JP2020154956A - Numerical control device and machine tool - Google Patents

Abstract

To provide a numerical control device and a machine tool capable of accurately stopping a drive shaft at a specified rotational position.SOLUTION: A numerical control device includes a CPU. The CPU starts the clamping of a drive shaft by a clamping device when the drive shaft connected to a C-shaft table moves to a specified rotational position by driving of a C-shaft motor. The CPU determines whether a misalignment amount is equal to or less than an error threshold when clamping of the drive shaft by the clamping device is completed. The CPU unclamps the drive shaft from the clamping device (S61) and controls clamping thereafter (S81) when it is determined that the misalignment amount is larger than the error threshold. Therefore, the numerical control device can accurately stop the drive shaft at a designated rotational position.SELECTED DRAWING: Figure 6

Description

The present invention relates to numerical control devices and machine tools.

Patent Document 1 discloses a numerical control device that controls a machine tool having a C axis as a rotation axis and an A axis as an inclination axis. The C-axis is an axis that holds and rotates the work to be machined. The A axis is an axis that changes the inclination of the C axis. The machine tool includes a work holding mechanism that holds the work rotatably. The work holding mechanism includes an A-axis table. The A-axis table is rotatably provided. The A-axis motor rotates a support shaft connected to the A-axis table. The A-axis table rotates integrally with the support shaft and tilts in any direction. The numerical control device adjusts the tilt angle of the A-axis table by controlling the rotation direction and the amount of rotation of the output shaft of the A-axis motor.

Japanese Unexamined Patent Publication No. 2016-086550

The machine tool may be provided with a clamping device for clamping the rotated support shaft and suppressing the support shaft from rotating beyond a predetermined rotation amount. When the clamping device clamps the support shaft, the support shaft may rotate slightly. When the amount of rotation of the support shaft is large, it may affect the machining accuracy of the workpiece.

An object of the present invention is to provide a numerical control device and a machine tool capable of accurately stopping a drive shaft at a designated rotation position.

The numerical control device according to the first aspect of the present invention is a numerical control device capable of controlling a machine tool including a servomotor, a drive shaft that is rotationally driven by the servomotor, and a clamp portion that clamps the drive shaft. A first control unit that controls the motor and rotates the drive shaft to the first rotation position, which is a designated rotation position, and a clamp when the drive shaft is rotated to the first rotation position by the first control unit. The second control unit that controls the unit and clamps the drive shaft, the determination unit that determines the relationship between the deviation amount, which is the difference between the rotation position of the drive shaft and the first rotation position, and the threshold value, and the above. When the determination unit determines that the amount of deviation after the clamping of the drive shaft by the second control unit is completed is equal to or greater than a predetermined first threshold value, the clamp unit is controlled to unclamp the drive shaft. After that, it is characterized by including a third control unit that controls the clamp unit and clamps the drive shaft.

According to the first aspect, the numerical control device can accurately stop the drive shaft at a designated rotation position.

In the first aspect, the third control unit may control the clamp unit to clamp the drive shaft when the first time elapses after the unclamping of the drive shaft is completed. The numerical control device can secure the time for the first control unit to control the drive unit after unclamping the drive shaft. Therefore, the numerical control device can accurately stop the drive shaft at a designated rotation position.

In the first aspect, the third control unit further unclamps and clamps the drive shaft until the amount of deviation after controlling the clamp unit and clamping the drive shaft becomes less than the first threshold value. When the first number of times, which is the number of times of the repeat control by the third control unit, is equal to or greater than a predetermined second threshold value, the repeat control by the third control unit is stopped. It may be provided with a stop portion. The user can easily determine the malfunction of the control of the numerical control device based on the first number of times.

In the first aspect, when the determination unit determines that the deviation amount after the clamp of the drive shaft by the second control unit is completed is equal to or greater than the third threshold value having a value larger than the first threshold value, notification is given. The unit may be notified. Therefore, the user can easily grasp the malfunction of the control of the numerical control device.

In the first aspect, when the determination unit determines that the deviation amount after the clamp of the drive shaft by the third control unit is completed is equal to or greater than the fourth threshold value having a value larger than the first threshold value, the above-mentioned A second stop unit may be further provided to stop the repetitive control by the third control unit and notify the notification unit. Therefore, the user can easily grasp the malfunction of the control of the numerical control device.

In the first aspect, when the determination unit determines that the deviation amount is equal to or greater than the first threshold value, a third stop unit for stopping the driving of the servomotor until the second time elapses is further provided. When the second time elapses, the third control unit may control the clamp unit to clamp the drive shaft. When the deviation amount is equal to or greater than the first threshold value, the numerical control device stops the driving of the servomotor for the second time, so that the torque generated in the drive shaft is reduced. Therefore, the numerical control device can suppress an increase in the amount of deviation of the drive shaft.

In the first aspect, a detection unit capable of detecting the rotation position is provided, and the determination unit includes the deviation amount which is the difference between the rotation position detected by the detection unit and the first rotation position, and the threshold value. It may be judged by the relation of. Since the numerical control device can detect the rotation position of the drive shaft, the drive shaft can be accurately stopped at the designated rotation position.

The machine tool according to the second aspect of the present invention is characterized by including the numerical control device according to the first aspect. According to the second aspect, the same effect as that of the first aspect can be obtained.

A perspective view of the machine tool 100. The perspective view of the work support device 8. The electric block diagram of the numerical control device 1 and the machine tool 100. The flow chart of the C-axis alignment process. It is a flow chart of the C-axis alignment process, and is a continuation of FIG. It is a flow chart of the C-axis alignment process, and is a continuation of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, up / down, left / right, front / back, which are indicated by arrows in the figure, are used. The horizontal direction, the front-rear direction, and the vertical direction of the machine tool 100 are the X-axis direction, the Y-axis direction, and the Z-axis direction of the machine tool 100, respectively. The machine tool 100 shown in FIG. 1 is a five-axis controlled vertical machine tool having a moving axis, a rotating axis, and an inclined axis. The moving axes are the X-axis, the Y-axis, and the Z-axis. The rotation axis is the C axis and the tilt axis is the A axis.

The structure of the machine tool 100 will be described with reference to FIG. The machine tool 100 includes a base 2, a column 5, a Y-axis moving mechanism (not shown), an X-axis moving mechanism (not shown), a Z-axis moving mechanism (not shown), a spindle head 6, a spindle (not shown), and a work. It includes a support device 8, a tool change device 9, a control box (not shown), and the like.

The base 2 includes a stand 11, a spindle base 12, a right work base 13, a left work base 14, and the like. The gantry 11 is a substantially rectangular parallelepiped structure that is long in the front-rear direction. The spindle base 12 is formed in a substantially rectangular parallelepiped shape long in the front-rear direction, and is provided behind the upper surface of the gantry 11. The right work base 13 is provided on the right front of the upper surface of the gantry 11. The left work base 14 is provided on the left front of the upper surface of the gantry 11. The right work base 13 and the left work base 14 each include front support bases 13A and 14A and rear support bases 13B and 14B, respectively. The support bases 13A, 13B, 14A, and 14B are each formed in a columnar shape extending in the vertical direction, and the work support device 8 is supported on the upper surface.

The Y-axis movement mechanism is provided on the upper surface of the spindle base 12, and a pair of Y-axis rails 16 (only the right Y-axis rail 16 is shown in FIG. 1), a Y-axis ball screw (not shown), and a Y-axis motor 62 (see FIG. 3). ) Etc. are provided. The pair of Y-axis rails 16 and Y-axis ball screws extend in the Y-axis direction. The pair of Y-axis rails 16 guide the moving body 15 on the upper surface in the Y-axis direction. The moving body 15 is formed in a substantially flat plate shape, and has a nut (not shown) on the outer surface of the bottom. The nut is screwed into the Y-axis ball screw. When the Y-axis motor 62 rotates the Y-axis ball screw, the moving body 15 moves along with the nut along the pair of Y-axis rails 16. Therefore, the Y-axis moving mechanism supports the moving body 15 so as to be movable in the Y-axis direction.

The X-axis moving mechanism is provided on the upper surface of the moving body 15, and includes a pair of X-axis rails (not shown), an X-axis ball screw (not shown), an X-axis motor 61 (see FIG. 3), and the like. The X-axis rail and the X-axis ball screw extend in the X-axis direction. The column 5 extends in the vertical direction and is provided on the upper surface of the moving body 15. The column 5 is provided with a nut (not shown) at the bottom. The nut is screwed into the X-axis ball screw. When the X-axis motor 61 rotates the X-axis ball screw, the column 5 moves along the pair of X-axis rails together with the nut. Therefore, the X-axis moving mechanism supports the column 5 so as to be movable in the X-axis direction. Therefore, the column 5 can be moved in the X-axis direction and the Y-axis direction on the base 2 by the Y-axis moving mechanism, the moving body 15, and the X-axis moving mechanism.

The Z-axis moving mechanism is provided on the front surface of the column 5, and includes a pair of Z-axis rails (not shown), a Z-axis ball screw (not shown), a Z-axis motor 63 (see FIG. 3), and the like. The Z-axis rail and the Z-axis ball screw extend in the Z-axis direction. The spindle head 6 is provided with a nut (not shown) on the back surface. The nut is screwed into a Z-axis ball screw. The Z-axis motor 63 is fixed to a bearing (not shown) at the upper end of the Z-axis ball screw. When the Z-axis motor 63 rotates the Z-axis ball screw, the spindle head 6 moves along the pair of Z-axis rails. Therefore, the Z-axis moving mechanism supports the spindle head 6 so as to be movable in the Z-axis direction.

The spindle head 6 is provided with a Z-axis cover 18 at the bottom. The Z-axis cover 18 covers the Z-axis moving mechanism provided on the front surface of the column 5, and expands and contracts with the vertical movement of the spindle head 6. The Z-axis cover 18 prevents chips and cutting fluid from entering the Z-axis moving mechanism. The spindle (not shown) is provided inside the spindle head 6, and a tool mounting hole (not shown) is provided in the lower part of the spindle head 6. The tool is mounted in the tool mounting hole. The spindle is rotated by a spindle motor 64 (see FIG. 3) provided above the spindle head 6.

The work support device 8 is arranged on the front side of the upper surface of the gantry 11, and is fixedly supported on the upper surfaces of the right work base 13 and the left work base 14. The work support device 8 rotatably holds the work (not shown). The work support device 8 includes an A-axis table 20 and a C-axis table 40. The A-axis table 20 can rotate about an axis parallel to the X-axis direction. The rotation axis of the A-axis table 20 is the A-axis. The C-axis table 40 is formed in a disk shape and is provided substantially in the center of the upper surface of the A-axis table 20. The C-axis table 40 is rotatable about an axis parallel to the Z-axis direction, and the work is fixed to the upper surface by using the gripping mechanism 200 (see FIG. 2). The rotation axis of the C-axis table 40 is the C-axis. The work support device 8 can tilt the A-axis table 20 in any direction. The specific structure of the work support device 8 will be described later.

The tool changing device 9 includes a tool magazine (not shown), a protective cover 9A, and the like. The protective cover 9A covers and protects the tool magazine. The tool magazine has a substantially annular shape surrounding the column 5 and the spindle head 6. The tool magazine includes a plurality of pots (not shown), a chain (not shown), a magazine motor 65 (see FIG. 3), and the like. The pot is equipped with removable tools. The chain is provided in an annular shape along the tool magazine. Multiple pots are mounted along the chain. Driven by the magazine motor 65, the chain moves along the shape of the tool magazine. Multiple pots move with the chain. The tool change position is the position of the pot located at the bottom of the tool magazine. The tool changer 9 replaces the tool held by the pot at the tool change position with the tool currently mounted on the spindle during the ascending / descending operation of the spindle head 6.

The control box is attached to, for example, the outer wall of a cover (not shown) that covers the machine tool 100. The control box stores the numerical control device 1 inside. The numerical control device 1 controls the operation of the machine tool 100 based on the NC program. The NC program is composed of a plurality of blocks, and each block contains a control command. The control command is, for example, a G code, an M code, or the like.

A specific structure of the work support device 8 will be described with reference to FIG. The work support device 8 includes an A-axis table 20, a left-side support base 27, a right-side drive mechanism unit 28, a C-axis table 40, a C-axis drive unit 50, and the like. The A-axis table 20 includes a table portion 21, a right connecting portion 22, and a left connecting portion 23. The table portion 21 is a plate-shaped portion having a substantially rectangular shape in a plan view in which the inclination angle of the A-axis table 20 is 0 ° and the upper surface is horizontal. The right connecting portion 22 extends obliquely upward to the right from the right end portion of the table portion 21 and rotatably connects with the right driving mechanism portion 28. The left connecting portion 23 extends obliquely upward to the left from the left end portion of the table portion 21 and rotatably connects to the left support base 27 described later. The C-axis table 40 is rotatably provided at substantially the center of the upper surface of the table portion 21.

The C-axis drive unit 50 is provided on the lower surface of the table unit 21. The C-axis drive unit 50 includes a drive shaft 41, a C-axis motor 66 (see FIG. 3), and a clamp device 68 (see FIG. 3) inside. One end of the drive shaft 41 is connected to the C-axis table 40 via a hole (not shown) provided in the substantially center of the table portion 21. The other end of the drive shaft 41 is connected to the output shaft of the C-axis motor 66. Therefore, the C-axis table 40 is rotated by the drive of the C-axis motor 66. The clamping device 68 includes, for example, a disc brake (not shown) and can clamp the drive shaft 41. The clamping device 68 suppresses the rotation of the drive shaft 41 by clamping the drive shaft 41. During cutting, the machine tool 100 rotates the work around the C axis to a predetermined rotation position by rotating the drive shaft 41, and the clamping device 68 clamps the drive shaft 41 to rotate the C axis of the work. Determine the position.

The left support base 27 is located on the left side of the A-axis table 20. The left support base 27 is formed in a columnar shape having a substantially triangular shape in the left side view and having a predetermined thickness in the left-right direction. The left support base 27 rotatably supports a substantially cylindrical support shaft 31 projecting to the left from the left end surface of the left connecting portion 23 at the apex portion projecting upward. The bottom of the left support base 27 is bridged and fixed to the upper surfaces of the support bases 14A and 14B (see FIG. 1) of the left work base 14.

The right side drive mechanism unit 28 is located on the right side of the A-axis table 20. The right drive mechanism portion 28 includes cover portions 33 and 34. The cover portion 33 is formed in a substantially rectangular parallelepiped shape and covers the periphery of the upper half of the right drive mechanism portion 28. The cover portion 34 is connected to the lower portion of the cover portion 33 and covers the periphery of the lower half of the right drive mechanism portion 28. The cover portions 33 and 34 house a right support base (not shown), a speed reducer (not shown), an A-axis motor 67 (see FIG. 3), and the like inside. The right support base is a substantially columnar support shaft (illustrated) that projects to the right from the right end surface of the right connecting portion 22 through a circular hole portion 35 provided straddling the left side surfaces of the cover portions 33 and 34, respectively. (Omitted) is rotatably supported, and the A-axis motor 67 is integrally held.

The support shaft of the right connecting portion 22 and the output shaft of the A-axis motor 67 are connected to each other via a speed reducer. The speed reducer is a mechanical device that reduces the rotational speed of power by a gear or the like to output the speed reducer, and can obtain a torque proportional to the reduction ratio as the output. Therefore, when the output shaft of the A-axis motor 67 rotates, the support shaft of the right connecting portion 22 decelerates and rotates from the output shaft of the A-axis motor 67 via the speed reducer. The A-axis table 20 rotates integrally with the right connecting portion 22 and tilts in an arbitrary direction around the A-axis. Therefore, the work support device 8 can tilt the work in an arbitrary direction with respect to the tool mounted on the spindle. The bottom of the right support base is bridged and fixed to the upper surfaces of the support bases 13A and 13B (see FIG. 1) of the right work base 13.

The electrical configuration of the numerical control device 1 and the machine tool 100 will be described with reference to FIG. The numerical control device 1 includes a CPU 91, a ROM 92, a RAM 93, a non-volatile memory 94, an I / O board 96, and the like. The CPU 91 controls the operation of the machine tool 100. The ROM 92 stores a control program and the like described later. The control program executes the C-axis alignment process shown in FIGS. 4 to 6. The RAM 93 stores a clamp confirmation time counter, an unclamp confirmation time counter, a clamp waiting time counter, a motor waiting time counter, a value of a variable N, etc., which are generated during execution of various processes. A description of each counter and variable N will be described later. The non-volatile memory 94 stores the NC program, the maximum number of retries, the allowable deviation value, the clamp waiting time, and the like. The maximum number of retries, the allowable deviation value, and the clamp waiting time will be described later. The I / O board 96 is a circuit board that inputs / outputs various signals to and from the machine tool 100.

The machine tool 100 further includes drive circuits 51 to 59. The drive circuits 51 to 59 are connected to the I / O board 96 of the numerical control device 1. The drive circuit 51 outputs a drive current (pulse) to the X-axis motor 61 according to a command signal of the CPU 91. The encoder 71 is connected to the X-axis motor 61 and the I / O board 96. The encoder 71 detects the position information of the X-axis motor 61 (absolute position information of the motor) and inputs the detection signal to the I / O board 96. The drive circuit 52 outputs a drive current to the Y-axis motor 62 according to a command signal of the CPU 91. The encoder 72 is connected to the Y-axis motor 62 and the I / O board 96. The encoder 72 detects the position information of the Y-axis motor 62 and inputs the detection signal to the I / O board 96.

The drive circuit 53 outputs a drive current to the Z-axis motor 63 according to a command signal of the CPU 91. The encoder 73 is connected to the Z-axis motor 63 and the I / O board 96. The encoder 73 detects the position information of the Z-axis motor 63 and inputs the detection signal to the I / O board 96. The drive circuit 54 outputs a drive current to the spindle motor 64 according to a command signal of the CPU 91. The encoder 74 is connected to the spindle motor 64 and the I / O board 96. The encoder 74 detects the position information of the spindle motor 64 and inputs the detection signal to the I / O board 96. The drive circuit 55 outputs a drive current to the magazine motor 65 according to a command signal of the CPU 91. The encoder 75 is connected to the magazine motor 65 and the I / O board 96. The encoder 75 detects the position information of the magazine motor 65 and inputs the detection signal to the I / O board 96.

The drive circuit 56 outputs a drive current to the C-axis motor 66 according to a command signal of the CPU 91. The encoder 76 is connected to the C-axis motor 66 and the I / O board 96. The encoder 76 detects the position information of the C-axis motor 66 and inputs the detection signal to the I / O board 96. The drive circuit 57 outputs a drive current to the A-axis motor 67 according to a command signal of the CPU 91. The encoder 77 is connected to the A-axis motor 67 and the I / O board 96. The encoder 77 detects the position information of the A-axis motor 67 and inputs the detection signal to the I / O board 96.

The drive circuit 58 outputs a drive current to the clamp device 68 according to a command signal of the CPU 91.
The command signal that the CPU 91 inputs to the drive circuit 58 via the I / O board 96 is an unclamp output signal. When the CPU 91 inputs the unclamp output signal to the drive circuit 58, the clamping device 68 unclamps the drive shaft 41. When the CPU 91 does not input the unclamp output signal to the drive circuit 58, the clamp device 68 clamps the drive shaft 41. Hereinafter, the fact that the CPU 91 inputs the unclamp output signal to the drive circuit 58 is referred to as "turning on the unclamp output signal", and the fact that the CPU 91 does not input the unclamp output signal to the drive circuit 58 is referred to as "the unclamp output signal is input". It is called "OFF".

The drive circuit 59 outputs a drive current to the display unit 84 according to a command signal of the CPU 91. The input unit 81 is connected to the I / O board 96. The input unit 81 and the display unit 84 are attached to, for example, the outer wall of a cover (not shown) that covers the machine tool 100. The display unit 84 is, for example, an LCD. The user operates the input unit 81 while checking the information displayed by the display unit 84 to store the NC program, the maximum number of retries, the allowable deviation value, the clamp waiting time, and the like in the non-volatile memory 94.

The X-axis motor 61, the Y-axis motor 62, the Z-axis motor 63, the spindle motor 64, the magazine motor 65, the C-axis motor 66, and the A-axis motor 67 are all servo motors. Encoders 71 to 77 are general absolute encoders. Encoders 71 to 75 and 77 are position sensors that detect and output the absolute position of the rotation position of the output shaft of the servo motor. The encoder 76 is a position sensor that detects and outputs the absolute position of the rotation position of the drive shaft 41. The drive circuits 51 to 57 receive feedback signals from the encoders 71 to 77 and perform feedback control of position and speed. The drive circuits 51 to 59 may be, for example, an FPGA circuit.

The C-axis alignment process executed by the CPU 91 will be described with reference to FIGS. 4 to 6. When the CPU 91 receives the control command for rotating the C-axis table 40, the CPU 91 executes the C-axis alignment process.

As shown in FIG. 4, the CPU 91 acquires the maximum number of retries from the non-volatile memory 94 (S1), acquires the allowable deviation value (S2), and acquires the clamp waiting time (S3). The CPU 91 sets the variable N to 0 (S4). The variable N is the number of times the retry process described later is executed.

The CPU 91 drives the C-axis motor 66 (S11). By driving the C-axis motor 66, the drive shaft 41 and the C-axis table 40 connected to the drive shaft 41 rotate. The CPU 91 determines whether the drive shaft 41 has reached a predetermined rotation position set by the user (S12). The CPU 91 determines S12 based on the detection result of the encoder 76. When the CPU 91 determines that the drive shaft 41 has not reached the predetermined rotation position (S12: NO), the processing is returned to S12, and the processing is repeated.

When the CPU 91 determines that the drive shaft 41 has reached the predetermined rotation position (S12: YES), the CPU 91 turns off the unclamp output signal (S21). At this time, the clamping device 68 starts clamping the drive shaft 41. The CPU 91 sets the clamp confirmation time in the clamp confirmation time counter (S22). The CPU 91 stores the clamp confirmation time counter in the RAM 93. The clamp confirmation time is the time from when the clamp device 68 starts clamping the drive shaft 41 to when it is completed.

The CPU 91 determines whether the clamp confirmation time has elapsed (S23). The CPU 91 determines S23 based on the value of the clamp confirmation time counter set in S22. When the CPU 91 determines that the value of the clamp confirmation time counter is not 0 and the clamp confirmation time has not elapsed (S23: NO), the process is returned to S23 and the process is repeated. When the value of the clamp confirmation time counter is 0 and the CPU 91 determines that the clamp confirmation time has elapsed (S23: YES), the CPU 91 stops the C-axis motor 66 (S24). When the clamping device 68 completes the clamping, the CPU 91 detects the rotational position of the drive shaft 41 from the detection result of the encoder 76.

As shown in FIG. 5, the CPU 91 determines whether the displacement amount, which is the displacement amount between the predetermined rotation position set by the user on the drive shaft 41 and the rotation position of the clamp device 68 after the completion of clamping, is equal to or less than the error threshold value ( S31). For example, when the torque for clamping the drive shaft 41 by the clamping device 68 is large, the amount of misalignment may not be zero. The error threshold is a threshold for the CPU 91 to determine whether the machining accuracy of the machine tool 100 may be affected by the misalignment of the drive shaft 41. When the CPU 91 determines that the amount of misalignment is equal to or less than the error threshold value (S31: YES), the CPU 91 ends the C-axis alignment process. At this time, assuming that the clamping device 68 has normally completed the clamping, the machine tool 100 starts machining the work.

When the CPU 91 determines that the misalignment amount is larger than the error threshold value (S31: NO), the CPU 91 determines whether the misalignment amount is equal to or less than the permissible deviation value (S32). The deviation allowable value is a threshold value for the CPU 91 to determine whether the clamp device 68 executes the retry process described later. The deviation tolerance is a threshold value for the amount of displacement. The deviation tolerance value is larger than the error threshold value, for example, 5 to 10 times the error threshold value.

When the CPU 91 determines that the displacement amount is equal to or less than the deviation allowable value (S32: YES), the CPU 91 determines whether the variable N is equal to or less than the maximum number of retries (S33). The maximum number of retries is a threshold value for the CPU 91 to determine whether the clamp device 68 executes the retry process described later. The maximum number of retries is a threshold for the variable N. When the CPU 91 determines that the variable N is less than the maximum number of retries (S33: YES), the processing shifts to S51 (see FIG. 6).

As shown in FIG. 6, the CPU 91 adds 1 to the variable N (S51). The CPU 91 sets the motor waiting time in the motor waiting time counter (S52). The CPU 91 stores the motor waiting time counter in the RAM 93. The motor waiting time is the waiting time until the stopped C-axis motor 66 is driven again.

The CPU 91 determines whether the motor waiting time has elapsed (S53). The CPU 91 determines S53 based on the value of the motor waiting time counter set in S52. When the CPU 91 determines that the value of the motor waiting time counter is not 0 and the motor waiting time has not elapsed (S53: NO), the process is returned to S53 and the process is repeated. When the value of the motor waiting time counter is 0 and the CPU 91 determines that the motor waiting time has elapsed (S53: YES), the processing shifts to S61.

The CPU 91 turns on the unclamp output signal (S61). At this time, the clamping device 68 starts unclamping the drive shaft 41. The CPU 91 sets the unclamp confirmation time in the unclamp confirmation time counter (S62). The CPU 91 stores the unclamp confirmation time counter in the RAM 93. The unclamp confirmation time is the time from when the clamping device 68 starts unclamping the drive shaft 41 to when it is completed. The CPU 91 drives the C-axis motor 66 (S63). The CPU 91 controls the C-axis motor 66 based on the detection result of the encoder 76 to move the drive shaft 41 to a predetermined rotation position.

The CPU 91 determines whether the unclamp confirmation time has elapsed (S71). The CPU 91 determines S71 based on the value of the unclamp confirmation time counter set in S62. When the CPU 91 determines that the value of the unclamp confirmation time counter is not 0 and the unclamp confirmation time has not elapsed (S71: NO), the process is returned to S71 and the process is repeated. When the value of the unclamp confirmation time counter is 0 and the CPU 91 determines that the unclamp confirmation time has elapsed (S71: YES), the processing shifts to S72.

The CPU 91 sets the clamp waiting time in the clamp waiting time counter (S72). The CPU 91 stores the clamp waiting time counter in the RAM 93. The clamp waiting time is the waiting time from when the clamping device 68 completes the unclamping of the drive shaft 41 to when the clamping device 68 clamps again.

The CPU 91 determines whether the clamp waiting time has elapsed (S73). The CPU 91 determines S73 based on the value of the clamp waiting time counter set in S72. When the CPU 91 determines that the value of the clamp waiting time counter is not 0 and the clamp waiting time has not elapsed (S73: NO), the process is returned to S73 and the process is repeated. When the value of the clamp waiting time counter is 0 and the CPU 91 determines that the clamp waiting time has elapsed (S73: YES), the processing shifts to S81.

The CPU 91 turns off the unclamp output signal (S81). At this time, the clamping device 68 starts clamping the drive shaft 41. The CPU 91 sets the clamp confirmation time in the clamp confirmation time counter (S82). The processing of S81 and S82 is the same as that of S21 and S22 (see FIG. 4).

The CPU 91 determines whether the clamp confirmation time has elapsed (S83). The processing of S83 is the same as that of S23 (see FIG. 4). When the CPU 91 determines that the clamp confirmation time has not elapsed (S83: NO), the process is returned to S83 and the process is repeated. When the CPU 91 determines that the clamp confirmation time has elapsed (S83: YES), the CPU 91 stops the C-axis motor 66 (S84). The processing of S84 is the same as that of S24 (see FIG. 4).

As described above, when the CPU 91 determines that the amount of misalignment of the drive shaft 41 is larger than the error threshold value (S31: YES, see FIG. 5), the CPU 91 executes the processes S51 to S84. In the processes of S51 to S84, the clamping device 68 unclamps the drive shaft 41 once and then clamps it again. The processes of S51 to S84 are collectively referred to as "retry process". After executing the retry process, the CPU 91 returns the process to S31 (see FIG. 5).

As shown in FIG. 5, after executing the retry process (see FIG. 6), the CPU 91 determines whether the amount of misalignment is equal to or less than the error threshold value (S31). When the CPU 91 determines that the amount of misalignment is equal to or less than the error threshold value after the retry process (S31: YES), the CPU 91 ends the C-axis alignment process. At that time, the machine tool 100 starts machining the work.

When the CPU 91 determines that the amount of misalignment is larger than the error threshold value even after the retry process (S31: NO), the CPU 91 repeatedly executes the retry process (see FIG. 6) after determining S32 and S33. The CPU 91 adds 1 to the variable N each time the retry process is repeated.

When the CPU 91 determines that the amount of misalignment is larger than the error threshold value (S31: NO) and further larger than the permissible deviation value (S32: NO), the processing shifts to S41. Further, when the variable N reaches the maximum number of retries as a result of repeatedly executing the retry process (S33: NO), the CPU 91 shifts the process to S41. The CPU 91 displays on the display unit 84 that the drive shaft 41 may be displaced from the predetermined rotation position set by the user, which may affect the machining accuracy of the machine tool 100 (S41). The CPU 91 does not perform the retry process because the clamping device 68 cannot normally complete the clamping (S42). At that time, the machine tool 100 stops processing the work. The CPU 91 ends the C-axis alignment process.

In the above description, the C-axis motor 66 corresponds to the servo motor of the present invention, the clamp device 68 corresponds to the clamp portion of the present invention, the predetermined rotation position corresponds to the first rotation position of the present invention, and S11 and S12. The CPU 91 that executes the above corresponds to the first control unit of the present invention, the CPU 91 that executes S21 corresponds to the second control unit of the present invention, the amount of misalignment corresponds to the amount of deviation of the present invention, and the error threshold and the deviation. The permissible value corresponds to the threshold of the present invention, the CPU 91 that executes S31 and S32 corresponds to the determination unit of the present invention, the error threshold corresponds to the first threshold of the present invention, and the CPU 91 that executes S61 and S81 is the present invention. It corresponds to the third control unit of the present invention, the clamp waiting time corresponds to the first time of the present invention, the variable N corresponds to the first number of times of the present invention, and the maximum number of retries corresponds to the second threshold value of the present invention. , The CPU 91 that executes S42 corresponds to the first stop unit of the present invention, the deviation allowable value corresponds to the third threshold value of the present invention, the display unit 84 corresponds to the notification unit of the present invention, and the deviation allowable value is the present invention. The CPU 91 that corresponds to the fourth threshold of the present invention and executes S41 and S42 corresponds to the second stop portion of the present invention, the motor waiting time corresponds to the second time of the present invention, and the CPU 91 that executes S24 and S84 corresponds to the second stop portion of the present invention. Corresponds to the third stop of the present invention.

As described above, the numerical control device 1 includes a CPU 91. The CPU 91 controls the C-axis motor 66 to move the drive shaft 41 to a predetermined rotation position set by the user (S11). When the drive shaft 41 moves to a predetermined rotation position (S12: YES), the CPU 91 turns off the unclamp output signal (S21) and causes the clamping device 68 to start clamping the drive shaft 41. When the clamping device 68 completes the clamping of the drive shaft 41 (S23: YES), the CPU 91 determines whether the misalignment amount is equal to or less than the error threshold value (S31). When the CPU 91 determines that the amount of misalignment is larger than the error threshold value (S31: NO), the CPU 91 executes retry processing (S51 to S84). Therefore, the numerical control device 1 can accurately stop the drive shaft 41 at a designated rotation position.

In the retry processing (S51 to S84), the CPU 91 sets the clamp waiting time set by the user in the clamp waiting time counter when the clamping device 68 completes the unclamping of the drive shaft 41 (S71: YES) (S72). .. When the clamp waiting time has elapsed (S73: YES), the CPU 91 turns off the unclamp output signal (S81) and clamps the drive shaft 41. Therefore, the CPU 91 can control the C-axis motor 66 so that the drive shaft 41 moves to a designated rotation position during the clamp waiting time. Therefore, the numerical control device 1 can accurately stop the drive shaft 41 at a designated rotation position.

When the misalignment amount is larger than the error threshold value (S31: NO), the CPU 91 repeatedly executes retry processes (S51 to S84) until the misalignment amount becomes equal to or less than the error threshold value. The CPU 91 adds 1 to the variable N each time the retry processing (S51 to S84) is executed (S51). When the value of the variable N reaches the maximum number of retries set by the user (S33: NO), the CPU 91 cancels the retry process (S42). Therefore, the user can easily determine the malfunction of the control of the numerical control device 1 based on the value of the variable N.

When the clamping device 68 completes the clamping of the drive shaft 41 (S23: YES), the CPU 91 determines whether the displacement amount is equal to or less than the deviation allowable value (S32). When the CPU 91 determines that the amount of misalignment is larger than the permissible deviation value (S32: NO), the drive shaft 41 may be misaligned from the predetermined rotation position, which may affect the machining accuracy of the machine tool 100. It is displayed on the display unit 84 (S41). Therefore, the user can easily grasp the malfunction of the control of the numerical control device 1 from the display of the display unit 84.

In the retry processing (S51 to S84), when the clamping device 68 completes the clamping of the drive shaft 41 (S83: YES), the CPU 91 determines whether the displacement amount is equal to or less than the deviation allowable value (S32). When the CPU 91 determines that the amount of misalignment is larger than the permissible deviation value (S32: NO), the drive shaft 41 may be misaligned from the predetermined rotation position, which may affect the machining accuracy of the machine tool 100. It is displayed on the display unit 84 (S41). At that time, the CPU 91 cancels the retry process (S42). Therefore, the user can easily grasp the malfunction of the control of the numerical control device 1 from the display of the display unit 84.

When the clamping of the drive shaft 41 by the clamping device 68 is completed (S23: YES, S83: YES), the CPU 91 stops the C-axis motor 66 (S24, S84). When the misalignment amount is larger than the error threshold value (S31: NO), the CPU 91 sets the motor waiting time in the motor waiting time counter in the retry processing (S51 to S84) (S53). When the motor waiting time elapses (S53: YES), the CPU 91 unclamps the drive shaft 41 by the clamping device 68 (S61) to drive the C-axis motor 66 (S63). The CPU 91 clamps the drive shaft 41 by the clamping device 68 (S81). When the clamping device 68 is clamping the drive shaft 41, the CPU 91 stops the C-axis motor 66 during the motor waiting time, so that the torque generated by the C-axis motor 66 on the drive shaft 41 is reduced. Therefore, the numerical control device 1 can suppress an increase in the amount of misalignment of the drive shaft 41.

The encoder 76 detects the absolute position of the rotation position of the drive shaft 41. The CPU 91 determines the relationship between the position deviation amount, which is the difference between the detected rotation position of the drive shaft 41 and the predetermined rotation position, and the error threshold value (S31) or the deviation tolerance value (S32). Since the numerical control device 1 can detect the rotation position of the drive shaft 41, the drive shaft 41 can be accurately stopped at the designated rotation position.

The present invention is not limited to the above examples. In the above embodiment, the CPU 91 executes the retry process on the drive shaft 41 connected to the C-axis table 40, but the present invention is not limited to this. The right side drive mechanism unit 28 may include a clamp device, and the CPU 91 may execute a retry process on the support shaft of the right side drive mechanism unit 28 connected to the A-axis table 20. The machine tool 100 may have a B-axis which is a rotation axis parallel to the Y-axis and drive axes of other rotation axes, and a retry process may be executed on these drive axes.

In the above embodiment, the clamp device includes a disc brake, but other braking devices such as a drum brake may be used. The drive system of the clamp device may be pneumatic or hydraulic, and is not limited.

In the above embodiment, the CPU 91 specifies the rotation position of the drive shaft 41 by the encoder 76, but the one that detects the rotation position is not limited to the encoder 76, for example, from the detection results of a plurality of position sensors. The rotation position of the drive shaft 41 may be detected.

The maximum number of retries, the allowable deviation value, and the clamp waiting time are set by the user, but may be predetermined values set in advance. The deviation allowable value may differ between when the drive shaft 41 is clamped (S21) for the first time and when the drive shaft 41 is clamped (S81) in the retry process.

In the above embodiment, when the CPU 91 inputs the unclamp output signal to the drive circuit 58, the clamp device 68 unclamps the drive shaft 41, and when the CPU 91 does not input the unclamp output signal to the drive circuit 58, the clamp device 68. Clamped the drive shaft 41, but is not limited to this. When the CPU 91 inputs a clamp output signal to the drive circuit 58, the clamp device 68 may clamp the drive shaft 41. At that time, when the CPU 91 does not input the clamp output signal to the drive circuit 58, the clamp device 68 may unclamp the drive shaft 41.

The mode of notification of S41 may differ between when the drive shaft 41 is clamped (S21) for the first time and when the drive shaft 41 is clamped (S81) in the retry process.

1 Numerical control device 40 C-axis table 41 Drive shaft 50 C-axis drive unit 66 C-axis motor 68 Clamp device 76 Encoder 100 Machine tool

Claims (8)

In a numerical control device capable of controlling a machine tool having a servomotor, a drive shaft that is rotationally driven by the servomotor, and a clamp portion that clamps the drive shaft.
A first control unit that controls the servomotor and rotates the drive shaft to the first rotation position, which is a designated rotation position.
When the drive shaft is rotated to the first rotation position by the first control unit, a second control unit that controls the clamp unit to clamp the drive shaft and
A determination unit that determines the relationship between the deviation amount, which is the difference between the rotation position of the drive shaft and the first rotation position, and the threshold value.
When the determination unit determines that the amount of deviation after the clamp of the drive shaft by the second control unit is completed is equal to or greater than a predetermined first threshold value, the clamp unit is controlled to release the drive shaft. A numerical control device including a third control unit that clamps and then controls the clamp unit to clamp the drive shaft. The third control unit
The numerical control device according to claim 1, wherein when the first time elapses after the unclamping of the drive shaft is completed, the clamp portion is controlled to clamp the drive shaft. The third control unit further
Repeated control of repeating unclamping and clamping of the drive shaft is executed until the amount of deviation after controlling the clamp portion and clamping the drive shaft becomes less than the first threshold value.
When the first number of times of the repetitive control by the third control unit is equal to or more than a predetermined second threshold value, the first stop unit for stopping the repetitive control by the third control unit is provided. The numerical control device according to claim 1 or 2. When the determination unit determines that the deviation amount after the clamp of the drive shaft by the second control unit is completed is equal to or greater than the third threshold value having a value larger than the first threshold value, the notification unit is notified. The numerical control device according to any one of claims 1 to 3. When the determination unit determines that the deviation amount after the clamp of the drive shaft by the third control unit is completed is equal to or greater than the fourth threshold value having a value larger than the first threshold value, the third control unit determines. The numerical control device according to claim 3, further comprising a second stop unit that stops the repetitive control and notifies the notification unit. When the determination unit determines that the deviation amount is equal to or greater than the first threshold value, the third control unit further includes a third stop unit that stops the driving of the servomotor until the second time elapses. ,
The numerical control device according to any one of claims 1 to 5, wherein when the second time elapses, the clamp portion is controlled to clamp the drive shaft. A detector capable of detecting the rotation position is provided.
Any of claims 1 to 6, wherein the determination unit determines the relationship between the deviation amount, which is the difference between the rotation position and the first rotation position detected by the detection unit, and the threshold value. Numerical control device described in. A machine tool provided with the numerical control device according to any one of claims 1 to 7.

Images