JPH03219306A - Method for controlling feeding speed of numerical controller - Google Patents

Abstract

PURPOSE:To attain highly accurate working having a small time constant and reducing its error at the time of using pre-interpolation acceleration/deceleration (pre-IAD) and to attain smooth and rapid working having a large time constant when the pre-IAD is not used by switching the time constant of post- interpolation acceleration/deceleration (post-IAD) in accordance with the used/ unused state of the pre-IAD. CONSTITUTION:The time constant of post-IAD at the time of using the pre-IAD and that at the time of no use of the pre-IAD are respectively set up to different values. Namely, a pre-IAD circuit 3 executes acceleration/deceleration by a fixed time constant based upon a pre-IAD starting command and ends the pre- IAD operation based upon a pre-IAD end command. An interpolation means 4 distributes pulses to respective axes based upon data outputted from a preprocessing arithmetic circuit 2 and a constant switching circuit 5 switches the time constant in accordance with the used/unused state of the pre-IAD selected by an A/D start command or an A/D end command. Consequently, the time constant of post-IAD can be switched to differently set time constant.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling the feed rate of a numerical control device, and particularly to a feed rate control method for a numerical control device that improves the interaction between acceleration/deceleration before interpolation and acceleration/deceleration after interpolation. This invention relates to a speed control method.

[Conventional technology]

In a numerical control unit (CNC), the program is processed (preprocessed) in advance in a form that is easy to execute block by block, and distributed (executed) based on the data. In such a CNC, post-interpolation acceleration/deceleration is normally performed to blunt distribution data after interpolation with a certain time constant in order to prevent shocks to the machine due to sudden speed changes. When using acceleration/deceleration after interpolation, machining errors occur, but since acceleration/deceleration is performed for each axis at the corner, machining can be performed smoothly without any particular deceleration.

In contrast, pre-interpolation acceleration/deceleration has been developed and put into practical use in order to solve the problem of machining errors, which is a drawback of post-interpolation acceleration/deceleration. This pre-interpolation acceleration/deceleration has the advantage of not causing machining errors because it applies acceleration/deceleration to the feed rate in the tangential direction, but on the other hand, when looking at each axis at corners, rapid speed changes occur, so it is automatically Since a deceleration function etc. must be used, there is a drawback that the cycle time becomes longer by the amount of deceleration.

In addition, acceleration and deceleration is performed for each axis at the corner, and when using both the post-interpolation deceleration, which allows smooth machining without particularly decelerating, and the pre-interpolation dynamic deceleration, which gradually changes the feed speed in the tangential direction. There is also.

[Problems to be solved by the invention] However, in the conventional method of controlling the feed rate of a numerical control device,
The same time constant for post-interpolation deceleration was used whether or not pre-interpolation dynamic deceleration was used. Therefore, if the time constant of the post-interpolation deceleration is set small with emphasis on accuracy when using the pre-interpolation dynamic deceleration, the shock to the machine will be large if the pre-interpolation dynamic deceleration is not used. Conversely, if the time constant of the post-interpolation deceleration is set large so that acceleration/deceleration is sufficiently smooth when pre-interpolation acceleration/deceleration is not used, highly accurate machining can be performed even when pre-interpolation dynamic deceleration is used. The problem is that it disappears.

The present invention has been made in view of these points, and provides a feed rate control method for a numerical control device that switches the time constant of the post-interpolation deceleration to a separately set time constant depending on whether or not the pre-interpolation acceleration/deceleration is used. The purpose is to provide

[Means to solve the problem]

In order to solve the above-mentioned problems, in the present invention, in the feed rate control method of a numerical control device, the time constant of the post-interpolation deceleration when the pre-interpolation dynamic deceleration is used and the time constant of the post-interpolation deceleration when the pre-interpolation dynamic deceleration is not used. A method for controlling the feed rate of a numerical control device is provided, which is characterized in that the time constant of monthly deceleration is set to different values.

[Effect]

If pre-interpolation acceleration/deceleration is commanded by the program or parameter, the time constant for post-interpolation monthly deceleration is switched to a time constant set separately from the normal post-interpolation monthly deceleration time constant. Furthermore, if pre-interpolation dynamic deceleration is not commanded, the time constant is switched to the normal post-interpolation deceleration.

〔Example〕

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

FIG. 2 is a block diagram showing the configuration of a numerical control device in an embodiment of the present invention. 1 is an NC program, which is created by a numerical control device. Reference numeral 2 denotes a preprocessing arithmetic circuit, which preprocesses the addition program into a form that is easy to execute block by block. 3 is a pre-interpolation acceleration/deceleration circuit, which accelerates/decelerates the feed speed in the tangential direction in order to prevent shock to the machine due to rapid speed changes. In addition, the pre-interpolation original deceleration start command (GO5, IQl)
Accordingly, the pre-interpolation acceleration/deceleration circuit 3 accelerates/decelerates with a predetermined time constant, and receives the pre-interpolation acceleration/deceleration end command (G).

5, IQO), the pre-interpolation dynamic deceleration operation ends.

4 is an interpolation means, which distributes pulses to each axis based on data from the preprocessing calculation circuit 2.

5 is a time constant switching circuit, which switches the time constant of the post-interpolation acceleration/deceleration circuit described next. This time constant switching circuit 5 is
The acceleration/deceleration start command (
GO5, 1QI) and acceleration/deceleration end command (QO5, IQO)
The time constant is switched depending on whether or not pre-interpolation dynamic deceleration is used, which is selected by a command such as Reference numeral 6 denotes a post-interpolation acceleration/deceleration circuit, which blunts the distributed data after interpolation with a certain time constant and applies acceleration/deceleration to each axis in order to prevent shock to the machine due to rapid speed changes. 7x and 7Y are axis control circuits, where X is assumed to be the X axis and Y is assumed to be the Y axis. Similarly, 8X and 8Y are servo amplifiers, and 9x and 9Y are servo motors.

FIG. 3 shows a numerical control device (CNC) for implementing the present invention.
) is a block diagram of the hardware.

The processor 11 controls the entire numerical control device according to a system program stored in the ROM 12. ROM
12 is an EPROM or an EEPROM. An SRAM is used as the RAM 13, and various data are stored therein. The non-volatile memory 14 is a program 14a.
Since the CMO 8 and the like with battery backup are used, the contents are retained even after the numerical control device is powered off.

PMC (7' programmable machine controller) 1
5 receives commands for the M function, S function, T function, etc., and decodes and processes these commands using the sequence program 15a.
Outputs output signals to control machine tools. In addition, in response to limit switch signals from the machine side or switch signals from the machine operation panel, the sequence program 15
a Te processing and output an output signal to control the machine side,
Signals necessary for the numerical control device are sent to the RAM via bus 25.
13 and read by the processor 11.

The graphic control circuit 16 converts data stored in the RAM 13, such as the current position and amount of movement of each axis, into display signals.
It is sent to the display device 16a, and the display device 16a displays it. As the display device 16a, a CRT1 liquid crystal display device or the like is used. The keyboard 17 is used to input various data.

The axis control circuit 18 receives a position command from the processor 11 and outputs a speed command signal for controlling the servo motor 20 to the servo amplifier 19. The servo amplifier 19 amplifies this speed command signal and drives the servo motor 20. A pulse coder 21 that outputs a position feedback signal is coupled to the servo motor 20. The pulse coder 21 feeds back position feedback pulses to the axis control circuit 18. In addition to the pulse coder 21, a position detector such as a linear scale may be used. These elements are required for the number of axes, but since the configuration of each element is the same, only one axis is shown here.

The input/output circuit 22 exchanges input/output signals with the machine side.

That is, the PMC 15 receives limit switch signals from the machine side and switch signals from the machine operation panel, and reads these signals. It also receives an output signal from the PMC 15 for controlling a pneumatic actuator, etc. on the machine side, and outputs it to the machine side.

The manual pulse generator 23 outputs a pulse train for precisely moving each axis according to the rotation angle, and is used to precisely position the machine. Manual pulse generator 23 is usually mounted on a machine operation panel.

In the figure, the spindle system 'f1 to control the spindle
The circuit, spindle amplifier, spindle motor, etc. are omitted.

Further, although there is one processor here, a multi-processor system using a plurality of processors can be used depending on the system.

FIG. 1 is a flowchart of a feed rate control method according to an embodiment of the present invention. In the figure, the number following S indicates the number of steps.

[S1] Check whether pre-interpolation acceleration/deceleration is in use (mode). If it is in use, proceed to S2; if not, proceed to S5.

[S2] Check whether there is a command to end the use of pre-interpolation acceleration/deceleration, and if there is a command to end the use, proceed to S3.

[S3] Since the pre-interpolation acceleration/deceleration has been changed from being in use to being used, in order to eliminate the error caused by the accumulation of pulses in the post-interpolation acceleration/deceleration, the deceleration is completed until the accumulated pulses in the post-interpolation deceleration circuit become 0. Perform an exact stop check.

[S4] The time constant of the post-interpolation acceleration/deceleration that was suitable when the pre-interpolation acceleration/deceleration was used is switched to a large value so that it is suitable when the pre-interpolation acceleration/deceleration is not used.

[S5] Check whether there is a command to start using pre-interpolation acceleration/deceleration, and if there is a command to start using it, proceed to S6.

[S6] Since the acceleration/deceleration before interpolation has been changed from not being used to being used, in order to eliminate the error caused by the accumulation of pulses in the acceleration/deceleration after interpolation, the accumulation of pulses in the post-interpolation deceleration circuit is
Perform an exact stop check to completely decelerate until .

[S7] The time constant of the post-interpolation acceleration/deceleration that is suitable when the pre-interpolation acceleration/deceleration is not used is changed to a small value so that it is suitable when the pre-interpolation acceleration/deceleration is used.

〔Effect of the invention〕

As explained above, in the feed rate control method of the present invention, the time constant of post-interpolation acceleration/deceleration is switched to an appropriate value depending on whether or not pre-interpolation acceleration/deceleration is used. can perform high-precision machining with few errors with a small time constant, and when pre-interpolation acceleration/deceleration is not used, smooth and high-speed machining can be performed with a large time constant.

[Brief explanation of drawings]

FIG. 1 is a flowchart of a feed rate control method according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a numerical control device according to an embodiment of the present invention, and FIG. 3 is a flow chart for implementing the present invention. Numerical control device (CNC)
) is a block diagram of the hardware. 7 X, 7 Y 8 X, 8 Y 9 AM Non-volatile memory programmable controller PMC (programmable master controller) Sequence program display device Keyboard axis control circuit Servo amplifier Servo motor Pulse coder I/O circuit Manual pulse generator Nox

Claims (3)

[Claims] (1) In the feed rate control method of the numerical control device, the time constant for acceleration/deceleration after interpolation when using acceleration/deceleration before interpolation is different from the time constant for acceleration/deceleration after interpolation when acceleration/deceleration before interpolation is not used. A feed rate control method for a numerical control device, characterized in that the feed rate is set to a value. 2. The feed rate control method for a numerical control device according to claim 1, wherein the time constant of the post-interpolation acceleration/deceleration is automatically switched depending on whether or not the pre-interpolation acceleration/deceleration is used. (3) The feed rate control method for a numerical control device according to claim 1, wherein the time constant of the post-interpolation acceleration/deceleration is selected by a parameter.