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

Abstract

A cutting insert according to one non-limiting aspect of the present disclosure has a rod shape extending along a center axis, and includes a body portion, a first cutting portion, and a second cutting portion. The body portion includes a first lower groove extending along the center axis. The first cutting portion has a second lower groove extending along the center axis. The second cutting portion has a third lower groove extending along the center axis. The opening angle of the first lower groove is a first opening angle, the opening angle of the second lower groove is a second opening angle, and the opening angle of the third lower groove is a third opening angle, with the first opening angle being greater than the second opening angle and the third opening angle.

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. 2023-060565, filed on April 4, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a cutting insert for a cutting tool used in metal processing, etc. Specifically, the present disclosure relates to a so-called two-cornered dogbone-type cutting insert.

[0003] Known cutting inserts used in cutting workpieces such as metals include those described in International Publication No. 2020 / 175457 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2006-167874 (Patent Document 2). The cutting inserts described in Patent Documents 1 and 2 are held between upper and lower jaws of a holder. Furthermore, the cutting inserts described in Patent Documents 1 and 2 have grooves on their upper and lower surfaces so that they can be stably held by the holder.

[0004] The cutting insert is required to have both durability against the load applied when held in the holder and stability in holding by the holder.

[0005] A non-limiting one-sided cutting insert of the present disclosure has a rod shape extending from a first end to a second end along a central axis, and includes a main body, a first cutting portion located closer to the first end than the main body, and a second cutting portion located closer to the second end than the main body. The main body has a first upper surface having an upper groove extending along the central axis, and a first lower surface located opposite the first upper surface and having a first lower groove extending along the central axis. The first cutting portion has a first end surface located at the first end, a second upper surface extending from the first end surface to the first upper surface, a second lower surface extending from the first end surface to the first lower surface and having a second lower groove extending along the central axis, and a first cutting edge located at an intersection of the first end surface and the second upper surface. The second cutting portion has a second end surface located at the second end, a third upper surface extending from the second end surface to the first upper surface, a third lower surface extending from the second end surface to the first lower surface and having a third lower groove extending along the central axis, and a second cutting edge located at an intersection of the second end surface and the third upper surface, wherein an opening angle of the first lower groove in a cross section perpendicular to the central axis is a first opening angle, an opening angle of the second lower groove in a cross section perpendicular to the central axis is a second opening angle, and an opening angle of the third lower groove in a cross section perpendicular to the central axis is a third opening angle, and the first opening angle is larger than the second opening angle and the third opening angle.

[0006] 1 is a perspective view showing an unlimited one-sided cutting insert of the present disclosure. FIG. 1 is a plan view showing the cutting insert shown in FIG. 1 as viewed from above. FIG. 1 is a plan view showing the cutting insert shown in FIG. 1 as viewed from below. FIG. 2 is a side view of the cutting insert shown in FIG. 2 as viewed from the A1 direction. FIG. 3 is a cross-sectional view of the V-V section of the cutting insert shown in FIG. 4. FIG. 4 is a cross-sectional view of the VI-VI section of the cutting insert shown in FIG. 4. FIG. 5 is a cross-sectional view of the VII-VII section of the cutting insert shown in FIG. 4. FIG. 6 is an enlarged view of region VIII shown in FIG. 5. FIG. 7 is a perspective view showing an unlimited one-sided cutting tool of the present disclosure. FIG. 8 is an enlarged view of region X shown in FIG. 9. FIG. 10 is a schematic view showing one step in an unlimited method of manufacturing a machined product of one surface of the present disclosure. FIG. 11 is a schematic view showing one step in an unlimited method of manufacturing a machined product of one surface of the present disclosure.

[0007] <Cutting Insert> A non-limiting one-sided cutting insert 1 (hereinafter simply referred to as the insert 1) according to the present disclosure will be described in detail below with reference to the drawings. However, for the sake of convenience, the drawings 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. 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.

[0008] The insert 1 may have a rod shape extending from a first end 1a to a second end 1b along a central axis O1, as shown in a non-limiting example in Fig. 1. Specifically, the insert 1 may have a prismatic shape extending from the first end 1a to the second end 1b along the central axis O1.

[0009] The insert 1 may have a body portion 3, a first cutting portion 5, and a second cutting portion 7. The first cutting portion 5 may be located closer to the first end 1a than the body portion 3. The second cutting portion 7 may be located closer to the second end 1b than the body portion 3. In a non-limiting example shown in Figures 1 to 4, the first cutting portion 5 includes the first end 1a, and the second cutting portion 7 includes the second end 1b.

[0010] The first cutting portion 5 and the second cutting portion 7 may be portions that come into contact with the workpiece when the workpiece is cut using the insert 1 and play a main role in the cutting process. However, the first cutting portion 5 and the second cutting portion 7 do not need to come into contact with the workpiece at the same time, and it is sufficient if only one of the first cutting portion 5 or the second cutting portion 7 plays a main role in the cutting process. An insert 1 having cutting portions located at both ends in the direction along the central axis O1 in this way is generally called a two-cornered dogbone type.

[0011] The main body portion 3 may be a portion located at the center of the insert 1 in a direction along the central axis O1, and may be a portion that is restrained by a holder when the insert 1 is attached to the holder described below. The main body portion 3 may have a first upper surface 9 and a first lower surface 11. The first upper surface 9 may have an upper groove 13 extending along the central axis O1. The first lower surface 11 may be a portion located on the opposite side of the first upper surface 9, and may have a first lower groove 15 extending along the central axis O1.

[0012] Note that the first upper surface 9 and the first lower surface 11 are expressions for convenience and do not indicate an upward or downward direction. For example, the first upper surface 9 does not need to face upward when the insert 1 is used. Furthermore, the positional relationship in the upward and downward direction may be specified by defining a direction perpendicular to the central axis O1, that is, a direction from the central axis O1 toward the first upper surface 9, as "upward," and a direction from the central axis O1 toward the first lower surface 11, as "downward." These points are the same for other parts that include the expressions "upward" and "downward."

[0013] In a cross section perpendicular to the central axis O1, the upper groove 13 may have a V-shape that opens upward, and the first lower groove 15 may have a V-shape that opens downward. In a non-limiting example shown in Figure 5, the upper groove 13 has a concavely curved upper bottom surface 17 and a pair of upper restraint surfaces 19 that extend upward from the upper bottom surface 17. The upper bottom surface 17 may be the portion of the upper groove 13 closest to the central axis O1.

[0014] In a cross section perpendicular to the central axis O1, the pair of upper restraint surfaces 19 may have a pair of upper linear portions 19a each extending from the upper base surface 17, which is shown as a concave curve. The angle formed by the pair of upper linear portions 19a in this cross section may be defined as the upper opening angle θ0. Note that, when the upper base surface 17 is located between the pair of upper restraint surfaces 19, the upper opening angle θ0 may be evaluated by virtually extending and intersecting the upper linear portions 19a. The opening angle is also called a wedge angle.

[0015] 5, the first lower groove 15 has a first lower bottom surface 21 having a concave curved shape, and a pair of first lower restraint surfaces 23 extending downward from the first lower bottom surface 21. The pair of upper restraint surfaces 19 and the pair of first lower restraint surfaces 23 abut against the holder, thereby allowing the insert 1 to be stably restrained in the holder.

[0016] The opening angle of the first lower groove 15 in a cross section perpendicular to the central axis O1 may be the first opening angle θ1 (see FIG. 5 ). The first opening angle θ1 may also be referred to as the first lower opening angle θ1. For example, in a cross section perpendicular to the central axis O1, the pair of first lower restraint surfaces 23 may have a pair of first lower linear portions 23a extending from the first lower bottom surface 21, which is represented by a concave curved shape. The opening angle of the pair of first lower linear portions 23a in this cross section may be the first lower opening angle θ1. In other words, the angle formed by the pair of first lower linear portions 23a in this cross section may be the first lower opening angle θ1. Note that, when the first lower bottom surface 21 is located between the pair of first lower restraint surfaces 23, the first lower opening angle θ1 may be evaluated by virtually extending and intersecting the first lower linear portions 23a. The first lower bottom surface 21 may be the portion of the first lower groove 15 closest to the central axis O1.

[0017] The first cutting portion 5 may have a first end face 25, a second upper face 27, a second lower face 29, and a first cutting edge 31. The first end face 25 may be a surface located at the first end 1 a of the first cutting portion 5. Since the first cutting portion 5 is located on the side of the first end 1 a of the insert 1, it may be said that the first end face 25 is located at the first end 1 a of the insert 1.

[0018] The second upper surface 27 may be a surface located above the first cutting portion 5, and may extend from the first end surface 25 to the first upper surface 9. As shown in a non-limiting example in FIG. 2 , the second upper surface 27 may not have the upper groove 13 formed thereon for restraining the holder.

[0019] The second lower surface 29 may be a surface located below the first cutting portion 5, and may extend from the first end surface 25 to the first lower surface 11. The second lower surface 29 may also have a second lower groove 33 extending along the central axis O1. In a cross section perpendicular to the central axis O1, the second lower groove 33 may have a V-shape that opens downward, similar to the first lower groove 15.

[0020] 6 , the second lower groove 33 has a second lower bottom surface 35 having a concave curved shape and a pair of second lower restraining surfaces 37 extending downward from the second lower bottom surface 35. The second lower groove 33 may be used to restrain the insert 1 in the holder.

[0021] The opening angle of the second lower groove 33 in a cross section perpendicular to the central axis O1 may be the second opening angle θ2 (see FIG. 6 ). The second opening angle θ2 may also be referred to as the second lower opening angle θ2. For example, in a cross section perpendicular to the central axis O1, the pair of second lower restraint surfaces 37 may have a pair of second lower linear portions 37a extending from the second lower bottom surface 35, which is represented by a concave curved shape. The angle formed by the pair of second lower linear portions 37a in this cross section may be defined as the second lower opening angle θ2. Note that, if the second lower bottom surface 35 is located between the pair of second lower restraint surfaces 37, the second lower opening angle θ2 may be evaluated by virtually extending and intersecting the second lower linear portions 37a. The second lower bottom surface 35 may be the portion of the second lower groove 33 closest to the central axis O1.

[0022] The first cutting edge 31 may be a portion that plays a main role when cutting a workpiece, and may be located at the intersection of the first end face 25 and the second top face 27. The first cutting edge 31 may be located over the entire intersection of the first end face 25 and the second top face 27, or may be located over only a portion of the intersection of the first end face 25 and the second top face 27. When cutting using the first cutting edge 31, the second top face 27 may function as a rake face, and the first end face 25 may function as a flank face. The first cutting edge 31 is generally called a leading cutting edge or a main cutting edge.

[0023] The second cutting portion 7 may have a second end surface 39, a third upper surface 41, a third lower surface 43, and a second cutting edge 45. The second end surface 39 may be a surface located at the second end 1b of the second cutting portion 7. Since the second cutting portion 7 is located on the side of the second end 1b of the insert 1, it may be said that the second end surface 39 is located at the second end 1b of the insert 1.

[0024] The third upper surface 41 may be a surface located above the second cutting portion 7, and may extend from the second end surface 39 to the first upper surface 9. As shown in a non-limiting example in FIG. 2 , the third upper surface 41 does not need to have the upper groove 13 formed thereon for restraining the holder.

[0025] The third lower surface 43 may be a surface located below the second cutting portion 7, and may extend from the second end surface 39 to the first lower surface 11. The third lower surface 43 may also have a third lower groove 47 extending along the central axis O1. In a cross section perpendicular to the central axis O1, the third lower groove 47 may have a V-shape that opens downward, similar to the first lower groove 15.

[0026] 7 , the third lower groove 47 may have a third lower bottom surface 49 having a concave curved shape and a pair of third lower restraining surfaces 51 extending downward from the third lower bottom surface 49. The third lower groove 47 may be used to restrain the insert 1 in the holder.

[0027] The opening angle of the third lower groove 47 in a cross section perpendicular to the central axis O1 may be the third opening angle θ3 (see FIG. 7 ). The third opening angle θ3 may also be referred to as the third lower opening angle θ3. For example, in a cross section perpendicular to the central axis O1, the pair of third lower restraint surfaces 51 may have a pair of third lower linear portions 51a extending from the third lower bottom surface 49, which is represented by a concave curved shape. The angle formed by the pair of third lower linear portions 51a in this cross section may be defined as the third lower opening angle θ3. Note that, if the third lower bottom surface 49 is located between the pair of third lower restraint surfaces 51, the third lower opening angle θ3 may be evaluated by virtually extending and intersecting the third lower linear portions 51a. The third lower bottom surface 49 may be the portion of the third lower groove 47 closest to the central axis O1.

[0028] The second cutting edge 45 may be a portion that plays a primary role in cutting a workpiece, and may be located at the intersection of the second end face 39 and the third upper face 41. The second cutting edge 45 may be located over the entire intersection of the second end face 39 and the third upper face 41, or may be located over only a portion of the intersection of the second end face 39 and the third upper face 41. When cutting using the second cutting edge 45, the third upper face 41 may function as a rake face, and the second end face 39 may function as a flank face. The second cutting edge 45, like the first cutting edge 31, is generally called a leading cutting edge or a main cutting edge.

[0029] In the insert 1, the first downward opening angle θ1 may be larger than the second downward opening angle θ2 and the third downward opening angle θ3. In this case, it is possible to ensure high levels of both durability against the load applied to the insert 1 when held in the holder and stability of holding by the holder. This is for the following reason.

[0030] First, the first downward opening angle θ1 is relatively large, which provides high durability against the load applied when the cutting insert 1 is held in the holder. Second, the second downward opening angle θ2 in the first cutting portion 5 and the third downward opening angle θ3 in the second cutting portion 7 are relatively small, which makes it difficult for lateral displacement to occur directly below the cutting edge during cutting, regardless of whether the first cutting edge 31 or the second cutting edge 45 is used, and the cutting insert 1 is easily held stably by the holder.

[0031] The first downward opening angle θ1, the second downward opening angle θ2, and the third downward opening angle θ3 do not need to be limited to specific values ​​as long as they satisfy the above-mentioned relationships. For example, the first downward opening angle θ1 of the main body 3 may be set to 120° to 160°, the second downward opening angle θ2 of the first cutting portion 5 may be set to 100° to 140°, and the third downward opening angle θ3 of the second cutting portion 7 may be set to 100° to 140°. Furthermore, the upward opening angle θ0 of the main body 3 may be set to 120° to 160°.

[0032] 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 18 to 22 mm. Furthermore, the width of the insert 1 in the direction perpendicular to the central axis O1 when the first upper surface 9 of the main body 3 is viewed from the front may be set to approximately 2 to 6 mm. Furthermore, the height of the insert 1 in the direction perpendicular to the first upper surface 9 may be set to approximately 2 to 6 mm.

[0033] The first downward opening angle θ1, the second downward opening angle θ2, and the third downward opening angle θ3 may each be constant or may vary. In a non-limiting example shown in Figure 3, the first downward opening angle θ1, the second downward opening angle θ2, and the third downward opening angle θ3 are each constant in the direction along the central axis O1. In other words, the pair of first lower constraint surfaces 23, the pair of second lower constraint surfaces 37, and the pair of third lower constraint surfaces 51 each have a flat surface shape.

[0034] When the pair of first lower constraint surfaces 23 are flat, it is easy to suppress variations in durability against the clamping force of the holder. When the pair of second lower constraint surfaces 37 are flat, it is easy to suppress variations in durability against the cutting load applied when cutting is performed using the first cutting edge 31. Furthermore, when the pair of third lower constraint surfaces 51 are flat, it is easy to suppress variations in durability against the cutting load applied when cutting is performed using the second cutting edge 45.

[0035] In a cross section perpendicular to the central axis O1, the pair of first lower restraint surfaces 23 may each have another linear portion in addition to the first lower linear portions 23a. For example, as shown in a non-limiting example in FIG. 8 , in a cross section perpendicular to the central axis O1, the first lower groove 15 may further have, in addition to the bottom surface 21 (first lower bottom surface 21) and the pair of first linear portions 23a (first lower linear portions 23a), a pair of second linear portions 23b extending from the pair of first linear portions 23a and inclined with respect to the pair of first linear portions 23a. In a cross section perpendicular to the central axis O1, the length of the second linear portions 23b may be shorter than the length of the first linear portions 23a.

[0036] Here, in a cross section perpendicular to the central axis O1, the opening angle of the pair of second straight line portions 23b may be the fourth opening angle θ4 (fourth downward opening angle θ4). In other words, the angle formed by the pair of second straight line portions 23b in this cross section may be the fourth downward opening angle θ4. Note that the fourth downward opening angle θ4 may be evaluated by virtually extending and intersecting the second straight line portions 23b.

[0037] 8, the fourth downward opening angle θ4 may be smaller than the first downward opening angle θ1. When the first lower groove 15 has the above-described configuration, the effect of preventing lateral displacement of the main body 3 is enhanced while ensuring the effect of improving durability of the main body 3 against the clamping force of the holder.

[0038] Furthermore, the fourth lower opening angle θ4 may be smaller than the second lower opening angle θ2 and the third lower opening angle θ3. In this case, the insert 1 as a whole is more effective in preventing lateral slippage without making the second lower opening angle θ2 in the first cutting portion 5 and the third lower opening angle θ3 in the second cutting portion 7 extremely small. The fourth lower opening angle θ4 is not limited to a specific value and may be set to, for example, 90° to 150°.

[0039] The second lower surface 29 of the first cutting portion 5 may further have a slit 53 (first slit 53) located on the second end 1b side in addition to the second lower groove 33. In this case, the second lower groove 33 may be separated from the first lower groove 15 via the first slit 53.

[0040] When the second lower surface 29 has the first slit 53, the insert 1 can be easily and stably attached to the holder. This is because the first lower groove 15 and the second lower groove 33 can be easily and stably brought into contact with the holder even if the insert 1 is slightly misaligned with respect to the holder when attaching the insert 1 to the holder.

[0041] The first slits 53 may extend in a direction perpendicular to the central axis O1. More specifically, when the second lower surface 29 is viewed from the front, the first slits 53 may extend in a direction perpendicular to the central axis O1. In this case, even if the insert 1 is slightly misaligned with respect to the holder, the first lower groove 15 and the second lower groove 33 can more stably contact the holder.

[0042] Similarly, the third lower surface 43 of the second cutting portion 7 may further have a second slit 55 located on the side of the first end 1 a in addition to the third lower groove 47. In this case, the third lower groove 47 may be separated from the first lower groove 15 by the second slit 55.

[0043] When the third lower surface 43 has the second slit 55, the insert 1 can be easily and stably attached to the holder. This is because the first lower groove 15 and the third lower groove 47 can be easily and stably brought into contact with the holder even if the insert 1 is slightly misaligned with respect to the holder when attaching the insert 1 to the holder.

[0044] When the third lower surface 43 is viewed from the front, the second slit 55 may extend in a direction perpendicular to the central axis O1. In this case, even if the insert 1 is slightly misaligned with respect to the holder, the first lower groove 15 and the third lower groove 47 can be more stably brought into contact with the holder.

[0045] The insert 1 may be made of an inorganic material such as cemented carbide, cermet, or ceramic. The cemented carbide may have a composition such as WC (tungsten carbide)-Co, WC-TiC (titanium carbide)-Co, or WC-TiC-TaC (tantalum carbide)-Co. Here, WC, TiC, and TaC may be hard particles, and Co may be a binder phase.

[0046] The cermet may also be a sintered composite material in which a ceramic component is combined with a metal. Specifically, the cermet may be a compound mainly composed of TiC or TiN (titanium nitride). However, it goes without saying that the material of the insert 1 is not limited to these.

[0047] Although not shown, the insert 1 may have a main body (substrate) containing the above-mentioned material and a coating layer covering the main body. Examples of the material for the coating layer include titanium carbide, nitride, oxide, carbonate, oxynitride, carbonitride, and oxycarbonitride.

[0048] The coating layer may contain only one of the above materials, or may contain multiple materials. The coating layer may be composed of only one layer, or may be composed of multiple layers stacked together. The materials for the coating layer are not limited to these.

[0049] The coating layer may be disposed on the substrate by using chemical vapor deposition (CVD) or physical vapor deposition (PVD) techniques.

[0050] <Cutting Tool> Next, a non-limiting one-sided cutting tool 101 of the present disclosure will be described with reference to the drawings.

[0051] The cutting tool 101 may have a holder 103 and an insert 1. When the cutting tool 101 has the insert 1, it is possible to ensure high levels of both durability against a load applied to the insert 1 when it is held in the holder 103 and stability of holding by the holder 103, and therefore it is possible to exhibit excellent cutting performance.

[0052] The holder 103 may be rod-shaped. Furthermore, the holder 103 may be rod-shaped extending from a front end 103a (the lower left end in FIG. 9 ) to a rear end 103b (the upper right end in FIG. 9 ), as in a non-limiting example shown in FIG. 9 . The holder 103 may be rod-shaped extending from the front end 103a to the rear end 103b.

[0053] The holder 103 may also have a pocket 105 located at the tip 103 a. As a non-limiting example shown in Figures 9 and 10 , the holder 103 may have an upper jaw 107 and a lower jaw 109 located on the side of the tip 103 a and spaced apart from each other. The upper jaw 107 and the lower jaw 109 may form the pocket 105.

[0054] The insert 1 may be positioned within the pocket 105. In other words, the insert 1 may be sandwiched between the upper jaw 107 and the lower jaw 109. The insert 1 may be attached so that at least a part of the portion used as a cutting edge protrudes outward from the holder 103.

[0055] 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.

[0056] 9 shows a non-limiting example of a cutting tool 101 used for so-called turning. The cutting tool 101 can be used for grooving, but is not limited to such a process. For example, the cutting tool 101 may be used for internal diameter machining, external diameter machining, and traversing feed machining without any problem.

[0057] <Method for Manufacturing Machined Product> Next, a non-limiting method for manufacturing a machined product having one surface according to the present disclosure will be described with reference to the drawings.

[0058] 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, typified by the above-described embodiment, into contact with the rotating workpiece 203; and (3) a step of separating the cutting tool 101 from the workpiece 203.

[0059] More specifically, first, as in a non-limiting example shown in Fig. 11 , the workpiece 203 may be rotated around the axis O2, and the cutting tool 101 attached to the machine tool may be brought relatively close to the workpiece 203. Next, as in a non-limiting example shown in Fig. 12 , the cutting edge (first cutting edge 31 or second cutting edge 45) 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. 13 , the cutting tool 101 may be moved relatively away from the workpiece 203.

[0060] By going through the above steps, it is possible to obtain a machined product 201 with a highly accurate finished surface. Specifically, in the manufacturing method of the machined product 201, when the cutting tool 101 having the insert 1 is used, it is possible to ensure high levels of both durability against the load applied to the insert 1 when held in the holder 103 and stability of holding by the holder 103, and therefore it is possible to exhibit excellent workability. As a result, it is possible to obtain a machined product 201 with a highly accurate finished surface.

[0061] In a non-limiting example shown in Fig. 11, the axis O2 is fixed and the workpiece 203 is rotated around the axis O2, and the cutting tool 101 is moved in the Y1 direction to approach the workpiece 203. In a non-limiting example shown in Fig. 12, the cutting edge of the insert 1 is brought into contact with the rotating workpiece 203 to cut the workpiece 203. In a non-limiting example shown in Fig. 13, the cutting tool 101 is moved in the Y2 direction to move away from the rotating workpiece 203.

[0062] In the non-limiting example shown in Figures 11 to 13, in each process, the cutting tool 101 is moved to bring the cutting tool 101 into contact with the workpiece 203 or to move the cutting tool 101 away from the workpiece 203, but of course, this is not limited to this form.

[0063] For example, in step (1), the workpiece 203 may be brought closer to the cutting tool 101. Similarly, 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 edge of the insert 1 into contact with different locations on the workpiece 203 may be repeated.

[0064] Examples of the material of the workpiece 203 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0065] The above provides examples of the non-limiting one-sided insert 1, cutting tool 101, and method for manufacturing 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.

[0066] For example, the manufacturing method of the insert 1, the cutting tool 101, and the machined product 201 may be configured as follows: (1) The cutting insert has a rod shape extending from a first end toward a second end along a central axis, and includes a main body, a first cutting portion located closer to the first end than the main body, and a second cutting portion located closer to the second end than the main body, the main body having a first upper surface having an upper groove extending along the central axis, and a first lower surface located on the opposite side of the first upper surface and having a first lower groove extending along the central axis, the first cutting portion having a first end surface located at the first end, a second upper surface extending from the first end surface to the first upper surface, a second lower surface extending from the first end surface to the first lower surface and having a second lower groove extending along the central axis, and a first lower surface having a first end surface and a front end surface. (2) In the cutting insert of (1), the first opening angle, the second opening angle, and the third opening angle may be constant in a direction along the central axis. (3) In the cutting insert of (1) or (2), in a cross section perpendicular to the central axis, the first lower groove may have a concavely curved bottom surface, a pair of first linear portions each extending from the bottom surface, and a pair of second linear portions extending from the pair of first linear portions and inclined relative to the pair of first linear portions, wherein an opening angle between the pair of first linear portions is the first opening angle, and an opening angle between the pair of second linear portions is a fourth opening angle, and the fourth opening angle may be smaller than the first opening angle. (4) In the cutting insert of (3), the fourth opening angle may be smaller than the second opening angle and the third opening angle.(5) In the cutting insert of any one of (1) to (4) above, the second lower surface may further have a slit located on the side of the second end, and the second lower groove may be separated from the first lower groove via the slit. (6) In the cutting insert of (5) above, the slit may extend in a direction perpendicular to the central axis. (7) The cutting tool may have a rod-like shape extending from a front end to a rear end, the holder having a pocket located at the front end, and the cutting insert of any one of (1) to (6) above located in the pocket. (8) A method for manufacturing a machined product may include the steps of rotating a workpiece, bringing the cutting tool of (7) above into contact with the rotating workpiece, and separating the cutting tool from the workpiece.

[0067] 1... Cutting insert (insert) 1a... First end 1b... Second end 3... Main body part 5... First cutting part 7... Second cutting part 9... First upper surface 11... First lower surface 13... Upper groove 15... First lower groove 17... Upper bottom surface 19... Upper restraining surface 19a... Upper straight part 21... First lower bottom surface 23... First lower restraining surface 23a... First lower straight part (first straight part) 23b... Second straight part 25... First end surface 27... Second upper surface 29... Second lower surface 31... First cutting edge 33... Second lower groove 35... Second lower bottom surface 37... Second lower restraining surface 37a... Second lower straight part 39... Second end surface 41... Third upper surface 43... Third lower surface 45... Second cutting edge 47: Third lower groove 49: Third lower bottom surface 51: Third lower restraint surface 51a: Third lower straight portion 53: First slit 55: Second slit 101: Cutting tool 103: Holder 103a: Tip 103b: Rear end 105: Pocket 107: Upper jaw 109: Lower jaw 201: Cutting workpiece 203: Workpiece O1: Central axis

Claims

1. A rod shape extending from a first end to a second end along a central axis, a main body; a first cutting portion located closer to the first end than the main body portion; a second cutting portion located closer to the second end than the main body portion, The main body portion is a first upper surface having an upper groove extending along the central axis; a first lower surface located opposite the first upper surface and having a first lower groove extending along the central axis; The first cutting portion is a first end surface located at the first end; a second upper surface extending from the first end surface to the first upper surface; a second lower surface extending from the first end surface to the first lower surface and having a second lower groove extending along the central axis; a first cutting edge located at an intersection of the first end surface and the second upper surface, The second cutting portion is a second end surface located at the second end; a third upper surface extending from the second end surface to the first upper surface; a third lower surface extending from the second end surface to the first lower surface and having a third lower groove extending along the central axis; a second cutting edge located at an intersection of the second end surface and the third upper surface, an opening angle of the first lower groove in a cross section perpendicular to the central axis is a first opening angle, an opening angle of the second lower groove in a cross section perpendicular to the central axis is a second opening angle, and an opening angle of the third lower groove in a cross section perpendicular to the central axis is a third opening angle, The cutting insert, wherein the first opening angle is larger than the second opening angle and the third opening angle.

2. The cutting insert according to claim 1 , wherein the first opening angle, the second opening angle, and the third opening angle are each constant in a direction along the central axis.

3. In a cross section perpendicular to the central axis, The first lower groove is A bottom surface having a concave curved shape; a pair of first linear portions each extending from the bottom surface; a pair of second linear portions extending from the pair of first linear portions and inclined relative to the pair of first linear portions; an opening angle of the pair of first straight line portions is the first opening angle, an opening angle of the pair of second straight line portions is a fourth opening angle, The cutting insert according to claim 1 , wherein the fourth opening angle is smaller than the first opening angle.

4. The cutting insert according to claim 3 , wherein the fourth opening angle is smaller than the second opening angle and the third opening angle.

5. the second lower surface further has a slit located on the second end side; The cutting insert according to claim 1 , wherein the second lower groove is separated from the first lower groove via the slit.

6. The cutting insert according to claim 5 , wherein the slit extends in a direction perpendicular to the central axis.

7. a holder having a rod shape extending from a front end to a rear end and having a pocket located at the front end; and the cutting insert according to any one of claims 1 to 6, located in the pocket.

8. rotating the workpiece; bringing the cutting tool according to claim 7 into contact with the rotating workpiece; and removing the cutting tool from the workpiece.