WO2020208783A1 - Numerical control device - Google Patents

Numerical control device Download PDF

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Publication number
WO2020208783A1
WO2020208783A1 PCT/JP2019/015841 JP2019015841W WO2020208783A1 WO 2020208783 A1 WO2020208783 A1 WO 2020208783A1 JP 2019015841 W JP2019015841 W JP 2019015841W WO 2020208783 A1 WO2020208783 A1 WO 2020208783A1
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WIPO (PCT)
Prior art keywords
error
model
runout
processing unit
correction
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Application number
PCT/JP2019/015841
Other languages
French (fr)
Japanese (ja)
Inventor
泰一 石田
秀明 平光
Original Assignee
三菱電機株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by 三菱電機株式会社 filed Critical 三菱電機株式会社
Priority to CN201980095057.5A priority Critical patent/CN113711143A/en
Priority to JP2019555997A priority patent/JP6719684B1/en
Priority to PCT/JP2019/015841 priority patent/WO2020208783A1/en
Publication of WO2020208783A1 publication Critical patent/WO2020208783A1/en

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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/401—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/404—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia

Definitions

  • the present invention relates to a numerical control device that controls an industrial machine.
  • Some machine tools which are industrial machines, have a drive shaft such as a spindle, which is a mechanism for changing the rotation angle of the work or tool that is the object to be machined.
  • the numerical control device that controls such a machine tool controls the drive shaft.
  • the numerical control device may be referred to as an NC (Numerical Control) device.
  • Patent Document 1 discloses an NC device that controls a spindle of a machine tool.
  • the spindle may cause an error between the operation according to the command and the actual operation due to the structure of the spindle.
  • Such an error caused by the structure of the mechanism is called a mechanical error.
  • Mechanical errors that occur in the spindle include mechanical errors caused by runout, which is a phenomenon in which the position of the rotating shaft deviates from the original position.
  • the conventional NC apparatus disclosed in Patent Document 1 is required to correct mechanical errors due to runout with high accuracy.
  • the present invention has been made in view of the above, and an object of the present invention is to obtain a numerical control device capable of highly accurate correction of mechanical errors caused by a shift in the position of a rotating shaft.
  • the numerical control device controls a motor which is a drive source of a mechanism for rotating a tool or a work in a machine tool for machining a work using a tool.
  • the numerical control device has a temporary model setting unit and a mechanism for setting a temporary model of mechanical error due to center runout by obtaining a model function representing runout, which is a phenomenon in which the position of the rotation axis of the mechanism shifts.
  • a fitting processing unit that obtains an error model, which is a model of mechanical error, by fitting a model function to the measurement data that is the result of measuring the operation of, and a correction unit that corrects commands to the motor based on the error model. Be prepared.
  • the numerical control device has the effect of enabling highly accurate correction of mechanical errors caused by the displacement of the rotation axis.
  • the figure explaining the runout error and the periodic error in the spindle controlled by the NC apparatus shown in FIG. A block diagram showing a runout error processing unit included in the NC device shown in FIG.
  • the figure which shows the structure for detecting the rotation angle of the spindle controlled by the NC apparatus shown in FIG. The first figure explaining the runout error in the spindle controlled by the NC apparatus shown in FIG.
  • the figure which shows the example of the screen displayed on the display part of the NC apparatus shown in FIG. A block diagram showing a hardware configuration of an NC device according to a first embodiment of the present invention.
  • FIG. 1 is a diagram showing an NC device 1 according to a first embodiment of the present invention and a machine tool 2 controlled by the NC device 1.
  • the machine tool 2 processes the work 5 using a tool.
  • the machine tool 2 has a linear drive shaft 3 that changes the relative position between the work 5 and the tool by a linear motion, and a spindle 4 that changes the rotation angle of the tool or the work 5 by a rotary motion.
  • FIG. 1 shows a spindle 4 for rotating the work 5.
  • the main shaft 4 has a shaft 37 which is a rotation shaft. In FIG. 1, the illustration of the tool is omitted.
  • the linear drive shaft 3 is formed by the servomotor 32 that is the drive source of the linear drive shaft 3, the servo amplifier 31 that operates the servomotor 32, the ball screw 33 that is rotated by driving the servomotor 32, and the ball screw 33 that is rotated. It has a moving body 34 that moves in an axial direction parallel to the central axis of the ball screw 33.
  • the linear drive shaft 3 is a mechanism that converts the rotational motion of the ball screw 33 into a linear motion.
  • the servo amplifier 31 operates the servomotor 32 according to the axis command output from the NC device 1.
  • the NC device 1 controls the servomotor 32 by outputting an axis command to the servo amplifier 31.
  • the spindle 4 has a spindle motor 36 that is a drive source of the spindle 4 and a spindle amplifier 35 that operates the spindle motor 36.
  • the chuck 38 fixes the work 5 to the shaft 37, which is the output shaft of the spindle motor 36.
  • the spindle 4 is a mechanism for rotating the work 5 attached to the shaft 37.
  • the spindle amplifier 35 operates the spindle motor 36 according to the axis command output from the NC device 1.
  • the NC device 1 controls the spindle motor 36 by outputting an axis command to the spindle amplifier 35.
  • the NC device 1 includes a program acquisition unit 10 for acquiring a machining program, a program analysis unit 11 for analyzing the acquired machining program, and an axis command generation unit 12 for generating an axis command based on the analysis result by the program analysis unit 11. And have.
  • the axis command generation unit 12 generates an axis command for the linear drive shaft 3 and an axis command for the spindle 4.
  • the axis command generation unit 12 outputs the generated axis command to the adder 18 and the correction amount determination unit 16.
  • the NC device 1 includes a data acquisition unit 13 for acquiring measurement data of machine error, an input unit 14 for receiving an operation for inputting information, a data processing unit 15 for executing measurement data processing, and a display for displaying information. It has a part 20 and.
  • the data processing unit 15 has a runout error processing unit 21 that is responsible for data processing for runout error correction, and a periodic error processing unit 22 that is responsible for data processing for periodic error correction. The details of the runout error processing unit 21 and the periodic error processing unit 22 will be described later.
  • the mechanical error of the spindle 4 is measured by a measuring device.
  • the data acquisition unit 13 acquires measurement data which is a measurement result by the measuring device.
  • Information about the processing in the data processing unit 15 is input to the input unit 14 by the operation of the user of the NC device 1.
  • the data processing unit 15 executes data processing based on the measurement data fetched from the data acquisition unit 13 and the information input to the input unit 14.
  • the display unit 20 displays information related to processing in the data processing unit 15.
  • the data processing unit 15 outputs the error data that is the result of the data processing to the error data storage unit 17.
  • the error data storage unit 17 stores the error data.
  • the correction amount determination unit 16 determines the correction amount for correcting the mechanical error based on the error data read from the error data storage unit 17.
  • the correction amount determination unit 16 determines the correction amount, which is an angle for canceling the deviation from the commanded rotation angle of the spindle 4.
  • the correction amount determination unit 16 outputs the determined correction amount to the adder 18.
  • the adder 18 adds the determined correction amount to the value of the command angle with respect to the spindle 4.
  • the correction amount determining unit 16 and the adder 18 function as a correction unit for correcting a command to the spindle motor 36.
  • the adder 18 outputs an axis command after the correction amount has been added to the drive command unit 19.
  • the drive command unit 19 outputs a shaft command for the spindle 4 to the spindle amplifier 35. Note that the NC device 1 can correct the axis command to the spindle 4 even when the spindle 4 is a mechanism for rotating the tool, as in the case where the spindle 4 is a mechanism for rotating the work 5.
  • the NC device 1 also corrects the shaft command for the linear drive shaft 3 by the correction amount determining unit 16 and the adder 18.
  • the description of the correction of the axis command with respect to the linear drive shaft 3 will be omitted.
  • FIG. 2 is a diagram illustrating a runout error and a periodic error in the spindle 4 controlled by the NC device 1 shown in FIG.
  • the spindle 4 causes runout due to the uneven weight of the chuck 38, the work 5, or the tool.
  • Center runout is a phenomenon in which the position of the shaft 37 deviates from the original position. Due to the runout, the rotation center position of the shaft 37 shifts in the direction perpendicular to the center axis of the shaft 37.
  • the error due to the runout of the spindle 4 is a main component of the mechanical error generated in the spindle 4.
  • the above-mentioned measuring device divides the angle range of one rotation of the spindle 4 into a plurality of parts, and measures the error between the actual rotation angle of the shaft 37 and the command angle for each division point.
  • the NC device 1 corrects the command angle based on the error model obtained from the measurement data or the interpolation data obtained from the measurement data. In this way, the NC device 1 can reduce the mechanical error of the spindle 4 based on the measurement data of the error at each division point.
  • the NC device 1 corrects the runout error by correcting the command position or the command angle based on the measurement data of the error for each division point.
  • the period of the waveform representing the runout error shown in FIG. 2 is synchronized with the rotation period of the spindle 4.
  • the period of the runout error shown in FIG. 2 coincides with the rotation period of the spindle 4.
  • the mechanical error that occurs in the spindle 4 includes a runout error component and a periodic error component that is an error that occurs periodically.
  • the periodic error of the spindle 4 is caused by the position detector attached to the spindle motor 36.
  • the position detector detects the rotation angle of the spindle motor 36.
  • the spindle amplifier 35 drives the spindle motor 36 so that the value of the rotation angle detected by the position detector follows the commanded position. In FIG. 1, the position detector in the spindle motor 36 is not shown.
  • periodic error correction refers to defining an error model as an arbitrary waveform and defining an arbitrary period to periodically correct the error.
  • the periodic error has a characteristic of vibrating in a period shorter than the period of the runout error.
  • the NC device 1 corrects the mechanical error of the spindle 4 by using both the runout error correction, which is a correction for the runout error component, and the periodic error correction, which is a correction for the periodic error component.
  • the data acquisition unit 13 acquires measurement data of an error at each division point for the spindle 4.
  • the runout error processing unit 21 executes data processing for correcting the runout error based on the measurement data.
  • the error data storage unit 17 stores error data which is an error model or interpolated data obtained by data processing in the runout error processing unit 21. The details of the runout error processing unit 21 will be described later.
  • the data acquisition unit 13 acquires the measurement data of the periodic error generated in the spindle 4.
  • the periodic error processing unit 22 executes data processing for correcting the periodic error based on the measured data.
  • the periodic error processing unit 22 determines an arbitrary period based on the measurement data, and obtains error data for periodic correction.
  • the error data storage unit 17 stores the error data obtained by the data processing in the periodic error processing unit 22.
  • the correction amount determination unit 16 reads out the error amount corresponding to the command position in the axis command from the error data storage unit 17 for the runout error correction of the spindle 4 and the periodic error correction of the spindle 4.
  • the correction amount determination unit 16 obtains the value of the correction amount corresponding to the command position by sign-inverting the value of the read error amount.
  • the correction amount determination unit 16 determines the correction amount corresponding to the command position for the runout error correction and the periodic error correction.
  • the correction amount determination unit 16 obtains the sum of the correction amount for the runout error correction and the correction amount for the periodic error correction for the spindle 4, and outputs the obtained sum to the adder 18.
  • the NC device 1 sets the sum of the correction amount for the runout error correction and the correction amount for the periodic error correction as the correction amount for correcting the mechanical error, and the spindle 4 is set. Correct the axis command of.
  • FIG. 3 is a block diagram showing a runout error processing unit 21 included in the NC device 1 shown in FIG.
  • the runout error processing unit 21 has a tentative model setting unit 23 that sets a tentative model of the mechanical error by obtaining a model function representing a phenomenon that is a factor of the mechanical error that can occur in the mechanism.
  • the runout error processing unit 21 has a fitting processing unit 24 that obtains an error model that is a model of mechanical error by fitting a model function to the measurement data that is the result of measuring the operation of the mechanism.
  • the runout error processing unit 21 has an interpolation processing unit 25 that executes an interpolation processing of measurement data.
  • the NC device 1 sets a tentative model in consideration of the structure of the mechanism, and obtains an error model by fitting the model function of the tentative model to the measurement data.
  • the period of the model function is synchronized with the rotation period of the shaft 37.
  • the NC device 1 determines the correction amount for pitch error correction based on the error model.
  • the NC device 1 makes it possible to determine the correction amount by spline interpolation of the measurement data when the error model deviates from the actual error or when it is difficult to set the temporary model.
  • FIG. 4 is a diagram showing a configuration for detecting a rotation angle of the spindle 4 controlled by the NC device 1 shown in FIG.
  • FIG. 4 shows a shaft 37 and a position detector 40 of the spindle 4 shown in FIG.
  • the position detector 40 has a light emitting diode 41 which is a light emitting body, a fixed slit 42, and a photodiode 43 which is a light receiving body.
  • the photodiode 43 detects the light from the light emitting diode 41.
  • the fixed slit 42 is arranged between the light emitting diode 41 and the photodiode 43.
  • the fixed slit 42 is provided with an A-phase slit 45 and a B-phase slit 46, respectively, through which light can pass.
  • the photodiode 43 detects light that has passed through the A-phase slit 45 and light that has passed through the B-phase slit 46.
  • the photodiode 43 outputs an A-phase signal indicating a detection result of light passing through the A-phase slit 45 and a B-phase signal indicating a detection result of light passing through the B-phase slit 46.
  • a turntable 44 that rotates together with the shaft 37 is attached to the shaft 37.
  • the center of the turntable 44 coincides with the axis of the shaft 37.
  • the turntable 44 rotates about the shaft 37.
  • a plurality of teeth arranged at equal intervals are provided on the outer circumference of the turntable 44. The light from the light emitting diode 41 is blocked from entering the photodiode 43 by reaching the teeth, and enters the photodiode 43 when passing between the teeth.
  • the position detector 40 counts the number of teeth that have passed in front of both the A-phase slit 45 and the B-phase slit 46 based on the number of pulses of the A-phase signal and the number of pulses of the B-phase signal.
  • the position detector 40 detects the rotation angle of the shaft 37 based on the number of teeth counted.
  • the position detector 40 detects the rotation direction of the shaft 37 based on the phase difference between the A-phase signal and the B-phase signal.
  • FIG. 5 is a first diagram illustrating a runout error in the spindle 4 controlled by the NC device 1 shown in FIG.
  • FIG. 6 is a second diagram illustrating a runout error in the spindle 4 controlled by the NC device 1 shown in FIG. 5 and 6 show changes in the positional relationship between the position detector 40 and the turntable 44.
  • FIG. 5 shows the state of the turntable 44 when the runout does not occur, when one of the plurality of teeth 47 of the turntable 44 is detected by the position detector 40.
  • the point O is the center of the turntable 44 when runout does not occur.
  • FIG. 6 shows the turntable 44 when runout occurs.
  • the point C is the center of the turntable 44 when runout occurs.
  • the amount of movement of the rotating disk 44 due to the runout that is, the length between the points O and C is "d".
  • one tooth 48 different from the above-mentioned tooth 47 is detected by the position detector 40 among the plurality of teeth of the turntable 44.
  • the angle between the teeth 47 and the teeth 48 corresponds to an error E, which is a mechanical error of the spindle 4 due to the runout of the spindle motor 36.
  • FIG. 7 is a third diagram illustrating a runout error in the spindle 4 controlled by the NC device 1 shown in FIG.
  • the tentative model set in the tentative model setting unit 23 will be described by taking the modeling of the runout phenomenon shown in FIG. 6 as an example.
  • the X-axis which is the first axis
  • the Y-axis which is the second axis
  • the origin of the X-axis and the Y-axis is the point O.
  • FIG. 7 shows circles 51 and 52 in which the planar shape of the turntable 44 is simplified.
  • the circle 51 represents the turntable 44 when the runout does not occur.
  • the circle 52 represents the turntable 44 when runout occurs.
  • the radii of the circles 51 and 52 are "P", respectively.
  • the center point of the circle 51 coincides with the point O.
  • the amount of movement of the rotating disk 44 due to the runout is “d”.
  • the center point of the turntable 44 moves due to runout.
  • the point C which is the center of the circle 52, is the center point of the rotating disk 44 when runout occurs. It is assumed that the point C moves along the circle 53 due to the runout.
  • the circle 53 is a circle whose center is the point O and whose radius is “d”. It is assumed that the point C goes around the circle 53 once while the shaft 37 makes one rotation due to the phenomenon of center runout.
  • the circle 51 is represented by the following equation (1). Further, the circle 53 is represented by the following equation (2).
  • ⁇ COC' ⁇ , assuming that the line segment OC'and the line segment C'C are perpendicular to each other.
  • ⁇ is the angle formed by the line segment OC connecting the points C and O, which are the center points moved by the runout, and the X-axis.
  • the circle 52 is represented by the following equation (3).
  • the point A which is the intersection of the circle 52 and the Y-axis, represents the position of the tooth 48 shown in FIG.
  • the point B' which is the intersection of the extension line of the line segment C'C and the circle 52 at Y> 0, represents the position of the tooth 47 shown in FIG.
  • the length of the line segment AB is expressed by the following equation (4).
  • equation (4) "AB” represents the length of the line segment AB
  • O'C represents the length of the line segment O'C
  • OC' represents the length of the line segment OC'. ..
  • Equation (7) represents a model function for the mechanical error of the spindle 4 due to the runout of the spindle motor 36.
  • the temporary model setting unit 23 shown in FIG. 3 sets a model function as shown in the above equation (7) in the temporary model for the mechanical error due to the phenomenon of runout. In this way, the temporary model setting unit 23 can set the temporary model by simple modeling for the phenomenon of runout.
  • the temporary model setting unit 23 performs processing until the temporary model is set according to the input operation by the user.
  • the tentative model setting unit 23 generates a tentative model using the condition values input by the user.
  • the condition values are the above-mentioned "P" and "d” and the like.
  • the tentative model setting unit 23 may set the tentative model by acquiring a model function created by an external device of the NC device 1.
  • the temporary model setting unit 23 may make the locus of the point C due to the runout not only a circle but also an ellipse.
  • the temporary model setting unit 23 may be able to appropriately set the shape indicating the locus of the point C according to the characteristics of the spindle motor 36.
  • the fitting processing unit 24 performs fitting by the least squares method.
  • the above equation (7) is a multivariable function with " ⁇ ", " ⁇ " and "P'" as arguments.
  • the above equation (7) can be rewritten as the following equation (8).
  • M is an integer of 2 or more.
  • ⁇ i is a rotation angle according to the command, and is a rotation angle at the i-th point, which is one of the division points.
  • Z i is been an error measured in the i-th point.
  • the fitting processing unit 24 performs fitting by obtaining " ⁇ " and "P'" that minimize the function of "J” shown in the following equation (9).
  • the fitting processing unit 24 obtains a non-linear error model by the non-linear least squares method.
  • the Gauss-Newton method which is a typical nonlinear least squares method, can be used.
  • a method other than the Gauss-Newton method may be used.
  • the fitting processing unit 24 outputs the error model obtained by fitting to the error data storage unit 17.
  • the fitting processing unit 24 can also obtain an error model by fitting a polynomial of one variable to the measurement data instead of fitting to the above-mentioned tentative model.
  • the fitting processing unit 24 may obtain an error model close to the actual error by fitting with a polynomial.
  • Equation (10) is a polynomial with " ⁇ " as a variable.
  • Ck represents the coefficient of the k-th order term.
  • N is an integer of 2 or more.
  • K is a variable representing an integer from 0 to n.
  • the fitting processing unit 24 performs fitting by finding " kk " that minimizes the function of "J” shown in the following equation (11).
  • the fitting processing unit 24 can obtain “c k " by a known least squares method.
  • the value of "n”, which is the highest degree of the polynomial, is preset in the fitting processing unit 24.
  • the value of "n” may be set by an input operation by the user.
  • the NC device 1 can perform highly accurate correction of mechanical error by enabling selection between correction based on fitting by a tentative model and correction by fitting by a polynomial.
  • the fitting processing unit 24 may add a regularization term to the error model which is a polynomial.
  • the fitting processing unit 24 can obtain the following equation (12) by adding a regularization term to the above equation (11).
  • the fitting processing unit 24 performs fitting by finding " kk " that minimizes the function of "J” shown in the equation (12).
  • " ⁇ " is a regularization parameter.
  • the value of “ ⁇ ” is set in advance in the fitting processing unit 24.
  • the value of " ⁇ ” may be set by an input operation by the user. Overfitting, which can occur as the value of "n” increases, occurs when each coefficient of the polynomial becomes excessive.
  • the addition of the regularization term has the effect of preventing each coefficient from becoming excessive.
  • the fitting processing unit 24 can effectively suppress overfitting by adding a regularization term. As a result, the fitting processing unit 24 can obtain a highly versatile error model.
  • the degree of the polynomial used for spline interpolation is preset in the interpolation processing unit 25.
  • An arbitrary order can be set in the interpolation processing unit 25. The order may be set by an input operation by the user.
  • the interpolation processing unit 25 outputs the interpolation data obtained by spline interpolation to the error data storage unit 17.
  • the NC device 1 corrects the pitch error by spline interpolation of the measurement data when the error model obtained by the fitting processing unit 24 deviates from the actual error or when it is difficult to set the temporary model. be able to.
  • the NC device 1 can perform highly accurate correction of mechanical error by enabling selection between correction based on the above error model and correction based on spline interpolation.
  • the NC device 1 selects one of the correction based on the above error model obtained by the fitting processing unit 24 and the correction based on the above spline interpolation by the interpolation processing unit 25, and corrects the pitch error. Can be done.
  • the NC device 1 can select a correction based on the error model and a correction based on the spline interpolation according to the input operation to the input unit 14 by the user.
  • the NC device 1 selects one of the first error model, which is an error model obtained by fitting the tentative model, and the second error model, which is the error model obtained by fitting the polynomial model. Make it selectable.
  • the NC device 1 can select a correction based on the first error model and a correction based on the second error model for the correction based on the error model according to the input operation to the input unit 14 by the user. it can.
  • the interpolation processing unit 25 may be capable of performing linear interpolation of measurement data separately from spline interpolation.
  • the NC apparatus 1 can select either spline interpolation or linear interpolation for the correction based on the result of the interpolation processing.
  • the NC device 1 can select a correction based on spline interpolation and a correction based on linear interpolation according to an input operation to the input unit 14 by the user.
  • the NC device 1 performs arbitrary correction from the correction based on the first error model, the correction based on the second error model, the correction based on spline interpolation, and the correction based on linear interpolation. You can select and correct the runout error.
  • FIG. 8 is a diagram showing an example of a screen displayed on the display unit 20 included in the NC device 1 shown in FIG.
  • linear interpolation represents a correction format based on the above linear interpolation.
  • Spline interpolation represents a correction format based on the above spline interpolation.
  • Polynomial fitting represents a correction form based on the above second error model.
  • Tempoary model fitting represents a correction format based on the above-mentioned first error model. The user refers to the content displayed on the screen of the display unit 20 and specifies one of the correction formats by the operation of the input unit 14.
  • the run-out error processing unit 21 When the run-out error processing unit 21 receives a signal corresponding to the input operation from the input unit 14, it outputs error data for performing the specified correction to the error data storage unit 17.
  • the error data storage unit 17 stores the interpolation data as the error data, which is the result of linear interpolation by the interpolation processing unit 25.
  • the error data storage unit 17 stores the interpolation data as the error data, which is the result of spline interpolation by the interpolation processing unit 25.
  • the error data storage unit 17 stores a second error model as error data.
  • the error data storage unit 17 stores the first error model as error data.
  • the correction amount determination unit 16 determines the correction amount for the run-out error correction based on the error data read from the error data storage unit 17. As a result, the NC device 1 selects an arbitrary correction and corrects the runout error. Further, when “polynomial fitting" is specified, the NC device 1 may determine whether or not the regularization term is added by input by the user.
  • the display unit 20 may acquire the measurement data and the correction amount data based on the error model from the fitting processing unit 24, and display the measurement data and the correction amount data.
  • the correction amount data is obtained by sign inversion of the error data.
  • the display unit 20 may acquire the measurement data and the correction amount data based on the interpolation processing from the interpolation processing unit 25 and display the measurement data and the correction amount data. As a result, the user can confirm the effect of the correction on the measured error for each correction format.
  • the NC device 1 changes the value of the error amount displayed on the screen with respect to the error amount based on the second error model in accordance with the input operation of changing the value of "n" which is the highest degree of the polynomial. May be. As a result, the user can adjust the value of "n” while checking the amount of error.
  • the NC device 1 sets the value of the amount of error displayed on the screen of the second error model to which the regularization term is added as the input operation changes the value of the regularization parameter “ ⁇ ”. It may be changed. As a result, the user can adjust the value of " ⁇ " while checking the amount of error.
  • the NC device 1 may sample the command angle when the runout error is corrected and the command angle when the runout error is not corrected for the spindle 4.
  • the user can judge the effect of the improvement by the run-out error correction by confirming the difference between the two command angles based on the sampling result.
  • the user may measure the rotation angle when the runout error is corrected and the rotation angle when the runout error is not corrected by a measuring device, and confirm both rotation angles based on the measurement result. ..
  • Each functional unit of the NC device 1 shown in FIG. 1 is realized by executing a numerical control program, which is a program for executing the numerical control method according to the first embodiment, by using hardware.
  • FIG. 9 is a block diagram showing a hardware configuration of the NC device 1 according to the first embodiment of the present invention.
  • the NC device 1 includes a CPU (Central Processing Unit) 61 that executes various processes, a RAM (Random Access Memory) 62 that includes a data storage area, a ROM (Read Only Memory) 63 that is a non-volatile memory, and an external storage device. Has 64 and. Further, the NC device 1 has an input interface 65 for inputting information to the NC device 1, an input device 66 for receiving an input operation, and a display 67 for displaying information on the screen.
  • the parts shown in FIG. 9 are connected to each other via a bus 68.
  • the CPU 61 executes a program stored in the ROM 63 and the external storage device 64.
  • the functions of the program acquisition unit 10, the program analysis unit 11, the axis command generation unit 12, the data processing unit 15, the correction amount determination unit 16, the adder 18, and the drive command unit 19 shown in FIG. 1 are realized by using the CPU 61. Will be done.
  • the external storage device 64 is an HDD (Hard Disk Drive) or an SSD (Solid State Drive).
  • the external storage device 64 stores the numerical control program and various information.
  • the function of the error data storage unit 17 shown in FIG. 1 is realized by using the external storage device 64.
  • the ROM 63 is a boot loader such as a BIOS (Basic Input / Output System) or UEFI (Unified Extensible Firmware Interface), which is a program for basic control of a computer or controller which is an NC device 1, and controls hardware.
  • BIOS Basic Input / Output System
  • UEFI Unified Extensible Firmware Interface
  • the software or program is stored.
  • the numerical control program may be stored in the ROM 63.
  • the program stored in the ROM 63 and the external storage device 64 is loaded into the RAM 62.
  • the CPU 61 develops a numerical control program in the RAM 62 and executes various processes.
  • the input interface 65 is a connection interface with an external device of the NC device 1.
  • the function of the data acquisition unit 13 shown in FIG. 1 is realized by using the input interface 65.
  • the input device 66 is a device for inputting information, such as a keyboard or a pointing device.
  • the function of the input unit 14 shown in FIG. 1 is realized by using the input device 66.
  • the display 67 is a display device such as a liquid crystal display or an organic EL display.
  • the function of the display unit 20 shown in FIG. 1 is realized by using the display 67.
  • the numerical control program may be stored in a storage medium that can be read by a computer.
  • the NC device 1 may store the numerical control program stored in the storage medium in the external storage device 64.
  • the storage medium may be a portable storage medium that is a flexible disk, or a flash memory that is a semiconductor memory.
  • the numerical control program may be installed from another computer or server device to the computer or controller that becomes the NC device 1 via the communication network.
  • the function of the NC device 1 may be realized by a processing circuit which is dedicated hardware.
  • the processing circuit is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.
  • ASIC Application Specific Integrated Circuit
  • FPGA Field-Programmable Gate Array
  • Some of the functions of the NC device 1 may be realized by dedicated hardware, and some of the functions may be realized by software or firmware.
  • the NC device 1 is not limited to an external device of the machine tool 2, and may be included in the machine tool 2. Each functional unit of the NC device 1 is not limited to one integrated in one device, and may be distributed in a plurality of devices.
  • the NC device 1 may be realized by using one device, or may be realized by using a plurality of devices.
  • the method of correcting the runout error by the NC device 1 may be applied to the control of an industrial machine other than the machine tool 2.
  • the NC device 1 sets a tentative model in consideration of the structure of the mechanism by obtaining a model function representing a phenomenon that can occur in the mechanism, and fits the model function to the measurement data.
  • the NC device 1 can correct the mechanical error with high accuracy by fitting the temporary model.
  • the NC device 1 can reduce the burden required for measuring the error as compared with the case where the correction accuracy is improved by increasing the number of division points.
  • the NC device 1 can perform highly accurate correction of mechanical error by making it possible to select between correction based on the fitting of the tentative model, correction based on the fitting of the polynomial, and correction based on spline interpolation. ..
  • the NC device 1 has an effect that it is possible to correct the mechanical error caused by the displacement of the rotation axis with high accuracy.
  • the configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

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Abstract

This NC device controls a motor that is a drive source of a mechanism for rotating a tool or a workpiece in a machine tool that processes the workpiece by using the tool. The NC device comprises: a temporary model setting unit (23) which obtains a model function representing center deviation, which is a phenomenon in which the position of the rotation axis of the mechanism shifts, and sets a temporary model of a mechanical error due to the center deviation; a fitting processing unit (24) which obtains an error model that is a model of the mechanical error, by fitting the model function to measurement data that is a result of measuring the operation of the mechanism; and a correction unit which corrects a command to the motor on the basis of the error model.

Description

数値制御装置Numerical control device
　本発明は、産業用機械を制御する数値制御装置に関する。 The present invention relates to a numerical control device that controls an industrial machine.
　産業用機械である工作機械には、加工対象物であるワークまたは工具の回転角度を変化させるための機構である主軸等の駆動軸を有するものがある。かかる工作機械を制御する数値制御装置は、駆動軸を制御する。なお、以下の説明では、数値制御装置をＮＣ（Numerical　Control）装置と称することがある。特許文献１には、工作機械が有する主軸を制御するＮＣ装置が開示されている。 Some machine tools, which are industrial machines, have a drive shaft such as a spindle, which is a mechanism for changing the rotation angle of the work or tool that is the object to be machined. The numerical control device that controls such a machine tool controls the drive shaft. In the following description, the numerical control device may be referred to as an NC (Numerical Control) device. Patent Document 1 discloses an NC device that controls a spindle of a machine tool.
特開平２－３０９４０１号公報JP-A-2-309401
　ＮＣ装置による駆動軸の制御において、例えば主軸は、主軸の構造に起因して、指令に従った動作と実際の動作との間に誤差を生じることがある。このように、機構が持つ構造に起因して生じる誤差は、機械誤差と称される。主軸において生じる機械誤差には、回転軸の位置が本来の位置からずれる現象である芯振れに起因する機械誤差が挙げられる。工作機械による高精度な加工を可能とするために、上記特許文献１に開示される従来のＮＣ装置は、芯振れに起因する機械誤差を高精度に補正することが求められている。 In the control of the drive shaft by the NC device, for example, the spindle may cause an error between the operation according to the command and the actual operation due to the structure of the spindle. Such an error caused by the structure of the mechanism is called a mechanical error. Mechanical errors that occur in the spindle include mechanical errors caused by runout, which is a phenomenon in which the position of the rotating shaft deviates from the original position. In order to enable high-precision machining by a machine tool, the conventional NC apparatus disclosed in Patent Document 1 is required to correct mechanical errors due to runout with high accuracy.
　本発明は、上記に鑑みてなされたものであって、回転軸の位置がずれることに起因する機械誤差の高精度な補正を可能とする数値制御装置を得ることを目的とする。 The present invention has been made in view of the above, and an object of the present invention is to obtain a numerical control device capable of highly accurate correction of mechanical errors caused by a shift in the position of a rotating shaft.
　上述した課題を解決し、目的を達成するために、本発明にかかる数値制御装置は、工具を用いてワークを加工する工作機械において工具またはワークを回転動作させる機構の駆動源であるモータを制御する。本発明にかかる数値制御装置は、機構が有する回転軸の位置がずれる現象である芯振れを表すモデル関数を求めることによって、芯振れによる機械誤差の仮モデルを設定する仮モデル設定部と、機構の動作を測定した結果である測定データにモデル関数をフィッティングさせることによって機械誤差のモデルである誤差モデルを求めるフィッティング処理部と、誤差モデルに基づいてモータへの指令を補正する補正部と、を備える。 In order to solve the above-mentioned problems and achieve the object, the numerical control device according to the present invention controls a motor which is a drive source of a mechanism for rotating a tool or a work in a machine tool for machining a work using a tool. To do. The numerical control device according to the present invention has a temporary model setting unit and a mechanism for setting a temporary model of mechanical error due to center runout by obtaining a model function representing runout, which is a phenomenon in which the position of the rotation axis of the mechanism shifts. A fitting processing unit that obtains an error model, which is a model of mechanical error, by fitting a model function to the measurement data that is the result of measuring the operation of, and a correction unit that corrects commands to the motor based on the error model. Be prepared.
　本発明にかかる数値制御装置は、回転軸の位置がずれることに起因する機械誤差の高精度な補正が可能となるという効果を奏する。 The numerical control device according to the present invention has the effect of enabling highly accurate correction of mechanical errors caused by the displacement of the rotation axis.
本発明の実施の形態１にかかるＮＣ装置と、ＮＣ装置によって制御される工作機械とを示す図The figure which shows the NC apparatus which concerns on Embodiment 1 of this invention, and the machine tool controlled by NC apparatus. 図１に示すＮＣ装置によって制御される主軸における芯振れ誤差と周期誤差とについて説明する図The figure explaining the runout error and the periodic error in the spindle controlled by the NC apparatus shown in FIG. 図１に示すＮＣ装置が有する芯振れ誤差処理部を示すブロック図A block diagram showing a runout error processing unit included in the NC device shown in FIG. 図１に示すＮＣ装置によって制御される主軸のうち回転角度の検出のための構成を示す図The figure which shows the structure for detecting the rotation angle of the spindle controlled by the NC apparatus shown in FIG. 図１に示すＮＣ装置によって制御される主軸における芯振れ誤差について説明する第１の図The first figure explaining the runout error in the spindle controlled by the NC apparatus shown in FIG. 図１に示すＮＣ装置によって制御される主軸における芯振れ誤差について説明する第２の図The second figure explaining the runout error in the spindle controlled by the NC apparatus shown in FIG. 図１に示すＮＣ装置によって制御される主軸における芯振れ誤差について説明する第３の図FIG. 3 for explaining the runout error in the spindle controlled by the NC device shown in FIG. 図１に示すＮＣ装置が有する表示部に表示される画面の例を示す図The figure which shows the example of the screen displayed on the display part of the NC apparatus shown in FIG. 本発明の実施の形態１にかかるＮＣ装置のハードウェア構成を示すブロック図A block diagram showing a hardware configuration of an NC device according to a first embodiment of the present invention.
　以下に、本発明の実施の形態にかかる数値制御装置を図面に基づいて詳細に説明する。なお、この実施の形態によりこの発明が限定されるものではない。 The numerical control device according to the embodiment of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to this embodiment.
実施の形態１．
　図１は、本発明の実施の形態１にかかるＮＣ装置１と、ＮＣ装置１によって制御される工作機械２とを示す図である。工作機械２は、工具を用いてワーク５を加工する。工作機械２は、ワーク５と工具との相対位置を直線運動によって変化させる直線駆動軸３と、工具またはワーク５の回転角度を回転運動によって変化させる主軸４とを有する。図１には、ワーク５を回転させる主軸４を示している。主軸４は、回転軸であるシャフト３７を有する。図１では、工具の図示を省略している。 Embodiment 1.
FIG. 1 is a diagram showing an NC device 1 according to a first embodiment of the present invention and a machine tool 2 controlled by the NC device 1. The machine tool 2 processes the work 5 using a tool. The machine tool 2 has a linear drive shaft 3 that changes the relative position between the work 5 and the tool by a linear motion, and a spindle 4 that changes the rotation angle of the tool or the work 5 by a rotary motion. FIG. 1 shows a spindle 4 for rotating the work 5. The main shaft 4 has a shaft 37 which is a rotation shaft. In FIG. 1, the illustration of the tool is omitted.
　直線駆動軸３は、直線駆動軸３の駆動源であるサーボモータ３２と、サーボモータ３２を動作させるサーボアンプ３１と、サーボモータ３２の駆動によって回転するボールねじ３３と、ボールねじ３３の回転によってボールねじ３３の中心軸に平行な軸方向へ移動する移動体３４とを有する。直線駆動軸３は、ボールねじ３３の回転運動を直線運動に変換する機構である。サーボアンプ３１は、ＮＣ装置１から出力される軸指令にしたがってサーボモータ３２を動作させる。ＮＣ装置１は、サーボアンプ３１へ軸指令を出力することによって、サーボモータ３２を制御する。 The linear drive shaft 3 is formed by the servomotor 32 that is the drive source of the linear drive shaft 3, the servo amplifier 31 that operates the servomotor 32, the ball screw 33 that is rotated by driving the servomotor 32, and the ball screw 33 that is rotated. It has a moving body 34 that moves in an axial direction parallel to the central axis of the ball screw 33. The linear drive shaft 3 is a mechanism that converts the rotational motion of the ball screw 33 into a linear motion. The servo amplifier 31 operates the servomotor 32 according to the axis command output from the NC device 1. The NC device 1 controls the servomotor 32 by outputting an axis command to the servo amplifier 31.
　主軸４は、主軸４の駆動源である主軸モータ３６と、主軸モータ３６を動作させる主軸アンプ３５とを有する。チャック３８は、主軸モータ３６の出力軸であるシャフト３７にワーク５を固定させる。主軸４は、シャフト３７に取り付けられたワーク５を回転させる機構である。主軸アンプ３５は、ＮＣ装置１から出力される軸指令にしたがって主軸モータ３６を動作させる。ＮＣ装置１は、主軸アンプ３５へ軸指令を出力することによって、主軸モータ３６を制御する。 The spindle 4 has a spindle motor 36 that is a drive source of the spindle 4 and a spindle amplifier 35 that operates the spindle motor 36. The chuck 38 fixes the work 5 to the shaft 37, which is the output shaft of the spindle motor 36. The spindle 4 is a mechanism for rotating the work 5 attached to the shaft 37. The spindle amplifier 35 operates the spindle motor 36 according to the axis command output from the NC device 1. The NC device 1 controls the spindle motor 36 by outputting an axis command to the spindle amplifier 35.
　ＮＣ装置１は、加工プログラムを取得するプログラム取得部１０と、取得された加工プログラムを解析するプログラム解析部１１と、プログラム解析部１１による解析結果を基に軸指令を生成する軸指令生成部１２とを有する。軸指令生成部１２は、直線駆動軸３に対する軸指令と主軸４に対する軸指令とを生成する。軸指令生成部１２は、生成された軸指令を加算器１８と補正量決定部１６とへ出力する。 The NC device 1 includes a program acquisition unit 10 for acquiring a machining program, a program analysis unit 11 for analyzing the acquired machining program, and an axis command generation unit 12 for generating an axis command based on the analysis result by the program analysis unit 11. And have. The axis command generation unit 12 generates an axis command for the linear drive shaft 3 and an axis command for the spindle 4. The axis command generation unit 12 outputs the generated axis command to the adder 18 and the correction amount determination unit 16.
　ＮＣ装置１は、機械誤差の測定データを取得するデータ取得部１３と、情報入力のための操作を受け付ける入力部１４と、測定データの処理を実行するデータ処理部１５と、情報を表示する表示部２０とを有する。データ処理部１５は、芯振れ誤差補正についてのデータ処理を担う芯振れ誤差処理部２１と、周期誤差補正についてのデータ処理を担う周期誤差処理部２２とを有する。芯振れ誤差処理部２１と周期誤差処理部２２との詳細については後述する。 The NC device 1 includes a data acquisition unit 13 for acquiring measurement data of machine error, an input unit 14 for receiving an operation for inputting information, a data processing unit 15 for executing measurement data processing, and a display for displaying information. It has a part 20 and. The data processing unit 15 has a runout error processing unit 21 that is responsible for data processing for runout error correction, and a periodic error processing unit 22 that is responsible for data processing for periodic error correction. The details of the runout error processing unit 21 and the periodic error processing unit 22 will be described later.
　主軸４の機械誤差は、測定機器によって測定される。図１では、測定機器の図示を省略している。データ取得部１３は、測定機器による測定結果である測定データを取り込む。入力部１４には、ＮＣ装置１のユーザの操作によって、データ処理部１５における処理に関する情報が入力される。データ処理部１５は、データ取得部１３から取り込んだ測定データと入力部１４へ入力された情報とを基に、データ処理を実行する。表示部２０は、データ処理部１５における処理に関する情報を表示する。 The mechanical error of the spindle 4 is measured by a measuring device. In FIG. 1, the illustration of the measuring device is omitted. The data acquisition unit 13 acquires measurement data which is a measurement result by the measuring device. Information about the processing in the data processing unit 15 is input to the input unit 14 by the operation of the user of the NC device 1. The data processing unit 15 executes data processing based on the measurement data fetched from the data acquisition unit 13 and the information input to the input unit 14. The display unit 20 displays information related to processing in the data processing unit 15.
　データ処理部１５は、データ処理の結果である誤差データを誤差データ格納部１７へ出力する。誤差データ格納部１７は、誤差データを格納する。補正量決定部１６は、誤差データ格納部１７から読み出された誤差データを基に、機械誤差を補正するための補正量を決定する。補正量決定部１６は、主軸４について、指令された回転角度とのずれを相殺するための角度である補正量を決定する。補正量決定部１６は、決定された補正量を加算器１８へ出力する。 The data processing unit 15 outputs the error data that is the result of the data processing to the error data storage unit 17. The error data storage unit 17 stores the error data. The correction amount determination unit 16 determines the correction amount for correcting the mechanical error based on the error data read from the error data storage unit 17. The correction amount determination unit 16 determines the correction amount, which is an angle for canceling the deviation from the commanded rotation angle of the spindle 4. The correction amount determination unit 16 outputs the determined correction amount to the adder 18.
　加算器１８は、主軸４に対する指令角度の値に、決定された補正量を加算する。補正量決定部１６および加算器１８は、主軸モータ３６への指令を補正する補正部として機能する。加算器１８は、補正量の加算を経た軸指令を駆動指令部１９へ出力する。駆動指令部１９は、主軸４に対する軸指令を主軸アンプ３５へ出力する。なお、ＮＣ装置１は、主軸４が工具を回転させる機構である場合も、主軸４がワーク５を回転させる機構である場合と同様に、主軸４に対する軸指令を補正することができる。 The adder 18 adds the determined correction amount to the value of the command angle with respect to the spindle 4. The correction amount determining unit 16 and the adder 18 function as a correction unit for correcting a command to the spindle motor 36. The adder 18 outputs an axis command after the correction amount has been added to the drive command unit 19. The drive command unit 19 outputs a shaft command for the spindle 4 to the spindle amplifier 35. Note that the NC device 1 can correct the axis command to the spindle 4 even when the spindle 4 is a mechanism for rotating the tool, as in the case where the spindle 4 is a mechanism for rotating the work 5.
　ＮＣ装置１は、直線駆動軸３についても、補正量決定部１６と加算器１８とにより軸指令の補正を行う。実施の形態１では、直線駆動軸３に対する軸指令の補正については説明を省略する。 The NC device 1 also corrects the shaft command for the linear drive shaft 3 by the correction amount determining unit 16 and the adder 18. In the first embodiment, the description of the correction of the axis command with respect to the linear drive shaft 3 will be omitted.
　次に、芯振れ誤差補正と周期誤差補正とについて説明する。図２は、図１に示すＮＣ装置１によって制御される主軸４における芯振れ誤差と周期誤差とについて説明する図である。主軸４は、チャック３８、ワーク５または工具の重量の偏りに起因して、芯振れを生じる。芯振れは、シャフト３７の位置が本来の位置からずれる現象である。芯振れにより、シャフト３７の回転中心位置は、シャフト３７の中心軸に垂直な方向においてシフトする。主軸４の芯振れによる誤差は、主軸４に生じる機械誤差の主な成分となる。上記の測定機器は、主軸４の１回転の角度範囲を複数に分割して、シャフト３７の実際の回転角度と指令角度との誤差を分割点ごとに測定する。ＮＣ装置１は、測定データから得られた誤差モデルまたは測定データから得られた補間データを基に指令角度を補正する。このように、ＮＣ装置１は、主軸４について、分割点ごとの誤差の測定データを基に機械誤差を低減し得る。ＮＣ装置１は、分割点ごとの誤差の測定データを基に指令位置または指令角度を補正することにより、芯振れ誤差補正を行う。 Next, the runout error correction and the periodic error correction will be described. FIG. 2 is a diagram illustrating a runout error and a periodic error in the spindle 4 controlled by the NC device 1 shown in FIG. The spindle 4 causes runout due to the uneven weight of the chuck 38, the work 5, or the tool. Center runout is a phenomenon in which the position of the shaft 37 deviates from the original position. Due to the runout, the rotation center position of the shaft 37 shifts in the direction perpendicular to the center axis of the shaft 37. The error due to the runout of the spindle 4 is a main component of the mechanical error generated in the spindle 4. The above-mentioned measuring device divides the angle range of one rotation of the spindle 4 into a plurality of parts, and measures the error between the actual rotation angle of the shaft 37 and the command angle for each division point. The NC device 1 corrects the command angle based on the error model obtained from the measurement data or the interpolation data obtained from the measurement data. In this way, the NC device 1 can reduce the mechanical error of the spindle 4 based on the measurement data of the error at each division point. The NC device 1 corrects the runout error by correcting the command position or the command angle based on the measurement data of the error for each division point.
　ここで、図２に示される芯振れ誤差を表す波形の周期は、主軸４の回転周期と同期している。図２に示される芯振れ誤差の周期は、主軸４の回転周期と一致している。 Here, the period of the waveform representing the runout error shown in FIG. 2 is synchronized with the rotation period of the spindle 4. The period of the runout error shown in FIG. 2 coincides with the rotation period of the spindle 4.
　主軸４に生じる機械誤差には、芯振れ誤差成分と、周期的に発生する誤差である周期誤差成分とが含まれている。主軸４の周期誤差は、主軸モータ３６に取り付けられている位置検出器に起因して生じる。位置検出器は、主軸モータ３６の回転角度を検出する。主軸アンプ３５は、位置検出器によって検出された回転角度の値が指令位置に追従するように主軸モータ３６を駆動する。図１では、主軸モータ３６における位置検出器の図示を省略している。以下の説明にて、周期誤差補正とは、誤差モデルを任意の波形と定め、かつ任意の周期を定めて周期的に誤差を補正することを指すものとする。なお、図２に示すように、周期誤差は芯振れ誤差の周期よりも短い周期で振動する特性を有する。ＮＣ装置１は、主軸４について、芯振れ誤差成分についての補正である芯振れ誤差補正と周期誤差成分についての補正である周期誤差補正との併用によって、機械誤差を補正する。 The mechanical error that occurs in the spindle 4 includes a runout error component and a periodic error component that is an error that occurs periodically. The periodic error of the spindle 4 is caused by the position detector attached to the spindle motor 36. The position detector detects the rotation angle of the spindle motor 36. The spindle amplifier 35 drives the spindle motor 36 so that the value of the rotation angle detected by the position detector follows the commanded position. In FIG. 1, the position detector in the spindle motor 36 is not shown. In the following description, periodic error correction refers to defining an error model as an arbitrary waveform and defining an arbitrary period to periodically correct the error. As shown in FIG. 2, the periodic error has a characteristic of vibrating in a period shorter than the period of the runout error. The NC device 1 corrects the mechanical error of the spindle 4 by using both the runout error correction, which is a correction for the runout error component, and the periodic error correction, which is a correction for the periodic error component.
　データ取得部１３は、主軸４について、分割点ごとにおける誤差の測定データを取得する。芯振れ誤差処理部２１は、かかる測定データを基に、芯振れ誤差補正のためのデータ処理を実行する。誤差データ格納部１７は、芯振れ誤差処理部２１でのデータ処理によって得られた誤差モデルまたは補間データである誤差データを格納する。芯振れ誤差処理部２１の詳細については後述する。 The data acquisition unit 13 acquires measurement data of an error at each division point for the spindle 4. The runout error processing unit 21 executes data processing for correcting the runout error based on the measurement data. The error data storage unit 17 stores error data which is an error model or interpolated data obtained by data processing in the runout error processing unit 21. The details of the runout error processing unit 21 will be described later.
　データ取得部１３は、主軸４に生じる周期誤差の測定データを取得する。周期誤差処理部２２は、かかる測定データを基に、周期誤差補正のためのデータ処理を実行する。周期誤差処理部２２は、測定データを基に任意の周期を定めるとともに、周期的な補正のための誤差データを求める。誤差データ格納部１７は、周期誤差処理部２２でのデータ処理によって得られた誤差データを格納する。 The data acquisition unit 13 acquires the measurement data of the periodic error generated in the spindle 4. The periodic error processing unit 22 executes data processing for correcting the periodic error based on the measured data. The periodic error processing unit 22 determines an arbitrary period based on the measurement data, and obtains error data for periodic correction. The error data storage unit 17 stores the error data obtained by the data processing in the periodic error processing unit 22.
　補正量決定部１６は、主軸４の芯振れ誤差補正と主軸４の周期誤差補正とについて、軸指令における指令位置に対応する誤差量を誤差データ格納部１７から読み出す。補正量決定部１６は、読み出された誤差量の値を符号反転させることによって、指令位置に対応する補正量の値を求める。補正量決定部１６は、芯振れ誤差補正と周期誤差補正とについて、指令位置に対応する補正量を決定する。補正量決定部１６は、主軸４について、芯振れ誤差補正のための補正量と周期誤差補正のための補正量との和を求め、求めた和を加算器１８へ出力する。このようにして、ＮＣ装置１は、芯振れ誤差補正のための補正量と周期誤差補正のための補正量との和を、機械誤差を補正するための補正量に設定して、主軸４についての軸指令を補正する。 The correction amount determination unit 16 reads out the error amount corresponding to the command position in the axis command from the error data storage unit 17 for the runout error correction of the spindle 4 and the periodic error correction of the spindle 4. The correction amount determination unit 16 obtains the value of the correction amount corresponding to the command position by sign-inverting the value of the read error amount. The correction amount determination unit 16 determines the correction amount corresponding to the command position for the runout error correction and the periodic error correction. The correction amount determination unit 16 obtains the sum of the correction amount for the runout error correction and the correction amount for the periodic error correction for the spindle 4, and outputs the obtained sum to the adder 18. In this way, the NC device 1 sets the sum of the correction amount for the runout error correction and the correction amount for the periodic error correction as the correction amount for correcting the mechanical error, and the spindle 4 is set. Correct the axis command of.
　次に、芯振れ誤差処理部２１について説明する。図３は、図１に示すＮＣ装置１が有する芯振れ誤差処理部２１を示すブロック図である。芯振れ誤差処理部２１は、機構に生じ得る機械誤差の要因である現象を表すモデル関数を求めることによって、機械誤差の仮モデルを設定する仮モデル設定部２３を有する。芯振れ誤差処理部２１は、機構の動作を測定した結果である測定データにモデル関数をフィッティングさせることによって機械誤差のモデルである誤差モデルを求めるフィッティング処理部２４を有する。また、芯振れ誤差処理部２１は、測定データの補間処理を実行する補間処理部２５を有する。 Next, the runout error processing unit 21 will be described. FIG. 3 is a block diagram showing a runout error processing unit 21 included in the NC device 1 shown in FIG. The runout error processing unit 21 has a tentative model setting unit 23 that sets a tentative model of the mechanical error by obtaining a model function representing a phenomenon that is a factor of the mechanical error that can occur in the mechanism. The runout error processing unit 21 has a fitting processing unit 24 that obtains an error model that is a model of mechanical error by fitting a model function to the measurement data that is the result of measuring the operation of the mechanism. In addition, the runout error processing unit 21 has an interpolation processing unit 25 that executes an interpolation processing of measurement data.
　ＮＣ装置１は、機構が持つ構造を考慮した仮モデルを設定し、仮モデルのモデル関数を測定データにフィッティングさせることによって誤差モデルを求める。モデル関数の周期は、シャフト３７の回転周期と同期している。ＮＣ装置１は、誤差モデルを基に、ピッチ誤差補正のための補正量を決定する。ＮＣ装置１は、誤差モデルが実際の誤差とは外れる場合、または、仮モデルの設定が困難である場合において、測定データのスプライン補間によって補正量を決定可能とする。 The NC device 1 sets a tentative model in consideration of the structure of the mechanism, and obtains an error model by fitting the model function of the tentative model to the measurement data. The period of the model function is synchronized with the rotation period of the shaft 37. The NC device 1 determines the correction amount for pitch error correction based on the error model. The NC device 1 makes it possible to determine the correction amount by spline interpolation of the measurement data when the error model deviates from the actual error or when it is difficult to set the temporary model.
　以下、芯振れ誤差処理部２１による処理について説明する。図４は、図１に示すＮＣ装置１によって制御される主軸４のうち回転角度の検出のための構成を示す図である。図４では、図１に示す主軸４のうちのシャフト３７と位置検出器４０とを示している。位置検出器４０は、発光体である発光ダイオード４１と、固定スリット４２と、受光体であるフォトダイオード４３とを有する。 Hereinafter, the processing by the runout error processing unit 21 will be described. FIG. 4 is a diagram showing a configuration for detecting a rotation angle of the spindle 4 controlled by the NC device 1 shown in FIG. FIG. 4 shows a shaft 37 and a position detector 40 of the spindle 4 shown in FIG. The position detector 40 has a light emitting diode 41 which is a light emitting body, a fixed slit 42, and a photodiode 43 which is a light receiving body.
　フォトダイオード４３は、発光ダイオード４１からの光を検出する。固定スリット４２は、発光ダイオード４１とフォトダイオード４３との間に配置されている。固定スリット４２には、それぞれ光が通過可能なＡ相スリット４５とＢ相スリット４６とが設けられている。フォトダイオード４３は、Ａ相スリット４５を通過した光とＢ相スリット４６を通過した光とを検出する。フォトダイオード４３は、Ａ相スリット４５を通過した光の検出結果を示すＡ相信号とＢ相スリット４６を通過した光の検出結果を示すＢ相信号とを出力する。 The photodiode 43 detects the light from the light emitting diode 41. The fixed slit 42 is arranged between the light emitting diode 41 and the photodiode 43. The fixed slit 42 is provided with an A-phase slit 45 and a B-phase slit 46, respectively, through which light can pass. The photodiode 43 detects light that has passed through the A-phase slit 45 and light that has passed through the B-phase slit 46. The photodiode 43 outputs an A-phase signal indicating a detection result of light passing through the A-phase slit 45 and a B-phase signal indicating a detection result of light passing through the B-phase slit 46.
　シャフト３７には、シャフト３７とともに回転する回転盤４４が取り付けられている。回転盤４４の中心は、シャフト３７の軸心に一致している。回転盤４４は、シャフト３７を中心に回転する。回転盤４４の外周には、等間隔に並べられた複数の歯が設けられている。発光ダイオード４１からの光は、歯に到達することによってフォトダイオード４３への入射が遮られ、歯と歯の間を通過した場合にフォトダイオード４３へ入射する。 A turntable 44 that rotates together with the shaft 37 is attached to the shaft 37. The center of the turntable 44 coincides with the axis of the shaft 37. The turntable 44 rotates about the shaft 37. A plurality of teeth arranged at equal intervals are provided on the outer circumference of the turntable 44. The light from the light emitting diode 41 is blocked from entering the photodiode 43 by reaching the teeth, and enters the photodiode 43 when passing between the teeth.
　位置検出器４０は、Ａ相信号のパルス数とＢ相信号のパルス数とを基に、Ａ相スリット４５およびＢ相スリット４６の双方の前を通過した歯の数をカウントする。位置検出器４０は、歯のカウント数を基に、シャフト３７の回転角度を検出する。位置検出器４０は、Ａ相信号とＢ相信号との位相差を基に、シャフト３７の回転方向を検出する。 The position detector 40 counts the number of teeth that have passed in front of both the A-phase slit 45 and the B-phase slit 46 based on the number of pulses of the A-phase signal and the number of pulses of the B-phase signal. The position detector 40 detects the rotation angle of the shaft 37 based on the number of teeth counted. The position detector 40 detects the rotation direction of the shaft 37 based on the phase difference between the A-phase signal and the B-phase signal.
　図５は、図１に示すＮＣ装置１によって制御される主軸４における芯振れ誤差について説明する第１の図である。図６は、図１に示すＮＣ装置１によって制御される主軸４における芯振れ誤差について説明する第２の図である。図５および図６では、位置検出器４０と回転盤４４との位置関係の変化について説明する。主軸モータ３６の芯振れによる機械誤差が主軸４に生じた場合に、シャフト３７とともに回転盤４４が移動することによって、位置検出器４０と回転盤４４との位置関係が変化する。 FIG. 5 is a first diagram illustrating a runout error in the spindle 4 controlled by the NC device 1 shown in FIG. FIG. 6 is a second diagram illustrating a runout error in the spindle 4 controlled by the NC device 1 shown in FIG. 5 and 6 show changes in the positional relationship between the position detector 40 and the turntable 44. When a mechanical error occurs in the spindle 4 due to the runout of the spindle motor 36, the rotary disk 44 moves together with the shaft 37, so that the positional relationship between the position detector 40 and the rotary disk 44 changes.
　図５には、芯振れが生じていない場合における回転盤４４について、回転盤４４が有する複数の歯のうちの１つの歯４７が位置検出器４０によって検出されたときの状態を示している。点Ｏは、芯振れが生じていない場合における回転盤４４の中心とする。 FIG. 5 shows the state of the turntable 44 when the runout does not occur, when one of the plurality of teeth 47 of the turntable 44 is detected by the position detector 40. The point O is the center of the turntable 44 when runout does not occur.
　図６には、芯振れが生じた場合における回転盤４４を示している。点Ｃは、芯振れが生じた場合における回転盤４４の中心とする。図６に示す例では、芯振れによる回転盤４４の移動量、すなわち点Ｏと点Ｃとの間の長さは「ｄ」であるものとする。また、回転盤４４の移動によって、回転盤４４が有する複数の歯のうち、上記の歯４７とは異なる１つの歯４８が位置検出器４０によって検出されたとする。歯４７と歯４８との間の角度が、主軸モータ３６の芯振れによる主軸４の機械誤差である誤差Ｅに相当する。 FIG. 6 shows the turntable 44 when runout occurs. The point C is the center of the turntable 44 when runout occurs. In the example shown in FIG. 6, it is assumed that the amount of movement of the rotating disk 44 due to the runout, that is, the length between the points O and C is "d". Further, it is assumed that, due to the movement of the turntable 44, one tooth 48 different from the above-mentioned tooth 47 is detected by the position detector 40 among the plurality of teeth of the turntable 44. The angle between the teeth 47 and the teeth 48 corresponds to an error E, which is a mechanical error of the spindle 4 due to the runout of the spindle motor 36.
　図７は、図１に示すＮＣ装置１によって制御される主軸４における芯振れ誤差について説明する第３の図である。図７では、図６に示す芯振れの現象のモデル化を例として、仮モデル設定部２３に設定される仮モデルについて説明する。図７において、第１の軸であるＸ軸と第２の軸であるＹ軸とは、互いに垂直な２軸とする。Ｘ軸とＹ軸との原点は、点Ｏとする。また、図７には、回転盤４４の平面形状を単純化した円５１，５２を表している。円５１は、芯振れが生じていない場合における回転盤４４を表している。円５２は、芯振れが生じた場合における回転盤４４を表している。また、円５１，５２の半径はそれぞれ「Ｐ」であるものとする。円５１の中心点は、点Ｏに一致している。 FIG. 7 is a third diagram illustrating a runout error in the spindle 4 controlled by the NC device 1 shown in FIG. In FIG. 7, the tentative model set in the tentative model setting unit 23 will be described by taking the modeling of the runout phenomenon shown in FIG. 6 as an example. In FIG. 7, the X-axis, which is the first axis, and the Y-axis, which is the second axis, are two axes that are perpendicular to each other. The origin of the X-axis and the Y-axis is the point O. Further, FIG. 7 shows circles 51 and 52 in which the planar shape of the turntable 44 is simplified. The circle 51 represents the turntable 44 when the runout does not occur. The circle 52 represents the turntable 44 when runout occurs. Further, it is assumed that the radii of the circles 51 and 52 are "P", respectively. The center point of the circle 51 coincides with the point O.
　図７では、図６と同様に、芯振れによる回転盤４４の移動量は「ｄ」である。回転盤４４の中心点は、芯振れによって移動する。円５２の中心である点Ｃは、芯振れが生じているときにおける回転盤４４の中心点である。点Ｃは、芯振れによって、円５３に沿って移動するものとする。円５３は、点Ｏが中心であってかつ半径が「ｄ」である円である。芯振れの現象によって、シャフト３７が１回転する間に点Ｃが円５３を１周するものとする。 In FIG. 7, as in FIG. 6, the amount of movement of the rotating disk 44 due to the runout is “d”. The center point of the turntable 44 moves due to runout. The point C, which is the center of the circle 52, is the center point of the rotating disk 44 when runout occurs. It is assumed that the point C moves along the circle 53 due to the runout. The circle 53 is a circle whose center is the point O and whose radius is “d”. It is assumed that the point C goes around the circle 53 once while the shaft 37 makes one rotation due to the phenomenon of center runout.
　円５１は、次の式（１）によって表される。また、円５３は、次の式（２）によって表される。 The circle 51 is represented by the following equation (1). Further, the circle 53 is represented by the following equation (2).
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000005
Figure JPOXMLDOC01-appb-M000005
　Ｘ軸上の点Ｃ’について、線分ＯＣ’と線分Ｃ’Ｃとが互いに垂直であるとして、∠ＣＯＣ’＝θとする。ここで、θは、芯振れによって移動した中心点である点Ｃと点Ｏとを結ぶ線分ＯＣとＸ軸とがなす角度である。円５２は、次の式（３）によって表される。なお、円５２とＹ軸との交点である点Ａは、図６に示す歯４８の位置を表している。Ｙ＞０における線分Ｃ’Ｃの延長線と円５２との交点である点Ｂ’は、図６に示す歯４７の位置を表している。 Regarding the point C'on the X-axis, ∠COC'= θ, assuming that the line segment OC'and the line segment C'C are perpendicular to each other. Here, θ is the angle formed by the line segment OC connecting the points C and O, which are the center points moved by the runout, and the X-axis. The circle 52 is represented by the following equation (3). The point A, which is the intersection of the circle 52 and the Y-axis, represents the position of the tooth 48 shown in FIG. The point B', which is the intersection of the extension line of the line segment C'C and the circle 52 at Y> 0, represents the position of the tooth 47 shown in FIG.
Figure JPOXMLDOC01-appb-M000006
Figure JPOXMLDOC01-appb-M000006
　線分ＣＢ’上の点Ｂについて、線分ＣＢと線分ＡＢとが互いに垂直であるとして、線分ＡＢの長さは、次の式（４）によって表される。式（４）において、「ＡＢ」は線分ＡＢの長さ、「Ｏ’Ｃ」は線分Ｏ’Ｃの長さ、「ＯＣ’」は線分ＯＣ’の長さをそれぞれ表すものとする。 Regarding the point B on the line segment CB', assuming that the line segment CB and the line segment AB are perpendicular to each other, the length of the line segment AB is expressed by the following equation (4). In equation (4), "AB" represents the length of the line segment AB, "O'C" represents the length of the line segment O'C, and "OC'" represents the length of the line segment OC'. ..
Figure JPOXMLDOC01-appb-M000007
Figure JPOXMLDOC01-appb-M000007
　線分ＡＣの長さは、円５２の半径である「Ｐ」である。∠ＡＣＢ＝αとすると、上記の数４により、次の式（５）が成り立つ。また、式（５）により、次の式（６）が成り立つ。式（５）において、「ＡＢ」は線分ＡＢの長さ、「ＡＣ」は線分ＡＣの長さをそれぞれ表すものとする。 The length of the line segment AC is "P", which is the radius of the circle 52. Assuming that ∠ACB = α, the following equation (5) is established by the above equation 4. Further, the following equation (6) is established by the equation (5). In the formula (5), "AB" represents the length of the line segment AB, and "AC" represents the length of the line segment AC.
Figure JPOXMLDOC01-appb-M000008
Figure JPOXMLDOC01-appb-M000008
Figure JPOXMLDOC01-appb-M000009
Figure JPOXMLDOC01-appb-M000009
　ここで、上記の式（６）に示す「Ｐ／ｄ」を「Ｐ’」と置き換える。また、上記の「θ」の基準位置が未知であることを考慮し、上記の式（６）に示す「θ」を「θ＋φ」と置き換える。「＋φ」は、φの位相が付加されたことを表す。これらの置き換えにより、上記の式（６）は、次の式（７）のように表される。θ+φは、点Ｏを基準とする回転盤４４の中心点の方角を示す角度の、芯振れによる変化量を表す。 Here, "P / d" shown in the above equation (6) is replaced with "P'". Further, considering that the reference position of the above "θ" is unknown, "θ" shown in the above equation (6) is replaced with "θ + φ". “+ Φ” indicates that the phase of φ has been added. By these replacements, the above equation (6) is expressed as the following equation (7). θ + φ represents the amount of change due to runout of the angle indicating the direction of the center point of the rotating disk 44 with respect to the point O.
Figure JPOXMLDOC01-appb-M000010
Figure JPOXMLDOC01-appb-M000010
　上記の式（７）に示す「α」は、上記の誤差Ｅに相当する角度である。式（７）は、主軸モータ３６の芯振れによる主軸４の機械誤差についてのモデル関数を表す。図３に示す仮モデル設定部２３は、芯振れの現象による機械誤差について、上記の式（７）に示すようなモデル関数を、仮モデルに設定する。このように、仮モデル設定部２３は、芯振れの現象について、簡易的なモデル化によって仮モデルを設定することができる。 "Α" shown in the above equation (7) is an angle corresponding to the above error E. Equation (7) represents a model function for the mechanical error of the spindle 4 due to the runout of the spindle motor 36. The temporary model setting unit 23 shown in FIG. 3 sets a model function as shown in the above equation (7) in the temporary model for the mechanical error due to the phenomenon of runout. In this way, the temporary model setting unit 23 can set the temporary model by simple modeling for the phenomenon of runout.
　仮モデル設定部２３は、ユーザによる入力操作にしたがって、仮モデルを設定するまでの処理を行う。仮モデル設定部２３は、ユーザによって入力された条件値を用いて仮モデルを生成する。条件値は、上記の「Ｐ」および「ｄ」などである。仮モデル設定部２３は、ＮＣ装置１の外部の装置によって作成されたモデル関数を取得することによって、仮モデルを設定することとしても良い。なお、仮モデル設定部２３は、芯振れによる点Ｃの軌跡を、円に限られず、楕円としても良い。仮モデル設定部２３は、主軸モータ３６の特性に応じて、点Ｃの軌跡を示す形状を適宜設定可能であっても良い。 The temporary model setting unit 23 performs processing until the temporary model is set according to the input operation by the user. The tentative model setting unit 23 generates a tentative model using the condition values input by the user. The condition values are the above-mentioned "P" and "d" and the like. The tentative model setting unit 23 may set the tentative model by acquiring a model function created by an external device of the NC device 1. The temporary model setting unit 23 may make the locus of the point C due to the runout not only a circle but also an ellipse. The temporary model setting unit 23 may be able to appropriately set the shape indicating the locus of the point C according to the characteristics of the spindle motor 36.
　次に、芯振れによる主軸４の機械誤差についてのモデル関数を例として、測定データへの仮モデルのフィッティングについて説明する。フィッティング処理部２４は、最小二乗法によるフィッティングを行う。上記の式（７）は、「θ」、「φ」および「Ｐ’」を引数とする多変数関数である。上記の式（７）は、次の式（８）のように書き換えられる。 Next, the fitting of the tentative model to the measurement data will be described using a model function for the mechanical error of the spindle 4 due to runout as an example. The fitting processing unit 24 performs fitting by the least squares method. The above equation (7) is a multivariable function with "θ", "φ" and "P'" as arguments. The above equation (7) can be rewritten as the following equation (8).
Figure JPOXMLDOC01-appb-M000011
Figure JPOXMLDOC01-appb-M000011
　主軸４の１回転の角度範囲をｍ分割したとして、主軸４の芯振れによる誤差についての測定データが｛（θｉ，ｚｉ）；ｉ＝１，・・・，ｍ｝であったとする。「ｍ」は２以上の整数とする。「θｉ」は、指令に応じた回転角度であって、分割点の１つであるｉ番目のポイントにおける回転角度とする。「ｚｉ」は、ｉ番目のポイントにおいて測定された誤差とする。 It is assumed that the angle range of one rotation of the spindle 4 is divided into m, and the measurement data for the error due to the runout of the spindle 4 is {(θ i , z i ); i = 1, ..., M}. “M” is an integer of 2 or more. “Θ i ” is a rotation angle according to the command, and is a rotation angle at the i-th point, which is one of the division points. "Z i" is been an error measured in the i-th point.
　フィッティング処理部２４は、次の式（９）に示される「Ｊ」の関数を最小化させる「φ」および「Ｐ’」を求めることにより、フィッティングを行う。 The fitting processing unit 24 performs fitting by obtaining "φ" and "P'" that minimize the function of "J" shown in the following equation (9).
Figure JPOXMLDOC01-appb-M000012
Figure JPOXMLDOC01-appb-M000012
　フィッティング処理部２４は、非線形最小二乗法によって、非線形の誤差モデルを求める。フィッティング処理部２４によるフィッティングには、代表的な非線形最小二乗法であるガウス・ニュートン法を用いることができる。フィッティングには、ガウス・ニュートン法以外の方法を用いても良い。フィッティング処理部２４は、フィッティングによって求めた誤差モデルを誤差データ格納部１７へ出力する。 The fitting processing unit 24 obtains a non-linear error model by the non-linear least squares method. For fitting by the fitting processing unit 24, the Gauss-Newton method, which is a typical nonlinear least squares method, can be used. For fitting, a method other than the Gauss-Newton method may be used. The fitting processing unit 24 outputs the error model obtained by fitting to the error data storage unit 17.
　フィッティング処理部２４は、上記の仮モデルへのフィッティングに代えて、１変数の多項式を測定データへフィッティングさせることによって誤差モデルを求めることもできる。フィッティング処理部２４は、上記の式（９）によって求めた誤差モデルが実際の誤差から外れたものとなる場合に、多項式によるフィッティングによって、実際の誤差に近い誤差モデルを得られる場合がある。 The fitting processing unit 24 can also obtain an error model by fitting a polynomial of one variable to the measurement data instead of fitting to the above-mentioned tentative model. When the error model obtained by the above equation (9) deviates from the actual error, the fitting processing unit 24 may obtain an error model close to the actual error by fitting with a polynomial.
　多項式によるフィッティングにおいて、フィッティング処理部２４は、誤差モデルを、次の式（１０）によって表されるｎ次多項式と仮定する。式（１０）は、「θ」を変数とする多項式である。「ｃｋ」は、ｋ次の項の係数を表す。「ｎ」は２以上の整数とする。「ｋ」は０からｎの整数を表す変数とする。 In the fitting by the polynomial, the fitting processing unit 24 assumes that the error model is an nth-order polynomial represented by the following equation (10). Equation (10) is a polynomial with "θ" as a variable. “ Ck ” represents the coefficient of the k-th order term. “N” is an integer of 2 or more. “K” is a variable representing an integer from 0 to n.
Figure JPOXMLDOC01-appb-M000013
Figure JPOXMLDOC01-appb-M000013
　フィッティング処理部２４は、次の式（１１）に示される「Ｊ」の関数を最小化させる「ｃｋ」を求めることによって、フィッティングを行う。 The fitting processing unit 24 performs fitting by finding " kk " that minimizes the function of "J" shown in the following equation (11).
Figure JPOXMLDOC01-appb-M000014
Figure JPOXMLDOC01-appb-M000014
　フィッティング処理部２４は、最小化させる変数である「ｃｋ」が線形となることから、公知の最小二乗法によって「ｃｋ」を求めることができる。フィッティング処理部２４には、多項式の最高次数である「ｎ」の値があらかじめ設定される。「ｎ」の値は、ユーザによる入力操作によって設定されても良い。ＮＣ装置１は、仮モデルによるフィッティングに基づいた補正と多項式によるフィッティングによる補正との選択を可能とすることで、機械誤差の高精度な補正を行い得る。 Since the variable "c k " to be minimized is linear, the fitting processing unit 24 can obtain "c k " by a known least squares method. The value of "n", which is the highest degree of the polynomial, is preset in the fitting processing unit 24. The value of "n" may be set by an input operation by the user. The NC device 1 can perform highly accurate correction of mechanical error by enabling selection between correction based on fitting by a tentative model and correction by fitting by a polynomial.
　フィッティング処理部２４は、多項式である誤差モデルに正則化項を付加しても良い。フィッティング処理部２４は、上記の式（１１）に正則化項を付加することによって、次の式（１２）を得ることができる。フィッティング処理部２４は、式（１２）に示される「Ｊ」の関数を最小化させる「ｃｋ」を求めることによって、フィッティングを行う。 The fitting processing unit 24 may add a regularization term to the error model which is a polynomial. The fitting processing unit 24 can obtain the following equation (12) by adding a regularization term to the above equation (11). The fitting processing unit 24 performs fitting by finding " kk " that minimizes the function of "J" shown in the equation (12).
Figure JPOXMLDOC01-appb-M000015
Figure JPOXMLDOC01-appb-M000015
　上記の式（１２）において、「λ」は、正則化パラメータとする。フィッティング処理部２４には、あらかじめ「λ」の値が設定される。「λ」の値は、ユーザによる入力操作によって設定されても良い。上記の「ｎ」の値が大きくなるにしたがって生じ得るオーバーフィッティングは、多項式の各係数が過大となることによって発生する。正則化項の付加は、各係数が過大となることを防ぐ効果がある。 In the above equation (12), "λ" is a regularization parameter. The value of "λ" is set in advance in the fitting processing unit 24. The value of "λ" may be set by an input operation by the user. Overfitting, which can occur as the value of "n" increases, occurs when each coefficient of the polynomial becomes excessive. The addition of the regularization term has the effect of preventing each coefficient from becoming excessive.
　フィッティング処理部２４は、正則化項の付加によって、オーバーフィッティングを効果的に抑制することができる。これにより、フィッティング処理部２４は、汎用性が高い誤差モデルを得ることができる。 The fitting processing unit 24 can effectively suppress overfitting by adding a regularization term. As a result, the fitting processing unit 24 can obtain a highly versatile error model.
　次に、補間処理部２５による補間処理について説明する。補間処理部２５は、測定データ｛（θｉ，ｚｉ）；ｉ＝１，・・・，ｍ｝のスプライン補間を行う。補間処理部２５には、スプライン補間に用いられる多項式の次数があらかじめ設定される。補間処理部２５には、任意の次数を設定することができる。次数は、ユーザによる入力操作によって設定されても良い。補間処理部２５は、スプライン補間によって得られた補間データを誤差データ格納部１７へ出力する。 Next, the interpolation processing by the interpolation processing unit 25 will be described. The interpolation processing unit 25 performs spline interpolation of the measurement data {(θ i , z i ); i = 1, ..., M}. The degree of the polynomial used for spline interpolation is preset in the interpolation processing unit 25. An arbitrary order can be set in the interpolation processing unit 25. The order may be set by an input operation by the user. The interpolation processing unit 25 outputs the interpolation data obtained by spline interpolation to the error data storage unit 17.
　ＮＣ装置１は、フィッティング処理部２４によって求めた誤差モデルが実際の誤差から外れたものとなる場合、または、仮モデルの設定が困難である場合において、測定データのスプライン補間によってピッチ誤差補正を行うことができる。ＮＣ装置１は、上記の誤差モデルに基づいた補正とスプライン補間に基づいた補正との選択を可能とすることで、機械誤差の高精度な補正を行い得る。 The NC device 1 corrects the pitch error by spline interpolation of the measurement data when the error model obtained by the fitting processing unit 24 deviates from the actual error or when it is difficult to set the temporary model. be able to. The NC device 1 can perform highly accurate correction of mechanical error by enabling selection between correction based on the above error model and correction based on spline interpolation.
　このように、ＮＣ装置１は、フィッティング処理部２４によって求めた上記の誤差モデルに基づいた補正と、補間処理部２５による上記のスプライン補間に基づいた補正との一方を選択して、ピッチ誤差補正を行い得る。ＮＣ装置１は、ユーザによる入力部１４への入力操作にしたがって、誤差モデルに基づいた補正とスプライン補間に基づいた補正とを選択することができる。 In this way, the NC device 1 selects one of the correction based on the above error model obtained by the fitting processing unit 24 and the correction based on the above spline interpolation by the interpolation processing unit 25, and corrects the pitch error. Can be done. The NC device 1 can select a correction based on the error model and a correction based on the spline interpolation according to the input operation to the input unit 14 by the user.
　ＮＣ装置１は、誤差モデルに基づいた補正について、仮モデルのフィッティングによって求めた誤差モデルである第１の誤差モデルと、多項式のフィッティングによって求めた誤差モデルである第２の誤差モデルとの一方を選択可能とする。ＮＣ装置１は、ユーザによる入力部１４への入力操作にしたがって、誤差モデルに基づいた補正について、第１の誤差モデルに基づいた補正と第２の誤差モデルに基づいた補正とを選択することができる。 Regarding the correction based on the error model, the NC device 1 selects one of the first error model, which is an error model obtained by fitting the tentative model, and the second error model, which is the error model obtained by fitting the polynomial model. Make it selectable. The NC device 1 can select a correction based on the first error model and a correction based on the second error model for the correction based on the error model according to the input operation to the input unit 14 by the user. it can.
　補間処理部２５は、スプライン補間とは別に、測定データの直線補間を行い得るものであっても良い。この場合、ＮＣ装置１は、補間処理の結果に基づいた補正について、スプライン補間と直線補間との一方を選択可能とする。ＮＣ装置１は、ユーザによる入力部１４への入力操作にしたがって、スプライン補間に基づいた補正と直線補間に基づいた補正とを選択することができる。 The interpolation processing unit 25 may be capable of performing linear interpolation of measurement data separately from spline interpolation. In this case, the NC apparatus 1 can select either spline interpolation or linear interpolation for the correction based on the result of the interpolation processing. The NC device 1 can select a correction based on spline interpolation and a correction based on linear interpolation according to an input operation to the input unit 14 by the user.
　以上により、ＮＣ装置１は、第１の誤差モデルに基づいた補正と、第２の誤差モデルに基づいた補正と、スプライン補間に基づいた補正と、直線補間に基づいた補正とから任意の補正を選択して、芯振れ誤差補正を行うことができる。 As described above, the NC device 1 performs arbitrary correction from the correction based on the first error model, the correction based on the second error model, the correction based on spline interpolation, and the correction based on linear interpolation. You can select and correct the runout error.
　図８は、図１に示すＮＣ装置１が有する表示部２０に表示される画面の例を示す図である。図８において、「直線補間」は、上記の直線補間に基づいた補正形式を表す。「スプライン補間」は、上記のスプライン補間に基づいた補正形式を表す。「多項式フィッティング」は、上記の第２の誤差モデルに基づいた補正形式を表す。「仮モデルフィッティング」は、上記の第１の誤差モデルに基づいた補正形式を表す。ユーザは、表示部２０の画面に表示された内容を参照して、各補正形式のうちの１つを入力部１４の操作によって指定する。 FIG. 8 is a diagram showing an example of a screen displayed on the display unit 20 included in the NC device 1 shown in FIG. In FIG. 8, "linear interpolation" represents a correction format based on the above linear interpolation. "Spline interpolation" represents a correction format based on the above spline interpolation. "Polynomial fitting" represents a correction form based on the above second error model. “Temporary model fitting” represents a correction format based on the above-mentioned first error model. The user refers to the content displayed on the screen of the display unit 20 and specifies one of the correction formats by the operation of the input unit 14.
　芯振れ誤差処理部２１は、入力操作に応じた信号を入力部１４から受けると、指定された補正を行うための誤差データを誤差データ格納部１７へ出力する。「直線補間」が指定された場合、誤差データ格納部１７には、誤差データとして、補間処理部２５による直線補間の結果である補間データが格納される。「スプライン補間」が指定された場合、誤差データ格納部１７には、誤差データとして、補間処理部２５によるスプライン補間の結果である補間データが格納される。 When the run-out error processing unit 21 receives a signal corresponding to the input operation from the input unit 14, it outputs error data for performing the specified correction to the error data storage unit 17. When "linear interpolation" is specified, the error data storage unit 17 stores the interpolation data as the error data, which is the result of linear interpolation by the interpolation processing unit 25. When "spline interpolation" is specified, the error data storage unit 17 stores the interpolation data as the error data, which is the result of spline interpolation by the interpolation processing unit 25.
　「多項式フィッティング」が指定された場合、誤差データ格納部１７には、誤差データとして、第２の誤差モデルが格納される。「仮モデルフィッティング」が指定された場合、誤差データ格納部１７には、誤差データとして、第１の誤差モデルが格納される。補正量決定部１６は、誤差データ格納部１７から読み出された誤差データを基に、芯振れ誤差補正のための補正量を決定する。これにより、ＮＣ装置１は、任意の補正を選択して、芯振れ誤差補正を行う。さらに、「多項式フィッティング」が指定された場合、ＮＣ装置１は、ユーザによる入力によって、正則化項の付加の有無を決定しても良い。 When "polynomial fitting" is specified, the error data storage unit 17 stores a second error model as error data. When "temporary model fitting" is specified, the error data storage unit 17 stores the first error model as error data. The correction amount determination unit 16 determines the correction amount for the run-out error correction based on the error data read from the error data storage unit 17. As a result, the NC device 1 selects an arbitrary correction and corrects the runout error. Further, when "polynomial fitting" is specified, the NC device 1 may determine whether or not the regularization term is added by input by the user.
　表示部２０は、測定データと、誤差モデルに基づいた補正量のデータとをフィッティング処理部２４から取得して、測定データと補正量のデータとを表示しても良い。補正量のデータは、誤差データの符号反転によって得られる。また、表示部２０は、測定データと、補間処理に基づいた補正量のデータとを補間処理部２５から取得して、測定データと補正量のデータとを表示しても良い。これにより、ユーザは、測定された誤差に対する補正の効果を補正形式ごとに確認することができる。 The display unit 20 may acquire the measurement data and the correction amount data based on the error model from the fitting processing unit 24, and display the measurement data and the correction amount data. The correction amount data is obtained by sign inversion of the error data. Further, the display unit 20 may acquire the measurement data and the correction amount data based on the interpolation processing from the interpolation processing unit 25 and display the measurement data and the correction amount data. As a result, the user can confirm the effect of the correction on the measured error for each correction format.
　ＮＣ装置１は、第２の誤差モデルに基づいた誤差量について、多項式の最高次数である「ｎ」の値を変化させる入力操作に伴って、画面に表示される誤差量の値を変化させることとしても良い。これにより、ユーザは、誤差量を確認しながら「ｎ」の値を調整することができる。また、ＮＣ装置１は、正則化項が付加された第２の誤差モデルについて、正則化パラメータである「λ」の値を変化させる入力操作に伴って、画面に表示される誤差量の値を変化させることとしても良い。これにより、ユーザは、誤差量を確認しながら「λ」の値を調整することができる。 The NC device 1 changes the value of the error amount displayed on the screen with respect to the error amount based on the second error model in accordance with the input operation of changing the value of "n" which is the highest degree of the polynomial. May be. As a result, the user can adjust the value of "n" while checking the amount of error. In addition, the NC device 1 sets the value of the amount of error displayed on the screen of the second error model to which the regularization term is added as the input operation changes the value of the regularization parameter “λ”. It may be changed. As a result, the user can adjust the value of "λ" while checking the amount of error.
　ＮＣ装置１は、主軸４について、芯振れ誤差補正を行った場合における指令角度と芯振れ誤差補正を行わなかった場合における指令角度とのサンプリングを行うこととしても良い。ユーザは、かかるサンプリングの結果を基に双方の指令角度の差分を確認することによって、芯振れ誤差補正による改善の効果を判断することができる。ユーザは、芯振れ誤差補正を行った場合における回転角度と芯振れ誤差補正を行わなかった場合における回転角度とを測定機器によって測定し、測定結果を基に双方の回転角度を確認しても良い。 The NC device 1 may sample the command angle when the runout error is corrected and the command angle when the runout error is not corrected for the spindle 4. The user can judge the effect of the improvement by the run-out error correction by confirming the difference between the two command angles based on the sampling result. The user may measure the rotation angle when the runout error is corrected and the rotation angle when the runout error is not corrected by a measuring device, and confirm both rotation angles based on the measurement result. ..
　次に、ＮＣ装置１のハードウェア構成について説明する。図１に示すＮＣ装置１の各機能部は、実施の形態１にかかる数値制御方法を実行するためのプログラムである数値制御プログラムがハードウェアを用いて実行されることによって実現される。 Next, the hardware configuration of the NC device 1 will be described. Each functional unit of the NC device 1 shown in FIG. 1 is realized by executing a numerical control program, which is a program for executing the numerical control method according to the first embodiment, by using hardware.
　図９は、本発明の実施の形態１にかかるＮＣ装置１のハードウェア構成を示すブロック図である。ＮＣ装置１は、各種処理を実行するＣＰＵ（Central　Processing　Unit）６１と、データ格納領域を含むＲＡＭ（Random　Access　Memory）６２と、不揮発性メモリであるＲＯＭ（Read　Only　Memory）６３と、外部記憶装置６４とを有する。また、ＮＣ装置１は、ＮＣ装置１への情報の入力のための入力インタフェース６５と、入力操作を受け付ける入力デバイス６６と、画面において情報を表示するディスプレイ６７とを有する。図９に示す各部は、バス６８を介して相互に接続されている。 FIG. 9 is a block diagram showing a hardware configuration of the NC device 1 according to the first embodiment of the present invention. The NC device 1 includes a CPU (Central Processing Unit) 61 that executes various processes, a RAM (Random Access Memory) 62 that includes a data storage area, a ROM (Read Only Memory) 63 that is a non-volatile memory, and an external storage device. Has 64 and. Further, the NC device 1 has an input interface 65 for inputting information to the NC device 1, an input device 66 for receiving an input operation, and a display 67 for displaying information on the screen. The parts shown in FIG. 9 are connected to each other via a bus 68.
　ＣＰＵ６１は、ＲＯＭ６３および外部記憶装置６４に記憶されているプログラムを実行する。図１に示すプログラム取得部１０、プログラム解析部１１、軸指令生成部１２、データ処理部１５、補正量決定部１６、加算器１８および駆動指令部１９の各機能は、ＣＰＵ６１を使用して実現される。外部記憶装置６４は、ＨＤＤ（Hard　Disk　Drive）あるいはＳＳＤ（Solid　State　Drive）である。外部記憶装置６４は、数値制御プログラムと、各種情報とを記憶する。図１に示す誤差データ格納部１７の機能は、外部記憶装置６４を使用して実現される。 The CPU 61 executes a program stored in the ROM 63 and the external storage device 64. The functions of the program acquisition unit 10, the program analysis unit 11, the axis command generation unit 12, the data processing unit 15, the correction amount determination unit 16, the adder 18, and the drive command unit 19 shown in FIG. 1 are realized by using the CPU 61. Will be done. The external storage device 64 is an HDD (Hard Disk Drive) or an SSD (Solid State Drive). The external storage device 64 stores the numerical control program and various information. The function of the error data storage unit 17 shown in FIG. 1 is realized by using the external storage device 64.
　ＲＯＭ６３には、ＮＣ装置１であるコンピュータまたはコントローラの基本となる制御のためのプログラムであるＢＩＯＳ（Basic　Input/Output　System）あるいはＵＥＦＩ（Unified　Extensible　Firmware　Interface）といったブートローダであって、ハードウェアを制御するソフトウェアまたはプログラムが記憶されている。なお、数値制御プログラムは、ＲＯＭ６３に記憶されても良い。 The ROM 63 is a boot loader such as a BIOS (Basic Input / Output System) or UEFI (Unified Extensible Firmware Interface), which is a program for basic control of a computer or controller which is an NC device 1, and controls hardware. The software or program is stored. The numerical control program may be stored in the ROM 63.
　ＲＯＭ６３および外部記憶装置６４に記憶されているプログラムは、ＲＡＭ６２にロードされる。ＣＰＵ６１は、ＲＡＭ６２に数値制御プログラムを展開して各種処理を実行する。入力インタフェース６５は、ＮＣ装置１の外部の装置との接続インタフェースである。図１に示すデータ取得部１３の機能は、入力インタフェース６５を使用して実現される。 The program stored in the ROM 63 and the external storage device 64 is loaded into the RAM 62. The CPU 61 develops a numerical control program in the RAM 62 and executes various processes. The input interface 65 is a connection interface with an external device of the NC device 1. The function of the data acquisition unit 13 shown in FIG. 1 is realized by using the input interface 65.
　入力デバイス６６は、キーボードあるいはポインティングデバイスといった、情報入力のためのデバイスである。図１に示す入力部１４の機能は、入力デバイス６６を使用して実現される。ディスプレイ６７は、液晶ディスプレイあるいは有機ＥＬディスプレイといった表示装置である。図１に示す表示部２０の機能は、ディスプレイ６７を使用して実現される。 The input device 66 is a device for inputting information, such as a keyboard or a pointing device. The function of the input unit 14 shown in FIG. 1 is realized by using the input device 66. The display 67 is a display device such as a liquid crystal display or an organic EL display. The function of the display unit 20 shown in FIG. 1 is realized by using the display 67.
　数値制御プログラムは、コンピュータによる読み取りが可能とされた記憶媒体に記憶されたものであっても良い。ＮＣ装置１は、記憶媒体に記憶された数値制御プログラムを外部記憶装置６４へ格納しても良い。記憶媒体は、フレキシブルディスクである可搬型記憶媒体、あるいは半導体メモリであるフラッシュメモリであっても良い。数値制御プログラムは、他のコンピュータあるいはサーバ装置から通信ネットワークを介して、ＮＣ装置１となるコンピュータあるいはコントローラへインストールされても良い。 The numerical control program may be stored in a storage medium that can be read by a computer. The NC device 1 may store the numerical control program stored in the storage medium in the external storage device 64. The storage medium may be a portable storage medium that is a flexible disk, or a flash memory that is a semiconductor memory. The numerical control program may be installed from another computer or server device to the computer or controller that becomes the NC device 1 via the communication network.
　ＮＣ装置１の機能は、専用のハードウェアである処理回路によって実現されても良い。処理回路は、単一回路、複合回路、プログラム化されたプロセッサ、並列プログラム化したプロセッサ、ＡＳＩＣ（Application　Specific　Integrated　Circuit）、ＦＰＧＡ（Field-Programmable　Gate　Array）、又はこれらの組み合わせである。ＮＣ装置１の機能は、一部を専用のハードウェアで実現し、他の一部をソフトウェアまたはファームウェアで実現するようにしても良い。 The function of the NC device 1 may be realized by a processing circuit which is dedicated hardware. The processing circuit is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Some of the functions of the NC device 1 may be realized by dedicated hardware, and some of the functions may be realized by software or firmware.
　ＮＣ装置１は、工作機械２の外部の装置に限られず、工作機械２に含まれるものであっても良い。ＮＣ装置１の各機能部は、１つの装置に集約されたものに限られず、複数の装置に分散されたものであっても良い。ＮＣ装置１は、１つの装置を用いて実現されるものであっても良く、複数の装置を用いて実現されるものであっても良い。なお、ＮＣ装置１による芯振れ誤差補正の手法は、工作機械２以外の産業用機械の制御に適用されても良い。 The NC device 1 is not limited to an external device of the machine tool 2, and may be included in the machine tool 2. Each functional unit of the NC device 1 is not limited to one integrated in one device, and may be distributed in a plurality of devices. The NC device 1 may be realized by using one device, or may be realized by using a plurality of devices. The method of correcting the runout error by the NC device 1 may be applied to the control of an industrial machine other than the machine tool 2.
　実施の形態１によると、ＮＣ装置１は、機構に生じ得る現象を表すモデル関数を求めることによって、機構が持つ構造を考慮した仮モデルを設定して、測定データにモデル関数をフィッティングさせる。ＮＣ装置１は、仮モデルのフィッティングによって、機械誤差の高精度な補正を行うことができる。ＮＣ装置１は、分割点の数を多くすることによる補正精度の向上を図る場合と比べて、誤差の測定に要する負担を少なくすることができる。ＮＣ装置１は、仮モデルのフィッティングに基づいた補正と、多項式のフィッティングに基づいた補正と、スプライン補間に基づいた補正との選択を可能とすることで、機械誤差の高精度な補正を行い得る。以上により、ＮＣ装置１は、回転軸の位置がずれることに起因する機械誤差の高精度な補正が可能となるという効果を奏する。 According to the first embodiment, the NC device 1 sets a tentative model in consideration of the structure of the mechanism by obtaining a model function representing a phenomenon that can occur in the mechanism, and fits the model function to the measurement data. The NC device 1 can correct the mechanical error with high accuracy by fitting the temporary model. The NC device 1 can reduce the burden required for measuring the error as compared with the case where the correction accuracy is improved by increasing the number of division points. The NC device 1 can perform highly accurate correction of mechanical error by making it possible to select between correction based on the fitting of the tentative model, correction based on the fitting of the polynomial, and correction based on spline interpolation. .. As described above, the NC device 1 has an effect that it is possible to correct the mechanical error caused by the displacement of the rotation axis with high accuracy.
　本実施の形態１では、主軸４の芯振れ誤差を補正する場合について説明したが、主軸４以外の駆動軸が回転する場合の芯振れ誤差の補正においても本実施の形態１が適用できることは言うまでもない。 In the first embodiment, the case of correcting the runout error of the spindle 4 has been described, but it goes without saying that the first embodiment can be applied to the correction of the runout error when the drive shafts other than the spindle 4 rotate. No.
　以上の実施の形態に示した構成は、本発明の内容の一例を示すものであり、別の公知の技術と組み合わせることも可能であるし、本発明の要旨を逸脱しない範囲で、構成の一部を省略、変更することも可能である。 The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.
　１　ＮＣ装置、２　工作機械、３　直線駆動軸、４　主軸、５　ワーク、１０　プログラム取得部、１１　プログラム解析部、１２　軸指令生成部、１３　データ取得部、１４　入力部、１５　データ処理部、１６　補正量決定部、１７　誤差データ格納部、１８　加算器、１９　駆動指令部、２０　表示部、２１　芯振れ誤差処理部、２２　周期誤差処理部、２３　仮モデル設定部、２４　フィッティング処理部、２５　補間処理部、３１　サーボアンプ、３２　サーボモータ、３３　ボールねじ、３４　移動体、３５　主軸アンプ、３６　主軸モータ、３７　シャフト、３８　チャック、４０　位置検出器、４１　発光ダイオード、４２　固定スリット、４３　フォトダイオード、４４　回転盤、４５　Ａ相スリット、４６　Ｂ相スリット、４７，４８　歯、５１，５２，５３　円、６１　ＣＰＵ、６２　ＲＡＭ、６３　ＲＯＭ、６４　外部記憶装置、６５　入力インタフェース、６６　入力デバイス、６７　ディスプレイ、６８　バス。 1 NC device, 2 machine machine, 3 linear drive shaft, 4 spindle, 5 work, 10 program acquisition unit, 11 program analysis unit, 12 axis command generation unit, 13 data acquisition unit, 14 input unit, 15 data processing unit, 16 Correction amount determination unit, 17 error data storage unit, 18 adder, 19 drive command unit, 20 display unit, 21 runout error processing unit, 22 periodic error processing unit, 23 temporary model setting unit, 24 fitting processing unit, 25 interpolation Processing unit, 31 servo amplifier, 32 servo motor, 33 ball screw, 34 moving body, 35 spindle amplifier, 36 spindle motor, 37 shaft, 38 chuck, 40 position detector, 41 light emitting diode, 42 fixed slit, 43 photodiode, 44 turntable, 45 A-phase slit, 46 B-phase slit, 47, 48 teeth, 51, 52, 53 yen, 61 CPU, 62 RAM, 63 ROM, 64 external storage device, 65 input interface, 66 input device, 67 display , 68 bus.

Claims (9)

  1. 　工具を用いてワークを加工する工作機械において前記工具または前記ワークを回転動作させる機構の駆動源であるモータを制御する数値制御装置であって、
    　前記機構が有する回転軸の位置がずれる現象である芯振れを表すモデル関数を求めることによって、前記芯振れによる機械誤差の仮モデルを設定する仮モデル設定部と、
    　前記機構の動作を測定した結果である測定データに前記モデル関数をフィッティングさせることによって前記機械誤差のモデルである誤差モデルを求めるフィッティング処理部と、
    　前記誤差モデルに基づいて前記モータへの指令を補正する補正部と、
    　を備えることを特徴とする数値制御装置。     A numerical control device that controls a motor that is a drive source of the tool or a mechanism for rotating the work in a machine tool that processes a work using a tool.
    A temporary model setting unit that sets a temporary model of mechanical error due to the center runout by obtaining a model function representing the runout, which is a phenomenon in which the position of the rotation axis of the mechanism shifts.
    A fitting processing unit that obtains an error model that is a model of the mechanical error by fitting the model function to the measurement data that is the result of measuring the operation of the mechanism.
    A correction unit that corrects commands to the motor based on the error model,
    A numerical control device characterized by comprising.
  2. 　前記測定データのスプライン補間を行う補間処理部を備え、
    　前記補正部は、前記誤差モデルに基づいた補正と前記スプライン補間に基づいた補正とのうち選択された一方を行うことを特徴とする請求項１に記載の数値制御装置。     It is provided with an interpolation processing unit that performs spline interpolation of the measurement data.
    The numerical control device according to claim 1, wherein the correction unit performs one of a correction based on the error model and a correction based on the spline interpolation.
  3. 　前記フィッティング処理部は、前記誤差モデルである第１の誤差モデルを求め、かつ、前記測定データに多項式をフィッティングさせることによって第２の誤差モデルを求め、
    　前記補正部は、前記第１の誤差モデルに基づいた補正と前記第２の誤差モデルに基づいた補正とのうち選択された一方を行うことを特徴とする請求項１に記載の数値制御装置。     The fitting processing unit obtains a first error model, which is the error model, and obtains a second error model by fitting a polynomial to the measurement data.
    The numerical control device according to claim 1, wherein the correction unit performs one of a correction based on the first error model and a correction based on the second error model.
  4. 　前記フィッティング処理部は、正則化項が付加された前記多項式を前記測定データにフィッティングさせることによって前記第２の誤差モデルを求めることを特徴とする請求項３に記載の数値制御装置。 The numerical control device according to claim 3, wherein the fitting processing unit obtains the second error model by fitting the polynomial to which a regularization term is added to the measurement data.
  5. 　前記測定データと、前記誤差モデルに基づいた補正量のデータとを表示する表示部を備えることを特徴とする請求項１から４のいずれか１つに記載の数値制御装置。 The numerical control device according to any one of claims 1 to 4, further comprising a display unit for displaying the measurement data and the correction amount data based on the error model.
  6. 　前記モデル関数の周期は、前記回転軸の回転周期と同期していることを特徴とする請求項１から５のいずれか１つに記載の数値制御装置。 The numerical control device according to any one of claims 1 to 5, wherein the period of the model function is synchronized with the period of rotation of the rotation axis.
  7. 　前記回転軸に取り付けられている回転盤について、互いに垂直な２つの軸である第１の軸と第２の軸との原点に、前記芯振れが生じていないときにおける前記回転盤の中心点が一致するとして、
    　前記回転盤の半径をＰ、および前記芯振れによって移動した前記中心点と前記原点との距離をｄとして、Ｐ／ｄ＝Ｐ’が成り立ち、前記芯振れによって移動した前記中心点と前記原点とを結ぶ線分と前記第１の軸とがなす角度をθとして、前記原点を基準とする前記中心点の方角を示す角度の前記芯振れによる変化量をθ＋φと表し、かつ、前記機械誤差をαとした場合において、
    　前記モデル関数は、以下の式（１）によって表されることを特徴とする請求項１から６のいずれか１つに記載の数値制御装置。
    Figure JPOXMLDOC01-appb-M000001
         With respect to the rotary disk attached to the rotary axis, the center point of the rotary disk when the runout does not occur is at the origin of the first axis and the second axis, which are two axes perpendicular to each other. As a match
    P / d = P'is established, where P is the radius of the turntable and d is the distance between the center point moved by the runout and the origin, and the center point moved by the runout and the origin are The angle formed by the line segment connecting the above and the first axis is θ, the amount of change in the angle indicating the direction of the center point with respect to the origin due to the runout is θ + φ, and the mechanical error is expressed as θ + φ. In the case of α
    The numerical control device according to any one of claims 1 to 6, wherein the model function is represented by the following equation (1).
    Figure JPOXMLDOC01-appb-M000001
  8. 　ｎを２以上の整数として、前記フィッティング処理部は、前記誤差モデルをｎ次多項式と仮定し、
    　ｍを２以上の整数、ｋを０からｎの整数を表す変数として、前記回転軸が回転する角度範囲をｍ個に分割した場合における分割点の１つであるｉ番目のポイントについて、指令に応じた回転角度である指令角度をθｉ、測定された誤差をｚｉとし、かつ、θを変数とする前記ｎ次多項式をｆ（θ）、前記ｎ次多項式におけるｋ次の項の係数をｃｋとした場合において、
    　前記フィッティング処理部は、次の式（２）によって表されるＪを最小化させるｃｋを求めることによって、測定された誤差に前記ｎ次多項式をフィッティングさせることを特徴とする請求項１から７のいずれか１つに記載の数値制御装置。
    Figure JPOXMLDOC01-appb-M000002
         Let n be an integer of 2 or more, and the fitting processing unit assumes that the error model is an nth-order polynomial.
    As a variable representing m as an integer of 2 or more and k as an integer from 0 to n, the command is given for the i-th point, which is one of the division points when the angle range in which the rotation axis rotates is divided into m pieces. The command angle, which is the corresponding rotation angle, is θ i , the measured error is z i , the nth-order polynomial with θ as a variable is f (θ), and the coefficient of the k-th order term in the n-th order polynomial is In the case of kk
    Claims 1 to 7 are characterized in that the fitting processing unit fits the nth-order polynomial to the measured error by obtaining a ck that minimizes J represented by the following equation (2). The numerical control device according to any one of.
    Figure JPOXMLDOC01-appb-M000002
  9. 　ｎを２以上の整数として、前記フィッティング処理部は、前記誤差モデルをｎ次多項式と仮定し、
    　ｍを２以上の整数、ｋを０からｎの整数として、前記回転軸が回転する角度範囲をｍ個に分割した場合における分割点の１つであるｉ番目のポイントについて、指令に応じた回転角度である指令角度をθｉ、測定された誤差をｚｉとし、かつ、θを変数とする前記ｎ次多項式をｆ（θ）、前記ｎ次多項式におけるｋ次の項の係数をｃｋ、正則化パラメータをλとした場合において、
    　前記フィッティング処理部は、次の式（３）によって表されるＪを最小化させるｃｋを求めることによって、測定された誤差に前記ｎ次多項式をフィッティングさせることを特徴とする請求項８に記載の数値制御装置。
    Figure JPOXMLDOC01-appb-M000003
         Let n be an integer of 2 or more, and the fitting processing unit assumes that the error model is an nth-order polynomial.
    When m is an integer of 2 or more and k is an integer of 0 to n, the i-th point, which is one of the division points when the angle range in which the rotation axis rotates is divided into m pieces, is rotated according to a command. a command angle is the angle theta i, the measured error and z i, and the n-th order polynomial for the theta variable f (theta), the coefficient of k-th order term in the polynomial of degree n c k, When the regularization parameter is λ,
    The eighth aspect of the present invention is characterized in that the fitting processing unit fits the nth-order polynomial to the measured error by obtaining a ck that minimizes J represented by the following equation (3). Numerical control device.
    Figure JPOXMLDOC01-appb-M000003
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