JPH04169907A - Acceleration/deceleration control system - Google Patents

Abstract

PURPOSE:To always execute a working program while overlapping two blocks by detecting the command speed of a tool at the time of acceleration/ deceleration and comparing this speed with a reference speed to command the execution start of the next block. CONSTITUTION:A program executing means 2 executes a working program 1 while overlapping two continuous blocks. An interpolating means 3 distributes pulses of respective shafts based on speed command data outputted from the program executing means 2, and distributed pulses are supplied to an exponential acceleration/deceleration means 4a or/and a linear acceleration/deceleration means 4b. A command speed detecting means 6 detects a command speed FR outputted from the linear acceleration/deceleration means 4b, and an execution start command means 7 compares this speed FR with a reference speed Fx to command the execution start of the next block. Thus, the execution efficiency of the program is not degraded even if blocks of the working program are different in acceleration/deceleration type, and the working time is shortened.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an acceleration/deceleration control method for a numerical control device, and in particular to an acceleration/deceleration control method in which the commanded speed of a tool is accelerated or decelerated linearly or exponentially from a programmed speed. Regarding control method.

[Prior Art] When a tool such as a movable part of a machine tool is moved at high speed, shocks are applied at the start and stop of the movement. In a numerical control device, it is necessary to move the mechanical movable parts smoothly and to guarantee machining accuracy.

Therefore, a method is adopted in which the command speed is accelerated or decelerated linearly or exponentially.

Linear acceleration/deceleration is generally used during rapid forwarding, and acceleration/deceleration time constants are set for each axis by parameters. Further, exponential acceleration/deceleration is used during cutting feed and dry run, and similarly, acceleration/deceleration time constants are set by parameters for each axis.

Conventionally, only when commands for linear acceleration/deceleration are issued from consecutive program blocks, two blocks are executed in an overlapping manner to reduce machining time.

[Problem to be solved by the invention]

However, when two successive program blocks have different acceleration/deceleration types, the next program block cannot be executed until the distribution of command pulses by the former program block is completed.

The present invention has been made in view of these points, and it is an object of the present invention to provide an acceleration/deceleration control method that can always execute machining programs in an overlapping manner, regardless of the type of acceleration/deceleration between blocks.

[Means to solve the problem]

In order to solve the above problems, the present invention uses an acceleration/deceleration control method in which a machining program is executed block by block and the commanded speed of the tool is accelerated or decelerated linearly or exponentially.
A program execution means for executing two consecutive blocks of the machining program in an overlapping manner; a speed detection means for detecting the commanded speed of the tool during acceleration/deceleration; and a speed detected by the speed detection means as a reference speed. An acceleration/deceleration control method is provided, comprising: command means for commanding the start of execution of the next block in comparison with the first block.

[Effect]

Even if the acceleration/deceleration types of two consecutive program blocks are different, when the speed decreases to a predetermined ratio with respect to the program speed during deceleration, distribution of speed pulses for the next block is started.

〔Example〕

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

FIG. 1 is a block diagram showing a numerical control device for executing acceleration/deceleration control of the present invention. CN of machining program 1
The C command is converted into a predetermined execution format and read into the program execution means 2 program block by program block. This program execution means 2 can execute two consecutive blocks of the machining program 1 in an overlapping manner. The program execution means 2 is further connected to interpolation means 3.

The interpolation means 3 distributes pulses to each axis based on speed command data output from the program execution means 2. Although the explanation here assumes that the interpolated command pulses are output for only one axis, normally speed commands for multiple axes are output as distributed pulses.

The interpolation means 3 is connected to two acceleration/deceleration means, namely, an exponential acceleration/deceleration means 4a and a linear acceleration/deceleration means 4b. The distribution pulse output from this interpolation means 3 is either one of the
Alternatively, it is supplied to both acceleration/deceleration means. Further, the outputs of the two acceleration/deceleration means 4a and 4b are outputted to a speed adding circuit 5.

The command speed detection means 6 detects the command speed PR output from the linear acceleration/deceleration means 4b. The command speed detection means 6 outputs a speed signal V1 calculated based on the detected command speed FR to the execution start command means 7. The execution start command means 7 compares the speed PR detected by the command speed detection means 6 with the reference speed Fx and commands the start of execution of the next block. A parameter storage means 8 for providing a reference speed Fx is connected here.

Further, the speed adding circuit 5 is connected to a servo control section 9, and the servo control section 9 commands a speed to a servo motor 10 for driving the tool.

FIG. 2 shows the speed PR after acceleration/deceleration when the interpolated command speed FRrnax is given to the linear acceleration/deceleration means 4b by the interpolation means 3. Both the acceleration time constant and the deceleration time constant are set equal to TR. In the case of automatic acceleration/deceleration, if a parameter is set as an acceleration/deceleration time constant of 1, there is no need to issue a command using a program.

FIG. 3 shows an example of an exponential acceleration/deceleration curve with respect to a speed command during cutting feed or dry run.

When a command speed Fc is given from the interpolation means 3 to the exponential acceleration/deceleration means 4a in FIG. 1, the curve FC rises with the parameter-set acceleration/deceleration time constant TC and falls with the same time constant TC. Both acceleration/deceleration means 4a and 4b can smoothly start and stop movable parts such as tools at the start and end of movement.

FIG. 4 is an example of a speed curve when two consecutive blocks of a machining program are executed in an overlapping manner.

The first speed FR is determined based on the linear acceleration/deceleration command of the preceding program block. The following block commands exponential acceleration/deceleration. Then, at time t1 within the deceleration time in the preceding linear acceleration/deceleration, execution of the exponential acceleration/deceleration block is started.

That is, the second speed FC is determined after time tl based on the exponential acceleration/deceleration command. During a transient period in which two program blocks are executed in an overlapping manner, the first speed FR and the second speed FC are added together and output. Therefore, by integrating the commands of each block of the machining program, it is possible to shorten the machining time without changing the originally designated moving distance.

Note that, prior to execution of the machining program, the first speed P
The rate of deceleration of R is set in the parameter storage means, and time t1 is determined from the reference speed Fx determined by the set value.

FIG. 5 is a control flowchart showing an example of acceleration/deceleration control of the present invention. In the figure, the number following S indicates the step number.

[S1] The interpolated speed output from the interpolation means 3 is subjected to linear acceleration/deceleration control, and a speed pulse is output.

[S2] When the speed command of the preceding block falls into a linear deceleration region, its speed FR is compared with the reference speed Fx.

When the speed is reduced to the reference speed Fx, that is, when Fx≧PR, the process proceeds to the next step 83.

[S3] Execute the exponential acceleration/deceleration command instructed in the next program block. That is, the second speed pulse is output from the exponential acceleration/deceleration means 4a, which has a register different from the register storing the linear acceleration/deceleration command.

[S4] Add the two speed pulses output in steps S1 and S3 above.

[S5] In step S1, the first speed pulse PR commanded by the preceding block has been output, so the speed pulse FR or (PR+FC) is output to the servo control section 9 as the speed command.

The above explanation is for the case where the speed command of the preceding block is linear acceleration/deceleration, and thereby the machining efficiency is increased when transitioning from rapid feed to cutting control. Conversely, the same can be applied to a program block that transitions from exponential acceleration/deceleration to linear acceleration/deceleration, and machining efficiency in that case can also be improved.

Further, the reference speed Fx may be determined according to the amount of movement after deceleration.

〔Effect of the invention〕

As explained above, if the present invention is applied to a numerical control device that has the function of overlapping and executing a machining program between two consecutive blocks, the acceleration/deceleration type will be different for each block of the machining program. However, since the program execution efficiency does not decrease, machining time can be shortened.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing a numerical control device for executing acceleration/deceleration control of the present invention, Figure 2 is a diagram showing a speed curve after acceleration/deceleration by the linear acceleration/deceleration means, and Figure 3 is an exponential acceleration/deceleration curve. FIG. 4 is a diagram showing an example of a speed curve when two consecutive blocks are executed in an overlapping manner. FIG. 5 is a control flowchart showing an example of acceleration/deceleration control of the present invention. . 2 Program execution means 3 Interpolation means 4a Exponential acceleration/deceleration means 4b Linear acceleration/deceleration means 5 Speed addition circuit 6 Command speed detection means 7 to execution start command means 8 Parameter storage means Patent applicant FANUC Corporation Fig. 5

Claims (3)

[Claims] (1) In an acceleration/deceleration control method in which a machining program is executed block by block and the command speed of the tool is accelerated or decelerated linearly or exponentially, two consecutive blocks of the machining program are executed in an overlapping manner. A speed detection means for detecting a commanded speed of the tool during the acceleration/deceleration, and a command means for comparing the speed detected by the speed detection means with a reference speed and commanding the start of execution of the next block. An acceleration/deceleration control method characterized by having the following. (2) In an acceleration/deceleration control method of a numerical control device that executes a machining program to determine a command speed of a tool, the first speed is determined based on a linear acceleration/deceleration command in a program block executed by the numerical control device. determining, detecting that the first speed has been decelerated to a predetermined rate, and commanding exponential acceleration/deceleration in a program block following the program block; An acceleration/deceleration control method characterized in that the second speed and the first speed are added together and output. (3) The acceleration/deceleration control method according to claim 2, wherein the deceleration rate of the first speed is set as a parameter prior to execution of the machining program.