JPH03186903A - Positioning control system - Google Patents

Abstract

PURPOSE:To simplify a work program by abutting a feed shaft on a mechanical stopper in a state where a torque limit is applied to the servo of the feed shaft so as to attain positioning, obtaining a position deviation quantity from the shift stop of the feed shaft and the exciting current of the servo and deciding positioning when the value exceeds a prescribed value. CONSTITUTION:When the feed shaft is abutted on the mechanical stopper, the shift of the shaft is stopped and the exciting current of a servo motor 44 continuously flows, the position deviation quantity of an error register increases. When it is detected that the value comes to more than the prescribed value, a clamping command is outputted and the clamping command is outputted to a machine-side trough a DI/DO 38. Thus, a clamping device is operated and the shaft is fixed. Thus, the feed shaft is abutted on the mechanical part and a time when the position deviation quantity of the feed shaft exceeds the prescribed value is assumed to be the completion of positioning. Thus, the positioning control of the shaft in a numerically controlled machine executing a clamping operation can easily be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning control system, and particularly to a positioning control system in which positioning is performed by abutting a shaft against a mechanism in a numerically controlled machine tool.

[Conventional technology]

One method for controlling the positioning of an axis in a numerically controlled machine tool is to place a torque limit on the servo motor of the feed axis and position the axis by abutting the feed axis against a stopper. If the workpiece is machined in this state, the position will change due to the reaction force and the machining accuracy will decrease. As a means to prevent this, methods such as mechanically clamping the control axis of the CNC before machining are used.

For example, in a transfer machine processing machine, positioning was programmed as follows.

That is, the feed shaft is programmed to move beyond the position determined by the mechanical stopper, and positioning is performed with the torque limit enabled. After the distribution command of this program block is completed, the next clamp command is read, and the clamp command of the control axis is output. In this way, the programmer programs the control operations of one related machine while considering each operation as a control sequence.

[Problem to be solved by the invention]

However, in the conventional axis positioning control method for numerically controlled machine tools, one machine operation is controlled in sequence, so it is necessary to always program clamp commands. Further, there is a problem in that time is wasted until the over-excess pulse distribution is completed.

The present invention has been made in view of these points, and the present invention is based on a numerical value at which the clamping operation is performed, with the feed shaft abutted against the mechanical part, positioning being considered complete when the position deviation amount of the feed shaft exceeds a certain value. The purpose of this paper is to provide a system for controlling the positioning of axes in controlled machine tools.

[Means to solve the problem]

In order to solve the above problems, the present invention uses a positioning control method in which a numerically controlled machine tool abuts a shaft against a mechanical section to perform positioning, puts the shaft in a torque limit state, abuts the shaft against the mechanical section, A positioning control method is provided, in which positioning is regarded as complete when the positional deviation amount of the shaft exceeds a certain amount, and a clamp command for the shaft is output to clamp the shaft.

[Effect]

In the axis positioning control method of numerically controlled machine tools,
Apply a torque limit to the feed axis servo that performs positioning. Move the feed shaft and hit the mechanical stopper. Positioning is completed when the positional deviation of the feed axis exceeds a certain value while the torque limit is applied. This timing is detected and a clamp command is output to fix the feed axis.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Figure 3 shows a single-axis numerical control device (C
FIG. 2 is a block diagram of the hardware of the NC. In the figure, 30 is a single-axis numerical control device (CNC). The processor 31 is a central processor for controlling the entire single-axis numerical control device (CNC) 30, and is connected to the RO via the bus 51.
The system program stored in M32 is read out, and the one-axis numerical control device (C
NC) Executes overall control of 30. An arbiter (arbitration circuit) 33 arbitrates between the bus 51 and the bus 52. CMO
3RAM35 stores tool compensation values, pitch error compensation amounts, cutting programs, parameters, and PMC (7” programmable
Machine/controller ladder program etc. are stored. This CMO3RAM 35 is backed up by a battery 36 and serves as a non-volatile memory even when the single-axis numerical controller (CNC) 30 is powered off, so its data is retained as is.

The machine side is controlled by a sequence program created in the PMC ladder format stored in the CMO3RAM35.

That is, according to the M function, S function, and T function commanded by the machine program, these are converted into necessary signals on the machine side by the sequence program, and the DI/D○ unit 3
Output from 8 to the machine side. This output signal drives a magnet, etc. on the machine side, and operates a hydraulic valve, a pneumatic valve, an electric actuator, etc. In addition, it receives signals from limit switches on the machine side, switches on the machine operation panel, etc.
Do the necessary processing. The 5LC37 performs serial communication with other control devices under the control of the CPU31.

A DSP (digital signal processor) 41 is a processor that plays a central role in axis control, reads out a servo control program stored in a ROM 42 via a bus 52, and executes overall control of the axis control in accordance with this control program. . The axis control circuit 43 receives the axis movement command from the DSP/11 and outputs the axis movement command to the servo amplifier 44. Upon receiving this movement command, the servo amplifier 44
The servo motor 45 of the shaft is driven. The servo motor 45 is provided with a torque limiter and has a built-in pulse cog 4G for detecting position data. This position feedback pulse is fed back to the pulse cog 46. The difference between the axis movement command value and the position feedback pulse from the pulse cog 46 is stored in an error register (not shown) in the axis control circuit 43 as a position deviation amount.

When the feed axis hits a mechanical stopper, the movement of the axis is stopped, and the excitation current of the servo motor 44 continues to flow, the position deviation amount of the error register increases, and when it is detected that this value has exceeded a certain value. , outputs a clamp command,
A clamp command is output to the machine side via DI/D038 to operate the clamp mechanism and fix the shaft.

After the axis is fixed, the position deviation amount in the error register is followed up, and the excitation current of the servo motor 44 is turned off. These commands are output from the CPU 31 and DSP 41.

FIG. 2 is an explanatory diagram of an axis positioning control system in a numerically controlled machine tool according to an embodiment of the present invention.

In the figure, a 1-axis numerical control device (CNC) AIO controls a turret slide unit 11 and a clamp mechanism 12. The mechanical stopper 13 defines the limit of movement of the tool post slide unit 11 to the right and is a reference for the movement position. A single-axis numerical control device (CNC) B20 controls a traverse shaft 21, and a workpiece 22 is jacked to the traverse shaft 21 and reciprocates in the direction of the arrow. Further, this tool post slide unit 11 has a built-in moving mechanism.

The respective functions will be explained assuming that a workpiece 22 that has been placed on the traverse shaft 21 is milled using the tool of the tool post slide unit 11.

Turret slide unit 1 as a condition for precision machining
It is necessary to prevent fluctuations of 1. ■Axis numerical control device (C
NC) The servo motor is driven by the movement command from A1.0, and the tool post slide unit 11 abuts against the mechanical stopper 13. This abutment is caused by a torque limiter and the force is below a certain value. Although the tool post slide unit 11 hits the mechanical stopper 13 and stops moving, the excitation current continues to flow through the servo motor, so the amount of positional deviation is accumulated. When the positional deviation amount exceeds a certain value, it is determined that the tool post slide unit 11 has accurately abutted against the mechanical stopper 13 and the position has been determined. 1
In response to a clamp command from the axis control device (CNC) A 10, the clamp mechanism 12 is operated and the tool post slide unit 11 is firmly fixed. In the figure, the imaginary dashed line indicates the turret slide unit) 11 indicates the mechanical stopper 13
The positioning is completed when it hits the clamp mechanism 1.
2 shows the state in which the tool rest slide unit) 11 is fixed.

After clamping (fixing) the turret slide unit 1,
The axis numerical control device (CNC) AIO performs follow-up processing to cancel the positional deviation because the amount of positional deviation of the axis to which the torque limit has been applied is large. Also, turn off the excitation of the servo motor. After that, the single-axis numerical control device (CNC) B2 that controls the traverse axis 21
Outputs the turret machining preparation completion signal to 0.

A single-axis numerical control device (CNC) B20 reciprocates the workpiece 22 in the direction of the arrow, and moves the workpiece 22 back and forth in the direction of the arrow.
The workpiece 22 is milled using the tool. After the machining is completed, the clamp is released by reversing the procedure and the tool post slide unit 11 is moved back to the machining start standby position.

FIGS. 1A and 1B are flowcharts of an axis positioning control system in a numerically controlled machine tool according to the present invention.

In the figure, the number following S indicates the step number.

[S1] Read the Canadian program.

0 [S2]) Check to see if there is a limit command M18, and if there is, go to S3; if not, go to S12.

[S3] Send M2S to PMC.

[:S4] PMC decodes M2S.

[:S5. ] Sends the torque limit signal back to the NC.

[56)) Set the value limit.

[S7] Command the servo motor to move the feed axis.

[S8] Check whether the positional deviation amount exceeds a certain value. If it does, go to S9; if not, repeat checking.

[S9] DI the clamp command for the tool post slide unit.
/Output from D○.

rSlo) Fix the turret slide unit.

[511] Follow up the positional deviation amount and turn off the excitation of the servo motor.

[S12]) One-axis numerical control device that controls the rubber axis [(
Start CNC) B and start machining the workpiece.

〔Effect of the invention〕

1. As explained above, in the axis positioning control method of a numerically controlled machine tool, the present invention performs positioning by hitting a mechanical stopper with a torque limit applied to the servo of the feed axis, and moves the feed axis. The positional deviation amount is determined from the stop and servo excitation currents, and when this value exceeds a certain value, the positioning is determined to have been determined, so there is no need to program a clamp command, and the control program is simplified.

Furthermore, there is no need to wait for the pulse distribution of the feed axis, reducing machining time.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are flowcharts of an axis positioning control method in a numerically controlled machine tool according to the present invention, and FIG. 2 is a flowchart of an axis positioning control method in a numerically controlled machine tool according to an embodiment of the present invention. FIG. 3 is a block diagram of the hardware of a single-axis numerical control device (CNC) for implementing the present invention. 2 0 1 2 3 0 1 2 0 3 work 2 3 5 7 8 1 2 3 44゛5 6 1-axis numerical control device (CNC) Turret slide unit clamp mechanism Mechanical stopper 1-axis numerical control device (CNC) Traverse axis Workpiece 1-axis numerical control device (CNC) PU OM Arbiter CMO3RAM LC DI/D○ SP OM Axis control circuit servo amplifier servo motor pulse coder 3 Nox- Nox

Claims (4)

[Claims] (1) In a positioning control method in which positioning is performed by abutting an axis against a mechanical part in a numerically controlled machine tool, the shaft is placed in a torque limit state, the axis is abutted against the mechanical part,
A positioning control method characterized in that when the positional deviation amount of the axis exceeds a certain amount, positioning is regarded as complete, and a clamp command for the axis is output to clamp the axis. (2) After clamping the shaft, the excitation current of the servo motor of the shaft is turned off.
Positioning control method described in section. (3) The positioning control system according to claim 1, wherein after clamping the shaft, a follow-up is performed to eliminate the amount of positional deviation of the shaft. (4) The positioning control method according to claim 1, wherein the positioning control is performed by a single-axis CNC control.