JP2002333436A - Nondestructive inspection device of sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems of a conventional nondestructive inspection device of a sheet, which becomes in a large scale and highly accurate inspection is difficult. SOLUTION: An impact is imparted by a striking means 1 to the sheet W supported by a support means 2, and a sound pressure or a vibration generated by the impact is detected by a detection means 3. The detection signal is analyzed and plural characteristic quantity data are acquired therefrom by a calculation means 4, and the existence of a cracked defect of the sheet is determined from the characteristic quantity data by a determination means 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a simple structure,
The present invention also relates to a non-destructive inspection device that determines the presence or absence of a crack defect in a thin plate with high accuracy.

[0002]

2. Description of the Related Art As a prior art for performing nondestructive inspection of a thin plate, for example, in Japanese Patent Application Laid-Open No. 5-31792, an ultrasonic transducer is arranged in an array, an ultrasonic beam is transmitted by electronic scanning, and an amplitude value of a reflected signal is obtained. Is inspected for the presence or absence of cracks in the thin plate.

In Japanese Patent Application Laid-Open No. H10-82778, a thin plate is placed on a table provided with an air supply hole and an air intake hole, and air is sent out to the back surface of the thin plate to float a broken thin plate. When air is taken in, the thin plate is not adsorbed and the degree of vacuum does not increase. Therefore, it is determined that the thin plate has a crack.

[0004]

However, in the above-mentioned known example, Japanese Patent Application Laid-Open No. 5-322792 discloses that when a thin plate larger than the size of the ultrasonic array is to be inspected, it is necessary to move the ultrasonic array during the inspection. It has a complicated structure.

In Japanese Patent Application Laid-Open No. Hei 10-82778, the structure is simple. Is difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a nondestructive inspection apparatus which has a simple structure and which accurately determines the presence or absence of a crack in a thin plate.

[0007]

A first aspect of the present invention.
The thin sheet nondestructive inspection apparatus includes a supporting means for installing the thin sheet, a striking means for applying an external force to the thin sheet, and a detecting means for extracting one or both signals of sound pressure or vibration of a tapping sound generated from the thin sheet. Calculating means for analyzing a tapping signal extracted by the detecting means to obtain a plurality of feature data; and determining means for determining the presence or absence of a crack-like defect in a thin plate based on the feature data. And

According to a second aspect of the present invention, there is provided a non-destructive inspection apparatus for a thin plate according to the first aspect, wherein the supporting means supports the thin plate at any of three or four points from a back surface thereof and changes a supporting position with respect to the thin plate. It has a function to perform. The supporting position is determined so that the crack-like defect can be easily detected, and a single or a plurality of combinations are used.

According to a third aspect of the present invention, in the nondestructive inspection apparatus for a thin plate according to the first or second aspect, the striking means has a function of instantly applying an external force from the back surface or the front surface of the thin plate. The magnitude of the external force is determined so that the crack-like defect can be easily detected.

According to a fourth aspect of the present invention, there is provided a non-destructive inspection apparatus for a thin plate according to any one of the first to third aspects, wherein the calculating means performs time-frequency analysis of the signal taken out from the detecting means, and performs a This is to obtain feature amount data composed of the amplitude of the unit frequency component.

According to a fifth aspect of the present invention, there is provided a nondestructive inspection apparatus for a thin plate according to any one of the first to third aspects, wherein the calculating means performs rectification and envelope processing on the signal taken out from the detecting means, and performs unit time processing. This is to obtain feature amount data having each amplitude.

According to a sixth aspect of the present invention, in the non-destructive inspection apparatus for a thin plate according to any one of the first to third aspects, the calculating means analyzes the frequency of the signal taken out from the detecting means to obtain an amplitude for each unit frequency. Is used to obtain feature amount data.

According to a seventh aspect of the present invention, there is provided a thin plate nondestructive inspection apparatus according to any one of the first to sixth aspects, wherein the calculating means filters a signal taken out from the detecting means to remove an abnormal signal. The emphasis is used to obtain feature amount data.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a thin plate nondestructive inspection apparatus according to Embodiment 1 of the present invention. In the figure, W is a thin plate to be inspected. 1 is a striking means for applying an external force to the inspection target W, and is provided, for example, at the center of the inspection target. The hitting means 1 employs, for example, a mechanism that uses an air cylinder or the like as a driving source to cause a top provided at the tip to fly out by the force of pushing and to collide against the inspection target W from the back surface.

Reference numeral 2 denotes a support means for setting an inspection object.
For example, P close to the end face of the inspection target W ₁~ P₈In eight places
Provided. The support means 2 is an air cylinder.
The support position can be changed by driving the support point
A mechanism that can be changed is used. Support in case of three-point support
The position is, for example, P₁−P₃−P₇, P₁−P₅−
P ₆, P₂−P₆−P₈, P₃−P₄−P₈Of the four
From the combination, it is easy to detect cracked defects
Or determine a plurality of combinations. In addition, four-point support
The supporting position in the case is, for example, P₁−P₃−P₆−P₈,
P₂−P₄−P₅−P₇From the two combinations of
One or a combination of both to make it easier to detect
To decide.

Reference numeral 3 denotes detection means for extracting a tapping signal from the test object W. For example, a converter such as a microphone or a laser Doppler vibrometer, and an amplifier connected to the converter for amplifying the signal of the converter Circuit, a filter circuit connected to the amplifier circuit, for removing noise of the signal from the amplifier circuit and separating the signal into a plurality of frequency components, and an A / D connected to the filter circuit to capture the signal of the filter circuit It is composed of a conversion circuit.

Numeral 4 is a calculating means for analyzing the tapping sound signal extracted by the detecting means 3 to obtain a plurality of feature data.
For example, a CPU or DSP mounted on an electronic computer is used.

Numeral 5 is a discriminating means for discriminating the characteristic amount data obtained by the calculating means 4 and for judging the presence or absence of a crack-like defect in the inspection object W. For example, a neural network or the like is used.

The operation of the thin plate nondestructive inspection apparatus according to the first embodiment configured as described above will be described with reference to the flowchart of FIG. First, an inspection target W is prepared on the support means 2 (step S1). Next, it is determined whether to change the support position for the inspection target W (step S2). next,
A force is applied to the inspection target W by the striking means 1 (step S3).

Next, the tapping signal to be inspected is extracted by the detecting means 3, and the tapping signal is input to the calculating means 4 (step S4). Next, the hammering signal taken into the calculating means 4 is analyzed to obtain a plurality of feature data (step S5). Next, it is determined whether to change the support position for the inspection target W (step S6). When changing the support position, the process returns to step S2 in FIG. 2 to change the support position of the support means 2.
If the support position is not changed, the determination means 5 determines the characteristic amount data, and determines whether or not the inspection target W has a crack defect (step S7).

Here, the analysis of the signal by the tapping sound detecting means 3 generated by applying an external force to the actual test object W and the characteristic amount data of the signal will be described. First, here, it is assumed that feature amount data is obtained by short-time fast Fourier transform as one method of time-frequency analysis. FIG. 3 shows data of a thin plate having no crack-like defect, and FIG. 4 shows data of a thin plate having a crack-like defect. FIG. 3 (a) and FIG.
FIGS. 3A and 4B show the signals of the detecting means 3 in FIG. 3A, and short-time Fourier transform of these signals to obtain respective feature data. FIGS. 3 (c) and 4 (c) show an example in which the signal of the detection means 3 is filtered to emphasize the abnormal signal.

In the graphs of FIGS. 3A and 4A, the horizontal axis represents time, and the vertical axis represents voltage. The graphs of FIG. 3B and FIG. 4B show time on the horizontal axis and frequency on the vertical axis, and it can be confirmed that data by short-time fast Fourier transform is obtained in a matrix. . And
The level of the amplitude of the unit frequency component for each unit time obtained in the form of a matrix is represented by the shading of the color. The level is higher for a white color and lower for a black color. The graphs of FIG. 3 (c) and FIG. 4 (c) show time on the horizontal axis,
The vertical axis shows the voltage.

A range in which the difference between good and bad is large is extracted from the data obtained in this way, and input to, for example, a neural network. The presence / absence of a crack defect in the inspection target W is determined by learning the pass / fail pattern using the neural network.

Embodiment 2 FIG. In the first embodiment, the inspection target W is shown as a rectangular thin plate. However, the present invention is not limited to this. For example, a circular thin plate may be used. In this case, it is needless to say that the same effect as in the first embodiment can be obtained by disposing the support means 2 near the peripheral edge of the thin plate.

Embodiment 3 Further, in the first embodiment, the hitting means 1 is located at the center I of the inspection target W. However, the present invention is not limited to this, and may be at any place.

Embodiment 4 Further, in the first embodiment, the hitting means 1 is described as a mechanism in which an air cylinder or the like is used as a driving source to cause the top provided at the tip to fly out by the force of the pushing and collide against the inspection target W from the back surface. The present invention is not limited to this. For example, a mechanism that strikes the surface of the inspection target W with a hammer in which silicon rubber is attached to the tip of a rod may be used.

Embodiment 5 FIG. In the first embodiment, the support means 2 is described as a mechanism capable of changing the support position by driving the support point up and down by an air cylinder or the like. However, the present invention is not limited to this. 2 may be fixed to any of three or four locations, and a mechanism for changing the support position of the inspection target W by rotating the inspection target W may be used.

Embodiment 6 FIG. Further, in the first embodiment, the data based on the time-frequency analysis is shown as the feature amount data. However, the present invention is not limited to this.
The amplitude data per unit time by the rectification and the envelope processing or the amplitude data per unit frequency by the frequency analysis may be used as the feature amount data.

Embodiment 7 Further, in the first embodiment, the method of directly analyzing the signal by the detecting means 3 has been described. However, the present invention is not limited to this.
As shown in (c) and FIG. 4 (c), a method may be used in which a signal obtained by performing a filtering process and emphasizing an abnormal signal is analyzed to obtain feature amount data.

[0030]

As described above, according to the first aspect of the present invention, any one of the supporting means for installing the thin plate, the striking means for applying an external force to the thin plate, and the sound pressure or vibration of the striking sound generated from the thin plate. Detecting means for extracting one or both of the signals, calculating means for analyzing a hammering signal extracted by the detecting means to obtain a plurality of feature data, and determining whether or not there is a crack-like defect in the thin plate by the feature data. Since the determination means is provided, it is possible to obtain a non-destructive inspection apparatus which has a simple structure and determines the presence or absence of a crack-like defect in a thin plate with high accuracy.

According to a second aspect of the present invention, there is provided a non-destructive inspection apparatus for a thin plate according to the first aspect, wherein the supporting means supports at any one of three or four points from the back surface of the thin plate, and a supporting position for the thin plate. Therefore, it is possible to obtain a nondestructive inspection device that determines the presence or absence of a crack-like defect in a thin plate having a simple structure.

Further, in the nondestructive inspection apparatus for a thin plate according to the third aspect of the present invention, the hitting means has a function of instantly applying an external force from the back surface or the front surface of the thin plate. However, it is possible to obtain a nondestructive inspection device that simply determines the presence or absence of a crack-like defect in a thin plate.

According to a fourth aspect of the present invention, there is provided a non-destructive inspection apparatus for a thin plate according to any one of the first to third aspects, wherein the calculating means performs time-frequency analysis on the signal taken out from the detecting means, and performs a unit time analysis. Since the characteristic amount data including the amplitude of each unit frequency component is obtained, it is possible to obtain a non-destructive inspection device that determines the presence or absence of a crack defect in a thin plate with high accuracy.

According to a fifth aspect of the present invention, there is provided a non-destructive inspection apparatus for a thin plate according to any one of the first to third aspects, wherein the calculating means performs rectification and envelope processing on the signal taken out from the detecting means. Since the feature amount data having the amplitude per unit time is obtained, it is possible to obtain a non-destructive inspection apparatus that determines the presence or absence of a crack-like defect in a thin plate with high accuracy.

According to a sixth aspect of the present invention, in the non-destructive inspection apparatus for a thin plate according to any one of the first to third aspects, the calculating means analyzes the frequency of the signal taken out from the detecting means to obtain an amplitude for each unit frequency. Since the feature amount data is obtained, it is possible to obtain a non-destructive inspection device that determines the presence or absence of a crack-like defect in a thin plate with high accuracy.

According to a seventh aspect of the present invention, there is provided a non-destructive inspection apparatus for a thin plate according to any one of the first to sixth aspects, wherein the calculating means filters a signal taken out from the detecting means to filter an abnormal signal. Since the emphasis and the characteristic amount data are obtained, it is possible to obtain a nondestructive inspection apparatus that determines the presence or absence of a crack-like defect in a thin plate with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a thin plate nondestructive inspection device according to a first embodiment of the present invention.

FIG. 2 is a view showing a flowchart of an operation of the thin plate nondestructive inspection apparatus shown in FIG. 1;

FIG. 3 is a diagram showing data of a thin plate having no crack-like defect according to the first embodiment of the present invention.

FIG. 4 is a diagram showing data of a thin plate having a crack defect according to the first embodiment of the present invention.

[Explanation of symbols]

1 hitting means, 2 supporting means, 3 detecting means, 4 calculating means, 5 discriminating means, W thin plate, I hitting point, P1 to P8
Support point

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G047 AA06 AB04 BC04 BC07 CA03 CA07 EA10 GF10 GG12 GG17 GG19 GG25 GG37

Claims (7)

[Claims] 1. A supporting means for installing a thin plate, a hitting means for applying an external force to the thin plate, a detecting means for extracting one or both of a sound pressure and a vibration of a hitting sound generated from the thin plate, and the detecting means Calculating means for analyzing a tap sound signal extracted by the method to obtain a plurality of feature data; and determining means for determining the presence or absence of a crack defect in the thin sheet based on the feature data. Destructive inspection equipment. 2. The nondestructive inspection of a thin plate according to claim 1, wherein the support means has a function of supporting the thin plate at three or four points from the back surface thereof and changing a supporting position with respect to the thin plate. apparatus. 3. The non-destructive inspection apparatus for a thin plate according to claim 1, wherein the hitting means has a function of instantly applying an external force from the back surface or the front surface of the thin plate. 4. The apparatus according to claim 1, wherein said calculating means performs time-frequency analysis on the signal extracted from said detecting means, and obtains characteristic amount data comprising an amplitude of a unit frequency component per unit time. Non-destructive inspection equipment for thin plates as described in Crab. 5. The method according to claim 1, wherein the calculating means performs rectification and envelope processing on the signal extracted from the detecting means to obtain feature amount data having an amplitude per unit time. Non-destructive inspection equipment for thin plates as described. 6. The thin plate according to claim 1, wherein the calculating means performs frequency analysis on the signal extracted from the detecting means to obtain feature amount data having an amplitude for each unit frequency. Non-destructive inspection equipment. 7. The non-destructive thin plate inspection apparatus according to claim 1, wherein the calculation unit filters the signal extracted from the detection unit to emphasize an abnormal signal.