Coordinate measuring machine and computer readable storage medium

Abstract

The present invention provides a coordinate measuring machine and a computer-readable storage medium. The coordinate measuring machine can shorten the time from power-on to completion of measurement preparation without impairing the high-precision measurement function. The coordinate measuring machine includes: a platform; a probe moving body; an INC pattern and an ABS pattern along the moving direction of the probe moving body; an INC detector that outputs a number of waveform signals corresponding to the movement amount according to the INC pattern; an ABS detector that outputs the absolute position of the probe moving body according to the ABS pattern in response to a request signal; and a control device. The control device includes: a counting unit that counts the output waveform signal; a position information acquisition unit that reads the count value at the detection timing of detecting a workpiece; and a preset unit that sends a request signal to the ABS detector and acquires an absolute position signal, and presets the absolute position signal to the counting unit.

Description

[0001] [Related Application]

[0002] This application claims the benefit of Japanese Patent Application No. 2019-105359 filed on June 5, 2019, which is hereby incorporated by reference. Technical Field

[0003] The present invention relates to a technology for shortening the time from power-on to completion of measurement preparation in a coordinate measuring machine such as a three-dimensional measuring machine. Background Art

[0004] In recent years, there has been an increasing demand for important inspection items related to product quality to inspect all products. Therefore, there is a great demand for devices such as coordinate measuring machines that are responsible for important measurements related to product quality to not only improve measurement accuracy but also shorten measurement time.

[0005] Generally, a coordinate measuring machine includes a probe moving body configured to move a probe relative to a workpiece in three axial directions, such as the X, Y, and Z axes. Based on a probe signal sent by the probe when the workpiece is detected, the coordinate measuring machine reads position information of the probe moving body from a scale provided in each axial direction. The coordinate measuring machine is configured to measure the three-dimensional shape of the workpiece by analyzing this position information.

[0006] In order to improve the measurement efficiency of the coordinate measuring machine, that is, to shorten the measurement time, it is effective not only to increase the speed and acceleration / deceleration of the probe moving body but also to shorten the time from power-on of the device to completion of measurement preparation.

[0007] Usually, a coordinate measuring machine reads the position information of the probe movable body from an incremental type (hereinafter referred to as INC type) scale. Due to the characteristics of the INC type scale, an origin return operation is required when the power is turned on. This operation is to move the probe movable body to a preset origin and return the probe movable body to the origin.

[0008] For example, in a well-known processing device that requires high-precision positioning, according to the description of paragraph 0033 of patent document 1, when the origin return operation of the processing head is performed at startup, its position control unit performs control to return the processing head to a specified origin based on the current absolute position information obtained from the absolute type (hereinafter referred to as ABS type) scale. More specifically, according to the description of paragraph 0035 of patent document 1, after the power is turned on, the position control unit obtains the approximate absolute position information of the processing head from the ABS type scale of the processing head. The approximate position is "temporarily preset" to the INC type scale. Then, based on the acquired absolute position, the processing head is moved to the detection start point of the origin mark. Moreover, the processing head is moved in a certain direction of the origin mark, and at the moment the origin mark is detected, the value of the INC type scale is "officially preset" to a pre-set value. Thereafter, the position control of the processing head is performed based on the value from the INC type scale with high control accuracy.

[0009] The purpose of using the INC type scale and the ABS type scale together in Patent Document 1 is to omit the position detection operation using the conventional mechanical limit switch, but it does not omit the origin return operation (origin mark detection operation) of the machining head.

[0010] In addition, an example of a well-known INC type linear encoder is disclosed in Patent Document 2. The device of Patent Document 2 is configured to detect the origin position of a scale by an origin pattern (10) and a light receiving unit (52), and various improvements have been implemented.

[0011] In a coordinate measuring machine, the time required for the probe movable body to return to the origin when the power is turned on also depends on the position of the probe movable body when the power is turned on. When starting the operation from the position farthest from the origin mark, it takes about 1 minute for a medium-sized device and even about 3 minutes for a large device.

[0012] Even if the return-to-origin operation is performed once a day, it is inefficient. If an unexpected error occurs after the measurement preparation is completed and the power is turned on again, the inefficiency time doubles. For example, if the power is turned on again 5 times a day, 5 minutes are wasted for a medium-sized device and 15 minutes are wasted for a large device. If it is done 10 times a day, 10 minutes are wasted for a medium-sized device and 30 minutes are wasted for a large device.

[0013] Furthermore, if the operation procedure is determined to be such that the power of the coordinate measuring machine is turned off each time a workpiece is loaded or unloaded for safety reasons, the power is turned on again dozens of times a day, which significantly reduces the measurement efficiency.

[0014] Prior art literature

[0015] Patent Literature

[0016] Patent Document 1: Japanese Patent Application Publication No. 2009-220119

[0017] Patent Document 2: Japanese Patent Application Publication No. 2017-116306 Summary of the invention

[0018] Problem that the invention aims to solve

[0019] There is a thought that if an ABS scale is used instead of an INC scale to read the absolute position information of the probe moving body in real time, it will save the time of the origin return operation in the INC scale. This is because the INC scale counts the movement amount from the origin position obtained by the origin return to obtain the relative position information of the probe moving body, while the ABS scale does not require the origin position and can obtain the absolute position information at any position by simply reading the scale at that position. However, the application of the ABS scale to the coordinate measuring machine has the following problems.

[0020] Among coordinate measuring machines, there is a type of coordinate measuring machine that measures the surface shape of a workpiece by sequentially reading the moving position of the probe moving body from a scale while driving and controlling the probe moving body so that a scanning probe scans along the surface of the workpiece. In this case, a control device of the coordinate measuring machine sequentially acquires probe signals from the moving probe and uses the probe signals as triggers to read each position information of the probe moving body.

[0021] An ABS type linear encoder is usually constructed such that an ABS detector that reads the absolute position information of the scale is connected to an encoder interface (hereinafter referred to as encoder I / F) via a serial communication line, and the ABS detector outputs the absolute position information in response to a request signal sent by the encoder I / F.

[0022] When an ABS type linear encoder is applied to a coordinate measuring machine, the absolute position information of the probe movable body is obtained as follows. First, the control device of the coordinate measuring machine receives a probe signal from the probe. Next, a request signal is sent to the ABS detector. The ABS detector outputs the absolute position information at the time point when the request signal is received to the control device. The request signal and the signal of the absolute position information as its response are sent and received between the control device and the ABS detector. The following situation occurs: due to a time lag between the timing when the control device of the coordinate measuring machine receives the probe signal and the timing when the ABS detector sends the absolute position information, the absolute position information (true value) when the probe signal is received cannot be obtained. In this structure, the control device obtains position information delayed by at least one sampling time.

[0023] Acquiring position information delayed by one sampling time means adding a time error to the measured value, which is a problem in the function of a coordinate measuring machine that "acquires position coordinates while moving a probe to measure length."

[0024] An object of the present invention is to provide a coordinate measuring machine and a coordinate measuring program capable of shortening the time from power-on until measurement preparation is completed without impairing a high-precision measurement function.

[0025] Solutions for solving problems

[0026] The inventors focused on the advantages of using an ABS scale to omit the return operation of the mechanical origin and the advantages of using an INC scale to obtain position information in real time. Furthermore, they developed a coordinate measuring machine that is configured to perform a preset using an ABS scale when the power is turned on and read the high-precision position information obtained by the INC scale when the workpiece shape is measured later, and completed the present invention. As a specific example, an "ABS-INC scale" is installed in the coordinate measuring machine, and a "unit that performs a preset of an incremental counter (hereinafter referred to as an INC counter) using an absolute position signal from an ABS detector when the power is turned on" and a "unit that reads the count value of the INC counter using a probe signal as a trigger when the workpiece shape is measured" are used. As a result, it was found that the return operation of the probe moving body to the mechanical origin when the power is turned on can be eliminated, and a high workpiece shape measurement accuracy using a scanning probe can be maintained.

[0027] That is, the coordinate measuring machine (10) according to the present invention comprises:

[0028] A workpiece support body (12) for supporting the workpiece;

[0029] a probe moving body (20) which moves the probe (30) relative to the workpiece; and

[0030] a control device (50) for driving and controlling the probe movable body and acquiring position information of the probe movable body at the detection timing when the probe detects the workpiece,

[0031] wherein the coordinate measuring machine (10) measures the shape of the workpiece based on the position information,

[0032] The coordinate measuring machine (10) further comprises:

[0033] an incremental pattern (42) arranged along the moving direction of the probe movable body; an absolute pattern (43) arranged along the moving direction of the probe movable body; an incremental detector (45) which detects the incremental pattern and outputs a waveform signal having a quantity proportional to the moving amount of the probe movable body; and an absolute detector (46) which detects the absolute pattern at a receiving timing of a request signal from the control device and outputs an absolute position signal of the probe movable body,

[0034] The control device (50) comprises:

[0035] an incremental counting unit (51) for counting the waveform signal from the incremental detector;

[0036] a position information acquisition unit (52) that reads the count value of the incremental counting unit at the detection timing of the workpiece detected by the probe; and

[0037] A preset unit (54) sends a request signal to the absolute detector for presetting the incremental counting unit, obtains the absolute position signal from the absolute detector, and presets the absolute position signal to the incremental counting unit.

[0038] According to this structure, the control device of the coordinate measuring machine operates as follows. First, when the power is turned on, the "presetting unit" performs the preset of the INC counting unit using the absolute position information from the ABS detector. Therefore, the origin return operation of the probe moving body during the preset is not required, thereby greatly shortening the preparation time from the power being turned on until the measurement preparation is completed. Next, in the workpiece shape measurement, the "INC counting unit" counts the number of waveform signals corresponding to the movement amount of the probe moving body based on the preset value, so that the "position information acquisition unit" can immediately read the count value of the INC counting unit at the timing of receiving the probe signal, and output the count value as the position information of the probe moving body. Therefore, the position information (true value) at the time of receiving the probe signal can be obtained, so that no time error is generated when acquiring the position information of the probe.

[0039] However, it is costly to set two scales, the ABS scale and the INC scale, along the moving direction of the probe moving body. Therefore, in the coordinate measuring machine involved in the present invention, it is preferable that the incremental pattern and the absolute pattern are formed on one scale. In this way, if the two scales, ABS and INC, are formed in the same scale, only one scale is required, so the cost increase can be suppressed to a minimum. In the present invention, this composite scale is called an ABS-INC scale.

[0040] In the coordinate measuring machine according to the present invention, it is preferred that the control device includes a servo lock unit that performs servo lock control on a servo motor that is a drive motor for the probe movable body, and the servo lock unit is configured to servo lock (= maintain a predetermined rotation angle) the servo motor to stop the rotation during the preset operation of the preset unit. In this structure, when the INC counting unit is preset, the probe movable body is brought into a state of being reliably stopped by the servo lock, thereby improving the reliability of the preset operation.

[0041] A computer-readable storage medium according to the present invention stores a coordinate measuring program for measuring a shape of a workpiece by acquiring position information of a probe moving body at a detection timing when the workpiece is detected by a probe, and causing a computer to execute the following processing:

[0042] Incremental counting processing, for obtaining a waveform signal of a number proportional to the movement amount of the probe moving body from the incremental detector, and counting the waveform signal;

[0043] a position information acquisition process for reading a count value of the incremental counting process at a detection timing at which the workpiece is detected by the probe; and

[0044] The preset process is used to send a request signal to the absolute detector for performing the preset in the incremental counting process, obtain the absolute position signal of the probe movable body from the absolute detector, and preset the absolute position signal to the incremental counting process.

[0045] According to the configuration of the computer-readable storage medium, in addition to the above-mentioned effects, it is possible to automate workpiece shape measurement by computer, perform remote operation via a wired or wireless network, and the like.

[0046] Effects of the Invention

[0047] According to the structure of the present invention, by utilizing the structure of the ABS type scale, the origin return operation of the probe moving body that has been required so far can be discarded when the INC counting unit is preset, and when using a scanning probe for measurement, the structure of the INC type scale can be utilized to maintain high-precision measurement of the workpiece shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a block diagram showing the overall configuration of the coordinate measuring machine according to the first embodiment.

[0049] Figure 2 It is a block diagram showing the overall configuration of a coordinate measuring machine according to a second embodiment.

[0050] Figure 3 This is a timing chart of coordinate measurement performed using the coordinate measuring machine of the above-described embodiment.

[0051] Description of Reference Numerals

[0052] 10: coordinate measuring machine; 12: platform (workpiece support body); 20: probe moving body; 30: probe; 41: ABS-INC scale (scale); 42: incremental pattern (INC pattern); 43: absolute pattern (ABS pattern); 45: incremental detector (INC detector); 46: absolute detector (ABS detector); 50: control device; 51: incremental counting unit (INC counting unit); 52: position information acquisition unit; 53: workpiece shape information generation unit; 54: preset unit; 55: servo locking unit; 60: encoder I / F; 61: counting unit; 62: latch unit (position information acquisition unit); 63: request unit (preset unit); 64: preset unit (preset unit); 70: main computing device; 71: measurement trigger unit; 72: workpiece shape information generation unit; 73: preset trigger unit; 74: servo locking unit (servo locking unit); 110: coordinate measuring machine. DETAILED DESCRIPTION

[0053] Figure 1 1 is a block diagram showing a configuration example of a coordinate measuring machine according to a first embodiment of the present invention. The coordinate measuring machine 10 includes: a workpiece placement platform 12; a portal-type probe moving body 20 that can slide in the Y direction on the platform 12; a probe 30 that is supported by the probe moving body 20; a position detection device 40 that detects the position of the probe moving body 20 in the Y direction; and a control device 50.

[0054] The probe moving body 20 is composed of a gate-shaped Y slide 22, an X slide 24 that can slide along the horizontal arm of the Y slide 22, and a Z probe rod 26 that is supported by the X slide 24 so as to be lifted and lowered. Although not shown in the figure, the movement of these slides and probe rods is performed by a well-known driving unit. In this embodiment, a servo motor is used as the driving unit. In addition, a position detection unit 40 for detecting the position of the slide and the probe rod in the moving direction is provided in each direction. Here, the position detection unit 40 in the Y direction is described in detail as a representative.

[0055] Figure 1The coordinate measuring machine 10 composed of the platform 12 and the portal-type probe movable body 20 is only an example, and the workpiece support body and the probe movable body can be any structure as long as they are configured to move the probe 30 at least relative to the workpiece (W). For example, a movable table capable of moving the workpiece in the Y direction may be used as the workpiece support body, and the Y direction of the probe movable body may be fixed.

[0056] The probe 30 is mounted on the lower end of the Z probe bar 26 and has a built-in sensor. When the probe 30 contacts the workpiece or detects the workpiece in a non-contact manner, the probe 30 outputs a signal indicating that the workpiece has been detected. This signal is referred to as a probe signal.

[0057] The position detection device 40 has a long ABS-INC scale 41 and a detection head 44. The ABS-INC scale 41 is fixed to the side of the platform 12 along the moving direction of the Y slide 22. The detection head 44 is installed below the driving side column of the Y slide 22 in such a way that the detection surface faces the pattern surface of the ABS-INC scale 41, and moves integrally with the Y slide 22.

[0058] On the surface of the scale 41, a pattern surface including two INC patterns 42 and an ABS pattern 43 is formed along the long direction of the scale 41. On the detection surface of the detection head 44, the INC detector 45 and the ABS detector 46 are arranged in such a manner that the INC detector 45 faces the INC pattern 42 of the scale 41 and the ABS detector 46 faces the ABS pattern 43 of the scale 41. According to the positional relationship between the scale 41 and the detection head 44, when the probe moving body 20 moves in the Y direction, the INC detector 45 detects the INC pattern 42 of the portion corresponding to its moving position, and the ABS detector 46 detects a portion of the ABS pattern 43 in the same manner.

[0059] The INC pattern 42 may be composed of, for example, a plurality of rectangular patterns arranged at a fixed pitch. In this case, when the INC detector 45 passes through a rectangular pattern as the probe movable body 20 moves, a waveform signal (e.g., a pulse signal) is output. Therefore, the INC detector 45 outputs a plurality of waveform signals proportional to the amount of movement of the probe movable body 20, and transmits them to the control device 50 as analog or digital signals. As for the waveform signal output by the INC detector 45, a signal that can be output continuously or a signal that can be counted by a counting unit such as a counter is appropriate.

[0060] The ABS pattern 43 can be constituted by a pattern that depends on the relative position of the scale and the detection head, such as a pattern of data including M-sequence symbols. In this case, when the ABS detector 46 detects a part of the ABS pattern 43, information such as the number information assigned to the long axis direction of the ABS pattern 43 is read, absolute position information that varies according to the moving position of the detection head 44 is output, and is transmitted as a digital signal to the control device 50.

[0061] The control device 50 is constituted by Figure 1 various functional blocks such as the INC counting unit 51, position information acquisition unit 52, workpiece shape information generation unit 53, preset unit 54, and servo lock unit 55 shown.

[0062] In addition, the control device 50 is configured to be able to receive a signal indicating that the power is turned on from the outside, perform two-way communication (such as serial communication) with the ABS detector 46, receive a waveform signal from the INC detector 45, and receive a probe signal.

[0063] <INC counting unit>

[0064] The function of the INC counting unit 51 is to sequentially count the waveform signal sent unidirectionally from the INC detector 45.

[0065] <Position information acquisition unit>

[0066] The function of the position information acquisition unit 52 is to read the count value of the INC counting unit 51 at the reception timing of the probe signal, and output this count value as the current position information of the probe moving body 20. Here, it is configured to output immediately after reading the count value at the reception timing of the probe signal, but for example, the position information acquisition unit 52 can also be configured to temporarily store the count value in a storage unit and output the count value in the storage unit together with acquisition time information and the like later.

[0067] <Workpiece shape information generation unit>

[0068] The function of the workpiece shape information generation unit 53 is to generate the trajectory of the probe 30, that is, the workpiece shape information, based on the current position information from the position information acquisition unit 52.

[0069] <Preset unit>

[0070] The function of the preset unit 54 is to receive a preset execution instruction caused by power-on and send a request signal to the ABS detector 46, and is to obtain an absolute position signal from the ABS detector 46 and preset this absolute position signal to the INC counting unit 51. The preset unit 54 is configured to be connected to the ABS detector 46 in a serial communication manner and operate in the form of requests and responses.

[0071] <Servo lock unit>

[0072] The function of the servo lock unit 55 is to perform servo lock control on the servo motor for driving the probe movable body 20. The servo lock unit 55 functions as follows: the servo motor is servo-locked (controlled to maintain the servo motor at a predetermined rotation angle) during the preset operation of the preset unit 54, thereby stopping the rotation of the motor. By providing the servo lock unit 55, when the INC counting unit 51 is preset, the probe movable body 20 is reliably stopped by the servo lock, thereby improving the reliability of the preset operation.

[0073] The control device 50 configured as described above can execute a preset operation including the following steps at the stop position of the probe movable body 20 when the power is turned on, without causing the probe movable body 20 to move at all.

[0074] (1) A signal of a preset execution command (preset trigger) caused by power-on is input to the preset unit 54 and the servo lock unit 55. In response to the signal, the servo lock unit 55 issues a command signal for electrically servo-locking the servo motor of the probe movable body 20. Then, after confirming that the rotation angle of the servo motor is maintained at a predetermined angle, a signal indicating the servo lock state is output to the preset unit 54.

[0075] (2) The preset unit 54 transmits a request signal to the ABS detector 46 when receiving the preset execution instruction signal and the servo lock state signal.

[0076] (3) The ABS detector 46 outputs the absolute position signal read from the ABS pattern 42 upon receiving the request signal.

[0077] (4) The preset unit 54 presets the count value of the INC count unit 51 to the value of the absolute position signal based on the received absolute position signal.

[0078] (5) The preset unit 54 outputs a preset completion signal to the servo lock unit 55. The servo lock unit 54 issues a command signal to release the servo lock of the servo motor. The preset operation is completed through the above steps, and the measurement preparation is completed.

[0079] Furthermore, the control device 50 executes a workpiece shape measuring operation including the following steps.

[0080] (6) After the preset operation is completed, the INC counting unit 51 counts the waveform signal from the INC detector 45 based on the preset count value. For example, the count is added when the Y slide 22 moves forward, and the count is subtracted when the Y slide 22 moves backward.

[0081] (7) When receiving the probe signal, the position information acquiring unit 52 immediately reads the count value of the INC counting unit 51 and outputs the count value to the workpiece shape information generating unit 53 .

[0082] (8) The workpiece shape information generating unit 53 acquires a large number of count values ​​from the position information acquiring unit 52, that is, the current position information of the probe movable body 20 at the timing of receiving the probe signal, generates workpiece shape information based on the current position information, stores the workpiece shape information in the storage unit, displays it on the display unit as needed, and outputs it to the outside.

[0083] Furthermore, the control device 50 may be constituted by a device including a computer. In this case, the computer performs the coordinate measurement program including steps (1) to (8), respectively. Figure 1 Functions of the functional blocks shown in the figure. If the coordinate measurement program is used, it becomes easy to automate the workpiece shape measurement by computer, to perform remote operation via a wired or wireless network, and the like.

[0084] Figure 2 1 is a block diagram showing a configuration example of a coordinate measuring machine according to a second embodiment of the present invention. Here, the control device 50 of the first embodiment is divided into an encoder I / F 60 and a main computing device 70. The configurations related to the configurations of the first embodiment are marked with the same Figure 1 The markup is the same as the markup.

[0085] exist Figure 2 In the coordinate measuring machine 110, the encoder I / F (encoder interface) 60 can be formed by combining the encoder I / F of the INC type scale and the encoder I / F of the ABS type scale. In this case, the ABS type scale performs the preset of the counter, and the INC type scale performs the acquisition of the current position information of the probe movable body 20.

[0086] like Figure 2 As shown in FIG. 1 , the encoder I / F 60 is composed of various functional blocks such as a counting unit 61, a latch unit 62, a request unit 63, and a preset unit 64. The encoder I / F 60 may be composed of a device including a computer. In this case, the coordinate measurement program for the encoder I / F 60 is executed by the computer, thereby respectively exerting the functions of the functional blocks included in the encoder I / F 60.

[0087] The main computing device (host computer) 70 is composed of various functional blocks such as a measurement trigger unit 71, a workpiece shape information generating unit 72, a preset trigger unit 73, and a servo lock unit 74, and the functions of these functional blocks are respectively exerted by executing a coordinate measurement program for the main computing device 70. The main computing device 70 is configured to control the drive of the coordinate measuring machine 110 and to perform necessary data processing.

[0088] use Figure 2 and Figure 3 The preset operation in this embodiment is described. Figure 3 This is a sequence diagram of a coordinate measurement program consisting of a process from power-on until measurement preparation is completed and a process when the workpiece shape is measured.

[0089] (1) When the power of the coordinate measuring device 110 is turned on, a power-on signal is input to the main computing device 70. When the servo lock unit 74 of the main computing device 70 confirms the power-on signal, it issues a command signal (S1) for electrically servo-locking the servo motor of the probe movable body 20. In addition, after confirming the servo lock, a servo lock signal indicating the servo lock state is output to the preset trigger unit 73 (S2).

[0090] (2) When receiving the power-on signal and the servo lock signal, the preset trigger unit 73 outputs a preset trigger signal to the encoder I / F 60 ( S3 ).

[0091] (3) When the request unit 63 of the encoder I / F 60 confirms the preset trigger signal, it transmits a request signal to the ABS detector 46 (S4).

[0092] (4) Upon receiving the request signal, the ABS detector 46 reads the absolute position signal from the ABS pattern 42 and transmits the absolute position signal to the encoder I / F 60 (responds) (S5).

[0093] (5) The preset unit 64 of the encoder I / F 60 presets the count value of the counter unit 61 to the value of the absolute position signal based on the received absolute position signal (S6). The request unit 63 and the preset unit 64 are components of the preset means of the present invention.

[0094] (6) The preset section 64 outputs a preset completion signal to the servo lock section 74 of the main computing device 70 (S7). The servo lock section 74 issues a servo lock release command signal (S8). The preset operation is completed through the above steps, and the measurement preparation is completed.

[0095] Next, the workpiece shape measuring operation will be described.

[0096] (7) After the preset operation is completed, the counting unit 61 of the encoder I / F 60 counts the waveform signal from the INC detector 45 based on the preset count value (S11).

[0097] (8) When the workpiece shape measurement starts and the stylus 30 detects the workpiece, the stylus signal is input to the main computing device 70. When the measurement trigger unit 71 of the main computing device 70 confirms the stylus signal, it outputs the measurement trigger signal to the encoder I / F 60 (S12).

[0098] (9) When the latch unit 62 of the encoder I / F 60 confirms the measurement trigger signal, it immediately holds the count value of the counter unit 61 (S13) and outputs the held count value to the main computing device 70 (S14). The latch unit 62 is a component of the position information acquisition unit of the present invention. The operations of step S12 to step S14 are repeated.

[0099] (10) The workpiece shape information generating unit 72 of the main computing device 70 acquires a large amount of count values ​​from the encoder I / F 60, that is, current position information of the probe movable body 20 at the timing of receiving the probe signal, and generates workpiece shape information based on the current position information (S15).

[0100] As described above, according to the coordinate measuring machines 10 and 110 of the respective embodiments, when the power is turned on, the motor is first servo-locked, and the coordinate value of the absolute position of the probe movable body 20 is acquired by using the structure of the ABS type scale. Then, the acquired coordinate value is preset in the structure of the INC type scale, and the subsequent workpiece shape measurement is performed by using the preset structure of the INC type scale.

[0101] As a result, the mechanical origin return operation of the probe moving body 20 originally required in the structure of the INC type scale can be abandoned, and the problem of deviation from the true value such as the time error added to the measured value in the structure of the ABS type scale (serial communication) is also eliminated. In other words, the time from power on to completion of measurement preparation is shortened, and the measurement time and downtime are shortened, and efficient measurement can be performed without deteriorating the accuracy of workpiece shape measurement, thereby maintaining high-precision workpiece shape measurement.

[0102] Furthermore, in Patent Document 1, in the measurement preparation stage, after confirming the approximate position using the ABS type scale, it is necessary to move the head to the origin position of the INC type scale and determine the coordinate value at the origin position. In contrast, in the coordinate measuring machines 10 and 110 of each embodiment, the accurate position is detected by the ABS type scale, and after the detection, the coordinate value can be determined at the position without moving the probe movable body 20.

[0103] In addition, in the coordinate measuring machines 10 and 110 of each embodiment, the ABS-INC scale 41 is used. Since two patterns 42 and 43, ABS and INC, are formed on the same scale 41, only one scale 41 can be provided in the position detection device 40 in one direction, and the cost increase can be suppressed to the minimum. Furthermore, even if one pattern (scale) is damaged, if the other pattern is normal, the workpiece shape measurement can be continued without stopping the operation of the coordinate measuring machine 10 and 110.

[0104] In the above description, the position detection of the Y slide 22 (equivalent to the Y-direction probe moving body) is exemplified, but the same structure can also be applied to the position detection of the X slide 24 (equivalent to the X-direction probe moving body) and the Z probe rod (equivalent to the Z-direction probe moving body). In this case, the workpiece shape information generating unit 53 and the workpiece shape information generating unit 72 can read the current position information of the probe 30 from the scale of each axis, and based on the read position information of each axis, the three-dimensional shape information of the workpiece can be measured efficiently and accurately.

Claims

1. A coordinate measuring machine comprising: A workpiece support body, which supports the workpiece; A probe moving body, which moves the probe relative to the workpiece; as well as a control device for driving and controlling the probe movable body, sequentially acquiring probe signals transmitted from the probe during scanning of the workpiece surface, and acquiring each position information of the probe movable body at the timing of acquiring the probe signals, in, The coordinate measuring machine measures the shape of the workpiece based on the position information, The coordinate measuring machine is characterized by further comprising: an incremental pattern arranged along the moving direction of the probe moving body; an absolute pattern arranged along the moving direction of the probe moving body; an incremental detector that detects the incremental pattern and outputs a waveform signal whose quantity is proportional to the movement amount of the probe movable body; as well as an absolute detector that detects the absolute pattern and outputs an absolute position signal of the probe moving body, The control device comprises: an incremental counting unit, which sequentially counts the waveform signal from the incremental detector; a position information acquisition unit that sequentially reads count values ​​of the incremental counting unit at the timing of acquisition of the probe signal of the probe; and A preset unit sends a request signal to the absolute detector for presetting the incremental counting unit, obtains the absolute position signal from the absolute detector, and presets the absolute position signal to the incremental counting unit.

2. The coordinate measuring machine according to claim 1, characterized in that The incremental pattern and the absolute pattern are formed on one scale.

3. The coordinate measuring machine according to claim 1 or 2, characterized in that: The control device includes a servo lock unit that performs servo lock control on a servo motor that is a drive motor for the probe movable body. The servo lock unit is configured to servo-lock the servo motor to stop the rotation during the preset operation of the preset unit.

4. A computer-readable storage medium storing a coordinate measurement program for measuring a workpiece shape by sequentially acquiring probe signals sent from a probe scanning a workpiece surface and acquiring position information of a probe moving body at a timing of acquiring the probe signals, wherein the computer-readable storage medium is characterized in that: The coordinate measuring program causes the computer to execute the following processing: Incremental counting processing, for obtaining a number of waveform signals proportional to the amount of movement of the probe moving body from the incremental detector, and sequentially counting the waveform signals; Position information acquisition processing for sequentially reading count values ​​of the incremental counting processing at the timing of acquisition of the probe signal of the probe; as well as The preset process is used to send a request signal to the absolute detector for performing the preset in the incremental counting process, obtain the absolute position signal of the probe movable body from the absolute detector, and preset the absolute position signal to the incremental counting process.

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