JP2021065997A - Measuring method - Google Patents

Abstract

To provide a measuring method capable of restraining measurement abnormality caused by inclination of a probe.SOLUTION: A central position of a processing hole is calculated by sequentially bringing a probe into contact with a plurality of first measuring object points defined at equal intervals on a circumference of a first cross section in a radial direction of the processing hole of a workpiece. It is determined whether or not a criterion on the number of times of processing on the workpiece or a lapsed time from the last processing is satisfied or not. When the determination criterion is satisfied, a plurality of second measuring object points corresponding to the first measuring object points in at least one second cross section other than a first cross section parallel to the first cross section are measured with the probe. Respective measurement errors for the first measuring object points and the second measuring object points are calculated for each corresponding measuring object point. When at least one of measured errors is equal to or greater than a first threshold value capable of determining measurement abnormality, a measurement abnormal signal is output. When the determination criterion is not satisfied, a position difference between a central position and the central position of the last time corresponding to the central position is calculated, and if the position difference is equal to or greater than a second threshold value larger than the first threshold value, a measurement abnormal signal is output.SELECTED DRAWING: Figure 6

Description

The present invention relates to a measuring method.

It is known to process workpieces using a machining center. It is also known to use a touch probe to measure the center position of the work (see Patent Document 1 above).

Japanese Unexamined Patent Publication No. 2008-076309

By the way, the machining center is equipped with an ATC (Automatic Tool Changer) for automatically changing the tool attached to its own spindle. In particular, the ATC is provided with a substantially disk-shaped tool magazine that holds the above-mentioned touch probe, drill, milling cutter, etc. as a tool on the outer circumference. The tool magazine rotates about the center in the radial direction as a rotation axis, and for example, the drill attached to the spindle is replaced with a touch probe or the like.

Here, when the machining center processes a plurality of workpieces (hereinafter referred to as geographic features) in order with various tools, the tool magazine repeats rotation every time replacement occurs in the process. Since the tool magazine holds the touch probe on its outer circumference, centrifugal force is applied to the touch probe every time the tool magazine rotates. In the touch probe, one end of the stylus extending linearly downward is supported by the probe head, and when centrifugal force is applied to the stylus, the other end of the stylus swings away from the rotation axis of the tool magazine. Be done. As a result, the stylus is tilted from below vertically until the stylus is adjusted to return vertically downward.

Therefore, when measuring the position of the point to be measured by bringing the other end of the stylus into contact with the point to be measured on the inner peripheral surface of the machined hole provided by machining the workpiece, it is normal if the stylus is not tilted. Although the position of the point to be measured can be measured, if the stylus is tilted, it may lead to measurement abnormality.

Therefore, an object of the present invention is to suppress measurement abnormality.

The measuring method according to the present invention applies to a plurality of first measurement points defined at equal intervals on the circumference of the first radial cross section in a cylindrical machined hole provided by processing a workpiece. The step of calculating the center position of the machined hole by bringing the stylus into contact with each other in order, and the step of judging whether or not the judgment criteria regarding the number of times of machining or the elapsed time from the previous machining with respect to the workpiece are satisfied, and the above-mentioned determination. When the criterion is satisfied, the stylus sets a plurality of second measured points corresponding to the first measured points in at least one second cross section other than the first cross section parallel to the first cross section. And the measurement difference between the first measurement point and the second measurement point is calculated for each corresponding measurement point, and at least one of the measurement differences can determine the measurement abnormality. If it is equal to or greater than the first threshold value, the position difference between the step of outputting the measurement abnormality signal and the previous center position corresponding to the center position is calculated when the determination criterion is not satisfied. When the position difference is equal to or greater than the second threshold value larger than the first threshold value, the step of outputting the measurement abnormality signal is included.

According to the present invention, since the measurement abnormality signal is output in the above two steps, the measurement abnormality can be suppressed.

FIG. 1 is a front view of the machining center. FIG. 2 is a front view of the ATC with the cover removed. FIG. 3A is a diagram for explaining a movement example of the touch probe. FIG. 3B is a diagram for explaining a measurement example of the touch probe in a normal state. FIG. 3C is a diagram for explaining a measurement example when the touch probe is abnormal. FIG. 4A is an example of the hardware configuration of the control device. FIG. 4B is an example of the functional configuration of the control device. FIG. 5 is a flowchart (No. 1) relating to the process of realizing the measurement method. FIG. 6 is a flowchart (No. 2) relating to the process of realizing the measurement method. FIG. 7 is a diagram for explaining a measurement method.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

FIG. 1 is a front view of the machining center 30. FIG. 2 is a front view of the ATC 8 with the cover 14 removed. The machining center 30 is a machine tool for processing a workpiece WK. The machining center 30 cuts the surface of the work WK, for example, to form a cylindrical hole (hereinafter referred to as a machined hole) HL in the work WK.

As shown in FIG. 1, the machining center 30 includes a spindle 5. A touch probe 3 or a drill fixed to the tool holder 4 is attached to the spindle 5 as a tool. Further, the machining center 30 includes a chuck member 6 for fixing the workpiece WK and a table 7 on which the chuck member 6 is placed. Further, the machining center 30 includes an ATC 8. The ATC 8 automatically replaces the tool attached to the spindle 5. That is, the touch probe 3 attached to the spindle 5 is replaced for each tool holder 4.

The spindle 5 includes a chuck mechanism for holding and releasing the tool holder 4. Further, the spindle 5 is connected to the rotation drive mechanism. Therefore, the spindle 5 can rotate when the workpiece WK is machined or when the machined hole HL is measured. Further, the spindle 5 includes a left-right movement mechanism for moving the spindle 5 in the positive and negative directions of the X-axis shown in FIG. 1, a vertical movement mechanism for moving the spindle 5 in the positive and negative directions of the Z-axis, and a vertical movement mechanism described later. It is connected to a front-back movement mechanism that moves the spindle 5 in the positive and negative directions of the Y-axis. Therefore, the spindle 5 can move in the positive and negative directions of the X-axis, the Y-axis, and the Z-axis, respectively, when machining the workpiece WK or measuring the drilled hole HL.

As shown in FIG. 1, the upper portion of the ATC 8 is covered with a cover 14, and when the cover 14 is removed from the ATC 8, the ATC 8 includes a tool magazine 11 for holding a plurality of tool holders 4, as shown in FIG. ing. In FIG. 2, a drill 2, a touch probe 3, and the like are fixed to the tool holder 4 as tools. The tool magazine 11 is connected to the rotation drive mechanism 12. The rotation drive mechanism 12 includes a drive motor for rotating the tool magazine 11 around a rotation axis R1 parallel to the Z-axis direction, a power transmission mechanism for transmitting the power of the drive motor to the tool magazine 11, and the like. ing. Therefore, the tool magazine 11 can rotate about the rotation axis R1.

The tool magazine 11 is also connected to the moving mechanism 13. The moving mechanism 13 is a power transmission mechanism for transmitting the power of the drive source 15 including a drive motor, an air cylinder, etc. for moving the tool magazine 11 in the positive and negative directions of the X-axis to the tool magazine 11. , A guide mechanism for guiding the tool magazine 11 in the positive and negative directions of the X-axis is provided. As a result, the tool magazine 11 can move in the positive and negative directions of the X-axis shown in FIG. 2 together with the rotation drive mechanism 12.

FIG. 3A is a diagram for explaining a movement example of the touch probe 3. FIG. 3B is a diagram for explaining a measurement example of the touch probe 3 in a normal state. FIG. 3C is a diagram for explaining a measurement example when the touch probe 3 is abnormal.

As shown in FIG. 3A, the touch probe 3 can move in the X-axis direction, the Y-axis direction, or the like with a part of itself inserted in the machined hole HL provided in the workpiece WK. Specifically, first, the probe head (for example, a housing) 3a of the touch probe 3 is positioned at the theoretical value center O obtained by design, experiment, or the like, and moves in the positive direction of the X axis. Here, as shown in FIG. 3B, the touch probe 3 includes a stylus 3b that extends linearly downward from the probe head 3a. One end of the stylus 3b is supported by the probe head 3a, and the other end of the stylus 3b is branched into two. One of the other ends of the stylus 3b extends at a right angle from the vertical direction, and has a first contact c1 at its tip that contacts the inner peripheral surface of the machined hole HL. The other end of the stylus 3b is provided with a second contact c2 that contacts the bottom surface of the machined hole HL at the tip in the vertical direction.

Therefore, when the stylus 3b moves from the theoretical value center O in the positive direction of the X-axis, as shown in FIGS. 3A and 3B, the first contact c1 of the stylus 3b becomes the inner peripheral surface of the machined hole HL. Contact a predetermined part of. As a result, the touch probe 3 (specifically, the stylus 3b) measures the three-dimensional position of the portion in contact with the first contact c1 as the measurement point.

After the measurement, the probe head 3a of the touch probe 3 returns to the theoretical value center O, rotates 180 degrees around the theoretical value center O, and moves in the negative direction of the X axis. As a result, as shown in FIGS. 3A and 3B, the first contact c1 of the stylus 3b comes into contact with another portion of the inner peripheral surface of the machined hole HL. As a result, the touch probe 3 measures the three-dimensional position of another portion in contact with the first contact c1 as a measurement point. After that, similarly, the probe head 3a of the touch probe 3 returns to the theoretical value center O, and as shown in FIG. 3A, rotates −90 degrees around the theoretical value center O as the central axis and moves in the positive direction of the Y axis. And measure. After the measurement, the probe head 3a of the touch probe 3 returns to the theoretical value center O, rotates 180 degrees about the theoretical value center O as the central axis, and moves in the negative direction of the Y axis for measurement. As a result, four measurement points are measured.

Here, since the tool magazine 11 holds the touch probe 3 and the like on its outer circumference (see FIG. 2), centrifugal force is applied to the touch probe 3 each time the tool magazine 11 rotates. Since one end of the stylus 3b of the touch probe 3 is supported by the probe head 3a, when a centrifugal force is applied to the stylus 3b, the other end of the stylus 3b is in the direction away from the rotation axis R1 of the tool magazine 11. to be dumped. As a result, as shown in FIG. 3C, the stylus 3b is tilted from the rotation axis R2 of the spindle 5 until the stylus 3b is adjusted to return vertically downward.

As a result, as shown in FIG. 3C, the first contact c1 of the stylus 3b has the predetermined predetermined contact c1 as described above, as compared with the case where the stylus 3b is parallel to the rotation axis R2 as shown in FIG. 3B. Contact a part different from the part of. Therefore, the touch probe 3 measures the three-dimensional position of the portion slightly above the predetermined portion described above as the measurement point. In this way, when the machining center 30 processes a plurality of workpieces WK in order with various tools, the measurement points can be measured in a normal range from the first to several hundreds, but after that, the measured points can be measured. , The stylus 3b can be tilted to obtain an abnormal measurement outside the normal range. Hereinafter, a method capable of suppressing a measurement abnormality even when the stylus 3b is tilted will be described.

First, the control device 40 that controls the machining center 30 will be described with reference to FIGS. 4A and 4B.

FIG. 4A is an example of the hardware configuration of the control device 40. FIG. 4B is an example of the functional configuration of the control device 40. The control device 40 may be a CNC (Computer Numerical Control) device, a PC (Personal Computer), or a tablet terminal.

The control device 40 includes a CPU (Central Processing Unit) 40A, a RAM (Random Access Memory) 40B, and a ROM (Read Only Memory) 40C. Further, the control device 40 includes a display 40D, a communication interface (denoted as I / F in FIG. 4A) 40E, and a touch panel 40F. The CPU 40A, RAM 40B, ROM 40C, display 40D, communication interface 40E, and touch panel 40F are connected to each other by an internal bus 40G. An auxiliary storage device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) may be connected to the internal bus 40G.

The communication interface 40E is provided with a connection terminal such as a USB (Universal Serial Bus) port, and is connected to the spindle 5 or ATC 8 of the machining center 30 by the communication cable 50. In the RAM 40B described above, the program stored in the ROM 40C is temporarily stored by the CPU 40A. When the CPU 40A executes the stored program, the CPU 40A realizes various functions and also executes various processes. The program may be adapted to the flowchart described later. Further, instead of the ROM 40C, the CPU 40A may realize various functions and execute various processes by executing the program stored in the auxiliary storage device described above by the CPU 40A.

FIG. 4B shows a main part of the function of the control device 40. As shown in FIG. 4B, the control device 40 includes a storage unit 41, a control unit 42, a communication unit 43, an input unit 44, and a display unit 45. The storage unit 41 can be realized by at least one of a RAM 40B, a ROM 40C, and an auxiliary storage device. The control unit 42 can be realized by the CPU 40A. The communication unit 43 can be realized by the communication interface 40E. The input unit 44 can be realized by the touch panel 40F. The display unit 45 can be realized by the display 40D. Therefore, the storage unit 41, the control unit 42, the communication unit 43, the input unit 44, and the display unit 45 are connected to each other. In this way, the control device 40 and the machining center 30 are connected via the communication unit 43.

Next, the measurement method according to the present embodiment will be described with reference to FIGS. 5 to 7.

FIG. 5 is a flowchart (No. 1) relating to the process of realizing the measurement method. FIG. 6 is a flowchart (No. 2) relating to the process of realizing the measurement method. FIG. 7 is a diagram for explaining a measurement method. The flowchart shown in FIG. 5 and the flowchart shown in FIG. 6 are continuous. When the control unit 42 controls the operation of the spindle 5, the stylus 3b moves to various positions to perform measurement.

First, as shown in FIGS. 5 and 7, the control unit 42 moves the stylus 3b on the XY cross section on the central axis Oz of the machined hole HL (step S1). As a result, the stylus 3b (more specifically, the second contact c2 of the stylus 3b) is positioned on the central axis Oz. The central axis Oz is parallel to the Z axis and passes through the theoretical value center O.

Next, the control unit 42 moves the stylus 3b to the theoretical value center O of the machined hole HL on the Z axis (step S2). As a result, the stylus 3b (more specifically, the second contact c2 of the stylus 3b) descends along the central axis Oz, and the first contact c1 of the stylus 3b is located in the XY cross section including the theoretical value center O. Stop at. More specifically, since the height of the first contact c1 in contact with the inner peripheral surface of the machined hole HL and the height of the second contact c2 in contact with the bottom surface of the machined hole HL are different (see FIG. 3B), the control unit 42 For example, the stylus 3b is moved to a position where the first contact c1 can measure the first measurement point P1. In other words, the branch point between the first contact c1 and the second contact c2 at the other end of the stylus 3b is positioned at the theoretical value center O.

Next, the control unit 42 causes the stylus 3b to measure the first measurement point P1 on the X-axis (step S3). More specifically, the control unit 42 measures the first measured point P1 by rotating the spindle 5 in the direction in which the first contact c1 faces the first measured point P1 and moving the stylus 3b in the positive direction of the X axis. Let me. When the first contact c1 contacts the first measurement point P1 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the first measurement point P1.

Next, the control unit 42 causes the stylus 3b to measure the second measurement point P2 on the X-axis (step S4). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, rotates the spindle 5 in the direction in which the first contact c1 faces the second measurement point P2, and moves the stylus 3b in the negative X-axis direction. Then, the second measurement point P2 is measured. When the first contact c1 contacts the second measurement point P2 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the second measurement point P2.

Next, the control unit 42 calculates the measured value center on the X-axis on the stylus 3b (step S5). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, and actually measures it on the X-axis based on the three-dimensional position of the first measured point P1 and the three-dimensional position of the second measured point P2. Calculate the value center. Even if the stylus 3b is tilted with respect to the rotation axis R1 of the spindle 5, the X coordinate of the center of the measured value calculated by the control unit 42 and the X coordinate of the center of the theoretical value match.

Next, the control unit 42 causes the stylus 3b to measure the third measurement point P3 on the Y axis (step S6). More specifically, the control unit 42 measures the third measured point P3 by rotating the spindle 5 in the direction in which the first contact c1 faces the third measured point P3 and moving the stylus 3b in the positive direction of the Y axis. Let me. When the first contact c1 contacts the third measurement point P3 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the third measurement point P3.

Next, the control unit 42 causes the stylus 3b to measure the fourth measurement point P4 on the Y axis (step S7). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, rotates the spindle 5 in the direction in which the first contact c1 faces the fourth measurement point P4, and moves the stylus 3b in the negative direction on the Y axis. Then, the fourth measurement point P4 is measured. When the first contact c1 contacts the fourth measured point P4 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the fourth measured point P4.

Next, the control unit 42 calculates the measured value center on the Y-axis on the stylus 3b (step S8). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, and actually measures it on the Y-axis based on the three-dimensional position of the third measured point P3 and the three-dimensional position of the fourth measured point P4. Calculate the value center. Even if the stylus 3b is tilted with respect to the rotation axis R2 of the spindle 5, the Y coordinate of the center of the measured value calculated by the control unit 42 and the Y coordinate of the center of the theoretical value match.

In this way, the first measured point P1, the second measured point P2, the third measured point P3, and the fourth measured point defined at equal intervals on the circumference of the radial cross section of the machined hole HL. By bringing the stylus 3b into contact with P4 in order, the control unit 42 calculates the X coordinate and the Y coordinate of the measured value center of the machined hole HL.

By the way, when the three-dimensional position of the first measured point P1 or the like described above is measured, there is a possibility that the three-dimensional position of the first measured point P1 or the like cannot be measured accurately due to a foreign object being caught during the measurement. is there. Specifically, there is a foreign substance such as chips between the first contact c1 and the first measured point P1, and the stylus 3b is three-dimensionally located at the first measured point P1 in a state where the foreign substance is caught. There is also the possibility of measuring the position. In this case, if the second and subsequent workpieces WK are to be machined based on the measured value center calculated by the control unit 42, the measured value center deviates from the theoretical value center O, so that the geographic WK cannot be machined accurately. Highly sex.

Therefore, after the processing in step S8 is completed, the control unit 42 determines whether or not the predetermined determination criteria regarding the number of times of processing or the elapsed time from processing is satisfied (step S9). For example, if it is the first time since the power of the machining center 30 is turned on, or if several minutes or more than ten minutes have passed since the previous machining, the control unit 42 determines that the predetermined determination criteria are satisfied ( Step S9: YES). In this case, the control unit 42 measures several measurement points on the circumference where at least one other XY cross section different from the XY cross section including the theoretical value center O and the cross section of the machined hole HL intersect with the stylus 3b. Let me.

Specifically, as shown in FIGS. 5 and 7, the control unit 42 raises the stylus 3b by 3 mm in the Z-axis direction from the theoretical value center O of the machined hole HL (step S10). As a result, the first contact c1 of the stylus 3b is positioned at a position where it can come into contact with the fifth measured point P5 to the eighth measured point P8. In the present embodiment, 3 mm is described as an ascending amount of the stylus 3b as an example, but the ascending amount may be appropriately changed based on a design or the like.

Next, the control unit 42 causes the stylus 3b to measure the fifth measurement point P5 on the X-axis (step S11). More specifically, the control unit 42 measures the fifth measured point P5 by rotating the spindle 5 in the direction in which the first contact c1 faces the fifth measured point P5 and moving the stylus 3b in the positive direction of the X axis. Let me. When the first contact c1 contacts the fifth measured point P5 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the fifth measured point P5.

Next, the control unit 42 causes the stylus 3b to measure the sixth measurement point P6 on the X-axis (step S12). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, rotates the spindle 5 in the direction in which the first contact c1 faces the sixth measurement point P6, and moves the stylus 3b in the negative X-axis direction. Then, the sixth measurement point P6 is measured. When the first contact c1 contacts the sixth measured point P6 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the sixth measured point P6.

Next, the control unit 42 causes the stylus 3b to measure the seventh measurement point P7 on the Y axis (step S13). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, rotates the spindle 5 in the direction in which the first contact c1 faces the seventh measurement point P7, and moves the stylus 3b in the positive direction of the Y axis. The 7th measurement point P7 is measured. When the first contact c1 contacts the seventh measurement point P7 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the third measurement point P3.

Next, the control unit 42 causes the stylus 3b to measure the eighth measurement point P8 on the Y axis (step S14). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, rotates the spindle 5 in the direction in which the first contact c1 faces the eighth measurement point P8, and moves the stylus 3b in the negative direction on the Y axis. Then, the eighth measurement point P8 is measured. When the first contact c1 contacts the eighth measurement point P8 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the eighth measurement point P8.

Next, the control unit 42 lowers the stylus 3b by 3 mm in the Z-axis direction from the theoretical value center O of the machined hole HL (step S15). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, and then lowers the stylus 3b by 3 mm. As a result, the first contact c1 of the stylus 3b is positioned at a position where it can come into contact with the ninth measured point P9 to the twelfth measured point P12. In the present embodiment, 3 mm is described as an example of the amount of descent of the stylus 3b, but the amount of descent may be appropriately changed based on the design and the like.

Next, the control unit 42 causes the stylus 3b to measure the ninth measurement point P9 on the X-axis (step S16). More specifically, the control unit 42 measures the ninth measured point P9 by rotating the spindle 5 in the direction in which the first contact c1 faces the ninth measured point P9 and moving the stylus 3b in the positive direction of the X axis. Let me. When the first contact c1 contacts the ninth measured point P9 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the ninth measured point P9.

Next, the control unit 42 causes the stylus 3b to measure the tenth measurement point P10 on the X-axis (step S17). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, rotates the spindle 5 in the direction in which the first contact c1 faces the tenth measurement point P10, and moves the stylus 3b in the negative X-axis direction. Then, the tenth measurement point P10 is measured. When the first contact c1 contacts the tenth measurement point P10 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the tenth measurement point P10.

Next, the control unit 42 causes the stylus 3b to measure the eleventh measurement point P11 on the Y axis (step S18). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, rotates the spindle 5 in the direction in which the first contact c1 faces the eleventh measurement point P11, and moves the stylus 3b in the positive direction of the Y axis. The eleventh measurement point P11 is measured. When the first contact c1 contacts the eleventh measurement point P11 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the eleventh measurement point P11.

Next, the control unit 42 causes the stylus 3b to measure the twelfth measurement point P12 on the Y axis (step S19). More specifically, the control unit 42 returns the stylus 3b to the theoretical value center O, rotates the spindle 5 in the direction in which the first contact c1 faces the twelfth measurement point P12, and moves the stylus 3b in the negative direction on the Y axis. The twelfth measurement point P12 is measured. When the first contact c1 comes into contact with the twelfth measurement point P12 located on the inner peripheral surface of the machined hole HL, the stylus 3b measures the three-dimensional position of the twelfth measurement point P12. It should be noted that one of the processes of steps S10 to S14 and the processes of steps S15 to S19 may be omitted.

Next, as shown in FIG. 6, the control unit 42 calculates the measurement difference for each measurement point (step S20). Specifically, the control unit 42 calculates the measurement difference between the first measured point P1 and the fifth measured point P5 corresponding to the first measured point P1 with reference to the first measured point P1. Further, the control unit 42 calculates the measurement difference between the first measured point P1 and the ninth measured point P9 corresponding to the first measured point P1. The control unit 42 calculates the measurement difference for each of the second measured point P2, the third measured point P3, and the fourth measured point P4 in the same manner as the first measured point P1.

When the process of step S20 is completed, the control unit 42 then determines whether or not the measurement difference is less than 0.01 mm (step S21). More specifically, the control unit 42 determines whether or not all the calculated measurement differences are less than 0.01 mm. Thereby, it can be determined whether or not the first measurement point P1 or the like is measured with the stylus 3b biting the foreign matter.

When all the measurement differences are less than 0.01 mm (step S21: YES), the control unit 42 outputs a machining control signal (step S22), and ends the process. That is, if all the measurement differences are less than 0.01 mm, it is unlikely that the first measured point P1 or the like was measured with the stylus 3b biting a foreign object, and the second and subsequent workpieces WK. On the other hand, it can be processed in the same manner as the first workpiece WK. The machining control signal output from the control unit 42 is input to the machining center 30 via the communication unit 43.

On the other hand, when at least one measurement difference is 0.01 mm or more (step S21: NO), the control unit 42 outputs a measurement abnormality signal (step S23), and ends the process. That is, if at least one measurement difference is 0.01 mm or more, it is possible that the first measurement point P1 or the like is measured with the stylus 3b biting a foreign substance. Therefore, if the second and subsequent workpieces WK are machined in the same manner as the first workpiece WK, the position of the machined hole HL may shift. Therefore, the control unit 42 outputs a measurement abnormality signal and stops the machining center 30. The measurement abnormality signal output from the control unit 42 is input to the display unit 45. As a result, the display unit 45 displays an alarm such as equipment stop.

On the other hand, in the process of step S9 shown in FIG. 5, when the control unit 42 determines that the predetermined determination criterion is not satisfied (step S9: NO), the control unit 42 calculates the position difference at the center of the measured value (step S24). ). For example, when it is the second time since the power of the machining center 30 is turned on, the positional difference between the previous measured value center of the first time and the second measured value center calculated in the processes of steps S5 and S8 is calculated.

When the process of step S24 is completed, the control unit 42 then determines whether or not the position difference is less than 0.03 mm (step S25). More specifically, the control unit 42 determines whether or not the calculated position difference is less than 0.03 mm. This makes it possible to determine how much the center of the measured value this time deviates from the center of the measured value of the previous time. In the present embodiment, the threshold value to be compared with the position difference is 0.03 mm, but the threshold value may be appropriately changed depending on the design and the like.

If the positional difference is less than 0.03 mm (step S25: YES), the process of step S22 is executed and the process ends. That is, if the positional difference is less than 0.03 mm, the center of the measured value this time does not deviate so much from the center of the measured value of the previous time, and even if the center of the measured value of the previous time is adopted, the second and subsequent workpieces WK Can be processed in the same manner as the first workpiece WK.

On the other hand, when the position difference is 0.03 mm or more (step S25: NO), the process of step S23 is executed and the process is completed. That is, if the position difference is 0.03 mm or more, the center of the measured value this time deviates from the center of the measured value of the previous time, and if the center of the measured value of the previous time is adopted, 1 for the second and subsequent workpieces WK. If the machining is performed in the same manner as the geographic feature WK, the machining hole HL may be misaligned. Therefore, the control unit 42 outputs a measurement abnormality signal and stops the machining center 30.

As described above, in the measurement method according to the present embodiment, the first measurement points P1 defined at equal intervals on the circumference of the radial cross section in the cylindrical machined hole HL provided by processing the workpiece WK, The steps S5 and S8 for calculating the measured value center of the machined hole HL by sequentially contacting the stylus 3b with the second measured point P2, the third measured point P3, and the fourth measured point P4 are included. .. The measuring method includes step S9 for determining whether or not a predetermined determination criterion regarding the number of times of processing for the workpiece WK or the elapsed time from the previous processing is satisfied. In the measurement method, when a predetermined criterion is satisfied, the stylus 3b determines the fifth measured point P5 or the like corresponding to the first measured point P1 or the like in at least one other cross section other than the cross section parallel to the cross section. The measurement steps S11 to S14 and S16 to S19 are included. The measurement method calculates the measurement difference between the first measurement point P1 and the like and the fifth measurement point and the like for each corresponding measurement point, and measures when at least one of the measurement differences is 0.01 mm or more. The steps S20, S21, and S23 for outputting an abnormal signal are included. The measurement method is a step of calculating the position difference between the center of the previous measured value and the center of the current measured value when the predetermined judgment criteria are not satisfied, and outputting a measurement abnormality signal when the position difference is 0.03 mm or more. Includes S23-S25. Since the measurement abnormality signal is output when at least one of the measurement differences is 0.01 mm or more, or when the position difference is 0.03 mm or more, the measurement abnormality can be suppressed.

In particular, when the stylus 3b makes a measurement in a normal state where the stylus 3b is not tilted, calculates the hole diameter of the machined hole HL, and determines the presence or absence of a measurement abnormality based on the calculated hole diameter, the stylus 3b If the stylus 3b performs the measurement in an abnormal state in which the is tilted, the hole diameter cannot be calculated accurately, and as a result, the presence or absence of the measurement abnormality may not be accurately determined. However, according to the present embodiment, even in an abnormal state in which the stylus 3b is tilted, the center of the measured value is the same as in the normal state, so that the tilt of the stylus is not affected. Further, according to the present embodiment, since the stylus 3b measures not only one cross section but also a cross section different from the cross section, it is possible to accurately determine whether or not foreign matter is caught.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and modifications are made within the scope of the gist of the present invention described in the claims. It can be changed.

3 Touch probe 3b Suppressor 8 ATC
11 Tool Magazine 30 Machining Center 40 Control Device WK Work HL Machining Hole

Claims (1)

By sequentially bringing the stylus into contact with a plurality of first measurement points defined at equal intervals on the circumference of the first radial cross section in a cylindrical geographic hole provided by machining a workpiece. The step of calculating the center position of the machined hole and
A step of determining whether or not the criteria for the number of times the workpiece has been processed or the elapsed time since the previous processing is satisfied
When the determination criteria are satisfied, a plurality of second measured points corresponding to the first measured points in at least one second cross section other than the first cross section parallel to the first cross section are referred to. Steps to measure with a stylus and
The measurement difference between the first measurement point and the second measurement point is calculated for each corresponding measurement point, and at least one of the measurement differences is equal to or greater than the first threshold value at which a measurement abnormality can be determined. If, the step of outputting the measurement abnormality signal and
When the determination criterion is not satisfied, the position difference between the center position and the previous center position corresponding to the center position is calculated, and when the position difference is greater than or equal to the second threshold value larger than the first threshold value, the position difference is calculated. The step of outputting the measurement abnormality signal and
Measurement method including.

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