JPH08257874A - Correcting method for nc machining program - Google Patents

Abstract

PURPOSE: To decrease an air cut as small as possible so as to improve machining efficiency, by performing measuring the external dimension of a workpiece, and correcting a program so that this measured dimension makes a machining start point, described in the program, approach a side of the workpiece. CONSTITUTION: An actual workpiece A is left as held by a holding device 4, and in lieu of a machining tool, a distance measuring device 11 is mounted on a spindle 6 on the side of a machining device 8, to measure a distance to the workpiece A, that is, an actual external diametric dimension related to machining. This external diametric dimension is compared with actual external diametric dimension built in a machining program. As a result, in the case of providing a dimensional difference, a machining start position is corrected so as to be adjacent to a side of the workpiece A in accordance with this dimensional difference. This corrected machining program is used. That is, an air cut is decreased as small as possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying an NC machining program.

[0002]

2. Description of the Related Art In recent years, many NC machine tools have been used for machining. This NC machine tool is controlled by a program and the machining dimensions of a workpiece are written in the program in advance.

By the way, when a workpiece is a cast product or a forged product, since the outer dimensions of the workpiece vary, a machining program is conventionally created by assuming a predicted maximum dimension. Was there.

[0004]

In the conventional machining program described above, air cutting (a state in which cutting is performed, but in reality, the workpiece is not yet in contact) is minimized by a cutting simulation or the like. However, if the outer dimension of the work piece is smaller than the expected dimension, air cutting cannot be avoided, and thus the machining efficiency is inevitably lowered.

Therefore, the present invention can solve the above-mentioned problems.
An object of the present invention is to provide a method for modifying a C machining program.

[0006]

In order to solve the above problems, a method for modifying an NC machining program according to the present invention measures the external dimensions of a workpiece with respect to an NC machining program that has already been created. If the measured dimension is smaller than the machining dimension described in the program, the program is modified so that the machining start point is brought closer to the workpiece side by a distance according to the dimension difference.

[0007]

According to the above construction, when the actually measured dimension is smaller than the assumed dimension of the workpiece, the machining program is set so that the machining start point is brought closer to the workpiece side by the distance according to the dimension difference. Since it is corrected, the air cut can be reduced as much as possible.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the program correcting method of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 is an NC machine tool, and a holding device 4 for holding a workpiece A via a mounting jig 3 is arranged at one end side of the support base 2 and the support base 2 is attached. On the other end side, a spindle 6 having a processing tool 5 attached to its tip, a motor for rotating the spindle 6, and an ATC
A processing device 8 including 7 and the like is arranged.

In the processing device 8, the processing tool 5, that is, the spindle 6 is movable in the up-down direction (X-axis direction), the left-right direction (Y-axis direction) and the front-rear direction (Z-axis direction).

Then, the numerical control section of the NC machine tool 1 processes the workpiece A into a predetermined shape (for example, drilling).
In order to do so, a machining program for moving (controlling) the machining tool 5 in the three-axis directions (X-axis, Y-axis, Z-axis direction) is stored.

In this machining program, the machining start position (for example, the R point position) is determined on the basis of the expected external dimensions of the workpiece A so as to minimize the air cut.

By the way, in the above-mentioned machining program, the machining start position is determined based on the assumed size of the workpiece A. Therefore, for example, when the workpiece A is a cast product or a forged product, It is often smaller than the assumed size, which inevitably increases the air cut.

Therefore, the machining program is modified. The method of modifying the machining program will be described below. That is, as shown in FIG. 2, the actual workpiece A is held by the holding device 4, and instead of the processing tool, the distance measuring device 11 is attached to the spindle 6 on the processing device 8 side, and the workpiece A is processed. Measure the distance to, ie the actual external dimensions related to the machining.

Then, the external dimensions are compared with the assumed dimensions incorporated in the machining program, and if there is a dimensional difference, the machining start position approaches the object A side according to the dimensional difference. Modified, and this modified machining program is used. That is, the air cut is reduced as much as possible.

If an unnecessary portion is generated when the above dimensional difference is eliminated, it is deleted from the machining program. Here, a more specific correction procedure will be described based on the flowchart of FIG.

First, the processing tool 5 is removed from the spindle 6, and a distance measuring device (for example, an ultrasonic range finder, a laser range finder, etc.) 11 is attached. Next, the spindle 6 is moved in the X-axis and Y-axis directions at predetermined intervals (for example, a pitch of 5 mm), and the distance in the Z-axis direction, that is, the distance to the workpiece A is measured at each position.

When the measurement is completed, this measured value is expanded on the X-axis, Y-axis, and Z-axis in the NC machining program, and then compared with the respective coordinates corresponding to the workpiece assumed in advance. .

Based on the result of this comparison, after modifying the machining program, the modification program is transferred to the numerical control section, and machining is started. For example, as shown by the phantom line in FIG. 2, the assumed dimension of the workpiece A from the predetermined position is 210 mm in the Z-axis direction, but when the actual measured dimension is 200 mm, this Z Axial corrections are made.

In practice, if the above correction method is adopted,
For example, what took 163 minutes of processing time was about 145 minutes including the measurement time of the object to be measured, and the processing time was reduced by about 10%.

For example, in addition to the processing of the outer shape, as described above, the cutting processing start position (point R) can be corrected to a position closer to the workpiece even in a fixed cycle such as drilling.

In the above embodiment, in order to measure the workpiece, the distance measuring device is attached to the spindle instead of the processing tool. However, for example, a CCD or the like is used to perform image processing to measure the workpiece. You may make it measure the distance or external dimension to a workpiece.

The method for modifying the NC machining program can be applied to, for example, a welding robot device.

[0024]

As described above, according to the program correcting method of the present invention, when the actually measured dimension is smaller than the assumed dimension of the workpiece, the processing start point is set at a distance corresponding to the dimension difference. Since the machining program is modified so that it comes closer to the side, the air cut can be reduced as much as possible,
Therefore, the processing efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a schematic side view of an NC machine tool used in an embodiment of the present invention.

FIG. 2 is a side view showing a measurement state of an object to be measured in the NC machine tool of the embodiment.

FIG. 3 is a flowchart illustrating a method for modifying an NC machining program according to the same embodiment.

[Explanation of symbols]

 A Workpiece 1 Machine tool 3 Mounting jig 4 Holding device 5 Processing tool 6 Spindle 8 Processing device 11 Distance measuring device

Claims (1)

[Claims] 1. An external dimension of a workpiece is measured with respect to an NC machining program that has already been created, and when the measured dimension is smaller than the machining dimension described in the program, the dimension difference is determined. A method for modifying an NC machining program, characterized in that the above-mentioned program is modified so that the machining start point comes closer to the workpiece side by a certain distance.