Holder, cutting tool, and production method of cut object

Abstract

To provide a cutting tool which can detect a cutting load with high precision.SOLUTION: A holder has a body extending along a center axis from a first end to a second end and a first strain sensor. The body has a first end surface, an upper surface, a lower surface, a first outer surface, a second outer surface, a pocket which is located at the side of the first end and on which a cutting insert may be mounted; and a recessed part located at the side of the first end. The first strain sensor is installed in the recessed part. The recessed part has a first inner surface which is located closer to the second end than the first end surface and orthogonal to the center axis. The first strain sensor is located on the first inner surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] As a cutting tool used in cutting a workpiece to manufacture a machined product, for example, there is known a cutting tool described in Patent Document 1. The cutting tool described in Patent Document 1 has a rod-shaped holder to which a detector is attached. The holder has a long groove, and the long groove has a bottom surface extending along the central axis of the holder, and the detector is attached to this bottom surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 57-079431 Summary of the Invention [Problem to be solved by the invention]

[0004] In cutting processing, a cutting load is applied to the cutting tool. The cutting load can be divided into three components: a principal force, a thrust force, and a feed force. Generally, of these components, the principal force is the largest, followed by the feed force. The detector in the cutting tool described in Patent Document 1 can detect the thrust force and the feed force, but has difficulty detecting the principal force. Therefore, the detection accuracy of the cutting load is insufficient, and a cutting tool capable of detecting the cutting load with higher accuracy has been demanded.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a cutting tool capable of detecting cutting load with high accuracy. [Means for solving the problem]

[0006] A holder according to a non-limiting embodiment of the present disclosure has a main body extending along a central axis from a first end to a second end, and a first strain sensor having a flat plate shape. The main body has a first end face located on the first end side, an upper face extending from the first end face toward the second end, a lower face located opposite the upper face, a first outer side face connected to the upper face, the lower face, and the first end face, a second outer side face located opposite the first outer side face and connected to the upper face, the lower face, and the first end face, a pocket located on the first end side, opening on the upper face and the first outer side face, and capable of mounting a cutting insert, and a recess located on the first end side and opening on the lower face and the second outer side face. The first strain sensor is installed in the recess. The recess has a first inner side face located closer to the second end than the first end face and perpendicular to the central axis, and the first strain sensor is located on the first inner side face. Effect of the Invention

[0007] A holder according to an aspect of the present disclosure is capable of detecting cutting load with high accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view of a non-limiting one-sided cutting tool of the present disclosure. [Diagram 2] 2 is a schematic perspective view of the cutting tool shown in FIG. 1 as viewed from a different angle. [Diagram 3] FIG. 2 is a schematic top view of the cutting tool shown in FIG. [Figure 4] FIG. 2 is a schematic front view of the cutting tool shown in FIG. 1 as viewed from the tip side. [Diagram 5] 3 is a schematic enlarged view of a region V in the cutting tool shown in FIG. 2. FIG. [Figure 6] 6 is a schematic enlarged view of a cutting tool according to another embodiment of the present disclosure, in which a region corresponding to that in FIG. 5 is enlarged. [Figure 7] 1A to 1C are schematic diagrams illustrating a manufacturing method of a machined product according to an embodiment of the present disclosure. [Figure 8] 1A to 1C are schematic diagrams illustrating a manufacturing method of a machined product according to an embodiment of the present disclosure. [Figure 9]1A to 1C are schematic diagrams illustrating a manufacturing method of a machined product according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the holder 10, cutting tool 12, and manufacturing method of machined product according to the embodiment of the present disclosure will be described in detail with reference to the drawings. However, for the convenience of explanation, each of the drawings referred to below shows only the components necessary for explaining the embodiment in a simplified manner. Therefore, the holder 10 according to the embodiment of the present disclosure may include any components not shown in each of the drawings referred to. The dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components and the dimensional ratios of each member.

[0010] In addition, in each of the drawings to be referred to, an orthogonal coordinate system XYZ defined by three mutually orthogonal directions is shown, and in the present disclosure, the holder 10 according to the embodiment and the like are described based on the orthogonal coordinate system XYZ. The X direction refers to the front-rear direction of the holder 10 or the cutting tool 12 (hereinafter, the object), one side of the X direction is the front side or the front direction of the object, and the other side of the X direction is the rear side or the rear direction of the object. The Y direction refers to the left-right direction of the object, one side of the Y direction is the left side or the left direction of the object, and the other side of the Y direction is the right side or the right direction of the object. The Z direction refers to the up-down direction of the object, one side of the Z direction is the upper side or the upward direction of the object, and the other side of the Z direction is the lower side or the downward direction of the object.

[0011] The XY direction refers to the two directions, X and Y, the XZ direction refers to the two directions, X and Z, and the YZ direction refers to the two directions, Y and Z. The XYZ direction refers to the three directions, X, Y, and Z. In the drawings, "FF" refers to the front direction, "FR" refers to the rear direction, "L" refers to the left direction, "R" refers to the right direction, "U" refers to the up direction, and "D" refers to the down direction.

[0012] However, the description based on the Cartesian coordinate system XYZ in this disclosure is provided for the purpose of facilitating understanding of the structure of the holder 10. Therefore, the description based on the Cartesian coordinate system XYZ above does not limit the use state of the cutting tool 12 during cutting processing.

[0013] <Cutting tools> A cutting tool 12 according to an embodiment of the present disclosure will be described with reference to Figures 1 to 5. The cutting tool 12 according to the embodiment of the present disclosure can be used for cutting a workpiece W (see Figure 7). The cutting of the workpiece includes external diameter machining, internal diameter machining, grooving, cut-off machining, and the like.

[0014] The cutting tool 12 has a holder 10 and a cutting insert 14. The cutting insert 14 is a member that can be used to cut a workpiece, and the holder 10 is a member that can be used to hold the cutting insert 14. The cutting insert 14 can be attached to the holder 10, and the holder 10 can be attached to a machine tool. For example, the holder 10 can be attached to a tool rest of a lathe.

[0015] As a non-limiting example shown in Fig. 1, the cutting tool 12 may further include a clamp 16 and a screw 18. The cutting insert 14 may be fixed to the holder 10 by clamping the cutting insert 14 with the clamp 16 and the holder 10 and fixing the clamp 16 to the holder 10 with the screw 18. Note that the attachment of the cutting insert 14 to the holder 10 is not limited to the configuration using the clamp 16 and the screw 18 shown in Fig. 1.

[0016] <Holder> As shown in the example in Fig. 1 to Fig. 4, the holder 10 may have a main body 20 having, for example, a rectangular prism shape extending along a central axis O1 from a first end (front end) 20a to a second end (rear end) 20b. The central axis O1 is an axis along the longitudinal direction of the main body 20. The central axis O1 may be, for example, an axis passing through the center of gravity of the main body 20 when viewed from the second end 20b side. The central axis O1 may be an axis passing through the center of at least one of a first end face (front end face) 22 on the first end 20a side of the main body 20 or a second end face (rear end face) 24 on the second end 20b side.

[0017] 1 to 4, the central axis O1 may extend along the X direction. The longitudinal direction of the main body 20 may be the X direction. When attaching the holder 10 to a machine tool, the portion of the main body 20 on the side of the second end 20b may be fixed to the machine tool.

[0018] In the holder 10 in one example, the main body 20 in the shape of a rectangular prism may have a first end face 22, a second end face 24, an upper face 26, a lower face 28, a first outer side face 30, and a second outer side face 32. The first end face 22 may be located on the side of the first end 20a of the main body 20, and the second end face 24 may be located on the side of the second end 20b of the main body 20. The upper face 26, the lower face 28, the first outer side face 30, and the second outer side face 32 may each extend from the first end face 22 toward the second end 20b.

[0019] 1 and 2, the upper surface 26, the lower surface 28, the first outer surface 30, and the second outer surface 32 may each extend from the first end surface 22 to the second end surface 24. In other words, the upper surface 26, the lower surface 28, the first outer surface 30, and the second outer surface 32 each extend in the X direction.

[0020] 4, the upper surface 26 may be located at one end in the Z direction, and the lower surface 28 may be located at the other end in the Z direction. In other words, the lower surface 28 may be located opposite the upper surface 26.

[0021] 4, the first outer surface 30 may be located at one end in the Y direction, and the second outer surface 32 may be located at the other end in the Y direction. In other words, the second outer surface 32 may be located opposite the first outer surface 30. The first outer surface 30 and the second outer surface 32 may be connected to the upper surface 26, the lower surface 28, the first end surface 22, and the second end surface 24, respectively.

[0022] The first end face 22, the second end face 24, the upper face 26, the lower face 28, the first outer side face 30, and the second outer side face 32 may each be formed by a single flat surface, but the specific shape of the main body 20 is not limited to such a configuration. As an example shown in Figures 1 to 4, each face may have a slight step.

[0023] In general, a portion of the main body 20 located on the second end 20b side, in which the upper surface 26, the lower surface 28, the first outer surface 30, and the second outer surface 32 are each formed as a single plane, is called a "shank." Also, a portion located on the first end 20a side of the shank and having a width in the Y direction slightly larger than that of the shank is called a "head." In the example shown in Figures 1 to 4, the main body 20 includes a shank 20S and a head 20H.

[0024] 3, the upper surface 26 and the lower surface 28 may be perpendicular to the first end surface 22 and the second end surface 24, respectively. The shank 20S may have a shape in which the upper surface 26, the lower surface 28, and the second end surface 24 are perpendicular to the first outer surface 30 and the second outer surface 32, respectively. In the holder 10 in the example, the main body 20 may have the first end surface 22, the second end surface 24, the upper surface 26, and the lower surface 28 perpendicular to the first outer surface 30 and the second outer surface 32, respectively.

[0025] The size of the main body 20 is not limited to a specific size. The length in the X direction (the distance between the first end face 22 and the second end face 24) may be set to, for example, 100 mm to 400 mm. The length in the Y direction (the distance between the first outer side face 30 and the second outer side face 32) may be set to, for example, 20 mm to 50 mm. The length in the Z direction (the distance between the upper face 26 and the lower face 28) may be set to, for example, 20 mm to 50 mm. Examples of materials for the main body 20 include metals such as stainless steel, carbon steel, cast iron, and aluminum alloy.

[0026] As shown in an example in Fig. 2, the main body 20 may have a pocket 34. The pocket 34 is a concave portion located on the first end 20a side of the main body 20, and may open to the upper surface 26 and the first outer side surface 30. As shown in an example in Fig. 2, the pocket 34 may also open to the first end surface 22. The pocket 34 is a portion to which the cutting insert 14 is fixed, and the cutting insert 14 can be mounted. When cutting is performed using the cutting insert 14 mounted in the pocket 34, a thrust force is usually applied in the X direction, a feed force is applied in the Y direction, and a principal force is applied in the Z direction.

[0027] 2 may have a recess 36 located on the first end 20a side, in addition to the pocket 34. The recess 36 may open to the lower surface 28 and the second outer surface 32. As in the example shown in FIG. 2, the recess 36 may also open to the first end surface 22.

[0028] The holder 10 in this embodiment may have a first strain sensor 38 in addition to the main body 20. The first strain sensor 38 may be installed in the recess 36. The first strain sensor 38 has a flat plate shape, and is used to detect distortion when the main body 20 is distorted by a cutting load generated in cutting processing. Specifically, it is possible to detect distortion in the extending direction of the surface on which the first strain sensor 38 is attached.

[0029] The recess 36 may have a first inner side surface 40 perpendicular to the central axis O1. In other words, the first inner side surface 40 in the example shown in FIG. 4 and FIG. 5 is a surface extending in the YZ direction. The first inner side surface 40 may be located closer to the second end 20b than the first end face 22 and perpendicular to the central axis O1. The first inner side surface 40 does not need to be strictly perpendicular to the central axis O1, and even if the first inner side surface 40 is slightly inclined (specifically, about 5°) with respect to the central axis O1, the first inner side surface 40 may be considered to be perpendicular to the central axis O1. In other words, in the present disclosure, "perpendicular" is a concept that includes not only strict perpendicularity but also substantial perpendicularity (approximately perpendicular) within a certain error range (specifically, about 5°).

[0030] 5 may have a second inner side surface 42 and a third inner side surface 44 in addition to the first inner side surface 40. The second inner side surface 42 may be said to be a surface parallel to the upper surface 26 and extending in the XY direction. The second inner side surface 42 may be parallel to the upper surface 26 of the shank 20S in the main body 20. As with the first inner side surface 40, the second inner side surface 42 does not need to be strictly parallel to the upper surface 26, and even if the second inner side surface 42 is slightly inclined (specifically, about 5°) relative to the upper surface 26, the second inner side surface 42 may be considered to be parallel to the upper surface 26. In other words, in the present disclosure, "parallel" is a concept that includes not only strict parallelism but also substantial parallelism (approximately parallelism) within a certain error range (specifically, about 5°).

[0031] In other words, the third inner surface 44 is parallel to the first outer surface 30 and may be a surface extending in the XZ direction. The third inner surface 44 may be parallel to the first outer surface 30 of the shank 20S in the main body 20, or may be parallel to the second outer surface 32 of the shank 20S. The third inner surface 44 also does not need to be strictly parallel to the first outer surface 30, and even if the third inner surface 44 is slightly inclined (specifically, about 5°) relative to the first outer surface 30, the third inner surface 44 may be considered to be parallel to the first outer surface 30.

[0032] The first strain sensor 38 in the present disclosure may be located on the first inner surface 40. As described above, the first inner surface 40 is a surface extending in the YZ direction, and a feed component force is applied in the Y direction and a principal component force is applied in the Z direction. Therefore, the relatively large feed component force and principal component force can be efficiently detected. As a result, a cutting tool 12 capable of detecting cutting load with high accuracy can be provided.

[0033] The first strain sensor 38 may be a capacitance detection sensor or a piezoresistance sensor. If the first strain sensor 38 is a capacitance detection sensor, the sensor may be a MEMS (Micro Electro Mechanical Systems).

[0034] The holder 10 may have one or more first strain sensors 38. That is, as in an example shown in Fig. 6, a plurality of first strain sensors 38 may be located on the first inner surface 40. When the holder 10 has a plurality of first strain sensors 38, it is possible to improve the detection accuracy of the feed component force and the main component force.

[0035] There are no particular limitations on the specific method for feeding power to the first strain sensor 38 and for transmitting (inputting) the physical quantity (data) detected by the first strain sensor 38 to an external device (e.g., an information processing device), and any known method can be used as appropriate. For example, a wiring (not shown) may be electrically connected to the first strain sensor 38, and power may be fed to the first strain sensor 38 via the wiring. Alternatively, the first strain sensor 38 may be incorporated in an electric circuit including a battery, and power may be fed to the first strain sensor 38 from the battery. Also, for example, a power feeding device of a wireless power feeding system may be provided in the main body 20, the first strain sensor 38 may be installed near the power feeding device, and power may be fed to the first strain sensor 38 by non-contact power feeding.

[0036] The physical quantity detected by the first strain sensor 38 may be transmitted to an external device by wire via wiring (not shown), or may be transmitted to an external device wirelessly using a wireless communication unit (not shown). The wireless communication unit may be built into the first strain sensor 38, or the wireless communication unit and the first strain sensor 38 may be provided separately.

[0037] The wiring may be routed, for example, through a passage (not shown) formed inside the main body 20, or may be routed along the side surface of the main body 20. The side surface of the main body 20 may be provided with a recess in which the wiring can be disposed.

[0038] The above description regarding the power supply to the first strain sensor 38 and the data transmission from the first strain sensor 38 also applies to the other strain sensors described below, and therefore repeated description will be omitted.

[0039] <Cutting insert> As shown in the example of FIG. 1 to FIG. 5, the cutting insert 14 may be located in the pocket 34 of the holder 10. The cutting insert 14 may be a replaceable insert called a throw-away insert. The cutting insert 14 may have a rectangular plate shape, or may have a triangular plate shape or a pentagonal plate shape other than the rectangular plate shape. The cutting insert 14 may have a first insert surface 46, a second insert surface 48 located on the opposite side of the first insert surface 46, and a plurality of insert side surfaces 50 located between the first insert surface 46 and the second insert surface 48. The first insert surface 46 may be located on the clamp 16 side.

[0040] The cutting insert 14 may have a cutting edge 52 at the intersection of the first insert surface 46 and the insert side surface 50. The first insert surface 46 may function as a rake surface for channeling chips. The insert side surface 50 may function as a clearance surface. In the example shown in FIG. 1, the first insert surface 46 of the cutting insert 14 faces in approximately the same direction as the top surface 26 of the body 20 of the holder 10. Therefore, the principal force is applied in the Z direction.

[0041] The cutting insert 14 may have a through hole 54 that opens to the first insert surface 46 and the second insert surface 48. The cutting insert 14 may be attached to the pocket 34 by tightening the screw 18 with the tip of the clamp 16 engaged with the through hole 54.

[0042] Examples of the material of the cutting insert 14 include cemented carbide and cermet. Examples of the composition of cemented carbide 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. The cermet is a sintered composite material in which a ceramic component is combined with a metal. Specifically, examples of the cermet include those mainly composed of titanium compounds such as titanium carbide (TiC) and titanium nitride (TiN).

[0043] A coating may be applied to the surface of the cutting insert 14 using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method. Examples of the material of the coating include titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and alumina (Al2O3).

[0044] <Configuration example> In the holder 10 in one example, the recess 36 may be located away from directly below the pocket 34. In other words, the entire recess 36 may be located closer to the second outer side surface 32 than the entire pocket 34, or the entire recess 36 may be located closer to the second end 20b than the entire pocket 34. The recess 36 may be open to the lower surface 28 and the second outer side surface 32, but not open to the first end surface 22. The recess 36 may be open to the second outer side surface 32, but not open to the lower surface 28 and the first end surface 22.

[0045] As described above, since the principal force is applied in the Z direction, the principal force is likely to be transmitted directly below the pocket 34 in which the cutting insert 14 is mounted. When the recess 36 is away from the area directly below the pocket 34, the thickness of the main body 20 in the area where the principal force is likely to be transmitted is likely to be ensured. Therefore, the effect of a decrease in durability of the main body 20 due to the main body 20 having the recess 36 is likely to be suppressed.

[0046] Furthermore, when the portion of the main body 20 on the side of the second end 20b is fixed to a machine tool as described above, the principal force applied directly below the pocket 34 in which the cutting insert 14 is mounted is transmitted to the second end 20b of the main body 20 and received by the machine tool. For this reason, it is better for the entire recess 36 to be located closer to the second outer surface 32 than the entire pocket 34, rather than the entire recess 36 being located closer to the second end 20b than the entire pocket 34. This is because it is easy to avoid the recess 36 being located on the path along which the principal force applied directly below the pocket 34 is transmitted to the second end 20b of the main body 20, and therefore the effect of the reduction in durability of the main body 20 due to the main body 20 having the recess 36 is easily suppressed.

[0047] In the holder 10 in one example, the first strain sensor 38 may be located closer to the second end 20b than the pocket 34 (see, for example, FIG. 3). In this case, the strain of the body 20 caused by the principal force applied directly below the pocket 34 can be measured with high accuracy. As described above, the principal force applied directly below the pocket 34 in which the cutting insert 14 is mounted is transmitted to the second end 20b of the body 20 and received by the machine tool. When the principal force applied directly below the pocket 34 in which the cutting insert 14 is mounted is transmitted to the second end 20b of the body 20, the body 20 is likely to bend significantly between the pocket 34 in the body 20 and the part fixed to the machine tool. Therefore, when the first strain sensor 38 is located as described above, the deflection of the body 20 is easily detected, and the strain of the body 20 can be measured with high accuracy.

[0048] The holder 10 in one example may further include a second strain sensor 56 in addition to the first strain sensor 38. The second strain sensor 56 may be installed in the recess 36. The second strain sensor 56 has a flat plate shape, and is used to detect distortion of the main body 20 when the main body 20 is distorted by a cutting load generated in the cutting process, similar to the first strain sensor 38. In this case, the second strain sensor 56 may be located on the second inner surface 42. As described above, the second inner surface 42 may be a surface extending in the XY direction, and a thrust force is applied in the X direction and a feed force is applied in the Y direction.

[0049] Generally, the principal force is very large compared to the feed force and the thrust force. Therefore, while the first strain sensor 38 can measure the principal force with high accuracy, there is a risk that information about the feed force is hidden by information about the principal force, making it difficult to improve the measurement accuracy of the feed force. However, when the holder 10 has the second strain sensor 56, the second strain sensor 56 can measure the feed force and the thrust force with high accuracy while suppressing the influence of the principal force. Therefore, the first strain sensor 38 and the second strain sensor 56 can measure all of the principal force, the feed force, and the thrust force with high accuracy.

[0050] The holder 10 may have one or more second strain sensors 56. That is, as in an example shown in Fig. 6, a plurality of second strain sensors 56 may be located on the second inner surface 42. When the holder 10 has a plurality of second strain sensors 56, the detection accuracy of the feed force and the thrust force can be improved.

[0051] When the holder 10 has a plurality of second strain sensors 56, the plurality of second strain sensors 56 may be arranged in a direction along the central axis O1, i.e., in the X direction, as in the example shown in Fig. 6. As described above, the main body 20 is likely to bend significantly between the pocket 34 in the main body 20 and the portion fixed to the machine tool. Therefore, the amount of strain of the main body 20 is likely to change in the X direction, and the amount of strain of the second strain sensor 56 is likely to change.

[0052] When multiple second strain sensors 56 are lined up in the X direction, it is easy to calculate the change in the amount of strain of the main body 20 in the X direction. Therefore, it is possible to reduce the influence of measurement errors and further improve the detection accuracy of the thrust force. In addition, although torque (twist) may be applied to the holder 10 during cutting, when multiple second strain sensors 56 are lined up in the X direction, it is possible to remove the above-mentioned torque component by using the multiple second strain sensors 56.

[0053] In the case where the holder 10 has the second strain sensor 56, the first inner surface 40 may be perpendicular to the second inner surface 42. When these surfaces are perpendicular to each other, the first strain sensor 38 and the second strain sensor 56 are disposed at positions perpendicular to each other. This makes it easier to separate the measurement data related to the main force, feed force, and thrust force detected by the first strain sensor 38 and the second strain sensor 56, and makes it possible to detect the cutting load with high accuracy.

[0054] The holder 10 in one example may further include a third strain sensor 58 in addition to the first strain sensor 38. The third strain sensor 58 may be installed in the recess 36. The third strain sensor 58 has a flat plate shape, and, like the first strain sensor 38, is used to detect distortion of the main body 20 when the main body 20 is distorted by a cutting load generated in the cutting process. In this case, the third strain sensor 58 may be located on the third inner side surface 44.

[0055] As described above, the third inner surface 44 is a surface extending in the XZ direction, and a thrust force is applied in the X direction, and a principal force is applied in the Z direction. The first strain sensor 38 measures the principal force and feed force, and the third strain sensor 58 measures the principal force and thrust force. Therefore, it is possible to measure three components of force, the principal force, the feed force, and the thrust force, and further, it is possible to detect the principal force from two directions. For these reasons, it is possible to detect the cutting load with high accuracy.

[0056] In the case where the holder 10 has the third strain sensor 58, the third inner surface 44 may be perpendicular to the first inner surface 40 and the second inner surface 42. When these surfaces are perpendicular to each other, the first strain sensor 38, the second strain sensor 56, and the third strain sensor 58 are disposed at perpendicular positions. This makes it easier to separate the measurement data related to the main force, feed force, and thrust force detected by the first strain sensor 38, the second strain sensor 56, and the third strain sensor 58, and makes it possible to detect the cutting load with high accuracy.

[0057] In one example of the holder 10, when the recess 36 has a first inner surface 40, a second inner surface 42, and a third inner surface 44, the area of ​​the first inner surface 40 may be smaller than the area of ​​the second inner surface 42, and the area of ​​the third inner surface 44 may be larger than the area of ​​the second inner surface 42.

[0058] As described above, the holder 10 is prone to large deflection of the main body 20 between the pocket 34 in the main body 20 and the portion fixed to the machine tool. Here, when the area of ​​the first inner side 40 is smaller than the areas of the second inner side 42 and the third inner side 44, the effect of the decrease in durability of the main body 20 due to the main body 20 having the recess 36 is easily suppressed. Also, when the area of ​​the third inner side 44 is larger than the area of ​​the second inner side 42, in other words, when the area of ​​the second inner side 42 is smaller than the area of ​​the third inner side 44, it is easy to position the recess 36 away from directly below the pocket 34. Therefore, the effect of the decrease in durability of the main body 20 due to the main body 20 having the recess 36 is even more easily suppressed.

[0059] <Method of manufacturing machined products> A method for manufacturing a machined product according to an embodiment of the present disclosure will be described with reference to Fig. 7 to Fig. 9. Fig. 7 to Fig. 9 are schematic views for explaining the method for manufacturing a machined product according to an embodiment of the present disclosure.

[0060] As shown in the examples of Figures 7 to 9, the manufacturing method of a machined product according to an embodiment of the present disclosure is a method for manufacturing a machined product M, which is a workpiece W that has been machined, and includes a first step, a second step, and a third step.

[0061] The first step is a step of rotating the workpiece W around its axis S. The second step is a step of contacting the cutting insert 14 of the cutting tool 12 with the rotating workpiece W to cut the workpiece W. The third step is a step of separating the cutting tool 12 from the cut workpiece W. Examples of the material of the workpiece W include stainless steel, carbon steel, alloy steel, cast iron, and non-ferrous metals. The specific contents of the manufacturing method of the machined product according to the embodiment are as follows.

[0062] First, the cutting tool 12 is attached to a tool rest, and the workpiece W is attached to the chuck of a lathe. Next, as shown in the example of Fig. 7, the chuck is rotated to rotate the workpiece W around its axis S (first step). Then, as shown in the example of Fig. 8, the cutting tool 12 is moved in the direction of arrow D1 to approach the workpiece W, and the cutting insert 14 is brought into contact with the rotating workpiece W to cut the workpiece W (second step). This allows a machined surface Wf to be formed on the workpiece W.

[0063] 9, the cutting tool 12 is moved in the direction of the arrow D2 to separate the cutting tool 12 from the workpiece W (third step). This completes the cutting of the workpiece W, and a machined product M can be produced, which is the workpiece W that has been machined. Since the cutting tool 12 can detect the cutting load with high accuracy for the reasons described above, the machined product M can be produced stably.

[0064] When cutting is continued, the cutting insert 14 may be repeatedly brought into contact with different locations of the workpiece W while rotating the workpiece W. In the embodiment of the present disclosure, the cutting tool 12 is brought close to the workpiece W, but since it is only necessary that the cutting tool 12 and the workpiece W are brought relatively close to each other, the workpiece W may be brought close to the cutting tool 12. In this regard, the cutting tool 12 may be moved away from the workpiece W in the same manner.

[0065] In one embodiment, (1) the holder has a main body extending from a first end to a second end along a central axis, and a first strain sensor having a flat plate shape. The main body has a first end face located on the first end side, an upper face extending from the first end face toward the second end, a lower face located opposite the upper face, a first outer side face connected to the upper face, the lower face, and the first end face, a second outer side face located opposite the first outer side face and connected to the upper face, the lower face, and the first end face, a pocket located on the first end side, opening on the upper face and the first outer side face, and capable of mounting a cutting insert, and a recess located on the first end side, opening on the lower face and the second outer side face. The first strain sensor is installed in the recess. The recess has a first inner side face located closer to the second end than the first end face and perpendicular to the central axis, and the first strain sensor is located on the first inner side face.

[0066] (2): In the holder of (1), the recess may be spaced apart from directly below the pocket.

[0067] (3): In the holder of (1) or (2), the first strain sensor may be located closer to the second end than the pocket.

[0068] (4): In any one of the holders (1) to (3), a second flat-plate-shaped strain sensor may be installed in the recess, the recess may further have a second inner surface parallel to the top surface, and the second strain sensor may be located on the second inner surface.

[0069] (5): The holder of (4) may include a plurality of the second strain sensors.

[0070] (6): In the holder of (5), the second strain sensors may be aligned in a direction along the central axis.

[0071] (7): In the holder of any one of (4) to (6), the first inner surface may be perpendicular to the second inner surface.

[0072] (8): In any one of the holders (1) to (7), the holder may further include a third flat-plate-shaped strain sensor installed in the recess, the recess further including a third inner surface parallel to the first outer surface, and the third strain sensor may be located on the third inner surface.

[0073] (9): In the holder of (8), the third inner surface may be perpendicular to the first inner surface and the second inner surface.

[0074] (10): In any one of the holders (1) to (9), the recess may further have a second inner side surface parallel to the upper surface and a third inner side surface parallel to the first outer surface, and the area of ​​the first inner side surface may be smaller than the area of ​​the second inner side surface, and the area of ​​the third inner side surface may be larger than the area of ​​the second inner side surface.

[0075] (11): The cutting tool may have the holder according to any one of (1) to (9) above, and a cutting insert located in the pocket.

[0076] (12) A method for manufacturing a machined product may include the steps of rotating a workpiece, bringing the cutting tool described in claim 11 into contact with the rotating workpiece, and removing the cutting tool from the workpiece.

[0077] [Additional notes] 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-mentioned 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 the embodiments obtained by appropriately combining the technical means disclosed in the 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]

[0078] 10 Holder 12 Cutting tools 14 Cutting insert 16 Clamp 18 Screws 20 Main unit 22 First end surface 24 Second end face 26 Top side 28 Bottom side 30 1st outer surface 32 Second outer surface 34 Pockets 36 Recess 38 First strain sensor 40 1st inner surface 42 Second inner surface 44 Third inner surface 46 First insert surface 48 Second insert surface 50 Insert side 52 Cutting edge 54 Through hole 56 Second strain sensor 58 3rd strain sensor

Claims

1. The device has a shape extending along a central axis from a first end to a second end, a first end surface located on the first end side; an upper surface extending from the first end surface toward the second end surface; a lower surface opposite the upper surface; a first outer surface connected to the upper surface, the lower surface, and the first end surface; a second outer surface opposite the first outer surface and connected to the top surface, the bottom surface, and the first end surface; A pocket located on the first end side, opening to the upper surface and the first outer surface, and capable of mounting a cutting insert; a recess located on the first end side and opening to the lower surface and the second outer surface; a body having A first strain sensor having a flat plate shape and installed in the recess; having the recess is located closer to the second end than the first end face and has a first inner side surface perpendicular to the central axis; The first strain sensor is located on the first inner surface of a holder.

2. The holder of claim 1 , wherein the recess is spaced apart from directly beneath the pocket.

3. The holder of claim 1 , wherein the first strain sensor is located closer to the second end than the pocket.

4. The sensor further includes a second strain sensor having a flat plate shape and disposed in the recess, The recess further has a second inner side surface parallel to the upper surface, The holder of claim 1 , wherein the second strain sensor is located on the second interior surface.

5. The holder according to claim 4 , comprising a plurality of the second strain sensors.

6. The holder according to claim 5 , wherein the second strain sensors are aligned in a direction along the central axis.

7. The holder of claim 4 , wherein the first inner surface is perpendicular to the second inner surface.

8. The sensor further includes a third strain sensor having a flat plate shape and disposed in the recess, The recess further has a third inner side surface parallel to the first outer side surface, The holder of claim 4 , wherein the third strain sensor is located on the third inner surface.

9. The holder of claim 8 , wherein the third inner surface is orthogonal to the first inner surface and the second inner surface.

10. The recessed portion is A second inner surface parallel to the top surface; a third inner surface parallel to the first outer surface, The holder of claim 1 , wherein an area of ​​the first inner side surface is smaller than an area of ​​the second inner side surface, and an area of ​​the third inner side surface is larger than an area of ​​the second inner side surface.

11. A holder according to any one of claims 1 to 10; a cutting insert located in the pocket.

12. Rotating the workpiece; contacting the rotating workpiece with the cutting tool according to claim 11; and removing the cutting tool from the workpiece.

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