 11 has a side surface 11 and a rear side surface 13 located rearward in the rotation direction O2. The front side surface 11 may have a polygonal shape when viewed from the front. Similarly, the rear side surface 13 may have a polygonal shape when viewed from the front. For example, the front side surface 11 and the rear side surface 13 may each have a rectangular shape. The front side surface 11 has a front flat surface 11A that is a planar shape facing forward in the rotation direction O2, and the rear side surface 13 has a rear flat surface 13A that is a planar shape facing rearward in the rotation direction O2. The front flat surface 11A is located at the center of the front side surface 11, and the rear flat surface 13A is located at the center of the rear side surface 13. For convenience of explanation, the rear side surface 13 is shown in perspective by a dotted line in Figures 3 and 6.

[0017] Furthermore, in this embodiment, the insert 5 has an outer surface 15 located on the outer circumferential side and connected to the front surface 11 and the rear surface 13, and an inner surface 17 located on the inner circumferential side and connected to the front surface 11 and the rear surface 13. Here, the outer circumferential side refers to the side away from the rotation axis O1, and the inner circumferential side refers to the side closer to the rotation axis O1.

[0018] In addition, Figure 7 is a plan view of the insert 5 viewed from the rear side 13 side and the insert 5 viewed from the outer side 15 side, Figure 8 is a plan view of the insert 5 viewed from the front side 11 side, and Figure 9 is a plan view of the insert 5 viewed from the inner side 17 side.

[0019] 7, the insert 5 is located on the side of the front end 3A and has a front end surface 19 facing the front end 3A. The insert 5 is also located on the side of the rear end 3B and has a rear end surface 21 facing the rear end 3B. The front end surface 19 and the rear end surface 21 are connected to the front side surface 11, the rear side surface 13, the inner side surface 17, and the outer side surface 15, respectively.

[0020] In the insert 5 of this embodiment, the front side surface 11 and the rear side surface 13 have the same shape and the same configuration. The outer side surface 15 and the inner side surface 17 also have the same shape and the same configuration. The leading end surface 19 and the rear end surface 21 also have the same shape and the same configuration. The front side surface 11, the rear side surface 13, the inner side surface 17, the outer side surface 15, the leading end surface 19, and the rear end surface 21 may have flat portions or may have irregularities.

[0021] The insert 5 has a through hole 23 that penetrates from the outer surface 15 to the inner surface 17 and into which the fastener 7 is inserted. In this embodiment, the outer surface 15 faces the outer periphery side and the inner surface 17 faces the inner periphery side, and therefore the through hole 23 and the central axis N1 of the through hole 23 extend from the inner periphery side to the outer periphery side, i.e., along the radial direction of the rotation axis O1.

[0022] The insert 5 has a cutting edge 24 located on the outer edge of the front side surface 11. The cutting edge 24 is used when cutting a workpiece. The cutting edge 24 may be located on the entire outer edge of the front side surface 11, or may be located on only a portion of the outer edge of the front side surface 11. In this embodiment, the cutting edge 24 has a peripheral cutting edge 25 located at the intersection of the front side surface 11 and the outer side surface 15. Since the front side surface 11 is located forward in the rotation direction O2, the front side surface 11 may function as a rake face and the outer side surface 15 may function as a relief face.

[0023] The peripheral cutting edge 25 has a crest 27. The crest 27 is located at the most forward position in the rotational direction O2 of the peripheral cutting edge 25. Here, "located most forward in the rotational direction O2" may be interpreted as being located most forward in the rotational direction O2 among the portions of the peripheral cutting edge 25 that are located closer to the tip 3A than the central axis N2 of the fixture 7. In the example shown in FIG. 3, the crest 27 is located most forward in the rotational direction O2 when the insert 5 is attached to the holder 3. The fixture 7 and the central axis N2 of the fixture 7 extend along the through hole 23.

[0024] In addition, when there are a plurality of portions positioned furthest forward in the rotation direction O2, the portion positioned furthest to the tip 3A side may be defined as the apex 27. Although the apex 27 is shown as a point, the apex 27 may be, for example, a line extending perpendicular to the rotation direction O2.

[0025] The peripheral cutting edge 25 also has a first peripheral cutting edge 29 and a second peripheral cutting edge 31. The first peripheral cutting edge 29 extends from the apex 27 toward the front end 3A. The second peripheral cutting edge 31 extends from the apex 27 toward the rear end 3B.

[0026] In the insert 5 shown in this embodiment, the first peripheral cutting edge 29 has a first straight edge 29A and a first curved edge 29B. The second peripheral cutting edge 31 has a second straight edge 31A and a second curved edge 31B.

[0027] The first curved blade 29B extends from the apex 27 toward the tip 3A. The first straight blade 29A extends from the first curved blade 29B toward the tip 3A. The second curved blade 31B extends from the apex 27 toward the rear end 3B. The second straight blade 31A extends from the second curved blade 31B toward the rear end 3B. In the insert 5 of this embodiment, the first curved blade 29B and the second curved blade 31B have very small lengths, so they are shown enlarged in FIG. 5.

[0028] In the example shown in Figure 5, the first straight blade 29A and the second straight blade 31A have a straight shape when viewed from the side, and the first curved blade 29B and the second curved blade 31B have a convex curved shape when viewed from the side. Here, "side view" refers to the state when the insert 5 is viewed from the direction of the central axis N2 of the fixture 7. The "straight shape" also includes a shape that is linear in design but slightly curved due to unavoidable manufacturing processes. The radius of curvature of the first curved blade 29B and the radius of curvature of the second curved blade 31B may be constant and the same.

[0029] In the example shown in Figure 5, the axial rake angle θ1 of the first peripheral cutting edge 29 is a negative value, and the axial rake angle θ2 of the second peripheral cutting edge 31 is a positive value. Here, the axial rake angle refers to the angle between the rotation axis O1 and the peripheral cutting edge 25 when the insert 5 attached to the cutting tool 1 is viewed from the side. Specifically, it refers to the angle between an imaginary extension line T1 passing through the rotation axis O1 and the first peripheral cutting edge 29, and an imaginary extension line T2 passing through the rotation axis O1 and the second peripheral cutting edge 31. In Figure 5, for convenience of explanation, the axial rake angle is indicated using a straight line O10 parallel to the rotation axis O1 instead of the rotation axis O1.

[0030] In addition, when the first peripheral cutting edge 29 and the second peripheral cutting edge 31 have the first curved edge 29B and the second curved edge 31B, respectively, the straight line extending from the first straight edge 29A and the straight line extending from the second straight edge 31A may be evaluated as the imaginary extension line T1 and the imaginary extension line T2, respectively. In addition, in the cutting tool 1 shown in this embodiment, the axial rake angle at the apex 27 is 0°.

[0031] The pocket 9 has a seat 35 that abuts against the rear side surface 13. The seat 35 faces forward in the rotation direction O2. The seat 35 may have a flat portion 35A or may have an uneven surface. The flat portion 35A is located in the center of the seat 35. For ease of explanation, the flat portion 35A is shown in perspective by dotted lines in Figures 3 and 6.

[0032] In the cutting tool 1 shown in this embodiment, a portion of the rear side surface 13 that is located closer to the tip end 3A than the rear flat surface 13A also abuts against the bearing surface 35. In this way, the bearing surface 35 may have a shape corresponding to the rear side surface 13 so that the surface area that abuts against the rear side surface 13 is large.

[0033] The pocket 9 also has a restraining surface 37 that faces the inner surface 17. The restraining surface 37 abuts against the inner surface 17 and faces the outer periphery. The restraining surface 37 has a flat shape. The portion of the groove 31 that contacts the restraining surface 37 has a flat shape and faces the inner periphery.

[0034] The restraint surface 37 faces the outer periphery and has a fixing hole 39 into which the fixing device 7 is inserted. In the cutting tool 1 shown in this embodiment, the fixing device 7 is a screw, and therefore the fixing device 7 passes through the through hole 23, is inserted into the fixing hole 39, and is tightened to fix the insert 5 to the holder 3. In the cutting tool 1 shown in this embodiment, the fixing hole 39 extends from the inner periphery to the outer periphery, i.e., in the radial direction of the rotation axis O1.

[0035] In order to firmly abut the rear side surface 13 against the seat surface 35, for example, when the rear side surface 13 is abutted against the seat surface 35 but the fixing device 7 is not inserted into the fixing hole 39, the central axis N3 of the fixing hole 39 may be eccentric rearward in the rotational direction O2 relative to the central axis N1 of the through hole 23.

[0036] In the cutting tool 1 shown in this embodiment, at least a part of the portion where the rear side surface 13 and the seating surface 35 abut is located closer to the tip 3A than the apex 27. Specifically, in the example shown in Figures 3 and 5, a first abutment point P1, which is located closest to the tip 3A among the portions where the rear side surface 13 and the seating surface 35 abut, is located closer to the tip 3A than a straight line S2 that passes through the apex 27 and is perpendicular to the rotation axis O1.

[0037] In addition, in the cutting tool 1 shown in this embodiment, the second peripheral cutting edge 31 is longer than the first peripheral cutting edge 29. Specifically, in the example shown in Fig. 7, the length L1 of the first peripheral cutting edge 29 and the length L2 of the second peripheral cutting edge 31 have a magnitude relationship of L2 > L1.

[0038] Generally, during cutting, cutting resistance is applied in a direction perpendicular to the cutting edge, with the force applied in the direction opposite to the rotation direction O2 being called the principal force and the force applied in the direction of the rotation axis O1 being called the thrust force. Furthermore, a cutting edge with a negative axial rake angle is subjected to thrust force toward the rear end 3B, while a cutting edge with a positive axial rake angle is subjected to thrust force toward the front end 3A.

[0039] Therefore, since a thrust force is less likely to occur on a cutting edge with an axial rake angle of 0°, the principal force is less likely to be dispersed in the direction extending toward the rotation axis O1, and a larger principal force is more likely to be applied to the cutting edge than to a cutting edge with a positive or negative axial rake angle.

[0040] Furthermore, when cutting is performed using only cutting edges with a negative axial rake angle, the cutting edges tend to deviate toward the rear end 3B, and when cutting is performed using only cutting edges with a positive axial rake angle, the cutting edges tend to deviate toward the front end 3A. In either case, the machining accuracy is likely to decrease.

[0041] In the cutting tool 1 shown in this embodiment, the seat surface 35 is located on the rear side of the top 27 in the rotation direction O2, so that the large principal force acting on the top 27 can be absorbed by the seat surface 35, thereby reducing the risk of damage to the insert 5.

[0042] In addition, the first peripheral cutting edge 29 has a negative axial rake angle on the side of the leading edge 3A that first comes into contact with the workpiece, reducing the risk of chipping of the cutting edge. Furthermore, by locating the second peripheral cutting edge 31 closer to the rear end 3B than the first peripheral cutting edge 29, the thrust force acting on the first peripheral cutting edge 29 toward the rear end 3B is offset by the thrust force acting on the second peripheral cutting edge 31 toward the leading edge 3A, thereby suppressing the occurrence of misalignment of the cutting edge during cutting.

[0043] In addition, in the case of the vertically placed cutting tool 1, when the bearing surface 35 is located only on the rear end 3B side from the top 27, when a large principal force is applied to the top 27, the bearing surface 35 and the rear side surface 13 However, in the cutting tool 1 shown in this embodiment, the abutting portion is located on the side of the apex 27 toward the tip 3A, so that a large load is less likely to be applied to the fixture 7 in the rotational direction O2. As a result, the risk of damage to the fixture 7 and the insert 5 can be reduced.

[0044] At least a portion of the portion where the rear side surface 13 and the flat portion 35A contact each other may be located closer to the tip 3A than the apex 27. Specifically, in the example shown in Figures 3 and 6, the second contact point P2, which is located closest to the tip 3A among the portions where the rear side surface 13 and the flat portion 35A contact each other, is located closer to the tip 3A than a straight line S2 that passes through the apex 27 and is perpendicular to the rotation axis O1. In such a case, the large principal component of force acting on the apex 27 can be stably received by the flat portion 35A facing forward in the rotation direction O2.

[0045] Here, as an example shown in Figure 7, when the length from the center axis N1 of the through hole 23 to the apex 27 in the direction extending from the tip face 19 to the rear end face 21 is L3 and the length from the apex 27 to the end Q1 on the tip 3A side of the flat portion 35A is L4, from the viewpoint of enabling the second peripheral cutting edge 31 to contact the workpiece, it is desirable that L3 / L4 > 1, and from the viewpoint of reducing the risk of a large load being applied to the fixing device 7 in the rotational direction O2, it is desirable that L3 / L4 < 4.

[0046] Furthermore, when the peripheral cutting edge 25 has a first curved edge 29B and a second curved edge 31B, the apex 27 is rounded, making it less likely to chip during cutting. The first curved edge 29B may be longer than the second curved edge 31B. Specifically, in the example shown in Figure 5, the length L5 of the first curved edge 29B and the length L6 of the second curved edge 31B satisfy the relationship L5 > L6.

[0047] Generally, the cutting edge 24 located closer to the workpiece, i.e., the tip 3A side, is more likely to be subjected to a larger cutting load than the cutting edge 24 located farther from the workpiece, i.e., the rear end 3B side. Therefore, if the first curved edge 29B is relatively long, it becomes easier to distribute the cutting load applied near the apex 27, making it less likely that the apex 27 will chip.

[0048] The front side surface 11 has a first corner 41 located on the tip 3A side and on the outer periphery side. As described above, the front side surface 11 may be polygonal, or may be rectangular having four corners and four sides as shown in the figure. In this case, the corner of the four corners located on the tip 3A side and on the outer periphery side corresponds to the first corner 41.

[0049] The cutting edge 24 also has a first corner cutting edge 43 located at the first corner 41. The first corner cutting edge 43 is connected to the first peripheral cutting edge 29. More specifically, the first corner cutting edge 43 is connected to the first straight cutting edge 29A.

[0050] In the cutting tool 1 according to the present embodiment, the first corner cutting edge 43 has a negative axial rake when viewed from the side. Also, the first corner cutting edge 43 may have a curved shape with a constant radius of curvature when the front surface 11 is viewed from the front.

[0051] The front side surface 11 has a second corner 45 located on the rear end 3B side and on the outer periphery side. When the front side surface 11 is a rectangle having four corners and four sides, the corner of the four corners located on the rear end 3B side and on the outer periphery side corresponds to the second corner 45. The cutting edge 24 may also have a second corner cutting edge 47 located at the second corner 45. In the cutting tool 1 shown in this embodiment, the second corner cutting edge 47 is connected to the second peripheral cutting edge 31. More specifically, the second corner cutting edge 47 is connected to the second straight cutting edge 31A.

[0052] In the cutting tool 1 according to the present embodiment, the second corner cutting edge 47 has a positive axial rake when viewed from the side. Also, the second corner cutting edge 47 may have a curved shape with a constant radius of curvature when the front surface 11 is viewed from the front.

[0053] In a side view, the first peripheral cutting edge 29 passes through an end Q2 located on the tip 3A side of the holder 3 and intersects with a line perpendicular to the rotation axis O1. Specifically, in the example shown in Fig. 3, the first peripheral cutting edge 29 passes through an end Q2 located on the tip 3A side of the holder 3 and intersects with a line S3 perpendicular to the rotation axis O1.

[0054] In this case, the thrust force acting in the direction of the rear end 3B during cutting will not become too small, and the risk of misalignment of the cutting edge can be further reduced.

[0055] The apex 27 may be located closer to the tip 3A than the through hole 23. Specifically, as shown in an example in Fig. 3, the apex 27 may be located closer to the tip 3A than a straight line S4 that passes through an end Q3 located closer to the tip 3A of the through hole 23 and is perpendicular to the rotation axis O1. In addition, when the insert 5 has multiple through holes 23, the evaluation is performed for the through hole 23 located closest to the tip 3A.

[0056] In such a case, after the cutting edge 24 comes into contact with the workpiece, it is possible to suppress an increase in cutting load on the side of the tip 3A relative to the first contact point P1.

[0057] The absolute value of the magnitude of the axial rake angle θ1 of the first peripheral cutting edge 29 may be larger than the absolute value of the magnitude of the axial rake angle θ2 of the second peripheral cutting edge 31. Specifically, the difference between the two absolute values ​​may be 3° to 15°.

[0058] Generally, when the absolute value of the axial rake angle is large, the thrust force also becomes large, so by relatively increasing the axial rake angle θ1 of the first peripheral cutting edge 29, which is shorter than the second peripheral cutting edge 31, it is possible to balance the magnitude of the thrust force acting on the first peripheral cutting edge 29 and the magnitude of the thrust force acting on the second peripheral cutting edge 31. As a result, the risk of the peripheral cutting edge 25 becoming misaligned can be further reduced.

[0059] In addition to the above case, i.e., when the axial rake angle θ2 of the second peripheral cutting edge 31 is relatively small, when the second peripheral cutting edge 31 extends to the second corner cutting edge 47, the thickness of the insert 5 in the rotational direction O2 can be ensured on the side of the rear end 3B from the apex 27.

[0060] The front side surface 11 has a first side 51 connected to the outer side surface 15. When the front side surface 11 is viewed from the front, the first side 51 has a linear shape and refers to the entire ridge line between the front side surface 11 and the outer side surface 15. The first side 51 is sandwiched between the first corner 41 and the second corner 45 and is connected to the first corner 41 and the second corner 45. In other words, the peripheral cutting edge 25 is sandwiched between the first corner cutting edge 43 and the second corner cutting edge 47 and is connected to the first corner cutting edge 43 and the second corner cutting edge 47.

[0061] 7, the peripheral cutting edge 25 is located on the first side 51. In the cutting tool 1 shown in this embodiment, the length of the peripheral cutting edge 25 is equal to the length of the first side 51, but this is not necessarily the case and may be, for example, 1 / 2 to 3 / 4 of the length of the first side 51.

[0062] The cutting edge 24 has a tip edge 53 located at the intersection of the front side surface 11 and the tip surface 19. The tip edge 53 has a linear first tip edge 53A. The first tip edge 53A approaches the rear end 3B as it moves from the inner peripheral side to the outer peripheral side.

[0063] The tip blade 53 has a linear second tip blade 53B. The second tip blade 53B is located closer to the inner periphery than the first tip blade 53A. The second tip blade 53B approaches the tip 3A from the inner periphery toward the outer periphery.

[0064] In the cutting tool 1 shown in this embodiment, the tip edge 53 is connected to the first corner cutting edge 43. More specifically, the first tip edge 53A is connected to the first corner cutting edge 43. The first tip edge 53A may be connected to the second tip edge 53B, or the tip edge 53 may have a curved third tip edge 53C between the first tip edge 53A and the second tip edge 53B.

[0065] In the cutting tool 1 shown in the present embodiment, the insert 5 is a substantially rectangular parallelepiped, but the shape of the insert 5 is not limited to a substantially rectangular parallelepiped. For example, if the insert 5 is a substantially triangular prism, the rear end surface 21 described above may not exist, the front side surface 11, the rear side surface 13, and the tip surface 19 may be substantially rectangular, and the inner side surface 17 and the outer side surface 15 may be substantially triangular. Furthermore, the insert 5 may have a ridgeline between the front side surface 11 and the rear side surface 13 on the rear end 3B side, and the second corner cutting edge 47 may be located at the intersection of the second corner 45 and the front side surface 11 and the rear side surface 13.

[0066] Examples of materials for the insert 5 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.

[0067] 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).

[0068] The surface of the insert 5 may be coated with a film by chemical vapor deposition (CVD) or physical vapor deposition (PVD). Examples of the coating composition include titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and alumina (Al2O3).

[0069] The holder 3 may be made of steel, cast iron, aluminum alloy, or the like.

[0070] <Method of manufacturing machined products> Next, a non-limiting method for manufacturing the one-surface machined product 103 according to the present disclosure will be described with reference to FIGS.

[0071] The machined product 103 may be produced by cutting the workpiece 101. A manufacturing method for the machined product 103 may include the following steps: (1) rotating a cutting tool 1, such as the one typified by the non-limiting embodiment described above; (2) bringing the rotating cutting tool 1 into contact with the workpiece 101; (3) a step of separating the cutting tool 1 from the workpiece 101; may also be provided.

[0072] Specifically, first, as shown in a non-limiting example in Fig. 10, the cutting tool 1 may be rotated around the rotation axis O1 in the O2 direction while being relatively brought close to the workpiece 101. Next, as shown in a non-limiting example in Fig. 11, the cutting tool 1 is brought into contact with the workpiece 101, and the workpiece 1 12, the cutting tool 1 may be moved relatively far away from the workpiece 101.

[0073] By going through the above steps, it is possible to obtain a machined product 103 with a highly accurate finished surface. Specifically, in the manufacturing method of the machined product 103, when the cutting tool 1 having the insert 5 is used, the insert 5 can be stably fixed to the holder 3, and therefore excellent workability can be exhibited. As a result, it is possible to obtain a machined product 103 with a highly accurate finished surface.

[0074] In the non-limiting example shown in FIGS. 10 to 12, the workpiece 101 is fixed and the cutting tool 1 is moved in each step, but the present invention is not limited to this configuration.

[0075] For example, in step (1), the workpiece 101 may be brought closer to the cutting tool 1. Similarly, in step (3), the workpiece 101 may be moved away from the cutting tool 1. When continuing the cutting process, the cutting tool 1 may be kept rotating, and the step of bringing the insert 5 into contact with different locations on the workpiece 101 may be repeated.

[0076] Examples of the material of the workpiece 101 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0077] In one embodiment, (1) a cutting tool is a cutting tool extending from a front end to a rear end along a rotation shaft, and includes a holder having a pocket located on the front end side, an insert attached to the pocket, and a fixture for fixing the insert to the holder, and the insert has a front side surface located forward in a rotation direction of the rotation shaft, a rear side surface located rearward in the rotation direction, an outer side surface located on the outer periphery side and connected to the front side and the rear side, an inner side surface located on the inner periphery side and connected to the front side and the rear side, and a through hole penetrating from the outer side surface to the inner side surface and into which the fixture is inserted. , and a cutting edge located at the outer edge of the front side surface, the cutting edge having a peripheral cutting edge located at the intersection of the front side surface and the outer side surface, the peripheral cutting edge having an apex located at the front most position in the rotation direction, a first peripheral cutting edge extending from the apex toward the tip end and having a negative axial rake angle, and a second peripheral cutting edge extending from the apex toward the rear end and having a positive axial rake angle, the pocket having a seating surface abutting the rear side surface and a fixing hole facing the outer periphery and into which the fixing device is inserted, at least a portion of the seating surface being located closer to the tip end than the apex, and the second peripheral cutting edge being longer than the first peripheral cutting edge.

[0078] (2) In the cutting tool of (1) above, the bearing surface may have a flat portion, and at least a portion of the flat portion may be located closer to the tip than the apex.

[0079] (3) In the cutting tool of (1) or (2) above, the first peripheral cutting edge may, when viewed from the side, have a first curved cutting edge having a curved shape extending from the top portion toward the tip, and a first straight cutting edge having a linear shape extending from the first curved cutting edge toward the tip, and the second peripheral cutting edge may, when viewed from the side, have a second curved cutting edge having a curved shape extending from the top portion toward the rear end, and a second straight cutting edge having a linear shape extending from the second curved cutting edge toward the rear end.

[0080] (4) In the cutting tool of (3) above, the first curved edge may be longer than the second curved edge.

[0081] (5) In the cutting tool according to any one of (1) to (4), the front side surface is The cutting edge may have a first side located on the leading end side, a first corner connected to the first side on the leading end side, and a second corner connected to the first side on the trailing end side, and the peripheral cutting edge may be located on the first side, and the cutting edge may further have a first corner cutting edge located at the first corner and a second corner cutting edge located at the second corner, and the first peripheral cutting edge may be connected to the first corner cutting edge, and the second peripheral cutting edge may be connected to the second corner cutting edge.

[0082] (6) In the cutting tool according to any one of (1) to (5) above, at least a portion of the first peripheral cutting edge may be located closer to the tip than the holder.

[0083] (7) In any of the cutting tools (1) to (6) above, the apex may be located closer to the tip than the through hole.

[0084] (8) In any one of the cutting tools (1) to (7) above, the absolute value of the axial rake angle of the first peripheral cutting edge may be greater than the absolute value of the axial rake angle of the second peripheral cutting edge.

[0085] (9) In any of the cutting tools (1) to (8) above, the front surface may have a first edge connected to the outer surface, and when the front surface is viewed from the front, the first edge may be linear.

[0086] (10) The method includes the steps of rotating any one of the cutting tools (1) to (9) above, bringing the cutting tool into contact with a workpiece, and moving the cutting tool away from the workpiece.

[0087] The invention according to the present disclosure has been described above based on the drawings and embodiments. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art can easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure. [Explanation of symbols]

[0088] 1...cutting tools 3. Holder 3A...Tip 3B...Rear end 5. Insert 7... Fixture 9 pockets 11 Front side 11A...Front plane 13... Posterior side 13A...Back plane 15...Outer surface 17. Inner surface 19...Tip surface 21...Rear end surface 23...Through hole 24 cutting edge 25...Peripheral blade 27...Top 29...1st peripheral blade 29A...1st straight blade 29B...1st curved blade 31...2nd peripheral blade 31A...Second straight blade 31B...Second curved blade 35···Seat 35A...Plane part 37...Restriction surface 39...Fixing hole 41...first corner 43... 1st corner cutting edge 45...Second corner 47···Second corner cutting edge 51...First side 53 Tip blade 53A···First tip blade 53B···Second tip blade 53C...Third tip blade 101...Work material 103...Cutting workpiece O1 Rotation axis O2 Rotation direction O10: A straight line parallel to the axis of rotation N1~N3...center axis S1~S4: Virtual lines T1. T2... Virtual extension line P1, P2...Contact point L1~L6...length Q1 to Q3: Ends θ1, θ2...axial rake angle

Claims

1. A cutting tool extending from a tip end to a rear end along a rotation axis, a holder having a pocket located on the side of the tip; an insert attached to the pocket; a fastener for fastening the insert to the holder; The insert is a front side surface located forward in the rotation direction of the rotation shaft; a rear side surface located rearward in the rotation direction; an outer surface located on the outer periphery and connected to the front surface and the rear surface; an inner surface located on the inner circumferential side and connected to the front surface and the rear surface; a through hole that penetrates from the outer surface to the inner surface and into which the fixing device is inserted; a cutting edge located at an outer edge of the front side surface, The cutting edge has a peripheral cutting edge located at the intersection of the front side surface and the outer side surface, The peripheral cutting edge is a top portion located most forward in the rotation direction; a first peripheral cutting edge extending from the apex toward the tip and having a negative axial rake angle; a second peripheral cutting edge extending from the top end toward the rear end and having a positive axial rake angle; The pocket is a seating surface abutting the rear side surface; a fixing hole facing the outer circumferential side and into which the fixing device is inserted, At least a portion of the seating surface is located closer to the tip than the apex, The second peripheral cutting edge is longer than the first peripheral cutting edge, When viewed from the side, the first peripheral cutting edge has a first curved blade having a curved shape extending from the top portion toward the tip portion; a first straight blade having a straight shape extending from the first curved blade toward the tip, When viewed from the side, the second peripheral cutting edge has a second curved blade having a curved shape extending from the top toward the rear end; a second straight edge having a linear shape extending from the second curved edge toward the rear end.

2. The cutting tool of claim 1 , wherein the first curved edge is longer than the second curved edge.

3. The front side surface is a first side located on the outer periphery side; a first corner connected to the first side on the tip side; a second corner connected to the first side on the rear end side, The peripheral cutting edge is located on the first side, The cutting blade is a first corner cutting edge located at the first corner; a second corner cutting edge located at the second corner, the first peripheral cutting edge is connected to the first corner cutting edge, The cutting tool according to claim 1 , wherein the second peripheral cutting edge is connected to the second corner cutting edge.

4. The cutting tool according to claim 1 , wherein at least a portion of the first peripheral cutting edge is located closer to the tip than the holder.

5. The cutting tool according to claim 1 , wherein the absolute value of the axial rake angle of the first peripheral cutting edge is greater than the absolute value of the axial rake angle of the second peripheral cutting edge.

6. A cutting tool extending from a tip end to a rear end along a rotation axis, a holder having a pocket located on the side of the tip; an insert attached to the pocket; a fastener for fastening the insert to the holder; The insert is a front side surface located forward in the rotation direction of the rotation shaft; a rear side surface located rearward in the rotation direction; an outer surface located on the outer periphery and connected to the front surface and the rear surface; an inner surface located on the inner circumferential side and connected to the front surface and the rear surface; a through hole that penetrates from the outer surface to the inner surface and into which the fixing device is inserted; a cutting edge located at an outer edge of the front side surface, The cutting edge has a peripheral cutting edge located at the intersection of the front side surface and the outer side surface, The peripheral cutting edge is a top portion located most forward in the rotation direction; a first peripheral cutting edge extending from the apex toward the tip and having a negative axial rake angle; a second peripheral cutting edge extending from the top end toward the rear end and having a positive axial rake angle; The pocket is a seating surface abutting the rear side surface; a fixing hole facing the outer circumferential side and into which the fixing device is inserted, At least a portion of the seating surface is located closer to the tip than the apex, The second peripheral cutting edge is longer than the first peripheral cutting edge, The front side surface is a first side located on the outer periphery side; a first corner connected to the first side on the tip side; a second corner connected to the first side on the rear end side, The peripheral cutting edge is located on the first side, The cutting blade is a first corner cutting edge located at the first corner; a second corner cutting edge located at the second corner, the first peripheral cutting edge is connected to the first corner cutting edge, A cutting tool, wherein the second peripheral cutting edge connects with the second corner cutting edge.

7. The cutting tool according to claim 6 , wherein at least a portion of the first peripheral cutting edge is located closer to the tip than the holder.

8. The cutting tool according to claim 6 , wherein the absolute value of the axial rake angle of the first peripheral cutting edge is greater than the absolute value of the axial rake angle of the second peripheral cutting edge.

9. A cutting tool extending from a tip end to a rear end along a rotation axis, a holder having a pocket located on the side of the tip; an insert attached to the pocket; a fastener for fastening the insert to the holder; The insert is a front side surface located forward in the rotation direction of the rotation shaft; a rear side surface located rearward in the rotation direction; an outer surface located on the outer periphery and connected to the front surface and the rear surface; an inner surface located on the inner circumferential side and connected to the front surface and the rear surface; a through hole that penetrates from the outer surface to the inner surface and into which the fixing device is inserted; a cutting edge located at an outer edge of the front side surface, The cutting edge has a peripheral cutting edge located at the intersection of the front side surface and the outer side surface, The peripheral cutting edge is a top portion located most forward in the rotation direction; a first peripheral cutting edge extending from the apex toward the tip and having a negative axial rake angle; a second peripheral cutting edge extending from the top end toward the rear end and having a positive axial rake angle; The pocket is a seating surface abutting the rear side surface; a fixing hole facing the outer circumferential side and into which the fixing device is inserted, At least a portion of the seating surface is located closer to the tip than the apex, The second peripheral cutting edge is longer than the first peripheral cutting edge, A cutting tool, wherein at least a portion of the first peripheral cutting edge is located closer to the tip than the holder.

10. The cutting tool according to claim 9 , wherein the absolute value of the axial rake angle of the first peripheral cutting edge is greater than the absolute value of the axial rake angle of the second peripheral cutting edge.

11. A cutting tool extending from a tip end to a rear end along a rotation axis, a holder having a pocket located on the side of the tip; an insert attached to the pocket; a fastener for fastening the insert to the holder; The insert is a front side surface located forward in the rotation direction of the rotation shaft; a rear side surface located rearward in the rotation direction; an outer surface located on the outer periphery and connected to the front surface and the rear surface; an inner surface located on the inner circumferential side and connected to the front surface and the rear surface; a through hole that penetrates from the outer surface to the inner surface and into which the fixing device is inserted; 、 a cutting edge located at an outer edge of the front side surface, The cutting edge has a peripheral cutting edge located at the intersection of the front side surface and the outer side surface, The peripheral cutting edge is a top portion located most forward in the rotation direction; a first peripheral cutting edge extending from the apex toward the tip and having a negative axial rake angle; a second peripheral cutting edge extending from the top end toward the rear end and having a positive axial rake angle; The pocket is a seating surface abutting the rear side surface; a fixing hole facing the outer circumferential side and into which the fixing device is inserted, At least a portion of the seating surface is located closer to the tip than the apex, The second peripheral cutting edge is longer than the first peripheral cutting edge, A cutting tool, wherein the absolute value of the axial rake angle of the first peripheral cutting edge is greater than the absolute value of the axial rake angle of the second peripheral cutting edge.

12. A step of rotating the cutting tool according to any one of claims 1 to 11; contacting the cutting tool with a workpiece; and removing the cutting tool from the workpiece.

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