JP2009080616A - Numerical control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a numerical control device for correctly measuring a machine position during a test operation by using a measuring unit for measuring a machine position, obtaining a machine error from the measurement result, and correctly obtaining a parameter for correcting the machine error. <P>SOLUTION: This numerical control device for controlling the relative position of a main axis with respect to a table of a machine by driving a motor so that a detected position to be output from a detector 4 detecting the position of a motor 3 may follow a commanded position is provided with: a measuring unit 5 for machine position measurement for measuring the displacement of the relative position of a main axis to the table of a machine in a prescribed direction; a machine position calculating part 6 for calculating the machine position based on the detected position output from the detector 4 and the detected position output from the measuring unit 5 for machine position measurement and a signal for machine position measurement at the same time; a machine error difference measurement part 7 for calculating a machine error based on the commanded position, the detected position output from the detector 4 and the machine position calculated by the machine position calculation part 6; and a parameter changing part 8 for changing the parameter for error correction based on the machine error. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a numerical control apparatus for numerically controlling (NC) a machine tool, and more particularly to a numerical control apparatus for accurately obtaining a machine position by attaching a position detector such as a double ball bar to a machine end.

  Numerically controlled machine tools perform machining by controlling each axis to the commanded position, but the points to be measured using a position detector to control the position and the points to be controlled, that is, the actual machining is performed. It is different from what you do. Hereinafter, the position of a point measured using a position detector is referred to as a “detection position”, and the position of a point where machining is actually performed is referred to as a “machine position”.

  For example, when semi-closed control is performed with a ball screw drive machine, the measurement point is the rotation angle of the motor, but the point to be controlled is a moving body attached to the tip of the ball screw.

  Even when full-closed control is performed using a linear scale, the linear scale cannot be placed at the actual processing point, so the detection position (the position where the linear scale is attached) and the machine position (the actual processing point) Is far from.

  For this reason, even if the numerical control device controls the detected position so as to follow the commanded position, generally, the machine position does not completely follow the commanded position, and the final machining shape does not match the commanded value. In another example, in a 5-axis processing machine having a rotation axis or a machine having a parallel mechanism mechanism, if there is a design error in a mechanism parameter such as the position of the rotation axis, each axis is instructed from the commanded position (from the commanded shape, Even if it is controlled to the position calculated using the design value of the mechanism parameter, the final machining shape does not match the command shape.

  Therefore, the machine error (difference between the detection position and the machine position) when the test operation is performed in advance is measured, and the numerical control device corrects only the error, or the mechanism parameter according to the error. There are ways to fix this. In order to measure the error of the machine, in addition to the position detector used in the numerical control device, a measuring instrument for measuring the machine position is used. This measuring instrument for measuring the machine position is not normally attached to the machine because it is difficult to perform the original operation of the machine tool such as machining if it is attached to the machine. (For example, refer patent document 1).

Japanese Patent Laid-Open No. 2004-1203

  Conventionally, since the measurement of the machine position is performed independently of the command position and the detection position, it is impossible to accurately grasp the moment-to-time relationship between the machine position and the detection position. Therefore, although a geometric error can be measured, a dynamic error (for example, an error between a moving machine position and a detection position) cannot be measured. In particular, when the machine position is measured using a device that measures the distance between two points such as a so-called double ball bar, the double ball bar measures a one-dimensional displacement. It is not possible to accurately determine the position within. Conventionally, the command shape and the command speed are known, and the machine position in the three-dimensional space is determined from the measured distance between two points, that is, the one-dimensional displacement, assuming that the machine is also moving at the commanded shape and speed. However, since the actual movement is accompanied by acceleration and deceleration, there is a problem that the conventional method cannot correctly determine the machine position. Furthermore, since the measurement operation of the machine position is conventionally performed independently of the position control for the test operation, the measurement result is confirmed at each measurement, and if the measurement is not performed correctly, it is necessary to repeat the measurement. There was a problem that it was necessary.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to attach a measuring instrument to obtain the machine position and set the machine position during the test operation to the same time axis as the command position and the detection position. A numerical control apparatus is obtained that can measure the above, obtain a machine error from the measurement result, and accurately obtain a parameter for correcting the obtained machine error.

  The numerical controller according to the present invention controls the relative position of the spindle to the machine table by driving the motor so that the detected position output from the detector follows the command position by detecting the position of the motor. In the numerical controller, a mechanical position measuring instrument that measures a displacement in a predetermined direction of a relative position of the spindle relative to the table of the machine, a detection position output from the detector, and an output from the mechanical position measuring instrument Calculated by a machine position calculation unit that calculates a machine position based on a machine position measurement signal at the same time as the detection position, the command position, the detection position output from the detector, and the machine position calculation unit. A machine error calculation unit that calculates a machine error based on the machine position and a parameter change unit that changes a parameter for error correction based on the machine error are provided. It is intended.

  The numerical control device according to the present invention has an effect that the machine position at the same time as the command position and the detection position can be accurately obtained. In addition, since the machine error is determined based on the command position, detection position, and machine position at the same time and the parameter for correcting the machine error is changed, the machine error correction parameter can be set accurately. Play.

Embodiment 1 FIG.
A numerical control apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a numerical control apparatus according to Embodiment 1 of the present invention. In the following, in each figure, the same reference numerals indicate the same or corresponding parts.

  In FIG. 1, a numerical controller according to Embodiment 1 of the present invention includes a command generation unit 1 that generates a command position, a mechanical drive unit 2 that drives a motor 3, and a detector 4 that detects the position of the motor 3. A mechanical position measuring instrument 5 that measures the displacement of the spindle relative to the machine table in a predetermined direction; a machine position calculator 6 that calculates the machine position; and a machine error in the detected position and the machine position. There are provided a machine error calculation unit 7 for performing the above and a parameter changing unit 8 for changing a parameter for error correction based on the machine error.

  FIG. 2 is a perspective view showing the setup of the measuring instrument for measuring the machine position of the numerical controller according to Embodiment 1 of the present invention.

  In FIG. 2, the double ball bar used as the machine position measuring instrument 5 has a structure in which two balls 52 and 53 are connected by a linear motion shaft 51, and outputs a distance between the two balls 52 and 53. It is a length sensor that can. One of the two spheres 52 is fixed to the machine table 90 by a magnet 54, and the other sphere 53 is fixed to a main spindle 91 of the machine by a magnet 55. In the machine, it is assumed that the main shaft 91 moves with respect to the table 90 in each of three orthogonal directions (X axis, Y axis, Z axis). The path (broken line) 80 of the test operation is a circular orbit centered on the sphere 52 on the table 90 side, and the spindle 91 is positioned so that the centers of the two spheres 52 and 53 of the double ball bar are always in the plane of the circular orbit. Shall move.

  Next, the operation of the numerical control apparatus according to the first embodiment will be described with reference to the drawings.

  The command generation unit 1 generates and outputs a command position of the relative position of the spindle with respect to the table of the machine every moment for driving the machine. The command generation unit 1 generates a command position for each drive shaft of the machine at a constant cycle based on the test operation path 80. Further, when generating the command position, the command generation unit 1 refers to the parameter for correcting the mechanical error of the parameter change unit 8 and corrects the command position so that the mechanical error is eliminated. The command position generated by the command generator 1 is input to the machine drive unit 2.

  The mechanical drive unit 2 drives the motor 3. The mechanical drive unit 2 controls the motor 3 so that the detection position output from the detector 4 attached to the motor 3 follows the command position. The position of the motor 3 is detected by the detector 4 and input to the mechanical drive unit 2 as a detection position. Note that the command drive unit 2 may correct the command position instead of the command generation unit 1 so that the machine error is eliminated by referring to the parameter for correcting the machine error of the parameter changing unit 8.

  The machine position measuring instrument 5 is a sensor that is separately installed in the machine to measure the machine position, and uses a sensor that outputs a displacement having a dimension smaller than the number of dimensions of the machine position. In the first embodiment, a double ball bar which is a kind of length sensor is used. The double ball bar 5 is not attached during normal machine operation, but is temporarily attached only when the machine is adjusted. The double ball bar 5 measures the distance between the two balls 52 and 53 during the test operation and outputs a length signal (one-dimensional displacement signal). The output length signal is input to the machine position calculation unit 6. In the first embodiment, since a double ball bar is used as the machine position measuring instrument 5, the machine position measuring signal is a length signal of the double ball bar.

  The detection position output from the machine drive unit 2 is input to the machine position calculation unit 6 at the same time as the machine position measurement signal output from the machine position measurement measuring instrument 5. That is, the detection position and the length signal measured by the double ball bar 5 are input to the machine position calculation unit 6, and these detection position and length signals are input at the same time.

  The machine position calculation unit 6 calculates the machine position based on the input detection position and the machine position measurement signal (length signal), and outputs the machine position to the machine error calculation unit 7. The machine position is on a straight line connecting the center position of the command arc that is the path 80 of the test operation and the detection position, and the distance from the center of the command arc is the value of the length signal measured by the double ball bar 5. The coordinates are obtained as the machine position.

This can be expressed as follows: Suppose that the command arc that is the path 80 of the test operation is an arc in the XY plane, the length at time t measured by the double ball bar 5 is l (t), and the time t when the center of the command arc is the origin. (X _d (t), y _d (t), z _d (t)) is the machine position (x _m (t), y _m (t), z _m (t) at the same time t. ) Is obtained by the following equation (1).

  The machine error calculation unit 7 calculates a machine error from the machine position obtained by the machine position calculation unit 6, the command position, and the detection position. For example, the difference between the detected position and the machine position before and after the change direction of the command position is reversed is obtained. That is, the mechanical error calculation unit 7 calculates a motion error when the driving direction of the motor 3 is reversed. If there is backlash or lost motion in the machine element, the difference between the detected position and the machine position is almost opposite in value before and after the direction of the command position is changed.

  The parameter changing unit 8 changes the parameters of the machine error correction function according to the machine error obtained by the machine error calculating unit 7. For example, since the parameter has a function of correcting the command position when reversing the machine direction as a function for correcting the backlash, the parameter is set so that the difference between the detected position and the machine position becomes the correction amount. That is, the parameter changing unit 8 changes a parameter for correcting the command position when the driving direction is reversed based on the motion error described above.

  In the past, measurement was performed with a single double ball bar, and when calculating the machine position from the length signal of the double ball bar, the calculation was made assuming that the machine was moving at a constant speed on the circular arc path. However, since acceleration and deceleration occur in practice at the start and end, the machine position obtained by the conventional method is greatly different from the actual machine position.

  On the other hand, in the first embodiment, since the machine position is obtained from the length signal at the same time and the detection position, the displacement signal having a dimension smaller than the number of dimensions of the machine position output from the machine position measuring instrument is used. The correct machine position can be determined. That is, the three-dimensional machine position can be correctly obtained from the one-dimensional length signal output from the double ball bar.

  Furthermore, in the conventional method, since the time relationship between the change in the command position and the change in the machine position is unknown, the behavior of the machine position when the command direction is reversed cannot be obtained accurately, and the parameter for machine error correction is It cannot be determined accurately.

  On the other hand, in the first embodiment, since the command position and the machine position at the same time can be known, the behavior of the machine position when the command direction is reversed can be accurately obtained, and the parameters for correcting the machine error can be accurately determined. It can be obtained.

  As described above, according to the first embodiment, since the machine position is obtained from the length signal of the machine position measuring instrument 5 at the same time as the command position and the detection position, there is acceleration and deceleration during movement. There is an effect that an accurate machine position can be obtained. Further, according to the first embodiment, since the machine error is obtained based on the machine position at the same time as the command position and the detection position and the parameter of the machine error correction function is changed, the machine error correction parameter is accurately set. There is an effect that it can be set. In particular, in the first embodiment, since the motion error at the time of driving direction reversal can be accurately grasped including the timing, parameters for correcting mechanical errors generated at the time of reversing the driving direction such as backlash and lost motion can be accurately determined. There is an effect that it can be set.

Embodiment 2. FIG.
A numerical controller according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 3 is a block diagram showing a configuration of a numerical control apparatus according to Embodiment 2 of the present invention.

  In FIG. 3, the difference from the first embodiment is that a machine position display unit 9 is further provided. The machine position display unit 9 outputs a command position output from the command generation unit 1 and a machine drive unit 2 outputs the command position. And the machine position output by the machine position calculation unit 6 are displayed.

  FIG. 4 is a perspective view showing the setup of the measuring instrument for measuring the machine position of the numerical controller according to Embodiment 2 of the present invention.

  In FIG. 4, the difference from the first embodiment is that the radius of the path 80 for the test operation is shorter than the length between the two spheres 52 and 53 of the double ball bar. Such a setup is effective when it is desired to measure the machine position at the time of the circular arc command when the movable range of the machine is narrow and the machine cannot be operated along the path as in the first embodiment.

  Next, the operation of the numerical control apparatus according to the second embodiment will be described with reference to the drawings. FIG. 5 is a diagram showing a display example of the machine position display unit of the numerical controller according to Embodiment 2 of the present invention.

  The difference from the first embodiment described above is the calculation operation of the machine position in the machine position calculation unit 6 and the display operation in the machine position display unit 9.

  The machine position calculation unit 6 obtains a machine position from the input detection position and length signal. The machine position is on a straight line connecting the center position of the command arc and the detection position, and the point where the distance from the center of the sphere 52 on the table 90 side becomes the value of the length signal measured by the double ball bar 5 is the machine position. As its coordinates.

This can be expressed as follows: Suppose that the command arc is an arc in the XY plane, the length at time t measured by the double ball bar 5 is l (t), and the detection position at time t when the center of the sphere 52 on the table 90 side is the origin is the position. (X _d (t), y _d (t), z _d (t)), the machine position (x _m (t), y _m (t), z _m (t)) at the same time t is It is calculated | required like Formula (2).

  The machine position display unit 9 displays the command position, the detection position, and the machine position on the screen display of the numerical controller. By displaying these positions on the same coordinate axis, it is possible to visually grasp the relative relationship between the command position, detection position, and machine position. You can quickly check how it changes. FIG. 5 is an example of the screen display content.

  As described above, according to the second embodiment, an accurate machine position can be obtained even when the movable range of the machine is narrow and the machine cannot be operated along the route as in the first embodiment. There is an effect that can be done. Further, according to the second embodiment, the measured command position, detection position, and machine position are displayed on the same coordinate system on the screen, so that the relative relationship between the command position, detection position, and machine position is visually determined. Thus, there is an effect that it is possible to quickly confirm how the locus changes by changing the parameter of the mechanical error correction function.

Embodiment 3 FIG.
A numerical control apparatus according to Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 6 is a block diagram showing a configuration of a numerical control apparatus according to Embodiment 3 of the present invention.

  In FIG. 6, the difference from the second embodiment is that a measurement abnormality detection unit 10 and a command change unit 11 are further provided. In addition, when the measurement abnormality detection unit 10 determines that the machine position measurement signal output from the machine position measurement instrument 5 deviates from the measurable range of the machine position measurement instrument 5, the measurement abnormality detection unit 10 outputs the abnormality signal. When the command change unit 11 receives an abnormal signal, the command change unit 11 changes the operation command so that the machine position measurement signal does not deviate from the measurable range. That is, the operation command is output to the command generation unit 1, and when the operation command is changed, the measurement is performed again based on the changed operation command.

  FIG. 7 is a perspective view showing the setup of the measuring instrument for measuring the machine position of the numerical controller according to Embodiment 3 of the present invention.

  In FIG. 7, the difference from the first embodiment is that the main shaft 91 of the machine has a rotation axis that rotates around the rotation center axis 82 in addition to the translational movement axes in the three orthogonal directions. It is that. At this time, one point on the rotation center axis 82 is set as a pivot point 83. The mechanical drive unit 2 drives the translational movement axis of the pivot point 83 and the rotation axis around the pivot point 83. Further, the path 80 of the test operation is centered on the sphere 52 on the table 90 side of the double ball bar 5, and has a circular arc on a plane perpendicular to the rotation center axis 82. The route should be suitable. That is, the position of the pivot point 83 is a path obtained by adding a deviation amount between the pivot point 83 and the sphere 53 on the spindle 91 side to the test operation path 80 (pivot point path 81 during the test operation). .

  When the position of the tip end of the main shaft 91 is commanded in a machine having such a rotating shaft, the amount of movement of the translation shaft is converted from the amount of movement of the tip of the main shaft 91 to the amount of movement of the pivot point 83, and the translation shaft is moved. Need to drive. Therefore, in the command generation unit 1, the relative position between the tip of the main shaft 91 and the pivot point 83 (a point on the rotation center axis) when the rotation axis is at a certain angle (for example, 0 degree) is determined as the rotation center position. It is stored as a parameter, and the amount of movement of the tip of the main shaft 91 is converted into the amount of movement of the pivot point 83 based on this rotation center position parameter and the rotation axis angle command position at that time.

  Next, the operation of the numerical control apparatus according to the third embodiment will be described with reference to the drawings.

  The difference from the first embodiment is that the machine position calculation unit 6 performs a machine position calculation operation, the machine error calculation unit 7 performs a machine error calculation operation, and the parameter change unit 8 performs a parameter change operation. And the operation of the measurement abnormality detection unit 10 and the command change unit 11.

  The machine position calculation unit 6 obtains a machine position from the input detection position and length signal. The machine position is on a straight line connecting the center position of the command arc and the detection position, and the point where the distance from the center of the sphere 52 on the table 90 side becomes the value of the length signal measured by the double ball bar 5 is the machine position. As its coordinates.

This can be expressed as follows: If the command arc is an arc in the XZ plane, the length at time t measured with the double ball bar 5 is l (t), and the detected position of the rotation axis is θ _d (t), the machine position at the same time t (X _m (t), y _m (t), z _m (t)) is obtained as in the following equation (3).

However, when θ _d = 0, it is assumed that the main shaft 91 faces the negative direction of the Z axis. Also, here, the feed rate is sufficiently slow, and the detection position of the rotation axis and the detection position of the three orthogonal axes are sufficiently synchronized, and the direction of the detection position viewed from the center position of the command arc and the direction of the main shaft 91 are The mathematical formula is derived as a match.

  The machine error calculation unit 7 calculates an error between the parameter of the rotation center position (the displacement amount of the sphere 53 on the pivot point 83 side and the spindle 91 side) and the actual measurement value from the machine position and the detection position. A value obtained by correcting the error obtained by the mechanical error calculation unit 7 is set in the parameter for storing the rotation center position.

  The measurement abnormality detection unit 10 monitors whether the length signal output from the double ball bar 5 does not deviate from the measurable range, and outputs an abnormality signal when deviating. When the abnormality signal is output from the measurement abnormality detection unit 10, the command change unit 11 stops the measurement, returns the drive axes of the machine to the start position of the test operation path 80, and then changes the operation path. And measure again. When the length signal exceeds the upper limit of the measurable range, the radius of the operation path is reduced. The amount to be reduced is a value that does not exceed the difference between the minimum value of the length signal from the start of measurement to the stop of measurement and the lower limit value of the measurable range. When the length signal falls below the lower limit value of the measurable range, the radius of the operation path is increased. The amount to be increased is a value that does not exceed the difference between the upper limit of the measurable range and the maximum value of the length signal from the start of measurement to the stop of measurement.

  As described above, according to the third embodiment, there is an effect that an accurate machine position can be obtained even in a complicated operation path including movement of the rotating shaft. Further, according to the third embodiment, since the rotation center position of the rotation axis is obtained based on the machine position at the same time as the command position and the detection position, and the rotation center position parameter is set, There is an effect that the position parameter can be set accurately. Furthermore, according to the third embodiment, when the length signal output from the double ball bar 5 deviates from the measurable range, the measurement is stopped, the operation path condition is changed, and the measurement is performed again. There is an effect that the measurement can be surely performed without causing the machine position measuring instrument 5 to fail.

  In the third embodiment, the example in which the main shaft side rotates has been described, but the table side may rotate.

Embodiment 4 FIG.
A numerical control apparatus according to Embodiment 4 of the present invention will be described with reference to FIGS. FIG. 8 is a block diagram showing a configuration of a numerical control apparatus according to Embodiment 4 of the present invention.

  In FIG. 8, the difference from the first embodiment is that a two-dimensional coordinate measuring device (grid encoder) is used instead of the double ball bar as the mechanical position measuring measuring device 5A. This two-dimensional coordinate measuring device (grid encoder) can also be applied to the second embodiment and the third embodiment.

FIG. 9 is a perspective view showing the state of setup of the measuring instrument for measuring the machine position of the numerical controller according to Embodiment 4 of the present invention.

  In FIG. 9, the grid encoder used as the machine position measuring instrument 5 </ b> A has a scanning head 56 placed on a plate 57 having a fine grid (grid), and the scanning head 56 in a plane parallel to the surface of the plate 57. A two-dimensional displacement signal is output. The plate 57 of the grid encoder 5A is installed on the machine table 90, and the scanning head 56 of the grid encoder 5A is attached to the spindle 91. It is assumed that the test operation path 80 moves the scanning head 56 in a straight line parallel to the surface of the plate 57.

  Next, the operation of the numerical control apparatus according to the fourth embodiment will be described with reference to the drawings.

  The difference from the first embodiment described above is that the output of the machine position measuring instrument 5A is not a length signal but a two-dimensional displacement signal in a two-dimensional plane, a machine position calculation unit 6, and a machine error calculation. The operations of the unit 7 and the parameter changing unit 8 are as follows.

  In the following description, it is assumed that the surface of the plate 57 of the grid encoder 5A is attached in parallel to the XY plane, and the test operation path 80 moves at a constant speed in the X-axis direction.

Machine position measuring instrument 5A outputs the X-direction displacement _x g (t) at time t, Y-axis direction displacement _y g a (t).

The machine position calculation unit 6 calculates the machine position during the test operation. If the detection position at time t when the start position of the test operation is the origin is (x _d (t), y _d (t), z _d (t)), the machine position (x _m (t ), Y _m (t), z _m (t)) are obtained by the following equation (4).

Here, x _m0 and y _m0 in the equation (4) are detection positions at the start position of the test operation.

The machine error calculation unit 7 obtains a difference between the detection position and the machine position during the test operation. The section of the test operation is divided into n points, when the x-coordinate of the divided k-th point and x _k, the difference [Delta] x k of the machine position and the detected position when the detection position is x _k, determining a [Delta] y _k . Δx _k is an X-axis pitch error, and Δy _k is a Y-axis straightness error. That is, the machine error calculation unit 7 calculates the pitch error and the straightness error of the detection position and the machine position at points specified in advance during the movement of the main spindle 91 of the machine.

  The parameter changing unit 8 changes parameters for pitch error correction and straightness error correction based on the pitch error and straightness error obtained by the mechanical error calculation unit 7. That is, the parameter changing unit 8 changes the parameter for correcting the command position of the point specified based on the pitch error and the straightness error.

  As described above, according to the fourth embodiment, since the machine position at the same time as the detected position is known, there is an effect that the machine error during movement can be accurately obtained. Further, according to the fourth embodiment, since the pitch error and the straightness error at the point specified in one movement command can be obtained simultaneously, the correction parameters for the pitch error and the straightness error can be set accurately and quickly. There is an effect that it can be set.

  In the fourth embodiment, the example in which the measurement direction of the machine position measuring instrument 5A and the direction of the machine drive shaft coincide with each other has been described, but these may be different. In that case, the machine position calculation unit 6 performs coordinate conversion based on the measurement value of the machine position measurement measuring instrument 5A when moved in the machine drive axis direction to obtain the machine position in the machine drive axis direction. Good.

  Further, in each of the above embodiments, the example in which the table 90 is fixed and the main shaft 91 moves is used for the translational movement axis. Conversely, the main shaft 91 is fixed and the table 90 moves. Alternatively, a certain axis (for example, the X axis and the Z axis) may be such that the main axis 91 moves, and another axis (for example, the Y axis) may move the table 90. In either case, the position of the main shaft 91 may be replaced with the relative position of the main shaft 91 with respect to the table 90.

It is a block diagram which shows the structure of the numerical control apparatus which concerns on Embodiment 1 of this invention. It is a perspective view which shows the mode of a setup of the measuring device for machine position measurement of the numerical control apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the numerical control apparatus which concerns on Embodiment 2 of this invention. It is a perspective view which shows the mode of a setup of the measuring device for machine position measurement of the numerical control apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the example of a display of the machine position display part of the numerical control apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the numerical control apparatus which concerns on Embodiment 3 of this invention. It is a perspective view which shows the mode of a setup of the measuring device for machine position measurement of the numerical control apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the numerical control apparatus which concerns on Embodiment 4 of this invention. It is a perspective view which shows the mode of a setup of the measuring device for machine position measurement of the numerical control apparatus which concerns on Embodiment 4 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Command generation part, 2 Machine drive part, 3 Motor, 4 Detector, 5 Machine position measuring instrument (double ball bar), 5A Machine position measuring instrument (grid encoder), 6 Machine position calculation part, 7 Machine Error calculation unit, 8 parameter change unit, 9 machine position display unit, 10 measurement abnormality detection unit, 11 command change unit.

Claims (8)

In a numerical control device that drives the motor to control the relative position of the spindle to the table of the machine so that the detection position output from the detector follows the command position by detecting the position of the motor.
A machine position measuring instrument for measuring a displacement in a predetermined direction of the relative position of the spindle relative to the table of the machine;
A machine position calculation unit that calculates a machine position based on a detection position output from the detector and a machine position measurement signal output from the machine position measurement measuring instrument at the same time as the detection position;
A machine error calculator that calculates a machine error based on the command position, a detection position output from the detector, and a machine position calculated by the machine position calculator;
A numerical control device comprising: a parameter changing unit that changes a parameter for error correction based on the mechanical error. The machine position measuring instrument is a length sensor, and the machine position measuring signal is a length signal indicating a distance between one point on the machine table and one point on the spindle,
The machine position calculation unit calculates a machine position based on a detection position output from the detector and a length signal output from the length sensor and at the same time as the detection position. The numerical controller described. The mechanical error calculation unit calculates a motion error when the motor driving direction is reversed,
The numerical control device according to claim 1, wherein the parameter changing unit changes a parameter for correcting a command position when the driving direction is reversed based on the motion error. The machine error calculation unit calculates the error of the rotation center position of the spindle of the machine or the rotation axis of the table,
The numerical controller according to claim 1, wherein the parameter changing unit changes a parameter of the rotation center position based on an error of the rotation center position. The machine position measuring instrument is a two-dimensional coordinate measuring instrument, and the machine position measuring signal is a two-dimensional displacement indicating a displacement in a two-dimensional plane between a point on the machine table and a point on the spindle. Signal,
The machine position calculation unit calculates a machine position based on a detection position output from the detector and a two-dimensional displacement signal output from the two-dimensional coordinate measuring device and at the same time as the detection position. The numerical controller according to claim 1. The machine error calculation unit calculates a pitch error and a straightness error of the point based on the detection position and the machine position at a point specified in advance during the movement of the spindle of the machine,
The numerical controller according to claim 1, wherein the parameter changing unit changes a parameter for correcting a command position of a point specified based on the pitch error and the straightness error. A measurement abnormality detection unit that determines an abnormality when the machine position measurement signal output from the machine position measurement instrument deviates from the measurable range;
A command changing unit that stops measurement when the measurement abnormality detecting unit determines that an abnormality has occurred, and changes an operation command so that the machine position measurement signal does not deviate from the measurable range;
The numerical control device according to any one of claims 1 to 6, wherein when the operation command is changed, measurement is performed again based on the changed operation command. The machine position display unit for displaying the command position, the detection position output from the detector, and the machine position calculated by the machine position calculation unit on the same coordinate system. The numerical control device according to claim 7.

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