JP2013214231A - Motor controller, motor control system, and cutting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve surface accuracy of a cutting surface even when a rotary tool is fed at higher speed.SOLUTION: A cutting device 1 includes a rotary tool 6 to cut a workpiece, a main shaft motor 14 to rotationally drive the rotary tool 6, X-, Y-, Z-axis motors 11, 12, 13 to drive feed shafts of X-, Y-, Z-axes of the rotary tool 6, respectively, X-, Y-, Z-axis motor controllers 21, 22, 23 to control the X-, Y-, Z-axis motors 11, 12, 13, respectively, and a host controller 100 to output a positional command to the X-, Y-, Z-axis motor controllers 21,22,23, respectively. The X-axis motor controller 21 to control the X-axis motor includes a sine wave generation part 35 that adds a sine wave torque correction command of a cycle T to the torque command calculated with an internal control operation to correct the torque command. The sine wave generation part 35 adds the sine wave torque correction command of the sine wave shape of the cycle T, an amplitude A, and a reference phase φ to the torque command.

Description

  Embodiments disclosed herein relate to a motor control device, a motor control system, and a cutting apparatus.

  Patent Document 1 describes a control device for an NC machine tool that changes the rotation speed of the main shaft and the feed speed of the feed shaft while keeping the ratio between the rotation speed of the main shaft and the feed speed of the feed shaft constant.

JP 11-129144 A

  Patent Document 1 can reduce chatter vibration caused by a natural frequency of a mechanical system (cutting system). However, in the cutting process, in addition to the chatter vibration, there is a phenomenon in which uneven waves having a predetermined cycle are formed on the cutting surface when the rotary tool is fed at a feed rate equal to or higher than a certain speed. When surface processing of a workpiece is performed by such cutting, a scale-like uneven pattern is formed on the entire surface, which is not suitable for precision processing that requires high surface accuracy. When the feed speed is sufficiently low, the formation of such a scale-like uneven pattern can be avoided, but the process time required for the surface processing becomes long. Since this uneven pattern cannot be avoided even if the rotational speed of the rotary tool is changed, the above-described prior art cannot solve such a problem.

  The present invention has been made in view of such problems, and a motor control device and a motor control system that can be used for cutting that can improve the surface accuracy of the cutting surface even when the rotary tool is fed at a high feed rate. And it aims at providing a cutting device.

  In order to solve the above-described problem, according to one aspect of the present invention, a motor control device that controls a motor includes at least one of a position command input from a host device and a torque command calculated by a predetermined internal control calculation. A motor control device including a correction unit that adds a correction value of a predetermined period and corrects a command is applied.

  According to the present invention, even when the rotary tool is fed at a high feed rate, the surface accuracy of the cutting surface can be improved.

It is the figure which looked at the whole appearance of the cutting device provided with the motor control device and motor control system concerning one embodiment from the front. It is a block diagram showing typically the system configuration of a cutting device. It is a figure which shows the uneven | corrugated wave formed in the workpiece | work surface. It is the block diagram which showed the structure of the internal control calculation of a X-axis motor control apparatus. It is a figure which shows the relationship between the sine wave state of the sine wave torque correction instruction | command in each of an X-axis motor control apparatus and a Y-axis motor control apparatus, and a sine wave parameter. It is an example of the flowchart showing the control content which CPU of a high-order control apparatus performs. It is the block diagram which showed the structure of the internal control calculation of a Z-axis motor control apparatus. It is a figure which shows the relationship between the pulse state of a rectangular alternating current position correction command in a Z-axis motor control apparatus, and a rectangular alternating current parameter.

  Hereinafter, a first embodiment will be described with reference to the drawings.

  Drawing 1 is a figure which looked at the whole appearance of the cutting device provided with the motor control device and motor control system concerning one embodiment from the front. In the example shown in FIG. 1, a cutting device 1 that is a cutting device is an NC cutting device having a so-called portal structure, and mainly for a workpiece (not shown) that is a workpiece. Milling is performed.

  The cutting apparatus 1 generally includes a base 2, a first header 3, a second header 4, and a work table 5.

  The base 2 is configured in a substantially gate shape integrally provided with two columns 2a erected side by side on the left and right sides and a horizontal beam 2b that passes over the upper ends thereof. An X-axis motor 11 is provided at one end of the upper horizontal beam 2b, and an X-axis ball screw 2c provided on the output shaft is installed over almost the entire length of the horizontal beam 2b. Two X-axis rails 2d are provided along the upper and lower edges of the front surface of the horizontal beam 2b.

  The first header 3 is a substantially rectangular member that is long upward. The first header 3 is suspended on the two X-axis rails 2d of the base 2 on the back side, and is screwed into the X-axis ball screw 2c. Thus, the first header 3 can be reciprocated in the X-axis direction (left-right direction in the figure) by forward / reverse drive of the X-axis motor 11. The first header 3 is provided with a Z-axis motor 13 at its upper end, and a Z-axis ball screw (not shown) provided on the output shaft is installed in the vertical direction. Two Z-axis rails 3 a are provided along the left and right edges of the front surface of the first header 3.

  The second header 4 is a substantially rectangular member having substantially the same lateral width as that of the first header 3 and is suspended on the two Z-axis rails 3a of the first header 3 on the back side thereof, and also has a Z-axis ball screw. Are screwed together. Accordingly, the second header 4 can be reciprocated in the Z-axis direction (vertical direction in the figure) by forward / reverse driving of the Z-axis motor 13. A spindle motor 14 is provided on the lower side of the front surface of the second header 4 via a holder bracket 4a. The rotary tool 6 is fixed to the spindle 4b together with the spindle 4b provided on the output shaft. Can be rotated around the vertical axis, that is, around the Z axis.

  The work table 5 is fixed between the lower ends of the two columns 2a of the base 2, and has a base 5a positioned below and a work table 5b positioned above. A base 5a fixed between the two columns 2a is provided with a Y-axis motor 12 on the front side, and a Y-axis ball screw (not shown) provided on the output shaft is installed in the front-rear direction. Yes. Two Y-axis rails (not shown) are provided along the left and right edges of the upper surface of the base 5a. The work table 5b is a rectangular member having a width substantially the same as that of the base 5a. The work table 5b is mounted on the two Y-axis rails of the base 5a on the lower surface side and is screwed into a Y-axis ball screw. Thereby, the work table 5b can be reciprocated in the Y-axis direction (the front-rear direction in the figure) by the forward / reverse drive of the Y-axis motor 12.

  The cutting apparatus 1 configured as described above reciprocally moves the rotary tool 6 rotated by the spindle motor 14 in the three-axis directions of the XYZ axes with respect to the work fixed on the work table 5b. Can do. The X-axis motor 11, the Y-axis motor 12, and the Z-axis motor 13 correspond to the motors described in each claim, and the main shaft motor 14 corresponds to the tool rotation motor described in each claim.

  FIG. 2 is a block diagram schematically showing the system configuration of the cutting apparatus 1. In the example shown in FIG. 2, the cutting apparatus 1 includes a host control device 100, an X axis motor control device 21, an X axis motor 11, a Y axis motor control device 22, a Y axis motor 12, and a Z axis. The motor control device 23, the Z-axis motor 13, the main shaft motor control device 24, the main shaft motor 14, and four encoders 25, 26, 27, and 28 provided corresponding to the respective motors.

  The host control device 100 is configured by a computer such as a general-purpose personal computer, PLC (Programmable Logic Controller), or motion controller, and has a function of controlling the entire cutting device 1. In particular, the host controller 100 outputs a position command to each of the X-axis motor controller 21, the Y-axis motor controller 22, and the Z-axis motor controller 23 to each of the motor controllers 21, 22, and 23. The rotational positions of the corresponding X-axis motor 11, Y-axis motor 12, and Z-axis motor 13 are controlled. In the example of the present embodiment, the host control device 100 also outputs a cycle correction command (to be described later) to the X-axis motor control device 21 and the Y-axis motor control device 22 together. The host controller 100 also controls the spindle motor controller 24 to rotate the spindle motor 14 directly connected to the rotary tool 6 at a predetermined rotational speed based on the motor position information from the encoder 28 provided in the spindle motor 14. The speed command is output to. The host control device 100 corresponds to a host device described in each claim.

  The X-axis motor control device 21, the Y-axis motor control device 22, and the Z-axis motor control device 23 are provided in the respective motors 11, 12, 13 corresponding to the position commands input from the host control device 100, respectively. Based on the motor position information from the encoders 25, 26, 27, currents corresponding to the torque commands calculated by the respective internal control calculations are output, and the rotational driving of the motors 11, 12, 13 corresponding to each is controlled. It has a function. As a result, the motor control devices 21, 22, and 23 control the rotation positions of the corresponding motors 11, 12, and 13 to be the rotation positions corresponding to the position command input from the host control device 100. Moreover, each motor control device 21, 22, 23 can also control the rotational speed of each motor 11, 12, 13 by controlling the rotational position at a sufficiently short time interval. The internal control calculation in each motor control device 21, 22, 23 will be described in detail later. The X-axis motor control device 21, the Y-axis motor control device 22, and the Z-axis motor control device 23 correspond to the motor control devices described in the claims.

  The main shaft motor control device 24 has a function of outputting an alternating current corresponding to the speed command input from the host control device 100 and controlling the rotational drive of the main shaft motor 14 composed of, for example, an induction motor.

  In the cutting apparatus 1 having the above configuration, in cutting using the rotary tool 6, particularly milling using a ball end mill or the like, feed control is performed with three axes XYZ while the rotary tool 6 is rotated. By doing so, the workpiece is processed into an arbitrary shape. In this milling, for example, as shown in FIG. 3, the ball end mill 6 </ b> A is perpendicular to the rotation axis while maintaining the state in which the ball end mill 6 </ b> A is cut in the axial direction (Z-axis direction) with a predetermined cut amount. When it is fed in a horizontal direction (direction parallel to the surface of the workpiece: the X-axis direction in the figure) at a feed rate of a certain level or more, irregularities with regular intervals (constant period) are formed on the surface portion cut at the end of the ball end mill 6A. Waves are formed. This is because the cutting blade on the outer peripheral side surface of the ball end mill 6A cuts on the side surface with respect to the feed direction, but the cutting blade cuts intermittently (periodically) on the side surface, so This is due to the intermittent influence on the end cutting.

  When surface processing of the workpiece W is performed by such cutting, a scale-like uneven pattern is formed on the entire surface, which is not suitable for precision processing that requires high surface accuracy. When the feed speed is sufficiently low, the formation of such a scale-like uneven pattern can be avoided, but the process time required for the surface processing becomes long.

  On the other hand, in the present embodiment, the X-axis motor control device 21 and the Y-axis motor control device 22 that control the rotational positions or rotational speeds of the X-axis motor 11 and the Y-axis motor 12 perform their internal control calculations. The command is corrected by adding a correction value of a predetermined period to the calculated torque command. By performing such command correction, the X-axis motor control device 21 and the Y-axis motor control device 22 can flexibly suppress the influence of intermittent (periodic) disturbance at the end of the ball end mill 6A. .

  FIG. 4 is a block diagram showing the configuration of the internal control calculation of the X-axis motor control device 21 in the present embodiment. The configuration of the internal control calculation of the Y-axis motor control device 22 is also the same, and illustration is omitted. In the example of the present embodiment, each unit is configured by software, but each may be configured by hardware.

  In FIG. 4, the X-axis motor control device 21 includes a position control unit 31, a speed control unit 32, a speed conversion unit 33, a current control unit 34, and a sine wave generation unit 35.

  The position control unit 31 outputs a speed command so as to reduce this position deviation based on the position deviation between the position command input from the host controller 100 and the motor position information detected by the encoder 25.

  Based on the speed deviation between the speed command input from the position control unit 31 and the motor speed information input from the speed conversion unit 33 described later, the speed control unit 32 issues a torque command so as to reduce this speed deviation. Output.

  The speed conversion unit 33 calculates and outputs motor speed information corresponding to the rotation speed of the X-axis motor based on the change in the motor position information detected by the encoder 25. Specifically, a differentiator may be used for the speed converter 33.

  The current control unit 34 outputs, for example, a drive current by PWM control to the X-axis motor 11 based on the torque command input from the speed control unit 32.

  From the above configuration, the internal control calculation of the X-axis motor control device 21 generally has a double loop configuration of a speed control system feedback loop and a position control system feedback loop. Although not shown, since the feedback loop control of the current control system is also performed inside the current control unit 34, the internal control calculation of the X-axis motor control device 21 has a substantially triple loop configuration. Have. In the present embodiment, in addition to the configuration of the internal control calculation of the general motor control device, the sine wave torque correction command generated by the sine wave generation unit 35 is added to the torque command output from the speed control unit 32. And input to the current controller 34.

  The sine wave generation unit 35 generates and outputs a sine wave torque correction command based on the sine wave parameter included in the cycle correction command input from the host controller 100. Further, the cycle correction command input from the host controller 100 includes a switching command for instructing the sine wave generation unit 35 to output and stop the sine wave torque correction command. When the sine wave torque correction command is added to the torque command, the torque command input to the current control unit 34 is corrected in a substantially pulsating manner (not shown). The sine wave torque correction command corresponds to a correction value of a predetermined period described in each claim, and the sine wave generation unit 35 corresponds to a correction unit described in each claim.

  In the sine wave torque correction command, the state of the sine wave is defined by each parameter of the sine wave parameter. FIG. 5 is a diagram illustrating the relationship between the sine wave state of the sine wave torque correction command and the sine wave parameter in each of the X-axis motor control device 21 and the Y-axis motor control device 22.

Here, there are generally three elements that define the state of the sine wave: period, amplitude, and phase. Correspondingly, the sine wave parameters of the cycle correction command output from the host controller 100 to the XY-axis motor controllers 21 and 22 include three parameters of the cycle T, the amplitude A, and the phase φ. ing. In the example of this embodiment, among these three parameters, the period T and the amplitude A are set to the same value common to both the X-axis motor control device 21 and the Y-axis motor control device 22, and the phase φ is set to the X-axis. The reference phase φ _X0 in the motor control device 21 and the reference phase φ _Y0 in the Y-axis motor control device 22 are set to different values.

  The period T is a parameter that is uniformly set based on the configuration and control contents on the cutting device 1 side. Specifically, the rotation speed of the rotary tool 6 and the number of cutting blades included in the rotary tool 6 are set. As described above with reference to FIG. 3, the pitch of the uneven wave formed when the surface of the workpiece W is cut at the end of the rotary tool 6 such as the ball end mill 6 </ b> A (for example, the convex vertex interval) is It has been found by the inventors of the present application that it depends on three conditions: the surface feed speed, the rotational speed of the rotary tool 6, and the number of cutting blades provided in the rotary tool 6.

  For example, assuming that the feed speed of the rotary tool 6 in the X-axis direction is constant, the greater the rotational speed of the rotary tool 6, the narrower the pitch of the uneven waves formed. In addition, the pitch of the uneven waves formed becomes wider as the feed speed increases with the rotational speed kept constant. Even when the feed speed and the rotation speed are the same, the pitch of the uneven waves formed becomes narrower as the number of cutting blades of the rotary tool 6 increases. As described above, this is because the cutting blade cuts intermittently (periodically) on the side surface of the rotary tool 6 that is fed in the horizontal direction, so that the end cutting in the rotation axis direction is also intermittent. It is because of having an influence.

  Thus, in order to suppress the intermittent influence in the end cutting that is the cause of the formation of the uneven wave, the rotary tool 6 may be pressed and moved at the same cycle as the intermittent influence. The period of intermittent influence is the same as the period at which each cutting blade cuts the workpiece on the side surface of the rotary tool 6 during feed movement, and this is the rotational speed of the rotary tool 6 and the cutting blade included in the rotary tool 6. Inversely proportional to the product of numbers. Thereby, the period T of the sine wave parameter is set by the host controller 100 so as to be inversely proportional to the product of the rotational speed of the rotary tool 6 and the number of cutting blades.

  The amplitude A is a parameter that is appropriately adjusted and set in accordance with not only the shape of the rotary tool 6 and the control content thereof but also the combination of the material of the work to be used and the type of coolant.

  The phase φ is also a parameter that is appropriately adjusted and set according to a combination of the shape and control content of the rotary tool 6, the workpiece material, the type of coolant, and the like. In the example of this embodiment, the entire XY horizontal surface of the workpiece is processed by repeating the reciprocating movement of the X-axis direction feed and the predetermined width feed in the Y-axis direction between them, but the sine wave torque correction command Correction is performed only during feed movement in the X-axis direction. That is, the host control device 100 outputs a position command to the X-axis motor control device 21 and simultaneously corrects the torque command with a sine wave torque correction command for both the X-axis motor control device 21 and the Y-axis motor control device 22. The switching command to be started is output. The reference phase φ of each axis defines the phase difference of the sine wave torque correction command when such a switching command is input, and the phase is expressed in time in the illustrated example. The correction by the sine wave torque correction command may be always corrected as well as during the X-axis direction feed movement.

As described above, the phase φ is a parameter that differs between the X axis and the Y axis, and the difference between the X axis reference phase φ _X0 and the Y axis reference phase φ _Y0 is the inter-axis phase difference φ. _XY . In the example of this embodiment, it has set this axial phase difference _XY phi 1 time 4 minutes period T, that is, 90 degrees angle conversion. As a result, during the feed movement of the rotary tool 6 in the X-axis direction, a pressing force for rotating the rotary tool 6 in a perfect circle around the rotation axis of the rotary tool 6 is applied. Thereby, the intermittent influence in the edge part cutting of the rotary tool 6 can be suppressed, and formation of the uneven wave on the cutting surface can be reduced.

The period T corresponds to the predetermined period described in each claim, the amplitude A corresponds to the predetermined amplitude described in each claim, and the reference phases φ _X0 and φ _Y0 correspond to the predetermined period described in each claim. corresponds to the reference phase, the phase difference _XY phi between the axes corresponding to a predetermined phase difference in each claim.

  FIG. 6 is an example of a flowchart showing control contents executed by a CPU (not shown) of the host control device 100 in order to realize the cutting control of the present embodiment described above. Before executing this flow, a predetermined rotary tool 6 is fixed to the spindle 4b in advance, and the reference position (for example, the position of the tip of the central axis) of the rotary tool 6 is located at the origin position in the XYZ axis space. Assuming that.

  First, in step S5, the rotation speed of the rotary tool 6 is set according to conditions such as the diameter and type of the rotary tool 6 and the material of the workpiece.

  Proceeding to step S10, the cutting amount in the Z-axis direction (see FIG. 3), the feed width in the Y-axis direction, the feed length and the feed speed in the X-axis direction are set according to the shape of the workpiece. Note that, in the setting of the control amount in step S5 and step S10, it may be automatically set with a value calculated by the host controller 100 according to various conditions given in advance, or in particular illustrated. You may set with the value arbitrarily input by the user via the operation input part. Further, the feed width in the Y-axis direction and the feed length in the X-axis direction are determined in advance by the machining program and may not be arbitrarily set by the user.

Proceeding to step S15, the sine wave parameters (cycle T, amplitude A, reference phase φ _X0 , φ _Y0 ) of the sine wave torque correction command are set according to the control amount and various conditions set in steps S5 and S10. . Of these, the period T is automatically set according to the rotation speed set in step S5 and the number of cutting blades provided in the rotary tool 6 to be used, and the amplitude A and the reference phases φ _X0 and φ _Y0 are automatically set. It may be set or may be arbitrarily set by the user. Then, the corresponding sine wave parameters are output to the X-axis motor control device 21 and the Y-axis motor control device 22 (the switching command remains as a correction stop command).

  Proceeding to step S20, a speed command corresponding to the rotational speed set in step S5 is output to the spindle motor control device 24, and rotation of the rotary tool 6 is started. From then on until step S60 described later, the rotational speed of the rotary tool 6 is maintained based on the motor position information from the encoder 28 provided in the spindle motor 14.

  In step S25, the rotary tool 6 is fed and moved in the X-axis direction and the Y-axis direction to the first cutting position in the XY plane for alignment.

  The process proceeds to step S30, and the rotary tool 6 is fed and moved in the Z-axis direction so as to cut the workpiece up to the Z-axis direction cut amount set in step S10.

  Proceeding to step S35, a position command corresponding to the feed length in the X-axis direction set in step S10 is output to the X-axis motor control device 21, and the feed movement of the rotary tool 6 in the X-axis direction is started. The feed is moved at the feed speed in the X-axis direction set in. While the X-axis direction feed movement is being performed, the switching tool for instructing the X-axis motor control device 21 and the Y-axis motor control device 22 to always execute the correction of the torque command is continuously output, and the rotary tool 6 is applied with a pressing force for rotating in a perfect circle around the rotation axis at a period T.

  It moves to step S40 and it is determined whether all the cutting with respect to the workpiece | work was complete | finished. If the cutting has not been completed yet, the determination is not satisfied and the routine goes to Step S45.

  In step S45, the rotary tool 6 is fed and moved in the Y-axis direction with the Y-axis direction feed width set in step S10. And it returns to said step S35 and repeats the same procedure. In addition, the feed movement of the rotary tool 6 in the X-axis direction in step S35 repeats reciprocation.

  On the other hand, in the determination in step S40, when all the cutting operations on the workpiece have been completed, the determination is satisfied, and the process proceeds to step S50.

  In step S50, the rotary tool 6 is fed and moved away from the workpiece in the direction opposite to that in step S30.

  In step S55, the rotary tool 6 is fed and moved in the X-axis direction and the Y-axis direction to the origin position in the XY plane.

  In step S60, the output of the speed command to the spindle motor control device 24 is stopped, and the rotation of the rotary tool 6 is stopped. Then, this flow ends.

  In the above, each of the configurations including the X-axis motor control device 21, the Y-axis motor control device 22, the Z-axis motor control device 23, the X-axis motor 11, the Y-axis motor 12, the Z-axis motor 13, and the host control device 100. This corresponds to the motor control system described in the claims. Moreover, the structure which combined the rotary tool 6, the spindle motor 14, and said motor control system corresponds to the cutting apparatus of each claim.

  As described above, the cutting device 1 according to the present embodiment, the three XYZ axis motor control devices 21, 22, 23, and the three XYZ axis motor control devices 21, 22, 23, and 3 included in the cutting device 1 are provided. According to the system comprising the two XYZ-axis motors 11, 12, 13 and the host controller 100, the sine wave generator 35 calculates a correction value of a predetermined period, that is, a sine wave to the torque command calculated by the internal control calculation in the motor controller. Add the torque correction command and correct the command. The motor control device can flexibly suppress the influence of intermittent (periodic) disturbance by performing such command correction. By applying such a motor control device to the cutting device 1 that performs the above-described milling, the sine wave parameters (period T, amplitude A, and reference phase φ) of the sine wave torque correction command are appropriately set. By setting, the intermittent influence in the end cutting in the rotation axis direction due to the intermittent (periodic) cutting by the cutting blade on the side surface of the rotary tool 6 can be removed. As a result, even when the rotary tool 6 is fed at a high feed rate, the surface accuracy of the cutting surface can be improved.

  In the present embodiment, the host controller 100 sequentially outputs a period correction command including a sine wave parameter so that the sine wave state of the sine wave torque command to be output to the sine wave generation unit 35 can be controlled in real time. However, the present invention is not limited to this. For example, predetermined sine wave parameters are fixedly set in advance in the sine wave generation unit 35, and the host control device 100 performs period correction only on the output and stop switching of the sine wave torque correction command to the sine wave generation unit 35. You may make it command with a command.

  Further, according to the present embodiment, the sine wave generation unit 35 adds a sine wave sine wave torque correction command to the torque command. When the XY-axis motor control devices 21 and 22 perform such command correction, the influence of intermittent (periodic) disturbance can be flexibly suppressed.

  Further, according to the present embodiment, the sine wave generation unit 35 adds the sine wave torque correction command having the period T, the amplitude A, and the reference phase φ to the torque command. By applying the XY-axis motor control devices 21 and 22 to the cutting device 1 that performs the above-described milling, the cutting amount is always downward (direction perpendicular to the surface of the workpiece) with respect to the rotary tool 6. Can be maintained at a constant level, and the intermittent effects in the end cutting in the direction of the rotation axis can be removed with high accuracy.

  According to the present embodiment, the period T of the sine wave parameter is set to a value that is inversely proportional to the product of the number of cutting blades of the rotary tool 6 and the rotational speed. The intermittent effect of the end cutting in the rotation axis direction due to intermittent (periodic) cutting by the cutting blade on the side surface of the rotary tool 6 is the product of the number of cutting blades of the rotary tool 6 and the rotational speed. Synchronize inversely with. Therefore, the sine wave generation unit 35 corrects the command with a period T having a value inversely proportional to the product of the number of blades of the rotary tool 6 and the rotation speed, so that the intermittent influence can be removed functionally.

In addition, according to the present embodiment, the sine wave generation unit 35 of the X-axis motor control device 21 or the Y-axis motor control device 22 causes the X-axis and Y-axis to have an inter-axis phase difference φ _XY with respect to the torque command. The sine wave torque correction command having the same period T is added to correct the command. Thus, intermittent (periodic) cutting by the cutting blade on the side surface of the rotary tool 6 is performed by correcting the torque with the sine wave torque correction command of the period T in the XY axis direction, that is, the direction parallel to the surface of the workpiece. It is possible to remove the intermittent influence due to the end cutting in the direction of the rotation axis due to the above, and to indirectly remove the uneven wave formed on the surface portion cut at the end of the rotary tool 6. Further, by the sine-wave torque correction command in the X-axis and Y-axis have the relationship of the same period T in mutually axis-to-axis phase difference phi _XY, X-T of the rotary tool 6 feeding of XY axes is coordinated The feed can be corrected so that the position on the plane is rotated in an elliptical shape, and the intermittent influence in the end cutting in the rotation axis direction can be removed functionally.

Further, according to this embodiment, the sine wave generator 35 instruction correction with a phase difference phi _XY between 90 ° axis. Thereby, the feed correction of each axis of XY can be performed so that the rotary tool 6 is rotated in a perfect circle in cooperation with each other, and the intermittent influence in the end cutting in the rotation axis direction can be removed functionally.

In addition, as described above, the period T and the amplitude A of the sine wave torque correction commands are the same between the _XY axes, and the unevenness formed on the workpiece surface is not limited to setting the inter-axis phase difference φ _XY to 90 degrees. period T in accordance with the shape of the wave, the axial phase difference _XY phi or to different amplitude a suitably may be appropriately adjusted to other than 90 degrees. Such adjustment of the sine wave parameter may be made manually by the user, or according to the shape of the corrugated wave detected by the contact with the probe contact provided in the cutting apparatus 1 or the camera image. May be adjusted automatically.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and technical idea of the present invention. Hereinafter, such modifications will be described in order.

(1) When correcting the position command in the Z-axis direction with the rectangular alternating current correction value during the surface feed movement In the above embodiment, the XY-axis torque command is sinusoidal during the X-axis direction feed movement of the rotary tool 6. However, the present invention is not limited to this. For example, by correcting the position command in the Z-axis direction with the rectangular alternating-current correction value during the feed movement of the rotary tool 6 in the X-axis direction, the formation of uneven waves on the workpiece surface can be suppressed.

  FIG. 7 corresponding to FIG. 4 is a block diagram showing the configuration of the internal control calculation of the Z-axis motor control device 23 in this modification. In the case of this modification, in the system configuration shown in FIG. 2, the host controller 100 also inputs a period correction command together with the position command to the Z-axis motor control device 23 (not shown).

  In FIG. 7, the internal control calculation of the Z-axis motor control device 23 also has a general double loop configuration (triple loop configuration). In this modified example, in addition to the configuration of the internal control calculation of the general motor control device, a rectangular AC position correction command generated by the rectangular AC generation unit 36 is further added to the position command input from the host control device 100. Are added to the position control unit 31.

  The rectangular AC generation unit 36 generates and outputs a pulsed rectangular AC position correction command based on the rectangular AC parameter included in the cycle correction command input from the host controller 100. Further, the cycle correction command input from the host controller 100 includes a switching command for instructing the rectangular AC generation unit 36 to output and stop the rectangular AC position correction command. When the pulse-shaped rectangular AC position correction command is added to the position command, the position command input to the position control unit 31 is corrected to a substantially rectangular pulsating flow (not shown). The rectangular AC position correction command corresponds to a correction value of a predetermined period described in each claim, and the rectangular AC generation unit 36 corresponds to a correction unit described in each claim.

  In the rectangular AC correction command, the state of the pulse is defined by each parameter of the rectangular AC parameter. FIG. 8 is a diagram illustrating the relationship between the pulse state of the rectangular AC position correction command and the rectangular AC parameter in the Z-axis motor control device 23.

Here, the rectangular alternating current refers to a discrete alternating waveform that alternately generates positive and negative pulses having the same absolute value every half period of a predetermined period. Correspondingly, the rectangular AC parameter of the cycle correction command output from the host controller 100 to the Z-axis motor controller 23 includes three parameters of cycle T, amplitude A, and reference phase _φZ0 . These period T, amplitude A, and reference phase _φZ0 may be set equal to those in the above embodiment. By adding the rectangular AC position correction command to the position command and correcting the command, the cutting amount of the rotary tool 6 periodically changes during the feed movement of the rotary tool 6 in the X-axis direction. Thereby, the intermittent influence in the edge part cutting of the rotary tool 6 can be suppressed, and formation of the uneven wave on the cutting surface can be reduced. The reference phase _φZ0 corresponds to a predetermined reference phase described in each claim.

  As described above, according to the present modification, the rectangular AC generation unit 36 adds a pulse-shaped correction value to the position command. When the Z-axis motor control device 23 performs such command correction, the influence of intermittent (periodic) disturbance can be flexibly suppressed. For example, when the position command has a pulse train configuration or the encoder 27 outputs a pulse train, the correction value may be corrected with the pulse train correction value accordingly.

  Further, according to the present modification, the rectangular alternating-current generator 36 alternately adds the same absolute value positive value and negative value pulse-like correction value to the position command every half cycle of the period T. The command can be corrected by a rectangular AC position correction command having a rectangular AC shape at the period T. By applying the Z-axis motor control device 23 to the cutting device 1 that performs the above-described milling, the amount of cut in the downward direction (direction perpendicular to the surface of the workpiece) is always constant with respect to the rotary tool 6. Therefore, the intermittent influence in the end cutting in the rotation axis direction can be removed functionally.

  In any of the XYZ axes, the command for correcting the command is not limited to the torque command and the position command. The command correction may be performed for the speed command, and the combination of the axis and the command may be arbitrarily set. . The sinusoidal correction value is not limited to the torque command, and may be applied as a correction value for other commands, and the pulse-shaped correction value may be applied to other than the position command. Moreover, you may correct | amend with respect to several instruction | command simultaneously. Further, cooperative correction may be made with any combination of XYZ axes.

  In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 Cutting apparatus 2 Base 3 1st header 4 2nd header 5 Work stand 6 Rotating tool 6A Ball end mill 11 X-axis motor (motor, motor control system)
12 Y-axis motor (motor, motor control system)
13 Z-axis motor (motor, motor control system)
14 Spindle motor (tool rotation motor)
21 X-axis motor control device (motor control device, motor control system)
22 Y-axis motor control device (motor control device, motor control system)
23 Z-axis motor control device (motor control device, motor control system)
24 Spindle motor controller 25, 26, 27, 28 Encoder 31 Position controller 32 Speed controller 33 Speed converter 34 Current controller 35 Sine wave generator 36 Rectangular AC generator 100 Host controller (host device, motor control system) )
W Workpiece (Workpiece)
T period (predetermined period)
A Amplitude (predetermined amplitude)
φ phase φ _X0 , φ _Y0 , φ _Z0 reference phase (predetermined reference phase)
φ _XY axis phase difference

In order to solve the above problems, according to one aspect of the present invention, three motors that respectively drive the feed axes of the X-axis, the Y-axis, and the Z-axis of the rotary tool, and the motor based on a position command are provided. A motor control system for controlling each of the motor control systems, wherein the motor control device is configured to cut the rotary tool during the feed operation of at least one of the X axis and the Y axis. a motor control system comprising a correction unit for commanding the correction by adding the correction value of the predetermined period to a command and at least one of the torque command is calculated by a predetermined internal control operation is applied.

Claims (9)

A motor control device for controlling a motor,
A motor control device comprising: a correction unit for correcting a command by adding a correction value of a predetermined cycle to at least one of a position command input from a host device and a torque command calculated by a predetermined internal control calculation.   The motor control device according to claim 1, wherein the correction unit adds the pulse-shaped correction value to the position command and the sinusoidal correction value to the torque command.   The correction unit alternately adds the positive correction value of the same absolute value and the negative correction value of the pulse value every half cycle of the predetermined period to the position command. The motor control apparatus described.   4. The motor according to claim 1, wherein the correction unit adds the sine wave correction value of the predetermined period, a predetermined amplitude, and a predetermined reference phase to the torque command. 5. Control device. Three motors that respectively drive the feed axes of the X-axis, Y-axis, and Z-axis of the rotary tool;
Three motor control devices according to any one of claims 1 to 4, which respectively control the motors;
The host device that outputs the position command to the motor control device;
A motor control system comprising:   6. The motor control system according to claim 5, wherein the predetermined period is set as a value that is inversely proportional to the product of the number of blades and the rotation speed of the rotary tool.   The correction unit of the motor control device that controls the motor of at least one of the feed axes of the X axis and the Y axis is configured such that the X axis and the Y axis are the same with a predetermined phase difference with respect to the torque command. 7. The motor control system according to claim 5, wherein the command correction is performed by adding a correction value of a sine wave having a predetermined period.   The motor control system according to claim 7, wherein the correction unit corrects the command with the predetermined phase difference of 90 degrees. The rotary tool for cutting a workpiece;
A tool rotation motor for rotationally driving the rotary tool;
The motor control system according to any one of claims 5 to 8,
A cutting apparatus characterized by comprising:

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