KR20070105593A - Wear state monitoring of the blanking dies with acoustic signal - Google Patents

Abstract

A method of monitoring a wear state of a mold for a press through audible signal processing is provided to detect an erroneous audible signal caused by the abrasion or the breakage of the mold so that a worker recognizes the necessity of a polishing process to exactly cope with the situation. A sensor(1), which is able to detect an audible or vibration signal in a press during a blanking process, is installed on the bed of the press. Information on the signal detected by the sensor is delivered to a real-time monitoring system, so that the press is controlled and information is provided to a worker. A fixing groove is formed on the bed of a press machine to fix a housing. The sensor(1) is inserted into the housing and fixed by a screw. The abrasion or breakage of a mold is monitored in real time by frequency analysis of the signal using a low-pass filter and fast-Fourier transform(FFT).

Description

Wear state monitoring of perforated mold by acoustic signal processing {Wear state monitoring of the blanking dies with acoustic signal}

1 is an example of configuration of a real-time monitoring system of the present invention

2 is a vibration sensor of the present invention

3 is a specific example of the press blanking process of the present invention.

4 is a graph analyzing the acoustic signal (vibration signal) of the press blanking process of 30 million products of the present invention.

5 is a graph in which the acoustic signal (vibration signal) of the 90 million press blanking process of the product of the present invention is analyzed.

FIG. 6 is a graph in which the acoustic signal (vibration signal) of the 15 million press blanking process of the product of the present invention is analyzed.

<Description of Major Codes in Drawings>

1: sensor part 2: mold die

3: Bed

11: sound sensor (vibration sensor) 12: housing

13: Tightening sound sensor

In press processing, the state of the production die has an absolute influence on the product production quality, so a technique for real-time monitoring of the state of the mold is required. However, the criterion for the breakage or wear of the mold is inconsistent and inaccurate by the operator's experience.

The present invention relates to a method for determining a mold polishing cycle of press working using elastic wave and acoustic emission techniques. In the press working process, each process is accompanied by inherent vibration. Therefore, when abrasion or breakage of the mold or breakage of the material occurs, a unique abnormal signal is generated. In order to measure such a signal, an acoustic sensor (vibration sensor) is mounted on a bed of a press, and an acoustic signal (vibration signal) of abrasion or breakage of a mold generated during press processing is measured using an oscilloscope. The measured acoustic signal (vibration signal) can be monitored in real time using the high speed Fourier transform (FFT) method and the frequency analysis method using the low-pass filter.

In the press working process, the state of the production mold has an absolute influence on the product production quality, so there is an urgent need for a technology for monitoring the mold state in real time. Currently, the process management is difficult because it depends on the work experience. Accordingly, an object of the present invention is to determine the state of the mold through the signal detected by the acoustic sensor (vibration sensor) to determine the criterion of the polishing time or repair time of the mold, and to enable maintenance by the standard.

As shown in FIG. 1, the present invention detects an acoustic signal (vibration signal) generated during a press working process by a sensor attached to a bed. The acoustic sensor (vibration sensor) 1 is as shown in FIG. The acoustic sensor (vibration signal) fixes the housing 12 by digging a fixing groove in the bed of the press. Then, the sensor 11 is inserted into the housing 12 and then tightened with the tightening screw 13. Acoustic signal (vibration signal) received from the acoustic sensor (vibration sensor) 1 is monitored in real time through the fast Fourier transform (FFT) method and the frequency analysis method using the low-pass filter to reduce the wear or damage of the mold Monitor in real time.

3 is a press blanking process. (a) It is the point where the punch in the press touches the material. (b) The point at which plastic deformation of the material occurs due to the press punch. (c) It is the point where shear of material occurs by press punch. Blanking is a process that can have an absolute impact on the quality of the product. Observation and monitoring of this process reveals the polishing cycle of the mold.

4 is a graph analyzing sound signals (vibration signals) of 30 million press blanking processes of products. (a) It shows the magnitude of vibration signal over time. The flag shows the largest signal in the section where material deformation occurs. (b) Frequency-Amplitude graph of vibration signal over time by fast Fourier transform (FFT) method. (c) Frequency spectrum obtained by converting the vibration signal over time by the fast Fourier transform (FFT) method for a predetermined time.

FIG. 5 is a graph analyzing sound signals (vibration signals) of 90 million press blanking processes of products. (a), (b) and (c) are shown in FIG.

Fig. 6 is a graph analyzing the acoustic signal (vibration signal) of the 15,500,000 press blanking process of the product. (a), (b) and (c) are shown in FIG.

According to the present invention, it can be seen that the wear of the mold is increased by checking the characteristic frequency region of the blanking process, and the destruction type of the material is changed by increasing the noise region other than the characteristic frequency. That is, by measuring a certain sound signal (vibration signal) in the machining operation, it is possible to determine the criterion of wear and damage of the mold, to inform the operator when an abnormal signal occurs during machining, and to stop the operation of the press to prevent product defects.

As described above, the method for detecting the mold grinding time of the press working process of the present invention observes an abnormal acoustic signal (vibration signal) due to wear and damage of the mold during the machining process. By detecting the acoustic signal (vibration signal), the operator can be notified of the necessity of polishing, and the operation of the press can be stopped to quickly and accurately take action. As a result, the quality can be evaluated at the same time as the production of the product, it is useful to establish the automated process as well as the accuracy of the inspection process, and to establish a reliable production plan.

This invention is also applicable to various machine tools as well as presses.

Claims (1)

A sensor that can detect acoustic signals (vibration signals) in the press machining process is installed on the bed of the press to control the press and provide information to the operator through the real-time monitoring system of the acoustic signals (vibration signal) of the machining process. To detect mold and tool abnormalities

Images