JP2925414B2 - Speed control method and apparatus for numerically controlled machine tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control method and apparatus for a numerically controlled machine tool, and more particularly to a speed control method and apparatus for a numerically controlled machine tool for improving machining efficiency.

[0002]

2. Description of the Related Art In numerically controlled machine tools, there has been a remarkable improvement in machining efficiency, and rapid feed rates and cutting feed rates have been increasing. By the way, when performing the machining in which the rapid traverse and the cutting feed are successively performed, as shown in FIG.
Stop and stop confirmation are performed, and then cutting feed acceleration is performed. This is the same at the time of transition from cutting feed to rapid feed.

[0003]

As described above, in the conventional numerically controlled machine tool, it is necessary to always perform deceleration stop, stop confirmation, and acceleration when performing machining in which rapid traverse and cutting traverse are performed successively. However, in a machining command that is continuous in the same direction from the rapid traverse to the cutting feed, such deceleration stop, acceleration, and the like become a hindrance to speeding up the rapid traverse and the cutting feed. For example, in a fixed cycle such as a deep hole machining cycle, rapid feed and cutting feed in the Z direction are frequently and alternately commanded, and rapid feed and cutting feed in the same direction are repeated many times.

[0004] Therefore, an object of the present invention is to provide rapid feed and cutting feed continuously in any order, and if they are feeds in the same direction, stop the axial feed at the transition between rapid feed and cutting feed. It is an object of the present invention to provide a speed control method and apparatus for a numerically controlled machine tool that eliminates dead time as much as possible and improves machining efficiency.

[0005]

To solve the above-mentioned problems, a speed control method for a numerically controlled machine tool according to the present invention comprises:
In a numerical control machine tool speed control method for driving a feed axis in accordance with an NC program command and processing a workpiece into a desired shape, the NC program command is continuously issued in rapid feed and cutting feed in any order, And it is determined whether or not they are feeds in the same direction, and fast feed and cutting feed are sequentially commanded, and when it is determined that they are feeds in the same direction, the feed shaft is shifted at the transition between rapid feed and cutting feed. , The feed speeds of the rapid feed and the cutting feed are continuously connected without stopping. Further, the speed control device for a numerically controlled machine tool according to the present invention is a speed control device for a numerically controlled machine tool that drives a feed shaft in accordance with a command of an NC program to machine a workpiece into a desired shape.
A first means for reading the C program and determining the type of the fast feed and the cutting feed and the feed direction thereof, and the first means instructing the rapid feed and the cutting feed continuously in any order, and When it is determined that the feed
Second means for continuously connecting the feed speeds of the rapid feed and the cutting feed without stopping the feed shaft at the transition between the rapid feed and the cutting feed.

[0006]

According to the present invention, when rapid traverse and cutting feed are successively commanded, when it is not necessary to stop such as at the transition from rapid traverse to cutting feed or at the transition from cutting feed to rapid traverse. The processing efficiency is improved by smoothly and temporally setting and connecting the speed change between the current processing and the next processing.

[0007]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing a processing procedure of a speed control method and apparatus of a numerically controlled machine tool according to the present invention. First, as a result of decoding the NC command program, the current block is fast-forward and the next block is cutting feed.
It is determined whether these feed directions are the same (step S1). If YES is determined in step S1, the speed at the fast-feed end point position is set as the next block command cutting speed, and a predetermined deceleration is performed (step S2). Next, the speed distribution at the cutting feed start point position is started at the commanded speed (step S3).

If NO is determined in the step S1, it is determined whether or not the next block is rapidly traversed in the current block cutting feed and is in the same direction (step S4). Here, if YES, the speed at the cutting feed end point position is set as the command speed (step S5), the speed distribution at the rapid feed start point position is set as the cutting feed end position speed, and a predetermined rapid feed acceleration is performed (step S6). On the other hand, in step S4, NO
Is determined, deceleration, stop, and acceleration are performed as before (step S7).

FIG. 2 shows an example of the speed control of the above embodiment. In FIG. 2, fast-forward in N1 block, N2
Cutting feed is performed by the block, cutting feed is performed by the N3 block, and rapid feed control is performed by the N4 block. FIG. 3 shows FIG.
5 shows an example of the NC program of each block.

In FIG. 3, a movement from the current position is incrementally designated by G91, a rapid traverse (G00) and a rapid traverse target position (-100.000) are designated by a block N1, and a cutting feed (G01) is designated by a block N2. , The cutting feed speed (F4000) is specified, the block N3 specifies the cutting feed target position in the reverse direction, and the N4 fast-feeds (G
00) and the fast-forward target position (100.000).

The feed speed (absolute value) is controlled as shown in FIG. 2 according to the command program shown in FIG. That is, at the time of the transition from the rapid traverse to the cutting feed, the rapid traverse deceleration of the block N1 is started according to a predetermined deceleration curve so that the cutting feed speed F4000 is obtained at a time T2 when the cutting feed start position (rapid traverse target position: -100.000) is reached. The point T1 is determined, and the rapid traverse deceleration is started from the time T1. In the transition from the block feed to the rapid feed in the block N3 from the block N3, the feed speed at the end position of the cut feed is kept at F4000, and the acceleration of the fast feed is commanded from there. As is apparent from a comparison between FIG. 2 and FIG. 5, according to the present embodiment, the two feed speeds are continuously connected without stopping at the transition between the rapid feed and the cutting feed, so that the machining efficiency is improved. Is done.

When a command is issued continuously from the rapid traverse in the same direction as the cutting feed, the speed at the command ending position of the command of the rapid traverse is defined as the cutting feed speed commanded in the next block.
The speed is reduced according to a preset fast-forward acceleration / deceleration curve. The distribution of the cutting feed speed at the start point position of the next block is performed at the commanded cutting speed.

When a command is continuously issued in the same direction as the rapid feed from the cutting feed, the speed at the command feed end point is set as the commanded cutting feed speed, and the starting speed of the rapid feed of the next block is set as the cutting feed speed. From the speed, acceleration is performed according to a preset fast-forward acceleration / deceleration curve, and a predetermined fast-forward speed is set.

FIG. 4 is a block diagram showing an example of a speed control device for a numerically controlled machine tool according to the present invention for executing the above processing. The NC command program is decoded by the program decoding unit 1, and acceleration / deceleration control data is output from the acceleration / deceleration control unit 2 based on the decoding result. The information decoded by the program decoding unit 1 is sent to the fast-forward and cutting-feed combination control unit 6 and supplies a signal necessary for controlling the acceleration / deceleration control unit 2 to the acceleration / deceleration control unit 2.

The fast-forward / cut-feed joint controller 6 determines whether or not it is necessary to stop at the time of transition from the current block to the next block as described above. Processing, for example, deceleration control is started so as to reach a predetermined speed at the start of the next block. That is,
When the process shifts from rapid traverse to cutting feed or from cutting traverse to fast traverse, and when the speed changes in the same direction, the stop process is not necessary, so the process is performed as described above to improve the machining efficiency. The signal from the acceleration / deceleration control unit 2 is subjected to an interpolation process in the interpolation unit 3 and then sent to the motor 5 through the operation of the servo unit 4.

[0016]

As described above, the speed control method and apparatus of the numerically controlled machine tool according to the present invention can be used when the rapid traverse and the cutting feed are commanded continuously, when the transition from the rapid traverse to the cutting feed or the cutting is performed. If there is no need to stop, such as when shifting from feed to rapid traverse, the speed change between the current process and the next process can be smoothly set and connected in a timely manner to eliminate dead time, The efficiency is improved, especially when performing a deep hole processing cycle or the like.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure of a speed control method and apparatus of a numerically controlled machine tool according to the present invention.

FIG. 2 is a diagram showing a change over time in a feed speed for explaining the operation of the embodiment of FIG. 1;

FIG. 3 is a diagram illustrating an example of a command program for executing the processing of the embodiment illustrated in FIG. 2;

FIG. 4 is a diagram showing a configuration example of a speed control device of a numerically controlled machine tool according to the present invention.

FIG. 5 is a diagram showing a temporal change of a conventional feed speed.

[Explanation of symbols]

 1 Program decoding unit 2 Acceleration / deceleration control unit 3 Interpolation unit 4 Servo unit 5 Motor 6 Rapid feed / cut feed joint control unit

Claims (4)

(57) [Claims] 1. A speed control method for a numerically controlled machine tool for machining a workpiece into a desired shape by driving a feed axis in accordance with a command of an NC program, wherein the NC program command is such that rapid feed and cutting feed are continuously performed in any order. Command, and determine whether they are feeds in the same direction.When fast feed and cutting feed are sequentially commanded, and determine that they are feeds in the same direction, A speed control method for a numerically controlled machine tool, wherein the feed rates of the rapid feed and the cutting feed are continuously connected without stopping the feed axis at the time of transition. 2. When shifting from rapid traverse to cutting feed, the rapid traverse speed is reduced according to a predetermined deceleration curve so that the feed speed at the command end position of the rapid traverse command becomes the commanded cutting feed speed. 2. The speed control method for a numerically controlled machine tool according to claim 1, wherein the feed speed at the feed start position is set as the commanded cutting feed speed. 3. When shifting from cutting feed to rapid feed, a feed speed at a command end point of the cutting feed is set as a commanded cutting feed speed, and the feed speed of the rapid feed is set according to a predetermined acceleration curve from the cutting feed. 2. The speed control method for a numerically controlled machine tool according to claim 1, wherein the speed is accelerated. 4. A speed control device for a numerically controlled machine tool for driving a feed axis in accordance with a command of an NC program to machine a workpiece into a desired shape. The NC program reads the NC program and determines the type of fast feed and cutting feed and the feed direction. First means for determining, and fast forward and cutting feed are continuously commanded regardless of the order by the first means, and when it is determined that they are feeds in the same direction, the speed between the rapid feed and cutting feed is determined. A second means for continuously connecting the feed rates of the rapid feed and the cutting feed without stopping the feed axis at the time of shifting, a speed control device for a numerically controlled machine tool, comprising: