Measurement device and measurement method of measurement device

Abstract

To provide a measurement device and a measurement method of a measurement device which can enable a length measuring instrument to obtain a measured value under a condition which is more proper than before.SOLUTION: A measurement device comprises: a first measurement control part (a repeated measurement control part 33) that makes a length measuring instrument repeatedly obtain measured values, after either of the length measuring instrument (a laser length measuring instrument 21) and an object to be measured (a corner cube 18) starts to move to a measurement point; an index calculating part (a standard deviation calculating part 34) that repeatedly calculates an index representing variation of the measured values; a resting-start time determining part 35 that determines a time at which the index falls below a threshold, as a resting-starting time ST; a movement speed calculating part 36 that repeatedly calculates movement speed of the either one of them; a waiting time determining part 37 that determines a waiting time WT elapsing after the resting-start time ST, on the basis of information 50 on the movement speed of the either of them; and a second measurement control part (a post-movement measurement control part 38) that executes final measurement when the waiting time WT elapses after the resting-start time ST.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a measuring device equipped with a length measuring instrument, and a measuring method of the measuring device, which executes acquisition of a measurement value by the length measuring instrument when either the length measuring instrument or its measurement object is moved to a measurement point.

Background Art

[0002] Patent Document 1 discloses a measuring device used for measuring the movement accuracy (movement amount error and backlash) of the table of an NC (Numerically Control) machine tool. This measuring device includes a laser length measuring instrument. The laser length measuring instrument emits measurement light toward a corner cube arranged on the table, receives the reflected light of the measurement light reflected by the corner cube, and acquires a measurement value of the distance to the corner cube based on the received light signal of this reflected light.

[0003] When measuring the movement accuracy of the table, when the NC controller gives an instruction to move the table (corner cube) to the measurement point (measurement position) by the target movement amount with respect to the movement mechanism of the table, the actual movement amount of the table is calculated based on the measurement values acquired by the laser length measuring instrument before and after the movement. Thus, the movement accuracy of the table can be obtained by comparing the above-mentioned target movement amount with the actual movement amount of the table. At this time, if an external signal is used to determine the acquisition timing of the measurement value by the laser length measuring instrument after the movement of the table stops, there is a possibility that the acquisition of the measurement value by the laser length measuring instrument may be executed during the reverberation vibration of the table. Also, when the acquisition of the measurement values by the laser length measuring instrument before and after the movement of the table is performed at regular time intervals, there is a possibility that the laser length measuring instrument may acquire the measurement value regardless of whether the table is moving or stationary.

[0004] Therefore, in the measuring device described in Patent Document 1, before the stage (corner cube) moves to the measurement point, the acquisition of the measurement value by the laser length measuring instrument is repeatedly executed, and the movement of the stage to the measurement point is completed (the stage has stopped at the measurement point) is determined from the change state of the measurement value of the laser length measuring instrument. Specifically, based on the measurement values repeatedly acquired by the laser length measuring instrument, a chi-square test process of the moving speed of the stage is executed, and it is determined whether the stage has stopped at the measurement point based on whether the conditions preset by the operator (user) are satisfied. As a result, in the measuring device described in Patent Document 1, it is possible to automatically execute the acquisition of the measurement value by the laser length measuring instrument (this measurement) in a state where the stage has stopped at the measurement point.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in the measuring device described in the above Patent Document 1, when the conditions set by the operator are satisfied, it is determined that the stage (corner cube) has stopped at the measurement point, and this measurement by the laser length measuring instrument is automatically executed. At this time, if the conditions (threshold values) set by the operator are inappropriate, the laser length measuring instrument will acquire measurement values including variations unintended by the operator (for example, measurement values during reverberation vibration). In addition, depending on the setting of the conditions, the time until the start of this measurement by the laser length measuring instrument may be unnecessarily extended, and there is a possibility that the measurement time will become long.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a measuring device and a measuring method for the measuring device capable of executing the acquisition of the measurement value by the length measuring instrument under more appropriate conditions than in the prior art.

Means for Solving the Problems

[0008] A measuring device for achieving the object of the present invention includes a length measuring device that obtains a measurement value of a distance to a measurement object, and executes acquisition of the measurement value by the length measuring device when either the length measuring device or the measurement object is moved to a predetermined measurement point, the measuring device including a first measurement control unit that repeatedly executes acquisition of the measurement value by the length measuring device after movement to one of the measurement points has started, an index calculation unit that repeatedly calculates an index representing the variation in the measurement values ​​based on the measurement values ​​repeatedly obtained by the length measuring device, and a time period during which the index calculated by the index calculation unit becomes equal to or less than a predetermined threshold value when one of the measurement points is stationary. The measuring device includes a rest start time determination unit that determines the rest start time as the rest stop start time, a movement speed calculation unit that repeatedly calculates one of the movement speeds based on the measurement values ​​repeatedly acquired by the length measuring device and the measurement value acquisition interval, a waiting time determination unit that determines a waiting time from the rest start time determined by the rest start time determination unit to the time when the length measuring device starts actual measurement of the measurement value at the measurement point based on one of the movement speed information obtained from the calculation result of the movement speed calculation unit, and a second measurement control unit that executes the actual measurement by the length measuring device when the waiting time determined by the waiting time determination unit has elapsed from the rest start time determined by the rest start time determination unit.

[0009] According to this measuring device, an appropriate waiting time can be automatically determined according to the moving speed information.

[0010] In a measurement device according to another aspect of the present invention, the moving speed information includes at least one of a maximum value of the moving speed and a time change of the moving speed during deceleration, whereby an appropriate waiting time can be automatically determined according to at least one of the maximum value of the moving speed and the time change during deceleration.

[0011] In a measuring device according to another aspect of the present invention, the index calculation unit performs calculation of the index at a predetermined fixed time interval based on a plurality of measurement values ​​acquired by the length measuring device within the fixed time interval, thereby making it possible to determine whether one of the measuring devices has become stationary.

[0012] In the measurement device according to another aspect of the present invention, the index calculation unit calculates the standard deviation of the measurement values ​​as the index, thereby making it possible to determine whether one of the two has become stationary.

[0013] In the measurement device according to another aspect of the present invention, the waiting time determination unit determines the waiting time using a trained model that receives moving speed information as an input and outputs a waiting time, thereby making it possible to automatically determine an appropriate waiting time according to the moving speed information.

[0014] A measuring device according to another aspect of the present invention includes a movement control unit that drives a movement mechanism that moves one of the two to a measurement point.

[0015] A measurement method for a measuring device for achieving the object of the present invention includes a length measuring device that obtains measured values ​​of a distance to a measurement object, and executes acquisition of a measured value by the length measuring device when either the length measuring device or the measurement object is moved to a predetermined measurement point, the measurement method includes a first measurement control step of repeatedly executing acquisition of a measured value by the length measuring device after movement to one of the measurement points has started, an index calculation step of repeatedly calculating an index that represents the variation in the measured values ​​repeatedly obtained by the length measuring device, a rest start time determination step of determining a time when the index calculated in the index calculation step becomes equal to or smaller than a predetermined threshold as the rest start time at which one of the objects becomes restless at the measurement point, a moving speed calculation step of repeatedly calculating the moving speed of one of the objects based on the measured values ​​repeatedly obtained by the length measuring device and the interval between acquisition of the measured values, a waiting time determination step of determining a waiting time from the rest start time determined in the rest start time determination step until the length measuring device starts actual measurement of the measured value at the measurement point based on moving speed information of the one of the objects obtained from the calculation result in the moving speed calculation step, and and a second measurement control step of executing a main measurement by the length measuring device when the waiting time determined in the waiting time determining step has elapsed from the determined rest start time. Effect of the Invention

[0016] The present invention makes it possible to obtain measured values ​​using a length measuring device under more appropriate conditions than in the past. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram of an NC machine tool and a measuring device of the present invention used to measure the accuracy of the NC machine tool. [Diagram 2] FIG. 2 is a functional block diagram of a control device. [Diagram 3] 3 is a graph showing a first movement example and a second movement example (see reference symbol 3B) of the stage in the X direction when measuring the movement accuracy of the stage. [Figure 4] 11 is a graph showing a change over time in standard deviation repeatedly calculated by a standard deviation calculation unit during repeated measurements by the laser length measuring device. [Diagram 5] 11 is a graph showing the change over time in the moving speed of the stage repeatedly calculated by a moving speed calculation unit during repeated measurements by the laser length measuring device. [Figure 6] 11 is a graph for explaining a waiting time determined by a waiting time determination unit. [Figure 7] FIG. 1 is an explanatory diagram showing an example of training data used in machine learning of a trained model. [Figure 8] FIG. 11 is an explanatory diagram for explaining an example of determining a waiting time by a waiting time determination unit using a trained model. [Figure 9] 11 is a flowchart showing the flow of a process for measuring the movement accuracy of a stage of an NC machine tool by a measuring device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] [Configuration of NC machine tools] 1 is a schematic diagram of an NC machine tool 10 and a measuring device 20 of the present invention used for measuring the accuracy of the NC machine tool 10. Of the mutually orthogonal X, Y and Z directions in the figure, the X and Y directions are parallel to the horizontal direction, and the Z direction is parallel to the vertical direction.

[0019] 1, the NC machine tool 10 is a machining center capable of continuously performing a variety of processes, such as boring, milling, drilling, tapping, and reaming. The NC machine tool 10 includes a machining tool holder 11, a holder movement mechanism 12, a stage 13, a stage movement mechanism 14, and an NC controller 15.

[0020] The processing tool holder 11 holds and drives various processing tools for processing a workpiece (not shown). The holder movement mechanism 12 is a known actuator that holds the processing tool holder 11 movably in the Z direction (up and down direction).

[0021] A workpiece (not shown) is placed on the stage 13 when the workpiece is processed. A corner cube 18 is placed on the stage 13 when measuring the movement accuracy of the stage 13 etc., which will be described later. The corner cube 18 moves integrally with the stage 13, and therefore corresponds to the measurement object of the present invention together with the stage 13. Note that instead of the corner cube 18, another reflector may be placed on the stage 13. The stage movement mechanism 14 is a known actuator that holds the stage 13 so that it can move freely in the X and Y directions.

[0022] The NC controller 15 controls the driving of the machining tool by the machining tool holder 11, the movement of the machining tool holder 11 by the holder moving mechanism 12, and the movement of the stage 13 by the stage moving mechanism 14, etc.

[0023] [Measurement device configuration] The measuring device 20 measures the movement accuracy (movement amount error and backlash) of the stage 13 in accordance with the provisions for movement amount error and backlash of ISO230-2 or JIS-B-6201 (see Patent Document 1 above). Specifically, the measuring device 20 measures the actual movement amount of the corner cube 18 placed on the stage 13, that is, the actual movement amount of the stage 13, when the NC controller 15 instructs the stage movement mechanism 14 to move the stage 13 by the target movement amount to a specified measurement point.

[0024] The measuring device 20 can also measure the movement accuracy of the processing tool holding part 11, that is, the actual movement amount of the processing tool holding part 11 when the NC controller 15 instructs the holder moving mechanism 12 to move the processing tool holding part 11 by a target movement amount to a predetermined measurement point. Note that in this specification, the measurement of the movement accuracy of the stage 13 by the measuring device 20 will be described as an example.

[0025] The measuring device 20 includes a laser length measuring device 21 and a control device 30. The laser length measuring device 21 corresponds to the length measuring device of the present invention, and includes a laser light source 22, a laser interference unit 24, a signal processing unit 26, and optical fiber cables 28A and 28B. The laser light source 22 and the laser interference unit 24 are connected via the optical fiber cable 28A, and the laser interference unit 24 and the signal processing unit 26 are connected via the optical fiber cable 28B.

[0026] The laser light source 22 emits measurement light L1, which is a laser light, to the laser interference unit 24 via an optical fiber cable 28A.

[0027] The laser interference unit 24 (also called a sensor head) is detachably held by the processing tool holding part 11, and emits measurement light L1 incident from the laser light source 22 via an optical fiber cable 28A in the X direction toward the corner cube 18 on the stage 13. As a result, reflected light L2 of the measurement light L1 reflected by the corner cube 18 is incident on the laser interference unit 24. The laser interference unit 24 then generates interference light L3 between the reflected light L2 and a portion (reference light) of the measurement light L1 reflected by a reference surface (not shown), and emits this interference light L3 to the signal processing unit 26 via the optical fiber cable 28B.

[0028] The signal processing unit 26 receives the interference light L3 incident from the laser interference unit 24 via the optical fiber cable 28B. Then, the signal processing unit 26 calculates a measurement value of the distance between the laser interference unit 24 and the corner cube 18 (hereinafter abbreviated as the measurement value) using a known method based on the reception signal of the received interference light L3, and outputs the calculation result of this measurement value to the control device 30.

[0029] When measuring the movement accuracy of the stage 13, the laser length measuring device 21, under the control of the control device 30 described below, executes a main measurement to obtain measurement values ​​before the stage 13 (corner cube 18) is moved by the stage moving mechanism 14 and after (when stationary) the stage 13 has been moved by the stage moving mechanism 14. Hereinafter, the main measurement before the stage 13 is moved is referred to as the pre-movement main measurement, and the main measurement after the stage 13 has been moved is referred to as the post-movement main measurement.

[0030] Further, under the control of the control device 30, the laser length measuring device 21 performs repeated measurement (also called continuous measurement) in which measurement values ​​are repeatedly acquired from the time when the stage moving mechanism 14 starts moving the stage 13 (corner cube 18) until the stage 13 comes to a stop. Here, the measurement values ​​repeatedly acquired by the laser length measuring device 21 are used in a determination process in which the control device 30 determines whether the stage 13 has come to a stop, and in a determination process of the timing to perform the main measurement after the movement of the stage 13 is completed.

[0031] The control device 30 includes an arithmetic circuit configured with various processors and memories, etc. The various processors include a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), and a programmable logic device (e.g., simple programmable logic devices (SPLD), complex programmable logic devices (CPLD), and field programmable gate arrays (FPGA)). The various functions of the control device 30 may be realized by one processor, or may be realized by multiple processors of the same or different types.

[0032] The control device 30 is connected to the NC controller 15, the laser light source 22, and the signal processing unit 26 via a signal cable (not shown). The control device 30 controls the operation of the NC controller 15 and the laser length measuring device 21 (laser light source 22, signal processing unit 26) when measuring the movement accuracy of the stage 13, thereby controlling the movement of the stage 13 by the stage moving mechanism 14 and the acquisition of measurement values ​​by the laser length measuring device 21.

[0033] Fig. 2 is a functional block diagram of the control device 30. As shown in Fig. 2, the control device 30 executes a program read from a memory (not shown) to function as a pre-movement measurement control unit 31, a movement control unit 32, a repeated measurement control unit 33, a standard deviation calculation unit 34, a rest start time determination unit 35, a movement speed calculation unit 36, a waiting time determination unit 37, a post-movement measurement control unit 38, and a measurement value storage unit 39.

[0034] For example, when an operation to start measuring the movement accuracy of the stage 13 is input to an operation unit (not shown) of the control device 30, the pre-movement measurement control unit 31 controls the laser length measuring device 21 to execute the pre-movement main measurement. As a result, before the stage 13 (corner cube 18) starts moving, the laser length measuring device 21 acquires a measurement value for measuring the movement accuracy of the stage 13.

[0035] For example, when the main measurement before moving the stage 13 is completed, the movement control unit 32 generates an NC program 32a for moving the stage 13 in the X direction (or in the Y direction) to a measurement point away by an amount of movement corresponding to a test method specified in ISO230-2, JIS-B-6201, etc. Then, the movement control unit 32 outputs the NC program 32a to the NC controller 15.

[0036] 3 is a graph showing a first movement example (see reference symbol 3A) and a second movement example (see reference symbol 3B) of the stage 13 in the X direction when measuring the movement accuracy of the stage 13. The horizontal axis of each graph represents time (msec), and the vertical axis represents the displacement amount (mm) of the stage 13 in the X direction. As shown in FIG. 3, the NC controller 15 drives the stage movement mechanism 14 in accordance with the NC program 32a to move the stage 13 (corner cube 18) in the X direction toward the measurement point, and stops the stage 13 at the measurement point.

[0037] Note that the operator may directly input an instruction to move the stage 13 in the X direction (or the Y direction) by the above-mentioned movement amount to the NC controller 15. In this case, the movement control unit 32 can be omitted.

[0038] Returning to Fig. 2, the repeated measurement control unit 33 corresponds to the first measurement control unit of the present invention. The repeated measurement control unit 33 executes repeated measurements by the laser length measuring device 21 after the stage moving mechanism 14 starts moving the stage 13 (corner cube 18). This causes the laser length measuring device 21 to repeatedly obtain measured values ​​of the distance to the corner cube 18 at least while the stage 13 is moving. The repeated measurements by the laser length measuring device 21 continue, for example, until the stage moving mechanism 14 stops moving the stage 13, or until the rest start time determining unit 35, described below, determines the rest start time ST (see Fig. 6).

[0039] The interval at which the laser length measuring device 21 obtains the measured values ​​in the repeated measurements is used to calculate the moving speed of the stage 13 by the moving speed calculation unit 36, which will be described later. Therefore, in order to obtain accurate measuring value obtaining intervals, it is preferable that the repeated measurements (sampling of the measured values) by the laser length measuring device 21 are performed in accordance with a reference clock output from a signal generator (not shown).

[0040] Fig. 4 is a graph showing the change over time of the standard deviation repeatedly calculated by the standard deviation calculation unit 34 during repeated measurements by the laser length measurement device 21. Reference numeral 4A in Fig. 4 indicates the change over time of the standard deviation when the stage 13 is moved to the measurement point according to the first movement example shown by reference numeral 3A in Fig. 3 described above. Reference numeral 4B in Fig. 4 indicates the change over time of the standard deviation when the stage 13 is moved to the measurement point according to the second movement example shown by reference numeral 3B in Fig. 3 described above.

[0041] As shown in Fig. 4 and the above-mentioned Fig. 2, the standard deviation calculation unit 34 corresponds to the index calculation unit of the present invention. This standard deviation calculation unit 34 acquires and temporarily stores the measurement values ​​from the laser length measuring device 21 within a predetermined fixed time interval while the stage 13 is moving, and calculates a standard deviation based on the multiple measurement values ​​temporarily stored. The standard deviation is an index that represents the variation in the measurement values ​​within a fixed time interval. Note that instead of calculating the standard deviation of the measurement values, another index that represents the variation in the measurement values ​​may be calculated.

[0042] The rest start time determination unit 35 determines the rest start time ST (see Figure 6) at which the stage 13 (corner cube 18) comes to rest at the measurement point, based on the standard deviation that the standard deviation calculation unit 34 repeatedly calculates at regular time intervals while the stage 13 is moving.

[0043] Specifically, the change in the measured value becomes large while the stage 13 (corner cube 18) is moving to the measurement point, so the standard deviation calculated by the standard deviation calculation unit 34 becomes large. On the other hand, when the stage 13 stops at the measurement point, only the variation caused by the vibration of the corner cube 18 and the environmental disturbance occurs, so the standard deviation becomes small. Therefore, by setting a threshold value Th (see FIG. 6) for the standard deviation calculated by the standard deviation calculation unit 34, the rest start time determination unit 35 can determine whether the stage 13 has stopped based on whether the standard deviation newly calculated by the standard deviation calculation unit 34 is equal to or smaller than the threshold value Th. The threshold value Th is appropriately determined by performing an experiment or a simulation.

[0044] Then, the rest start time determination unit 35 determines the time when the standard deviation newly calculated by the standard deviation calculation unit 34 becomes equal to or smaller than the threshold value Th as the rest start time ST (see FIG. 6).

[0045] Fig. 5 is a graph showing the change over time in the moving speed of the stage 13, which is repeatedly calculated by the moving speed calculation unit 36 ​​during repeated measurements by the laser length measurement device 21. Reference numeral 5A in Fig. 5 indicates the change over time in the moving speed of the stage 13 while the stage 13 is moved to the measurement point according to the first moving example shown by reference numeral 3A in Fig. 3 described above. Reference numeral 5B in Fig. 5 indicates the change over time in the moving speed of the stage 13 while the stage 13 is moved to the measurement point according to the second moving example shown by reference numeral 3B in Fig. 3 described above.

[0046] 5 and the above-described FIG. 2, the movement speed calculation unit 36 ​​repeatedly executes calculation of the movement speed of the stage 13 (corner cube 18) while the stage 13 is moving (during repeated measurements by the laser length measurement device 21). For example, every time the laser length measurement device 21 acquires a new measurement value, the movement speed calculation unit 36 ​​repeatedly calculates the movement speed of the stage 13 based on the newly acquired measurement value, the measurement value acquired immediately before that, and the measurement acquisition interval (known information). The calculation result of the movement speed calculation unit 36 ​​is used by the waiting time determination unit 37, which will be described later, to determine the waiting time WT (see FIG. 6).

[0047] 6 is a graph for explaining the waiting time WT determined by the waiting time determination unit 37. The symbol Q in the figure indicates the start timing of the main measurement after movement. The symbol MS in the figure indicates the moving state of the stage 13 before the rest start time ST, and the symbol SS in the figure indicates the rest state of the stage 13 after the rest start time ST.

[0048] 6 and the above-mentioned FIG. 2, the waiting time determination unit 37 determines the waiting time WT from the rest start time ST determined by the rest start time determination unit 35 until the start of the main measurement after the movement. Conventionally (see Patent Document 1 above), the waiting time WT was determined based on conditions preset by the operator. If these conditions are inappropriate, the laser length measuring device 21 may obtain a measurement value during reverberation vibration of the stage 13, or the time until the start of the main measurement after the movement may be unnecessarily extended.

[0049] Here, the present inventors have found that the appropriate waiting time WT changes depending on the behavior of the stage 13 until it moves to the measurement point, specifically, the change in the moving speed of the stage 13 (see FIG. 5). Therefore, the waiting time determination unit 37 automatically determines an appropriate waiting time WT by referring to a trained model 37a created in advance, based on moving speed information 50 of the stage 13 obtained from the calculation result of the moving speed calculation unit 36 ​​(see FIG. 7).

[0050] The trained model 37a is generated by using, for example, machine learning (supervised learning) using a known multiple regression model (multiple regression equation, multiple regression analysis) or a machine learning algorithm such as a known convolutional neural network (CNN). As shown in Fig. 8 described later, the trained model 37a uses moving speed information 50 of the stage 13 as input data (input variable) and outputs a waiting time WT, which is a response variable.

[0051] Fig. 7 is an explanatory diagram showing an example of teacher data 52 used for machine learning of the trained model 37a. As shown in Fig. 7, as the teacher data 52 (training data), a data group including moving speed information 50 for each condition and an optimal waiting time WT (correct label) when the stage 13 is moved to a measurement point under various moving speed conditions is used.

[0052] The moving speed information 50 includes, for example, a maximum value P1 of the moving speed of the stage 13, and a time change P2 (acceleration) of the moving speed of the stage 13 while the moving speed of the stage 13 is being decelerated. As the time change P2, it is preferable to use the time change P2 when the moving speed of the stage 13 is suddenly decelerated near the measurement point. Furthermore, the time change P2 that is the subject of the moving speed information 50 is not limited to one point as shown in FIG. 7, but may be multiple points. Note that instead of including both the maximum value P1 and the time change P2, the moving speed information 50 may include only one of the maximum value P1 and the time change P2.

[0053] The trained model 37a is generated by the above-mentioned machine learning algorithm based on such teacher data 52. Note that the machine learning algorithm is a well-known technique, and therefore a detailed description thereof will be omitted here. In addition, in the present embodiment, supervised learning has been exemplified as the machine learning of the trained model 37a, but unsupervised learning, reinforcement learning, transfer learning, and the like may also be performed as the machine learning.

[0054] Fig. 8 is an explanatory diagram for explaining an example of determination of waiting time WT by waiting time determination unit 37 using trained model 37a. As shown in Fig. 8, waiting time determination unit 37 detects movement speed information 50 (maximum value P1, time change P2) based on the movement speed of stage 13 repeatedly calculated by movement speed calculation unit 36 ​​while stage 13 is moving (see Figs. 5 and 7). Then, waiting time determination unit 37 inputs movement speed information 50 to trained model 37a to output waiting time WT.

[0055] Returning to Figures 2 and 6, the post-movement measurement control unit 38 (corresponding to the second measurement control unit of the present invention) performs the post-movement main measurement when the waiting time WT has elapsed from the rest start time ST, i.e., at start timing Q, based on the rest start time ST determined by the rest start time determination unit 35 and the waiting time WT determined by the waiting time determination unit 37.

[0056] The measurement value storage unit 39 stores the measurement values ​​measured by the laser length measuring device 21 in the pre-movement main measurement and the post-movement main measurement as data for checking the movement accuracy of the stage 13.

[0057] [Measuring device function] FIG. 9 is a flowchart showing the flow of a process (measurement method) for measuring the movement accuracy of the stage 13 of the NC machine tool 10 by the measuring device 20.

[0058] 9, after setting the corner cube 18 on the stage 13, when the operator operates the operation section (not shown) of the control device 30 to start measuring the movement accuracy of the stage 13, the pre-movement measurement control section 31 controls the laser length measuring device 21 to perform the pre-movement main measurement (step S1). The measurement value measured by the laser length measuring device 21 in the pre-movement main measurement is stored in the measurement value memory section 39.

[0059] When the pre-movement main measurement is completed, the movement control unit 32 generates an NC program 32a for moving the stage 13 in the X direction to the measurement point, and outputs this NC program 32a to the NC controller 15. As a result, the NC controller 15 drives the stage moving mechanism 14 based on the NC program 32a to move the stage 13 in the X direction toward the measurement point (step S2A, NO in step S2B). Then, the NC controller 15 stops the stage 13 at the measurement point based on the detection result of a position detection sensor (not shown) (YES in step S2B, step S2C).

[0060] When the movement of the stage 13 by the stage moving mechanism 14 is started, the repetitive measurement control unit 33 causes the laser length measuring device 21 to start repetitive measurement. As a result, acquisition of measurement values by the laser length measuring device 21 is repeatedly executed (step S3A, corresponding to the first measurement control step of the present invention). The measurement values repeatedly acquired by the laser length measuring device 21 are sequentially output to the standard deviation calculation unit 34 and the moving speed calculation unit 36.

[0061] When the repetitive measurement is started, the standard deviation calculation unit 34 repeatedly executes temporary storage of the measurement values acquired by the laser length measuring device 21 within a fixed time interval and calculation of the standard deviation of the temporarily stored measurement values at every fixed time interval (step S3B, corresponding to the index calculation step of the present invention). Also, the moving speed calculation unit 36 repeatedly executes calculation of the moving speed of the stage 13 each time the laser length measuring device 21 acquires a new measurement value (step S3B, corresponding to the moving speed calculation step of the present invention).

[0062] Then, the stationary start time determination unit 35 monitors whether or not the standard deviation calculated by the standard deviation calculation unit 34 at every fixed time interval becomes equal to or less than the threshold value Th (NO in step S4). Then, as shown in FIG. 6 described above, the stationary start time determination unit 35 determines the time when the newly calculated standard deviation by the standard deviation calculation unit 34 becomes equal to or less than the threshold value Th as the stationary start time ST, and outputs this stationary start time ST to the post-movement measurement control unit 38 (step S5, corresponding to the stationary start time determination step of the present invention).

[0063] Also, the waiting time determination unit 37 detects movement speed information 50 (maximum value P1, time change P2) based on the movement speed of the stage 13 repeatedly calculated by the movement speed calculation unit 36. Then, as shown in FIG. 8 described above, the waiting time determination unit 37 inputs the detected movement speed information 50 to the learned model 37a, and outputs the waiting time WT to the post-movement measurement control unit 38 (step (Step S6, which corresponds to a waiting time determining step of the present invention). As a result, an appropriate waiting time WT is automatically determined according to the moving speed information 50 without the operator setting any conditions. Note that the timing at which the waiting time determining unit 37 determines the waiting time WT may be earlier than the timing at which the rest start time determining unit 35 determines the rest start time ST.

[0064] The post-movement measurement control unit 38, which has received the input of the rest start time ST and the waiting time WT, monitors whether the waiting time WT has elapsed from the rest start time ST (NO in step S7). Then, as shown in Fig. 6, the post-movement measurement control unit 38 controls the laser length measuring device 21 at the start timing Q when the waiting time WT has elapsed from the rest start time ST to execute the main measurement after movement (step S8, which corresponds to the second measurement control unit step of the present invention).

[0065] The measurement value measured by the laser length measuring device 21 in the main measurement after the movement is stored in the measurement value storage unit 39 (step S9). As a result, the movement accuracy of the stage 13 (the difference between the target movement amount and the actual movement amount) is obtained based on the measurement values ​​of the main measurement before the movement and the main measurement after the movement stored in the measurement value storage unit 39. At this time, the control device 30 may calculate the movement accuracy of the stage 13 based on the measurement values ​​stored in the measurement value storage unit 39 and display it on a display unit (not shown).

[0066] When the movement of the stage 13 to the next measurement point and the main measurement after the movement at the next measurement point are repeatedly performed, the above-mentioned processes from step S1 to step S9 are repeatedly performed. In this case, the accuracy measurement of the NC machine tool 10 requires that the intervals between the measurement points (measurement intervals) be made uneven (ISO230-2). This means that there is a difference in the maximum value P1 of the movement speed of the stage 13 between the measurement points, but in the present invention, an appropriate waiting time WT can be automatically determined according to the movement speed information 50.

[0067] As described above, the measuring device 20 of this embodiment detects the moving speed information 50 of the stage 13 while it is moving and inputs the information to the trained model 37a, thereby determining an appropriate waiting time WT corresponding to the moving speed information 50 of the stage 13. This automatically determines an appropriate waiting time WT without the operator having to set any conditions, preventing the laser length measuring device 21 from acquiring measured values ​​at the measurement point that include variations unintended by the operator and preventing the start time of the actual measurement after movement from being unnecessarily extended. As a result, it is possible to acquire measured values ​​at the measurement point by the laser length measuring device 21 under more appropriate conditions than before.

[0068] When measuring the movement accuracy of the processing tool holder 11 in the Z direction using the measuring device 20, for example, the emission direction of the measurement light L1 from the laser interference unit 24 held by the processing tool holder 11 is switched to the downward Z direction, and the corner cube 18 is set below the laser interference unit 24 in the Z direction. Then, the control device 30 controls the NC controller 15 to move the processing tool holder 11 in the Z direction to a predetermined measurement point, and causes the laser length measuring device 21 to perform main measurement before and after the movement. In this case, as in the case of measuring the movement accuracy of the stage 13, the main measurement after the movement using the laser length measuring device 21 can be performed under appropriate conditions.

[0069] [others] In the above embodiment, the moving body (load stage 13, machining tool holding part 11) of the NC machine tool 10 whose movement accuracy is to be measured and the reflector that reflects the measurement light L1 emitted from the laser length measuring instrument 21 (the object whose distance is to be measured by the laser length measuring instrument 21) are separate bodies, but the moving body and the reflector may be integrated, or a part of the moving body may be used as the reflector.

[0070] In the above embodiment, for example, when measuring the movement accuracy of the stage 13, the corner cube 18 is moved together with the stage 13. However, if the corner cube 18 is provided in the processing tool holder 11 instead of the laser length measuring device 21, the laser length measuring device 21 is moved together with the stage 13. That is, it is only necessary to move either the laser length measuring device 21 or the object to be measured.

[0071] In the above embodiment, the laser length measuring device 21 has been used as an example of a length measuring device for measuring the distance to a measurement object such as a corner cube 18, but various well-known length measuring devices that measure the distance to a measurement object using other measurement methods may be used instead of the laser length measuring device 21.

[0072] In the above embodiment, the control device 30 of the measuring device 20 is provided separately from the NC machine tool 10. However, for example, a control unit (not shown) of the NC machine tool 10 may function as the control device 30.

[0073] In the above embodiment, the waiting time determination unit 37 determines the waiting time WT by inputting the moving speed information 50 into the trained model 37a. However, instead of the trained model 37a, the waiting time WT may be determined based on a data table or an arithmetic formula, etc., which shows the relationship between the moving speed information 50 and the waiting time WT that has been generated in advance.

[0074] In the above embodiment, the measurement of the movement accuracy of each part of the NC machine tool 10 by the measuring device 20 has been described as an example, but the present invention can be applied to measuring the movement accuracy of a moving body (moving mechanism) of various shape measuring devices including a non-contact shape measuring device and a contact shape measuring device. Furthermore, the measuring device 20 of the present invention can also be applied to measuring the movement accuracy of a moving body provided in various devices or mechanisms. [Explanation of symbols]

[0075] 10...NC machine tool, 11...machining tool holder, 12...holder moving mechanism, 13...workpiece stage, 14...workpiece stage moving mechanism, 15...NC controller, 18...corner cube, 20...measuring device, 21...laser length measuring device, 22...laser light source, 24...laser interference unit, 26...signal processing unit, 28A...optical fiber cable, 28B...optical fiber cable, 30...control device, 31...pre-movement measurement control unit, 32...movement control unit, 32a...NC program, 33...repetitive measurement control unit, 34...standard deviation calculation unit, 35...rest start time determination unit, 36...movement speed calculation unit, 37...time determination unit, 37a...trained model, 38...post-movement measurement control unit, 39...measurement value memory unit, 50...movement speed information, 52...teaching data, L1...measurement light, L2...reflected light, L3...interference light, P1...maximum value, P2...change over time, Q...start timing, ST...rest start time, Th...threshold

Claims

1. A measuring device includes a length measuring device for acquiring a measured value of a distance to a measurement object, and acquires the measured value by the length measuring device when either the length measuring device or the measurement object is moved to a predetermined measurement point, a first measurement control unit that repeatedly executes acquisition of the measurement value by the length measuring device after movement to the one of the measurement points is started; an index calculation unit that repeatedly calculates an index that represents a variation in the measurement values ​​based on the measurement values ​​repeatedly obtained by the length measuring device; a rest-start time determination unit that determines a time when the index calculated by the index calculation unit becomes equal to or smaller than a predetermined threshold as a rest-start time when the one of the sensors is at the measurement point; a moving speed calculation unit that repeatedly calculates the moving speed of the one of the objects based on the measurement values ​​repeatedly acquired by the length measuring device and the acquisition intervals of the measurement values; a waiting time determination unit that determines a waiting time from the rest start time determined by the rest start time determination unit until the length measuring device starts actual measurement of the measurement value at the measurement point, based on the one of the moving speed information obtained from the calculation result of the moving speed calculation unit; a second measurement control unit that executes the main measurement by the length measuring device when the waiting time determined by the waiting time determination unit has elapsed from the rest start time determined by the rest start time determination unit; A measuring device comprising:

2. The measuring device according to claim 1 , wherein the moving speed information includes at least one of a maximum value of the moving speed and a time change of the moving speed during deceleration of the moving speed.

3. 3. The measuring device according to claim 1, wherein the index calculation unit calculates the index at predetermined time intervals based on a plurality of the measurement values ​​obtained by the length measuring device within the predetermined time interval.

4. The measurement device according to claim 3 , wherein the index calculation unit calculates a standard deviation of the measurement values ​​as the index.

5. The measurement device according to claim 1 or 2, wherein the waiting time determination unit determines the waiting time using a trained model that receives the moving speed information as an input and outputs the waiting time.

6. The measuring device according to claim 1 , further comprising a movement control unit that drives a movement mechanism that moves the one of the components to a measurement point.

7. A measurement method for a measuring device including a length measuring device for obtaining a measurement value of a distance to a measurement object, the measurement value being obtained by the length measuring device when either the length measuring device or the measurement object is moved to a predetermined measurement point, comprising: a first measurement control step of repeatedly acquiring the measurement value by the length measuring device after the movement to the one of the measurement points is started; an index calculation step of repeatedly calculating an index representing a variation in the measurement values ​​repeatedly obtained by the length measuring device; a rest-start time determining step of determining a time when the index calculated in the index calculating step becomes equal to or less than a predetermined threshold as a rest-start time when the one of the two is stationary at the measurement point; a moving speed calculation step of repeatedly calculating the moving speed of the one of the two objects based on the measurement values ​​repeatedly obtained by the length measuring device and the intervals at which the measurement values ​​are obtained; Based on the one of the moving speed information obtained from the calculation result of the moving speed calculation step, a waiting time determining step of determining a waiting time from the rest start time determined in the rest start time determining step until the length measuring device starts actual measurement of the measurement value at the measurement point; a second measurement control step of executing the main measurement by the length measuring device when the waiting time determined in the waiting time determining step has elapsed from the rest start time determined in the rest start time determining step; A measuring method for a measuring device having the above structure.

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