JPH10201279A - Motor synchronous rotation control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synchronous rotation control method which makes it possible to eliminate rapid speed change at starting or releasing of synchronous control. SOLUTION: A feedback pulse P1 from a position coder 7 attached to a main main-axis 3 is multiplied by a magnification R, to obtain a movement command value wherein a sub main-axis 4 is the same rotation speed as the main main-axis 3. With a synchronization command inputted, a movement command value is increased or decreased by an acceleration/deceleration means 12 until a target movement command value is reached where both main axes 3 and 4 are at the same rotation speed, and then the movement command is outputted to a servo motor 2 which drives the sub main axis through a contact point (a) of a switch SW1. When reaching the target movement command value, the switch SW1 is changed over to p-side, and a value obtained by multiplying the feedback pulse P1 with the magnification R is outputted as a movement command value. Thus, both main axes 3 and 4 rotate at the same speed. Further, with differential speed command inputted, a switch SW2 is turned on, and duplexed with such a movement command value as corresponding to differential speed, for outputting to the servo motor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control method for synchronously rotating a shaft driven by a motor in a machine tool or the like.

[0002]

2. Description of the Related Art A control method for synchronizing and rotating two axes such as a compound lathe (turning center) having a main spindle for rotating a workpiece and a sub spindle for rotating a tool is disclosed in Japanese Patent Laid-Open Publication No. Hei.
It is publicly known, for example, in Japanese Patent Publication No. 31518. The invention described in this known Japanese Patent Application Laid-Open No. 2-311518 inputs a feedback pulse from a position coder attached to a main spindle as a position command of a servo motor for driving the sub-main spindle, and further inputs a feedback pulse to the rotation speed of the sub-main spindle. A position command corresponding to the rotational speed difference is added and input, and the position feedback control and the speed feedback control are performed to drive the servo motor of the sub-spindle. Thus, the sub-spindle is driven to rotate at a differential speed inputted with respect to the rotation speed of the spindle, and tapping is performed.

[0003]

In the above-described synchronous rotation control method for the main spindle and the sub spindle, the feedback pulse from the position coder of the main spindle is input as a position command for the sub spindle at the start of synchronization. There is a drawback that a large speed change occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a synchronous rotation control method which eliminates a sudden change in speed when starting and canceling synchronous control.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a movement command for a position loop control of a servo motor for driving a sub-spindle, which is obtained by multiplying the number of feedback pulses from a position detector attached to the main spindle by a set magnification. In the synchronous rotation control method in which the sub spindle is driven at the same rotational speed as the main spindle, when the synchronous rotation command is input, the sub spindle is multiplied by a set magnification to the amount of the feedback pulse from the position detector to set the sub spindle to the main spindle. And a movement command value for rotating at the same rotation speed. The obtained movement command value is set as a target movement command value, and the movement command value instructed to the servo motor is sequentially increased or decreased until reaching the target movement command value. When the movement command value reaches the target movement command value, the value obtained by multiplying the number of feedback pulses from the position detector by the set magnification is output as the movement command value of the servo motor, so that the sub spindle is the same as the main spindle. Control is performed to achieve the rotation speed.

When a differential speed rotation command is input,
A movement command value for rotating the sub-spindle at the same rotational speed as the main spindle is obtained by multiplying the feedback pulse amount from the position detector by the set magnification, and a movement command corresponding to the differential speed commanded by the movement command value. The values are added to obtain a target movement command value. Then, the movement command value instructed to the servo motor is sequentially increased or decreased until the target movement command value is reached. When the movement command value reaches the target movement command value, a value obtained by adding a movement command value corresponding to the differential speed to a value obtained by multiplying the number of feedback pulses from the position detector by a set magnification is used as the movement command of the servo motor. By outputting the value as a value, control is performed so that the rotational speeds of the sub-main shaft and the main main shaft rotate at the command differential speed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram for explaining an operation principle according to an embodiment of the present invention. The main spindle 3 is driven by the spindle motor 1 via transmission means 5 such as a gear and a timing belt. A position coder 7 as a position detector is connected to the main spindle 3 via a similar transmission means 6 so as to detect the rotational position of the main spindle 3. The sub spindle 4 is a servo motor 2
Driven through the transmission means 8. The servo motor 2 has a rotational position and a position for detecting the speed of the servo motor.
A speed detector 9 is mounted. Reference numeral 10 denotes a conversion unit that multiplies the feedback pulse output from the position coder 7 by a magnification R to generate a movement command to the servomotor 2 necessary for rotating the sub spindle at the same speed as the main spindle. The magnification R is determined by the reduction ratio of the transmission means between the main spindle 3 and the position coder 7 and the reduction ratio of the transmission means 8 between the servo motor 2 and the sub spindle in order to rotate the main spindle 3 and the sub spindle 4 at the same speed. Determined by

In a normal operation in which the sub-spindle 4 is independently driven and controlled without performing the synchronous rotation control of the main main shaft 3, the switch SW 1 is connected to the contact a and the sub-spindle 4 is connected. The movement command 11 is subjected to acceleration / deceleration control via acceleration / deceleration means 12 to output a movement command to the servomotor 2, and the position feedback signal Pf fed back from the position / speed detector 9 is subtracted from the movement command. In the same manner as described above, the position feedback control and the speed feedback control are performed, and the servo motor 2 is driven to control the position and speed of the sub spindle.

When a synchronous rotation command of the sub spindle 4 is output to the main spindle 3, a movement command value is multiplied by a value obtained by multiplying the number of feedback pulses output from the position coder 7 in the predetermined cycle by the above-mentioned magnification. Till the acceleration / deceleration means 1
At 2, acceleration and deceleration are performed and a movement command is output. When acceleration / deceleration is completed and the rotation speed of the sub spindle 4 becomes the same as the rotation speed of the main spindle 3, the switch SW1 is switched to connect to the contact b, and the movement command to the servo motor 2 is fed back from the position coder 7. A value obtained by multiplying the number of pulses by the magnification R is instructed to the servo motor 2 as a movement instruction.
As a result, the sub spindle 4 rotates synchronously with the main spindle 3 at the same speed.

Further, when the speed difference command 13 is output for tapping or the like, the switch SW2 is closed, and the means 14 for converting the speed difference into a movement command converts the speed difference into a movement command for a predetermined period from the input difference speed. After the conversion, the acceleration / deceleration control is performed and output to the servo motor 2. A movement command based on a differential speed is added to a movement command obtained by multiplying the number of feedback pulses from the position coder 7 in which the sub-spindle 4 is the same as the main spindle 3 by a magnification R, and the movement command to the servo motor 2 is obtained. Therefore, the sub spindle 4 rotates with the speed difference of the speed difference inputted to the main spindle 3.

When the synchronous control is released, the switch SW1 is switched to the contact a, and the switch SW2 is turned off. Then, as in the conventional case, the movement command is accelerated / decelerated by the acceleration / deceleration means 12 from the current movement command to the movement command instructed at the time of synchronization release, and the movement command is output, so that the ordinary servo motor 2 is controlled. The above is the operation principle of the embodiment of the present invention. FIG. 2 is a functional block diagram illustrating a main part of a control device 100 of the machine tool that executes the synchronous rotation control method according to the embodiment.

The processor 20 of the control device 100 is a processor that controls the control device 100 as a whole. The processor 20 reads a system program stored in the ROM 21 via the bus 29, and controls the control device 100 as a whole according to the system program.
The RAM 22 stores temporary calculation data and display data, various data input by the operator via the CRT / MDI unit 70, and the like. The CMOS memory 23 is backed up by a battery (not shown),
0 is configured as a non-volatile memory that retains its storage state even when the power supply is turned off, and stores a machining program read via the interface 24, a machining program input via the CRT / MDI unit 70, and the like. It has become so. Further, in the ROM 21, various system programs for executing processing in an edit mode and processing for automatic operation required for creating and editing a machining program are written in advance.

The interface 24 is connected to the control device 100
This is an interface for an external device connectable to an external device, and an external device 72 such as a floppy cassette adapter is connected to the interface.

A PMC (programmable machine controller) 25 controls an actuator of an auxiliary device of the machine tool by a sequence program stored in the control device 100. That is, the M function commanded by the machining program,
In accordance with the S function and the T function, these sequence programs convert the necessary signals on the auxiliary device side and output the signals from the I / O unit 26 to the auxiliary device side. Auxiliary devices such as various actuators are operated by this output signal. Further, it receives signals from various switches and the like of an operation panel provided in the main body of the machine tool, performs necessary processing, and passes the signals to the processor 20.

The interface 28 is connected to a manual pulse generator 71 and receives a pulse from the manual pulse generator 71. The manual pulse generator 71 is mounted on the operation panel of the machine tool, and is used for precisely positioning the tool rest of the machine tool by controlling each axis by the distribution pulse based on the manual operation.

The axis control circuit for each of the X, Y, and Z axes for moving the tool and the axis control circuits 30 to 33 for the sub-spindle receive a movement command for each axis from the processor 20 and servo commands for each axis. Output to amplifiers 40-43. In response to this command, the servo amplifiers 40 to 43
0 to 52 and 2 are driven. Servo motor of each axis 50 ~
A position / speed detector is built in each of 52 and 2, and a position / speed feedback signal is fed back from the position / speed detector. Although the description of the position signal feedback and the speed feedback is omitted in FIG. 2, the position and speed feedback control is performed by the axis control circuits 30 to 33.

The spindle control circuit 60 receives a main spindle rotation command and outputs a spindle speed signal to a spindle amplifier 61. Upon receiving the spindle speed signal, the spindle amplifier 61 rotates the spindle motor 1 at the commanded rotation speed and drives the main shaft 3 to rotate. The position coder 7 coupled to the main shaft outputs a feedback pulse in synchronization with the rotation of the main shaft 3, and the feedback pulse is output to the interface 6.
The data is read by the processor 20 at predetermined intervals via the processor 2.

FIG. 3 is a flowchart of a process centering on the synchronous rotation control process of the servo motor 2 for driving the sub spindle 4 which is executed by the processor 20 of the machine tool control device at predetermined intervals. The control of the other servo motors and the spindle motor 1 is omitted because it is the same as the conventional one.

The processor 20 determines whether or not a synchronization release command has been input from the machining program or the CRT / MDI unit 70 (step S1), and if not, determines whether or not the flags F3 and F1 are "1". (Steps S2 and S3) If it is not "1", it is determined whether or not a synchronization command has been input (Step S4). A movement command is output to the user (step S2
8). The flags F1 and F3 and the flag F
2 and F4 are set to "0" by default.

Then, when a synchronization command is input from the machining program or the CRT / MDI unit 70 (a synchronization command is input from the machining program during automatic operation or from the CRT / MDI unit 70 during manual operation). Proceeding from step S4 to step S5, the flag F1 is set to "1" to store that synchronization control is being performed. Then, the movement command value Pc2 in the current predetermined cycle within the cycle
Is stored in a register (step S6), the feedback pulse amount P1 in the preprocessing cycle is read from the position coder 7 (step S7), and the magnification R set to the feedback pulse amount P1 (this magnification R is as described above) Is multiplied by a value obtained from the reduction ratio of the transmission means 6 and 8 so that the rotation speed of the main spindle 3 and the rotation speed of the sub spindle 4 are the same. A target movement command value Pb that becomes the same rotational speed as that of No. 3 is obtained and stored (step S8).

Next, the set amount ΔP is added to the current movement command value Pc2 stored in step S6, and the movement command value P
Rewrite and store the register as c2 (Step S
9). Although the set amount ΔP has a sign and is omitted in FIG. 3, the current movement command value Pc2 obtained in step S6 is compared with the target movement command value Pb obtained in step S8, and the target movement command value Pb is calculated. If it is larger, a plus set amount Δ
It becomes P and becomes the moving command value Pc2 accelerated. On the other hand, if the movement command value Pb is smaller, a negative set amount ΔP is obtained.
It becomes the decelerated movement command value Pc2.

Next, the movement command value Pc2 is used in step S8.
It is determined whether or not the target movement command value Pb obtained in step S1 is exceeded (step S10). If not, the movement command value Pc2 is output to the axis control circuit 33 of the servo motor 2 (step S1).
1) The process of the cycle ends. The axis control circuit 33 receives this movement command and performs position and speed feedback control.

When a synchronization command is input in a state where the rotation speed of the sub-main shaft 4 is lower than the rotation speed of the main main shaft 3, a plus set amount ΔP is added in step S9 and increased by ΔP from the current movement instruction. The movement command is output, and the sub spindle 4 is accelerated. Conversely, when a synchronization command is input in a state where the rotation speed of the sub-main shaft 4 is higher than the rotation speed of the main main shaft 3, in step S9, a minus set amount ΔP is added and the movement is reduced by ΔP from the current movement command. The command is output, and the sub spindle 4 is decelerated.

In the next cycle, since the flag F1 is set to "1", the process proceeds from step S3 to step S14, where the flag F1 to which "1" is set at the end of acceleration / deceleration is set.
2 is “1”, and is “0” at first. Therefore, the process proceeds to step S7 to execute steps S7 to S10 of the above-described processing.
Is performed. If the updated movement command value Pc2 does not exceed the target movement command value Pb, the process proceeds to step S11, where the updated movement command value Pc2 is output, and the servomotor 2 is accelerated / decelerated. Hereinafter, as long as the movement command value does not exceed the target movement command value Pb in step S10, steps S1 to S3, S14, S7 to S10, S1 are performed in each cycle.
1 is repeatedly executed to perform acceleration / deceleration processing with constant acceleration.

If the movement command value P2c increases or decreases and exceeds the target movement command value Pb, it is determined in step S10.
When the determination is made in step S10, the process proceeds from step S10 to step S12, in which the flag F2 indicating the completion of acceleration / deceleration is set to "1", and the step S7 is set in the register storing the movement command value P2c.
Feedback pulse amount P from position coder 7 read in
A value obtained by multiplying 1 by the magnification R is stored, and this value is output as the movement command value P2c (step S13), and the processing of the processing cycle ends. As a result, the sub spindle 4 rotates at the same speed as the rotation speed of the main spindle 3.

In the next cycle, the flags F1 and F2 are set to "1".
Since the flag F2 is "1" since the flag F2 is "1", the flow goes to step S15 to read the feedback pulse amount P1 from the position coder 7, and the difference speed command is set to the machining program. Or CR
It is determined whether or not it has been input from the T / MDI unit 70 (step S16). If not, the flow proceeds to step S13, and the value obtained by multiplying the feedback pulse amount P1 read in step S15 by the magnification R is the movement command value P2c. And output. As long as the speed difference command is not input, from the subsequent processing cycle, steps SS1 to S3, S14,
The processes of S15, S16, and S13 are repeatedly executed. Thus, the sub-main shaft 4 rotates at the same speed as the rotation speed of the main main shaft 3.

While the sub-main shaft 4 and the main main shaft 3 are rotating at the same speed, for example, from the main main shaft 3 to the sub-main shaft 4
When a work such as re-gripping of a workpiece or reversing of a workpiece is performed and a synchronization release command is input, the process proceeds from step S1 to step S27, and the flags F1 to F27 are set.
4 is set to "0", and normal processing is executed (step S28). In the normal processing, a speed command is obtained from the value of the movement command value P2c stored in the register, and acceleration / deceleration processing is performed in the same manner as in the past based on the speed command at the time of transition from the speed command to the normal processing. A movement command will be output. This point is omitted in FIG.

On the other hand, when the sub-spindle 4 is rotating at the same speed as the rotation speed of the main spindle 3, that is, while the processes of steps S1 to S3, S14, S15, S16 and S13 are being executed, tapping is performed. When a differential speed command is input for processing or the like, the process proceeds from step S16 to step S17, and a flag F3 for storing that the differential speed control is being performed is set to "1". (Step S1)
8). The differential speed Vx also has a sign, and the corresponding movement command value Px has the same sign as the differential speed. Next, step S
The target movement command value Pd is obtained by adding the movement command value Px corresponding to the differential speed to the value obtained by multiplying the feedback pulse P1 read at 15 by the magnification R (step S19). Further, the set amount ΔP is added to the movement command value P2c stored in the register, and a new movement command value Pc2 is obtained (step S20). The set amount ΔP also has a sign, which is the same as the sign of the differential speed command Vx. That is, when the differential speed command Vx is negative, the set amount ΔP is also negative, and the updated movement command value P2c decreases. Conversely, when the differential speed command Vx is positive, the set amount Δ
P also becomes positive, and the updated movement command value P2c increases.

Next, it is determined whether or not the updated movement command value P2c has exceeded the target movement command value Pd obtained in step S19 (step S21). If not, an updated movement command value P2c is output (step S21). S22), the processing of the processing cycle ends. From the next cycle, since the flag F3 is set to "1", the process proceeds from step S2 to step S24, and since the flag F4 is "0", the process proceeds to step S25 to read the feedback pulse amount P1 and read step S25. The process shifts to S19, performs the above-described process, and proceeds to step S19.
If the update movement command value P2c does not exceed the target movement command value Pd at 21, an update movement command value P2c is output. Hereinafter, this processing is repeatedly executed for each processing cycle.

If it is determined in step S21 that the updated movement command value P2c has exceeded the target movement command value Pd, step S21 is executed.
21 to step S23, the flag F4 is set to "1", and the feedback pulse amount P read in step S15 is set.
The value obtained by multiplying 1 by the magnification R is the differential speed V obtained in step S18.
The movement command value Px corresponding to x is added and output as the movement command value P2c of the cycle (step S27). As a result, the sub-spindle 4 rotates at a rotation speed having a difference of the difference speed Vx commanded to the main spindle 3. From the subsequent processing cycle, the process proceeds to steps S1, S2, and S24,
Since the flag F4 is set to "1", the process proceeds from step S24 to step S26 to read the feedback pulse amount P1 and move the value obtained by multiplying the read feedback pulse amount P1 by the magnification R and corresponding to the differential speed Vx. The command value Px is added and output as the movement command value P2c in the cycle, and the servo motor 2 is driven. As a result, the sub spindle 4 becomes the main spindle 3
Is rotated with a speed difference of the command differential speed Vx.

If a synchronization release command is input to end the differential speed control, the process proceeds from step S1 to step S1.
27, the above-described processing is performed, and the control returns to the normal control of the sub spindle.

If the rotational speed of the main spindle 3 does not change greatly when the synchronous control and the differential speed control are shifted, the process may shift to step S9 instead of shifting from step S14 to step S7. Good. Further, instead of shifting from step S25 to step S19, the process may shift to step S20.

In the above description of the embodiment, an example has been described in which the synchronous control is performed by the synchronous command, and after the synchronous speed is reached, the differential speed command is input to perform the differential speed control. When an input is made, first, synchronous control is performed, and after reaching the synchronous speed, differential speed control is performed. Therefore, a second embodiment of a control method in which when the differential speed command is input, the control is not performed once to the synchronous speed but directly reaches the command differential speed will be described.

FIG. 4 is a flowchart executed by the processor 20 at predetermined intervals in the second embodiment. It is determined in steps T1 to T5 whether a synchronization command, a differential speed command, or a synchronization (differential speed) release command has been input. When a synchronization command is input, the same processing as in the first embodiment shown in FIG. 3 is executed. That is, steps S4, S5 to S13, S14, and S15 in the first embodiment correspond to steps T4, T6 to T14, T15, and T16 in the second embodiment.

When a differential speed command is input, the flag F
3 is set to "1", the movement command value P2c in the current processing cycle is stored in a register, and the input differential speed Vx is converted into the movement command value Px in the processing cycle corresponding to the differential speed Vx. 7 is read, and a value obtained by multiplying the feedback pulse amount P1 by a magnification R is used as the movement command value P1.
The target movement command value Pd is obtained by adding x. Further, the set amount ΔP is added (subtracted) to the movement command value P2c stored in the register, and it is determined whether the updated movement command value P2c exceeds the target movement command value Pd (steps T17 to T17).
23). If not, an updated movement command value P2c is output (Step T24), and from the next cycle, Step T2
Then, the process shifts to step T27. Since the flag F4 is "0", the process shifts to step T20 to perform the above-described processing.

If it is determined in step T23 that the updated movement command value P2c has exceeded the target command value Pd, the flag F4
Is set to "1" (step T25), and the feedback pulse P
Movement command value Px corresponding to the differential speed multiplied by 1 multiplied by magnification R
Is output as the movement command value P2c (step T26). From the next cycle, steps T2, T27,
The process proceeds to T28, where the feedback pulse P1 is read, and a value obtained by adding the movement command value Px corresponding to the differential speed to the value obtained by multiplying the feedback pulse P1 by the magnification R is output as the movement command value P2c (step T26). As a result, the sub spindle 4 is driven with a speed difference of the input differential speed with respect to the main spindle 3.

[0037]

According to the present invention, acceleration / deceleration processing of the rotational speed of the sub spindle is performed at the start and release of synchronous rotation control of the main spindle and the sub spindle, and at the start and release of differential speed control. Synchronization and differential speed control can be smoothly started and released without causing a shock or the like due to a large change in the rotation speed of the main shaft.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an operation principle of an embodiment of the present invention.

FIG. 2 is a block diagram of a control device of the machine tool for implementing the embodiment.

FIG. 3 is a flowchart mainly showing a synchronous and differential speed control process in the embodiment.

FIG. 4 is a flowchart mainly showing a synchronization and differential speed control process in the second embodiment.

[Explanation of symbols]

 Reference Signs List 1 spindle motor 2 servo motor 3 main spindle 5, 6, 8 transmission means 7 position coder 9 position / speed detector 10 means for multiplying feedback pulse amount by magnification R

Claims (2)

[Claims] A value obtained by multiplying the number of feedback pulses from a position detector attached to a main spindle by a set magnification is output as a movement command for position loop control of a servo motor for driving a sub spindle, and the sub spindle is driven by the main spindle. In the synchronous rotation control method of driving at the same rotational speed as above, when a synchronous rotational command is input, the sub spindle is rotated at the same rotational speed as the main spindle by multiplying the amount of feedback pulse from the position detector by a set magnification. The movement command value is obtained as a target movement command value, and the movement command value commanded to the servo motor is sequentially increased or decreased until the movement command value reaches the target movement command value. For example, a value obtained by multiplying the number of feedback pulses from the position detector by the set magnification is output as the movement command value of the servo motor, and the sub spindle becomes the same rotational speed as the main spindle. A synchronous rotation control method for a motor. 2. A value obtained by multiplying the number of feedback pulses from a position detector attached to the main spindle by a set magnification is output as a movement command for position loop control of a servo motor for driving the sub spindle, and the sub spindle is driven by the main spindle. In the synchronous rotation control method of driving at the same rotation speed as above, when a differential speed rotation command is input, the sub spindle is rotated at the same rotation speed as the main spindle by multiplying the amount of feedback pulse from the position detector by a set magnification. And a movement command value corresponding to the difference speed commanded is added to the movement command value to obtain a target movement command value, which is then commanded to the servo motor until the target movement command value is reached. The value is incremented or decremented sequentially, and when the target movement command value is reached, the value obtained by multiplying the number of feedback pulses from the position detector by the set magnification and adding the movement command value corresponding to the differential speed Is output as a movement command value of the servomotor, and control is performed such that the rotation speeds of the sub-main shaft and the main main shaft rotate at the command differential speed.