JPS5877432A - Detection of abnormality of tool in machine tool - Google Patents

Abstract

PURPOSE:To surely detect abnormality of a tool by dividing fequencies upon cutting process into low and high frequency distributing ranges of the tool of normal state, and by comparing these frequency components with each others. CONSTITUTION:Vibration of a tool is detected as an electrical signal by a detector 1, and the electrical signal is passed through a band-pass filter 2 in which flextion due to the vibration generated through a drive shaft or the like is eliminated. The output signal from the band-pass filter 2 is delivered to an arithmetic unit 3 in which autocorelating process is performed for obtaining a vibration frequency distribution. The output of the band-pass filter 6 is passed through a low-pass filter 4 and a high-pass filter 5 so that the output is filtered at a suitable frequency level. As the result, that is, after the ratio between vibration component values in both vibration distributing ranges is obtained by a comparator 6, whether the tool is normal or abnormal is determined in view of the value of the ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting tool abnormality in a machine tool.

Conventionally, tool abnormality detection in machine tools has been performed using electric power, Jl.
This was done by detecting an increase in width. However, these conventional detection methods are difficult to distinguish between normal and abnormal.
It has not been put into practical use yet.

In view of such problems, the present invention has been developed to solve the problem of tool abnormality vii.
This is a method that can actually detect the vibrations of the tool vII, and its characteristics are that it detects the vibration of the tool as an electrical signal during cutting, passes the signal through a band-pass filter '1, performs autocorrelation processing, and outputs the processed result using the filter. The ring divides the tool into a low frequency distribution area containing the most prominent frequency distribution wave in the normal condition 1IIK and a higher vibration distribution area, and /i! Damage to the tool can be detected by comparing r with the vibration component value by 1.

111) is a characteristic diagram of normal milling tool vibration when processed according to the above diagram, @3 Figure 1m) to (d)
It is a characteristic diagram when the vibration of a damaged milling tool is processed according to the above block diagram. First, normal tool vibration is detected as an electrical signal by the detection 61, and the signal is input to the bandpass filter 2, where the imaging deflection caused by the drive shaft etc. is removed.
3), the output signal is input to the arithmetic unit 3 that performs autocorrelation processing, and the frequency distribution is obtained here (see Fig. 2 (bj
ref), followed by

This output is passed through an l-pass filter 4 and a bypass filter S to an appropriate frequency level (II
3 II (see @)) (see Figure 3 (...)), the processing result, that is, the ratio of the vibration component values M and B in the two vibration distribution areas is obtained by the comparator 6, and based on that value, Determine whether it is normal or abnormal.

like this! & If the tool is applicable to a tool with a damaged ring, it is as shown in Fig. 3 ja) to td) K. The characteristics of the damaged tool are shown in FIG. 4 (-) by comparison with the IK311 (JF) characteristic diagram.

A normal tool can be determined to be a frequency distribution wave unique to the harpoon, while a distributed wave and a keel can be determined to be a newly generated distributed wave (
(Including distributed waves caused by normal tools) @ From this reason, @ Figure 3 (aJ, 'Ili 4
Figure (-) The moth in the normal state of the tool IIK also meets the bait distribution slope C with the prominent frequency distribution gc as the boundary a. The ratio B/mu with the vibration component value B is B/mu<l for a normal tool, and B/A>1 for a damaged tool.The determination of the number of shots level a, which is the boundary, is as follows. If the natural frequency distribution of each tool is almost the same, it is possible to settle the trap, but if the natural frequency distribution of each tool is different, it is necessary to assume that the tools are normal in advance. ftK, which can be determined for each tool.The frequency level a determined in this way is used to divide the signal output from the device 13 into a low frequency distribution area and a high frequency distribution area. In addition, in the embodiment, the determination of normality or abnormality is based on the ratio B/A of the frequency distribution wave in the low frequency distribution area and the vibration component value B in the high frequency distribution area. '
It is determined by whether it is larger or smaller than ll, but this limit is determined by the degree of machining n1 degree required.In order to maintain high machining accuracy, the value should be determined to be smaller than 1. .

As described above, according to the tool abnormality detection method according to the present invention, abnormalities caused by tool damage or the like can be detected more clearly.

[Brief explanation of the drawing]

Fig. 1 is a block diagram for implementing the tool abnormality detection method according to the present invention. , 5lN3 is a characteristic diagram when the vibration of a damaged plying tool is processed according to the block diagram in Fig. 1. ■...Detector, 2...Band pass filter, 3.
... Arithmetic device that performs autocorrelation processing %4 ... Rono (
Filter, medium bypass filter, 6... comparator. Applicant's agent Takahisa Kimura 2nd (0) (C) '' H2 Figure (b) (d) 2nd (0) (C) t'It Figure 1 (b) (d) Procedural amendment 1978 12 Director General of the Japan Patent Office 1, Indication of the Case 1982 Patent Application No. 147271 ・
2. Name of the invention Method for detecting tool abnormalities in machine tools 3. Relationship with the case of the person making the correction Patent applicant (123) Komatsu Ltd. 4, Agent (104) 2-11 Ginza, Chuo-ku, Tokyo No. 2 No. 6, Contents of amendment (1) Specification 1 [[First of all, ... Togieru] stated in the 19th line of the 2nd member to the bottom line of the 3rd member is corrected as follows. According to the method of the present invention, first, the vibration of the tool is detected by the detector IK.
Therefore, it is output as an electrical signal, and the signal is input to the /lyde pass filter 2 to remove deflection and the like caused by the drive shaft and the like. Then, the output signal of the filter 2 is subjected to autocorrelation processing in the arithmetic unit 3, and then the processing result is subjected to a cycle [1K analysis process] in the same arithmetic unit. l1RVh, the output of the arithmetic unit 3 is filtered through a low-nos filter 4 and a high-nos filter 5 using an appropriate bias maa as a boundary, which will be described later.
As a result of the processing, the ratio of the vibration components 1111A and B in the vibration distribution area lower than - and the value lower than that k is obtained by comparator a, and it is determined whether the tool is full or abnormal based on the ll1K. do. Assuming that the tool is now normal, the signal waveform shown in FIG. The analysis process yields the frequency distribution shown in FIG. 4(b). Therefore, when the frequency is set as shown in the above-mentioned vibration frequency (・), the filter 4 shows the case where the treatment shown in C is applied to a damaged tool, as shown in black below 1tl in the same figure. Engineering, 2nd (3rd-corresponding to liQ1m3~IdJ)
The results shown in (a) to ldl K are superior. Figure 3 (・
) in the distribution I[C, the 211th (including that shown in elk and the distribution direct) occurs in a frequency range higher than the boundary frequency a. (2) 1!1 shoe @ 4111g 1 line rs 3 m (
e), 41st m1e) Jt' rl12 @Jls)
-31k (Cth to UiEsk. 13) "Frequency level-" in the 8th and 13th lines of the same book is corrected to "frequency a" respectively. (4) Correct the "boundary level" in the 15th line and the 16th line of the same buttocks to "boundary [13!1 number"].

Claims (1)

[Claims] The vibration of the tool during cutting is detected as an electrical signal, and W
a*W: Auto-correlation processing is performed through a pan-pass filter, and the most prominent frequency distribution wave in the normal state of the tool is removed by the Asahi wet filtering, and the low frequency distribution area containing it is extracted. , and a higher frequency distribution range, and compare the values of each vibration component in both frequency distribution ranges to detect the value loss of the tool. Anomaly detection method.