JPH03131905A - Synchronizing operation device for machine tool - Google Patents

Abstract

PURPOSE:To prevent a slave side from running away due to the separation of a work by judging asynchronism between a main spindle and a subspindle and the reduction of a torque command as work separation and switching the control of the sub-spindle of a slave side from torque control to speed control. CONSTITUTION:When the main spindle is connected to the sub-spindle through a work and the work is separated from its synchronizing operation state, the torque is reduced and a torque command from a speed controller 11 arranged on the master side 1 is reduced. When the torque command is inputted to a torque detector 6E, positional synchronism between both the main and sub- spindles is destroyed. The positional asynchronism is judged by a positional deviation detecting part 6F based upon signals outputted from pulse encoders 5, 5A of the main spindle and the sub-spindle. The outputs of the detecting parts 6E, 6F are inputted to an AND gate 6G, and when a torque changing value and a position or speed deviation are larger than respective set values, the result is transmitted to a logic part 6H. Since the logic part 6H opens a switch 6D and invalidates torque control, the slave side can be prevented from running away due to separation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention has two drive systems, and when they are connected via a rigid body such as a workpiece, they operate in synchronization with each other. This invention relates to a synchronous operation device for a machine tool in which rigid bodies are separated simultaneously.

[Conventional technology]

In machine tools, a main spindle and a sub-spindle are connected via a workpiece and operate synchronously, and the workpiece may be separated while being synchronously controlled. When synchronizing two drive systems connected by a rigid body such as a workpiece, one is usually used as a master to control speed, and the other is used as a slave to control torque. Therefore, if a workpiece is to be separated under synchronous control, there is a risk that the slave side will go out of control unless some measure is taken.

For this reason, in conventional synchronous operation devices, a torque limiter is provided for torque control on the slave side to prevent instantaneous runaway, and on the other hand, the position of the cutting tool (processing machine) that separates the workpiece is detected, and the workpiece is separated depending on the position. It was determined that this was the case, and countermeasures were taken, such as stopping the slave side or switching synchronous control to speed control for both axes.

[Problem to be solved by the invention]

To detect separation of a workpiece using conventional equipment, the NC (numerical control unit) side of the machine tool must monitor the feed distance of the cutter, etc., and detect when the cutting edge of the cutter has come to the center of the workpiece. The burden on people increases. Further, in some cases, the workpiece may be threaded before the cutting edge of the cutter reaches the center of the workpiece due to torque imbalance between the main spindle and the sub-spindle. In this case, in a system that detects separation of the workpiece based on the feed distance of the cutter, there will be a delay in detection compared to the actual separation of the workpiece, and due to this delay, the slave side will be affected by the torque limiter in the worst case, but only by the amount of the delay time. It will go out of control.

Therefore, an object of the present invention is to enable accurate detection of separation of a workpiece and to prevent runaway on the slave side due to separation of the workpiece.

[Means to solve the problem]

a main spindle driven by a first inverter device that performs speed control; a sub spindle driven by a second inverter device that performs speed control; a first detection means that detects a change in torque of the main spindle; A second detection means for detecting a deviation in position or speed between the main spindle and the sub spindle, and when the main spindle and the sub spindle are operated synchronously via a workpiece to be machined, the second detection means detects a deviation in position or speed between the main spindle and the sub spindle. Position control is performed to control the positions of the sub-spindles so as to match each other, and torque control is performed to control the torque balance between the main spindle and the sub-spindle, and the amount of change in torque detected by the first output means and A controller is provided that disables torque control on the sub-spindle side when the position or speed deviation detected by the second detection means exceeds a predetermined set value, respectively.

[Effect]

If the workpiece is separated while the main spindle is still under speed control and the sub-spindle is under torque control, not only will the main spindle and sub-spindle become out of synchronization, but the required torque will rapidly decrease due to no load. Therefore, when the synchronization relationship deviates and the torque command decreases to a certain extent, it is determined that the workpiece has been separated, and based on the result of this determination, the control of the sub-spindle on the slave side is switched from torque control to speed control.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the invention.

In this embodiment, a speed regulator (ASR) 11, a vector calculation unit 12, and a switching element 13 are used to construct a null inverter device 1, a main spindle motor 2 driven by this inverter 1, and a speed detection device for this motor 2. The master side consists of a pulse encoder 3 , a main spindle 4 mechanically connected to the motor 2 , and a pulse encoder 5 that detects the speed and position of the main spindle 4 , as well as an ASR 11 and a vector calculation section 12 . and switching element 1
Inverter device 1A consisting of 3 and this inverter I
A sub-spindle motor 2A driven by A, a pulse encoder 3A for detecting the speed of this motor 2A, a sub-spindle 4A mechanically coupled to the motor 2A, and a sub-spindle motor 2A that detects the speed and position of this sub-spindle 4A. a slave side consisting of a pulse encoder 5A for detection; a position adjuster (APR) 6A for controlling the positions of the master side and the slave side;
A synchronous controller 6 consisting of a torque regulator (ATR) 6B that controls the torque balance between the master side and the slave side, and switches 6C and 6D that switch control.
It is composed of.

Here, the inverter device 1.1A is the synchronous controller 6
The ASRII
operate and perform speed control. Also, ASRII
The torque command, which is the output of
By applying a predetermined voltage and current to the motor 4.4
A and the speed to motor 4.4 is controlled.

During normal synchronous operation, the switch 6C is closed and the position signal from the pulse encoder 5 detects the position of the main spindle.
The APR 6A operates according to the position signal of the pulse encoder 5A that detects the position of the sub-spindle, and the output of the APR 6A is added to the speed command on the master side, which becomes the speed command given to the inverter device IA on the slave side. and,
When the main ball spindle 4 and the sub-spindle 4A are connected by a workpiece, the positional deviation between the main spindle 4 and the sub-spindle 4A becomes zero, and the output of the APR 6A also becomes zero.

Therefore, the switch 6D is closed and the inverter device is 1°lA.
If the torque I command of the output of ASRII is input to the synchronous controller ATR6B, the main spindle 4 and sub spindle 4
Since the ATR 6B operates to maintain the torque balance of A, a correction is added to the speed command on the slave side.

FIG. 2 shows a specific example of a control circuit for controlling on/off of the switch 6D in the synchronous controller. In the figure, 6E is a torque detection section, 6F is a position (speed) deviation detection section, 6G is an AND gate, 6H is a switch 6D turned on,
This is a logic section that performs off control.

Now, when the main spindle 4 and the sub-spindle 4A are connected by a workpiece and the workpiece is separated from the state in which synchronous operation is being performed, the required torque is reduced because the processing machine such as a cutter is not biting into the workpiece. The torque command, which is the output of ASRII on the master side, decreases. This torque command is input to the torque detector 6, and the amount of change in torque is detected, for example, from the difference between the previous value and the current value of the torque command value, and if this exceeds a predetermined set value, a high level output is output. Make it. In addition, even if the workpiece is separated, the slave side performs torque control, so the main spindle 4 and the sub spindle 4A
The position (velocity) synchronization relationship with the This deviation in position synchronization is determined by the position deviation detection section 6F based on the signals from the pulse encoder 5 of the main spindle 4 and the pulse encoder 5A of the sub spindle 4A. That is, the position or speed deviation is compared with a predetermined set value, and if the deviation exceeds the set value, a high level output is output. The outputs of the torque detecting section 6E and the position deviation detecting section 6F are input to the AND gate 6G, and when this is established, that is, when the amount of change in torque and the position or speed deviation are both larger than the set value, a logic section 6H indicates that this is true. can be conveyed to. As a result, the logic section 6) opens the switch 6D and disables the torque control.

〔Effect of the invention〕

According to this invention, the separation of the workpiece is determined on the synchronous controller side based on the change in torque and the synchronous position or speed, so detection with less delay is possible and the burden on the NC can be reduced. Furthermore, since the slave side is switched from torque control to speed control based on the judgment of workpiece separation, it is independent of the constants of APR and ATR, and the risk of runaway can be eliminated. Furthermore, if the constants (gains) of APR and ATR are selected so that the ATR correction amount is larger than the APR correction amount, and the above switching is not performed, the position adjustment will become ineffective and runaway will occur. Sometimes.

Furthermore, since the separation of the workpiece is detected from the torque change and the synchronized position or speed, even if machining is stopped midway or the synchronization is lost due to insufficient chucking (gripping) pressure on the workpiece, an error will occur. It also has the advantage of not being detected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a specific example of an on/off control circuit. Symbol explanation 1, IA... Inverter device, 2.2A... Motor, 3.3A... Pulse encoder for motor, 4...
Main spindle, 4A...Sub spindle, 5,5A...Pulse encoder for main spindle, 6...Synchronization controller, 6
A...Position regulator (APR), 6B...Torque regulator (ATR), 6C, 6D...Switch, 6E...
・・Torque detector, 6F・Position deviation detector, 6G・
...AND gate, 6H...logic section, 11...
Speed regulator (ASR), 12...vector calculation unit, 1
3...Switching element.

Claims (1)

[Claims] 1) A main spindle driven by a first inverter device that performs speed control, a sub spindle driven by a second inverter device that performs speed control, and detecting changes in torque of the main spindle. a first detection means for detecting a deviation in position or speed between the main spindle and the sub-spindle; and a second detection means for detecting a deviation in position or speed between the main spindle and the sub-spindle; In this case, position control is performed to make the position of the main spindle and the position of the sub spindle coincide with each other, and torque control is performed to control the torque balance between the main spindle and the sub spindle, and the detection is performed by the first detection means. a controller that disables torque control on the sub-spindle side when the amount of change in torque detected by the controller and the position or speed deviation detected by the second detection means each exceed a predetermined set value. Machine synchronous operation device.