JPH0695727A - Feed speed clamping system - Google Patents

Abstract

PURPOSE:To most suitably clamp the feed speed in accordance with the internal processing time with respect to the feed speed clamping system for a numerical controller. CONSTITUTION:A preprocessing means 2 reads out and analyzes a working program 1 to obtain a feed speed F and outputs a command speed Fc. A BPT measuring means 3 measures BPT as the time which is required for read and analysis of one block of the working program 1 by the preprocessing means 2. A speed clasping means 4 compares the feed speed F and a limit speed Flim obtained from BPT with each other and clamps lower one and outputs it as the command speed Fc. A pulse distributing means 5 distributes a pulse (p) to a servo motor 27 based on the command speed Fc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feed rate clamp system for a numerical controller, and more particularly to a feed rate clamp system for controlling a servo motor by clamping a feed rate commanded by a machining program according to a tool movement amount of a block. Regarding

[0002]

2. Description of the Related Art Conventionally, in a numerical controller, a work is machined into a desired shape by moving a tool on a machining path designated by a machining program based on a designated feed rate.

By the way, in order to prevent a shock to the machine tool, an excessive load to the servo motor, etc., in the pre-processing of each block of the machining program, the tool feed speed and its speed change in each block. Is obtained in advance, and the actual feed rate is clamped to an appropriate value based on the result.

As one of the methods for clamping the feed rate, there is pre-interpolation acceleration / deceleration for accelerating / decelerating the tangential speed for interpolation (pulse distribution). According to this method, since the acceleration or deceleration is smoothly performed in the previous block so that the command speed of the block is achieved at the time of execution, it is possible to prevent a shock or the like to the machine tool.

[0005]

However, in the case of precision machining in which minute blocks are continuous, such as a curved path, if speed clamping is performed by acceleration / deceleration before interpolation, pulse distribution may not be in time and pulses may be interrupted. is there. As an example of this, as shown in FIG.
After that, since the minute blocks are continuous, the deceleration is first performed during the machining, and then the acceleration / deceleration is performed according to the movement distance commanded by each block. Therefore, since the commanded speed Fc fluctuates, the machined surface becomes rough and desired machining accuracy cannot be obtained.

If the feed speed F is suppressed in advance, the feed speed F can be increased to the virtual speed Fx from time t81 to time t82 as shown in FIG. Since processing is performed only at F, processing time becomes long. Since it is necessary to investigate all the blocks of the machining program as to how much the feed rate F should be suppressed, a great deal of labor is required,
There is a problem that work efficiency is reduced.

Further, there is a problem that the optimum feed rate F cannot be set because the operator has no means for knowing the processing time in one block of the machining program executed in the numerical controller.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a feed rate clamp system for optimally clamping the feed rate in accordance with the internal processing time of the numerical controller.

[0009]

In order to solve the above-mentioned problems, the present invention solves the above-mentioned problems by reading and analyzing a machining program in a feeding speed clamp system in which a feeding speed commanded by a machining program is clamped to control a servo motor. BPT (Bl), which is the time required for the pre-processing means to go on to obtain the feed speed and output the command speed and the pre-processing means to read and analyze one block of the machining program.
BPT measuring means for measuring (ock Processing Time),
A speed clamp means for comparing the feed speed and the limit speed obtained from the BPT and clamping the smaller speed, and outputting the command speed, and a pulse output to a servo motor based on the command speed. And a pulse distributing means for distributing.

[0010]

First, the BPT measuring means measures the BPT, which is the time required for the preprocessing means to read and analyze one block of the machining program. Next, the preprocessing means reads out and analyzes the machining program to obtain the feed speed, and outputs the command speed obtained by the speed clamp means. Then, the pulse distributing means distributes the pulses to the servomotors based on the command speed output from the preprocessing means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of an interactive numerical control device which is one of the numerical control devices to which the present invention is applied.

The processor 11 controls the entire numerical controller according to the system program stored in the ROM 12. EPROM or EEPROM is used for the ROM 12. SRAM 13 is used as the RAM 13, and B
Various data such as PT (Block Processing Time), feed speed and command speed, or input / output signals are stored.
The non-volatile memory 14 uses a CMOS backed up by a battery (not shown), and stores parameters, pitch error correction amount, tool correction amount, and the like that should be retained even after the power is turned off.

The graphic control circuit 15 converts the digital signal into a signal for display and gives it to the display device 16. A CRT or a liquid crystal display device is used as the display device 16. The display device 16 displays a shape, processing conditions, etc. when creating a processing program in an interactive form. The keyboard 17 is composed of symbolic keys, numerical keys, etc., and is used to input necessary graphic data and NC data. The timer 26 ticks the date and time, outputs the time data in response to a command from the processor 11, and outputs an interrupt signal to the processor 11 at every predetermined time set by the processor 11.

The axis control circuit 18 receives the axis movement command from the processor 11 and outputs the axis command to the servo amplifier 19. The servo amplifier 19 receives the command of the axis and drives the servo motor 27 of each axis provided in the machine tool 20.

The above components are connected to each other by a bus 21. A PMC (Programmable Machine Controller) 22 receives a T function signal (tool selection command) and the like via the bus 21 when executing an NC program. Then, this signal is processed by the sequence program, a signal is output as an operation command, and the machine tool 20 is controlled. Further, it receives a status signal from the machine tool 20, performs a sequence process, and transfers a necessary input signal to the processor 11 via the bus 21.

Further, the bus 21 has software keys 23 and N whose functions change according to a system program or the like.
A serial interface 24 for sending C data to an external device such as a floppy disk, a printer, or a paper tape reader (PTR) is connected. The software key 23 is provided on the CRT / MDI panel 25 together with the display device 16 and the keyboard 17.

In addition to the processor 11 which is the CPU for NC, the bus 21 is connected with a processor 31 for interaction having a bus 30. ROM 32 on the bus 30,
The RAM 33 and the non-volatile memory 34 are connected.

An input screen for interactive data displayed on the display device 16 is stored in the ROM 32. On this interactive data input screen, the entire motion trajectory of the tool and the like are displayed as a background animation when the NC sentence is created. Further, the work or data that can be set by the input screen is displayed on the display device 16 in a menu format. The item to be selected from the menu is selected by the software key 23 arranged at the bottom of the screen corresponding to the menu. The meaning of the software key 23 changes for each screen. An SRAM or the like is used as the RAM 33, and various data for dialogue are stored.

The input data is the processor 3 for dialogue.
1 is processed to create a work machining program, and a background animation is sequentially displayed on the display device 16 used interactively. The work machining program stored as an NC sentence in the non-volatile memory 34 is also executed during the machining simulation of the machine tool 20, and is displayed in the foreground animation.

FIG. 1 is a diagram for explaining the principle of the present invention. The feed rate clamping method of the present invention comprises a preprocessing unit 2, a BPT measuring unit 3, a velocity clamping unit 4 and a pulse distributing unit 5. The preprocessing unit 2 and the BPT measuring unit 3
The speed clamp means 4 is a function realized by the processor 11 executing the system program stored in the ROM 12 of FIG. The pulse distributing means 5 corresponds to the axis control circuit 18 and the servo amplifier 19 shown in FIG.

The preprocessing means 2 reads out and analyzes the machining program 1 to obtain the feed speed F, and the command speed F
Output c. The BPT measuring means 3 measures the BPT, which is the time required for the preprocessing means 2 to read and analyze one block of the machining program 1. The speed clamp means 4 has a limit speed Fli obtained from the feed speed F and BPT.
It is compared with m and clamped to the smaller speed, and output as the command speed Fc. Pulse distribution means 5
Distributes the pulse p to the servomotor 27 based on the command speed Fc.

Next, the operation of the feed rate clamp system of the present invention will be described. First, the BPT measuring means 3 is executed only at a predetermined time such as when the system is started up or when the parameter relating to the feed rate is changed. Specifically, the operator sets a parameter for BPT measurement to, for example, "1". On the contrary, when the BPT measurement is not performed as in actual machining, the above parameter is set to, for example, "0". Here, the BP measured by the BPT measuring means 3
T is an internal processing time required for the preprocessing means 2 to read and analyze one block of the machining program 1.

The measured BPT is the distribution cycle ITP.
If it is shorter than this, the distribution cycle ITP is output to the preprocessing unit 2 as BPT. Here, the distribution cycle ITP is a constant numerical value set according to the servomotor 27 and the like, and indicates a cycle for distributing the pulse p.

After that, when the machining program 1 for actual machining or the like is read out to control the servomotor, the preprocessing means 2 is used.
Reads and analyzes the machining program 1 to obtain the feed rate F and the like. That is, predetermined processing including numerical calculation such as lexical analysis, syntactic analysis, coordinate calculation and correction amount calculation of the NC function instructed by the machining program 1 is performed, and the moving distance d, the feed speed F, and other necessary commands are specified. Ask.

BPT and feed rate F thus obtained
Is output to the speed clamp means 4. The speed clamp means 4 first measures the BPT [ms] measured by the BPT measuring means 3.
ec], the pulse weight CMR [mm / sec] set according to the servo motor 27, etc., and the movement distance d [mm] commanded in the block, at least one pulse per one distribution cycle according to the following equation. Limit speed Flim [mm / sec] that indicates output speed
Ask for.

Flim = (1 / BPT) × 1000 × 60 × CMR × d (1) Then, the obtained limit speed Flim and the feed speed F are compared with each other, whichever is smaller, that is, the slower one. It is clamped at the speed of and is output to the preprocessing means 2 as the command speed Fc.

The preprocessing means 2 outputs the command speed Fc output from the speed clamp means 4 to the pulse distribution means 5.
The pulse distribution means 5 distributes the pulse p to the servomotor 27 based on the command speed Fc.

Therefore, the servomotor 27 can be controlled by the optimum feed speed clamped according to the internal processing time of the interactive numerical control device, that is, the command speed Fc. For this reason, the processing time can be suppressed to the minimum, and the processing surface is smooth and desired processing accuracy can be obtained.

FIG. 3 is a flow chart showing the processing procedure of the BPT measuring means. In the figure, the number following S indicates a step number. [S31] The counter is initialized. That is, a predetermined address of the RAM 13 or the non-volatile memory 14 shown in FIG.
Initialize the registers of to zero. [S32] The timer interrupt is set. Specifically, a predetermined command is sent from the processor 11 to the timer 26, and an interrupt signal is generated at every interrupt time such as 1 [msec]. The timer 26 outputs an interrupt signal to the processor 11 at each set predetermined time. [S33] One block of the measurement program stored in advance in the ROM 12 of FIG. 2 or the input machining program is read. When the processor 11 receives the interrupt signal, step S38 is executed. [S34] The analysis process of the one block read in step S33 is performed. That is, predetermined processing including numerical calculation such as lexical analysis, syntactic analysis, coordinate calculation and correction amount calculation of the NC function commanded in the block is performed, and the moving distance d, the feed speed F and other necessary commands are specified. Ask. When the processor 11 receives the interrupt signal, step S3
Execute 8. [S35] The timer interrupt is released. Specifically, the processor 11 sends a predetermined command to the timer 26 to stop the generation of the interrupt signal. [S36] The feed speed F is calculated. Specifically, first, BPT [msec] is calculated from the numerical value of the counter. For example, 1
If it is an interrupt time of [msec], the value on the counter remains B
Although it becomes PT, if the interrupt time is 5 [msec], the value obtained by multiplying the value of the counter by 5 becomes BPT. [S37] The feed speed F and BPT are output. Specifically, the feed speeds F and BPT are set in a predetermined area such as a predetermined address of the RAM 13 or the non-volatile memory 14.
Then, this processing procedure is ended. [S38] The counter is incremented. That is, the value of the counter is incremented by 1. After this step ends, the procedure returns to the procedure before the interruption.

FIG. 4 is a flow chart showing the processing procedure of the speed clamp means. In the figure, the number following S indicates a step number. [S41] The limit speed Flim is calculated. Specifically, the above equation (1) is calculated from the BPT [msec], the pulse weight CMR [mm / sec], and the moving distance d [mm] measured in the processing procedure of FIG. [S42] The feed speed F is compared with the limit speed Flim calculated in step S41. If the feed speed F is larger than the limit speed Flim (YES), step S43.
And the feed speed F is smaller than the limit speed Flim (N
If it is O), the process proceeds to step S43. [S43] After outputting the limit speed Flim as the command speed Fc, this processing procedure ends. Specifically, the RAM 13
Alternatively, it is set in a predetermined area such as a predetermined address of the non-volatile memory 14, and this processing procedure is ended. [S44] After the feed speed F is output as the command speed Fc, this processing procedure ends. Specifically, the RAM 13 or the nonvolatile memory 14 is set in a predetermined area such as a predetermined address, and the present processing procedure is ended.

FIG. 5 is a flow chart showing the overall processing procedure of the feed rate clamp method of the present invention. In the figure, the number following S indicates a step number. [S51] Measurement parameters are set. In particular,
First, an operator calls a parameter setting screen by performing a predetermined operation. Then, in the parameter setting screen, set the bit of the parameter indicating the execution of the BPT measurement,
For example, it is set to "1". [S52] BPT measurement processing is performed. That is, the processing procedure shown in FIG. 3 is executed. [S53] The measurement parameter is canceled. Step S5
As in the case of 1, the parameter setting screen is called, and the bit of the parameter indicating the execution of the BPT measurement is set to, for example, “0”. [S54] One block of the machining program is read. [S55] The analysis process of the one block read in step S54 is performed. That is, predetermined processing including numerical calculation such as lexical analysis, syntactic analysis, coordinate calculation and correction amount calculation of the NC function commanded in the block is performed, and the moving distance d, the feed speed F and other necessary commands are specified. Ask. [S56] Speed clamp processing is performed. That is, the processing procedure shown in FIG. 4 is executed, and the obtained command speed Fc is output to the pulse distributing means 5 shown in FIG. [S57] It is determined whether or not another block exists in the machining program. If there are other blocks (YE
If S), the process returns to step S54, and if there is no other block (NO), this processing procedure ends.

FIG. 6 shows an example of the speed clamp when the processing procedure of the present invention shown in FIGS. 3 to 5 is carried out. As is apparent from FIG. 6, the velocity Fl1 is up to time t61.
Since the limit speed Flim is a small block continuous after the time t61, it is suppressed to the speed Fl2 from the time t61 to the time t62 and to the speed Fl3 after the time t62. By the limit speed Flim, the command speed Fc is similarly clamped to the speed Fl2 from the time t61 to the time t62 after the time t61 and to the speed Fl3 after the time t62.

Therefore, the servomotor 27 is controlled by the optimally clamped command speed Fc according to the internal processing time of the interactive numerical control device, so that the processing time is minimized and the processing surface is smooth and desired. The processing accuracy of can be obtained.

In the above description, the present invention is applied to the interactive numerical control device, but the present invention can also be applied to other numerical control devices that control the servomotor 27 based on the machining program 1.

The BPT measuring means 3 is configured to be executed by the operator by setting predetermined parameters. However, a monitoring means for constantly monitoring parameters related to system start-up and feed speed is provided. It may be configured to be automatically executed when there is a change or the like. By doing this, B is set at a predetermined time such as when the system is started up or when the parameters related to the feed rate are changed.
Since the PT measuring means 3 was not executed, the command speed F
It is possible to prevent unexpected situations such as c not being optimally clamped.

[0036]

As described above, according to the present invention, the BPT
Since the measuring means measures the BPT which is the time required to read and analyze one block of the machining program, the preprocessing means calculates the feed speed and outputs the command speed calculated by the speed clamp means. The servo motor can be controlled by the optimum feed rate clamped according to the internal processing time of the numerical controller.

For this reason, the processing time can be minimized, and the processing surface can be made smooth and desired processing accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a block diagram showing a configuration of an interactive numerical control device.

FIG. 3 is a flowchart showing a processing procedure of BPT measuring means.

FIG. 4 is a flowchart showing a processing procedure of a speed clamp means.

FIG. 5 is a flowchart showing the overall processing procedure of the feed rate clamp method of the present invention.

FIG. 6 is a diagram showing an example of a speed clamp when the present invention is implemented.

FIG. 7 is a diagram showing an example of a conventional speed clamp.

FIG. 8 is a diagram showing an example of a conventional speed clamp.

[Explanation of symbols]

 11, 31 processor 12, 32 ROM 13, 33 RAM 14, 34 non-volatile memory 15 graphic control circuit 16 display device 17 keyboard 18 axis control circuit 19 servo amplifier 23 software key 26 timer 27 servo motor

Claims (2)

[Claims] 1. A feed rate clamping method for clamping a feed rate commanded by a machining program to control a servo motor, in which a machining program is read and analyzed to obtain a feed rate, and a preprocessing means for outputting the commanded rate. And BPT (Block) which is the time required for the preprocessing means to read and analyze one block of the machining program.
Processing time), a BPT measuring unit, a speed clamping unit that compares the feed speed with a limit speed obtained from the BPT, clamps at the smaller speed, and outputs the clamped speed as the command speed, A feed speed clamp system, comprising: pulse distribution means for distributing pulses to be output to a servo motor based on speed. 2. The feed rate according to claim 1, wherein the BPT measuring means is configured to be executed only at a predetermined time such as when the system is started up or when a parameter relating to the feed rate is changed. Clamp method.