JPH01200408A - Tool correction system - Google Patents

Abstract

PURPOSE:To simply obtain a correction vector and to reduce the load of a processor by producing a basic correction vector on the line going to a point on a program path from the correction center of a tool correction system of a numerical controller CNC and obtaining the tool center from the program path and the correction vector. CONSTITUTION:A tool correction system is used to offset the tool center to the program path PP of a numerical control correction device. A correction center Pc is set in said correction system. Then, the basic correction vectors V1-V4 are produced on the line going to a point on the path PP from the center Pc. A correction vector is obtained by multiplying the vectors V1-V4 by the correction value. Then, a tool center path TPC is obtained from the path PP and the vectors V1-V4. At the same time, plural correction centers Pc1-Pc3 are set if desired and the basic correction vectors V1-V8 are used to the program paths P1-P8 respectively. Then, the path TPC is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tool compensation method for offsetting the center of a tool with respect to a program path of a numerical control device (CNC).
In particular, it relates to a tool correction method that easily obtains a correction vector from a correction center and a point on a program.

[Conventional technology]

When using a circular tool such as a cutter with a numerical control device (CNC), the shape of the actual workpiece is created as a cutting program, and the center of the tool is offset by a radius from the program path. As a result, even if the tool radius changes, only the tool radius can be specified without changing the cutting program (This is a convenient and well-known tool correction method for general numerical control equipment (CNC)).

However, although the correction value can be easily set using the radius of the tool, there are the following two methods for determining the direction of the correction hector.

The first is a method in which the correction vector is specified by the program, and the programmer includes it in the addition program in consideration of the program path.

The second method is a method in which a numerical control device (CNC) automatically calculates a correction vector from the path of the Canadian program.

[Problem to be solved by the invention]

However, in the first method, when the shape of the workpiece becomes complicated, the amount of calculation becomes enormous, and the burden on the programmer becomes heavy.

In the second method, the calculation is automatically performed inside the numerical control unit (CNC), so there is no burden on the programmer. However, in order to calculate the correction vector, the program path must be It is necessary to calculate a correction vector corresponding to
The load on the internal processor is heavy, and the computation of the correction vector takes too much time, which may result in discontinuation of pulse distribution.

On the other hand, if the shape of the workpiece is a circle, a curve approximating a circle, or a similar curve approximated by a straight line, the direction of the correction vector may lie on a line connecting a specific point and a point on the program path. Common.

The present invention has been made in view of these points, and it is an object of the present invention to provide a tool correction method that easily obtains a correction vector from a correction center and a point on a program.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a numerical control device (
In a tool correction method that offsets the tool center with respect to the program path of CNC, a correction center is set, a basic correction vector is created on a line from the correction center to a point on the program path, and the basic correction vector is A tool correction method is provided, characterized in that a correction vector is obtained by multiplying by a correction amount, and a tool center path is obtained from the program path and the correction vector.

[Effect]

Since the correction vector number σ can be easily calculated from the given correction center and the point of the program path, it is only necessary to specify the correction center in the program, which reduces the burden on the processor inside the numerical control unit (CNC) and reduces the burden on the correction vector. Pulse distribution is not interrupted due to calculations.

〔Example〕

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

11N shows a principle diagram of the tool correction method of the present invention.

In the figure, Pc is the correction center and PP is the program path, which usually corresponds to the shape of the workpiece.

The program path PP passes through points P1, P2, P3, P4. ■1, ■2, ■3, and ■4 are correction vectors, which are on the line connecting the correction center Pc and the point Pl on the program path. For example, the correction vector 1 is on a line connecting the correction center Pc and Pl on the program path PP. Therefore, the corrected tool center path TPc is determined by each correction vector ■1 to
■This is the point that connects the points TPI, TP2, TP3, and TP4 at the tip of 4.

Such correction vectors ■1 to v4 are located on the line connecting the two points once the correction center Pc and the points P1 to P4 of the program paths P and P are determined, and can be easily obtained using a numerical control device (CNC). The load on the internal processor becomes lighter.

FIG. 2 shows an example in which there are a plurality of correction centers. Second
In the figure, there are three correction centers, and the correction centers are changed as the program path PP progresses. For example, the correction center Pcl is used for points P1 to P3 on the program path PP, the correction center Pc2 is used for points 24 to P6, and the correction center Pc3 is used for points P7 to P8. Therefore,
This is effective when a curve made up of circular arcs having different center points is approximated by a straight line. Since the other symbols are the same as in FIG. 1, their explanation will be omitted.

FIG. 3 shows an example where the program path is a curve. In the figure, the correction center is only one point Pc, the program path PP is a curve, correction vectors V1 to 4 are created on points P1 to P4, and the tool center path TPc is determined. Other symbols are the same as in FIG.

Even if the program path is a curve and there are multiple correction centers, the tool center path can be found in the same way.

Furthermore, the method can be similarly applied to a mixture of straight lines and curved lines, or to special curves such as helicals and ellipses.

Next, software processing for implementing the present invention will be described. FIG. 4 shows a flowchart of the software of the present invention. In the figure, the numerical value following S is the step number.

(So) Read the machine program and determine the tool correction mode. If Do is commanded, go to Sl, G41P
If cn has been commanded, the process goes to S3; if G40 has been commanded, the process goes to S8.

(Sl) Do means correction cancellation, and the tool correction mode is set to cancel mode.

[S2] Return the tool center path to the program path.

(S3) G41Pcn has tool compensation mode, Pcn
specifies the correction center. Therefore, the tool correction mode is set to correction mode, and the correction center is set to the designated point Pcn.

[S4] A basic vector vb, which is the successor of the correction vector, is created from the correction center Pcn and the point of the program path.

[S5] Multiply the basic vector vb by the correction scale to find the correction vector Vn.

[S6] Add the correction vector Vn to the command value (point on the program path) to find the corrected position (tool center path).

[S7] The new correction vector Vn is the old correction vector ■
Save as 0.

FIG. 5 shows a diagram for explaining the processing in the tool correction mode. In the figure, Pcn is the center of correction, and point P
7-1 is a position in the previous block, point Pn is a commanded position on the program, vector vb is a basic vector, and Vn is a correction vector. From these, the corrected position (point on the tool center path) TPn is determined.

Next, return to the flowchart diagram in FIG.

(S8) G40 is a correction vector holding command, and sets the tool correction mode to correction vector holding mode.

[S9] Even if the program path moves to a new point, the correction vector is maintained as it is.

FIG. 6 shows an example of the tool center path in this case.

In the figure, each reference symbol is the same as in Figure 5, and here,
Even if the commanded position of the previous block moves from Pn-1 to commanded position Pn, the correction vector 0 is maintained as it is, and the corrected position TPn is determined.

In this way, the correction vector is obtained from the predetermined correction center and each point (command value) of the program path, and the tool center path (
(position after correction).

FIG. 7 shows a numerical control device (CNC) for implementing the present invention.
) hardware configuration is shown. In the figure, 11 is a processor that controls the whole, 12 is a ROM in which a control program is stored, 13 is a RAM in which various data are stored, and 14 is a nonvolatile memory in which programs, parameters, etc. are stored. , bubble memory, etc. are used. 14a is a Canadian program.

15 is a PMC (programmable machine controller) which receives commands such as Mi function and T function, converts them into signals for controlling the machine tool, and outputs the signals. The T code for tool selection is also sent to the PMC (Programmable Machine Controller) 15, processed by the sequence program 15a of the PMC 15, and then output from the input/output circuit to the control circuit on the machine side. A display control circuit 16 converts a digital signal into a display signal. 16a is a display device, such as a CRT or a liquid crystal display device. Reference numeral 17 denotes a keyboard, which is used to input tool correction amounts and the like.

18 is a position control circuit for controlling the servo motor, 1
9 is a servo amplifier for controlling the speed of the servo motor, 20 is a servo motor, 21 is a tacho generator for speed feedback, 22 is a position detector, a pulse coder,
An optical scale or the like is used. These elements are required for each axis, but only one axis is described here.

Reference numeral 23 denotes an input/output circuit for exchanging digital signals with the outside, and a tool selection signal (T signal) for controlling tool exchange is also output from here to the machine-side control circuit. 24 is a manual pulse generator that digitally moves each axis.

[Effects of the Invention] As explained above, in the present invention, the correction vector is obtained from the given correction center and the point of the program path to obtain the tool center path, so the correction vector can be easily calculated. The load on the processor inside the numerical control unit (CNC) is reduced, and pulse distribution is not interrupted due to calculation of the correction vector.

In addition, since a plurality of correction centers are provided and specified by the program, the same effect can be obtained even when a curve is composed of curves such as circles having different centers, or when this curve is approximated by a straight line.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the tool correction method of the present invention, FIG. 2 is a diagram showing an example in which there are multiple correction centers, FIG. 3 is a diagram showing an example in which the program path is a curved line, and FIG. Figure 5 is a flowchart of the software of the present invention, Figure 5 is a diagram for explaining processing in tool correction mode, Figure 6M is a diagram showing an example of the tool center path in correction vector holding mode, Figure 7 is the invention of the present invention. Numerical control equipment (CNC) to carry out
) is a diagram showing the hardware configuration of. 11--・-----Processor 12----------ROM2S---
−−−−−−1−・・−RAM14−・−・−・−−−
-----Nonvolatile memory 14 a---------・-
・-Machining program 15----------P
MC (Programmable Machine Controller) 15 a-----------Sequence program 16 a-----Display device 17----
−−・−−−−−・・−Keyboard Pc,, Pcl
NPc3, Pcn---1111----Correction center P P----1・-----Program path T P C----------・-- Tool center passage■1~V
B－－－－－－－－－－－One Correction Vector Patent Applicant Fanuc Co., Ltd. Agent Patent Attorney Takeshi Hattori Figure 3 Figure 4

Claims (6)

[Claims] (1) In a tool correction method that offsets the tool center with respect to the program path of a numerical control device (CNC), a correction center is set and a basic correction vector is created on a line from the correction center to a point on the program path. A tool correction method characterized in that: a correction vector is obtained by multiplying the basic correction vector by a correction amount; and a tool center path is obtained from the program path and the correction vector. (2) The tool correction method according to claim 1, wherein there are a plurality of correction centers. (3) The tool correction method according to claim 1, wherein the program path is formed of a straight line. (4) The tool correction method according to claim 1, wherein the program path is a curve. (5) The tool correction method according to claim 1, wherein the program path is composed of straight lines and curved lines. (6) The tool correction method according to claim 1, wherein the command program includes a cancel mode, a correction mode, and a correction vector holding mode.