Cutting insert, cutting tool, and method for producing machined product

Abstract

In a cutting insert according to one non-limiting aspect of the present disclosure, a tip blade has a first end part that is located on the first-side-surface side and a second end part that is located on the second-side-surface side and that is closer to a body part than the first end part. A tip surface has a flank surface that is located along the tip blade, a constraining surface that is located lower than the flank surface, and a connection surface that is located between the flank surface and the constraining surface and that is inclined with respect to the flank surface and the constraining surface. The connection surface has a first connection surface that is located below the first end part and a second connection surface that is located below the second end part. The inclination angle of the first connection surface is larger than the inclination angle of the flank surface. The inclination angle of the second connection surface is smaller than the inclination angle of the flank surface.

Description

Cutting insert, cutting tool, and method for manufacturing machined product CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2023-151905, filed on September 20, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a cutting insert and a cutting tool used in cutting a workpiece, and a method for manufacturing a machined product. Examples of cutting include turning and milling. Examples of turning include internal diameter machining, external diameter machining, grooving, and cut-off.

[0003] Examples of cutting tools used when cutting a workpiece include those described in Japanese Patent Laid-Open Nos. 8-229705 (Patent Document 1) and 2009-012117 (Patent Document 2). The cutting tools described in Patent Documents 1 and 2 have a holder and a cutting insert (hereinafter simply referred to as an "insert"). One known example of the insert is a rod-shaped insert extending along a central axis, having a main body portion located in the center in a direction along the central axis, and a pair of cutting portions located at both ends in a direction along the central axis.

[0004] The end faces of the pair of cutting portions are each provided with a flank area and a constraint area. When one of the pair of cutting portions is used for cutting, the constraint area of ​​the other of the pair of cutting portions can be used for constraint to the holder.

[0005] For example, when the cutting edge is inclined relative to the central axis, as in the case of an insert for cut-off machining, the flank area and the constraint area are likely to have a twisted relationship. In this case, in the inserts described in Patent Documents 1 and 2, the constraint area is set to match the portion of the flank area that is close to the main body. Therefore, the portion of the cutting edge that is far from the main body protrudes significantly from the constraint area. In such a configuration, the strength of the portion of the cutting edge that is far from the main body may be reduced.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an insert having excellent durability.

[0007] A non-limiting one-sided cutting insert of the present disclosure has a rod shape extending along a central axis from a leading end to a trailing end. The cutting insert has a body portion located at the center in a direction along the central axis, a first cutting portion located closer to the leading end than the body portion, and a second cutting portion located closer to the trailing end than the body portion. The first cutting portion has a leading end surface located closer to the leading end, an upper surface extending from the leading end surface toward the body portion, a first side surface extending from the leading end surface toward the body portion, a second side surface extending from the leading end surface toward the body portion and located opposite the first side surface, and a tip cutting edge located at an intersection of the leading end surface and the upper surface.

[0008] The cutting edge has a first end located on the first side surface and a second end located on the second side surface and closer to the main body than the first end. The cutting edge has a flank located along the cutting edge, a constraint surface located below the flank surface, and a connecting surface located between the flank surface and the constraint surface and inclined relative to the flank surface and the constraint surface. The connecting surface has a first connecting surface located below the first end and a second connecting surface located below the second end. The inclination angle of the first connecting surface is greater than the inclination angle of the flank surface. The inclination angle of the second connecting surface is smaller than the inclination angle of the flank surface.

[0009] 1 is a perspective view showing an unlimited single-sided cutting insert of the present disclosure; FIG. 2 is an enlarged view of an area II shown in FIG. 1; FIG. 3 is a perspective view of the cutting insert shown in FIG. 1 from another direction, and is an enlarged view of the tip side; FIG. 4 is a plan view of the upper surface of the cutting insert shown in FIG. 1 from the front; FIG. 5 is an enlarged view of an area V shown in FIG. 4; FIG. 6 is a side view of the cutting insert shown in FIG. 4 from direction VI; FIG. 7 is a plan view of the cutting insert shown in FIG. 4 from direction VII; FIG. 8 is the same plan view as FIG. 7; FIG. 9 is a cross-sectional view of cross section IX of the cutting insert shown in FIG. 8; FIG. 10 is a cross-sectional view of cross section XI of the cutting insert shown in FIG. 8; FIG. 11 is the same cross-sectional view as FIG. 11; FIG. 12 is a perspective view of an unlimited single-sided cutting tool of the present disclosure; FIG. 13 is a schematic view showing one step in a method for manufacturing an unlimited single-sided machined product of the present disclosure; FIG. 14 is a schematic view showing one step in a method for manufacturing an unlimited single-sided machined product of the present disclosure; FIG. 15 is a schematic view showing one step in a method for manufacturing an unlimited single-sided machined product of the present disclosure; FIG. 16 is a schematic view showing one step in a method for manufacturing an unlimited single-sided machined product of the present disclosure;

[0010] <Cutting Insert> Hereinafter, a non-limiting one-sided cutting insert 1 (hereinafter also simply referred to as "insert 1") of the present disclosure 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 the embodiment in a simplified form. Therefore, the insert 1 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 and the dimensional ratios of the components.

[0011] The insert 1 may have a rod shape extending along the central axis O1 from the front end 1a to the rear end 1b, as in the non-limiting example shown in Figures 1 to 12. The insert 1 may have a prismatic shape. The insert 1 may have a quadrangular prism shape. Note that the quadrangular prism shape may be roughly a quadrangular prism shape, and does not necessarily have to be a quadrangular prism shape in the strict sense.

[0012] The insert 1 may have a body portion 3, a first cutting portion 5 and a second cutting portion 7, as shown in non-limiting examples in FIGS.

[0013] The main body portion 3 may be located at the center of the insert 1 in the direction along the central axis O1. The main body portion 3 can function as a portion that is fixed to the holder when the insert 1 is attached to the holder.

[0014] The first cutting portion 5 may be located closer to the tip 1a than the main body portion 3. The second cutting portion 7 may be located closer to the rear end 1b than the main body portion 3. The first cutting portion 5 and the second cutting portion 7 are capable of contacting the workpiece and can function as portions that play a major role in cutting the workpiece (e.g., cut-off). When one of the first cutting portion 5 and the second cutting portion 7 is used for cutting, the other of the first cutting portion 5 and the second cutting portion 7 can be used for restraining the workpiece to the holder.

[0015] The second cutting unit 7 may have the same configuration as the first cutting unit 5. Therefore, the description of the first cutting unit 5 may be used to understand the configuration of the second cutting unit 7.

[0016] The first cutting portion 5 may have a tip surface 9, an upper surface 11, a first side surface 13, a second side surface 15, and a tip cutting edge 17, as shown in a non-limiting example in FIGS.

[0017] The tip surface 9 may be located on the tip 1 a side. The upper surface 11 may extend from the tip surface 9 toward the main body portion 3.

[0018] The upper surface 11 is a convenient expression and does not indicate an upward direction. For example, the upper surface 11 does not need to face upward when the insert 1 is used. This also applies to other parts that include the expressions "up" and "down." Furthermore, the positional relationship in the up-down direction may be specified by defining a direction perpendicular to the central axis O1, from the central axis O1 toward the upper surface 11 as "upward," and a direction from the upper surface 11 toward the central axis O1 as "downward."

[0019] The first side surface 13 may extend from the tip surface 9 toward the main body portion 3. The second side surface 15 may extend from the tip surface 9 toward the main body portion 3. The second side surface 15 may be located on the opposite side of the first side surface 13.

[0020] The tip cutting edge 17 may be located at the intersection of the tip surface 9 and the top surface 11. The tip cutting edge 17 may be located over the entire intersection, or may be located over only a portion of the intersection. The tip cutting edge 17 can be used to cut a workpiece when manufacturing a machined product using the insert 1. The tip cutting edge 17 may also be generally referred to as a leading cutting edge or a main cutting edge.

[0021] The tip cutting edge 17 may have a linear shape or a curved shape when viewed from the tip or from the top. Furthermore, the tip cutting edge 17 may have a shape that combines a linear shape and a curved shape when viewed from the tip or from the top. For example, as in a non-limiting example shown in FIG. 7, the tip cutting edge 17 may have a concave curved shape when viewed from the tip. Furthermore, as in a non-limiting example shown in FIG. 5, the tip cutting edge 17 may have a concave curved shape when viewed from the top. Note that the tip view may refer to a state viewed from the tip 1a side. Furthermore, the top view may refer to a state viewed from the top surface 11 side.

[0022] The tip cutting edge 17 may have a first end 17a and a second end 17b, as shown in a non-limiting example in FIG. 5 . The first end 17a may be located on the side of the first side surface 13. The second end 17b may be located on the side of the second side surface 15. The second end 17b may be located closer to the main body 3 than the first end 17a. In these cases, the tip cutting edge 17 is likely to be inclined with respect to the central axis O1. The first end 17a may be located closer to the first side surface 13 than the central axis O1. The second end 17b may be located closer to the second side surface 15 than the central axis O1.

[0023] The first end 17a is not limited to the end point of the cutting edge 17 on the side of the first side face 13. As shown in Fig. 5 as a non-limiting example, the first end 17a may refer to a region having a width on the side of the first side face 13. Similarly, the second end 17b is not limited to the end point of the cutting edge 17 on the side of the second side face 15. As shown in Fig. 5 as a non-limiting example, the second end 17b may refer to a region having a width on the side of the second side face 15.

[0024] The tip surface 9 may have a clearance surface 19, a constraint surface 21, and a connecting surface 23, as shown in a non-limiting example in FIG.

[0025] The flank 19 may be located along the cutting edge 17. The flank 19 can function as a portion that avoids contact with the workpiece and reduces cutting resistance. The flank 19 may be connected to the cutting edge 17. The flank 19 may have a flat configuration, as shown in a non-limiting example in FIG. 2. Flat does not necessarily have to be flat in the strict sense. The flank 19 may be approximately flat, and may be slightly curved or have slight irregularities that are not noticeable when the insert 1 is viewed as a whole. For example, the flank 19 may have slight irregularities of about several tens of μm.

[0026] The constraint surface 21 may be located below the flank surface 19. The constraint surface 21 may mean that it can be used as a surface that is constrained by the holder when the insert 1 is attached to the holder. In other words, the constraint surface 21 is not necessarily a surface that is constrained by the holder when the first cutting portion 5 is used. The constraint surface 21 may have a flat configuration, as in the non-limiting example shown in FIG. 2. Flat does not necessarily have to be flat in the strict sense. The constraint surface 21 may be approximately flat, similar to the flank surface 19. In the non-limiting example shown in FIG. 2, the flat flank surface 19 is in a twisted relationship with respect to the flat constraint surface 21.

[0027] The connecting surface 23 may be located between the relief surface 19 and the constraint surface 21. The connecting surface 23 may be inclined with respect to the relief surface 19 and the constraint surface 21, as shown in non-limiting examples in Figures 9 and 11. Note that the connecting surface 23 may be connected to the relief surface 19 and the constraint surface 21, respectively.

[0028] 7, the connecting surface 23 may have a first connecting surface 25 and a second connecting surface 27. The first connecting surface 25 may be located below the first end 17a. The second connecting surface 27 may be located below the second end 17b.

[0029] Note that, "the first connecting surface 25 is located below the first end 17a" may mean that the first connecting surface 25 appears in a cross section passing through the first end 17a and taken along the central axis O1, as in the non-limiting example shown in Fig. 9. "The second connecting surface 27 is located below the second end 17b" may mean that the second connecting surface 27 appears in a cross section passing through the second end 17b and taken along the central axis O1, as in the non-limiting example shown in Fig. 11.

[0030] Here, the inclination angle θ25 of the first connecting surface 25 may be larger than the inclination angle θ19 of the flank 19, as in a non-limiting example shown in Fig. 10 . Furthermore, the inclination angle θ27 of the second connecting surface 27 may be smaller than the inclination angle θ19 of the flank 19, as in a non-limiting example shown in Fig. 12 . Figures 10 and 12 may each be a cross section parallel to the central axis O1 and along the up-down direction. When a virtual plane is set that is equidistant from a pair of side surfaces of the main body 3, Figures 10 and 12 may be parallel to this virtual plane.

[0031] The inclination angles θ19, θ25, and θ27 of the flank 19, the first connecting surface 25, and the second connecting surface 27 can be evaluated as follows: First, in the cross sections shown in Figures 10 and 12, an imaginary line L1 perpendicular to the central axis O1 is set. The angles formed by the flank 19, the first connecting surface 25, and the second connecting surface 27 with this imaginary line L1 correspond to the inclination angles θ19, θ25, and θ27 described above.

[0032] When the flank 19 is inclined so as to approach the main body 3 as it moves away from the cutting edge 17, the inclination angle θ19 is a positive value, and when the flank 19 is inclined so as to move away from the main body 3 as it moves away from the cutting edge 17, the inclination angle θ19 is a negative value. The same is true for the first connecting surface 25 and the second connecting surface 27, and it can be evaluated whether the inclination angles θ25, θ27 are positive or negative depending on the inclination direction of these surfaces.

[0033] 10 , when the flank 19 is shown as a straight line in a cross-sectional view, the angle between this line and the above-mentioned imaginary line L1 can be evaluated as the inclination angle θ 19. Similarly, when the first connecting surface 25 is shown as a straight line in a cross-sectional view, the angle between this line and the above-mentioned imaginary line L1 can be evaluated as the inclination angle θ 25. The inclination angle 27 of the second connecting surface 27 can be evaluated in a similar manner.

[0034] When the connecting surface 23 has the above-described two-surface configuration (first connecting surface 25 and second connecting surface 27), the position of the constraint surface 21 is set so that it is located closer to the rear end 1b than the region of the flank 19 that protrudes most toward the tip 1a, and closer to the tip 1a than the region of the flank 19 that is recessed most toward the rear end 1b. This makes it possible to connect the flank 19 and the constraint surface 21, which are in such a positional relationship, with the connecting surface 23. This makes it possible to avoid a configuration in which the first end 17a of the tip cutting edge 17, which protrudes most toward the tip 1a, protrudes significantly from the constraint surface 21. This makes it easy to ensure the thickness of the first end 17a of the tip cutting edge 17, and the strength of the first end 17a is high. Therefore, the insert 1 has excellent durability.

[0035] When a cylindrical workpiece is to be cut, such as in a cut-off operation, the cylindrical shape of the workpiece makes it easier to ensure that the constraint surface 21, which is located farther from the cutting edge 17 than the flank 19, is farther away from the workpiece than the flank 19. Therefore, it is easier to avoid the constraint surface 21 coming into contact with the workpiece, even below the second end 17b of the cutting edge 17, which is pulled down furthest toward the rear end 1b.

[0036] The inclination angle θ25 of the first connecting surface 25 may be larger than the inclination angle θ21 of the restraint surface 21, as in a non-limiting example shown in Figure 10. The inclination angle θ27 of the second connecting surface 27 may be smaller than the inclination angle θ21 of the restraint surface 21, as in a non-limiting example shown in Figure 12. In these cases, it is easy to prevent the restraint surface 21 from being pulled down too far toward the rear end 1b. Therefore, the insert 1 is easily held stably in the holder.

[0037] The inclination angle is not limited to a specific value. For example, the inclination angle θ25 of the first connecting surface 25 may be set to 10 to 45°. The inclination angle θ27 of the second connecting surface 27 may be set to 0 to 5°. The inclination angle θ19 of the relief surface 19 may be set to 3 to 10°. The inclination angle θ21 of the restraint surface 21 may be set to 1 to 10°. The inclination angle θ25 of the first connecting surface 25 may be larger than the inclination angle θ27 of the second connecting surface 27.

[0038] As shown in a non-limiting example in Figure 7, the width W25 of the first connection surface 25 in the height direction Y1 may increase as it approaches the first side surface 13. In this case, the inclination of the restraint surface 21 with respect to the central axis O1 is easily suppressed. Therefore, the restraint stability of the insert 1 in the holder is high. Note that the height direction Y1 may refer to the up-down direction of the insert 1.

[0039] 7, the width W27 of the second connecting surface 27 in the height direction Y1 may increase as it approaches the second side surface 15. In this case, the inclination of the restraining surface 21 with respect to the central axis O1 is easily suppressed. Therefore, the restraint stability of the insert 1 in the holder is high.

[0040] As shown in a non-limiting example in FIG. 7 , the maximum value of the width W27 of the second connecting surface 27 in the height direction Y1 may be greater than the maximum value of the width W25 of the first connecting surface 25 in the height direction Y1. In this case, it is easy to increase the inclination angle θ25 of the first connecting surface 25 and to decrease the inclination angle θ27 of the second connecting surface 27. This makes it easy to stably hold the insert 1 in the holder. In particular, when the flank surface 19 and the restraint surface 21 have a flat configuration, it is easy to increase the inclination angle θ25 of the first connecting surface 25 and to decrease the inclination angle θ27 of the second connecting surface 27.

[0041] The first connecting surface 25 may have a curved surface shape, as shown in non-limiting examples in Figures 2, 3, and 9. In this case, the first connecting surface 25 may have a first region 29 and a second region 31. The first region 29 may have a convex curved surface shape located along the relief surface 19. Furthermore, the second region 31 may have a concave curved surface shape located along the restraint surface 21.

[0042] In these cases, the first region 29 tends to ensure the thickness of the insert 1 directly below the leading edge 17. Therefore, the strength of the first end 17a of the leading edge 17 is high. Furthermore, the second region 31 tends to alleviate stress concentration at the boundary between the connecting surface 23 and the restraining surface 21. Therefore, the durability of the insert 1 tends to be improved.

[0043] The second region 31 may be connected to the first region 29. When the first connecting surface 25 has the first region 29 and the second region 31, a tangent line at the boundary between the first region 29 and the second region 31 may be set, and the inclination angle θ25 of the first connecting surface 25 may be determined by the angle of this tangent line relative to the virtual line L1.

[0044] The second connecting surface 27 may have a flat area 33, as shown in non-limiting examples in Figures 2, 3, and 11. The flat area 33 may be a flat surface area. Flat does not necessarily have to be flat in the strict sense. The flat area 33 may be generally flat, and may be slightly curved or have slight irregularities that are not noticeable when the insert 1 is viewed as a whole. For example, the flat area 33 may have slight irregularities of about several tens of micrometers.

[0045] As shown in a non-limiting example in FIGS. 11 and 12 , the flat area 33 may have a smaller inclination angle than the flank 19 and the restraint surface 21. In this case, the portion of the flat area 33 that is not in contact with the holder restraint surface and is restrained by the holder tends to be wider. As a result, a wider surface area of ​​the flat area 33 is pressed by the holder, which tends to improve cutting stability. Note that when the second connecting surface 27 has the flat area 33, the inclination angle θ27 of the second connecting surface 27 may be determined by the angle of the flat area 33 with respect to the virtual straight line L1. The flat area 33 may have the largest area on the second connecting surface 27.

[0046] 7, the upper end 25a of the first connecting surface 25 may be located higher than the upper end 27a of the second connecting surface 27. In this case, it is easy to ensure a large area for each of the clearance surface 19 and the restraint surface 21 while maintaining the area of ​​the connecting surface 23. The upper end may refer to the uppermost portion of the portion to be evaluated.

[0047] 7, the lower end 25b of the first connecting surface 25 may be located higher than the lower end 27b of the second connecting surface 27. In this case, it is easy to ensure a large area for each of the relief surface 19 and the restraint surface 21 while maintaining the area of ​​the connecting surface 23. The lower end may refer to the lowest portion of the part to be evaluated.

[0048] As shown in a non-limiting example in FIG. 7 , the second connecting surface 27 may be connected to the first connecting surface 25. In this case, the areas of the first connecting surface 25 and the second connecting surface 27 are likely to be larger than when another surface is present between the first connecting surface 25 and the second connecting surface 27. Therefore, the effects of the connecting surface 23 having the first connecting surface 25 and the effects of the connecting surface 23 having the second connecting surface 27 can be further enhanced. From the viewpoint of avoiding concentration of cutting loads at the boundary between the first connecting surface 25 and the second connecting surface 27, the first connecting surface 25 and the second connecting surface 27 may be smoothly connected. Here, being smoothly connected may mean that no ridgeline that can be discerned visually is formed at the boundary.

[0049] 7 , the end 27c of the second connecting surface 27 on the side of the first side surface 13 may be located higher than the end 25c of the first connecting surface 25 on the side of the second side surface 15. Also, the end 27c of the second connecting surface 27 may be located closer to the first side surface 13 than the end 25c of the first connecting surface 25. In these cases, the region of the second connecting surface 27 including the end 27c is likely to be located across the first connecting surface 25. As a result, the area of ​​the first connecting surface 25 can be reduced while ensuring the area of ​​the restraint surface 21, which makes it easier to maintain the strength of the insert 1.

[0050] 7 , the end 33a of the flat region 33 of the second connecting surface 27 on the side of the first side surface 13 may be located higher than the end 25c of the first connecting surface 25 on the side of the second side surface 15. Also, the end 33a of the flat region 33 may be located closer to the first side surface 13 than the end 25c of the first connecting surface 25. In these cases, the region of the flat region 33 including the end 33a is likely to be located across the first connecting surface 25. As a result, the area of ​​the first connecting surface 25 can be reduced while ensuring the area of ​​the restraint surface 21, which makes it easier to maintain the strength of the insert 1.

[0051] The area of ​​the second connecting surface 27 may be larger than the area of ​​the first connecting surface 25, as shown in a non-limiting example in FIG.

[0052] The insert 1 is not limited to a specific size. For example, the length of the insert 1 in the direction along the central axis O1 may be set to approximately 5 to 80 mm. Furthermore, the width of the insert 1 in the direction perpendicular to the central axis O1 when viewed from above may be set to approximately 2 to 20 mm. The height of the insert 1 in the direction perpendicular to the central axis O1 when viewed from the tip may be set to approximately 2 to 15 mm.

[0053] Examples of the material of the insert 1 include cemented carbide and cermet. Examples of the cemented carbide composition include WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co. Here, WC, TiC, and TaC may be hard particles, and Co may be a binder phase.

[0054] The cermet may be a sintered composite material in which a ceramic component is combined with a metal. An example of the cermet is a titanium compound mainly composed of titanium carbide (TiC) or titanium nitride (TiN). It goes without saying that the material of the insert 1 is not limited to the above composition.

[0055] The surface of the insert 1 may be coated with a coating using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, and the composition of the coating may include, for example, titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and alumina (Al2O3).

[0056] <Cutting Tool> Next, a non-limiting one-sided cutting tool 101 of the present disclosure will be described with reference to the drawings.

[0057] The cutting tool 101 may have a holder 103 and an insert 1, as in a non-limiting example shown in Fig. 13. When the cutting tool 101 has the insert 1, the insert 1 has excellent durability, and therefore, it is possible to exhibit high cutting performance.

[0058] The holder 103 may extend from the first end 103a toward the second end 103b. The extending direction of the holder 103 may coincide with the extending direction of the central axis O1 of the insert 1. The holder 103 may also be rod-shaped extending from the first end 103a toward the second end 103b. The holder 103 may also be shaped like a prism. The holder 103 may also be shaped like a square prism.

[0059] The holder 103 may have a pocket 105. The pocket 105 may be located on the side of the first end 103a. The insert 1 can be attached to the pocket 105.

[0060] The holder 103 may have an upper jaw 107 and a lower jaw 109 located on the side of the first end 103 a and spaced apart from each other, and the upper jaw 107 and the lower jaw 109 may form a pocket 105 .

[0061] The insert 1 may be located within the pocket 105. If the holder 103 has an upper jaw 107 and a lower jaw 109, the insert 1 may be sandwiched between the upper jaw 107 and the lower jaw 109.

[0062] The insert 1 may be positioned in the pocket 105 so that at least a part of the portion used as a cutting edge protrudes outward from the side of the first end 103 a of the holder 103. For example, the insert 1 may be positioned in the pocket 105 so that at least a part of the second cutting portion 7 protrudes outward from the side of the first end 103 a of the holder 103. In this case, the restraining surface 21 and the main body portion 3 of the first cutting portion 5 may abut against the holder 103.

[0063] The insert 1 may be attached to the pocket 105 by a screw 111. For example, the insert 1 may be attached to the pocket 105 by inserting the screw 111 into the screw holes of the upper jaw 107 and the lower jaw 109 and fastening the screw 111 to the screw holes.

[0064] Examples of materials for the holder 103 include steel and cast iron. When the material for the holder 103 is steel, the holder 103 has high toughness.

[0065] <Method for Manufacturing Machined Product> Next, a non-limiting method for manufacturing the machined product 201 having one surface according to the present disclosure will be described with reference to the drawings.

[0066] The machined product 201 may be produced by cutting a workpiece 203. A manufacturing method for the machined product 201 may include the following steps: (1) a step of rotating the workpiece 203; (2) a step of bringing the cutting tool 101, which is typified by the non-limiting embodiment described above, into contact with the rotating workpiece 203; and (3) a step of separating the cutting tool 101 from the workpiece 203.

[0067] Specifically, first, as in a non-limiting example shown in Fig. 14 , the workpiece 203 may be rotated around the axis O2, and the cutting tool 101 may be brought relatively close to the workpiece 203. Next, as in a non-limiting example shown in Fig. 15 and Fig. 16 , the cutting edge 17 of the cutting tool 101 may be brought into contact with the workpiece 203 to cut the workpiece 203. Then, as in a non-limiting example shown in Fig. 17 , the cutting tool 101 may be moved relatively away from the workpiece 203.

[0068] When the above-described steps are performed, the cutting tool 101 has the insert 1 with excellent durability, and therefore it is possible to obtain a machined product 201 with a highly accurate finished surface.

[0069] In the non-limiting example shown in FIGS. 14 to 17, the workpiece 203 is fixed and the cutting tool 101 is moved in each step, but the present invention is not limited to this configuration.

[0070] For example, in step (1), the workpiece 203 may be brought closer to the cutting tool 101. Also, in step (3), the workpiece 203 may be moved away from the cutting tool 101. When continuing the cutting process, the workpiece 203 may be kept rotating, and the step of bringing the cutting tool 101 into contact with different locations of the workpiece 203 may be repeated.

[0071] Examples of the material of the workpiece 203 include titanium alloys, aluminum, carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0072] The above provides examples of the non-limiting one-sided cutting insert 1, cutting tool 101, and method for manufacturing the machined product 201 of the present disclosure, but it goes without saying that the present disclosure is not limited to the above embodiments and can be any as long as it does not deviate from the gist of the present disclosure.

[0073] For example, the cutting insert 1, the cutting tool 101, and the manufacturing method of the machined product 201 may have the following configurations: [1] The cutting insert has a rod shape extending along a central axis from a tip end to a rear end, and has a main body portion located in the center in a direction along the central axis, a first cutting portion located closer to the tip end than the main body portion, and a second cutting portion located closer to the rear end than the main body portion, and the first cutting portion has a tip face located on the tip end side, an upper face extending from the tip face toward the main body portion, a first side face extending from the tip face toward the main body portion, a second side face extending from the tip face toward the main body portion and located on the opposite side to the first side face, and a tip cutting edge located at an intersection of the tip face and the upper face, and the tip

[0013] The cutting insert according to [1] above may have a first end portion located on the first side surface and a second end portion located on the second side surface and closer to the main body portion than the first end portion, and the tip surface has a flank surface located along the tip edge, a constraint surface located below the flank surface, and a connecting surface located between the flank surface and the constraint surface and inclined relative to the flank surface and the constraint surface, the connecting surface having a first connecting surface located below the first end portion and a second connecting surface located below the second end portion, the inclination angle of the first connecting surface being greater than the inclination angle of the flank surface and the inclination angle of the second connecting surface being smaller than the inclination angle of the flank surface. [2] In the cutting insert according to [1] above, the inclination angle of the first connecting surface may be greater than the inclination angle of the constraint surface and the inclination angle of the second connecting surface may be smaller than the inclination angle of the constraint surface. [3] In the cutting insert according to [1] or [2] above, the width of the first connecting surface in the height direction may increase as it approaches the first side surface. [4] In the cutting insert of any one of [1] to [3] above, the second connection surface may have a width in the height direction increasing toward the second side surface. [5] In the cutting insert of any one of [1] to [4] above, the first connection surface may have a curved shape, and may have a first region of a convex curved shape located along the flank surface and a second region of a concave curved shape located along the constraint surface. [6] In the cutting insert of any one of [1] to [5] above, the second connection surface may have a flat region having a smaller inclination angle than the flank surface and the constraint surface.[7] In the cutting insert of any one of [1] to [6] above, an upper end of the first connecting surface may be located higher than an upper end of the second connecting surface. [8] In the cutting insert of any one of [1] to [7] above, a lower end of the first connecting surface may be located higher than a lower end of the second connecting surface. [9] A cutting tool may have a holder extending from a first end to a second end and having a pocket located on the side of the first end, and a cutting insert of any one of [1] to [8] above located in the pocket.

[10] A method for manufacturing a machined product may include a step of rotating a workpiece, a step of bringing the cutting tool of [9] above into contact with the rotating workpiece, and a step of separating the cutting tool from the workpiece.

[0074] DESCRIPTION OF SYMBOLS 1 Cutting insert (insert) 1a Tip 1b Rear end 3 Main body 5 First cutting portion 7 Second cutting portion 9 Tip surface 11 Upper surface 13 First side surface 15 Second side surface 17 Tip cutting edge 17a First end 17b Second end 19 Flank surface 21 Restraint surface 23 Connection surface 25 First connection surface 25a Upper end 25b Lower end 25c End 27 Second connection surface 27a Upper end 27b Lower end 27c End 29 First region 31 Second region 33 Flat region 33a End 101 Cutting tool 103 Holder 103a First end 103b Second end 105 Pocket 107 Upper jaw 109: Lower jaw 111: Screw 201: Cutting workpiece 203: Workpiece O1: Central axis O2: Axis θ19: Inclination angle of relief surface θ21: Inclination angle of restraint surface θ25: Inclination angle of first connecting surface θ27: Inclination angle of second connecting surface L1: Virtual straight line Y1: Height direction

Claims

1. A rod-shaped cutting tool extending along a central axis from a tip to a rear end, comprising: a main body portion located at the center in a direction along the central axis; a first cutting portion located closer to the tip than the main body portion; and a second cutting portion located closer to the rear end than the main body portion, wherein the first cutting portion has: a tip surface located on the tip side; an upper surface extending from the tip surface towards the main body portion; a first side surface extending from the tip surface towards the main body portion; a second side surface extending from the tip surface towards the main body portion and located opposite to the first side surface; and a tip blade located at the intersection of the tip surface and the upper surface, wherein the tip blade has: a first end portion located on the side of the first side surface; and a second end portion located on the side of the second side surface and closer to the main body portion than the first end portion, wherein the tip surface has: a clearance surface located along the tip blade; a constraint surface located below the clearance surface; and a connection surface located between the clearance surface and the constraint surface and inclined with respect to the clearance surface and the constraint surface, The cutting insert has a first connection surface located below the first end portion and a second connection surface located below the second end portion, wherein an inclination angle of the first connection surface is greater than an inclination angle of the clearance surface, and an inclination angle of the second connection surface is smaller than an inclination angle of the clearance surface.

2. The cutting insert according to claim 1, wherein the inclination angle of the first connection surface is larger than the inclination angle of the restraint surface, and the inclination angle of the second connection surface is smaller than the inclination angle of the restraint surface.

3. A cutting insert as described in claim 1 or 2, wherein the first connection surface has a width in the height direction that increases toward the first side surface.

4. A cutting insert according to any one of claims 1 to 3, wherein the second connection surface has a width in the height direction that increases toward the second side surface.

5. A cutting insert according to any one of claims 1 to 4, wherein the first connection surface has a curved shape and includes a first region having a convex curved shape located along the relief surface, and a second region having a concave curved shape located along the restraint surface.

6. A cutting insert according to any one of claims 1 to 5, wherein the second connection surface has a flat area having a smaller inclination angle than the relief surface and the restraint surface.

7. A cutting insert according to any one of claims 1 to 6, wherein an upper end of the first connection surface is located higher than an upper end of the second connection surface.

8. A cutting insert according to any one of claims 1 to 7, wherein a lower end of the first connection surface is located higher than a lower end of the second connection surface.

9. A cutting tool comprising: a holder extending from a first end toward a second end and having a pocket located on the side of the first end; and a cutting insert according to any one of claims 1 to 8 located in the pocket.

10. A method for manufacturing a machined product, comprising the steps of: rotating a workpiece; bringing a cutting tool according to claim 9 into contact with the rotating workpiece; and removing the cutting tool from the workpiece.

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