Cutting Tools and Modules

Abstract

Accurately measure the distortion of cutting tools caused by cutting. [Solution] The cutting tool has a shaft portion, which includes an enlarged diameter portion having a larger diameter than other portions of the shaft portion, and the enlarged diameter portion has a recess formed on the circumferential surface of the enlarged diameter portion.

Description

[Technical field]

[0001] The present disclosure relates to cutting tools, modules, cutting tool units and cutting systems. This application claims priority based on Japanese Patent Application No. 2019-160746, filed on September 3, 2019, the disclosure of which is incorporated herein in its entirety. [Background technology]

[0002] Patent Document 1 (JP Patent Publication 2010-105095A) discloses the following cutting tool: That is, the cutting tool has a cutting edge at the tip of a main body, and further has a head piece with a chip groove on the outer periphery of the main body from a position along the cutting edge to the back surface of the main body, and the head piece is connected to the tip of a hollow shaft through which an airflow for discharging chips passes, in a chip-collecting cutting tool, the head piece is provided with a step portion that changes the outer diameter of the rear part of the main body and a small diameter portion that is located behind the step portion, the small diameter portion is fitted into a through hole on the tip side of the hollow shaft, and further, the step portion is abutted against the tip of the hollow shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-105095 A Summary of the Invention

[0004] The cutting tool of the present disclosure comprises a shaft portion including an enlarged diameter portion having a larger diameter than other portions of the shaft portion, the enlarged diameter portion having a recess formed in a peripheral surface of the enlarged diameter portion.

[0005] The cutting tool of the present disclosure includes a shaft portion, the shaft portion including a recess formed on a circumferential surface of the shaft portion, and a sensor attachment portion provided near the recess and capable of attaching a strain sensor.

[0006] The module of the present disclosure is a module that can be attached to a shaft portion of a cutting tool having a shaft portion, the module having a cylindrical shape through which the shaft portion can be inserted, and a main body that can be attached to the shaft portion so that its inner surface covers the peripheral surface of the shaft portion, the main body having a recess formed in the outer peripheral surface of the main body.

[0007] The module of the present disclosure is a module that can be attached to a shaft portion of a cutting tool having a shaft portion, and includes a columnar main body that can be attached to the shaft portion along the axial direction of the shaft portion, and the main body includes a recess formed on a circumferential surface of the main body, and a sensor mounting portion provided near the recess and capable of mounting a strain sensor.

[0008] The cutting tool unit of the present disclosure comprises a cutting tool including a shaft portion, and a module attachable to the shaft portion, the module having a cylindrical shape through which the shaft portion can be inserted, and including a main body attachable to the shaft portion such that its inner circumferential surface covers the circumferential surface of the shaft portion, and the main body has a recess on its outer circumferential surface.

[0009] The cutting tool unit of the present disclosure comprises a cutting tool including a shaft portion, and a module attachable to the shaft portion, the module including a columnar main body attachable to the shaft portion along the axial direction of the shaft portion, the main body including a recess formed on a circumferential surface of the main body, and a sensor mounting portion provided near the recess and capable of mounting a strain sensor.

[0010] The cutting system of the present disclosure comprises a cutting tool and a management device, the cutting tool including a shaft portion having an enlarged diameter portion having a larger diameter than other portions of the shaft portion, the enlarged diameter portion having a recess on its circumferential surface, the cutting tool further including a strain sensor attached to the shaft portion, the cutting tool transmitting sensor information indicating measurement results of the strain sensor, and the management device receiving the sensor information from the cutting tool and processing the measurement results indicated by the received sensor information.

[0011] The cutting system of the present disclosure comprises a cutting tool unit and a management device, wherein the cutting tool unit includes a cutting tool having a shaft portion, and a module attachable to the shaft portion, the module having a cylindrical shape through which the shaft portion can be inserted, and a main body attachable to the shaft portion so that its inner circumferential surface covers the circumferential surface of the shaft portion, the main body having a recess on its outer circumferential surface, the cutting tool unit further includes a strain sensor attached to the module, the cutting tool unit transmits sensor information indicating the measurement results of the strain sensor, and the management device receives the sensor information from the cutting tool unit and processes the measurement results indicated by the received sensor information.

[0012] The cutting system of the present disclosure comprises a cutting tool unit and a management device, wherein the cutting tool unit includes a cutting tool having a shaft portion and a module attachable to the shaft portion, the module having a columnar main body attachable to the shaft portion along the axial direction of the shaft portion, the main body including a recess formed on a circumferential surface of the main body and a sensor attachment portion provided near the recess and capable of attaching a strain sensor, the cutting tool unit further includes a strain sensor attached to the module, the cutting tool unit transmits sensor information indicating the measurement results of the strain sensor, and the management device receives the sensor information from the cutting tool unit and processes the measurement results indicated by the received sensor information.

[0013] The cutting tool of the present disclosure comprises a blade mounting portion and a shaft portion connected to the blade mounting portion, wherein the shaft portion is rod-shaped with a circular or polygonal circumferential surface in a cross section perpendicular to the central axis of the shaft portion, and the shaft portion includes a first section which is a portion along the central axis direction, a second section adjacent to one side of the first section in the central axis direction, and a third section adjacent to the other side of the first section in the central axis direction, and the rigidity of the first section is lower than the rigidity of the second section and the rigidity of the third section.

[0014] The cutting tool of the present disclosure comprises a shaft portion including an enlarged diameter portion having a larger diameter than other portions of the shaft portion, the enlarged diameter portion including a hollow portion formed inside the enlarged diameter portion.

[0015] The cutting tool of the present disclosure includes a shaft portion, the shaft portion including a hollow portion formed inside the shaft portion and a sensor mounting portion on a circumferential surface of the shaft portion, to which a strain sensor can be attached, the sensor mounting portion overlaps with the hollow portion when the hollow portion is projected onto the circumferential surface of the shaft portion in a direction perpendicular to the central axis direction of the shaft portion. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view showing a configuration of a cutting tool according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram illustrating amplification of strain in the cutting tool according to the first embodiment of the present disclosure. [Diagram 3] FIG. 3 is a schematic diagram illustrating amplification of strain in the cutting tool according to the first embodiment of the present disclosure. [Figure 4] FIG. 4 is a side view showing the configuration of the cutting tool according to the first embodiment of the present disclosure. [Diagram 5] FIG. 5 is a side view showing the enlarged diameter portion of the cutting tool according to the first embodiment of the present disclosure with the strain sensor removed. [Figure 6] FIG. 6 is a diagram showing a configuration of a cutting tool according to a first embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram for explaining a function of a recess in the cutting tool according to the first embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram for explaining a function of a recess in the cutting tool according to the first embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram showing a configuration of a cutting tool according to the first embodiment of the present disclosure. [Figure 10]FIG. 10 is a diagram showing another example of the configuration of the cutting tool according to the first embodiment of the present disclosure. [Figure 11] FIG. 11 is a diagram showing another example of the configuration of the cutting tool according to the first embodiment of the present disclosure. [Figure 12] FIG. 12 is a diagram illustrating an example of a strain sensor in the cutting tool according to the first embodiment of the present disclosure. [Figure 13] FIG. 13 is a diagram showing a configuration of a cutting tool according to the first embodiment of the present disclosure. [Figure 14] FIG. 14 is a diagram illustrating a configuration of a cutting system according to the first embodiment of the present disclosure. [Figure 15] FIG. 15 is a graph showing a simulation result for the cutting tool according to the first embodiment of the present disclosure. [Figure 16] FIG. 16 is a graph showing a simulation result for the cutting tool according to the first embodiment of the present disclosure. [Figure 17] FIG. 17 is a graph showing a simulation result regarding the shape of the recessed portion of the cutting tool according to the first embodiment of the present disclosure. [Figure 18] FIG. 18 is a graph showing a simulation result regarding the shape of the recessed portion of the cutting tool according to the first embodiment of the present disclosure. [Figure 19] FIG. 19 is a graph showing a simulation result regarding the shape of the recessed portion of the cutting tool according to the first embodiment of the present disclosure. [Figure 20] FIG. 20 is a graph showing the results of a simulation performed on the shape of the recessed portion of the cutting tool according to the first embodiment of the present disclosure. [Figure 21] FIG. 21 is a perspective view illustrating a first modification of the cutting tool according to the first embodiment of the present disclosure. [Figure 22] FIG. 22 is a view taken along an arrow showing Modification 1 of the cutting tool according to the first embodiment of the present disclosure. [Figure 23] FIG. 23 is a side view illustrating a first modification of the cutting tool according to the first embodiment of the present disclosure. [Figure 24]FIG. 24 is a partial cross-sectional view showing a configuration of a cutting tool according to Modification 1 of the first embodiment of the present disclosure. [Diagram 25] FIG. 25 is a partial cross-sectional view showing another example of a cutting tool according to the first modification of the first embodiment of the present disclosure. [Figure 26] FIG. 26 is a partial cross-sectional view showing another example of a cutting tool according to the first modification of the first embodiment of the present disclosure. [Figure 27] FIG. 27 is a side view illustrating a second modification of the cutting tool according to the first embodiment of the present disclosure. [Figure 28] FIG. 28 is a side view showing Modification 2 of the cutting tool according to the first embodiment of the present disclosure in a divided state. [Figure 29] FIG. 29 is a side view illustrating a third modification of the cutting tool according to the first embodiment of the present disclosure. [Diagram 30] FIG. 30 is an enlarged side view showing the vicinity of the enlarged diameter portion in FIG. [Diagram 31] FIG. 31 is a perspective view showing a configuration of a cutting tool according to a second embodiment of the present disclosure. [Diagram 32] FIG. 32 is a side view showing a configuration of a cutting tool according to a second embodiment of the present disclosure. [Diagram 33] FIG. 33 is a view taken along an arrow showing a configuration of a cutting tool according to a second embodiment of the present disclosure. [Diagram 34] FIG. 34 is a side view illustrating another example of the configuration of the cutting tool according to the second embodiment of the present disclosure. [Diagram 35] FIG. 35 is a perspective view showing another example of the configuration of the cutting tool according to the second embodiment of the present disclosure. [Diagram 36] FIG. 36 is a side view illustrating another example of the configuration of the cutting tool according to the second embodiment of the present disclosure. [Figure 37] FIG. 37 is a side view illustrating another example of the configuration of the cutting tool according to the second embodiment of the present disclosure. [Figure 38] FIG. 38 is a perspective view illustrating a first modification of the cutting tool according to the second embodiment of the present disclosure. [Figure 39]FIG. 39 is a side view illustrating a first modification of the cutting tool according to the second embodiment of the present disclosure. [Diagram 40] FIG. 40 is a view taken along an arrow showing a first modified example of a cutting tool according to a second embodiment of the present disclosure. [Diagram 41] FIG. 41 is a perspective view showing a configuration of a cutting tool unit according to the third embodiment of the present disclosure. [Diagram 42] FIG. 42 is a view taken along an arrow showing a configuration of a cutting tool unit according to a third embodiment of the present disclosure. [Diagram 43] FIG. 43 is a perspective view showing a configuration of a cutting tool unit according to a fourth embodiment of the present disclosure. [Diagram 44] FIG. 44 is a side view showing a cutting tool unit according to a fourth embodiment of the present disclosure in a divided state. [Diagram 45] FIG. 45 is a perspective view showing a cutting tool according to a fourth embodiment of the present disclosure. [Figure 46] FIG. 46 is a perspective view showing a configuration of a cutting tool according to a fifth embodiment of the present disclosure. [Figure 47] FIG. 47 is a cross-sectional view of the cutting tool of FIG. 46 taken along a plane including the central axis of the shaft portion. [Figure 48] FIG. 48 is a graph showing the results of a simulation performed on the cutting tool according to the fifth embodiment of the present disclosure. [Figure 49] FIG. 49 is a graph showing the results of a simulation performed on the cutting tool according to the fifth embodiment of the present disclosure. [Figure 50] FIG. 50 is a graph showing the results of a simulation performed on the shape of a cavity of a cutting tool according to a fifth embodiment of the present disclosure. [Figure 51] FIG. 51 is a graph showing the results of a simulation performed on the shape of a cavity of a cutting tool according to a fifth embodiment of the present disclosure. [Figure 52] FIG. 52 is a graph showing the results of a simulation performed on the shape of a cavity of a cutting tool according to a fifth embodiment of the present disclosure. [Figure 53]FIG. 53 is a graph showing the results of a simulation performed on the shape of a cavity of a cutting tool according to a fifth embodiment of the present disclosure. [Figure 54] FIG. 54 is a perspective view showing a configuration of a cutting tool according to a first modification of the fifth embodiment of the present disclosure. As shown in FIG. [Figure 55] FIG. 55 is a cross-sectional view of a cutting tool according to a first modification of the fifth embodiment of the present disclosure, taken along a plane including the central axis of the shaft portion. [Figure 56] FIG. 56 is a side view showing another example of the cutting tool according to the second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Conventionally, cutting tools such as milling cutters and drills have been developed.

[0018] [Problem that this disclosure aims to solve] By measuring the distortion of the cutting tool caused by cutting, it is possible to grasp, for example, the cutting resistance. An excellent technology capable of measuring such distortion is desired.

[0019] The present disclosure has been made to solve the above-mentioned problems, and has as its purpose to provide a cutting tool, a module, a cutting tool unit, and a cutting system that are capable of accurately measuring distortion of a cutting tool caused by cutting.

[0020] [Effects of this disclosure] According to the present disclosure, distortion of a cutting tool caused by cutting can be measured with high accuracy.

[0021] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0022] (1) A cutting tool according to an embodiment of the present disclosure comprises a shaft portion including an enlarged diameter portion having a larger diameter than other portions of the shaft portion, the enlarged diameter portion having a recess formed in a circumferential surface of the enlarged diameter portion.

[0023] In this way, the shaft portion includes an enlarged diameter portion having a recess, and the stiffness of the enlarged diameter portion can be locally reduced. This locally increases the strain generated during cutting. Therefore, by attaching a strain sensor to the location where the stiffness is locally reduced, the strain of the cutting tool generated during cutting can be accurately measured.

[0024] (2) A cutting tool according to an embodiment of the present disclosure includes a shaft portion, the shaft portion including a recess formed on a circumferential surface of the shaft portion, and a sensor mounting portion provided near the recess and capable of mounting a strain sensor.

[0025] In this way, by providing a sensor attachment portion on the shaft portion, the strain occurring in the recess and the periphery of the recess can be detected by the strain sensor. Furthermore, with this configuration, for example, when the rigidity of the entire shaft portion is secured to a certain degree, the rigidity of the shaft portion can be locally reduced. As a result, the strain occurring during cutting increases locally. Therefore, by attaching a strain sensor to the location where the rigidity is locally reduced, the strain of the cutting tool caused by cutting can be accurately measured.

[0026] (3) Preferably, the recess is formed along the circumferential direction of the shaft portion and has a rectangular shape in a cross section including a central axis of the shaft portion.

[0027] With this configuration, it is easy to adjust the rigidity of the shaft portion in the circumferential direction, and therefore it is easy to adjust the distortion in the circumferential direction. Also, machining of the recess is relatively easy. Therefore, it is possible to more reliably achieve both the accuracy of the distortion measurement of the cutting tool and the like.

[0028] (4) Preferably, the recess has a shape that is point-symmetrical with respect to a point of intersection between the central axis of the shaft portion and the plane, the normal to the plane being the central axis of the shaft portion.

[0029] With this configuration, the occurrence of anisotropic distortion can be suppressed. For example, when multiple strain sensors are attached to the circumferential surface of the shaft portion, the state of the cutting tool can be accurately reflected by the measurement values ​​of each strain sensor.

[0030] (5) Preferably, the shaft portion has at least one set of recesses provided in a plane normal to a central axis of the shaft portion, at positions that are point symmetric with respect to an intersection point between the central axis and the plane.

[0031] With this configuration, the occurrence of anisotropic distortion can be suppressed. For example, when multiple strain sensors are attached to the circumferential surface of the shaft portion, the state of the cutting tool can be accurately reflected by the measurement values ​​of each strain sensor.

[0032] (6) More preferably, the pair of recesses have the same width and depth.

[0033] With this configuration, the occurrence of anisotropic distortion can be more reliably suppressed. For example, when multiple strain sensors are attached to the circumferential surface of the shaft portion, the state of the cutting tool can be more accurately reflected in the measurement values ​​of each strain sensor.

[0034] (7) Preferably, a bottom surface of the recess in a cross section including a central axis of the shaft portion has a rounded shape.

[0035] With this configuration, it is possible to prevent excessive stress concentration near the bottom surface of the recess, thereby improving the durability of the cutting tool.

[0036] (8) Preferably, the shaft portion is provided with a mark indicating a position where the strain sensor is to be attached.

[0037] With this configuration, the user can attach the strain sensor to an appropriate position on the shaft portion, thereby preventing the measurement value from being affected by misalignment of the strain sensor attachment position.

[0038] (9) Preferably, the distance from a bottom surface of the recess to a central axis of the shaft portion is equal to or greater than the radius of the portion of the shaft portion other than the enlarged diameter portion.

[0039] With this configuration, the effect of the depth of the recess on the displacement of the cutting edge can be reduced, so that the amount of displacement of the cutting edge during cutting can be kept small.

[0040] (10) Preferably, the distance from a bottom surface of the recess to a central axis of the shaft portion is smaller than the radius of the shaft portion other than the enlarged diameter portion.

[0041] This configuration promotes an increase in strain that occurs locally during cutting, making it possible to measure strain with even greater accuracy.

[0042] (11) Preferably, the cutting tool further includes a strain sensor attached to the shaft portion.

[0043] With this configuration, the strain sensor can be used to accurately measure the strain that occurs in the shaft portion during cutting.

[0044] (12) More preferably, the strain sensor is attached to the shaft portion so as to straddle the recess.

[0045] With this configuration, the strain sensor can be disposed in a portion where strain is more likely to occur, so that strain in the cutting tool caused by cutting can be measured with even greater accuracy.

[0046] (13) Preferably, the width of the recess is not less than 0.1 mm and not more than 10 mm.

[0047] With this configuration, the width of the recess can provide the following effects. That is, by adopting such a width, the effect of the width of the recess on the displacement of the cutting edge can be reduced, so that the amount of displacement of the cutting edge during cutting can be kept small. Also, the possibility of the opposing walls of the recess coming into contact with each other during cutting can be reduced. Furthermore, when the strain sensor is attached so as to straddle the recess, that is, when the strain sensor is attached in a bridge shape, a relatively wide area of ​​the strain sensor is suspended in the air, so that the stress distribution near the center of the strain sensor becomes nearly uniform, and the effect of the displacement of the attachment position of the strain sensor on the measurement value can be reduced.

[0048] (14) Preferably, the depth of the recess is not less than 2 mm and not more than 40 mm.

[0049] This configuration provides the following effects due to the depth of the recess. That is, by adopting such a depth, the effect of the depth of the recess on the displacement of the cutting edge can be reduced, so that the amount of displacement of the cutting edge during cutting can be kept small. In addition, the distortion amplification effect is increased, so that distortion can be measured with even greater accuracy.

[0050] (15) A module according to an embodiment of the present disclosure is a module that can be attached to a shaft portion of a cutting tool having a shaft portion, the module having a cylindrical shape through which the shaft portion can be inserted, and a main body that can be attached to the shaft portion such that its inner circumferential surface covers a circumferential surface of the shaft portion, the main body having a recess formed in its outer circumferential surface.

[0051] In this way, the module has a cylindrical main body that can be attached to the circumferential surface of the shaft, and the main body has a recess, which locally reduces the rigidity of the module. Therefore, when cutting is performed with the module attached to the shaft, the strain generated in the module during cutting increases locally. Therefore, by attaching a strain sensor to the location where the rigidity is locally reduced, the strain generated by cutting can be accurately measured.

[0052] (16) A module according to an embodiment of the present disclosure is a module that can be attached to a shaft portion of a cutting tool having a shaft portion, and includes a columnar main body that can be attached to the shaft portion along an axial direction of the shaft portion, the main body including a recess formed on a circumferential surface of the main body and a sensor mounting portion provided near the recess and capable of mounting a strain sensor.

[0053] In this way, the module has a columnar main body that can be attached to the shaft, and the main body has a recess formed on its circumferential surface, which locally reduces the rigidity of the module. Therefore, when cutting is performed with the module attached to the shaft, the strain generated in the module during cutting increases locally. Therefore, by attaching a strain sensor to the location where the rigidity is locally reduced, the strain generated by cutting can be accurately measured.

[0054] (17) A cutting tool unit according to an embodiment of the present disclosure includes a cutting tool including a shaft portion and the module described in (15) above.

[0055] In this way, the configuration includes a module including a cylindrical main body that can be attached to the circumferential surface of the shaft portion and has a recess formed in the main body, and the rigidity of the module is locally reduced. Therefore, by performing cutting with the module attached to the shaft portion, the strain generated in the module during cutting increases locally. Therefore, by attaching a strain sensor to the location where the rigidity is locally reduced, the strain generated by cutting can be accurately measured.

[0056] (18) A cutting tool unit according to an embodiment of the present disclosure includes a cutting tool including a shaft portion and the module described in (16) above.

[0057] In this way, the module includes a columnar main body that can be attached to the shaft portion, and the module has a recess formed on the circumferential surface of the main body, so that the rigidity of the module is locally reduced. Therefore, when cutting is performed with the module attached to the shaft portion, the strain generated in the module during cutting increases locally. Therefore, by attaching a strain sensor to the portion of the module where the rigidity is locally reduced, the strain generated by cutting can be accurately measured.

[0058] (19) A cutting system according to an embodiment of the present disclosure includes the cutting tool described in (11) above and a management device, wherein the cutting tool transmits sensor information indicating the measurement results of the strain sensor, and the management device receives the sensor information from the cutting tool and processes the measurement results indicated by the received sensor information.

[0059] In this manner, by configuring the device to process the measurement results indicated by the sensor information, it is possible to estimate, for example, whether or not the blade portion is damaged and the lifespan of the blade portion based on the location of the distortion in the shaft portion and the magnitude of the distortion.

[0060] (20) A cutting system according to an embodiment of the present disclosure includes the cutting tool unit described in (17) or (18) above, and a management device, wherein the cutting tool unit further includes a strain sensor attached to the module, the cutting tool unit transmits sensor information indicating a measurement result of the strain sensor, and the management device receives the sensor information from the cutting tool unit and processes the measurement result indicated by the received sensor information.

[0061] In this manner, by configuring to process the measurement results indicated by the sensor information, it is possible to estimate, for example, whether or not the blade portion is damaged and the lifespan of the blade portion based on the location of the distortion in the module and the magnitude of the distortion.

[0062] (21) A cutting tool according to an embodiment of the present disclosure comprises a blade mounting portion and a shaft portion connected to the blade mounting portion, the shaft portion being rod-shaped with a circular or polygonal circumferential surface in a cross section perpendicular to a central axis of the shaft portion, the shaft portion including a first section which is a portion along the central axis direction, a second section adjacent to one side of the first section in the central axis direction, and a third section adjacent to the other side of the first section in the central axis direction, and the rigidity of the first section is lower than the rigidity of the second section and the rigidity of the third section.

[0063] In this way, the shaft portion having the first section can locally reduce the rigidity of the shaft portion. This locally increases the strain generated during cutting. Therefore, by attaching a strain sensor to the location where the rigidity is locally reduced, the strain of the cutting tool generated during cutting can be accurately measured.

[0064] (22) Preferably, the shaft portion includes a cutting side section continuous with the blade mounting portion, a gripping side section including an end portion different from the end portion on the blade mounting portion side, and an intermediate section located between the cutting side section and the gripping side section, the intermediate section having a thicker shape than the cutting side section and the gripping side section, and the first section, the second section, and the third section are provided in the intermediate section.

[0065] With this configuration, it is possible to locally reduce the rigidity of the intermediate section, which has a larger diameter than the other parts of the shaft. This locally increases the strain that occurs during cutting. Therefore, by attaching a strain sensor to the location where the rigidity is locally reduced, it is possible to accurately measure the strain of the cutting tool that occurs during cutting.

[0066] (23) Preferably, the first section includes a recess formed in a peripheral surface of the first section, and a sensor attachment portion provided in the vicinity of the recess and capable of attaching a strain sensor.

[0067] In this way, by providing a sensor attachment portion on the shaft portion, the strain occurring in the recess and the periphery of the recess can be detected by the strain sensor. Furthermore, with this configuration, for example, when the rigidity of the entire shaft portion is secured to a certain degree, the rigidity of the shaft portion can be locally reduced. As a result, the strain occurring during cutting increases locally. Therefore, by attaching a strain sensor to the location where the rigidity is locally reduced, the strain of the cutting tool caused by cutting can be accurately measured.

[0068] (24) Preferably, the first section has a recess formed on a circumferential surface of the first section.

[0069] In this way, the first section of the shaft portion has a recess, which locally reduces the rigidity of the shaft portion. This locally increases the strain generated during cutting. Therefore, by attaching a strain sensor to the location where the rigidity is locally reduced, the strain of the cutting tool generated during cutting can be accurately measured.

[0070] (25) Preferably, the first section includes a cavity formed therein.

[0071] In this way, because a cavity is formed inside the first section, the processing heat is transmitted inside the shaft portion so as to avoid the cavity, and is transmitted near the circumferential surface of the shaft portion. Therefore, by measuring the temperature of the circumferential surface of the shaft portion, the thermal distortion generated in the shaft portion can be grasped, and the distortion can be measured more accurately.

[0072] (26) A cutting tool according to an embodiment of the present disclosure includes a shaft portion, the shaft portion including an enlarged diameter portion having a larger diameter than other portions of the shaft portion, the enlarged diameter portion including a hollow portion formed inside the enlarged diameter portion.

[0073] In this way, because a cavity is formed inside the enlarged diameter portion, the processing heat is conducted inside the enlarged diameter portion so as to avoid the cavity, and is conducted near the peripheral surface of the enlarged diameter portion. Therefore, by measuring the temperature of the peripheral surface of the enlarged diameter portion, the thermal distortion occurring in the enlarged diameter portion can be grasped, and the distortion can be measured more accurately.

[0074] (27) A cutting tool according to an embodiment of the present disclosure includes a shaft portion, the shaft portion including a hollow portion formed inside the shaft portion and a sensor mounting portion on a circumferential surface of the shaft portion, to which a strain sensor can be attached, the sensor mounting portion overlaps with the hollow portion when the hollow portion is projected onto the circumferential surface of the shaft portion in a direction perpendicular to the central axis direction of the shaft portion.

[0075] In this way, because a cavity is formed inside the shaft, the processing heat is transmitted inside the shaft in a manner that avoids the cavity, and is transmitted near the circumferential surface of the shaft. Therefore, by measuring the temperature of the circumferential surface of the shaft, the thermal distortion generated in the shaft can be grasped, and the distortion can be measured more accurately.

[0076] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated. In addition, at least some of the embodiments described below may be arbitrarily combined.

[0077] <First embodiment> FIG. 1 is a perspective view showing a configuration of a cutting tool according to a first embodiment of the present disclosure.

[0078] The cutting tool 101 is, for example, an end mill used in a milling machine or the like, and is used to cut a cutting object made of metal or the like.

[0079] 1, cutting tool 101 includes shaft portion 11, blade attachment portion 12, a blade portion (not shown), and strain sensor 14. Note that cutting tool 101 may not include a blade portion. In addition, the blade portion may be fixed integrally to blade attachment portion 12, or may be detachably attached to blade attachment portion 12.

[0080] In the example shown in FIG. 4, the boundary between the shaft portion 11 and the blade attachment portion 12 is indicated by a two-dot chain line 41.

[0081] The shaft portion 11 is rod-shaped with a circular or polygonal circumferential surface in a cross section perpendicular to its central axis 17. The base material of the shaft portion 11 is made of, for example, cemented carbide for cutting tools or die steel.

[0082] [assignment] By measuring the distortion of a cutting tool caused by cutting, it is possible to grasp, for example, the cutting resistance. An excellent technology that can measure such distortion is desired. However, since cutting tools are manufactured to have high rigidity, the distortion generated is small, and it may be difficult to measure the distortion as it is.

[0083] In order to solve such problems, it is conceivable to intentionally reduce the rigidity of the cutting tool. However, simply reducing the rigidity of the cutting tool increases the displacement of the cutting tool due to cutting resistance, making it difficult to perform precise cutting and potentially reducing the durability of the cutting tool.

[0084] Therefore, in the cutting tool according to the embodiment of the present disclosure, such problems are solved by the following configuration.

[0085] The shaft portion 11 includes an expanded diameter portion 15 having a larger diameter than the remaining portion of the shaft portion 11 .

[0086] In detail, in the shaft portion 11, in the axial direction of the cutting tool 101, specifically in a portion (middle section) along the longitudinal direction X, an enlarged diameter portion 15 is provided which enlarges the diameter of the shaft portion 11 in the orthogonal direction Y, which is a direction perpendicular to the longitudinal direction X.

[0087] In the shaft portion 11, a cutting-side section 1101 is provided on the blade mounting portion 12 side of the enlarged diameter section 15, which is an intermediate section. The cutting-side section 1101 extends from the enlarged diameter section 15 toward the blade mounting portion 12 and includes one end of the shaft portion 11, i.e., the end on the blade mounting portion 12 side. At the end on the blade mounting portion 12 side, the shaft portion 11 is connected to the blade mounting portion 12.

[0088] In the shaft portion 11, a gripping side section 1102 is provided on the side opposite the blade mounting portion 12 side of the enlarged diameter section 15, which is an intermediate section. The gripping side section 1102 extends from the enlarged diameter section 15 in the opposite direction to the cutting side section 1101, and includes an end portion on the other side of the shaft portion 11, i.e., an end portion different from the end portion on the blade mounting portion 12 side. In the gripping side section 1102, a portion a predetermined distance from the end portion of the shaft portion 11 constitutes a shank 1103.

[0089] The longitudinal direction X of the cutting tool 101 is aligned with the longitudinal direction of the shaft portion 11. For example, the longitudinal direction X of the cutting tool 101 and the longitudinal direction of the shaft portion 11 are parallel to each other.

[0090] The expanded diameter portion 15 is formed, for example, in the shape of a polygonal prism, specifically, in the shape of a regular polygonal prism. The central axis of the expanded diameter portion 15 is positioned on the central axis 17 of the shaft portion 11.

[0091] More specifically, for example, the expanded diameter portion 15 is formed in an octagonal prism shape. Although the expanded diameter portion 15 is preferably in an octagonal prism shape, it may be in a square prism shape, a hexagonal prism shape, a decagonal prism shape, or a dodecagonal prism shape, for example. The expanded diameter portion 15 may also be in a cylindrical shape.

[0092] The expanded diameter portion 15 expands the diameter of the shaft portion 11 over the entire circumferential direction of the shaft portion 11. That is, the diameter of the expanded diameter portion 15 is larger than the diameter of the portion of the shaft portion 11 other than the expanded diameter portion 15. In other words, the expanded diameter portion 15 is thicker than the portion of the shaft portion 11 other than the expanded diameter portion 15. The diameter of the expanded diameter portion 15 refers to the maximum of the line segments that pass through the central axis 17 and have both ends on the circumferential surface of the expanded diameter portion 15 when viewed from the direction of the central axis 17. In the example shown in FIG. 1, the diameter of the expanded diameter portion 15 corresponds to the diagonal line at the end face of the octagonal prism.

[0093] The enlarged diameter portion 15 is a portion that increases the rigidity of the shaft portion 11. Even if the length of the shaft portion 11 is extended in order to attach the strain sensor 14 to the shaft portion 11, by providing the enlarged diameter portion 15, it is possible to suppress a decrease in the rigidity of the shaft portion 11.

[0094] The enlarged diameter portion 15 has a recess 16 on its peripheral surface (outer circumferential surface). In this case, the recess 16 is formed so as to be recessed toward the central axis 17 of the shaft portion 11.

[0095] 1, the recess 16 is formed along the circumferential direction of the shaft portion 11, and is rectangular in a cross-sectional view including the central axis 17 of the shaft portion 11. The recess 16 is formed, for example, continuously over the entire circumferential direction of the shaft portion 11. The circumferential direction of the shaft portion 11 means the direction along the peripheral surface of the shaft portion 11 when the shaft portion 11 is projected onto a plane having the central axis 17 of the shaft portion 11 as a normal line.

[0096] With this configuration, it becomes easier to adjust the rigidity of the shaft portion 11 in the circumferential direction, and therefore it becomes easier to adjust the distortion in the circumferential direction. In addition, it is relatively easy to process the recesses 16. This makes it possible to more reliably ensure both the rigidity of the cutting tool 101 and the accuracy of the distortion measurement of the cutting tool 101.

[0097] The recess 16 is formed in a central portion (first section) of the expanded diameter portion 15 in the direction of the central axis 17 of the shaft portion 11. In the expanded diameter portion 15, of the portions adjacent to the first section, the portion on the shank 1103 side is the second section, and the portion on the blade attachment portion 12 side is the third section.

[0098] The recess 16 is a portion that has the function of locally increasing the strain occurring in the enlarged diameter portion 15. Specifically, the recess 16 (i) reduces the rigidity of the first section of the enlarged diameter portion 15 below the rigidity of the second and third sections, i.e., locally reduces the rigidity of the enlarged diameter portion 15, (ii) makes the distance from the central axis 17 of the shaft portion 11 to the position where the strain sensor 14 is attached greater than the distance from the central axis 17 of the shaft portion 11 to the bottom surface of the recess 16 in the enlarged diameter portion 15, and (iii) causes local stress concentration in the enlarged diameter portion 15.

[0099] That is, with regard to the above (i), by locally reducing the section modulus of the enlarged diameter portion 15, the rigidity of the enlarged diameter portion 15 can be locally reduced, and thereby the strain generated in the enlarged diameter portion 15 can be locally increased. Therefore, by attaching the strain sensor 14 to the recess 16 of the enlarged diameter portion 15 or in the vicinity of the recess 16, the strain sensor 14 can measure a larger value of strain than when the strain sensor 14 is attached to a position other than the enlarged diameter portion 15 in the shaft portion 11.

[0100] The strain sensor 14 is attached to the shaft portion 11, for example, so as to straddle the recess 16, i.e., in a bridge shape. In this case, the strain sensor 14 may straddle the recess 16 along the central axis 17 of the shaft portion 11, or may straddle the recess 16 in a direction inclined with respect to the central axis 17 of the shaft portion 11. The inclination angle may be, for example, 45° with respect to the central axis 17 of the shaft portion 11.

[0101] The strain sensor 14 may be attached to the shaft portion 11 so as not to straddle the recessed portion 16. In this case, the strain sensor 14 is attached to the shaft portion 11 in the vicinity of the recessed portion 16, for example.

[0102] Regarding (ii) above, by attaching strain sensor 14 to the peripheral surface of enlarged diameter portion 15, the distance between the attachment position of strain sensor 14 and central axis 17 of cutting tool 101 becomes greater than the distance between the bottom of recess 16 in enlarged diameter portion 15 and central axis 17 of cutting tool 101. This will be explained in detail below.

[0103] Fig. 2 is a schematic diagram illustrating the amplification of strain in the cutting tool according to the first embodiment of the present disclosure. In detail, Fig. 2 is a schematic diagram illustrating that the magnitude of strain generated in the cutting tool 101 varies depending on the distance from the central axis 17 of the cutting tool 101.

[0104] 2, the strain generated in shaft portion 11 increases with increasing distance from central axis 17. That is, strain εa at a position farther from central axis 17 is greater than strain εb at a position closer to central axis 17. Therefore, by attaching strain sensor 14 to the circumferential surface of enlarged diameter portion 15, strain sensor 14 can measure a larger value of strain.

[0105] 3 is a schematic diagram illustrating the amplification of strain in the cutting tool according to the first embodiment of the present disclosure, specifically, the diagram is a schematic diagram showing the state in which stress concentration occurs around the recess 16 in the enlarged diameter portion 15 by the flow of force.

[0106] Regarding the above (iii), as shown in Fig. 3, in the vicinity of the recess 16 in the enlarged diameter section 15, the density of the flow lines 30 indicating the flow of force is high or the flow lines 30 are curved. Stress concentration occurs in such places, and distortion is likely to become large. In particular, in the portion 40 near the bottom of the recess 16, the density of the flow lines 30 is high and the flow lines 30 are curved. Therefore, by attaching the strain sensor 14 to the recess 16 or in the vicinity of the recess 16, the strain sensor 14 can measure a larger distortion.

[0107] In this way, the above functions (i) to (iii) of recess 16 amplify the strain, that is, the strain appears locally large in recess 16 and the vicinity of recess 16. By attaching strain sensor 14 to the location where the rigidity is locally reduced, the rigidity of cutting tool 101 is ensured while the strain of cutting tool 101 caused by cutting, for example, the strain caused by cutting resistance, can be accurately measured.

[0108] When the strain sensor 14 is attached to the shaft portion 11 so as to straddle the recess 16, it can measure a more amplified strain compared to when it is attached to the shaft portion 11 so as not to straddle the recess 16, thereby improving the measurement accuracy.

[0109] The blade attachment portion 12 is, for example, formed integrally with the shaft portion 11. The base material of the blade attachment portion 12 is made of, for example, a cemented carbide for cutting tools or die steel.

[0110] The blade attachment portion 12 is configured to allow the blade portion to be detachably attached. Specifically, for example, the blade attachment portion 12 and the blade portion are each formed with a screw hole. With the screw holes of the blade attachment portion 12 and the blade portion aligned, the blade portion can be attached to the blade attachment portion 12 by screwing a screw into each screw hole.

[0111] FIG. 4 is a side view showing the configuration of the cutting tool according to the first embodiment of the present disclosure.

[0112] The size and shape of the cross section of recess 16 when enlarged diameter portion 15 is cut along a plane 20 passing through central axis 17 of shaft portion 11 is constant throughout the circumferential direction of shaft portion 11. In Fig. 4, plane 20 is indicated by an imaginary two-dot chain line.

[0113] Note that recesses 16 may be formed discontinuously along the circumferential direction of shaft portion 11. In other words, a plurality of recesses 16 may be formed in a discontinuous state.

[0114] FIG. 5 is a side view showing the enlarged diameter portion of the cutting tool according to the first embodiment of the present disclosure with the strain sensor removed.

[0115] 5, a mark (sensor attachment portion) 21 indicating the position for attaching the strain sensor 14 is provided on the shaft portion 11. The mark 21 is, for example, a contour line indicating the area where the strain sensor 14 is attached.

[0116] With this configuration, the user can attach the strain sensor 14 to an appropriate position on the shaft portion 11. Therefore, it is possible to suppress the influence on the measurement value caused by a deviation in the attachment position of the strain sensor 14.

[0117] Fig. 6 is a diagram showing a configuration of a cutting tool according to a first embodiment of the present disclosure, in particular, a view seen from a direction indicated by an arrow A in Fig. 1.

[0118] 6, recess 16 has a shape that is point-symmetrical on plane 18, normal to central axis 17 of shaft portion 11, with respect to intersection 19 between central axis 17 and plane 18. In FIG. 6, plane 18 is indicated by an imaginary two-dot chain line.

[0119] With this configuration, the occurrence of anisotropic distortion can be suppressed, so that, for example, when multiple strain sensors 14 are attached to the circumferential surface of the shaft portion 11, the cutting tool 101 can be more accurately reflected in the measurement values ​​of each strain sensor 14.

[0120] Fig. 7 is a diagram for explaining a function of a recess in the cutting tool according to the first embodiment of the present disclosure, in detail, Fig. 7 is a schematic cross-sectional view of the cutting tool shown in Fig. 1 when the cutting tool is regarded as a cantilever beam.

[0121] With reference to FIG. 7, the cutting tool 101 is a cantilever beam having the following coefficients and variables. In the example shown in FIG. 7, the recess 16 is formed along the circumferential direction of the enlarged diameter portion 15 and is rectangular in a cross-sectional view including the central axis 17 of the shaft portion 11. The bottom surface of the recess 16 is a cylindrical surface. When a load, i.e., a cutting resistance F [N], is applied to the tip portion 45 in the longitudinal direction X of the cutting tool 101, the strain ε1 [ε] generated at the bottom surface of the recess 16 and the strain ε2 [ε] generated near the opening of the recess 16 are expressed by the following formulas (1) and (2), respectively. Note that the strains ε1 and ε2 are both absolute numbers. However, in this specification, [ε] is written after ε1 and ε2 to clearly indicate that ε1 and ε2 are strains.

[0122]

number

[0123]

number

[0124] Here, E is Young's modulus [MPa], Z is section modulus [mm^3], M is bending moment [Nmm], and e is the distance [mm] between the mounting position of the strain sensor 14 and the central axis 17 of the cutting tool 101. D is the diameter of the part where the recess 16 is formed in the shaft part 11 and is narrowed, that is, the constricted part. In other words, the constricted part is a narrow part where the width of the shaft part 11 is locally narrowed. F is the load applied to the tip part 45 of the cutting tool, that is, the cutting resistance [N], L is the distance [mm] between the tip part 45 of the cutting tool and the center position of the recess 16 in the longitudinal direction X, and a is a coefficient indicating the degree of strain increase due to stress concentration. According to the results of the simulation, when the width of the recess 16 is 3 mm or more, a is 1.5. The operator "^" represents exponentiation.

[0125] Fig. 8 is a diagram for explaining the function of the recess in the cutting tool according to the first embodiment of the present disclosure. In detail, Fig. 8 is a schematic cross-sectional view of the cutting tool having an enlarged diameter portion 15 in which no recess 16 is formed, when the cutting tool is regarded as a cantilever beam.

[0126] With reference to FIG. 8, cutting tool 101A is a cantilever beam with enlarged diameter portion 15 in the shape of a rectangular prism. Specifically, in enlarged diameter portion 15, a cross section perpendicular to the longitudinal direction X of cutting tool 101 is square. When a load F, i.e., cutting resistance, is applied to the tip of cutting tool 101A, strain εorigin[ε] generated on the peripheral surface of enlarged diameter portion 15 is expressed by the following formula (3). Note that strain εorigin is an absolute number. However, in this specification, [ε] is written after εorigin to clearly indicate that εorigin is a strain.

[0127]

number

[0128] Here, E is Young's modulus [MPa], Z is section modulus [mm^3], M is bending moment [Nmm], e is the distance [mm] between the mounting position of strain sensor 14 and central axis 17 of cutting tool 101, H is the length [mm] of one side of the square cross section perpendicular to the longitudinal direction X of cutting tool 101 in enlarged portion 15, F is the load applied to the tip of the cutting tool, i.e., the cutting resistance [N], and L is the distance [mm] between the tip of the cutting tool and strain sensor 14 in the longitudinal direction X of the cutting tool.

[0129] From equations (2) and (3), the strain ε2 [ε] is expressed by the following equation (4).

[0130] [Number]

[0131] That is, the magnification α of ε2[ε] to εorigin[ε] is expressed by the following equation (5).

[0132]

number

[0133] With reference to formula (5), it can be seen that the strain increases by a factor of α by forming recess 16 in enlarged diameter section 15. Furthermore, in formula (2), the larger the value of e / (D / 2), the larger the value of ε2 [ε]. Therefore, it can be seen that the deeper recess 16 is, the larger the value of ε2 [ε] is.

[0134] Fig. 9 is a diagram showing a configuration of a cutting tool according to a first embodiment of the present disclosure, specifically, a partial cross-sectional view showing a part of a shaft portion cut along a plane including a central axis of the shaft portion.

[0135] The width W1 of the recess 16 will be described with reference to FIG. 9. The width W1 of the recess 16 is the distance between the two opening ends of the recess 16 in the direction of the central axis 17. In the example shown in FIG. 9, the width W1 of the recess 16 is constant over the circumferential direction of the shaft portion 11. When the width W1 of the recess 16 is not constant, the width W1 of the recess 16 is the longest distance between the two opening ends of the recess 16 in the direction of the central axis 17. When the recess 16 is a cylindrical hole that opens in a circular shape on the circumferential surface of the shaft portion 11 or a square cylindrical hole that opens in a square shape, the width W1 of the recess 16 is the longest span length of the opening edge of the recess 16.

[0136] The smaller the width W1 of the recess 16, the smaller the effect on the rigidity of the cutting edge, and therefore the amount of displacement of the cutting edge during cutting work can be kept small. On the other hand, the recess 16 is likely to be largely displaced in the closing direction due to deformation caused by cutting resistance, and the opposing wall surfaces forming the recess 16 are likely to come into contact with each other. In addition, the stress change in the stress distribution at and around the recess 16 becomes large, and the effect on the measurement value due to the misalignment of the mounting position of the strain sensor 14 becomes large.

[0137] Furthermore, the larger the width W1, the higher the degree of stress concentration that occurs in the recess 16, and the higher the sensitivity of the strain sensor 14. Furthermore, for example, if the strain sensor 14 is attached so as to straddle the recess 16, i.e., in a bridge shape, a relatively wide area of ​​the strain sensor 14 is suspended in the air, so the stress distribution at the center position of the strain sensor 14 becomes nearly uniform, and the effect on the measurement value due to the deviation of the attachment position of the strain sensor 14 is reduced. On the other hand, the effect on the rigidity of the cutting edge becomes larger, and the amount of displacement of the cutting edge during cutting work increases.

[0138] The width W1 of the recess 16 is appropriately set by weighing the advantages and disadvantages of the width W1. The width W1 is, for example, 0.1 mm or more and 10 mm or less, preferably 0.5 mm or more and 4 mm or less, and more preferably 1 mm or more and 3 mm or less. The width W1 may be less than 0.1 mm or more than 10 mm.

[0139] With this configuration, the width of the recess 16 can provide the following effects. That is, by adopting such a width, the effect of the width of the recess 16 on the displacement of the cutting edge can be reduced, so that the amount of displacement of the cutting edge during cutting can be kept small. Also, the possibility that the opposing wall surfaces of the recess 16 will come into contact with each other during cutting can be reduced. Also, when the strain sensor 14 is attached so as to straddle the recess 16, that is, when the strain sensor 14 is attached in a bridge shape, a relatively wide range of the strain sensor 14 is suspended in the air, so that the stress distribution near the center of the strain sensor 14 becomes nearly uniform, and the effect of the displacement of the attachment position of the strain sensor 14 on the measurement value can be reduced.

[0140] Next, the depth De1 of the recess 16 will be described. The depth De1 of the recess 16 is the distance from the circumferential surface of the enlarged diameter portion 15 to the bottom surface 34 of the recess 16 along the radial direction of the shaft portion 11. In the example shown in FIG. 9, the depth De1 of the recess 16 is constant along the circumferential direction of the shaft portion 11. When the recess 16 is provided in a portion other than the enlarged diameter portion 15 of the shaft portion 11, the depth De1 of the recess 16 is the distance from the circumferential surface of the shaft portion 15 to the bottom surface 34 of the recess 16. In short, the depth De1 of the recess 16 is the distance from the surface of the shaft portion 11 where the recess 16 opens to the bottom surface 34 of the recess 16 along the radial direction of the shaft portion 11. Note that when the bottom surface 34 of the recess 16 is curved, the depth De1 of the recess 16 is the longest distance from the surface of the shaft portion 11 where the recess 16 opens to the bottom surface 34 of the recess 16.

[0141] The smaller the depth De1 of the recess 16, the smaller the effect on the rigidity of the cutting edge, so that the amount of displacement of the cutting edge during cutting work can be kept small. On the other hand, the effect of reducing the second moment of area and the effect of the distance from the central axis 17 of the cutting tool 101 to the position of the strain sensor 14 being larger than the distance from the central axis 17 to the peripheral surface of the shaft portion 11 other than the enlarged diameter portion 15 become smaller, so that the effect of amplifying the amount of strain becomes smaller. In other words, the sensitivity of the strain sensor 14 becomes lower.

[0142] In addition, the greater the depth De1 of the recess 16, the greater the effect of reducing the moment of inertia of area and the effect of the distance from the central axis 17 of the cutting tool 101 to the position of the strain sensor 14 being greater than the distance from the central axis 17 to the peripheral surface of the shaft portion 11 other than the enlarged diameter portion 15, and the greater the degree of stress concentration occurring in the recess 16, resulting in a greater amplification effect of the strain amount. In other words, the sensitivity of the strain sensor 14 becomes higher. On the other hand, the greater the effect on the rigidity of the cutting edge, resulting in a greater displacement of the cutting edge during cutting work.

[0143] The depth De1 of the recess 16 is appropriately set by weighing the advantages and disadvantages of the depth De1. The depth De1 is, for example, 2 mm or more and 40 mm or less, preferably 2 mm or more and 20 mm or less, and more preferably 2.5 mm or more and 10 mm or less. The depth De1 may be less than 2 mm or more than 40 mm.

[0144] With this configuration, the depth of the recess 16 can provide the following effects. That is, by adopting such a depth, the effect of the depth of the recess 16 on the displacement of the cutting edge can be reduced, so that the amount of displacement of the cutting edge during cutting can be kept small. In addition, the effect of amplifying the amount of distortion is increased, so that distortion can be measured with even greater accuracy.

[0145] Furthermore, when the expanded diameter portion 15 is cut along a plane 20 passing through the central axis 17 of the shaft portion 11, the shape of the bottom surface 34 of the recess 16 on the plane 20 is linear, as shown in FIG.

[0146] Furthermore, distance D1 from bottom surface 34 of recess 16 to central axis 17 of shaft portion 11 is, for example, equal to or greater than radius r1 of the portion of shaft portion 11 other than enlarged diameter portion 15. If bottom surface 34 of recess 16 is not shaped like a straight line, such as an arc, distance D1 is the shortest distance from bottom surface 34 of recess 16 to central axis 17 of shaft portion 11.

[0147] With this configuration, the effect of the depth of the recess 16 on the displacement of the cutting edge can be minimized, so that the amount of displacement of the cutting edge during cutting can be kept small.

[0148] Fig. 10 is a diagram showing another example of the configuration of the cutting tool according to the first embodiment of the present disclosure, specifically, a partial cross-sectional view showing a part of the shaft portion cut along a plane including the central axis of the cutting tool.

[0149] When the enlarged diameter portion 15 is cut by a plane passing through the central axis 17 of the shaft portion 11, the shape of the bottom surface 34 of the recess 16 on the plane 20 is not limited to a straight line, but may be, for example, a rounded shape, specifically, an arc shape, as shown in Figure 10.

[0150] With such a configuration, it is possible to prevent excessive stress concentration near the bottom surface of the recess 16, and therefore the durability of the cutting tool 101 can be improved.

[0151] 11 is a diagram illustrating another example of the configuration of the cutting tool according to the first embodiment of the present disclosure, specifically, a partial cross-sectional view showing a part of a shaft portion cut along a plane including the central axis of the cutting tool.

[0152] Referring to FIG. 11, the distance D1 may be smaller than the radius r1.

[0153] This configuration promotes an increase in strain that occurs locally during cutting, making it possible to measure strain with even greater accuracy.

[0154] FIG. 12 is a diagram illustrating an example of a strain sensor in the cutting tool according to the first embodiment of the present disclosure.

[0155] 12, the strain sensor 14 includes, for example, a semiconductor chip 31, a support portion 32, and an attachment portion 33.

[0156] The semiconductor chip 31 is, for example, a single semiconductor integrated circuit in which a sensor element, a control circuit, an amplifier circuit, and an A / D (Analog to Digital) converter are integrated.

[0157] The support portion 32 is a plate-shaped base made of metal that supports the semiconductor chip 31. The semiconductor chip 31 and the support portion 32 are sealed with synthetic resin.

[0158] The attachment portion 33 is a sheet-like member for adhering and attaching the semiconductor chip 31 and the support portion 32 to the shaft portion 11, which is the object to which they are to be attached.

[0159] The strain sensor 14 is attached to the shaft portion 11 by an adhesive or the like. Specifically, for example, a user can attach the strain sensor 14 to an attachment position on the shaft portion 11 that is indicated by a mark 21.

[0160] With this configuration, the strain sensor 14 can be used to accurately measure the strain that occurs in the shaft portion 11 during cutting.

[0161] The strain sensor 14 is attached to the enlarged diameter portion 15, for example, so as to straddle the recess 16, i.e., in a bridge shape. In this case, the strain sensor 14 is attached along a direction perpendicular to the recess 16, i.e., along the longitudinal direction X of the cutting tool 101. The strain sensor 14 is preferably attached at a position where the center of gravity of the strain sensor 14 faces the recess 16 in the radial direction of the shaft portion 11. The strain sensor 14 may be attached to the enlarged diameter portion 15 so as not to straddle the recess 16. In this case, the strain sensor 14 is attached, for example, in the vicinity of the recess 16 in the enlarged diameter portion 15. More specifically, the strain sensor 14 is attached at a position within 5 mm from the recess 16 in the direction of the central axis 17.

[0162] When the strain sensor 14 is attached to the enlarged portion 15 so as to straddle the recess 16, it can measure a more amplified strain than when it is attached to the enlarged portion 15 so as not to straddle the recess 16, thereby improving the measurement accuracy.

[0163] The strain sensor 14 can measure, for example, tensile strain and compressive strain occurring in the shaft portion 11 when the cutting tool 101 is cutting an object to be cut.

[0164] As the strain sensor 14, for example, a sensor manufactured by Glosel Corporation can be used.

[0165] Fig. 13 is a diagram showing a configuration of a cutting tool according to a first embodiment of the present disclosure. In detail, Fig. 13 is a diagram showing a state in which the cutting tool further includes a battery, a wireless communication device, and a housing in addition to the components shown in Fig. 2. In Fig. 13, the battery, the wireless communication device, and the housing are indicated by two-dot chain lines, which are imaginary lines.

[0166] 13, the cutting tool 101 further includes a battery 22, a wireless communication device 23, and a housing 24 in addition to the components shown in FIG.

[0167] The battery 22 is connected to the strain sensor 14 and the wireless communication device 23 via a power line (not shown). The battery 22 supplies power to the strain sensor 14 and the wireless communication device 23 via the power line. The power line is provided with a switch for turning the power supply on and off.

[0168] The wireless communication device 23 is connected to the strain sensor 14 via a signal line (not shown). The strain sensor 14 outputs a measurement signal indicating the strain generated in the shaft portion 11 to the wireless communication device 23 via the signal line.

[0169] When the wireless communication device 23 receives a measurement signal from the strain sensor 14, it transmits the measurement result indicated by the received measurement signal to a management device (described later) such as an external personal computer, while including the measurement result in a wireless signal. The management device, for example, accumulates the received measurement results and analyzes the accumulated measurement results. Note that the management device is not limited to analyzing the measurement results, and may perform other types of processing.

[0170] The housing 24 includes a bottom plate portion 25 and a side wall portion 26 .

[0171] Housing 24 is fixed, for example, to the lower surface of expanded diameter portion 15. Housing 24 holds battery 22 and wireless communication device 23 in a state in which expanded diameter portion 15, battery 22, wireless communication device 23, power lines, and signal lines are housed therein, specifically, in a state in which housing 24 covers expanded diameter portion 15, battery 22, etc. from below and sides thereof.

[0172] The bottom plate portion 25 is formed, for example, in a disk shape. A plurality of screw holes (not shown) are formed in the bottom plate portion 25 at positions corresponding to the enlarged diameter portion 15. A plurality of screw holes are also formed in the lower surface of the enlarged diameter portion 15.

[0173] With the screw holes in the bottom plate portion 25 and the screw holes in the enlarged diameter portion 15 aligned, the bottom plate portion 25 can be fixed to the enlarged diameter portion 15 by screwing screws into each of the screw holes in the bottom plate portion 25 and the enlarged diameter portion 15.

[0174] The side wall portion 26 is formed, for example, in a cylindrical shape. A plurality of screw holes (not shown) are formed in the lower end portion of the side wall portion 26 at positions corresponding to the peripheral portion of the bottom plate portion 25. A plurality of screw holes are also formed in the peripheral portion of the bottom plate portion 25.

[0175] With the screw holes in the bottom plate portion 25 and the screw holes in the side wall portion 26 aligned, the side wall portion 26 can be fixed to the bottom plate portion 25 by screwing screws into each screw hole in the bottom plate portion 25 and the side wall portion 26.

[0176] FIG. 14 is a diagram illustrating a configuration of a cutting system according to the first embodiment of the present disclosure.

[0177] Referring to FIG. 14, a cutting system 210 includes a cutting device 211 such as a milling machine, and a management device 213.

[0178] The cutting device 211 includes a cutting tool 101, a drive unit (not shown), and a control unit (not shown) that controls the drive unit. The drive unit is a motor or the like that drives the cutting tool 101. The control unit controls the rotation speed and the like of the drive unit.

[0179] The cutting tool 101 transmits a wireless signal including sensor information indicating the measurement result of the strain sensor 14 .

[0180] The management device 213 receives a wireless signal including the sensor information from the cutting tool 101, and processes the measurement results indicated by the received sensor information.

[0181] Specifically, the management device 213 includes a wireless communication unit 214 , a control unit 215 , a storage unit 216 , an operation input unit 217 , and a display unit 218 .

[0182] The wireless communication unit 214 wirelessly communicates with the wireless communication device 23 of the cutting tool 101. Specifically, the wireless communication unit 214 receives a wireless signal including the sensor information from the wireless communication device 23 of the cutting tool 101.

[0183] The operation input unit 36 ​​includes a user interface such as a keyboard and a mouse, etc. The operation input unit 217 accepts instructions and data input from the user.

[0184] The storage unit 216 includes, for example, a storage device such as a hard disk drive (HDD). Also, for example, the storage unit 216 includes an auxiliary storage device such as a compact disc read only memory (CD-ROM), a digital versatile disc read only memory (DVD-ROM), or a Blu-ray (registered trademark) disc read only memory (BD-ROM). Also, for example, the storage unit 216 includes a semiconductor memory such as a random access memory (RAM) and a read only memory (ROM).

[0185] The memory unit 216 stores programs and data for operating the control unit 215, measurement results received by the wireless communication unit 214 from the cutting tool 101, analysis results of the control unit 215, and the like.

[0186] The control unit 215 includes, for example, a CPU (Central Processing Unit). The control unit 215 analyzes the measurement results of the strain sensor 14. In detail, the control unit 215 analyzes the measurement results stored in the storage unit 216. The control unit 215 also controls each unit in the management device 213.

[0187] Specifically, for example, the control unit 215 estimates whether or not the blade portion is damaged and the lifespan of the blade portion based on the position where the distortion occurs in the shaft portion 11 and the magnitude of the distortion.

[0188] The display unit 218 is, for example, a display. The display unit 218 displays the analysis results of the control unit 215. The display unit 218 may be provided outside the management device 213.

[0189] Furthermore, in the case where it is difficult to directly transmit and receive wireless signals between the cutting device 211 and the management device 213 due to a long distance between them, etc., the cutting system 210 may include a relay device between them. In this case, the cutting device 211 transmits wireless signals to the management device 213 via the relay device.

[0190] [How to use] 13 and 14, a method of using the cutting tool 101 will be described.

[0191] First, the shank 1103 of the cutting tool 101 is fixed to a holder, such as an arbor, in a milling machine.

[0192] Next, a switch provided on the power line is turned from off to on, thereby supplying power from the battery 22 to the strain sensor 14 and the wireless communication device 23.

[0193] Next, the cutting tool 101 is rotationally driven so that the cutting tool 101 starts cutting the object to be cut.

[0194] When cutting is started, the cutting resistance that the cutting tool 101 receives from the workpiece generates stress and distortion in the blade portion, the blade attachment portion 12 and the shaft portion 11 .

[0195] The strain sensor 14 outputs a measurement signal indicating the strain generated in the shaft portion 11 to the wireless communication device 23 .

[0196] Next, the wireless communication device 23 transmits the sensor information indicating the measurement signal received from the strain sensor 14 to the external management device 213 in a wireless signal.

[0197] In the management device 213, the wireless communication unit 214 stores the measurement results indicated by the sensor information contained in the wireless signal received from the wireless communication device 23 in the memory unit 216. The memory unit 216 accumulates the measurement results received by the wireless communication unit 214 from the cutting tool 101. The control unit 215 analyzes the measurement results accumulated in the memory unit 216 in response to instructions input by the user via the operation input unit 217. The display unit 218 displays the analysis results.

[0198] Note that recess 16 does not have to be rectangular as described above, that is, formed along the circumferential direction of expanded diameter portion 15, when viewed in a cross section including central axis 17 of shaft portion 11. Specifically, recess 16 may be, for example, a cylindrical hole that opens in a circular shape, or a square tubular hole that opens in a square shape.

[0199] The strain sensor 14 may also be attached to the enlarged diameter portion 15 in a direction oblique to the recess 16, i.e., in a direction oblique to the longitudinal direction X of the cutting tool 101. Specifically, for example, the strain sensor 14 may be attached to the enlarged diameter portion 15 in a direction that forms an angle of 45° with respect to the longitudinal direction X.

[0200] In addition, when multiple strain sensors 14 are provided, some of the strain sensors 14 may be attached in a direction perpendicular to the recess 16, i.e., along the longitudinal direction X of the cutting tool 101, and other strain sensors 14 may be attached to the enlarged portion 15 along a direction inclined relative to the recess 16.

[0201] Specifically, for example, when four strain sensors 14 are provided, two strain sensors 14 are attached along a direction perpendicular to the recess 16, and the other two strain sensors 14 are attached to the enlarged diameter portion 15 along a direction inclined relative to the recess 16.

[0202] Moreover, recess 16 does not have to be formed along the circumferential direction of shaft portion 11. Recess 16 may be formed along a direction inclined with respect to the circumferential direction of shaft portion 11. In other words, recess 16 may be formed so as to intersect with a plane having central axis 17 of shaft portion 11 as a normal line.

[0203] Furthermore, recess 16 may have a shape that is not point-symmetrical with respect to intersection 19 between central axis 17 and plane 18, on plane 18 normal to central axis 17 of shaft portion 11. Specifically, for example, recess 16 may be formed along the circumferential direction of shaft portion 11 such that at least one of the depth and width is not uniform in the circumferential direction of shaft portion 11.

[0204] Furthermore, shaft portion 11 may have at least one set of recesses provided on plane 18, normal to central axis 17 of shaft portion 11, at positions that are not point-symmetric with respect to intersection 19 between central axis 17 and plane 18. Specifically, for example, three recesses 16 may be provided on the circumferential surface of expanded diameter portion 15 at positions that form 0°, 120°, and 240° with intersection 19 as the center, respectively.

[0205] Fig. 15 is a graph showing the results of a simulation performed on the cutting tool according to the first embodiment of the present disclosure. In detail, Fig. 15 shows the displacement of the entire cantilever when the same load is applied to the tip of each of three examples 1 to 3 and two comparative examples 1 and 2, which are cutting tools according to the first embodiment, and which are regarded as a cantilever. In Fig. 15, examples 1 to 3 and comparative examples 1 and 2 correspond to graphs G1 to G5, respectively.

[0206] The conditions for the three Examples 1 to 3 and Comparative Examples 1 and 2 are as follows. Comparative Example 1 is a cutting tool in which the enlarged diameter portion 15 and the recessed portion 16 are not formed. Specifically, the length and diameter of the shaft portion 11 are 65 mm and 25 mm, respectively. Comparative Example 2 has a length of the region in which the strain sensor 14 is attached that is extended by 40 mm compared to Comparative Example 1.

[0207] In Example 1, the length of the region for mounting the strain sensor 14 is extended by 40 mm compared to Comparative Example 1, and the extended portion is expanded into a quadrangular prism-like expanded diameter portion 15. The expanded diameter portion 15 has a square cross section with one side measuring 55 mm. In Example 1, a recess 16 having a width of 3 mm is formed along the circumferential direction of the expanded diameter portion 15. The diameter of the neck portion, which is the portion of the shaft portion 11 where the recess 16 is formed and which is narrowed, is 35 mm.

[0208] In Example 2, the diameter of the constricted portion is 25 mm, which is different from Example 1. In Example 3, the diameter of the constricted portion is 20 mm, which is different from Example 1.

[0209] 15, it can be seen that when the overall length is extended by 40 mm as in Comparative Example 2, the rigidity is significantly reduced and the displacement at the cutting edge is large compared to Comparative Example 1. It can also be seen that when an enlarged diameter portion 15 is provided as in Examples 1 to 3, the rigidity is increased and the displacement of the cutting edge is suppressed to a small value compared to Comparative Example 2.

[0210] Here, as an example, the inventors calculated and compared the rigidity of the cutting tools in Example 2 and Comparative Example 2. Specifically, first, the dimensions of the cutting tool in Example 2 were measured using a three-dimensional scanner. Next, based on the measurement results, a three-dimensional CAD (Computer Aided Design) model corresponding to the cutting tool in Example 2 was created. Processing was performed to remove the enlarged diameter portion 15 having the recess 16 from the created CAD model, and a CAD model corresponding to the cutting tool in Comparative Example 2 was created. The rigidity of each of these CAD models was calculated by the finite element method.

[0211] As a result, the rigidity of the CAD model corresponding to Example 2 was 2.54 times that of the CAD model corresponding to Comparative Example 2. Therefore, the rigidity of the cutting tool provided with the enlarged diameter portion 15 having the recess 16 is preferably 1.1 times or more, more preferably 1.5 times or more, and further preferably 2.0 times or more, of the rigidity of the cutting tool not provided with the enlarged diameter portion 15.

[0212] Fig. 16 is a graph showing the results of a simulation of the cutting tool according to the first embodiment of the present disclosure. In detail, Fig. 16 shows the distortions that occur in shaft portion 11 when the same load is applied to the tip portion for each of Examples 1 to 3 and Comparative Examples 1 and 2. In Fig. 16, Examples 1 to 3 and Comparative Examples 1 and 2 correspond to graphs G21 to G25, respectively.

[0213] 16, it can be seen that, as in Examples 1 to 3, when the enlarged diameter portion 15 is formed in the shaft portion 11, the rigidity is increased and the distortion is reduced. It can also be seen that, as in Examples 1 to 3, when the recess 16 is formed in the enlarged diameter portion 15, the rigidity of the enlarged diameter portion 15 is locally reduced and the distortion is increased. It can also be seen that, as in Examples 1 to 3, when the diameter of the constricted portion is changed, the distortion is increased. For example, as in Examples 1 to 3, it can be seen that the distortion increases as the diameter of the constricted portion decreases, that is, as the depth of the recess 16 increases. For example, the constricted portion of Example 3 has a smaller diameter than the constricted portion of Example 1, and therefore has a lower rigidity than the constricted portion of Example 1. Therefore, the degree of distortion amplification is greater in the constricted portion of Example 3 than in the constricted portion of Example 1.

[0214] Fig. 17 is a graph showing the results of a simulation of the shape of the recess of the cutting tool according to the first embodiment of the present disclosure. In detail, Fig. 17 shows the degree of effect that the width of the recess 16 has on the stress distribution of the strain sensor 14 when the same load is applied to the tip of each of the three examples 4 to 9, which are cutting tools according to the first embodiment, which are considered to be cantilevers. Here, the strain sensor 14 is attached to the enlarged diameter portion 15 so as to straddle the recess 16.

[0215] The horizontal and vertical axes in Fig. 17 respectively indicate the distance from the tip end of the cantilever on the portion of strain sensor 14 straddling recess 16, i.e., the portion above recess 16, to a plurality of sampling positions toward the base end, and the stresses generated at the plurality of sampling positions. In Fig. 17, Examples 4 to 9 correspond to graphs G31 to G36, respectively.

[0216] 7 shows an enlarged view of a recess and a part of a strain sensor in a cutting tool according to a first embodiment of the present disclosure. In detail, FIG. 7 shows an example of a plurality of sampling positions P in the strain sensor 14.

[0217] 7, the sampling positions P are provided at intervals of 0.25 mm from an end 141 on the tip side of the cantilever to the base side in the portion of the strain sensor 14 spanning the recess 16. That is, the sampling positions P are provided at a plurality of positions including the above-mentioned starting point. The above-mentioned starting point is, for example, a position 0.25 mm away from the end 141 to the base side.

[0218] The sampling positions P may be provided at intervals of 0.25 mm from the end portion 141 toward the base side, with the end portion 141 being the starting point of the sampling positions P. That is, the sampling positions P may be provided at the end portion 141.

[0219] The conditions for the six examples 4 to 9 are as follows. In the examples 4 to 9, the enlarged diameter portion 15 is formed in a regular octagonal prism shape. The distance between the mutually opposing faces of the regular octagonal prism is 56 mm. In the examples 4 to 9, the recesses 16 are formed along the circumferential direction of the enlarged diameter portion 15.

[0220] The diameter of the neck portion, which is the narrowed portion where the recess 16 is formed in the shaft portion 11, is 32 mm. The distance between each side surface of the regular octagonal prism and the bottom surface of the recess 16, i.e., the depth of the recess 16, is 12 mm.

[0221] The widths of the recesses 16 in Examples 4 to 9 are 0.5 mm, 1 mm, 2 mm, 3 mm, 6 mm, and 10 mm, respectively.

[0222] 17, when the width of recess 16 is in the range of 0.5 mm to 1 mm, the stress varies widely due to the narrow width. On average, it is about 19 MPa to 28 MPa, and the stress increases as the width increases. However, when the width is in the range of 3 mm or more, the stress saturates at about 30 MPa. Therefore, when the width is increased from 0.5 mm to 10 mm, the increase in stress is about 1.5 times.

[0223] Fig. 18 is a graph showing the results of a simulation of the shape of the recess of the cutting tool according to the first embodiment of the present disclosure. In detail, Fig. 18 shows the degree of influence that the width of the recess has on the rigidity ratio of the tip when the rigidity at the tip of each of six examples 4 to 9, which are cutting tools according to the first embodiment, is compared when the same load is applied to the tip of each of them, assuming that the six examples are cantilevers. In Fig. 18, the horizontal axis and vertical axis respectively indicate the width and rigidity ratio of the recess.

[0224] With reference to FIG. 18, when the width of recess 16 is changed from 0.5 mm to 10 mm, the rigidity ratio decreases by about 5%.

[0225] Fig. 19 is a graph showing the results of a simulation of the shape of the recess of the cutting tool according to the first embodiment of the present disclosure. In detail, Fig. 19 shows the degree of effect that the depth of the recess 16 has on the stress distribution of the strain sensor 14 when the cutting tool according to the first embodiment, which is one of four examples 10 to 13, is considered to be a cantilever and the same load is applied to the tip of each. Here, the strain sensor 14 is attached to the enlarged diameter portion 15 so as to straddle the recess 16.

[0226] The horizontal and vertical axes in Fig. 19 respectively indicate the distance from the tip end of the cantilever on the portion of strain sensor 14 straddling recess 16, i.e., the portion above recess 16, to a plurality of sampling positions toward the base end, and the stresses generated at the plurality of sampling positions. In Fig. 19, Examples 10 to 13 correspond to graphs G41 to G44, respectively.

[0227] 7, the sampling positions P are provided at 0.25 mm intervals from an end 141 on the tip side of the cantilever to the base side in the portion of the strain sensor 14 spanning the recess 16. That is, the sampling positions P are provided at a plurality of positions including the above-mentioned starting point. The above-mentioned starting point is, for example, a position 0.25 mm away from the end 141 to the base side.

[0228] The sampling positions P may be provided at intervals of 0.25 mm from the end portion 141 toward the base side, with the end portion 141 being the starting point of the sampling positions P. That is, the sampling positions P may be provided at the end portion 141.

[0229] The conditions for the four Examples 10 to 13 are as follows. The depths of the recesses 16 in Examples 10 to 13 are 0.5 mm, 5.5 mm, 12 mm, and 15.5 mm, respectively. The widths of the recesses 16 in Examples 10 to 13 are 3 mm. The diameters of the bottoms of the recesses 16 in Examples 10 to 13 are 55 mm, 45 mm, 32 mm, and 25 mm, respectively.

[0230] 19, when the depth of the recess 16 is 0.5 mm, the stress is about 2 MPa. In contrast, when the depth of the recess 16 is 15.5 mm, the stress is about 31 MPa. In other words, when the depth of the recess 16 is changed from 0.5 mm to 15.5 mm, the stress is amplified by about 15 times.

[0231] Fig. 20 is a graph showing the results of a simulation of the shape of the recess of the cutting tool according to the first embodiment of the present disclosure. In detail, Fig. 20 shows the degree of influence that the depth of the recess has on the rigidity ratio of the tip when the rigidity at the tip of each of the four examples 10 to 13, which are cutting tools according to the first embodiment, is compared when the same load is applied to the tip of each of the four examples, which are considered to be cantilevers. In Fig. 20, the vertical axis shows the rigidity ratio. The horizontal axis shows the diameter of the bottom of the recess and the depth of the recess.

[0232] Referring to FIG. 20, even if the depth of the recess 16 is increased from 0.5 mm to 15.5 mm, the stiffness ratio decreases by only about 4%.

[0233] From the above results, when comparing the width and depth of the recess 16, it is found that the depth of the recess 16 has a higher rate of increase in stress relative to the change in rigidity ratio than the width of the recess 16. In other words, in order to reduce the rigidity of the shaft portion 11 and amplify distortion while suppressing the decrease in rigidity at the tip of the cantilever beam, it is found that increasing the depth of the recess 16 is more effective than increasing the width of the recess 16.

[0234] It is to be noted that cutting tool 101 may not include strain sensor 14, and shaft portion 11 may be configured to allow strain sensor 14 to be detachably attached thereto.

[0235] [Variation 1] FIG. 21 is a perspective view illustrating a first modification of the cutting tool according to the first embodiment of the present disclosure.

[0236] 21, a cutting tool 201 according to the first modification includes a plurality of recesses 161 instead of the recesses 16 shown in FIG.

[0237] 21, the recess 161 is a hole that opens in a circular shape. The recess 161 is formed so as to be concave toward the central axis 17 of the shaft portion 11. Note that the recess 161 may be a hole that opens in a shape other than a circle. For example, the recess 161 may be a hole that opens in a square shape.

[0238] In the example shown in FIG. 21, a plurality of recesses 161 are formed at intervals along the circumferential direction of the shaft portion 11. Specifically, the number of recesses 161 is four. Of the four recesses 161, two recesses 161 are provided at positions opposite to each other with respect to the central axis 17 of the shaft portion 11. The other two recesses 161 are provided at positions opposite to each other with respect to the central axis 17 of the shaft portion 11. The recesses 161 are provided at positions aligned at equal intervals along the circumferential direction of the shaft portion 11. The number of recesses 161 is not limited to four, and may be, for example, one, two, three, or five or more.

[0239] 22 is a view taken along an arrow showing Modification 1 of the cutting tool according to the first embodiment of the present disclosure. In particular, FIG. 22 is a view taken along an arrow seen from a direction A in FIG.

[0240] 22, the expanded diameter portion 15 has at least one pair of recesses 161 provided in a plane 18 having a normal line parallel to the central axis 17 of the shaft portion 11, at positions that are point-symmetric with respect to an intersection 19 between the central axis 17 and the plane 18. In the example shown in FIG. 22, the expanded diameter portion 15 has two pairs of recesses 161.

[0241] Specifically, at least one pair of recesses 161 provided at that position have the same width and depth.

[0242] Moreover, the size and shape of the cross section of each recess 161 are the same when the expanded diameter portion 15 is cut by the plane 18. Moreover, when the expanded diameter portion 15 is cut by the plane 18, the shape of the bottom surface 191 of the recess 161 on the plane 18 is linear.

[0243] FIG. 23 is a side view illustrating a first modification of the cutting tool according to the first embodiment of the present disclosure.

[0244] 23, when enlarged diameter portion 15 is cut along a plane 20 passing through central axis 17 of shaft portion 11, the cross-sections of all recesses 161 have the same size and shape.

[0245] Furthermore, when the expanded diameter portion 15 is cut along a plane 20, the shape of the bottom surface 191 of the recess 161 on the plane 20 is linear.

[0246] Fig. 24 is a diagram showing a configuration of a cutting tool according to a first modified example of the first embodiment of the present disclosure, in detail, a partial cross-sectional view showing a part of a shaft portion cut along a plane including a central axis of the cutting tool.

[0247] 24, the depth De2 of the recess 161 is set to a value within the same range as the depth De1 of the recess 16 in FIG.

[0248] 9. The length of the recess 161 in the direction perpendicular to the depth direction, specifically, the diameter Di1, is set to a value within the same range as the width W1 of the recess 16 in FIG.

[0249] Further, distance D2 from bottom surface 191 of recess 161 to central axis 17 of shaft portion 11 is, for example, equal to or greater than radius r1 of the portion of shaft portion 11 other than expanded diameter portion 15.

[0250] Fig. 25 is a diagram showing another example of a cutting tool according to Modification 1 of the first embodiment of the present disclosure, in detail, a partial cross-sectional view showing a part of a shaft portion cut along a plane including a central axis of the cutting tool.

[0251] When the expanded portion 15 is cut along a plane 20 passing through the central axis 17 of the shaft portion 11, the shape of the bottom surface 191 of the recess 161 on the plane 20 is not limited to being linear, but may be, for example, arc-shaped, as shown in Figure 25.

[0252] Fig. 26 is a diagram showing another example of a cutting tool according to Modification 1 of the first embodiment of the present disclosure, in detail, a partial cross-sectional view showing a part of a shaft portion cut along a plane including a central axis of the cutting tool.

[0253] Referring to FIG. 26, the distance D2 may be smaller than the radius r1.

[0254] The number of pairs of recesses 161 that enlarged diameter portion 15 has is not limited to two, and may be, for example, one pair or three or more pairs.

[0255] The other configuration is similar to that of the cutting tool 101 described above, and therefore detailed description will not be repeated here.

[0256] With the configuration in which the recess 161 is formed to be recessed toward the central axis 17 of the shaft portion 11, the recess 16 can be formed on the circumferential surface of the shaft portion 11 where distortion is likely to occur, specifically, for example, on the circumferential surface of the enlarged diameter portion 15, thereby further reducing the rigidity of the shaft portion 11. Therefore, the distortion of the cutting tool 101 caused by cutting can be measured with even greater accuracy.

[0257] Since the enlarged diameter portion 15 has at least one set of recesses 161 arranged at a position that is point-symmetrical with respect to the intersection 19 of the central axis 17 and the plane 18, the occurrence of anisotropic distortion can be suppressed. Therefore, for example, when multiple strain sensors 14 are attached to the circumferential surface of the shaft portion 11, the state of the cutting tool 101 can be accurately reflected by the measurement values ​​of each strain sensor 14.

[0258] [Variation 2] Fig. 27 is a side view showing Modification 2 of the cutting tool according to the first embodiment of the present disclosure, and Fig. 28 is a side view showing Modification 2 of the cutting tool according to the first embodiment of the present disclosure in a disassembled state.

[0259] 27 and 28, the shaft portion 11 of a cutting tool 301 according to the second modification is configured to be separable in a longitudinal direction X of the shaft portion 11. As shown in FIG.

[0260] Specifically, for example, the shaft portion 11 is configured to be dividable at a position closer to the blade mounting portion 12 than the enlarged diameter portion 15 into a blade side portion 111, which is the portion on the blade mounting portion 12 side, and an anti-blade side portion 114, which is the portion opposite the blade mounting portion 12.

[0261] A male thread portion 111A is provided at the end of the blade side portion 111 opposite the blade mounting portion 12. A female thread portion 114A is provided at the end of the counter-blade side portion 114 facing the blade mounting portion 12. The blade side portion 111 and the counter-blade side portion 114 are connected by screwing the male thread portion 111A and the female thread portion 114A together. The blade side portion 111 and the counter-blade side portion 114 are separated by releasing the screwing between the male thread portion 111A and the female thread portion 114A.

[0262] In addition, a female thread may be provided at the end of the blade side portion 111 opposite the blade mounting portion 12, and a male thread may be provided at the end of the counter-blade side portion 114 on the blade mounting portion 12 side.

[0263] In addition, the shaft portion 11 may be configured to be separable, for example, at a position opposite the blade mounting portion 12 from the enlarged diameter portion 15, into a portion on the blade mounting portion 12 side and a portion opposite the blade mounting portion 12.

[0264] The other configuration is similar to that of the cutting tool 101 described above, and therefore detailed description will not be repeated here. [Variation 3] FIG. 29 is a side view illustrating a third modification of the cutting tool according to the first embodiment of the present disclosure.

[0265] 29, the enlarged diameter portion 15 of the cutting tool 401 according to the third modification has a recess 27 at a position where the strain sensor 14 is attached. Hereinafter, the recess 27 is also referred to as the mounting recess 27. In the example shown in FIG. 29, the mounting recess 27 is formed at a position in the enlarged diameter portion 15 that is perpendicular to the recess 16.

[0266] The mounting recess 27 is formed so as to be concave toward the central axis 17 of the shaft portion 11. The opening and bottom surface of the mounting recess 27 are each larger than the strain sensor 14. Specifically, the opening and bottom surface of the mounting recess 27 each have a shape, for example, that is a similarly enlarged version of the strain sensor 14. The depth of the mounting recess 27 is, for example, the same as the depth of the recess 16.

[0267] Fig. 30 is an enlarged side view showing the vicinity of the enlarged diameter portion in Fig. 29. For convenience, the strain sensor is not shown in Fig. 30.

[0268] 30, a mark 21 is provided on the bottom surface of the mounting recess 27. The user can mount the strain sensor 14 at the mounting position indicated by the mark 21.

[0269] The other configuration is similar to that of the cutting tool 101 described above, and therefore detailed description will not be repeated here.

[0270] Next, another embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and the description thereof will not be repeated.

[0271] <Second embodiment> The second embodiment of the present disclosure relates to a cutting tool having a recessed portion with a different shape than that of cutting tool 101 according to the first embodiment. The second embodiment is similar to cutting tool 101 according to the first embodiment except for the contents described below.

[0272] Fig. 31 is a perspective view showing a configuration of a cutting tool according to a second embodiment of the present disclosure. Fig. 32 is a side view showing a configuration of a cutting tool according to a second embodiment of the present disclosure. Fig. 33 is a diagram showing a configuration of a cutting tool according to a second embodiment of the present disclosure. In detail, Fig. 33 is a view seen from the direction of an arrow A in Fig. 21.

[0273] 31 to 33, cutting tool 501 is different from cutting tool 101 shown in Fig. 1 in that it includes a shaft portion 110 instead of shaft portion 11. Further, shaft portion 110 does not include an enlarged diameter portion. Further, a recess 162 is formed on the circumferential surface of shaft portion 110 instead of recess 16 shown in Fig. 1. A sensor attachment portion 21 to which strain sensor 14 can be attached is provided near recess 162.

[0274] In the example shown in FIG. 32, the boundary between the shaft portion 110 and the blade attachment portion 12 is indicated by a two-dot chain line 41.

[0275] The recess 162 is formed so that when cutting is performed with the cutting tool 501 while the strain sensor 14 is attached to the sensor mounting portion 21 of the shaft portion 110, the strain sensor 14 can detect the strain that occurs in at least either the recess 162 or the area around the recess 162.

[0276] In the example shown in FIGS. 31 to 33, the recesses 162 are formed along the circumferential direction of the shaft portion 110. As shown in FIG.

[0277] The recesses 162 are formed continuously over the entire circumferential direction of the shaft portion 110. In Fig. 33, the recesses 162 are indicated by dashed lines. Note that the recesses 162 may be formed discontinuously along the circumferential direction of the shaft portion 110. In other words, a plurality of recesses 162 may be formed in a discontinuous state.

[0278] As long as the shaft portion 110 has a certain degree of rigidity, high rigidity can be ensured even if no enlarged diameter portion is formed in the shaft portion 110, and therefore the influence of reduction in rigidity due to the formation of the recess 162 can be reduced. This makes it possible to minimize the displacement of the shaft portion 110 due to cutting resistance while still enabling the strain sensor 14 to measure strain.

[0279] 34 to 37 are side views showing other examples of the configuration of the cutting tool according to the second embodiment of the present disclosure.

[0280] In the example shown in Fig. 31, recess 162 is formed in an end mill, which is a type of cutting tool, but is not limited to this. For example, referring to Fig. 34, recess 162 may be formed in body portion 125, which is an example of a shaft portion of drill 502, which is a type of cutting tool.

[0281] 34, the shaft portion 110, the body portion 125, and the blade mounting portion 12 are integrally formed and arranged in this order. The boundary between the body portion 125 and the blade mounting portion 12 is indicated by a two-dot chain line 42.

[0282] Furthermore, with reference to Figs. 35 and 36, recess 162 may be formed in boss portion 120, which is an example of a shaft portion of milling cutter 503, which is a type of milling tool.

[0283] 35 and 36, the boss portion 120 and the blade mounting portion 12 are integrally formed. In Fig. 36, the boundary between the boss portion 120 and the blade mounting portion 12 is indicated by a two-dot chain line 43.

[0284] 35 and 36, a shaft portion 121 is connected to the end of the boss portion 120 opposite to the blade attachment portion 12. It is to be noted that the shaft portion 121 does not have to be connected to the boss portion 120.

[0285] Also, referring to FIG. 37, recess 162 may be formed in shaft portion 122 by a cutting tool 504, which is a type of turning tool.

[0286] 37, the shaft portion 122 and the blade mounting portion 12 are integrally formed. The boundary between the shaft portion 122 and the blade mounting portion 12 is indicated by a two-dot chain line 44.

[0287] [Variation 1] Fig. 38 is a perspective view illustrating a first modified example of the cutting tool according to the second embodiment of the present disclosure. Fig. 39 is a side view illustrating the first modified example of the cutting tool according to the second embodiment of the present disclosure.

[0288] 38 and 39, a cutting tool 601 according to the first modification includes a plurality of recesses 163 instead of the recesses 162 shown in FIG.

[0289] 38 and 39, recess 163 is a hole that opens in a circular shape. Recess 163 is formed so as to be concave toward central axis 17 of shaft portion 123. Note that recess 163 may be a hole that opens in a shape other than a circle. For example, recess 163 may be a hole that opens in a square shape.

[0290] 38 and 39, a plurality of recesses 163 are formed at intervals along the circumferential direction of shaft portion 123. Specifically, the number of recesses 163 is four. Of the four recesses 163, two recesses 163 are provided at positions opposite to each other with respect to central axis 17 of shaft portion 123.

[0291] The other two recesses 163 are provided at positions opposite to each other across the central axis 17 of the shaft portion 123. The recesses 163 are provided at positions spaced equally apart along the circumferential direction of the shaft portion 123. The number of recesses 163 is not limited to four, and may be, for example, two, three, five or more.

[0292] 40 is a diagram showing a first modified example of a cutting tool according to a second embodiment of the present disclosure. In particular, FIG. 40 is a diagram seen from a direction indicated by an arrow A in FIG.

[0293] 40, shaft portion 123 has at least one pair of recesses 163 provided in a plane 18 having a normal line parallel to central axis 17 of shaft portion 123, at positions that are point-symmetric with respect to intersection 19 between central axis 17 and plane 18. In the example shown in FIG.

[0294] Moreover, the size and shape of the cross section of each recess 163 are the same when shaft portion 123 is cut by plane 18. Moreover, when shaft portion 123 is cut by plane 18, the shape of bottom surface 191 of recess 163 on plane 18 is linear.

[0295] The number of pairs of recesses 163 that shaft portion 123 has is not limited to two, and may be, for example, one pair or three or more pairs.

[0296] The other configuration is similar to that of the cutting tool 501 described above, and therefore detailed description will not be repeated here.

[0297] In this way, the recess 162 formed in the shaft portion 110 is configured so that the strain occurring in at least one of the recess 162 and the periphery of the recess 162 can be detected by the strain sensor 14, so that, for example, when the rigidity of the entire shaft portion 110 is ensured to a certain degree, the rigidity of the shaft portion 110 can be locally reduced. As a result, the distortion occurring during cutting is locally increased.

[0298] Therefore, in the cutting tool according to the second embodiment of the present disclosure, by attaching the strain sensor 14 to a location where the rigidity is locally reduced, it is possible to accurately measure the distortion of the cutting tool 501 caused by cutting while ensuring the rigidity of the cutting tool 501.

[0299] Next, another embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and the description thereof will not be repeated.

[0300] <Third embodiment> The third embodiment of the present disclosure relates to a cutting tool unit in which the cutting tool does not have an enlarged diameter portion and has an enlarged diameter module instead of the enlarged diameter portion, as compared with the cutting tool 101 according to the first embodiment. The cutting tool unit is the same as the cutting tool 101 according to the first embodiment except for the contents described below.

[0301] FIG. 41 is a perspective view showing a configuration of a cutting tool unit according to the third embodiment of the present disclosure.

[0302] Referring to FIG. 41, the cutting tool unit 701 includes a cutting tool 801 and an enlarging module 150. The cutting tool 801 includes a cutting tool unit 701 and an enlarging module 150. The cutting tool unit 701 includes a cutting tool 801 and an enlarging module 150.

[0303] The cutting tool 801 includes a shaft portion 113 and a blade attachment portion 12 or a blade portion provided at the end of the shaft portion 113 .

[0304] The shaft portion 113 does not include the expanded diameter portion 15 shown in Fig. 1. Moreover, the shaft portion 113 does not have the recess 162 shown in Fig. 31 formed therein.

[0305] The diameter enlargement module 150 is configured to be attachable to the shaft portion 113. That is, the cutting tool unit 701 includes the diameter enlargement module 150 instead of the diameter enlargement portion 15, as compared to the cutting tool 101 shown in FIG.

[0306] Specifically, the diameter enlarging module 150 includes a main body 151, a connecting mechanism (not shown), and a strain sensor 14.

[0307] The main body 151 is formed in a cylindrical shape. The main body 151 has a cylindrical shape into which the shaft portion 113 can be inserted, and can be attached to the shaft portion 113 such that the inner peripheral surface covers the peripheral surface of the shaft portion 113. A recess 160 is formed on the peripheral surface of the main body 151.

[0308] The recess 160 has, for example, the same shape and dimensions as the recess 16 shown in FIG.

[0309] Fig. 42 is a diagram showing a configuration of a cutting tool unit according to a third embodiment of the present disclosure. In detail, Fig. 42 is a diagram showing the cutting tool with the expansion module removed and the expansion module as viewed from the direction of the arrow A in Fig. 41.

[0310] 42, the main body 151 is configured to be separable into a plurality of parts in the circumferential direction. In the example shown in Fig. 42, the main body 151 is configured to be separable into two parts, that is, two arc-shaped parts 151a and 151b each having a substantially semicircular shape when viewed from the A direction.

[0311] The arc-shaped portion 151a and the arc-shaped portion 151b are connected to each other by a connecting mechanism (not shown). Specifically, for example, the arc-shaped portion 151a and the arc-shaped portion 151b are connected to each other by a bolt and a nut. The arc-shaped portion 151a and the arc-shaped portion 151b have dimensions such that they are fixed in close contact with the circumferential surface of the shaft portion 113 when connected to each other.

[0312] The strain sensor 14 is attached to the main body 151 at a position similar to that of the strain sensor 14 shown in FIG.

[0313] The cutting tool unit 701 can be attached to and detached from the shaft portion 113 by connecting and disconnecting the diameter expansion module 150 using the above-mentioned connecting mechanism. After the diameter expansion module 150 is attached to the shaft portion 113, the cutting tool unit 701 can be used in the same manner as the cutting tool 101 shown in FIG.

[0314] The cutting tool 801 may be a type of cutting tool other than an end mill. For example, the cutting tool 801 may be a drill, which is a type of turning tool. The cutting tool 801 may also be a cutting tool, which is a type of turning tool.

[0315] In this manner, the rigidity of the diameter expansion module 150 is locally reduced by the configuration including the cylindrical main body 151 that can be attached to the circumferential surface of the shaft portion 113 and the recess 160 formed in the main body 151. Therefore, by performing cutting in a state where the diameter expansion module 150 is attached to the shaft portion 113, distortion occurring in the diameter expansion module 150 during cutting increases locally.

[0316] In addition, the configuration of the diameter expansion module 150 includes a cylindrical main body 151 that can be attached to the circumferential surface of the shaft portion 113, and the main body 151 has a recess 160 formed therein, thereby locally reducing the rigidity of the diameter expansion module 150. For this reason, by performing cutting with the diameter expansion module 150 attached to the shaft portion 113, distortion occurring in the diameter expansion module 150 during cutting increases locally.

[0317] Therefore, in the cutting tool unit according to the third embodiment of the present disclosure, by attaching the strain sensor 14 to a location where the rigidity is locally reduced, it is possible to accurately measure the distortion caused by cutting, for example the distortion caused by cutting resistance, while ensuring the rigidity required for cutting.

[0318] The other configuration is similar to that of the cutting tool 101 described above, and therefore detailed description will not be repeated here.

[0319] The cutting tool unit 701 may further include a battery 22, a wireless communication device 23, and a housing 24 as shown in Fig. 13 in addition to the configuration shown in Fig. 41. The housing 24 is fixed to the diameter expansion module 150 by a fixing member such as a screw.

[0320] Also, a cutting system including a cutting tool unit 701 may be constructed. Specifically, for example, a cutting system according to a third embodiment of the present disclosure includes a cutting tool unit 701 shown in Fig. 41 instead of the cutting tool 101 shown in Fig. 4, as compared with the cutting system 210 shown in Fig. 14.

[0321] Next, another embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and the description thereof will not be repeated.

[0322] <Fourth embodiment> The fourth embodiment of the present disclosure relates to a cutting tool unit in which a recess is not formed in the milling cutter 503, which is a cutting tool according to another example of the second embodiment, and further includes an attachment module. Other than the contents described below, the cutting tool unit is the same as the milling cutter 503 according to another example of the second embodiment.

[0323] Fig. 43 is a perspective view showing a configuration of a cutting tool unit according to a fourth embodiment of the present disclosure. Fig. 44 is a side view showing the cutting tool unit according to the fourth embodiment of the present disclosure in a disassembled state. Fig. 45 is a perspective view showing a cutting tool according to the fourth embodiment of the present disclosure.

[0324] 43 to 45, the cutting tool unit 902 includes a cutting tool 901 and an attachment module 1123. The ... 901 is a cutting tool unit.

[0325] The cutting tool 901 includes a shaft portion 112 and a blade attachment portion 12 or a blade portion (not shown) provided at the end portion of the shaft portion 112. The cutting tool 901 is a milling cutter in the example shown in Fig. 45 .

[0326] The shaft portion 112 is configured to be separable in the axial direction of the shaft portion 112, specifically in the rotation axis direction X1. Specifically, the shaft portion 112 is configured to be separable into a blade side portion 1121 which is the portion on the blade mounting portion 12 side, and a counter-blade side portion 1122 which is the portion opposite the blade mounting portion 12. In the example shown in Figures 43 to 45, the blade side portion 1121 is a boss portion, and the counter-blade side portion 1122 is a shaft portion.

[0327] In detail, a concave portion 1121B that is recessed toward the blade mounting portion 12 is formed at the end of the blade side portion 1121 opposite the blade mounting portion 12. Further, a convex portion 1122B that protrudes toward the blade mounting portion 12 is formed at the end of the counter-blade side portion 1122 on the blade mounting portion 12 side.

[0328] As indicated by arrow B1, the recess 1121B and the protrusion 1122B engage with each other, thereby connecting the blade side portion 1121 and the counter-blade side portion 1122. That is, the cutting tool 901 is constructed. On the other hand, by releasing the screw engagement between the recess 1121B and the protrusion 1122B, the shaft portion 112 is separated into the blade side portion 1121 and the counter-blade side portion 1122.

[0329] The attachment module 1123 is a member that can be attached to the shaft portion 112. Specifically, the attachment module 1123 includes a main body 1123C, and a convex portion 1123A and a concave portion 1123B that are attachment portions for attaching the main body 1123C to the shaft portion 112.

[0330] The main body 1123C is a columnar member that can be attached to the blade side portion 1121 along the axial direction of the blade side portion 1121, specifically along the rotation axis 170.

[0331] Specifically, a convex portion 1123A that protrudes toward the blade mounting portion 12 is formed at the end of the mounting module 1123 on the blade mounting portion 12 side. Also, a concave portion 1123B that is recessed toward the blade mounting portion 12 is formed at the end of the mounting module 1123 opposite the blade mounting portion 12.

[0332] As shown by arrow B2, the recess 1121B and the protrusion 1123A engage with each other, thereby connecting the blade side portion 1121 and the mounting module 1123. Also, as shown by arrow B3, the recess 1123B and the protrusion 1122B engage with each other, thereby connecting the mounting module 1123 and the counter-blade side portion 1122. In other words, the cutting tool unit 902 is formed.

[0333] On the other hand, by disengaging the recess 1121B from the protrusion 1123A and disengaging the recess 1123B from the protrusion 1122B, the cutting tool unit 902 is separated into the blade side portion 1121, the attachment module 1123 and the counter-blade side portion 1122.

[0334] A recess 1620 is formed on the peripheral surface of the mounting module 1123. The recess 1620 is formed so that when cutting is performed by the cutting tool unit 902 with the mounting module 1123 attached to the shaft portion 112 and the strain sensor 14 attached to the mounting module 1123, the strain occurring in the recess 1620 or around the recess 1620 can be detected by the strain sensor 14.

[0335] In the example shown in FIGS. 43 and 44, the recess 1620 is formed along the circumferential direction of the attachment module 1123.

[0336] The recess 1620 is formed continuously over the entire circumferential direction of the mounting module 1123. The recess 1620 may be formed discontinuously along the circumferential direction of the mounting module 1123. In other words, a plurality of recesses 1620 may be formed in a discontinuous state.

[0337] A convex portion may be formed on the end of the blade side portion 1121 opposite the blade mounting portion 12, and a concave portion may be formed on the end of the mounting module 1123 on the blade mounting portion 12 side. A convex portion may be formed on the end of the mounting module 1123 opposite the blade mounting portion 12, and a concave portion may be formed on the end of the counter-blade side portion 1122 on the blade mounting portion 12 side.

[0338] The other configuration is similar to that of the milling cutter 503 described above, so detailed description will not be repeated here.

[0339] The cutting tool 901 may be a type of cutting tool other than a milling cutter. For example, the cutting tool 901 may be a drill, which is a type of turning tool. The cutting tool 901 may also be a cutting tool, which is a type of turning tool.

[0340] In this manner, the mounting module 1123 includes a columnar main body 1123C that can be attached to the shaft portion 112, and the configuration in which the recess 1620 is formed on the peripheral surface of the main body 1123C locally reduces the rigidity of the mounting module 1123. For this reason, by performing cutting with the mounting module 1123 attached to the shaft portion 112, the distortion generated in the mounting module 1123 during cutting locally increases.

[0341] Furthermore, the configuration includes the mounting module 1123, which includes a columnar main body 1123C that can be attached to the shaft portion 112 and has recesses 1620 formed on the circumferential surface of the main body 1123C, thereby locally reducing the rigidity of the mounting module 1123. For this reason, by performing cutting with the mounting module 1123 attached to the shaft portion 112, distortion occurring in the mounting module 1123 during cutting increases locally.

[0342] Therefore, in the cutting tool unit according to the fourth embodiment of the present disclosure, by attaching the strain sensor 14 to a location in the mounting module 1123 where the rigidity is locally reduced, it is possible to accurately measure the distortion caused by cutting, for example the distortion caused by cutting resistance, while ensuring the rigidity required for cutting.

[0343] The cutting tool unit 902 may further include a battery 22, a wireless communication device 23, and a housing 24 as shown in Fig. 13 in addition to the configuration shown in Fig. 43. The housing 24 is fixed to the attachment module 1123 by a fixing member such as a screw or a bolt.

[0344] Also, a cutting system including a cutting tool unit 902 may be constructed. Specifically, for example, the cutting system according to the fourth embodiment of the present disclosure includes a cutting tool unit 902 shown in Fig. 43 instead of the cutting tool 101 shown in Fig. 4, as compared with the cutting system 210 shown in Fig. 14.

[0345] Next, another embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and the description thereof will not be repeated.

[0346] <Fifth embodiment> The fifth embodiment of the present disclosure relates to a cutting tool in which a cavity is formed instead of the recess in the cutting tool 101 according to the first embodiment. The fifth embodiment is similar to the cutting tool 101 according to the first embodiment except for the contents described below.

[0347] FIG. 46 is a perspective view showing a configuration of a cutting tool according to a fifth embodiment of the present disclosure.

[0348] Referring to FIG. 46, a cutting tool 1001 includes a shaft portion 130, a blade attachment portion 12, a blade portion (not shown), and a strain sensor 14.

[0349] The shaft portion 130 includes an expanded diameter portion 152 that has a larger diameter than the other portions of the shaft portion 130. The expanded diameter portion 152 is, for example, in the shape of an octagonal prism. No recesses are formed on the peripheral surface of the expanded diameter portion 152, and the eight faces that make up the peripheral surface are generally flat.

[0350] Marks (sensor mounting portions) 21 indicating positions for mounting strain sensors 14 are provided on the peripheral surface of enlarged diameter portion 152. More specifically, sensor mounting portions 21 are provided on each of eight faces constituting the peripheral surface of enlarged diameter portion 152. Sensor mounting portions 21 are, for example, contour lines indicating areas where strain sensors 14 are mounted. Each strain sensor 14 is disposed point-symmetrically with respect to central axis 17.

[0351] FIG. 47 is a cross-sectional view of the cutting tool of FIG. 46 taken along a plane including the central axis of the shaft portion.

[0352] 47, the expanded diameter portion 152 includes a hollow portion 28 formed inside the expanded diameter portion 152. The hollow portion 28 is a sealed space having a roughly cylindrical shape formed inside the expanded diameter portion 152. However, the hollow portion 28 may also be a sealed space having a roughly polygonal prism shape formed inside the expanded diameter portion 152, and the shape thereof is not particularly limited.

[0353] The central axis of cavity 28 coincides with central axis 17 of shaft portion 130. In the direction of central axis 17, the length of cavity 28 is shorter than the length of expanded diameter portion 152. Cavity 28 is formed in the central portion of expanded diameter portion 152 in the direction of central axis 17. The central portion of expanded diameter portion 152 corresponds to the first section. That is, the first section in expanded diameter portion 152 includes cavity 28 formed inside the first section. The first section is a portion of expanded diameter portion 152 where cavity 28 is formed radially inward, and is a portion of expanded diameter portion 152 from one end face to the other end face of cavity 28.

[0354] In the expanded diameter portion 152, of the portion adjacent to the first section, the portion on the shank 1103 side is the second section, and the portion on the blade mounting portion 12 side is the third section.

[0355] Strain sensor 14 is attached to the circumferential surface of expanded diameter portion 152 so as to straddle the first section. When cavity 28 is projected onto the circumferential surface of expanded diameter portion 152 in a direction perpendicular to central axis 17, i.e., along the radial direction of expanded diameter portion 152, strain sensor 14 overlaps with projected cavity 28. Strain sensor 14 and cavity 28 intersect with a plane having central axis 17 as a normal in the first section.

[0356] Strain sensor 14 may straddle the first section in a direction inclined with respect to central axis 17, or may be attached to expanded diameter portion 152 so as not to straddle the first section. However, strain sensor 14 is provided in the vicinity of the first section on the circumferential surface of expanded diameter portion 152. More specifically, strain sensor 14 is attached at a position within 5 mm in the direction of central axis 17 from projected cavity 28 when cavity 28 is projected onto the circumferential surface of expanded diameter portion 152 along the radial direction of expanded diameter portion 152.

[0357] The hollow portion 28 reduces the second moment of area of ​​the first section of the enlarged diameter portion 152, making the rigidity of the first section lower than the rigidity of the second and third sections. By locally reducing the second moment of area of ​​the enlarged diameter portion 152, it is possible to locally increase the strain generated in the enlarged diameter portion 152. Therefore, the strain sensor 14 can measure a larger value of strain than when it is attached to a position on the shaft portion 130 other than the first section of the enlarged diameter portion 152.

[0358] Moreover, the hollow portion 28 locally reduces the rigidity of the enlarged diameter portion, while increasing the distance from the central axis 17 of the shaft portion 130 to the position where the strain sensor 14 is attached. Since the strain at a position farther from the central axis 17 is larger than the strain at a position closer to the central axis 17, the strain sensor 14 can measure a larger value of strain.

[0359] Furthermore, heat generated by the cutting process is transferred from the blade portion to the shaft portion 130. When the shaft portion is solid, this processing heat is mainly transferred through the portion of the shaft portion near the central axis, so the temperature of the portion of the shaft portion near the central axis and the circumferential surface of the shaft portion where the strain sensor is attached are different. Therefore, even if the temperature of the circumferential surface of the shaft portion where the strain sensor is attached is measured, it is difficult to accurately grasp the thermal strain generated in the shaft portion.

[0360] In contrast, in cutting tool 1001 according to the fifth embodiment, cavity 28 is formed inside enlarged diameter portion 152, and therefore processing heat is transmitted to avoid cavity 28 as shown by the arrow in Fig. 47 and passes through the vicinity of the circumferential surface of enlarged diameter portion 152. Therefore, by measuring the temperature of the circumferential surface of shaft portion 130, it is possible to grasp the thermal distortion occurring in shaft portion 130 and measure the distortion more accurately. The cutting tool 1001 can be manufactured, for example, by a metal three-dimensional printer.

[0361] FIG. 48 is a graph showing the results of a simulation performed on the cutting tool according to the fifth embodiment of the present disclosure. In detail, FIG. 48 shows the displacement of the entire cantilever when the same load is applied to the tip of each of Example 14, which is the cutting tool 1001 according to the fifth embodiment, Example 1, which is the cutting tool 101 according to the first embodiment, and three Comparative Examples 1 to 3, which are considered to be cantilevers. In addition, in all of Examples 1 and 14 and Comparative Examples 1 to 3, the cutting tool has a quadrangular prism-shaped shaft portion including the enlarged portion for the sake of simplicity of calculation. In FIG. 48, Examples 1 and 14 and Comparative Examples 1 to 3 correspond to graphs G51 to G55, respectively. In addition, since there is a slight difference between the displacement of Example 1 and the displacement of Comparative Example 3, the graphs G51 and G55 overlap on the drawing.

[0362] The conditions of Example 1 and Comparative Examples 1 and 2 are the same as those of the first embodiment. The conditions of Example 14 and Comparative Example 3 are as follows. In Comparative Example 3, the length of the region for mounting the strain sensor 14 is extended by 40 mm compared to Comparative Example 1, and the extended portion is an expanded diameter portion whose diameter is expanded into a rectangular prism shape. The expanded diameter portion has a square cross section with one side measuring 55 mm. However, the expanded diameter portion does not have a recess or a cavity formed therein.

[0363] In Example 14, the length of the region for mounting the strain sensor 14 is extended by 15 mm compared to Comparative Example 1, and the extended portion is expanded into a quadrangular prism-like expanded diameter portion 152. The expanded diameter portion 152 has a square cross section with one side measuring 30 mm. In Example 14, a cylindrical hollow portion 28 is formed inside the expanded diameter portion 152 instead of a recess. The length of the hollow portion 28 in the direction of the central axis 17 is 3 mm, and the diameter is 25 mm.

[0364] 48, in Example 14, even if cavity 28 is formed in enlarged diameter portion 152, the displacement of the cutting edge is suppressed to a small value of approximately -0.04 mm, which is almost the same as in Example 1.

[0365] Fig. 49 is a graph showing the results of a simulation performed on a cutting tool according to a fifth embodiment of the present disclosure. In detail, Fig. 49 shows the distortions that occur in the shaft portion when the same load is applied to the tip portion for each of Examples 1 and 14 and Comparative Examples 1 to 3. In Fig. 49, Examples 1 and 14 and Comparative Examples 1 to 3 correspond to graphs G61 to G65, respectively.

[0366] 49, when cavity 28 is formed as in Example 14, the numerical variation of strain is larger than that in Example 1. Since the strain amplification effect depends on the ratio of the change in strain, not on the absolute value of the strain, it can be seen that Example 14 has a larger strain amplification effect than Example 1. It can also be seen that the strain in Example 14 is larger than that in Example 1.

[0367] Fig. 50 is a graph showing the results of a simulation of the shape of the cavity of the cutting tool according to the fifth embodiment of the present disclosure. In detail, Fig. 50 shows the degree of influence that the length of cavity 28 in the direction of central axis 17 has on the stress distribution of strain sensor 14 when the same load is applied to the tip of each of Examples 15 to 20, which are cutting tools according to the fifth embodiment, which are considered to be cantilevers. Here, strain sensor 14 is attached to enlarged diameter portion 152 so as to straddle the first section in which cavity 28 is formed.

[0368] The horizontal and vertical axes in Fig. 50 respectively indicate the distance from the tip end of the cantilever beam to the base side of multiple sampling positions in the portion of strain sensor 14 spanning the first section, i.e., the portion on the first section, and the stress generated at the multiple sampling positions. In Fig. 50, Examples 15 to 20 correspond to graphs G71 to G76, respectively. The conditions for Examples 15 to 20 are as follows.

[0369] In Example 15, the length of the region for mounting the strain sensor 14 is extended by 40 mm compared to the above-mentioned Comparative Example 1, and the extended portion is expanded into a quadrangular prism-like expanded diameter portion 152. The expanded diameter portion 152 has a square cross section with one side measuring 55 mm. In Example 15, a cylindrical hollow portion 28 is formed inside the expanded diameter portion 152 instead of a recess. The length of the hollow portion 28 in the direction of the central axis 17 is 3 mm, and the diameter is 45 mm.

[0370] In Examples 16 to 20, the expanded diameter portion 152 has a regular square prism shape. The distance between the opposing surfaces on the circumferential surface of the expanded diameter portion 152 is 55 mm. In Examples 16 to 20, a cylindrical hollow portion 28 is formed inside the expanded diameter portion 152. The diameter of the hollow portion 28 in Examples 16 to 20 is 45 mm, the same as in Example 14.

[0371] In Example 16, the length of cavity 28 in the direction of central axis 17 is 0.5 mm, in Example 17, the length of cavity 28 in the direction of central axis 17 is 1.0 mm, in Example 18, the length of cavity 28 in the direction of central axis 17 is 2.0 mm, in Example 19, the length of cavity 28 in the direction of central axis 17 is 6.0 mm, and in Example 20, the length of cavity 28 in the direction of central axis 17 is 10.0 mm. Other conditions are the same in Examples 15 to 20.

[0372] 50, when the magnitude of distortion in Examples 16 to 20 at a distance of 0 mm is examined with Example 15 as the reference, the magnitude of distortion in each of Examples 16 to 20 is within about 5% of Example 15. In other words, it can be seen that the degree of distortion amplification in Examples 16 to 20 is roughly the same as that of Example 15.

[0373] Fig. 51 is a graph showing the results of a simulation of the shape of the cavity of the cutting tool according to the fifth embodiment of the present disclosure. In detail, Fig. 51 shows the degree of influence that the length of cavity 28 in the direction of central axis 17 has on the rigidity ratio of the tip end when the rigidity at the tip end of six examples 15 to 20 of cutting tool 1001 according to the fifth embodiment is compared when the same load is applied to the tip end of each example, assuming that the examples are cantilevers. In Fig. 51, the horizontal and vertical axes respectively show the length of cavity 28 in the direction of central axis 17 and the rigidity ratio based on example 15.

[0374] 51, the rigidity of the cutting tools in Examples 16-20 was almost the same as that of the cutting tool in Example 15.

[0375] Fig. 52 is a graph showing the results of a simulation of the shape of the cavity of the cutting tool according to the fifth embodiment of the present disclosure. In detail, Fig. 52 shows the degree of influence that the diameter of cylindrical cavity 28 has on the stress distribution of strain sensor 14 when the cutting tool 1001 according to the fifth embodiment of the four examples 15, 21 to 23 are regarded as cantilevers and the same load is applied to the tip of each. Here, strain sensor 14 is attached to enlarged diameter portion 152 so as to straddle the first section in which cavity 28 is formed.

[0376] The horizontal and vertical axes in Fig. 52 respectively indicate the distance from the tip end of the cantilever beam in the portion spanning the first section in strain sensor 14, i.e., the portion on the first section of expanded diameter section 152, to multiple sampling positions toward the base side, and the stresses generated at the multiple sampling positions. In Fig. 52, Examples 15, and 21 to 23 correspond to graphs G81 to G84, respectively.

[0377] The conditions for Example 15 are as described above. The conditions for Examples 21 to 23 are as follows. The diameters of the hollow portions 28 in Examples 21 to 23 are 35 mm, 40 mm, and 50 mm, respectively. The length of the hollow portions 28 in the direction of the central axis 17 in Examples 15, 21 to 23 is 3 mm. Other conditions are the same in Examples 15, 21 to 23.

[0378] Referring to FIG. 52, when the diameter of the cavity 28 is 35 mm, the stress is about 3.2 MPa and is generally constant from one end to the other end of the strain sensor 14. When the diameter of the cavity 28 is 40 mm, the stress is about 3.1 MPa to 3.5 MPa and does not change significantly from one end to the other end of the strain sensor 14. When the diameter of the cavity 28 is 40 mm, the stress is about 3.8 MPa to 4.0 MPa and does not change significantly from one end to the other end of the strain sensor 14. When the diameter of the cavity 28 is 50 mm, the stress is about 4.7 MPa to 4.9 MPa and does not change significantly from one end to the other end of the strain sensor 14. In addition, when the diameter of the cavity 28 is changed from 35 mm to 50 mm, the stress is amplified by about 1.5 times.

[0379] Fig. 53 is a graph showing the results of a simulation of the shape of the cavity of the cutting tool according to the fifth embodiment of the present disclosure. In detail, Fig. 53 shows the degree of influence that the diameter of cavity 28 has on the rigidity ratio of the tip end when the rigidity at the tip end of each of four examples 15, 21 to 23, which are cutting tool 1001 according to the fifth embodiment, is compared when the same load is applied to the tip end of each of the examples, which are considered to be cantilevers. In Fig. 53, the vertical axis shows the rigidity ratio based on example 15. The horizontal axis shows the diameter of cavity 28.

[0380] With reference to FIG. 53, the rigidity of the cutting tools in Examples 21 to 23 was almost the same as the rigidity of the cutting tool in Example 15.

[0381] From the above results, it is found that cutting tool 1001 in which cavity 28 is formed inside enlarged diameter portion 153 has the same rigidity as a cutting tool in which a recess is formed on the circumferential surface of enlarged diameter portion 152. However, the variation in the magnitude of strain in Example 15 is larger than the variation in the magnitude of strain in Example 1. Therefore, it is found that the absolute value of strain is larger in the cutting tool in which cavity 28 is formed than in the cutting tool in which a recess is formed, and the strain amplification effect is larger.

[0382] [Variation 1] FIG. 54 is a perspective view showing a configuration of a cutting tool according to a first modification of the fifth embodiment of the present disclosure. As shown in FIG.

[0383] 54, a cutting tool 1002 is different from the cutting tool 1001 shown in Fig. 46 in that it includes a shaft portion 131 instead of the shaft portion 130. Furthermore, the shaft portion 131 does not include an enlarged diameter portion.

[0384] FIG. 55 is a cross-sectional view of a cutting tool according to a first modification of the fifth embodiment of the present disclosure, taken along a plane including the central axis of the shaft portion.

[0385] 55, the shaft portion 131 includes a hollow portion 28 formed inside the shaft portion 131, and a sensor attachment portion 21 on the circumferential surface of the shaft portion 131 to which the strain sensor 14 can be attached.

[0386] The sensor attachment portion 21 overlaps with the cavity portion 28 when the cavity portion 28 is projected onto the peripheral surface of the shaft portion 131 in a direction perpendicular to the direction of the central axis 17 of the shaft portion 131. The details of the cavity portion 28 are the same as those described above, and therefore will not be described in detail here. In short, the cutting tool 1002 according to the first modified example of the fifth embodiment is obtained by replacing the recess in the cutting tool according to the second embodiment with the cavity portion 28.

[0387] Even with this configuration, as described above, by locally reducing the second moment of area of ​​shaft portion 131, it is possible to locally increase the strain generated in shaft portion 131. Furthermore, since the processing heat passes near the circumferential surface of shaft portion 131, by measuring the temperature of the circumferential surface of shaft portion 131, it is possible to grasp the thermal strain generated in shaft portion 131, and it is possible to measure the strain more accurately.

[0388] The above-described embodiments should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0389] For example, in the cutting tool according to the second embodiment, the shaft portion may be integrated with the holder.

[0390] 56 is a side view showing another example of the cutting tool according to the second embodiment of the present disclosure. Referring to FIG 56, the cutting tool 505 includes a holder portion 115, a shaft portion 116, and a blade attachment portion 12.

[0391] The holder part 115 is attached to the main shaft 29 of the cutting device. The upper part of the holder part 115 has a truncated cone shape, and the lower part of the holder part 115 has a cylindrical shape with a narrowed center.

[0392] Shaft portion 116 has an octagonal prism shape and includes a recess 164 formed in the center in the central axial direction along the circumferential direction of shaft portion 116. One end side of shaft portion 116 is connected to holder portion 115. Shaft portion 116 is fixed to holder portion 115 by screws or the like and is integrated with holder portion 115. The diameter of shaft portion 116, i.e., the diagonal line at the end face of the octagonal prism, is the same as or smaller than the diameter of holder portion 115. In FIG. 56, the boundary between shaft portion 116 and holder portion 115 is indicated by two-dot chain line 46.

[0393] The blade attachment portion 12 is fixed to the other end of the shaft portion 116 by a screw or the like. The connecting portion of the blade attachment portion 12 with the shaft portion 116 has a cylindrical shape. The diameter of the connecting portion of the blade attachment portion 12 is the same as or larger than the diameter of the shaft portion 116.

[0394] The above description includes the following additional features. [Appendix 1] A cutting tool, comprising: A shaft portion is provided. the shaft portion includes an expanded diameter portion having a diameter larger than other portions of the shaft portion, The enlarged diameter portion has a recess formed on a peripheral surface of the enlarged diameter portion, The recess is formed along a circumferential direction of the enlarged diameter portion, The cutting tool further comprises: A strain sensor is provided that is attached to the shaft portion, The strain sensor is attached to the cutting tool so as to straddle the recess.

[0395] [Appendix 2] A cutting tool, comprising: A shaft portion is provided. The shaft portion is a recess formed on a circumferential surface of the shaft portion; a sensor attachment portion provided in the vicinity of the recess and capable of attaching a strain sensor; The recess is formed along a circumferential direction of the enlarged diameter portion, The cutting tool further comprises: A strain sensor is provided which is attached to the sensor attachment portion, The strain sensor is attached to the cutting tool so as to straddle the recess.

[0396] [Appendix 3] A module attachable to a shaft portion of a cutting tool having a shaft portion, a main body having a cylindrical shape into which the shaft portion can be inserted and which can be attached to the shaft portion such that an inner circumferential surface of the main body covers a circumferential surface of the shaft portion; The main body has a recess formed on an outer circumferential surface of the main body, The module further comprises: a strain sensor attached to the module; The strain sensor is mounted across the recess.

[0397] [Appendix 4] A module attachable to a shaft portion of a cutting tool having a shaft portion, a columnar body that can be attached to the shaft portion along an axial direction of the shaft portion, The body includes: A recess formed on a peripheral surface of the main body; a sensor attachment portion provided in the vicinity of the recess and capable of attaching a strain sensor; The module further comprises: a strain sensor attached to the module; The strain sensor is mounted across the recess.

[0398] [Appendix 5] a cutting tool including a shaft portion; and a module according to claim 3 or 4, The strain sensor is attached to the cutting tool unit so as to straddle the recess.

[0399] [Appendix 6] A cutting tool according to claim 1 or 2; A management device, The cutting tool transmits sensor information indicating a measurement result of the strain sensor; The management device receives the sensor information from the cutting tool and analyzes a measurement result indicated by the sensor information; A cutting system, wherein the strain sensor is mounted across the recess.

[0400] [Appendix 7] A cutting tool unit according to claim 5 or 6, and an analysis device, The cutting tool transmits sensor information indicating a measurement result of the strain sensor; The analysis device receives the sensor information from the cutting tool and analyzes a measurement result indicated by the received sensor information; A cutting system, wherein the strain sensor is mounted across the recess.

[0401] [Appendix 8] A shaft portion is provided. the shaft portion includes an expanded diameter portion in a partial region along the axial direction that expands a diameter of the shaft portion in a direction perpendicular to the axial direction, The enlarged diameter portion has a recess formed on a peripheral surface of the enlarged diameter portion. [Explanation of symbols]

[0402] 11,110~113,121~123,130 Shaft section 1101 Cutting side section 1102 Gripping side section 1103 Shank 12 Blade attachment part 14 Strain Sensor 15,152 Expanded diameter part 16,161,162,1620 Concave 17 Center axis 18,20 plane 19 intersection 21 Mark (sensor mounting part) 22 Batteries 23 Wireless communication devices 24 Housing 25 Bottom plate part 26 Side wall 27 Recess 28 Cavity 101, 201, 301, 401, 501~504, 601, 901, 1001,1002 Cutting tools 112 Shaft section 120 Boss 125 Body 141 The tip end of the cantilever on the part above the recess in the strain sensor 150 Expansion Module 151,1123C Main unit 210 Cutting System 211 Cutting equipment 213 Management device 214 Wireless Communication Department 215 Control Unit 216 Storage section 217 Operation input section 218 Display section 1121 Blade side part 1121B, 1123B Concave 1122 Opposite blade side part 1122B, 1123A Convex part 1123 Mounting Module 701,801 Cutting tool unit P Sampling position

Claims

1. 1. A cutting tool, comprising: A shaft portion is provided. the shaft portion includes a recess formed on a circumferential surface of the shaft portion, and a mounting recess formed in a region of the circumferential surface of the shaft portion that includes at least a portion of the recess, The cutting tool further comprises: A strain sensor is attached to a bottom surface of the mounting recess, The strain sensor is attached to the circumferential surface so as to straddle the recess.

2. A cutting tool, comprising: A shaft portion is provided. the shaft portion includes a recess formed on a circumferential surface of the shaft portion and a mounting recess formed on the circumferential surface of the shaft portion at a position intersecting the recess, The cutting tool further comprises: A strain sensor is attached to a bottom surface of the mounting recess, The depth of the mounting recess is the same as the depth of the recess.

3. The cutting tool according to claim 1 or 2, wherein the mounting recess has a shape similar to and enlarged from the shape of the strain sensor.

4. A cutting tool, comprising: A shaft portion is provided. the shaft portion includes a recess formed on a circumferential surface of the shaft portion, and a mounting recess formed in a region of the circumferential surface of the shaft portion that includes at least a portion of the recess, The cutting tool further comprises: A strain sensor is attached to a bottom surface of the mounting recess, The mounting recess has a shape that is a similar enlarged version of the strain sensor.

5. A cutting tool described in any one of claims 1 to 4, wherein the recess is formed around the entire circumference of the circumferential surface.

6. A cutting tool described in any one of claims 1 to 5, wherein the depth of the recess is greater than the width of the recess.

7. A cutting tool described in any one of claims 1 to 6, wherein the width of the recess is not less than 0.1 mm and not more than 10 mm.

8. A cutting tool described in any one of claims 1 to 7, wherein the depth of the recess is 2 mm or more and 40 mm or less.

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