JP2006112861A - Three-dimensions coordinate measuring system and part program used for same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive configuration capable of highly accurate measurements by making the effects of hysteresis uniform regardless of the last direction of measurement. <P>SOLUTION: In this three-dimensional measuring system for computing measurement element parameters on the basis of three-dimensional positional information on a probe when the probe is in contact with an object to be measured, the measurement element parameters are computed by continuously bringing the probe into contact with a point of measurement of the object to be measured twice from the same direction and capturing only three-dimensional positional information when the probe is in contact at the second time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a three-dimensional coordinate measurement system that measures a three-dimensional coordinate value of a measurement location by bringing a probe into contact with the measurement location using a part program, and a part program used therefor.

  In a three-dimensional coordinate measuring machine using a contact detection type probe, the probe stylus tip is brought into contact with one or a plurality of measurement points of a workpiece to be measured, and the trigger tip is generated by capturing the moment, thereby generating a probe tip. The surface properties (parameters of measurement elements) such as positions, dimensions, and geometric shapes of each part of the workpiece are measured and calculated based on the acquired three-dimensional coordinate values.

  In such a probe that generates a trigger signal by contacting the measurement target position, a structure in which the stylus is not restrained with respect to the housing that supports the probe and the workpiece is employed in order to prevent damage to the probe and the workpiece at the time of contact. Yes.

  FIG. 7 is a diagram showing an example of a probe employing such a structure. In this probe 100, a stylus 101 is supported on a housing 102 by a six-point contact type seating mechanism. That is, a seating body 103 is fixed to the base end portion of the stylus 101, and the seating body 103 forms an angle of 120 ° with respect to the center axis in a plane perpendicular to the center axis of the stylus 101. Three cylindrical pins 104 extending radially are projected. These pins 104 are placed on a V-shaped locking portion 105 provided on the housing 102 side so as to correspond to each pin 104. The seating body 103 is pressed by a spring 106 that urges each pin 104 in a direction in which the pin 104 is pressed against the V-shaped locking portion 105. The seating body 103, the pin 104, the V-shaped locking portion 105, and the spring 106 constitute a six-point contact type seating mechanism. In addition, a probe having a configuration in which a stylus is swingably held by a holder via a pin is also known.

  In such a conventional probe, if the stylus returns to the neutral position in principle when it comes out of the measurement target position after coming into contact with the measurement target position, it is actually a six-point contact in the seating mechanism. Due to the friction of the part, a receipt error occurs in which the coordinates of the stylus tip (center position of the contact sphere) do not return to the neutral position. This value is on the order of sub-microns, but cannot be ignored in high-precision measurements. Therefore, a probe having a mechanism for mechanically correcting such a receipt error by forcibly displacing the six-point contact portion of the seating mechanism with a piezoelectric element or the like has been proposed (Patent Document 1). , 2).

Further, it is known that the receipt error is affected by the direction of contact with the object to be measured immediately before, that is, the hysteresis. Therefore, in the pinching measurement in which the contact direction changes by 180 °, the influence of this hysteresis is maximized. Therefore, the relationship between the previous contact direction between the probe and the measurement target and the current contact direction and the correction amount is tabulated in advance, and at the actual measurement, the current probe contact direction and the previous probe contact direction There is also known a three-dimensional measurement system in which a correction amount is obtained from a correction table and a measurement value is corrected by the obtained correction amount (Patent Document 3).
Japanese Patent Laid-Open No. 10-96618, paragraphs 0021 to 0023, FIGS. 5 to 7 JP 2001-4356 A, paragraphs 0031-0034, FIG. Japanese Patent Laid-Open No. 2003-50118, paragraphs 0024, 0029 to 0031, FIGS. 1 and 3

  In the probes disclosed in Patent Documents 1 and 2 described above, it is necessary to provide a displacement generating mechanism such as a piezoelectric element in each probe. Further, the three-dimensional coordinate measurement system disclosed in Patent Document 3 determines a correction value based on a combination of a contact direction to the measurement target position to be measured at present and a contact direction to the immediately previous measurement target position. Therefore, the correction value cannot be determined unless the previous contact direction is known. There is also a problem that the number of combinations of preliminary measurements for creating a correction table is enormous and it takes a long time for preliminary measurements.

  The present invention has been made in view of the above points, and has a low-cost configuration and is not affected by the immediately preceding measurement direction, and reduces the influence of hysteresis and enables high-accuracy measurement and The purpose is to provide a part program used for this.

  A three-dimensional coordinate measuring system according to the present invention includes a three-dimensional coordinate measuring machine that outputs information on a three-dimensional coordinate position of the probe when the probe contacts the object to be measured, and a relative drive of the probe based on a part program. A control means for controlling and calculating a parameter of a measurement element from the output information of the three-dimensional coordinate position of the probe, wherein the control means is configured to measure the probe with the measurement target of the object to be measured. The position is continuously contacted from the same direction a plurality of times, and the parameters of the measurement element are calculated by taking in the information of the three-dimensional coordinate position when the probe contacts the second time or later. To do.

  The part program of the three-dimensional coordinate measuring machine according to the present invention provides the probe of the three-dimensional coordinate measuring machine that outputs information on the three-dimensional coordinate position of the probe when the probe contacts the measured object. It includes a measurement command for processing the information of the three-dimensional coordinate position when the measurement target position is continuously contacted a plurality of times from the same direction, and the probe contacts the second and subsequent times.

  Here, the relative movement control of the probe refers to the movement control of either or both of the probe and the object to be measured.

  Further, the parameter of the measurement element means each parameter of the surface property such as the position, dimension or geometric shape of each part of the workpiece.

  According to the three-dimensional coordinate measurement system according to the present invention, the control means causes the probe to contact the measurement target position of the object to be measured continuously a plurality of times from the same direction, and among these, the probe is contacted for the second and subsequent times. Since the parameter of the measurement element is calculated by taking in the information of the three-dimensional coordinate position, the contact direction immediately before the measurement is always known, so that the influence of hysteresis is reduced and high-precision measurement is possible.

  Further, according to the part program of the three-dimensional coordinate measurement system according to the present invention, the probe of the three-dimensional coordinate measuring machine that outputs information of the three-dimensional coordinate position of the probe when the probe contacts the object to be measured is measured. It includes a measurement command for processing (for example, storing) the information of the three-dimensional coordinate position when the probe is continuously contacted multiple times from the same direction, and the probe contacts the second and subsequent times. This eliminates the need to create similar measurements by combining complex commands, and can reduce the burden of part program creation work.

  Hereinafter, a three-dimensional coordinate measurement system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a schematic configuration of this system.

  The three-dimensional coordinate measuring system includes a three-dimensional coordinate measuring machine 1, a drive control device 2 for driving and controlling the three-dimensional coordinate measuring machine 1 and taking in necessary measurement coordinate values from the three-dimensional coordinate measuring machine 1. The J / S operation panel 3 for manually operating the three-dimensional coordinate measuring machine 1 through the drive control device 2 and a part program for instructing the measurement procedure in the drive control device 2 are edited and executed, and the drive control is performed. The host system 4 includes a function for performing calculations for applying a geometric shape to the measurement coordinate values acquired via the apparatus 2 and recording and transmitting a part program.

  The three-dimensional coordinate measuring machine 1 is configured as follows. That is, the surface plate 11 is placed on the vibration isolation table 10 so as to coincide with the horizontal surface with the upper surface as a base surface, and the arm supports 12 a and 12 b erected from both side ends of the surface plate 11. The X-axis guide 13 is supported at the upper end. The lower end of the arm support 12a is driven in the Y-axis direction by the Y-axis drive mechanism 14, and the lower end of the arm support 12b is supported on the surface plate 11 by the air bearing so as to be movable in the Y-axis direction. . The X-axis guide 13 drives a Z-axis guide 15 extending in the vertical direction in the X-axis direction. The Z-axis guide 15 is provided so that the Z-axis arm 16 is driven along the Z-axis guide 15, and a contact type probe 17 is attached to the lower end of the Z-axis arm 16. When the probe 17 comes into contact with the workpiece 5 placed on the surface plate 11, a touch signal is output from the probe 17 to the drive control device 2, and the drive control device 2 takes in the XYZ axis coordinate values at that time. It has become.

  FIG. 2 is a block diagram of this three-dimensional coordinate measurement system. The three-dimensional coordinate measuring machine 1 includes an XYZ axis motor 18 for driving the probe 17 in the XYZ axis direction, and an XYZ axis encoder 19 for outputting a movement pulse in each axis direction in accordance with the movement in the XYZ axis direction. Has been. The operation panel 3 includes a joystick 31 as manual operation means for manually driving the probe 17 of the three-dimensional coordinate measuring machine 1 in the XYZ axis directions, and the XYZ axis coordinate values of the current position of the probe 17 on the controller 2. A coordinate value input switch 32 is provided for inputting to.

  The controller 2 is provided with a CPU 21, which performs drive control of the probe 17, measurement coordinate value capture control, correction of the measurement coordinate value, and the like. That is, the XYZ axis drive control unit 22 drives the XYZ axis motor 18 of the three-dimensional coordinate measuring machine 1 according to the command of the CPU 21, and the XYZ axis counter 23 counts the pulse signal corresponding to each axis from the XYZ axis encoder 19. The current position coordinate value is obtained and fed back to the CPU 21. The current position coordinate values are sequentially stored in the current position register 24. The CPU 21 performs drive control of the probe 17 based on this feedback information. The CPU 21 stops the XYZ axis motor 18 in response to the touch signal from the probe 17 and takes in the current position coordinate value stored in the current position register 24.

  From the operation panel 3, the voltage value of the potentiometer corresponding to each axis corresponding to the tilt direction and tilt angle of the joystick 31 is output, and the moving direction / speed determining unit 25 of the controller 2 responds to the voltage value of each axis. The moving direction and moving speed of the probe 17 are determined. In the correction table 26, information on a receipt error (a correction value based on a displacement from the neutral position of the probe after contact and separation) with respect to each movement direction when the probe is in contact with 17 is stored as a correction value. . The CPU 21 uses the coordinate information acquired from the current position register 24 in response to the touch signal and the correction value obtained by referring to the correction table 26 from the moving direction of the probe 17 (measurement target parameters (each part of the work 5). The surface property parameters such as the position, size, or geometric shape of the image are calculated.

  The host system 4 includes a host computer 41, a monitor 42, a printer 43, a keyboard 44, a part program storage unit 45, and the like. The part program storage unit 45 stores a part program file for controlling the three-dimensional coordinate measuring machine 1 via the controller 2.

  Next, the operation of the three-dimensional coordinate measurement system configured as described above will be described.

  In the present invention, the correction table 26 is not essential, but when the correction table 26 is used, the correction table 26 is prepared prior to measurement. The correction table 26 is measured, for example, by bringing a reference sphere whose coordinate value is known in advance by the probe 17 into contact with each direction (for example, six directions of X, Y, Z, -X, -Y, and -Z) twice. Then, the correction table 26 is created based on the measurement error at that time.

  Next, in actual measurement, measurement processing is performed according to the part program.

  FIG. 3 is a diagram illustrating an example of a part program. The left side is an instruction (command) and the right side is an argument. “Circle Circle (1)” is a command for measuring a circle and storing the result in Circle (1). “Measurement point X = 20.000 Y = 0.000 Z = 0.000 Angle X = 0: 00: 00 Angle Y = 90: 00: 00 Angle Z = 90: 00: 00” is the first point measurement command. Indicates the measurement target position, and the latter half indicates the measurement direction. The following two commands are point measurement commands for the second and third points, respectively. “Element finished” is a command indicating the end of circle measurement, and is a command for calculating circle parameters from the first to third measurement results and storing them in Circle (1).

  In the present invention, a command for 2-touch measurement is newly used in addition to the measurement command as described above. FIG. 4 shows an example of a part program according to the present invention including commands for 2-touch measurement.

  Here, a command for two-touch measurement called “Measurement point h” is newly prepared, but the other arguments are the same as in the past.

  FIG. 5 is a flowchart showing processing of the CPU 21 when a command for 2-touch measurement is activated.

  First, from the current probe position toward the measurement target position (ex.X = 20.000 Y = 0.000 Z = 0.000), the specified direction (ex.Angle X = 0: 00: 00 Angle Y = 90: 00: The probe 17 is moved to (00 Angle Z = 90: 00: 00) (S1). The movement of the probe 17 is continued until the probe tip (contact ball) contacts the workpiece 5. When the probe tip contacts the workpiece 5 (S2), the probe 17 is returned again to the movement start position (S3), and the probe 17 is moved again in the designated direction toward the measurement target position (S4). Then, the XYZ axis coordinate values (measurement data) at the moment when the touch signal is output at the second contact (S5) of the probe tip are captured (S6).

  Since the measurement data acquired by the above two-touch measurement is the state of the probe 17 before the measurement data is acquired, that is, the hysteresis is known, the obtained measurement value may be subjected to a certain correction process, If necessary, the correction table 26 may be used to correct by the correction value specified by the moving direction of the probe 17.

  Thus, according to the present system, the probe 17 is brought into contact with the workpiece 5 twice from the same direction, and the coordinate value obtained at the end is taken in. Therefore, the influence of hysteresis can be reduced, Extremely accurate measurement is possible.

  According to the present system, as shown in FIG. 4, by newly preparing a command for 2-touch measurement, the burden of creating a part program can be reduced.

  In other words, if the above-described two-touch measurement is to be executed only with the previous command, as shown in FIG. 6, the same measurement target position is measured twice, based on a total of six measurement instructions and the measurement result of each second point. An instruction to calculate the circle parameter and store it in the variable Circle (1) is required, which makes the part program extremely complicated.

  In this regard, according to the present invention, two-touch measurement can be realized with almost no change from the conventional part program.

  In the three-dimensional coordinate measurement system according to the present embodiment, the two-touch measurement has been described, but the present invention is not limited to this.

  That is, instead of the 2-touch measurement, the measurement may be performed by continuously contacting a plurality of times such as 3-touch or 4-touch in the same direction. In this case, for example, in the 3-touch measurement, the processing may be performed by taking in the information of the 3D coordinate position of the 2nd touch or the 3rd touch, or the information of the 3D coordinate position of the 2nd touch and the 3rd touch may be obtained. Processing may be performed after taking in and averaging both.

  In addition, in FIG. 2, the correction table 26 shows an example of storing and correcting a correction value for a resending error in the same direction that does not include hysteresis. May be stored and corrected, and a directional correction value and a measurement speed correction value that are not caused by a receipt error may be stored and corrected.

  That is, the correction value of the receipt error caused by hysteresis is a history of the direction of the contact direction when the previous measurement target position is measured by two touches and the direction of the contact direction when the current measurement target position is measured by two touches. This is a correction value that corrects the receipt error that occurs based on this, and the receipt error due to this hysteresis is greatly reduced by the present invention. May be performed.

  In addition, the directionality correction value that does not result from a receipt error is a correction value that corrects a directionality error related to the sphericity of the contact ball at the tip of the probe or the stiffness of the stylus. Is a correction value determined independently.

  Further, the measurement speed correction value is a correction value resulting from the contact speed, and is a correction value determined independently of the receipt error.

  Furthermore, in the present embodiment, an example in which a 2-touch measurement command is used for a part program has been described. More specifically, when a two-touch measurement switch is provided on the operation panel 3 and the probe is positioned near the measurement target position, the two-touch measurement switch is set to “ON” and the joystick 32 is tilted toward the measurement target position. Two-touch measurement may be automatically performed.

It is a perspective view which shows the structure of the three-dimensional coordinate measuring system which concerns on one Embodiment of this invention. It is a block diagram of the same three-dimensional coordinate measurement system. It is a figure which shows an example of a part program. It is a figure which shows an example of the part program which instruct | indicates 2-touch measurement. It is a flowchart which shows the process of a 2 touch measurement command. It is a figure which shows an example of the part program for the 2-touch measurement created with the conventional measurement command. It is a figure which shows the probe used with the same three-dimensional coordinate measuring system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Three-dimensional coordinate measuring machine, 2 ... Controller, 3 ... Operation panel, 4 ... Host system.

Claims (4)

A three-dimensional coordinate measuring machine that outputs information of the three-dimensional coordinate position of the probe when the probe contacts the object to be measured;
A three-dimensional coordinate measurement system comprising: control means for performing relative drive control of the probe based on a part program and calculating a parameter of a measurement element from information of the three-dimensional coordinate position of the output probe;
The control means brings the probe into contact with the measurement target position of the object to be measured a plurality of times continuously from the same direction, and takes in the information of the three-dimensional coordinate position when the probe comes in contact for the second time and thereafter. A three-dimensional coordinate measurement system characterized by calculating a parameter of the measurement element.   The three-dimensional coordinate measurement system according to claim 1, wherein the part program includes a measurement command for bringing the measurement target position of the object to be measured into contact with the measurement target position a plurality of times from the same direction. A correction table that stores the relationship between the contact direction of the probe to the object to be measured and the displacement from the neutral position of the probe is provided.
The control means obtains a correction value based on the displacement from the neutral position of the probe by the correction table from the contact direction of the object to be measured to the measurement target position, and corrects the parameter of the measurement element. The three-dimensional coordinate measuring system according to claim 1 or 2, characterized in that:   The probe of the three-dimensional coordinate measuring machine that outputs information on the three-dimensional coordinate position of the probe when the probe comes into contact with the object to be measured is brought into contact with the measurement target position of the object to be measured continuously several times from the same direction A part program for controlling the three-dimensional coordinate measuring machine, including a measurement command for processing information on a three-dimensional coordinate position when the probe contacts the second time or later.

Images