State detection system, method, and program

Abstract

A state detection system for a milling tool used for milling, the state detection system being provided with: a milling tool that includes a shaft section having a first end section and a second end section and that is rotatable about a rotation axis of the shaft section; a plurality of sensors attached to the shaft portion and detecting an external force acting on the milling tool; a display device; and a management device. The plurality of sensors detect a first force acting on the milling tool in a first direction along the rotation axis, a second force acting on the milling tool in a direction along a plane with the rotation axis as a normal, and a load torque acting on the milling tool in a direction obstructing rotation of the milling tool. The management device causes the display device to display information based on at least two of the first force, the second force, and the load torque.

Description

Technical Field

[0001] The present disclosure relates to a state detection system, method, and program. Background Art

[0002] In recent years, there has been a demand for a system that detects the state of a milling tool under various milling conditions. Japanese Patent Laid-Open No. 59-142048 (Patent Document 1) discloses a tool abnormality detection device that uses the relationship between the main force component, feed force component, and back force component generated during cutting to detect abnormalities generated in the tool. Japanese Patent Laid-Open No. 58-217247 (Patent Document 2) describes an abnormal phenomenon monitoring method that determines defects by finding the cutting force ratio of the main force component, feed force component, and back force component and the differential coefficient of the force ratio relative to time. Japanese Patent Laid-Open No. 09-076144 (Patent Document 3) describes a processing state monitoring method that monitors the processing state by detecting the load of the X-axis and Y-axis during drilling processing of a machine tool.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 59-142048

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 58-217247

[0007] Patent Document 3: Japanese Patent Application Laid-Open No. 09-076144 Summary of the invention

[0008] The state detection system of a milling tool for milling processing involved in the present disclosure comprises: a milling tool including a shaft portion, the shaft portion having a first end portion provided with a blade portion for cutting a workpiece and a second end portion mounted on a machine tool, the milling tool being able to rotate around the rotation axis of the shaft portion; a plurality of sensors mounted on the shaft portion to detect external forces acting on the milling tool; a display device; and a management device. The plurality of sensors detect a first force acting on the milling tool in a first direction along the rotation axis, a second force acting on the milling tool in a direction along a plane with the rotation axis as a normal, and a load torque acting on the milling tool in a direction that hinders the rotation of the milling tool. The management device displays information based on at least two of the first force, the second force, and the load torque on the display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of the state detection system of the milling tool according to the present embodiment.

[0010] Figure 2 It is a stereogram of a milling tool.

[0011] Figure 3 Viewed from the negative side of the Y axis Figure 2 Figure 2. Milling tool in the drawing.

[0012] Figure 4 Viewed from the positive side of the X axis Figure 2 Figure 2. Milling tool in the drawing.

[0013] Figure 5 Viewed from the positive direction of the Z axis Figure 2 Figure 1. The axis of the middle part.

[0014] Figure 6 Viewed from the positive direction of the Z axis Figure 2 FIG. 106 is a diagram of a free end of the shaft portion 106.

[0015] Figure 7 This is a diagram showing the relationship between the external force Fx, the external force Fy, the external force Fz, and the state of the blade.

[0016] Figure 8 This is a first example of a graph showing the state of a milling tool.

[0017] Fig. 9 This is a second example of a graph showing the state of a milling tool.

[0018] Fig.10 This is a third example of a graph showing the state of a milling tool.

[0019] Fig.11 This is a fourth example of the graph showing the state of the milling tool.

[0020] Fig.12 This is a fifth example of the graph showing the state of the milling tool.

[0021] Fig.13 This is a sixth example of the graph showing the state of the milling tool.

[0022] Fig.14 The relationship between external force, specific cutting resistance and cutting area is explained.

[0023] Fig.15 This is a diagram for explaining the relationship between load torque and cutting area.

[0024] Fig.16 This is a seventh example of the graph showing the state of the milling tool.

[0025] Fig.17 This is an eighth example of the graph showing the state of the milling tool.

[0026] Fig.18It is a flowchart showing the processing procedure of this embodiment.

[0027] Fig.19 It is a graph showing the measurement results of the test for preparing the normal area.

[0028] Fig. 20 is based on Fig.19 A graph showing the measurement results.

[0029] Fig.21 It is a diagram showing an example of setting the normal area in the period Dr2.

[0030] Fig. 22 It is a diagram showing an example of setting the normal area in the period Dr2 and the period Dr3. DETAILED DESCRIPTION

[0031] [Problems to be Solved by the Present Disclosure]

[0032] The object of the present disclosure is to provide a state detection system for detecting the state of a milling tool used for milling processing.

[0033] [Effects of the present disclosure]

[0034] According to the present disclosure, a state detection system can be provided, which can detect the state of a milling tool used for abnormality judgment of the milling tool based on external forces acting in the direction along the rotation axis, external forces acting in the direction along the plane with the rotation axis as the normal, and load torque acting in the direction that hinders rotation.

[0035] [Description of Embodiments of the Present Disclosure]

[0036] First, embodiments of the present disclosure will be described by way of examples.

[0037] (1) The state detection system of a milling tool for milling processing involved in the present disclosure comprises: a milling tool including a shaft portion, the shaft portion having a first end portion provided with a blade portion for cutting a workpiece and a second end portion mounted on a machine tool, the milling tool being rotatable around a rotation axis of the shaft portion; a plurality of sensors mounted on the shaft portion for detecting external forces acting on the milling tool; a display device; and a management device. The plurality of sensors detect a first force acting on the milling tool in a first direction along the rotation axis, a second force acting on the milling tool in a direction along a plane with the rotation axis as a normal, and a load torque acting on the milling tool in a direction that hinders the rotation of the milling tool. The management device causes first information based on at least two of the first force, the second force, and the load torque to be displayed on the display device.

[0038] (2) In the state detection system according to (1) above, the management device displays the first information using a graph.

[0039] (3) In the state detection system according to (1) or (2), the management device displays the first information on the display device and further displays second information based on at least two of the first force, the second force, and the load torque on the display device. The second information is different from the first information.

[0040] (4) In the state detection system according to (1) above, the first information is information based on a ratio of the first force to the load torque and a ratio of the second force to the load torque.

[0041] (5) Based on the state detection system involved in any one of the above (1) to (4), the multiple sensors include: a first strain sensor, a second strain sensor and a third strain sensor, which detect the strain in the first direction and are installed on the shaft; and a fourth strain sensor, which detects the strain in the circumferential direction of the shaft and is installed on the shaft.

[0042] (6) The method involved in the present invention is a method for detecting the state of a milling tool used for milling processing. The milling tool includes a shaft portion, the shaft portion having a first end portion provided with a blade portion for cutting a workpiece and a second end portion mounted on a machine tool, the milling tool can rotate around the rotation axis of the shaft portion, and a plurality of sensors for detecting external forces acting on the milling tool are mounted on the shaft portion. The method includes the following steps: using the detection values ​​of the plurality of sensors to obtain a first force acting in a first direction along the rotation axis; using the detection values ​​of the plurality of sensors to obtain a second force acting in a direction along a plane with the rotation axis as a normal; using the detection values ​​of the plurality of sensors to obtain a load torque acting in a direction that hinders the rotation of the milling tool; and displaying first information based on at least two of the first force, the second force, and the load torque.

[0043] (7) The program involved in the present disclosure is a program for detecting the state of a milling tool used for milling processing. The milling tool includes a shaft portion, the shaft portion having a first end portion provided with a blade portion for cutting a workpiece and a second end portion mounted on a machine tool, the milling tool can rotate around the rotation axis of the shaft portion, and a plurality of sensors for detecting external forces acting on the milling tool are mounted on the shaft portion. The program causes a computer to execute the following steps: using the detection values ​​of the plurality of sensors to obtain a first force acting in a first direction along the rotation axis; obtaining a second force acting in a direction along a plane with the rotation axis as a normal; obtaining a load torque acting in a direction that hinders the rotation of the milling tool; and displaying first information based on at least two of the first force, the second force, and the load torque.

[0044] [Details of the embodiments of the present disclosure]

[0045] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the same reference numerals are given to the same or corresponding parts in the drawings, and their description will not be repeated.

[0046] (Overview of the Status Detection System)

[0047] Figure 1 1 is a schematic diagram of a state detection system 100 for a milling tool 50 according to the present embodiment. Figure 1 The state detection system 100 of the milling tool 50 in the embodiment can be applied to the milling tool of a machine tool such as a machining center or a milling machine. The state detection system 100 includes a management device 10 and a machine tool 70. The machine tool 70 includes a motor 20 and a milling tool 50.

[0048] The milling tool 50 is a milling tool for cutting a fixed object to be cut (workpiece), and is a milling tool used in a machine tool such as a machining center or a milling machine. The milling tool 50 of the present embodiment is an end mill. It should be noted that the milling tool 50 may also be a milling tool other than an end mill, for example, a drill or a milling cutter. The milling tool 50 includes a shaft portion 106 formed with a blade. The milling tool 50 is mounted on the machine tool 70 via a tool holder 30 that holds the shaft portion 106. That is, a blade is provided at the end of the shaft portion 106 on the lower side in the vertical direction, and the end of the shaft portion 106 on the upper side in the vertical direction is mounted on the tool holder 30 on the machine tool 70 side. The end of the shaft portion 106 on the lower side in the vertical direction is an example of the "first end" in the present disclosure, and the end of the shaft portion 106 on the upper side in the vertical direction is an example of the "second end" in the present disclosure. In addition, the tool holder 30 may be formed at the end of the shaft portion 106 on the upper side in the vertical direction. In this case, the milling tool 50 includes the tool holder 30 .

[0049] The tool holder 30 is connected to the shaft portion 106 and supports the shaft portion 106 from above in the vertical direction. The tool holder 30 has a conical end portion on the positive direction side of the Z axis, and the conical end portion is mounted on the machine tool 70. The motor 20 included in the machine tool 70 rotates the milling tool 50 integrally. In other words, the motor 20 drives the milling tool 50 to rotate. The motor 20 is, for example, a servo motor.

[0050] In this embodiment, the milling tool 50 as an end mill has at least one blade. The motor 20 drives the milling tool 50 to rotate, so that the blade of the milling tool 50 contacts the surface of the workpiece and cuts the surface of the workpiece. Thus, the shape of the workpiece is formed into a shape desired by the user.

[0051] The strain sensors N1 to N3 and S4 are mounted on the shaft 106. The strain sensors N1 to N3 and S4 are sensors capable of detecting strain generated in the shaft 106, and are, for example, strain gauges composed of a bridge circuit. The strain sensors N1 to N3 and S4 are wirelessly connected to the management device 10, and the values ​​detected by each are sent to the management device 10.

[0052] The management device 10 detects the state of the milling tool 50 using the detection values ​​of the strain sensors N1 to N3 and the strain sensor S4 installed on the milling tool 50. The management device 10 includes a communication device 210, a CPU (Central Processing Unit) 220 as a control device, a storage device 230, an input / output interface (I / F) 240, a display device 40, and an input device 270.

[0053] The communication device 210, the CPU 220, the storage device 230, and the input / output I / F 240 are connected to a common bus 250 and are configured to be able to transmit and receive signals to each other. The display device 260 and the input device 270 are connected to the input / output I / F 240 by wire or wirelessly.

[0054] The communication device 210 is a wireless communication device that wirelessly acquires the detection values ​​of the strain sensors N1 to N3 and S4 mounted on the tool holder 30. The CPU 220 executes a program stored in the storage device 230 to process the detection values ​​of the strain sensors N1 to N3 and S4 acquired by the communication device 210, thereby detecting the state of the milling tool 50.

[0055] The storage device 230 includes a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and a large-capacity storage device such as a HDD (Hard Disc Drive) or an SSD (Solid State Disk). The storage device 230 is used as a buffer during the processing of the CPU 220, and is used to store the program executed by the CPU 220, the detection values ​​of the strain sensors N1 to N3, and the strain sensor S4, and / or the calculation results of the CPU 220.

[0056] The input device 270 is a pointing device such as a keyboard, a mouse, a trackball or a touch panel, and receives operation signals from the user. The display device 40 is typically a liquid crystal panel or an organic EL (Electro Luminescence) panel, and displays the calculation results of the CPU 220 and the information stored in the storage device 230 to the user. In this embodiment, the management device 10 displays information based on the detection values ​​of the strain sensors N1 to N3 and the strain sensor S4 on the display device 40, thereby allowing the user to recognize the state of the milling tool 50.

[0057] The input / output I / F 240 is an interface for connecting the display device 40 and the input device 270. The input / output I / F 240 receives a user operation signal from the input device 270 and outputs information for notifying the user to the display device 40.

[0058] (Details of strain sensor)

[0059] Figure 2 is a perspective view of a milling tool 50 . Figure 2 The Z axis shown is the rotation axis of the milling tool 50. That is, the milling tool 50 is driven by the motor 20 and rotates around the Z axis. The milling tool 50 rotates in a clockwise rotation direction Rd when viewed from the positive direction side of the Z axis. The X axis and the Y axis that are perpendicular to each other are axes that are also perpendicular to the Z axis. In the following description, the positive direction of the Z axis in each figure is sometimes referred to as the upper surface side, and the negative direction is referred to as the lower surface side.

[0060] As described above, the rotating milling tool 50 contacts the surface of the workpiece and cuts off the surface of the workpiece. By making the milling tool 50 contact the workpiece, an external force is applied to the milling tool 50. Figure 2 As shown, the external forces acting on the milling tool 50 due to the contact between the milling tool 50 and the workpiece include external forces Fx, Fy, and Fz acting in the X-axis direction, the Y-axis direction, and the Z-axis direction, respectively, and a load torque Mz acting in a direction that hinders the rotation of the milling tool 50. The load torque Mz acts in a direction that hinders the rotation of the milling tool 50, and therefore acts in a rotation direction opposite to the rotation direction Rd of the milling tool 50. That is, when viewed from the positive direction side of the Z-axis, the load torque Mz acts counterclockwise.

[0061] exist Figure 2 In the figure, the direction of the external force Fx is shown as the positive direction of the X axis, the direction of the external force Fy is shown as the negative direction of the Y axis, and the direction of the external force Fz is shown as the negative direction of the Z axis. Figure 2 As shown in FIG. 1 , different hatching lines are marked on the external force Fx, the external force Fy, and the external force Fz. It should be noted that the external force Fx, the external force Fy, and the external force Fz sometimes also move in the same direction as the external force Fx, the external force Fy, and the external force Fz. Figure 2 The direction opposite to that shown works.

[0062] Strain sensors N1 to N3 and strain sensor S4 are arranged on the same XY plane. Strain sensors N1 to N3 and strain sensor S4 are arranged on the surface of the shaft portion 106 at intervals of 90° in the circumferential direction of the shaft portion 106. That is, when the shaft portion 106 is observed from the negative direction side of the Y axis, the strain sensor N1 and the strain sensor N3 are arranged line-symmetrically with respect to the Z axis. In addition, when the shaft portion 106 is observed from the positive direction side of the X axis, the strain sensor N2 and the strain sensor S4 are arranged line-symmetrically with respect to the Z axis.

[0063] The strain sensors N1 to N3 have measurement sensitivity to the strain in the Z-axis direction of the shaft portion 106. On the other hand, the strain sensor S4 has measurement sensitivity to the strain in the circumferential direction of the shaft portion 106. Hereinafter, a method for detecting the external force Fx, the external force Fy, the external force Fz, and the load torque Mz using the strain sensors N1 to N3 and the strain sensor S4 will be described.

[0064] Figure 3 Viewed from the negative side of the Y axis Figure 2 Figure 50 of the milling tool. Figure 3 , the external force Fx and the external force Fz are shown in FIG. The shaft portion 106 is a cantilever beam having a fixed end on the positive direction side of the Z axis and a free end on the negative direction side of the Z axis where a blade portion is formed. Therefore, a bending moment is generated by the external force Fx acting on the milling tool 50. The magnitude of the bending moment is determined by the magnitude of the external force Fx and the distance D1 between the strain sensors N1 and N3 in the Z axis direction and the free end of the shaft portion 106.

[0065] The bending moment deforms the shaft 106 to form a convex shape toward the negative direction of the X-axis, and the shaft 106 is slightly warped and bent. That is, the shaft 106 is bent by the external force Fx. The bending moment generates a compressive stress Cx and a tensile stress Tx as bending stress according to the cross-sectional modulus of the shaft 106. Figure 3 In FIG. 1 , the compressive stress Cx and the tensile stress Tx generated by the external force Fx are marked with the same hatching lines as the external force Fx.

[0066] The strain sensor N1 disposed on the positive side of the X-axis of the shaft portion 106 has measurement sensitivity to the compressive stress Cx. In addition, the strain sensor N1 also has measurement sensitivity to the tensile stress Tz generated by the external force Fz. Figure 3In FIG. 1 , the tensile stress Tz generated by the external force Fz is marked with the same hatching as the external force Fz. Therefore, the strain sensor N1 detects the resultant force of the compressive stress Cx and the tensile stress Tz. In other words, the detection value Dv1 of the strain sensor N1 is the resultant force of the compressive stress Cx and the tensile stress Tz. The strain sensor N1 sends the detection value Dv1 to the management device 10.

[0067] The strain sensor N3, like the strain sensor N1, has a measurement sensitivity to the tensile stress Tz based on the external force Fz, and also has a measurement sensitivity to the tensile stress Tx generated by the external force Fx. Therefore, the detection value Dv3 of the strain sensor N3 is the resultant force of the tensile stress Tx and the tensile stress Tz. The strain sensor N3 sends the detection value Dv3 to the management device 10.

[0068] The management device 10 calculates the respective values ​​of tensile stress Tz, tensile stress Tx, and compressive stress Cx based on the detection value Dv1 indicating the resultant force of compressive stress Cx and tensile stress Tz and the detection value Dv3 indicating the resultant force of tensile stress Tx and tensile stress Tz. The strain sensors N1 and N3 are arranged line-symmetrically with respect to the Z axis on the same XY plane. The compressive stress Cx and tensile stress Tx are bending stresses generated based on the same bending moment, so the compressive stress Cx and tensile stress Tx are stresses of the same magnitude.

[0069] The management device 10 calculates the magnitude of the compressive stress Cx and the tensile stress Tx by calculating the difference between the detection value Dv1 and the detection value Dv3. The magnitude of the compressive stress Cx and the tensile stress Tx varies according to the magnitude of the external force Fx and the bending moment determined by the distance D1. That is, the management device 10 can calculate the magnitude of the external force Fx according to the magnitude of the compressive stress Cx and the tensile stress Tx and the distance D1.

[0070] In addition, after calculating the magnitudes of the compressive stress Cx and the tensile stress Tx, the management device 10 can also calculate the magnitude of the tensile stress Tz by subtracting the magnitude of the compressive stress Cx from the detection value Dv1 or subtracting the magnitude of the tensile stress Tx from the detection value Dv3. The tensile stress Tz is a force generated by the external force Fz, so the management device 10 can calculate the magnitude of the external force Fz based on the magnitude of the tensile stress Tz. In this way, the management device 10 calculates the magnitude of the external force Fx and the magnitude of the external force Fz based on the detection values ​​Dv1 and Dv3 of the strain sensor N1 and the strain sensor N3.

[0071] Figure 4 Viewed from the positive side of the X axis Figure 2 Figure 50 of the milling tool. Figure 42 shows the external force Fy and the external force Fz generated by the contact between the milling tool 50 and the workpiece. As described above, the strain sensor N2 has measurement sensitivity in the Z-axis direction.

[0072] Similar to the case where the shaft 106 is convexed toward the negative direction of the X-axis by the bending moment generated by the external force Fx, the external force Fy generates a bending moment that causes the shaft 106 to be convex toward the positive direction of the Y-axis. That is, the strain sensor N2 disposed on the positive direction side of the Y-axis of the shaft 106 detects the resultant force of the tensile stress Ty and the tensile stress Tz as the detection value Dv2.

[0073] As in Figure 3 As described in , the management device 10 calculates the magnitude of the tensile stress Tz based on the detection value Dv1 of the strain sensor N1 and the detection value Dv3 of the strain sensor N3. The management device 10 can calculate the magnitude of the tensile stress Ty by subtracting the tensile stress Tz from the detection value Dv2. In addition, the management device 10 can calculate the magnitude of the external force Fy based on the magnitude of the tensile stress Ty and the distance D1, similarly to the calculation of the magnitude of the external force Fx.

[0074] Figure 5 Viewed from the positive direction of the Z axis Figure 2 FIG. 106 of the shaft portion. Figure 5 , the detection value of the strain sensor S4 is described. The strain sensor S4 has a measurement sensitivity in the circumferential direction of the tool holder 30. Therefore, by making the milling tool 50 contact the workpiece, the load torque Mz acts on the tool holder 30 in the rotation direction opposite to the rotation direction Rd of the milling tool 50 and the tool holder 30. That is, as long as the rotating milling tool 50 contacts the workpiece, the detection value of the strain sensor S4 includes the load torque Mz.

[0075] As described above, the external force Fx and the external force Fy act on the milling tool 50 in contact with the workpiece. The external force Fx and the external force Fy are in the same direction as the load torque Mz along the XY plane, so the detection value of the strain sensor S4 includes at least one of the external force Fx and the external force Fy in addition to the load torque Mz.

[0076] The arrangement of the strain sensor S4 on the XY plane varies according to the rotation angle of the tool holder 30. For example, Figure 5As shown, the strain sensor S4 configured with Ag1 has measurement sensitivity to the external force Fx because the measurement direction of the strain sensor S4 is parallel to the X-axis direction. In addition, the strain sensor S4 configured with Ag2 has measurement sensitivity to the external force Fy because the measurement direction of the strain sensor S4 is parallel to the Y-axis direction. In addition, the strain sensor S4 configured with Ag3 has measurement sensitivity to both the external force Fx and the external force Fy because the measurement direction of the strain sensor S4 intersects both the X-axis direction and the Y-axis direction. The strain sensor S4 detects the combined force of the external force Fx, the external force Fy and the load torque Mz.

[0077] like Figure 3 , Figure 4 As described in , the management device 10 calculates the magnitude of the external force Fx and the magnitude of the external force Fy based on the detection value Dv1 of the strain sensor N1 to the detection value Dv3 of the strain sensor N3. The management device 10 can calculate the load torque Mz by removing the influence of the external force Fx and the external force Fy from the detection value of the strain sensor S4. In this way, in this embodiment, the magnitudes of the external force Fx, the external force Fy, the external force Fz, and the load torque Mz can be calculated by the strain sensors N1 to N3 having measurement sensitivity in the Z-axis direction and the strain sensor S4 having measurement sensitivity in the circumferential direction of the shaft portion 106.

[0078] In addition, in the state detection system 100, the external force Fx, the external force Fy, the external force Fz, and the load torque Mz can be calculated not only by the above method but also by other methods. In one aspect, the state detection system 100 can be composed of six strain sensors, including three strain sensors with measurement sensitivity in the circumferential direction and three strain sensors with measurement sensitivity in the Z-axis direction, or five strain sensors, including three strain sensors with measurement sensitivity in the circumferential direction and two strain sensors with measurement sensitivity in the Z-axis direction. In this way, by increasing the number of strain sensors, the load torque Mz and the like can be directly detected, so in the state detection system 100, the calculation processing performed by the management device 10 can be reduced.

[0079] Figure 6 Viewed from the positive direction of the Z axis Figure 2 In the present embodiment, the milling tool 50 has three blades: blade 6A, blade 6B, and blade 6C. Figure 1 to Figure 5 The external force Fx, the external force Fy, the external force Fz, and the load torque Mz described in 2 are generated when the blade portions 6A to 6C come into contact with the workpieces, respectively.

[0080] That is, the load torque Mz calculated using the strain sensor S4 is the load torque acting on Figure 6The load torque MzA of the blade 6A, the load torque MzB acting on the blade 6B, and the load torque MzC acting on the blade 6C are shown. Each load torque MzA, load torque MzB, and load torque MzC are all forces acting in the same circumferential direction, so the load torque Mz calculated using the strain sensor S4 is a value obtained by summing the absolute values ​​of each load torque MzA, load torque MzB, and load torque MzC.

[0081] On the other hand, the external force Fx and the external force Fy are not the sum of the absolute values ​​of the external forces generated on each blade, but are calculated as the sum of vectors. Therefore, the external forces generated on each blade sometimes cancel each other out. Hereinafter, the resultant force of the external force Fx and the external force Fy is referred to as "external force Fxy". Figure 6 As shown, external force FxyA acts on blade portion 6A, external force FxyB acts on blade portion 6B, and external force FxyC acts on blade portion 6C.

[0082] The external forces Fx and Fy act in the direction along the XY plane, so Figure 6 As shown, the external force Fxy acting on the entire milling tool 50 is the sum of the vectors representing the external force FxyA, the external force FxyB, and the external force FxyC. Therefore, even when the milling tool 50 is in contact with the workpiece, the external forces FxyA to FxyC acting on each blade 6A to 6C cancel each other out, and the external force Fxy acting on the entire milling tool 50 may be "0". In other words, although the external forces FxyA to FxyC act on each blade 6A to 6C, the entire milling tool 50 is sometimes in a state where the external force Fxy does not appear to act.

[0083] It should be noted that the load torque Mz is actually the value obtained by multiplying the component force in the tangential direction of the external force Fxy by the radius of the milling tool 50. Figure 6 For ease of explanation, the arrow extending from the tangential direction is described as the load torque Mz.

[0084] Figure 7 This is a diagram showing the relationship between the external force Fx, the external force Fy, the external force Fz, and the state of the blade. Figure 7 The blade 6A is shown in states St1, St2, and St3, respectively. State St1 is a state where the blade 6A has no problems and can perform cutting properly. State St2 is a state where the blade tip of the blade 6A is worn. State St3 is a state where the blade tip of the blade 6A is damaged. Figure 7 The chipped workpiece 60 is shown in FIG.

[0085] The external force Fx generated by the contact between the workpiece 60 and the blade 6A is determined by the specific cutting resistance Kx and the cutting area. The specific cutting resistance Kx is the resistance in the X-axis direction based on the state of the blade. The specific cutting resistance has different values ​​in each direction of the X-axis, Y-axis, and Z-axis. The cutting area is determined by the cutting depth ap and the feed rate fz.

[0086] like Figure 7 As shown in the lower part of , the external force Fx is the value obtained by multiplying the specific cutting resistance Kx, the cutting depth ap and the feed rate fz. In addition, the external force Fy is also the value obtained by multiplying the specific cutting resistance Ky, the cutting depth ap and the feed rate fz in the Y-axis direction. The external force Fz is also the value obtained by multiplying the specific cutting resistance Kz, the cutting depth ap and the feed rate fz representing the state of the blade in the Z-axis direction. Since each of the specific cutting resistance Kx, the specific cutting resistance Ky and the specific cutting resistance Kz changes according to the state of the tool tip in each axial direction, the values ​​of the specific cutting resistance Kx, the specific cutting resistance Ky and the specific cutting resistance Kz are different from each other.

[0087] <Experimental Example of Tool Wear>

[0088] Below, use Figure 8 to Figure 10 An experimental example of detecting the wear state of the milling tool 50 is shown. Figure 8 to Figure 10 The experimental results under the following machining conditions are shown in FIG. 5 . The material of the workpiece is carbon steel (S50C). The milling tool 50 is a four-edge end mill. The tool diameter is The cutting speed is 60m / min. The feed rate of each cutting edge is 0.015mm / t(tooth). The axial cutting depth is 1mm. The radial cutting depth is 2.4mm.

[0089] Figure 8 is a first example of a graph showing the state of the milling tool 50. Figure 8 In the first example shown in the graph, the vertical axis represents the external force Fz, and the horizontal axis represents the external force Fxy. Figure 8 The plot points N11 to N18 are shown in FIG. Each of the plot points N11 to N18 represents the Figure 2 to Figure 6 The external force Fz and the external force Fxy at a specific timing are calculated by the method described in .

[0090] Plot points N11 to N18 are values ​​detected during the period when the milling tool 50 is rotated by the motor 20 to cut the workpiece, and are detected in the order of plot points N11 to N18. Plot point N11 is the value detected at the earliest time, and plot point N18 is the value detected at the latest time. That is, the number of cutting times and cutting time are the largest when the plot point N18 is detected compared to the times when the other plot points are detected. Therefore, when the plot point N18 is detected, the wear of the milling tool 50 is aggravated compared to the times when the other plot points are detected.

[0091] like Figure 8 As shown in the plotted points N11 to N18, if the number of cuts and the cutting time increase, the wear of the milling tool 50 increases, and the external force Fz and the external force Fxy both show an increasing trend. Figure 7 As shown in the state St2, if the wear increases, the contact area between the workpiece 60 and the milling tool 50 increases. If the contact area increases, the contact time and friction between the milling tool 50 and the workpiece 60 increase, so the external force Fz and the external force Fxy also increase.

[0092] That is, each plotted point moves toward the upper right direction on the graph as the wear increases. The cutting area is determined independently of the state of the blade tip. In addition, since the blade repeatedly contacts the workpiece 60, the size of the cutting area sometimes deviates each time the blade contacts the workpiece 60. Therefore, even when the wear of the blade tip increases, the external force Fz and the external force Fxy sometimes decrease depending on the size of the cutting area. However, if the trend of movement from the plotted point N11 to the plotted point N18 is grasped as a whole, each plotted point moves toward the upper right direction on the graph.

[0093] As a result, users can Figure 8 The degree of wear can be estimated based on the direction and amount of movement of the plotted points in the graph shown. That is, the state detection system can visually display the degree of wear indicating the state of the milling tool 50 to the user. That is, in the state detection system 100 of this embodiment, the user can recognize the state of wear of the milling tool 50 based on the trend of the moving direction and the moving amount of the plotted points. As a result, the user can easily predict the replacement time of the milling tool 50.

[0094] Fig. 9 is a second example of a graph showing the state of the milling tool 50. Fig. 9 In the graph of the second example shown in FIG. 1 , the vertical axis represents the external force Fxy, and the horizontal axis represents the load torque Mz. Fig. 9, plot points N21 to N28 are shown. Plot points N21 to N28 are detected in the order of plot points N21 to N28, similarly to plot points N11 to N18. That is, among plot points N21 to N28, the timing when plot point N28 is detected is the timing when wear is most severe.

[0095] like Fig. 9 As shown in the plotted points N21 to N28, if the number of cuts and the cutting time increase, the wear of the milling tool 50 increases, and the external force Fxy and the load torque Mz both show an increasing trend. Figure 7 As shown in state St2, if the wear increases, the contact area between the workpiece and the milling tool 50 increases. When the contact area increases, the friction force increases, so the load torque acting in the direction that hinders the rotation of the milling tool 50 also increases. Fig. 9 As shown in Figure 2, if the wear increases, the load torque Mz will also increase. Fig. 9 The plotted points in the graph also tend to move toward the upper right on the graph.

[0096] Thus, in the state detection system 100 of the present embodiment, the vertical axis represents the external force Fxy, and the horizontal axis represents the load torque Mz. Fig. 9 In the graph of , the user can also recognize the wear state of the milling tool 50 based on the trend of the moving direction and the moving amount of the plotted points.

[0097] Fig.10 is a third example of a graph showing the state of the milling tool 50. Fig.10 In the graph of the third example shown, the vertical axis represents the external force Fz and the horizontal axis represents the load torque Mz. Fig.10 Plot points N31 to N38 are shown in FIG. Plot points N31 to N38 are detected in the same order as plot points N11 to N18. That is, among plot points N31 to N38, the timing when plot point N38 is detected is the timing when the wear is most severe. Fig.10 In the curve diagram, when the wear increases, the external force Fz and the load torque Mz also increase, so Fig.10 The plotted points in also have a tendency to move toward the upper right on the graph.

[0098] Thus, in the state detection system 100 of the present embodiment, the vertical axis represents the external force Fz, and the horizontal axis represents the load torque Mz. Fig.10 In the graph of , the user can also recognize the wear state of the milling tool 50 based on the trend of the moving direction and the moving amount of the plotted points.

[0099] In addition, in the state detection system 100, when the plotted point is detected in a range other than the predetermined normal area, it is detected that an abnormality has occurred, and the situation is displayed on the display device 40. More specifically, a trial machining is performed under a specific milling tool shape and specific machining conditions, and the normal range is set in advance. Figure 8 to Figure 10 The range of the plotted points detected with wear is obtained in the graph of . That is, in the state detection system 100, the moving range of the plotted points when the wear increases normally is obtained in advance. Thereafter, when the milling tool of the same shape as a new milling tool is used to restart the processing under the same processing conditions, it is determined whether the plotted points detected in the new milling tool exceed the moving range of the plotted points when the wear increases normally obtained in advance. When the plotted points are detected in a range different from the moving range of the plotted points when the wear increases normally, the management device 10 determines that an abnormality has occurred, and causes the display device 40 to display the meaning of the abnormality.

[0100] Figure 8 to Figure 10 The graphs of each of the above graphs represent the relationship between at least two of the external force Fz, the external force Fxy, and the load torque Mz. More specifically, Figure 8 The curve graph shows the relationship between the external force Fz and the external force Fxy. Fig. 9 The curve diagram shows the relationship between the external force Fxy and the load torque Mz. Figure 8 The curve graph shows the relationship between the external force Fz and the load torque Mz. Figure 8 to Figure 10 The information shown in the graph is an example of the “first information” in the present disclosure.

[0101] In the state detection system 100 of this embodiment, it is also possible to not only show Figure 8 to Figure 10 A curve diagram in the curve diagram also shows Figure 8 to Figure 10 That is, the management device 10 can make Figure 8 The curve graph and Fig. 9 The graph of is displayed on the display device 40. In addition, the management device 10 can Fig. 9 The curve graph and Fig.10 The graph of is displayed on the display device 40. Alternatively, the management device 10 can Figure 8 The curve graph and Fig.10 The graph is displayed on the display device 40. Thus, a graph including all the information of the external force Fz, the external force Fxy, and the load torque Mz is displayed on the display device 40, and in the state detection system 100, information representing the state of the milling tool 50 more accurately can be displayed to the user. When two graphs are displayed in this way, one graph is an example of the "first information", and the other graph is an example of the "second information". It should be noted that in the state detection system 100, Figure 8 to Figure 10 All three graphs.

[0102] In the present embodiment, an example of displaying the relationship between the external force Fz, the external force Fxy, and the load torque Mz as a curve graph is described, but for example, the magnitudes of the external force Fz, the external force Fxy, and the load torque Mz may be simply displayed as numerical values ​​in a table form. In addition, in the above example, an example of displaying to the user in the form of a two-dimensional curve graph is described, but in one aspect, the state detection system 100 may also use a three-dimensional curve graph to display the relationship between the external force Fz, the external force Fxy, and the load torque Mz. In such a three-dimensional curve graph, for example, the X-axis represents the external force Fz, the Y-axis represents the external force Fxy, and the Z-axis represents the load torque Mz.

[0103] <Experimental example of blade tip damage>

[0104] Below, use Figure 11 to Figure 13 An experimental example of detecting the state of the cutting edge defect of the milling tool 50 is shown. Figure 11 to Figure 13 The experimental results under the following processing conditions are shown in FIG. 5 . The material of the workpiece is stainless steel (SUS304). The milling tool 50 is a four-edge end mill. The tool diameter is The cutting speed is 80m / min. The feed rate of each cutting edge is 0.10mm / t(tooth). The axial cutting depth is 2mm. The radial cutting depth is 10mm.

[0105] Fig.11 is a fourth example of a graph showing the state of the milling tool 50. Fig.11 In the graph of the fourth example shown, the vertical axis represents the external force Fz and the horizontal axis represents the external force Fxy. Fig.11 The plot point group Ns1 included in the area Ar1 and the plot point group Ns2 included in the area Ar2 are shown. The plot point group Ns1 is a value detected when the blade edge is not chipped. The plot point group Ns2 is a value detected when the blade edge is chipped.

[0106] like Fig.11 As shown in the plotted point groups Ns1 and Ns2, the external force Fxy increases due to the defect in the tool tip. That is, the plotted area moves to the right on the graph based on the fact that the tool tip has a defect. Tool tip defects do not increase over time like tool wear, but are suddenly damaged. Therefore, before and after the tool tip defect occurs, the plotted area moves from area Ar1 to area Ar2.

[0107] Thus, the state detection system 100 of this embodiment can allow the user to recognize whether the cutting edge of the milling tool 50 is damaged based on the fact that the drawn area Ar1 changes to another area Ar2. Thus, the user can determine whether the milling tool 50 needs to be repaired.

[0108] In the example of a defective blade tip, the directions in which each plotted point moves are different depending on the position and shape of the defective blade tip, so there is no trend in the moving directions of each plotted point. Therefore, in the state detection system 100 of the present embodiment, for example, the k-nearest neighbor method is used to determine whether the drawing is in an area different from the area Ar1 drawn when the blade tip is not defective. That is, when the newly drawn value is clustered in a range different from the past plotted points, the management device 10 determines that the blade tip is damaged, and displays this on the display device 40. Thus, in the state detection system 100, the defective state of the blade tip can be detected and the detection result can be displayed to the user. As described later, the management device 10 can also determine whether the blade tip has an abnormality by calculating the tool shape and processing conditions, or by comparing with a normal area obtained by a previously performed test.

[0109] Fig.12 is a fifth example of a graph showing the state of the milling tool 50. Fig.12 In the graph of the fifth example shown, the vertical axis represents the external force Fxy and the horizontal axis represents the load torque Mz. Fig.12 The plot point group Ns3 included in the area Ar3 and the plot point group Ns4 included in the area Ar4 are shown. The plot point group Ns3 is a value detected when the blade tip is not chipped. The plot point group Ns4 is a value detected when the blade tip is chipped.

[0110] like Fig.12 As shown in the plotted point group Ns3 and the plotted point group Ns4, Fig.12 In the example of the defective blade tip, the position and shape of the defective blade tip increase the external force Fxy and decrease the load torque Mz. That is, the plotted area moves to the upper left on the graph based on the fact that the blade tip is defective. Thus, in the state detection system 100 of the present embodiment, the vertical axis represents the external force Fxy and the horizontal axis represents the load torque Mz. Fig.12 In the graph of , the user can recognize whether or not a defect of the cutting edge has occurred in the milling tool 50 based on the fact that the plotted area Ar3 changes to another area Ar4.

[0111] Fig.13 is a sixth example of a graph showing the state of the milling tool 50. Fig.13 In the graph of the sixth example shown, the vertical axis represents the external force Fz and the horizontal axis represents the load torque Mz. Fig.13The plot point group Ns5 included in the area Ar5 and the plot point group Ns6 included in the area Ar6 are shown. The plot point group Ns5 is a value detected in a state where the blade edge is not chipped. The plot point group Ns6 is a value detected in a state where the blade edge is chipped.

[0112] like Fig.13 As shown in the plotted point group Ns5 and the plotted point group Ns6, Fig.12 In the example of the defective tool tip, the load torque Mz is reduced due to the influence of the position and shape of the defective tool tip. That is, each plotted point moves to the left on the graph based on the fact that the tool tip is defective. Thus, in the state detection system 100 of the present embodiment, the vertical axis represents the external force Fz and the horizontal axis represents the load torque Mz. Fig.13 In the graph of , the user can recognize whether or not a defect of the cutting edge has occurred in the milling tool 50 based on the fact that the plotted area Ar5 has changed into another area Ar6.

[0113] <Eliminating the influence of cutting area>

[0114] Fig.14 This is a diagram for explaining the relationship between external force, specific cutting resistance and cutting area. As described above, the blade portion repeatedly contacts the workpiece 60, so the size of the cutting area may vary. Even if the specific cutting resistance K changes due to tool wear or tool tip defect, if the size of the cutting area varies, the external force Fx, external force Fy, external force Fz and load torque Mz may be offset in a manner that the specific cutting resistance K does not change. Therefore, the following describes a method for eliminating the influence of the cutting area.

[0115] exist Fig.14 1 and 2 show the blade 6A in states St4, St5, and St6, respectively. States St4 and St5 are states where the blade 6A has no problems and can perform cutting appropriately. State St6 is a state where the blade edge of the blade 6A is worn.

[0116] In the state St4 and the state St6, the cutting depth ap of the blade 6A is the distance D2. In the state St5, the cutting depth ap of the blade 6A is the distance D3. The distance D3 is longer than the distance D2. In addition, the feed amount fz in all the states St4, St5, and St6 is the same value.

[0117] like Figure 7As described in , the external force Fx is a value obtained by multiplying the specific cutting resistance Kx, which indicates the state of the blade, the cutting depth ap, and the feed rate fz. The specific cutting resistance Kx is determined according to the state of the blade regardless of the cutting depth ap and the feed rate fz. On the other hand, the cutting depth ap and the feed rate fz vary according to the contact condition between the blade and the workpiece 60 regardless of the state of the blade.

[0118] In state St4, the external force Fx is determined based on the specific cutting resistance Kx, which indicates an appropriate state where the blade is neither worn nor defective, the cutting depth apD2 when the cutting depth is a distance D2, and the feed amount fz. In state St5, the external force Fx is determined based on the specific cutting resistance Kx, which indicates an appropriate state where the blade is neither worn nor defective, the cutting depth apD3 when the cutting depth is a distance D3, and the feed amount fz. In state St6, the external force Fx is determined based on the specific cutting resistance Kxf when the blade is worn, the cutting depth apD2 when the cutting depth is a distance D2, and the feed amount fz. Fig.14 As shown, the external force Fy and the external force Fz in each state are determined in the same manner as the external force Fx.

[0119] like Fig.14 As shown in the lower part of state St4, in state St4, the ratio of external force Fx to external force Fz is the ratio of specific cutting resistance Kx to specific cutting resistance Kz. That is, since external force Fz and external force Fx respectively include the cutting depth apD2 and feed amount fz, when external force Fz is divided by external force Fx, the influence of cutting depth apD2 and feed amount fz is eliminated. Therefore, the ratio of external force Fx to external force Fz eliminates the influence of cutting depth apD2 and feed amount fz, and becomes the ratio of specific cutting resistance Kx to specific cutting resistance Kz. In state St4, the ratio of external force Fy to external force Fz also eliminates the influence of cutting depth apD2 and feed amount fz, and becomes the ratio of specific cutting resistance Ky to specific cutting resistance Kz.

[0120] like Fig.14 As shown in the lower part of the state St5, the ratio of the external force Fx to the external force Fz in the state St5 is also the ratio of the specific cutting resistance Kx to the specific cutting resistance Kz in the same manner as in the state St4. That is, the influence of the cutting depth apD3 and the feed amount fz is eliminated by the division operation. Therefore, the ratio of the external force Fx to the external force Fz in the state St5 is the same as the ratio of the external force Fy to the external force Fz in the state St4.

[0121] On the other hand, Fig.14As shown in the lower part of state St6, in state St6, the ratio of external force Fx to external force Fz is the ratio of specific cutting resistance Kxf to specific cutting resistance Kzf. The influence of cutting depth apD2 and feed amount fz is eliminated by division operation, but due to the wear of the blade, specific cutting resistance Kxf and specific cutting resistance Kzf are different from specific cutting resistance Kx and specific cutting resistance Kz in state St4 and state St5. Therefore, it is a value different from the ratio of external force Fx to external force Fz in state St6 and the ratio of external force Fy to external force Fz in state St4 and state St5.

[0122] In this way, in the state detection system 100 of the present embodiment, by using the values ​​obtained by dividing the external force Fx, the external force Fy, and the external force Fz, the influence of the cutting area can be eliminated, and the change of only the specific cutting resistance K can be focused. For example, the management device 10 can display the state of the milling tool 50 excluding the influence of the cutting area to the user by displaying a graph in which the vertical axis represents the ratio of the external force Fx to the external force Fz and the horizontal axis represents the ratio of the external force Fy to the external force Fz. It should be noted that as long as the influence of the cutting area can be eliminated, the combination of dividing the external force Fx, the external force Fy, and the external force Fz may be other combinations.

[0123] <Exclusion of cutting area using load torque>

[0124] Fig.15 The load torque Mz is a force that hinders rotation and is a value obtained by multiplying the external force Ft generated in the tangential direction of the milling tool 50 by the radius R1 of the milling tool 50. Figure 6 In the description, the arrow extending from the tangent direction of the blade 6A is described as the load torque MzA, but in reality, Fig.15 As shown, it is a value obtained by multiplying the external force Ft, which is the component force in the tangential direction of the external force FxyA, by the radius R1 of the milling tool 50 .

[0125] The external force Ft is the value obtained by multiplying the specific cutting resistance Kt, the cutting depth ap and the feed rate fz, similarly to the external force Fx, the external force Fy and the external force Fz. That is, the load torque Mz includes the cutting depth ap and the feed rate fz. Therefore, by dividing any one of the external force Fx, the external force Fy and the external force Fz by the load torque Mz, the influence of the cutting area can be eliminated.

[0126] Fig.16 is a seventh example of a graph showing the state of the milling tool 50. Fig.16 In the graph of the seventh example shown, the vertical axis represents the ratio of the external force Fz to the load torque Mz, and the horizontal axis represents the ratio of the external force Fxy to the load torque Mz. Fig.16, plot points N41 to N48 are shown. Plot points N41 to N48 are detected in the same order as plot points N11 to N18. That is, among plot points N41 to N48, the timing when plot point N48 is detected is the timing when wear is most severe.

[0127] exist Fig.16 In the graph shown, as described above, the influence of the cutting area is excluded from the values ​​shown on the vertical axis and the horizontal axis. Fig.16 The curve graph can show the change of the cutting resistance K more accurately.

[0128] exist Fig.16 In the example shown, if wear increases, the ratio of the external force Fxy to the load torque Mz decreases. That is, the rate of increase of the load torque Mz caused by increased wear is greater than the rate of increase of the external force Fxy. In addition, if wear increases, the ratio of the external force Fxy to the load torque Mz increases. The rate of increase of the load torque Mz caused by increased wear is less than the rate of increase of the external force Fxy. Therefore, Fig.16 As shown, each plotted point has a tendency to move toward the lower right direction on the graph.

[0129] Fig.17 is an eighth example of a graph showing the state of the milling tool 50. Fig.17 In the graph of the eighth example shown, the vertical axis represents the ratio of the external force Fz to the load torque Mz, and the horizontal axis represents the ratio of the external force Fxy to the load torque Mz. Fig.17 The plot point group Ns7 included in the area Ar7 and the plot point group Ns8 included in the area Ar8 are shown. The plot point group Ns7 is a value detected in a state where the blade tip is not chipped. The plot point group Ns8 is a value detected in a state where the blade tip is chipped.

[0130] like Fig.17 As shown in the plotted point groups Ns7 and Ns8, the ratio of the external force Fxy to the load torque Mz increases due to the occurrence of the tool tip defect. That is, the plotted area moves to the right on the graph based on the fact that the tool tip has a defect. Thus, in the state detection system 100 of this embodiment, the vertical axis represents the ratio of the external force Fz to the load torque Mz, and the horizontal axis represents the ratio of the external force Fxy to the load torque Mz. Fig.17 In the graph of , the user can recognize whether or not a defect of the cutting edge has occurred in the milling tool 50 based on the fact that the plotted area Ar7 has changed into another area Ar8.

[0131] In this way, Fig.16 , Fig.17In the state detection system 100 of the present embodiment, the vertical axis represents the external force Fz relative to the load torque Mz, and the horizontal axis represents the external force Fxy relative to the load torque Mz. Fig.16 , Fig.17 The graph of can also enable the user to recognize the wear state of the milling tool 50 and the defect of the cutting edge.

[0132] In addition, if Figure 6 As described in , as long as the blade of the rotating milling tool 50 is in contact with the workpiece 60, the load torque Mz is always greater than "0". On the other hand, for each of the external forces Fx, Fy, and Fz, the external forces generated by each blade sometimes cancel each other out and appear to be "0". Fig.16 , Fig.17 In the example shown, the denominator of the values ​​shown on the vertical axis and the horizontal axis is the load torque. Therefore, the values ​​shown on the vertical axis and the horizontal axis are not divided by "0", so there is no situation where the value shown on the vertical axis and the horizontal axis cannot be detected due to the value being divided by "0".

[0133] It should be noted that the strain sensors N1 to N3 and the strain sensor S4 are examples of each of “first to fourth strain sensors” in the present disclosure.

[0134] Fig.18 is a flowchart showing the processing steps of this embodiment. Fig.18 In the figure, it is shown that the Figure 8 to Figure 13 , Fig.16 , Fig.17 The processing steps of any curve graph in . Fig.18 The processing steps shown are realized by the CPU 220 of the management device 10 executing the program in the storage device 230 .

[0135] The management device 10 obtains the external force Fz (step S100). Next, the management device 10 obtains the external force Fxy (step S110). Furthermore, the management device 10 obtains the load torque Mz (step S120). More specifically, in steps S100 to S120, the management device 10 Figure 3 , Figure 4 As described in , the external force Fz, the external force Fxy, and the load torque Mz are calculated using the detection values ​​of the strain sensors N1 to N3 and the strain sensor S4.

[0136] After that, the management device 10 displays a graph created based on at least two of the external force Fz, the external force Fxy, and the load torque Mz (step S130). Figure 8 to Figure 13 , Fig.16 , Fig.17 Any curve graph in .

[0137] [Method for creating a normal area based on a test performed in advance]

[0138] In the state detection system 100 of this embodiment, the configuration of using the k-nearest neighbor method to determine whether a different area is drawn from the area Ar1 drawn in the state where the blade tip is not damaged is described. However, the method of determining whether an abnormality has occurred is not limited to the method using the k-nearest neighbor method. The following describes a method of creating a normal area on a graph.

[0139] Fig.19 : is a graph showing the measurement results of the test for making a normal area. Fig.19 The time series data of the external force Fz, the external force Fxy and the load torque Mz are shown in FIG. Fig.19 2 shows the values ​​of the external force Fz, the external force Fxy, and the load torque Mz in the period from 0 to 17.5 seconds.

[0140] exist Fig.19 , the measurement results of the test performed under the following machining conditions are shown. The rotation speed of the milling tool 50 is 2300 times / min. The feed rate is 500mm / min. The radial penetration amount is 10mm. That is, the blades 6A to 6C cut the workpiece in a manner in which the penetration amount is gradually increased from 0mm to 10mm.

[0141] like Fig.19 As shown, the external force Fz, the external force Fxy and the load torque Mz change with the passage of time. The period Dr1 is a period when the cutting amount is 0 mm to 1 mm. The period Dr2 is a period when the cutting amount is 4 mm to 5 mm. The period Dr3 is a period when the cutting amount is 9 mm to 10 mm.

[0142] Fig. 20 is based on Fig.19 The figure is a graph showing the measurement results of Fig. 20 Four graphs are shown, including a graph with the vertical axis being the external force Fz and the horizontal axis being the load torque Mz, a graph with the vertical axis being the external force Fxy and the horizontal axis being the load torque Mz, a graph with the vertical axis being the external force Fz and the horizontal axis being the external force Fxy, and a graph with the vertical axis being the ratio of the external force Fz to the load torque Mz and the horizontal axis being the ratio of the external force Fxy to the load torque Mz.

[0143] In each graph, three plot points are shown: plot point P1, plot point P2, and plot point P3. Fig. 20 As shown in the upper left part of Fig.19 The plotted point P2 is Fig.19The plotted point P3 is Fig.19 The plotted points in Dr3 during the period. That is, Fig. 20 middle, Fig.19 The values ​​of the external force Fz, the external force Fxy, and the load torque Mz are shown as a graph for each period.

[0144] exist Fig. 20 In the example, instead of Fig.19 The measured values ​​of the external force Fz, external force Fxy, and load torque Mz are shown as plotted points. Fig.19 The moving average of the external force Fz, external force Fxy, and load torque Mz shown is displayed as a plotted point. Fig. 20 As shown in FIG. 1 , each plotted point is fixedly arranged within a predetermined range on the curve graph during the same period. Fig.19 In the experiment, the experiment was conducted under the machining condition in which the cutting depth gradually increased. Therefore, it can be said that the experiment was conducted under different machining conditions in the period Dr1, the period Dr2, and the period Dr3.

[0145] Fig.21 2 is a diagram showing an example of setting the normal area in the period Dr2. Fig.21 It shows that Fig. 20 The four graphs shown are the same graph. Fig.21 The normal area Cr1, the normal area Cr2, the normal area Cr3, and the normal area Cr4 overlapping with the four curve graphs are respectively shown. The normal area Cr1 to the normal area Cr4 are determined based on the plotted point P2 in the period Dr2. The normal area Cr1 to the normal area Cr4 are, for example, areas including all the plotted points P2 in the period Dr2, and are areas represented by ellipses or circles centered on the average value of the set of plotted points P2. The normal area Cr1 to the normal area Cr4 are determined by the management device 10. It should be noted that the management device 10 may also determine the minimum area of ​​the set including all the plotted points P2 as the normal area Cr1 to the normal area Cr4 instead of using the average value of the set of plotted points P2.

[0146] In this way, the state detection system 100 obtains Fig.19 , Fig. 20The area to be drawn for the experimental processing performed in the process is the normal area Cr1 to the normal area Cr4. Afterwards, when processing is performed under the processing conditions corresponding to the period Dr2, if the newly detected plotted points are not located in the normal area Cr1 to the normal area Cr4, it can be determined that an abnormality has occurred. That is, when the management device 10 detects a plotted point in an area that is not in the normal area Cr1 to the normal area Cr4, it can cause the display device 40 to display the meaning of the abnormality. In addition, the management device 10 can also cause the display device 40 to display in real time Fig. 22 The four graphs shown in FIG. 1 and the normal region Cr1 to the normal region Cr4 are shown in FIG. 1 . Thus, the user can visually understand in real time whether each plotted point is within the range of the normal region Cr1 to the normal region Cr4.

[0147] Fig. 22 FIG. 2 is a diagram showing an example of setting the normal area in the period Dr2 and the period Dr3. Fig. 22 , normal area Cr5, normal area Cr6, normal area Cr7, and normal area Cr8 are shown. Normal area Cr5 to normal area Cr8 are determined based on the plot point P2 in period Dr2 and the plot point P3 in period Dr3. Normal area Cr5 to normal area Cr8 are, for example, areas including all plot points P2 and P3, and are rectangular areas centered on the average value of the set of plot points P2 and P3.

[0148] Thus, the state detection system 100 is implemented by Fig.19 , Fig. 20 The normal area Cr5 to the normal area Cr8 is obtained by performing the experimental processing in the period. After that, when processing is performed under the processing conditions corresponding to the period Dr2 and the period Dr3, it can be determined whether an abnormality has occurred based on whether the newly detected plotted points are located in the normal area Cr5 to the normal area Cr8. Fig.21 , Fig. 22 As shown, in the state detection system 100, a normal area corresponding to each processing condition can be created.

[0149] It should be noted that in Fig. 20 In the example, if you do not use Fig.19Although an example of using a moving average value instead of the actual measured value in the state detection system 100 is described, in a certain aspect, the actual measured value may be used, and the average value, maximum value, standard deviation, etc. per unit time may be used. The unit time may be determined based on the rotation speed of the milling tool 50. In addition, in the present embodiment, the state detection of the milling tool using the external force Fx, the external force Fy, and the external force Fxy is described, but in a certain aspect of the state detection system 100, the torque Mx, the torque My, and the torque Mxy generated in each axial direction may be used to replace the external force Fx, the external force Fy, and the external force Fxy, respectively.

[0150] (Variation Example)

[0151] In the milling tool 50 of the present embodiment, the tool holder 30 is used to hold the shaft portion 106. However, in the milling tool 50 of the modified example, the shaft portion 106 may be directly mounted on the spindle of the machine tool 70 without using the tool holder like the milling tool 50 of the present embodiment. In this case, the shaft portion 106 has a housing.

[0152] The strain sensors N1 to N3 and the strain sensor S4 are accommodated in the housing provided in the shaft portion 106. The strain sensors N1 to N3 and the strain sensor S4 are arranged at equal intervals in the circumferential direction of the shaft portion 106, similarly to the milling tool 50 of the present embodiment. In this way, in the milling tool 50 directly mounted on the spindle without using a tool holder, by arranging the strain sensors N1 to N3 and the strain sensor S4 in the housing of the shaft portion 106, the management device 10 can also obtain the external force and load torque generated in the milling tool 50.

[0153] In addition, in the present embodiment, the configuration in which the management device 10 and the machine tool 70 are separate bodies has been described. However, the management device 10 may be included in the machine tool 70. In other words, the management device 10 and the machine tool 70 may be integrally configured.

[0154] The embodiments disclosed this time should be considered in all respects as illustrative rather than restrictive. The scope of the present disclosure is indicated by the claims rather than the above-mentioned embodiments, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0155] Description of Reference Numerals

[0156] 6A-6C: blade; 10: management device; 20: motor; 30: tool holder; 40: display device; 50: milling tool; 60: workpiece; 70: machine tool; 100: state detection system; Ag1-Ag3: configuration; Ar1-Ar8: area; Cx: compression stress; D1-D3: distance; Dv1-Dv3: detection value; Ft, Fx, Fxy, FxyA-FxyC, Fy, Fz: external force; K, Kt, Kx, Kxf, Ky, Kz, Kzf: specific cutting resistance; Mz, MzA~MzC: load torque; N1~N3, S4: strain sensor; N11~N18, N21~N28, N31~N38, N41~N48, P1~P3: plotted points; Ns1~Ns8: plotted point group; R1: radius; Rd: rotation direction; St1~St6: state; Tx, Ty, Tz: stress; ap, apD2, apD3: cutting depth; Cr1~Cr8: normal area.

Claims

1. A state detection system, which is a state detection system for a milling tool used in milling processing, wherein: The state detection system has: A milling tool comprising a shaft portion having a first end portion provided with a blade portion for cutting a workpiece and a second end portion mounted on a machine tool, wherein the milling tool is rotatable around a rotation axis of the shaft portion; A plurality of sensors are mounted on the shaft portion to detect external forces acting on the milling tool; Display device; as well as Management device, The plurality of sensors detect a first force acting on the milling tool in a first direction along the rotation axis, a second force acting on the milling tool in a direction along a plane with the rotation axis as a normal, and a load torque acting on the milling tool in a direction that hinders the rotation of the milling tool. The management device causes the display device to display first information based on at least two of the first force, the second force, and the load torque.

2. The state detection system according to claim 1, wherein: The management device displays the first information using a graph.

3. The state detection system according to claim 1 or 2, wherein: The management device displays the first information on the display device, and further displays second information based on at least two of the first force, the second force, and the load torque on the display device. The second information is information different from the first information.

4. The state detection system according to claim 1, wherein: The first information is information based on a ratio of the first force to the load torque and a ratio of the second force to the load torque.

5. The state detection system according to any one of claims 1 to 4, wherein: The plurality of sensors include: A first strain sensor, a second strain sensor and a third strain sensor are used to detect the strain in the first direction and are installed on the shaft; as well as The fourth strain sensor detects strain of the shaft portion in the circumferential direction and is mounted on the shaft portion.

6. A method for detecting the state of a milling tool used for milling processing, wherein: The milling tool includes a shaft portion having a first end portion provided with a blade portion for cutting a workpiece and a second end portion mounted on a machine tool, and the milling tool is rotatable around a rotation axis of the shaft portion. A plurality of sensors for detecting external forces acting on the milling tool are mounted on the shaft. The method comprises the following steps: using detection values ​​of the plurality of sensors to acquire a first force acting in a first direction along the rotation axis; using the detection values ​​of the plurality of sensors to acquire a second force acting in a direction along a plane having the rotation axis as a normal line; using the detection values ​​of the plurality of sensors to obtain a load torque acting in a direction that hinders the rotation of the milling tool; as well as First information based on at least two of the first force, the second force, and the load torque is displayed.

7. A program for detecting the state of a milling tool used for milling processing, wherein: The milling tool includes a shaft portion having a first end portion provided with a blade portion for cutting a workpiece and a second end portion mounted on a machine tool, and the milling tool is rotatable around a rotation axis of the shaft portion. A plurality of sensors for detecting external forces acting on the milling tool are mounted on the shaft. The program causes the computer to execute the following steps: using detection values ​​of the plurality of sensors to acquire a first force acting in a first direction along the rotation axis; Acquire a second force acting in a direction along a plane with the rotation axis as a normal; acquiring a load torque acting in a direction that hinders the rotation of the milling tool; as well as First information based on at least two of the first force, the second force, and the load torque is displayed.

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