JPH0487753A - Control method for nc machine tool - Google Patents

Abstract

PURPOSE:To improve a rate of operation of a machine by collectively measuring mounting accuracy of a plurality of workpieces, mounted a scale on a work table of an NC machine tool, before starting machining of the workpiece in the first machining order. CONSTITUTION:A pallet 4 is set up onto a work table 7, and mounting accuracy is measured with a measuring jig 6 by successively positioning each workpiece in a machining position. A machining program for a first workpiece n1 is called in a machine control unit 3 from an NC unit 2. In the machine control unit 3, a permissible limit of mounting accuracy of the workpiece, restricted in this machining program, is compared with the before-mentioned measuring result. In the case that the mounting accuracy is within the limit, machining is started on the workpiece n1. When the machining is finished, a machining program for the next workpiece n2 is called, and similarly to the case of the workpiece n1, the measured result of the mounting accuracy is compared with the permissible limit, restricted in the machining program, to start the machining when the accuracy is within the limit.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for checking the accuracy of a workpiece attached to a tombstone on a work table, which is performed as one of the preparatory steps for machining in an NC machine tool. This invention relates to improvements in control methods for processing procedures for workpieces.

[Conventional technology]

Normally, before machining a workpiece with an NC machine tool, setup work is performed to position and fix the workpiece with a predetermined accuracy on each side of a tombstone set on a pallet. Immediately before machining, when the pallet is placed on the work table, a measuring jig is attached to the main axis of the machine tool, and the accuracy of workpiece installation is checked (this is called "pass" measurement). If the position is off beyond the allowable range, processing is stopped or the installation is corrected.

[Problem to be solved by the invention]

Traditionally, this "street" measurement has been performed on the workpiece on each side of the tombstone immediately before the workpiece is machined. Therefore, multiple installations are required for tombstones with surfaces.
There was a risk that cutting waste or cutting fluid discharged from other workpieces due to previous machining would adhere to the accuracy measurement location of the unprocessed workpiece, causing errors in the actual measurement data. Of course, the workpiece is cleaned before measurement, but this work is quite tedious and complete cleaning cannot be expected. Many of them are judged to be defective, and are one of the causes of lower operating rates of machine tools.

The present invention solves these problems in the prior art, accurately measures the workpiece, and accurately determines how to process the workpiece based on the results and surrounding conditions. The purpose is to provide a method to improve machine availability.

[Means to solve the problem]

The purpose of this is to increase the precision of mounting multiple workpieces attached to tombstones on the work table of the NC machine tool in an NC machine tool that has a precision measurement function for workpiece mounting.
The workpieces in the first processing order are measured all at once before the start of processing.
Before starting machining of each workpiece, the measurement results are compared with a predetermined tolerance limit, and if it is within the tolerance limit, the machining is performed as is, and if it is outside the tolerance limit, a predetermined countermeasure is taken. NC characterized in that it is controlled to perform
This is achieved by the machine tool control method.

Preferably, the predetermined countermeasure process is to issue an alarm to notify the operator that the workpiece is improperly mounted during manned hours, and to skip machining of the workpiece during unmanned hours.

[Effect]

Conventionally, "on-the-spot" measurements were taken for each workpiece just before the start of machining, but in the present invention, measurements are taken while all workpieces on the worktable are unprocessed and uncontaminated by chips or cutting fluid. Regular measurements are taken and the data are stored in a suitable memory. Immediately before each workpiece is machined, measurement data for the workpiece is read out and compared with predetermined tolerance limits to determine whether the workpiece is properly attached.

If it is determined that the workpiece is properly attached, the workpiece is processed immediately. However, if it is determined to be defective, one of two options is selected depending on the surrounding situation at that time.

That is, during manned hours when an operator is present, an alarm is issued to notify the operator in charge that the workpiece has been improperly mounted. This allows the operator to check the mounting status of the workpiece again, and if it can be easily corrected, performs processing after correcting the mounting position and cover. However, if it is determined that it cannot be easily corrected,
Stops machining and skips to processing the next workpiece.

On the other hand, during unmanned hours such as late at night when the operator is absent, the procedure is skipped so that the next work is processed immediately without issuing an alarm.

According to the present invention, it is not only possible to accurately measure each workpiece and eliminate measurement errors caused by adhesion of foreign matter, but also to improve the operating rate of the machine tool by effectively involving the operator's judgment. It becomes possible to improve.

Hereinafter, the present invention will be explained in more detail based on preferred embodiments shown in the drawings.

〔Example〕

FIG. 1 is a block diagram showing an example of the configuration of an NC machine tool to which the method of the present invention is applied.
It consists of a C device 2 and a machine control device 3 provided with a memory interposed between the two.

FIG. 2 shows a state in which a workpiece is set on a pallet 4 on a worktable 7 at the front of this NC machine tool for machining. In this example, 4 works nl + n2
+ n=l The four mountings of the tombstones 5 with n4 mounted on the pallet 4 are positioned and fixed in a known manner on the surface. As mentioned above, these works nl +
n2 + n3. n4) The measurement jig 6 attached to the main shaft of the machine tool measures the accuracy (accuracy) of the attachment before starting machining of the workpiece n1 in the first machining order.

FIG. 3 shows a flowchart for carrying out a method for controlling a workpiece processing procedure according to the present invention.

According to the present invention, as a first step, first the work nI
+ n2 + n3 + The pallet 4 loaded with n4 is set on the work table 7, each work is sequentially positioned at the processing position, and the accuracy of the installation is measured using the measuring jig 6 attached to the machine tool. . The measurement results are stored in a memory within the machine control device 3 attached to the machine tool.

After completing the measurement of mounting accuracy for all the workpieces on the tombstone 5, the next step is to
The machine control device 3 reads the program of the workpiece n. The machine control device 3 compares the measurement result with the permissible limit of accuracy for mounting the workpiece specified in this Nitrogram. If the mounting accuracy is within the limit, machining of the workpiece n1 is started.

When the machining is completed, the machine program for the next workpiece n2 is called in, and as in the case of workpiece n, the mounting accuracy measurement results are compared with the tolerance limits specified in the machine program, and if it is within the limits. Processing is then started.

Thereafter, in the same manner, when the last workpiece n4 is processed, the entire work is completed.

However, if the installation of any workpiece is determined to be defective when comparing the accuracy measurement results and the allowable limits, the following two options are available depending on the environmental conditions at that time. It is set.

That is, in the case of manned hours when the operator is on duty, the warning lamp 8 attached to the machine tool is immediately turned on to notify the operator of the occurrence of a defective workpiece installation. This prompts the operator to rush to the site and personally confirm that the installation is defective. As a result, if the installation can be easily corrected, a manual command is given to continue processing after the correction.

However, if it is determined that it cannot be easily corrected, a manual command is given to stop the machining of this workpiece and skip to the processing procedure for the next workpiece. on the other hand,
During unmanned hours such as late at night, it is not possible to wait for the operator's decision, so a command is automatically issued to immediately stop processing the work and skip to the processing procedure for the next work. This control procedure can be summarized in a flowchart as shown in FIG. 3.

Note that the comparison of the workpiece attachment accuracy with the allowable limit may be performed for all the workpieces attached to the tombstone at once, immediately after the attachment accuracy is measured.

The above explanation is about the case where one NC machine tool has a built-in program, but the present invention is not limited to this, and multiple NC machine tools can be connected to a common host. The present invention can be similarly applied to a DNC system or the like managed by a combination network. In this case, the installation will not be able to store the accuracy measurement results or compare them with the allowable limit values.
done on the host computer.

〔Effect of the invention〕

According to the present invention, the mounting accuracy of multiple workpieces on the same tombstone is measured all at once before the start of machining, so measurement errors due to foreign matter adhering to the measurement surface are reduced, and incorrect mounting accuracy is measured. The probability of being judged as defective is drastically reduced.

In addition, by changing the treatment of workpieces determined to be defective during the manned and unattended periods, and by effectively involving the operator, workpieces determined to be defective were salvaged as much as possible. The operating rate of the machine can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of the configuration of an NC machine tool to which the method of the present invention is applied, and Fig. 2 is a perspective view showing a workpiece set on the front surface of the NC machine tool during street measurement. , FIG. 3 is a flowchart for carrying out the method for controlling a workpiece processing procedure according to the present invention. 1-Machine tool body, 2--NC device, 3-Machine control device, 4-Pallet, 5-Tombstone, 6-Measuring jig, 7-Work table, 8-Warning lamp, n+ + nt + nn + nn - work.

Claims (1)

[Claims] 1. In an NC machine tool having a workpiece mounting accuracy measurement function, the mounting accuracy of a plurality of workpieces mounted on tombstones on the work table of the NC machine tool is measured by processing the workpiece in the first processing order. The measurement results are measured all at once before the start of processing, and the measurement results are compared with a predetermined tolerance limit before the start of machining of each workpiece, and if the result is within the tolerance limit, the machining is carried out as is, and if the workpiece is outside the tolerance limit. 1. A control method for an NC machine tool, characterized in that control is performed so that predetermined countermeasure processing is performed when the problem occurs. 2. The predetermined countermeasure processing according to claim 1, wherein the predetermined countermeasure process is to issue an alarm to notify an operator of a workpiece installation failure during a manned time period, and to skip machining of the workpiece during an unmanned time period. Control method for NC machine tools.