JPH03142602A - Numerical controller - Google Patents

Abstract

PURPOSE:To attain the accurate transfer of a workpiece with use of an auxiliary device by providing a means which discriminates that the workpiece is pressed to a workpiece holding means of its receiver with comparison with the pressing torque value. CONSTITUTION:For instance, a current/torque conversion part 23 detects the load current of a servo motor 20 and calculates the real torque value of the motor 20 while a right spindle 2 is approaching to a left spindle 1. This calculated torque value is averaged for each sampling action and stored in a torque average value memory 27. A real torque computing part 26 subtracts the value obtained by averaging the real torques of the motor 20 obtained from the past sampling actions from the real torque of the motor 20. A torque value comparing part 25 compares the value obtained from subtraction, i.e., the pressing real torque value with the pressing torque set value. When the prescribed conditions are satisfied through the comparison, the part 25 sends a servo system axis shift stop command to a virtual target position generating part 14. Thus it is possible to obtain the optimum pressing force at stable transfer of a workpiece and to transfer the workpiece between spindles with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a numerical control device, and particularly to a numerical control device for numerically controlling workpiece transfer between spindles in which at least one of a plurality of spindles is movable. Regarding a control device.

(Prior art) Fig. 4 shows an opposing 2
FIG. 3 is a diagram showing an operation when a workpiece is transferred from one spindle to the other spindle in a spindle machine. Below, a procedure for performing such an operation in a conventional numerical control device will be explained.

FIG. 5 is a block diagram of a numerical control device in the prior art (Japanese Patent Application No. 63-264395). Conventionally, a program interpreter 13 reads and interprets a program from a program memory 12 (in which a workpiece delivery control program is stored), and first detects a torque limit value command code, and then detects a subsequent torque limit value. is sent to the [dollar cut value→current] conversion unit 24. [Torque limit value - current] conversion unit 24 converts the torque limit value into a torque of the servo system, that is, a current value, and converts the torque limit value into a current value (
torque) limiter 18e. The current (torque) limiter 18 limits the current command value of the servo system from the current (torque) command calculation section 17 to the torque corresponding to the current value when sending it to the power amplification section 19 . Therefore, it becomes possible to limit the thrust of the servo system to a value commanded by the program.

Next, when the program interpreter 13 detects the torque skip command, it sends the pushing torque setting value at which the axis movement should be stopped to the torque value comparison unit 25, and also sends the skip feed command to the virtual target position along with each element data of the program. Generation unit 14
send to The virtual target position generation section 14 sends the target position to the position command calculation section 15, and the position command calculation section 15 generates a function based on it. The speed command calculation unit 16 outputs a speed command based on the function from the position command calculation unit 15 and the detected position from the position detector 21. The current (torque) command calculation unit 17 calculates the output torque of the servo system based on the speed command from the speed command calculation unit 16 and the speed command from the [position → speed] conversion unit 22 based on the detected position from the position detector 21. Output. Therefore, the servo motor 20 rotates to move the upper right shaft 2, which grips the workpiece 5, in the direction of the upper left shaft 1, that is, in the ZΦ force direction. The servo motor 20 continues to rotate even after the end surface of the workpiece 5 reaches the chuck 3 on the left spindle 1 side, but the servo motor rotation axis is mechanically coupled to the right spindle 2 by a ball screw and a saddle. Therefore, the servo motor 2 does not actually rotate.
゜ is in a restrained state. At this time, the servo motor 20 tries to generate the maximum torque that the servo system can produce, but as mentioned above, the output torque is limited by the current (torque) restrictor 18e, so the final programmed torque is Increase in limit value C torque is suppressed. Furthermore, while the right main spindle 2 is approaching the left main spindle 1, the [current-torque] converter 23 detects the load current of the servo motor 20, and uses the detected value as the torque value as the actual torque of the workpiece transfer motor between the main spindles. It is sent to the comparison section 25. The torque value comparison unit 25 compares this delivery motor actual torque with the above-mentioned pressing torque setting value, and when the condition of equation (1) is satisfied, the torque value comparison unit 25 instructs the virtual target position generation unit 14 to stop the servo system axis movement. Send commands.

1 Delivery motor actual torque value 1 ≧ Torque setting value for pressing (1) When the virtual target position generation unit 14 receives the servo system axis movement stop command, it calculates the current position from the position detector 21. It is sent as is to the position command calculation unit 15 as the target position. At this time, the input to the speed command calculation section 16 becomes zero, and the servo motor 20
Since the output torque of the workpiece 5 is reduced, the thrust force applied to the workpiece 5 can be prevented from increasing. In addition, the torque value comparison section 25
sends a servo system axis movement stop command to the virtual target position generation unit 14 and also sends a program skip command to the program interpretation unit 13 to skip the program to the next block.

Next, when the program interpreter 13 detects the torque limit value cancel code, the torque limit value is canceled, the current (torque) limiter 18 cancels the output torque limiter of the servo system, and all processing ends.

(Problem to be Solved by the Invention) By the way, in the above-mentioned conventional numerical control device, the torque setting value for pressing during transfer between the spindles is fixedly set, so the sliding resistance of the feed shaft of the spindle is If the pressure changes due to temperature, wear of the sliding surface, etc., there is a problem in that the workpiece cannot be transferred with a stable pressing force or the transfer is completed with incomplete seating.

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to prevent changes in sliding torque due to heat and wear of the sliding surfaces when transferring workpieces between multiple spindles. It is an object of the present invention to provide a numerical control device that can stably obtain an optimum pressing force when transferring a workpiece without being affected.

(Means for Solving the Problems) The present invention relates to a numerical control device for numerically controlling workpiece delivery between spindles in which at least one of a plurality of spindles is movable. My goal is,
When the main shaft is sent by the feed mechanism, a detection means detects the torque of the drive motor, and a detection result by the detection means is compared with a preset pressing torque value, so that the workpiece is delivered. This is achieved by comprising a comparison and determination means for determining whether the workpiece has been pressed against the previous workpiece gripping means. Further, a sliding torque value is set in advance as the required torque of the feed shaft motor when feeding the main shaft, the detecting means detects the actual motor torque value actually generated in the drive motor, and the comparing and determining means The pressing is achieved by comparing a value obtained by subtracting the sliding torque value from the motor actual torque value and a torque setting value. Further, the sliding torque value is achieved by sampling the actual torque value of the drive motor during the feeding of the main shaft and successively averaging the values.

(Function) In the present invention, the actual motor torque value of the feed shaft generated when the workpiece is pressed against the spindle is limited so that it does not exceed a predetermined value, and the sliding torque of the feed shaft can be corrected. Therefore, the workpiece can be transferred between the spindles with high accuracy.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

Figures 4 (^) to (D) show the two main axes facing each other.
It is a plan view showing an example of a workpiece delivery operation in a spindle lathe, and the left spindle 1 and the right spindle 2 are structured to be movable in the Z-axis direction as indicated by ZA and ZB, respectively. Chuck 3 is installed on the left spindle 1 and the right spindle 2, respectively.
．． 4 is attached, and in this example, the workpiece 5 is gripped by the chuck 4 on the right main spindle 2 side. Therefore, left main axis 1
With the side fixed, the right main spindle 2 is moved in the ZBΦ direction by the right main spindle feeding servo system, and the workpiece 5 is controlled to be pressed against the chuck 3 on the left main spindle 1 side.

Here, the right spindle feeding servo system moves the upper right spindle 2 to ZBΦ even after the workpiece 5 reaches the chuck 3 of the left spindle.
In order to move the workpiece 5 further in the direction, the workpiece 5 is pressed against the chuck 3 on the left main spindle l side, and the torque generated by the right main spindle feeding servo system increases rapidly. Therefore, when the generated torque is detected and the actual delivery torque value, which is obtained by subtracting the preset sliding torque value, reaches the pressing torque setting value, the feeding of the right main shaft 2 in the ZBΦ direction is stopped and the program is executed. Ends execution of the block.

In addition, the torque generated on the feed shaft at regular intervals during the transfer operation is detected and successively averaged, and the actual sliding torque value is averaged by sampling from the current actual torque value of the feed shaft servo motor. When the value obtained by subtracting the value reaches the pressing torque setting value, the feeding of the right main shaft 2 in the ZBΦ direction is stopped and the execution of the block is completed. Hereinafter, the fact that the motor actual torque value reaches the torque setting value and the execution of the program block ends is hereinafter referred to as torque skip.

FIG. 1 is a block diagram of a feed axis servo system in one embodiment of the numerical control device of the present invention, in which part A is the part related to the present invention, and the other parts are the same general servo system as before. be.

An example of this operation will be explained below based on the flowchart of FIG. 2 and the program example of FIG. 3. Regarding the program in Figure 3, specify the right main axis for gripping the workpiece in G14, set the torque limit value of the z-axis in G29, and
A torque skip command is issued at 22, and the torque limit value set at 028 is canceled. Next, in FIG. 2, the program interpreter 13 reads out and interprets the program having such a configuration from the program memory 12, and upon detecting the torque limit value designation code G29, sets the following torque limit value to [torque limit value - current] is sent to the converter 24 (step St). [Torque limit value-current] converter 24 converts the torque limit value into a torque of the servo system, that is, a current value, and sends it to the current (torque) limiter 18. When the current (torque) limiter 18 sends the current command value of the servo system from the current (torque) command calculating section 17 to the power amplifying section 19, the current (torque) limiter 18 limits the torque to the torque corresponding to the current value. Therefore, it becomes possible to limit the thrust of the servo system to the value commanded by the program (step S2).

Next, the program interpreter 13 issues a torque skip command G2.
2 is detected (step S3), the torque setting value for pressing to stop the axis movement is sent to the torque value comparison section 25 (step S4). In addition, the virtual target position generation unit 14 also sends a skip feed command together with each element data of the program.
send to The virtual target position generation unit 14 sends the target position to the position command calculation unit 15, and the position command calculation unit 15 generates a function based on it (step S6).The speed command calculation unit 16 receives the target position from the position command calculation unit 15. Function and position detector 2
A speed command is output based on the detected position from 1. The current (torque) command calculation unit 17 calculates [
[Position→Velocity] The output torque of the servo system is output based on the speed command from the converter 22. As a result, the servo motor 20 rotates in an attempt to move the upper right shaft 2, which grips the workpiece, in the direction of the left main shaft 1, that is, in the ZB direction. The servo motor 20 continues to rotate even after the end surface of the workpiece 5 reaches the chuck 3 on the left spindle 1 side.
Since the servo motor rotation shaft is mechanically coupled to the right main shaft 2 by a ball screw and a saddle, it does not actually rotate and the servo motor 20 is in a restrained state. At this time, the servo motor 20 tries to generate the maximum torque that the servo system can produce, but as mentioned above, the output torque is limited by the current (torque) limiter 18, so the torque limit set by the program is finally set. Torque increase is suppressed to this value. Also, while the right main shaft 2 approaches the left main shaft 1, the [current-torque] converter 23 detects the load current of the servo motor 20, calculates the servo motor actual torque value, samples the values, and averages them. and stored in the torque average value memory 27 (step S9). The actual torque calculation section 26 subtracts a value obtained by averaging the servo motor actual torque obtained by past sampling (actual sliding torque value) from the actual torque value of the servo motor 20, and the obtained value is subtracted from the actual torque value of the servo motor 20. (step 57). Torque value comparison section 25
is the difference between this motor actual torque value and the actual sliding torque value, that is, the actual torque value for pressing and the previously mentioned torque setting value for pressing. Then, a servo system axis movement stop command is sent to the virtual target position generation unit 14.

1 Pressing is the actual torque value l ≧ Pressing is the torque setting value...
・(2) Virtual target position generation unit! 4 receives the servo system axis movement stop command, and sends the current position from the position detector 21 as it is to the position command calculation unit 15 as the target position (step 510). At this time, the input to the speed command calculation unit 16 becomes zero, and the output torque of the servo motor 20 is reduced, so that the thrust against the workpiece 5 can be prevented from increasing. Further, the torque value comparison unit 25 sends a servo system axis movement stop command to the virtual target position generation unit 14 and a program skip command to the program interpretation unit 13.
Skips the program to the next block (step 5)
ll).

Next, when the program interpreter 13 detects the torque limit value cancel code G28, the torque limit value is canceled and the current (torque) limiter 18 cancels the output torque limiter of the servo system.Step 512
), - End all processing.

In the above-mentioned embodiment, the right main spindle C of the two-spindle lathe is
We explained the control in which the workpiece gripped by the chuck attached to the left spindle is transferred to the chuck attached to the left spindle by the right spindle servo system. This can also be used when transferring to a chuck attached to the right spindle. Further, the present invention can be applied to a lathe with a sub-spindle called a sub-spindle, a lathe with a tool rest equipped with a device called a pick-off chuck, and the like.

In the above explanation, sliding torque is used as the required torque of the feed shaft motor when feeding the main shaft, but resistance against feeding other than sliding resistance and feeding torque of a feeding mechanism without a sliding mechanism are used. It is clear that the same method can be used to correct the problem.

(Effects of the Invention) As described above, according to the numerical control device of the present invention, it is possible to accurately transfer workpieces without using auxiliary devices such as workpiece butchers, so products with high processing accuracy can be quickly delivered. can be provided to

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a numerical control device of the present invention, FIG. 2 is a flowchart showing the operating procedure of the present invention, FIG. 3 is a program example for explaining the present invention, and FIGS. 4 (A) to (D)
5 is a diagram for explaining the transfer of workpieces, and FIG. 5 is a block diagram of a conventional numerical control device. 1...Left spindle, 2...Right spindle, 3.4...Chuck, 5...Workpiece, 12...Program memory, 1
3... Program interpretation section, 14... Virtual target position generation section, 15... Position command calculation section, 16... Speed command calculation section, 17... Current (torque) command calculation section, 18.
...Current (torque) limiter, 19...Power amplification unit, 20...Servo motor, 21...Position detector, 2
2...[Position→Speed] converting section, 23...[Current→torque value] converting section, 24...[Doctor value→current] converting section, 25...Torque value comparing section, 26...Actual torque calculation section, 27...Torque average value memory, 2B...
・Torque average value calculation section.

Claims (1)

[Scope of Claims] 1. In a numerical control device that numerically controls a workpiece gripping means and a plurality of spindles each having a feeding mechanism, at least one of which is provided, the workpiece is held on the workpiece gripping means between the spindles. When transferring the workpiece, when the main shaft is sent by the feed mechanism, a detection means detects the torque of the drive motor, and a detection result by the detection means is compared with a preset pressing torque value. A numerical control device characterized by comprising a comparison and determination means for determining whether the workpiece is pressed against the workpiece gripping means of the delivery destination. 2. A feed torque value is set in advance as the required torque of the feed shaft motor when feeding the main shaft, the detection means detects the actual motor torque value actually generated in the drive motor, and the comparison and determination means detects the motor torque value actually generated in the drive motor. The numerical control device according to claim 1, wherein a value obtained by subtracting the feed torque value from a motor actual torque value is compared with the pressing torque setting value. 3. The numerical control device according to claim 2, wherein the feed torque value is obtained by sampling the actual torque value of the drive motor during feeding of the spindle and successively averaging the values.