JPS62135735A - Vibration inspecting device - Google Patents

Abstract

PURPOSE:To execute a vibration inspection having a high accuracy, which is strong against a noise, etc., by providing a feature frequency extracting means for detecting an amplitude of a vibration in two or more frequency bands which are determined in advance, and a combination inspecting means for executing an inspection of an object to be inspected, from a combination of amplitudes in two or more frequency bands which are detected by this means. CONSTITUTION:A bead sound, etc. generated from electromagnetic operating parts 2 being an object to be inspected are detected by a microphone 4 and converted to an electric signal. The sound which is converted to the electric signal in such a way is amplified 6, and thereafter, A/D-converted 8, brought to a frequency spectrum analysis by an FFT circuit 10, and an amplitude by each frequency is known. Subsequently, a feature frequency extracting circuit 12 extracts only amplitudes of two frequency bands which are determined in advance in a frequency spectrum from the FFT circuit 10. A total of spectrums of these two feature frequency bands is compared with a pattern which is stored in a typical pattern storing circuit 16, by a pattern comparing circuit 14, and its result is displayed 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vibration testing device that non-destructively completes testing from vibrations occurring in an object to be tested.

[Prior Art゛( Conventionally, various inspection devices for non-destructively testing products have been proposed. A vibration inspection device is one of them.
Defects inside the object are inspected by photographing the object to be inspected.

The principle of vibration testing equipment is old and well practiced! The story begins with a person with a hearing impairment undergoing a hearing test.

To date, various methods have been proposed to save labor and automate this process. The easy ones are
Noting that objects with internal defects generate louder noises such as whining than normal objects, the amplitude of the object to be inspected,
There is a method that simply determines the quality of a product based on the so-called loudness of the sound. In addition, as a method for conducting inspections with higher precision, a method has been proposed in which the spectrum of one movement of the object to be inspected is analyzed and the inspection is performed by comparing the spectrum analysis results with the results of the spectral analysis of a normal object.

[Problem to be Solved by the Invention 1] However, the conventional vibration testing apparatus is still not satisfactory and often suffers from the following problems.

First, although it is inexpensive, it is extremely vulnerable to noise γ1 from the outside when it comes to simple tests based on the loudness of the sound.
If a loud sound enters as noise during the test, it will lead to a misjudgment. In addition, since the quality of the test can only be judged by a person or student, only binary test results such as pass/fail judgment can be obtained.

On the other hand, the method in which inspection is performed based on the results of frequency spectrum analysis of vibrations makes the above-mentioned disadvantages into advantages and has an advantage of 7.0. In other words, since the frequency spectrum analysis result of a normal object is compared with that of the object to be inspected, even if a whistling sound in a certain frequency band is mixed in, the effect on the inspection is minimal, and it is possible to detect specific internal defects. If the specific frequency at which the defect occurs is known, it is possible to detect the type and extent of the internal defect. However, the equipment is large and expensive, and requires complicated pattern recognition technology to compare spectrum analysis results, requiring a dedicated engineer or expensive logic circuits.

The present invention has been developed in view of the above-mentioned problems, and is therefore an excellent imaging inspection device that is resistant to external disturbances such as IlJ sound and can easily perform high-precision detection despite its simple configuration. The purpose is to provide.

[Means for solving the problems] The means configured by the present invention to solve the above problems are as follows:
As shown in the basic configuration diagram of FIG. 1, in a vibration inspection apparatus that detects vibrations occurring in an object to be inspected, and inspects the object to be inspected based on the detected vibrations, The object to be inspected is inspected using a combination of characteristic frequency extraction means C1 that detects amplitudes in two or more predetermined frequency bands, and amplitudes in two or more frequency bands detected by the characteristic frequency extraction means C1. The gist of the invention is a photographic inspection apparatus characterized by comprising a combination inspection means C2.

[Function] The characteristic frequency extraction means C1 in the present invention means that when an image of the object to be inspected f 2....fn) at 1-darin width (AI, A
2. ...Extract only An>. Here, the two or more predetermined frequency bands (fl, f2, . . . fn) are determined depending on the object to be inspected X and the inspection contents.

It is theoretically possible to know which frequency band of the imaging occurring on the object to be inspected is necessary as information for inspection, depending on the shape, material, or content of the object to be inspected. Or it can be determined experimentally. Therefore, by extracting only images captured in these frequency bands, the amount of information to be subjected to post-processing is narrowed down. This is done by limpling a desired frequency spectrum from the output of a well-known fast Fourier transform circuit (hereinafter simply referred to as FFT), or by detecting only the amplitude of a desired frequency band using a bandpass filter. Easily configured.

The silk matching inspection means C2 is the characteristic frequency extraction means C1.
The object to be inspected is inspected based on a combination of detection results. The combination U of detection results is the frequency fm
This is performed based on the results of m determinations, such as whether the amplitude Δm of (m = 1.2...n) is a person or smaller than a predetermined value Km. Therefore, a wide variety of judgments can be made, and extremely detailed inspections can be performed by theoretically and experimentally knowing in advance what kind of defects or failures are causing various combinations of vibrations.

EXAMPLES Hereinafter, in order to explain the present invention more specifically, the present invention will be described in detail by giving examples.

[Example] FIG. 2 is an electric circuit block diagram of an imaging inspection apparatus according to an example. When power is supplied to the electromagnetic operating component 2 as the object to be inspected, a humming sound or the like is generated from the core or the like. The microphone 4 detects this sound and converts the sound into a minute electrical signal. Note that in this embodiment, the microphone 4 is used because the noise frequency in the audible range is a problem, but it is also possible to capture low or high frequencies outside the audible range. Vibration Len 1J is used to efficiently pick up vibrations. The sound thus converted into an electrical signal is amplified by the next amplifier 6, and then Δ/
The D conversion circuit 8 converts the signal into a digital signal. And F
The frequency spectrum is analyzed by the FT circuit 10, and the amplitude at each frequency is determined. The feature frequency extraction circuit 12 is F
Only the amplitudes of two predetermined frequency bands are extracted from the frequency spectrum 1 to 1 from the FT circuit. In this embodiment, the frequency spectrum analysis performed by the FFT circuit 10 is output as a spectrum obtained by dividing the audible range by υ1 every 10 Hz, and the characteristic frequency extraction circuit 12 outputs a spectrum obtained by dividing the audible range by υ1 every 10 Hz.
The value obtained by adding the respective spectra (25 spectra) in two frequency bands of 0H7 and 17601-1 z to 2000 Hz is output. For example 260 Hz
~500 t (combiner 1 of spectrum up to z is 10 mV
, the total spectrum from 1760H7 to 20001-17 is 100 mV. This 2
The pattern comparison circuit 14 compares the sum of spectra 1 to n of the two characteristic frequency bands with the pattern stored in the typical pattern storage circuit 16. FIG. 3 is an explanatory diagram schematically showing the operations of the pattern comparison circuit 14 and the pattern storage circuit 16. As shown in the figure, if the measurement results of the inspected object are plotted with the vertical and horizontal axes representing the size differences of the spectra in the two characteristic frequency bands, it is clear to distinguish between non-defective products and defective products. The good/bad boundary line indicated by the dotted line in this figure is information stored in advance in the typical pattern storage circuit 16, and the pattern comparison circuit 14 compares in which region the current measurement Ii'+Song is located. to determine whether the product is good or defective.
Part 1 knee.

The east is output to the display circuit]8.

In this way, it is possible to easily determine whether a product is good or defective based on simple inspection tit two-dimensional information, that is, by combining the roughness of two 11-character frequency bands. Furthermore, even if noise from the outside enters the microphone 4, it is sufficient to determine the characteristic frequency in advance so that the determination operation is performed at a frequency other than the noise component, and highly accurate testing is possible.

In the embodiment, in the simplest case, only the determination of good and defective products is performed, or the at: ; The characteristic frequency extraction circuit 12 extracts the intense frequency of the pattern comparison circuit 1.
By comparing the two in step 4, it is possible to easily determine what kind of defect has occurred. At this time, check for each defective location! L’t! Extraction of type patterns and characteristic frequencies may be performed using a set of two or more optimal frequency spectra instead of two as in the previous section. Even if patterns are compared as a combination of two or more characteristic frequencies in this way, the judgment is much easier than when comparing all the frequency spectrum analysis results as patterns, and the time required for judgment is shortened and the processing circuit is Simplification etc. can be achieved.

However, in this example, the frequencies and characteristic frequencies most closely related to the item to be inspected are extracted from the photographic information of the object to be inspected, and subsequent information processing such as complicated pattern comparison is kept to the minimum necessary. Judgments are made based on combinations of characteristic frequencies, which are the amount of information.

Therefore, the circuit for performing information processing can be simplified, miniaturized, and reduced in cost while maintaining extremely high inspection accuracy comparable to that obtained by comparing all frequency spectra.

[Effects of the Invention] As described above in detail using the actual example, the vibration inspection device of the present invention detects vibrations occurring in an object to be inspected, and inspects the object based on the detected vibrations. (1) In the one-motion inspection device, a feature frequency extraction means for detecting one-line width in two or more predetermined frequency bands from the imaging, and two or more frequency bands detected by the feature frequency extraction means. The present invention is characterized in that a combination U inspection means for inspecting the object to be inspected is selected based on the combination of amplitudes at .

Therefore, highly accurate imaging inspection that is resistant to noise and the like can be realized with a simple configuration.

For this reason, it is necessary to provide portable, small-sized, high-performance imaging inspection equipment that was previously impossible, or to help automate the inspection process of scales. It will become.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is an electric circuit block diagram of an embodiment, and FIG. 3 is a schematic explanatory diagram of pattern comparison in the embodiment. C1... 1 sole frequency extraction means C2... Combination inspection means 10... FF lower circuit 12... Fatty frequency extraction circuit 14... Pattern comparison circuit

Claims (1)

[Scope of Claims] A vibration inspection device that detects vibrations occurring in an object to be inspected and tests the object based on the detected vibrations, comprising: characterized by comprising: a characteristic frequency extraction means for detecting the amplitude of the characteristic frequency extraction means; and a combination inspection means for inspecting the object to be inspected based on a combination of amplitudes in two or more frequency bands detected by the characteristic frequency extraction means. Vibration testing equipment.