JPH06175717A - Tool path control system - Google Patents

Abstract

PURPOSE:To perform the corner machining without generating any machining error even if a tool moved along a corner circular arc. CONSTITUTION:A preprocessing arithmetic means 42 reads both blocks set right before and after a corner out of a corner part machining program 41 and outputs the corner part processing information to a tool path corrector means 44. The means 44 reads the radius R of the tool out of a memory 45 and also applies the offset to the tool path set based on the corner part machining information by an extent equal to the raius R. Thus, an offset tool path is obtained. At the same time, a shift correcting amount of the tool is calculated from a corner circular arc tool path obtained by connecting a point where the offset tool path corresponding to the block set right before the corner is extended toward the path by a prescribed distance to a point where the offset tool path corresponding to the block set right after the corner is extended in the opposite direction to the path by a prescribed distance. The tool moving along a corner circular arc is completely separated from a work. Therefore, a machining error is never generated at a corner even if a servo motor or a machine has a follow-up delay.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool path control system for correcting a tool path of a numerically controlled machine tool, and more particularly to a tool path control method for offsetting a tool radius correction amount to obtain a corner arc tool path.

[0002]

2. Description of the Related Art In a numerical control device (CNC), a path in which a radius of a tool is offset is automatically calculated in a path designated by a machining program, and the tool path is moved along the offset path. It is in control. In this tool path control, the offset tool path when moving outside the corner is determined as follows.

FIG. 4 is a diagram showing a first example of a conventional offset tool path. In the figure, consider a case where a workpiece 10A having a corner 30A at a right angle is machined from a material 100A. The paths commanded by the machining program are the path 1A by the block immediately before the corner and the path 2A determined by the block immediately after the corner. In this case, CNC
Is the path 12A and 2 with the tool radius offset.
2A is calculated automatically and the tool is moved along its offset path 12A and 22A. The offset tool paths 12A and 22A are paths at the center position of the tool.

However, in such offset tool paths 12A and 22A, before and after the tool passes through the corner 3A, the distance between the tool and the work 10A is equal to or larger than the radius of the tool, so the tool is separated from the work 10A, Some parts are not actually processed. Further, when passing through the corner 3A that bends at a right angle, the tool is decelerated in order to reduce the shock of the machine tool, and the machining speed is reduced accordingly.

Therefore, in order to solve such a problem, the tool is moved along an offset tool path having a corner arc as shown in FIG. Figure 5
FIG. 6 is a diagram showing a second example of a conventional offset tool path. In the figure, the difference from the first example is that a corner arc 3B is inserted between the offset tool paths 12B and 22B. The radius of the corner arc 3B corresponds to the radius of the tool. Therefore, unlike the first example, even if the tool passes through the corner 3B, the tool does not separate from the work 10A during that time. Further, since the distribution pulse for each axis is smoothed by inserting the corner arc, the shock received by the machine tool is not so large and it is not necessary to decelerate the tool.

[0006]

However, in the above second example, when the tool moves along the corner arc 3B, an inner rotation error occurs due to a tracking error on the servo motor or the machine side. As a result, the corner 30B of the work 10B
There is a problem that a machining error occurs in the corner and the corner angle cannot be accurately obtained.

The present invention has been made in view of the above circumstances, and provides a tool path control system capable of performing corner machining without causing a machining error even if the tool is moved along a corner arc. The purpose is to

[0008]

In order to solve the above problems, the present invention reads a block immediately before a corner and a block immediately after a corner of a corner machining program in a tool path control system for controlling a tool path of a numerically controlled machine tool. Pre-processing calculation means for outputting corner portion machining information, and an offset corresponding to the immediately preceding corner block when obtaining an offset tool path offset by a correction amount of the tool diameter with respect to the tool path based on the corner portion machining information A corner arc obtained by connecting an extension point obtained by extending the tool path by a predetermined distance in the path direction and an extension point obtained by extending the offset tool path corresponding to the block immediately after the corner by a predetermined distance in the direction opposite to the path direction. Output from the tool path correcting means and the tool path correcting means for obtaining the movement correction amount of the tool from the tool path A tool path control system is provided, which comprises: an addition unit that adds a dynamic correction amount to a movement command from the preprocessing calculation unit to obtain a movement amount; and an interpolation unit that interpolates the movement amount. .

[0009]

The preprocessing operation means reads the block immediately before the corner and the block immediately after the corner of the corner machining program, and outputs the corner machining information. The tool path correcting means obtains an offset tool path by offsetting the tool path based on the corner machining information by the correction amount of the tool diameter. At that time, the extension point where the offset tool path corresponding to the block immediately before the corner is extended by a predetermined distance in the path direction, and the offset tool path corresponding to the block immediately after the corner is extended by a predetermined distance in the direction opposite to the path direction. The movement compensation amount of the tool is obtained from the corner arc tool path obtained by connecting the extension points. The addition means adds the movement correction amount output from the tool path correction means to the movement command from the preprocessing calculation means to obtain the movement amount, and the interpolation means interpolates the movement amount.

When the tool is moved along the corner arc thus determined, the tool moves completely away from the work at the corner, so that no machining error occurs at the corner.

[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 an explanatory diagram of the tool path control system of the present invention. In the figure, consider a case where a workpiece 10 having a right angle corner 30 is machined from a material 100. The machining shape instructed by the machining program is a shape composed of the path 1 determined by the block immediately before the corner and the path 2 determined by the block immediately after the corner. The CNC offsets the paths 1 and 2 by the radius R of the tool, and automatically calculates the offset tool path 200 along which the tool actually moves. The offset tool path 200
Is the passage in the center of the tool.

The offset tool path 200 is formed by the straight paths 12, 13, 23, 22 and the corner arc path 3. The straight path 12 is a path obtained by directly offsetting the path 1 determined by the block immediately before the corner, and the straight path 22 is a path obtained by directly offsetting the path 2 determined by the block immediately after the corner.

The straight path 13 is obtained as follows. That is, first, a straight line 11 that extends from the end point C of the path 1 determined by the immediately preceding block to the outside of the corner 30 perpendicularly to the path 1 is created. An intersection P1 between the straight line 11 and the straight line path 12 is obtained, and further, the intersection P
A point P2 extending from 1 in the tool path direction by a constant distance D is obtained. The straight path 13 is a path connecting the point P1 and the point P2.

Further, the straight line path 23 is obtained as follows, similarly to the straight line path 13. That is, first, a straight line 21 that extends from the starting point C of the path 2 determined by the block immediately after the corner to the outside of the corner 30 perpendicularly to the path 2 is created.
An intersection point P3 between the straight line 21 and the straight line path 22 is obtained, and further, a point P4 extending from the intersection point P3 by a constant distance D in a direction opposite to the tool path direction is obtained. The straight path 23 is a path connecting the points P3 and P4.

The corner arc 3 is formed by connecting the point P3 and the point P4. The tool moves along the offset tool path 200 thus determined, and moves along the corner arc 3 at the corner. As described above, the corner arc 3 is formed by connecting the points P2 and P4 that are apart from the point P1 and the point P3 by the constant distance D. Therefore, the tool that moves along the corner arc 3 moves completely away from the work 10. Therefore, even if there is a tracking delay on the servo motor or machine side, a machining error at the corner 30 does not occur.

FIG. 3 is a flow chart showing the processing procedure of the present invention. In the figure, the numerical value following S indicates a step number. [S1] It is determined whether or not the tool radius correction process is performed on the outside of the corner. If it is outside the corner, step S2
Otherwise, go to step S7. [S2] Path 1 determined by the block immediately before the corner
A straight line 11 is formed perpendicular to the path 1 from the end point C to the outside of the corner 30. [S3] An intersection P1 between the straight line 11 and the straight path 12 obtained by offsetting the path 1 by the tool radius correction amount is obtained, and a point P2 extending from the intersection P1 by a constant distance D in the tool path direction is obtained. [S4] Path 2 determined by the block immediately after the corner
A straight line 21 is formed perpendicular to the path 2 from the starting point C of the above and goes to the outside of the corner 30. [S5] An intersection P3 between the straight line 21 and a straight path 22 obtained by offsetting the path 2 by the tool radius correction amount is obtained, and a point P4 extended from the intersection P3 by a constant distance D in the direction opposite to the tool path direction. Ask for. [S6] A corner arc connecting the points P2 and P4 is formed. [S7] Since it is not the tool radius correction process for the outside of the corner, the conventional tool radius correction process is performed.

FIG. 1 is a block diagram of a tool path control system of the present invention. In the figure, the pre-processing calculation means 42 reads the block immediately before the corner and the block immediately after the corner of the corner machining program 41, and outputs the corner machining information to the tool path correcting means 44. In the tool path correcting means 44, the radius R of the tool stored in the memory 45 is read, and R is applied to the tool paths 1 and 2 based on the corner machining information.
Offset by 12 minutes, offset tool path 12, 22
Ask for. At that time, an extension point P2 obtained by extending the offset tool path 12 corresponding to the block immediately before the corner by a predetermined distance D in the path direction, and the offset tool path 22 corresponding to the block immediately after the corner by a predetermined distance in the direction opposite to the path direction. The tool movement correction amount is obtained from the corner arc tool path 3 obtained by connecting the extension point P4 extended by D. The addition means 46 adds the movement correction amount output from the tool path correction means 44 to the movement command from the preprocessing calculation means 42 to obtain the movement amount, and the interpolation means 48 interpolates the movement amount to obtain an interpolation pulse. Is output.

The interpolation pulse is accelerated / decelerated by the acceleration / deceleration control means 49 and sent to the position control circuit 50. The position control circuit 50 converts the interpolation pulse into a speed command signal and sends it to the servo amplifier 51. The servo amplifier 51 amplifies this speed command signal and drives the servo motor 52. The servo motor 52 has a built-in pulse coder and feeds back the position feedback pulse to the position control circuit 50.

In FIG. 1, the acceleration / deceleration control means 49, the position control circuit 50, the servo amplifier 51, and the servomotor 52 are shown for only one axis, and the elements of the other axes have the same structure and are therefore omitted. . Further, in FIG. 1, the spindle amplifier, the spindle motor, etc. are omitted.

[0020]

As described above, in the present invention, when the tool passes through the outside of the corner in the machining of the corner portion, the offset tool path is extended by a certain distance and then the corner arc is formed.

Therefore, the tool that moves along the corner arc moves completely away from the work. Therefore, even if there is a tracking delay on the servo motor or machine side, a machining error at the corner does not occur.

[Brief description of drawings]

FIG. 1 is a block diagram of a tool path control system of the present invention.

FIG. 2 is an explanatory diagram of a tool path control system of the present invention.

FIG. 3 is a flowchart showing a processing procedure of the present invention.

FIG. 4 is a diagram showing a first example of a conventional offset tool path.

FIG. 5 is a diagram showing a second example of a conventional offset tool path.

[Explanation of symbols]

 1 Path determined by block immediately before corner 2 Path determined by block immediately after corner 3 Corner arc 10 Work piece 12, 13, 22, 23 Straight path 42 Pre-processing calculation means 44 Tool path correction means 45 Memory 46 Addition means 48 Interpolation means 200 Offset tool path D Constant distance R Tool radius

Claims (1)

[Claims] 1. In a tool path control system for controlling a tool path of a numerically controlled machine tool, a preprocessing operation means for reading a block immediately before a corner and a block immediately after the corner of a corner part machining program and outputting corner part machining information, said corner. When obtaining an offset tool path offset by a correction amount of the tool diameter with respect to the path based on the part machining information, an extension point obtained by extending the offset tool path corresponding to the block immediately before the corner by a predetermined distance in the path direction,
A tool path correcting means for obtaining a movement correction amount of the tool from a corner arc tool path obtained by connecting an offset tool path corresponding to the block immediately after the corner with an extension point obtained by extending a predetermined distance in a direction opposite to the path direction; And an addition unit that adds the movement correction amount output from the tool path correction unit to the movement command from the preprocessing calculation unit to obtain the movement amount, and an interpolation unit that interpolates the movement amount. Tool path control method to be used.