Dimension measurement device, cutting tool system, and dimension measurement method

Abstract

This dimension measurement device comprises a sensor unit (3) and a measurement device body (100). The sensor unit (3) includes a first distance sensor (31) that uses an eddy current sensor, and a signal conversion unit (35A, 35B) that outputs, as a detection value, an output signal from the distance sensor for each preset time interval. The measurement device body (100) is provided with: a detection control unit (101) that causes the sensor unit (3) to detect the distance to a material being cut while rotating the material being cut; an acquisition unit (103) that acquires a plurality of detection values outputted from the sensor unit (3) for each time interval within a preset stipulated time; a calculation unit (105) that calculates the average value of the plurality of detection values acquired by the acquisition unit (103); and a result output unit (107) that outputs a measurement result for the material being cut, the measurement result being based on the average value of the detection values that was calculated by the calculation unit (105).

Description

Dimensional measurement device, cutting tool system, and dimension measurement method

[0001] This application claims priority to Japanese Patent Application No. 2023-204247, filed on December 1, 2023, the contents of which are incorporated herein by reference.

[0002] In recent years, development of cutting tools with various functions has been progressing. Patent Document 1 discloses a cutting tool equipped with a distance sensor. By incorporating a distance sensor in the cutting tool, it is possible to measure the dimensions of a workpiece immediately after processing, thereby shortening the time required for measurement and enabling efficient production.

[0003] Japanese Patent Application Publication No. 2022-151686 (A)

[0004] In the cutting tools described above, an eddy current sensor is used as a distance sensor. When measuring the dimensions of a workpiece using an eddy current sensor, measurement errors can occur due to a phenomenon known as electrical runout. The electrical runout phenomenon is thought to be caused by residual magnetism and uneven crystal structure in the steel that forms the workpiece. Due to this electrical runout phenomenon, when measuring the diameter of a workpiece after machining, the diameter measured by the eddy current sensor can vary depending on the circumferential position around the central axis of the workpiece.

[0005] In response to this problem, it is conceivable to measure the diameter of a workpiece by measuring the diameter of the workpiece at multiple positions around the circumference using an eddy current sensor and calculating the average of the measured values ​​at the multiple positions. However, measuring the diameter of a workpiece at multiple positions around the circumference is time-consuming and labor-intensive. Therefore, it is desirable to measure the diameter of a workpiece efficiently and with high accuracy.

[0006] In view of the above circumstances, one of the objects of the present invention is to provide a dimension measuring device, a cutting tool system, and a dimension measuring method that can measure the dimensions of a workpiece efficiently and with high accuracy.

[0007] One aspect of the dimension measuring device of the present invention is a dimension measuring device that measures a dimension in one direction of a workpiece that has been machined by rotating it relative to a cutting tool around a central axis, and includes a sensor unit that detects the distance to the machined surface of the workpiece in the one direction of the workpiece, and a measuring device main body that measures the dimension of the workpiece in the one direction based on the distance detected by the sensor unit, wherein the sensor unit includes a distance sensor using an eddy current sensor and a signal conversion unit that outputs a detection value based on an output signal of the distance sensor at preset time intervals, and the measuring device main body includes a detection control unit that causes the sensor unit to detect the distance to the workpiece while rotating the workpiece around the central axis of the workpiece, an acquisition unit that acquires a plurality of the detection values ​​output from the sensor unit at the time intervals within a preset specified time, a calculation unit that calculates the average value of the plurality of detection values ​​acquired by the acquisition unit, and a result output unit that outputs a measurement result of the workpiece based on the average value of the detection values ​​calculated by the calculation unit.

[0008] According to one aspect of the dimension measuring device of the present invention, a distance sensor using an eddy current sensor detects the distance to the workpiece while the workpiece is being rotated. The sensor unit outputs an output signal from the distance sensor as a detection value at predetermined time intervals. The measuring device main body calculates an average value of multiple detection values ​​output from the sensor unit at each time interval within a predetermined specified time, and obtains a measurement result of the workpiece based on the calculated average detection values. In this way, by obtaining multiple averaged detection values ​​from the sensor unit while rotating the workpiece and then averaging the multiple obtained detection values, it is possible to efficiently measure the dimension of the workpiece in one direction while suppressing the effects of electrical runout. As a result, it is possible to efficiently and accurately measure the dimension of the workpiece in one direction while rotating the workpiece.

[0009] In the above dimension measuring device, the signal conversion section may output, at every preset time interval, an average value of the output signals of the distance sensor within the time interval as the detection value.

[0010] In this case, by using a signal converter that outputs the average value of the output signal as the detection value, the analog output of the distance sensor can be averaged with higher accuracy. In addition, the following description of the embodiment will be given with reference to the case where this type of signal converter is used.

[0011] In the dimension measuring device, the detection control unit is configured to: －１ More than 1500min －１ The rotation may be performed at the following predetermined rotation speeds:

[0012] In this case, the workpiece is cut for 150 min. －１ More than 1500min －１ By measuring the dimensions of the workpiece in one direction while rotating it at the following specified rotation speed, the number of detected values ​​to be used for calculating the average value can be increased in a short time, thereby enabling the dimensional measurement of the workpiece in one direction to be performed more efficiently and with higher accuracy.

[0013] In the dimension measuring device, the acquisition unit may acquire the detection value while rotating the workpiece five or more times within the specified time period.

[0014] In this case, since the detected values ​​are acquired while rotating the workpiece five or more times within the specified time, the number of detected values ​​to be used for calculating the average value can be increased, thereby enabling the dimensional measurement of the workpiece in one direction to be performed with higher accuracy.

[0015] One aspect of the cutting tool system of the present invention includes the cutting tool having a tool body extending along the tool axis and having a base at its tip, and a cutting insert removably attached to the base, and the above-mentioned dimensional measuring device.

[0016] According to one aspect of the cutting tool system of the present invention, the dimension measuring device acquires multiple averaged detection values ​​from the sensor unit while rotating the workpiece, and then obtains the average value of the multiple acquired detection values, thereby efficiently measuring the dimension of the workpiece machined with the cutting tool in one direction while suppressing the effects of electrical runout.As a result, the dimension of the workpiece in one direction can be measured efficiently and with high accuracy while rotating the workpiece.

[0017] In the cutting tool system, the sensor unit may be attached to the cutting tool.

[0018] In this case, since the sensor unit is attached to the cutting tool, the sensor unit attached to the cutting tool can efficiently measure the dimensions in one direction of the workpiece machined by the cutting tool.

[0019] One aspect of the dimensional measurement method of the present invention is a dimensional measurement method for measuring the dimension in one direction of a workpiece that has been cut by rotating it relative to a cutting tool around a central axis, and includes the steps of: detecting the distance to the workpiece using a distance sensor that uses an eddy current sensor while rotating the workpiece around the central axis, and outputting the average value of the output of the distance sensor within a predetermined time interval as a detection value; acquiring a plurality of the detection values ​​output at each time interval within a predetermined specified time; calculating the average value of the acquired detection values; and outputting a measurement result of the workpiece based on the calculated average value of the detection values.

[0020] According to one aspect of the dimension measurement method of the present invention, by obtaining multiple detection values, which are average values ​​of the outputs of the distance sensors, while rotating the workpiece, and then averaging the multiple detection values, it is possible to efficiently measure the dimension of the workpiece in one direction while suppressing the influence of the electrical runout phenomenon.As a result, it is possible to efficiently and accurately measure the dimension of the workpiece in one direction while rotating the workpiece.

[0021] According to the dimension measuring device, cutting tool system, and dimension measuring method of one aspect of the present invention, the dimension of a workpiece in one direction can be measured efficiently and with high accuracy.

[0022] 1 is a diagram showing a cutting tool system according to one embodiment of the present invention; FIG. 2 is a functional block diagram of a measuring device main body constituting a dimension measuring device according to one embodiment of the present invention; FIG. 3 is a flowchart showing the flow of a dimension measuring method according to one embodiment of the present invention; FIG. 4 is a diagram showing a machining process according to one embodiment of the present invention; FIG. 5 is a diagram showing a state in which distance detection in the radial direction of a workpiece is performed in a distance detection process according to one embodiment of the present invention; FIG. 6 is a diagram showing the variation in the detected distance to the machined surface of the workpiece in the radial direction due to the electrical runout phenomenon; FIG. 7 is a diagram showing the variation in the detected distance to the machined surface of the workpiece in the radial direction when the rotation speed of the workpiece is changed; FIG. 8 is a diagram showing the average value of the detected values ​​to the machined surface of the workpiece in the radial direction when the number of rotations of the workpiece is changed; and FIG. 9 is a diagram showing the variation in the average value of the detected values ​​to the machined surface of the workpiece in the radial direction when radial dimension measurement of the workpiece is repeated.

[0023] A turning tool (cutting tool) 1 according to an embodiment of the present invention will be described below with reference to the drawings. In the drawings, the scale and number of components may differ from the actual structure in order to make each component easier to understand.

[0024] <Turning Tool System> Fig. 1 is a diagram showing a turning tool system (cutting tool system) 10 according to an embodiment of the present invention. As shown in Fig. 1, the turning tool system 10 includes a turning tool 1 and a measuring device main body 100.

[0025] The turning tool 1 of this embodiment performs turning, such as boring, on a workpiece such as a metal material that is rotated around a spindle of a machine tool (not shown). The turning tool 1 of this embodiment is made of metal and includes a tool body 2, a cutting insert 4, and a head unit 7.

[0026] The tool body 2 extends in an axial direction Dj along the tool axis J. The tool body 2 has a cylindrical shank portion 21 centered on the tool axis J, and a head portion 22 provided on one side Dj1 of the shank portion 21 in the axial direction Dj of the tool body 2.

[0027] The head portion 22 has a protrusion 23 that protrudes from the outer peripheral surface of the shank portion 21 outward in a radial direction Dr of the tool body 2 that intersects with the axial direction Dj. A base 23d is provided on the protrusion 23. A cartridge 41 is attached to the base 23d. The cartridge 41 holds the cutting insert 4. The base 23d and the cutting insert 4 attached to the cartridge 41 are arranged on a first side Dr1 in the radial direction Dr with respect to the tool axis J in the tool body 2. The cutting insert 4 may also be attached directly to the base 23d.

[0028] The cutting insert 4 has a diamond shape when viewed in the thickness direction. The cutting insert 4 has a pair of diamond-shaped main surfaces in a plan view facing the thickness direction and side surfaces connecting the pair of main surfaces. A cutting edge 42 is provided on the ridge between the main surfaces and the side surfaces of the cutting insert 4. The cutting edge 42 is provided at the tip portion of one side Dj1 in the axial direction Dj of the tool body 2. A portion of the cutting edge 42 protrudes from the tool body 2 to the one side Dj1 in the axial direction Dj. Furthermore, the cutting edge 42 protrudes outward in the radial direction Dr of the tool body 2. Therefore, a portion of the cutting edge 42 is located at the forefront of the one side Dj1 in the axial direction Dj of the tool body 2 and at the outermost end in the radial direction Dr.

[0029] According to this embodiment, the cutting insert 4 is fixed to the tool body 2 via the cartridge 41. Therefore, by replacing the cartridge 41, cutting inserts 4 of various shapes can be fixed to the tool body 2, thereby increasing the versatility of the tool body 2.

[0030] The head unit 7 is provided in the head portion 22. The head unit 7 includes a holder member 70, a sensor unit 3, an imaging device 5, and an illumination device 6. The head unit 7 is disposed in the tool body 2 on a second side Dr2 in the radial direction Dr with respect to the tool axis J. That is, the head unit 7 is disposed on the opposite side of the tool axis J from the base 23d and the cutting insert 4 attached to the base 23d in the radial direction Dr of the tool body 2. The holder member 70 is detachably attached to the tool body 2.

[0031] The sensor unit 3 includes a first distance sensor 31 and a second distance sensor 32. The first distance sensor 31 and the second distance sensor 32 are held by a holder member 70. The holder member 70 is attached to the head unit 22. In this embodiment, the first distance sensor 31 and the second distance sensor 32 measure the distance to the machined surface machined using the cutting insert 4. The sensor unit 3, together with the measuring device main body 100, constitutes a dimension measuring device M.

[0032] The first distance sensor 31 is arranged facing outward in the radial direction Dr from the outer peripheral surface of the tool body 2. The first distance sensor 31 measures the distance to a measurement object arranged outside the radial direction Dr of the tool body 2. That is, the measurement direction of the first distance sensor 31 is the radial direction Dr. The first distance sensor 31 measures the distance to a machined surface machined by the cutting insert 4 facing inward in the radial direction Dr.

[0033] The second distance sensor 32 is disposed facing one side Dj1 in the axial direction Dj from the head portion 22 of the tool body 2. The second distance sensor 32 measures the distance to a measurement object disposed on the one side Dj1 in the axial direction Dj of the tool body 2. That is, the measurement direction of the second distance sensor 32 is the axial direction Dj. The second distance sensor 32 measures the distance to a machined surface machined by the cutting insert 4 and facing the other side Dj2 in the axial direction Dj.

[0034] The first distance sensor 31 and the second distance sensor 32 are eddy current sensors. Eddy current sensors tend to maintain stable measurement accuracy despite disturbances, such as those in the surrounding environment. Therefore, eddy current sensors are more suitable for distance measurement in a disturbance-prone environment after cutting, compared to optical distance sensors, regardless of whether wet or dry machining is selected. The first distance sensor 31 and the second distance sensor 32 generate a high-frequency magnetic field by passing a high-frequency current through them. This causes eddy currents to flow on the surface (machined surface) of the measurement object, which is a conductor, and changes the impedance of the coils inside the first distance sensor 31 and the second distance sensor 32. The first distance sensor 31 and the second distance sensor 32 detect the distance to the measurement object from this change in impedance. The first distance sensor 31 and the second distance sensor 32 output a voltage (unit: V) indicating the change in impedance as their output value.

[0035] The first distance sensor 31 and the second distance sensor 32 are used to measure the machined surface after the turning tool 1 forms it. Because the first distance sensor 31 and the second distance sensor 32 are provided on the tool body 2, the machined surface after cutting can be measured without first separating the turning tool 1 from the workpiece. This shortens the time required to measure the machined surface during turning. Furthermore, the first distance sensor 31 can be used to measure the distance to the machined surface facing inward in the radial direction Dr machined by the cutting insert 4, and the second distance sensor 32 can be used to measure the distance to the machined surface facing the other side Dj2 in the axial direction Dj machined by the cutting insert 4. In other words, during dimensional measurement, dimensional measurements of surfaces facing in different directions can be performed without changing the orientation of the workpiece, further shortening the time required for the measurement process. The first distance sensor 31 can also be used to measure the outer diameter, inner diameter, and roundness of the surface machined by the cutting insert 4. Furthermore, the second distance sensor 32 can measure the axial positions of the step portion and the hole bottom portion of the cutting insert 4 .

[0036] The imaging device 5 is provided in the head unit 7 of the tool body 2. The imaging device 5 is arranged on the other side Dj2 in the axial direction Dj with respect to the sensor section 3. The imaging device 5 includes a camera 51. The camera 51 is, for example, a waterproof CMOS image sensor or a CCD image sensor. The camera 51 is fixed to the holder member 70. The camera 51 is arranged so as to be able to photograph the outside of the tool body 2 in the radial direction Dr. The camera 51 photographs the machined surface facing inward in the radial direction Dr, that is, the so-called inner diameter surface, of the workpiece machined by the cutting insert 4.

[0037] The lighting device 6 is provided in the head unit 7 of the tool body 2. The lighting device 6 is disposed on the other side Dj2 in the axial direction Dj of the camera 51 of the imaging device 5. The lighting device 6 includes a light source 61 that illuminates the machined surface photographed by the camera 51. The light source 61 is, for example, a light-emitting element such as an LED.

[0038] The turning tool 1 includes a tool control unit 81, a communication unit 82, and a power supply module 83. In this embodiment, the tool control unit 81 is, in terms of hardware, a control board housed inside the tool body 2, for example. The tool control unit 81 is a computer including a CPU (Central Processing Unit), a memory, etc. Control programs for controlling the operations of the first distance sensor 31, the second distance sensor 32, the camera 51, and the light source 61 are stored in advance in the memory (not shown) of the tool control unit 81.

[0039] The tool control unit 81 outputs control signals to the first distance sensor 31, the second distance sensor 32, the camera 51, and the light source 61 to control the operation of the first distance sensor 31, the second distance sensor 32, the camera 51, and the light source 61 based on instructions from the measuring device main body 100 described later.

[0040] The tool control unit 81 includes signal conversion units 35A and 35B that convert analog output signals indicating voltage values ​​output in accordance with the detection results (distances) of the first distance sensor 31 and the second distance sensor 32 into digital signals. The signal conversion units 35A and 35B are composed of converters. The signal conversion unit 35A outputs, at predetermined time intervals (sampling intervals), the average value of the output signal from the first distance sensor 31 within the time interval (sampling interval) as a detection value. The signal conversion unit 35B outputs, at predetermined time intervals, the average value of the output signal from the second distance sensor 32 within the time interval (sampling interval) as a detection value.

[0041] The communication unit 82 is capable of wireless communication with the outside. In terms of hardware, the communication unit 82 is a communication module mounted on a control board constituting the tool control unit 81. The communication unit 82 is capable of wireless communication with the measuring device main body 100 via a wireless communication network such as a wireless LAN, Wi-Fi (registered trademark), or BLUETOOTH (registered trademark). The communication unit 82 receives control signals output from the measuring device main body 100 for controlling the operation of the first distance sensor 31, the second distance sensor 32, the camera 51, and the light source 61. The communication unit 82 transmits detection values ​​from the signal conversion units 35A and 35B, image data captured by the camera 51, and the like to the measuring device main body 100. The communication unit 82 also transmits the remaining charge (battery voltage) of the power supply module 83 to the measuring device main body 100.

[0042] The power supply module 83 supplies power to the tool control unit 81, the first distance sensor 31, the second distance sensor 32, the camera 51, and the light source 61. The power supply module 83 is a primary battery (battery) such as a manganese dry battery or an alkaline dry battery. The power supply module 83 may be configured to charge a secondary battery such as a lithium-ion battery with electricity from a power generation element such as a piezoelectric vibration sensor that generates electricity using vibrations generated in the tool body 2 during cutting, or may be configured to charge such a secondary battery with electricity supplied contactlessly or contactlessly from an external power source.

[0043] <Measuring Device Main Body> Fig. 2 is a functional block diagram of the measuring device main body 100. The measuring device main body 100, which constitutes part of the measuring device M, is a computer device such as a personal computer, a tablet terminal, or a smartphone. In terms of hardware, the measuring device main body 100 includes a CPU (Central Processing Unit), memory, a storage device, and the like. The measuring device main body 100 is used when processing a workpiece with a turning tool 1. The measuring device main body 100 of this embodiment measures the diameter of the workpiece that has been cut by rotating relatively to the turning tool 1 around a central axis O.

[0044] When a workpiece is machined by the turning tool 1 based on a machining program stored in the machine tool, the measuring device main body 100 controls the operation of the first distance sensor 31, the second distance sensor 32, the camera 51, and the light source 61 of the turning tool 1 based on commands from the machine tool. Based on commands from the machine tool, the measuring device main body 100 measures the dimensions of the workpiece using the first distance sensor 31 and the second distance sensor 32, and photographs the machined surface using the camera 51. Note that the following description of the measuring device main body 100 will focus on measuring the dimension of the workpiece in the radial direction using the first distance sensor 31, and will omit descriptions of measuring the dimension of the workpiece in the axial direction using the second distance sensor 32 and photographing the machined surface using the camera 51 as appropriate.

[0045] The measuring device main body 100 includes a detection control unit 101, an acquisition unit 103, a calculation unit 105, and a result output unit 107, which are implemented by the CPU executing a program stored in the device in advance. The detection control unit 101 controls the operation of a machine tool (not shown) and the turning tool 1 when measuring the dimensions of the machined workpiece after the tool main body 2 has finished machining the workpiece. When measuring the dimensions of the workpiece, the detection control unit 101 rotates the workpiece held by the machine tool around the central axis O of the workpiece. While rotating the workpiece around the central axis O of the workpiece, the detection control unit 101 causes the sensor unit 3 to detect the distance to the workpiece.

[0046] In this embodiment, the detection control unit 101 detects the workpiece for, for example, 150 min. －１More than 1500min －１ The workpiece is rotated at the following predetermined rotation speed. When measuring the dimensions of the workpiece, the rotation speed of the workpiece is 250 min －１ More than 1200min －１ It is more preferable that the rotation speed of the workpiece when measuring the dimensions of the workpiece is 300 min －１ Over 600 min －１ It is particularly preferable that the following is satisfied. When measuring the dimensions of the workpiece, the influence of the electrical runout phenomenon of the workpiece is suppressed by detecting the distance to the machined surface of the workpiece with the first distance sensor 31 while rotating the workpiece at a rotational speed within the above range. If the workpiece is rotated at a rotational speed below the lower limit of the above range when measuring the dimensions of the workpiece, the influence of the electrical runout phenomenon of the workpiece may not be sufficiently suppressed. Furthermore, if the workpiece is rotated at a rotational speed above the upper limit of the above range when measuring the dimensions of the workpiece, mechanical vibrations of the machine tool may increase, which may adversely affect the dimensional measurement of the workpiece.

[0047] The acquisition unit 103 is capable of wireless communication with the communication unit 82 via wireless LAN, Wi-Fi (registered trademark), BLUETOOTH (registered trademark), or the like. The acquisition unit 103 acquires detection values ​​output from the signal conversion units 35A and 35B of the sensor unit 3. The acquisition unit 103 acquires detection values ​​output from the sensor unit 3 within a predetermined time period. The first distance sensor 31 and the second distance sensor 32 of the sensor unit 3 output voltages (analog output signals) corresponding to the detection results (distances) of the distances to the machining surface of the workpiece. The analog output signals output from the first distance sensor 31 and the second distance sensor 32 are converted into digital signals by the signal conversion units 35A and 35B. The signal conversion units 35A and 35B output digital signals obtained by converting the analog output signals output from the first distance sensor 31 and the second distance sensor 32 at predetermined time intervals. The signal conversion units 35A and 35B output, at predetermined time intervals, the average value of the analog output signals from each of the first distance sensor 31 and the second distance sensor 32 within that time interval as the detection value. In other words, the acquisition unit 103 acquires, as the detection value, the average value of the analog output signals from each of the first distance sensor 31 and the second distance sensor 32 of the sensor unit 3 within the predetermined time interval. Here, the time interval can be set to, for example, 0.125 seconds.

[0048] The acquisition unit 103 acquires the detection value output from the signal conversion unit 35A of the sensor unit 3 for a specified time period set so that the workpiece rotated around the central axis O by the machine tool rotates, for example, 5 to 50 times. The specified time period during which the acquisition unit 103 acquires the detection value output from the sensor unit 3 is determined by the rotation speed of the workpiece (rotation speed [min －１]). It is more preferable that the acquisition unit 103 acquires the detection values ​​output from the signal conversion unit 35A for a specified time set so that the workpiece rotates, for example, 10 to 20 times. If the rotation count of the workpiece is less than the lower limit of the above range, the number of detection values ​​from the sensor unit 3 that can be acquired by the acquisition unit 103 will be reduced, and the effects of the electrical runout phenomenon may not be sufficiently suppressed. Furthermore, if the rotation count of the workpiece is greater than the upper limit of the above range, the time required for the acquisition unit 103 to detect multiple detection values ​​will be longer.

[0049] The calculation unit 105 calculates the average value of the plurality of detection values ​​acquired by the acquisition unit 103. The calculation unit 105 calculates the average value of the plurality of detection values ​​acquired by the acquisition unit 103 during a specified time period.

[0050] The result output unit 107 outputs the measurement results of the workpiece based on the average value of the detection values ​​calculated by the calculation unit 105. The result output unit 107 calculates the radial dimension of the workpiece from the calculated distance to the machined surface of the workpiece. The result output unit 107 displays information related to the calculated dimensional measurement results of the workpiece on a display device such as a monitor. The result output unit 107 may determine whether the machining by the machine tool is good or bad based on the dimensional measurement results of the workpiece, and display the determination results, etc.

[0051] <Dimensional measurement method> Next, a description will be given of a dimensional measurement method in the turning tool system 10 described above. Fig. 3 is a flowchart showing the flow of a dimensional measurement method according to one embodiment of the present invention. As shown in Fig. 3, the dimensional measurement method in the turning tool system 10 includes a machining step S1, a distance detection step S2, a detected value acquisition step S3, an average value calculation step S4, and a measurement result output step S5.

[0052] 4A and 4B are diagrams showing machining steps according to one embodiment of the present invention. As shown in FIGS. 4A and 4B , the workpiece W according to this embodiment has a stepped through hole 200. The through hole 200 has a stepped surface 203, a large-diameter portion 201 on one axial side of the stepped surface 203, and a small-diameter portion 202 on the other axial side of the stepped surface 203. In this embodiment, the turning tool 1 is used to perform finishing (so-called internal diameter machining) of the large-diameter portion 201 and the stepped surface 203 of the through hole 200.

[0053] In the machining step S1, as shown in Fig. 4A, the inner peripheral surface of the large diameter portion 201 is machined. In this step, the cutting blade 42 is brought into contact with the inner peripheral surface of the large diameter portion 201 of the workpiece W and moved in the axial direction while the workpiece W is rotated around the main axis O. Furthermore, in the machining step S1, as shown in Fig. 4B, the step surface 203 is machined. In this step, the cutting blade 42 is moved in the radial direction while the workpiece W continues to rotate around the main axis O, to machine the step surface 203.

[0054] After the machining step S1, a distance detection step S2 is carried out. In the distance detection step S2, the first distance sensor 31 is used to obtain detection values ​​corresponding to the respective distances from the workpiece W.

[0055] 5 shows a state in which the first distance sensor 31 detects the distance in the radial direction of the workpiece in the distance detection step S2. In the distance detection step S2, first, the tip surface 31a of the first distance sensor 31 is made to face the inner peripheral surface (machined surface) of the large diameter portion 201. Next, the workpiece held by the machine tool is rotated around the central axis (main axis) O of the workpiece. The detection control unit 101 detects the distance to the inner peripheral surface of the large diameter portion 201 of the workpiece W with the first distance sensor 31 while rotating the workpiece W around the central axis O of the workpiece W. At this time, the detection control unit 101 detects the distance to the inner peripheral surface of the large diameter portion 201 of the workpiece W by the first distance sensor 31. －１ More than 1500min －１ Rotate at the following specified rotation speed.

[0056] The first distance sensor 31 outputs an analog output signal (voltage value) corresponding to the distance to the inner peripheral surface of the large diameter portion 201 of the workpiece W. The analog output signal output from the first distance sensor 31 is converted into a digital signal by the signal conversion unit 35A. The signal conversion unit 35A outputs, at each preset time interval, the average value of the analog output signal from the first distance sensor 31 within that time interval as a detection value.

[0057] After the distance detection step S2, a detection value acquisition step S3 is carried out. In the detection value acquisition step S3, the acquisition unit 103 acquires the detection values ​​output from the signal conversion unit 35A. The acquisition unit 103 acquires the plurality of detection values ​​output at time intervals within a predetermined specified time. The acquisition unit 103 acquires the detection values ​​output from the signal conversion unit 35A for a specified time set so that the workpiece W makes, for example, 10 rotations.

[0058] After the detection value acquisition step S3, an average value calculation step S4 is performed. In the average value calculation step S4, the calculation unit 105 calculates the average value of the multiple detection values ​​acquired in step S3. The calculation unit 105 calculates the average value of the radial distances from the first distance sensor 31 to the machined surface of the workpiece W at multiple locations around the central axis O of the workpiece W.

[0059] After the average value calculation step S4, a measurement result output step S5 is carried out. In the measurement result output step S5, the result output unit 107 outputs the measurement result of the workpiece W based on the average value of the detection values ​​calculated in step S4. The result output unit 107 calculates the radial dimension of the workpiece W from the calculated distance to the machined surface of the workpiece W. The result output unit 107 may display information related to the calculated measurement results of the dimensions of the workpiece on a display device such as a monitor.

[0060] In addition, steps S2 to S5 as described above may be performed in the same manner at multiple positions on the workpiece W that have the same inner diameter by moving the first distance sensor 31 in the direction of the center axis O of the workpiece W.

[0061] [Effects of the Present Embodiment] According to the dimension measuring device M, turning tool system 10, and dimension measuring method of the present embodiment described above, by acquiring multiple detection values ​​that are average values ​​of the outputs of the first distance sensor 3131 while rotating the workpiece and then averaging the multiple acquired detection values, it is possible to efficiently measure the dimension of the workpiece in the radial direction while suppressing the influence of the electrical runout phenomenon. As a result, it is possible to efficiently and accurately measure the dimension of the workpiece in the radial direction while rotating the workpiece.

[0062] In this embodiment, the workpiece is cut for 150 min. －１ More than 1500min －１ The workpiece is rotated at the following predetermined rotational speed while the radial dimension of the workpiece is measured. This allows the number of detected values ​​to be averaged in a short time to be increased. Therefore, the radial dimension of the workpiece can be measured more efficiently and with higher accuracy.

[0063] In this embodiment, the detected values ​​are acquired while rotating the workpiece five or more times within a specified time. This increases the number of detected values ​​to be used for calculating the average value. This allows for more accurate measurement of the radial dimension of the workpiece.

[0064] In this embodiment, the sensor unit 3 is attached to the turning tool 1. This allows the sensor unit 3 attached to the turning tool 1 to efficiently measure the radial dimension of the workpiece machined by the turning tool 1.

[0065] In this embodiment, the direction in which the dimension measuring device M and the turning tool system process the workpiece and perform dimension measurement is the radial direction of the central axis O. However, the direction in which the dimension measuring device M and the turning tool system process the workpiece and perform dimension measurement may be the axial direction of the central axis O. In this case, the turning tool 1 cuts the end face of the workpiece W that rotates around the central axis O, the end face facing the axial direction. In addition, the sensor unit 3 detects the distance to the end face of the workpiece W that faces the axial direction.

[0066] In this embodiment, the signal converter 35A outputs the average value of the output signal of the first distance sensor 31 within each predetermined time interval as the detection value. However, the output signal of the first distance sensor 31 may be output as the detection value without averaging. That is, the signal converter 35A may output the detection value based on the output signal of the first distance sensor 31. In this case, a dimension measuring device that achieves the same effect by averaging the detection value in the calculation unit 105 can be configured. Even in this case, the signal converter 35A outputs the detection value at each predetermined time interval. Here, the time interval at which the signal converter 35A outputs the detection value is the sampling period of the converter of the signal converter 35A. That is, the signal converter 35A either outputs the output signal of the distance sensor as the detection value or averages the output signal and outputs it as the detection value at each sampling period of the converter.

[0067] (Modification of the embodiment) In the above embodiment, when the dimension measuring device M measures the dimension of the workpiece in the radial direction, calibration may be performed according to the material of the workpiece, etc. In this case, the distance detection error of the first distance sensor 31 due to the influence of the material of the workpiece, etc. may be determined in advance by experiment, etc., and the distance detection result of the first distance sensor 31 may be calibrated based on the determined result. Furthermore, in the above embodiment, the sensor unit 3 is attached to the turning tool 1, but this is not limited to this. The sensor unit 3 may be provided independently from the turning tool 1. In this case, the sensor unit 3 may be provided, for example, on the machine tool side.

[0068] [Other Configurations Included in the Present Invention] The present invention is not limited to the above-described embodiments, and the configurations (components) described in the above-described embodiments, modifications, and notes may be combined within the scope of the present invention, and additions, omissions, substitutions, and other modifications of the configurations are possible. Furthermore, the present invention is not limited to the above-described embodiments, but is limited only by the claims.

[0069] For example, in the above-described embodiment, a turning tool that rotates a workpiece to perform cutting has been described as an example of a cutting tool included in the cutting tool system. However, the turning tool is not limited to the turning tool of this embodiment as long as it presses a cutting insert against the workpiece to perform cutting. The cutting tool may also be a rotating tool that rotates itself, such as a drill, an end mill, or a milling machine.

[0070] (Example) The configuration described in the above embodiment was verified, and the results are shown below. First, the occurrence of electrical runout was confirmed. To do this, after machining the workpiece, the inner diameter was measured using a dial gauge, and it was confirmed in advance that the variation in diameter (mechanical runout) at multiple positions in the circumferential direction was within 0.5 μm. Then, the workpiece was rotated around the central axis O by 5° increments, and the first distance sensor 31 detected the distance to the inner surface of the large diameter portion 201 of the workpiece at each phase. When detecting the distance using the first distance sensor 31, the workpiece was not rotated but was fixed at each phase.

[0071] Figure 6 shows the variation in the detected distance to the machined surface of the workpiece in the radial direction due to the electrical runout phenomenon. As a result, as shown in Figure 6, it was confirmed that the detected distance varies depending on the phase of the workpiece, with a difference of 8 μm between the minimum and maximum values. Since the variation is larger than the measurement results using a dial gauge, it can be inferred that this is due to the electrical runout phenomenon.

[0072] Next, while the workpiece was rotated around the central axis O by the machine tool, the distance to the inner peripheral surface of the large diameter portion 201 of the workpiece was detected by the first distance sensor 31. －１ , 300 min －１ , 600 min －１ , 1200 min －１ The rotation was performed at four different rotation speeds, and distance detection was performed by the first distance sensor 31 at time intervals of 0.125 seconds.

[0073] 7 is a diagram showing the variation in the detected distance to the machined surface of the workpiece in the radial direction when the rotation speed of the workpiece is changed. As a result, as shown in FIG. －１ When the workpiece is rotated at a rotation speed of 300 min, the detected distance varies. －１ , 600 min －１ , 1200 min －１ When the workpiece was rotated at this rotational speed, it was confirmed that the variation in detection distance was equivalent to the measurement results using a dial gauge.

[0074] Next, the workpiece is rotated around the central axis O by the machine tool for 300 minutes. －１ The workpiece was rotated at 2.5, 5, and 10 revolutions, and the first distance sensor 31 detected the distance to the inner surface of the workpiece. The number of revolutions of the workpiece was set to three: 2.5, 5, and 10 revolutions. The average value of the detected values ​​output from the signal converter 35A was calculated until the workpiece reached 2.5, 5, and 10 revolutions. Furthermore, the same distance detection and calculation of the average detected values ​​were repeated 10 times for each of the 2.5, 5, and 10 revolutions. Figure 8 shows the average detected values ​​to the machined surface of the workpiece in the radial direction when the number of revolutions of the workpiece was varied. As a result, as shown in Figure 8, it was confirmed that the greater the number of revolutions of the workpiece, the smaller the variation in the average detected values ​​when the first distance sensor 31 detected the distance to the inner surface of the workpiece.

[0075] Furthermore, the workpiece is rotated around the central axis O by a machine tool for 60 minutes. －１ , 300 min －１ , 600 min －１ , 1200 min －１ The workpiece was rotated at four different rotational speeds, and the distance detection and calculation of the average of the detected values ​​were repeated in the same manner as above. Figure 9 shows the variation (maximum - minimum) of the average of the detected values ​​up to the machined surface of the workpiece in the radial direction when the radial dimension of the workpiece was repeatedly measured 10 times. As a result, as shown in Figure 9, －１ , 600 min －１, 1200 min －１ In the case of the first distance sensor 31, it was confirmed that the variation in the detected value becomes small if the number of rotations of the workpiece is 5 or more when the first distance sensor 31 detects the distance to the inner peripheral surface of the workpiece. －１ In this case, 300 min －１ , 600 min －１ , 1200 min －１ Compared to the case of (1), the variation in the detected values ​​is large even if the number of rotations of the workpiece increases.

[0076] The present invention may be combined with the various configurations described in the above-described embodiments and modifications, and may also include additions, omissions, substitutions, and other modifications of the configurations, without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the above-described embodiments, but is limited only by the claims.

[0077] The dimensions of the workpiece in one direction can be measured efficiently and with high accuracy.

[0078] REFERENCE SIGNS LIST 1 Turning tool (cutting tool) 2 Tool body 3 Sensor unit 4 Cutting insert 5 Imaging device 6 Lighting device 7 Head unit 10 Turning tool system (cutting tool system) 21 Shank portion 22 Head portion 23 Protrusion 23d Base 31 First distance sensor 31a Tip surface 32 Second distance sensor 35A, 35B Signal conversion unit 41 Cartridge 42 Cutting edge 51 Camera 61 Light source 70 Holder member 81 Tool control unit 82 Communication unit 83 Power supply module 100 Measuring device body 101 Detection control unit 103 Acquisition unit 105 Calculation unit 107 Result output unit 200 Through hole 201 Large diameter portion 202 Small diameter portion 203 Step surface Dj Axial direction Dj1 One side Dj2 Other side Dr Radial direction Dr1: First side Dr2: Second side J: Tool axis M: Dimension measuring device O: Center axis, spindle S1: Machining process S2: Distance detection process S3: Detection value acquisition process S4: Average value calculation process S5: Measurement result output process W: Workpiece

Claims

1. A dimensional measuring device for measuring a dimension in one direction of a workpiece that has been machined by rotating it relative to a cutting tool around a central axis, comprising: a sensor unit that detects a distance to a machined surface of the workpiece in the one direction of the workpiece; and a measuring device main body that measures the dimension of the workpiece in the one direction based on the distance detected by the sensor unit, wherein the sensor unit includes: a distance sensor using an eddy current sensor; and a signal conversion unit that outputs a detection value based on an output signal of the distance sensor at each preset time interval, and the measuring device main body comprises: a detection control unit that causes the sensor unit to detect the distance to the workpiece while rotating the workpiece around the central axis; an acquisition unit that acquires a plurality of the detection values ​​output from the sensor unit at each preset time interval; a calculation unit that calculates an average value of the plurality of detection values ​​acquired by the acquisition unit; and a result output unit that outputs a measurement result of the workpiece based on the average value of the detection values ​​calculated by the calculation unit.

2. The dimension measuring device according to claim 1, wherein the signal conversion section outputs, at each preset time interval, an average value of the output signal of the distance sensor within the time interval as a detection value.

3. The detection control unit detects the workpiece for 150 min. －１ More than 1500min －１ The dimension measuring device according to claim 1 , wherein the device is rotated at a predetermined rotation speed below a predetermined rotation speed.

4. The dimension measuring device according to any one of claims 1 to 3, wherein the acquisition unit acquires the detection value while rotating the workpiece five or more revolutions within the specified time.

5. A cutting tool system comprising: a cutting tool having a tool body extending along a tool axis and having a seat at a tip portion, and a cutting insert removably attached to the seat; and the dimension measuring device according to any one of claims 1 to 3.

6. The cutting tool system according to claim 5, wherein the sensor unit is attached to the cutting tool.

7. A dimensional measurement method for measuring a dimension in one direction of a workpiece that has been machined by rotating it relative to a cutting tool around a central axis, comprising the steps of: detecting a distance to the workpiece with a distance sensor using an eddy current sensor while rotating the workpiece around the central axis, and outputting, at each preset time interval, an average value of the outputs of the distance sensor within the time interval as a detection value; acquiring a plurality of the detection values ​​that are output at each time interval within a preset specified time; calculating the average value of the acquired detection values; and outputting a measurement result of the workpiece based on the calculated average value of the detection values.

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