JPS626164A - Ultrasonic inspection method for recesses corner part and its device - Google Patents

Abstract

PURPOSE:To detect exactly a crack-shaped detect, etc. existing in a working surface discontinuous part by discriminating an end part echo from the working surface discontinuous part and a reflected wave caused by a detect existing in its part. CONSTITUTION:An ultrasonic transmitter 4 sends out a transversal wave ultrasonic pulse beam as an ultrasonic wave IS to a recessed corner part 3. and an ultrasonic receiver 5 receives a reflected wave R. A control part 8 gives the instruction on a position to a scanning controller 7 of the receiver 5, gives the setting signal of a gate time for inputting a reflected wave corresponding to a position, to a receiver 9, and gives a timing signal to an oscillator 10. A receiving signal e(x) of the receiver 9 is divided by positive and negative of a position (x), an area S+ and S- are calculated by an area calculator 12, an area ratio S+/S- is calculated in a defect deciding device 13, its result is compared with a threshold value Sth and whether a defect exists or not is decided. Its result is outputted to an indicator 14 and a recorder 15. That is to say, from the form of a relative distribution of a receiving signal, an echo is discriminated and a defect is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an ultrasonic flaw detection method and apparatus, and more particularly to an ultrasonic inspection method and apparatus suitable for detecting defects present in various parts of an object.

[Background of the invention]

In conventional ultrasonic flaw detection methods, the presence or absence of defects has been determined based on the presence or absence of reflected waves. However, in places where the machined surface of the object is discontinuous, for example, in each concave part, reflected waves will occur if there is a defect, and even if there is no defect, waves will be reflected from each concave part to the end. There is a problem in that echoes are generated and this causes the recognition that a defect exists, which has been a major obstacle in performing ultrasonic flaw detection on the part concerned.

As a flaw detection method for such corners, for example, Japanese Patent Application Laid-open No. 5
As shown in Japanese Patent No. 9-141062, there is a method that focuses on differences in the waveforms of reflected waves. However, with such a method, it is only possible to determine whether or not there is a defect that forms a corner in the inspected part, and it is only possible to determine whether or not there is a defect in the corner of a concave object to be inspected, which is the object of the present invention. There is no indication of how to determine this.

[Purpose of the invention]

An object of the present invention is to provide an ultrasonic inspection method and apparatus that are effective in detecting defects even in discontinuous portions of a machined surface in view of the above-mentioned prior art.

[Summary of the invention]

The present invention deals with the occurrence of echoes from discontinuous parts of the machined surface,
This is based on the clarification of the differences between the echo generation situation when a rib-like defect exists in the part concerned, and by this, the edge echo from the machined surface discontinuity and the defect existing in that part. By distinguishing between the reflected waves and the reflected waves caused by the above-mentioned processing surface, it is possible to reliably detect wrinkle-like defects existing in the discontinuous portion of the machined surface.

[Embodiments of the invention]

Figure 1 shows the reflection state of ultrasonic waves at a concave corner, which is the basis of the present invention. (a) shows a model of the flaw detection method, and (b) shows a concave corner of the object. (c) shows the flaw detection result when there is no defect on the concave corner part, and (c) shows the flaw detection result when there is a defect on the concave corner. This is the level distribution.

In the same figure (a), machined surfaces 2a and 2b are discontinuous at a concave corner 3. At this time, ultrasonic waves, incident waves 1. When the beam is incident on the concave corner 3, if there is a crack-like defect 6 in the concave corner 3, an echo R will naturally occur. However, even if there is no crack-like defect 6 in the concave corner, a so-called end echo R will occur from the tip of the concave corner. becomes an obstacle.

Now, when a transverse wave ultrasonic wave is input from the probe 4 into the concave corner 3, it has been experimentally shown that the end echo from the concave corner 3 covers a wide directivity angle range. revealed. Therefore, when the probe 5 receives reflected waves R from the concave corner 3 at many positions on the surface la of the object, the distribution of received signal levels is as shown in FIG. −
The shape is almost symmetrical about the position O directly above the center. However, if there is a trap-like defect in the concave corner 3 that is almost perpendicular to the machined surface 2a, the received signal level when the probe 5 receives reflected waves R at multiple positions on the object surface la As shown in FIG. 3(c), the distribution of This method detects a defect in an object having a concave corner by utilizing the difference in the distribution form of the received signal level on the surface of the object.

Next, the principle of the inspection method according to the present invention for determining the presence or absence of a defect from the signal level distribution form will be explained. Figure 1 (b
), if there is no defect in the concave corner 3, the area S on the right side of the graph with the y-axis as the border.

and the area S on the left.

On the other hand, if there is a defect in the concave corner 3, as shown in FIG. 2(c), the area S on the right side,
is much larger than the area S- on the left side. Therefore, by examining the ratio S,=S and /i of S, and S, S,%1
Then, the reflected wave is an end echo from the concave corner 3,
It is determined that there is no defect, and if S,〉〉1, the reflected wave is an echo from the defect, and it can be determined that there is a defect. In reality, we set a threshold value S0 slightly larger than 1, and if S, < S, there is no defect, S? If ≧So, it is determined that there is a defect. 0 or more As shown above, in the present invention, defects are detected by distinguishing echoes not from the absolute value of the received signal but from the form of its relative distribution.

Next, an embodiment of an inspection apparatus for concretely carrying out the inspection method according to the present invention will be described with reference to FIG. 4 is a concave corner portion 3 that is inspected by a transverse ultrasonic pulse beam.
5 is an ultrasonic wave receiver that receives the reflected wave R from the concave corner 3, and 7 is an ultrasonic wave receiver that transmits the ultrasonic waves toward This is a scan controller for scanning. Reference numeral 8 denotes a control unit which gives an instruction of the scanning position to the scanning controller 7, gives a setting signal for a gate time for capturing reflected waves according to the scanning position to the receiver 9, and also gives a timing signal for ultrasonic oscillation to the oscillator 10. be. 11
takes in the position information from the control section 8 and the received signal level e(x) of the reflected wave detected by the receiver 9, and converts them into a focus! The area calculator 12 calculates the aforementioned areas S and S- by the area calculators 12a and 12b, respectively, and sends the results to the defect determiner 13. This defect determiner calculates the area ratio S and /S-, compares the results with the threshold value S□,
The presence or absence of a defect is determined using the determination method described above. The results are output to the display 14 and record 1115.

At this time, it is assumed that the wave receiver 5 is sensitive to longitudinal waves or transverse waves arriving from the concave corner portion 3 to be inspected. Also, in that case.

Since the wave receiver 5 is scanned, the reception angle of the reflected wave differs depending on one position, and the output of the wave receiver 5 is influenced by the directivity of the wave receiver 5. Therefore, if you use a wave receiver with directivity in a specific direction, for example, a vertical probe to receive longitudinal waves, or a Y-01 probe to receive transverse waves,
The received signal level distribution form shown in FIG. 1 is greatly influenced by the directivity of the wave receiver, and the directivity of one reflected wave itself has little influence on the form, making evaluation difficult. - For this reason, it is preferable to use a wave receiver with wide directivity so that its output corresponds to the directivity of the reflected wave.

As described above, according to the present invention, edge echoes from concave corners and echoes due to rib-like defects present in concave corners are distinguished, and defects in concave corners can be accurately detected. The reliability of the test can be increased.

The embodiments described above constitute an apparatus as one means for realizing the inspection method according to the present invention, and as long as the inventive idea of the present invention is utilized, it is not necessarily limited to this. In the above embodiment, one wave receiver is mechanically scanned in order to receive reflected waves at many positions on the surface of the object, but as shown in FIG. A large number of them may be placed on the surface of the specimen and scanned by electronically switching between them. Furthermore, the simplest method for achieving the effects of the present invention is to set the receiving position between two concave corners 3 of the object such that the received signal level is almost the same when there is no defect, as shown in FIG. By setting the two positions, defective echoes and edge echoes can be distinguished from the ratio of the received signal levels at the two receiving positions.
The spine of the defect can be easily detected. Especially in this case,
Devices such as the scanning controller 7R and the control unit 8 shown in FIG. 2 are not required, and the devices indicated by reference numbers 11, 12, and 13 are integrated into one and simply compare the two signal levels to determine whether there is a defect. It suffices to use a device that determines the
Pricing becomes possible.

In the embodiment described above, the distribution form of the reflected waves is determined by calculation, the presence or absence of a defect is determined based on this, and the result is displayed on the display device, so this method requires calculation. In Although.

However, by accurately capturing the directivity of one reflected wave, the above calculation becomes unnecessary. The inspection results that serve as the basis for this are shown in Figure 5.If there is no defect in the concave corner, the directivity of one reflected wave is almost isotropic, so Figure 5 (
As shown in a), the received signal level of the reflected wave on the surface has a gentle distribution, and reaches its maximum value almost directly above the concave corner.

On the other hand, if there is a defect in the concave corner, the maximum value is taken at a position shifted from the position directly above the concave corner, as shown in FIG. 5(b). This position can be predicted theoretically from the type of received wave and the shape of the reflection source, and the presence or absence of a defect can be determined by detecting that the maximum value of the received signal is near this position.

FIG. 6 shows the configuration of an apparatus that implements the above method.

The characteristic configuration of this device is indicated by the reference number 19.
receiving module. Adjacent modules are connected to each other in this receiving module, and its internal configuration is shown in FIG. 5 is a wave receiver whose refraction angle is adjusted to efficiently receive the reflected wave from the concave corner, and 9 is a receiver whose gate time for capturing the reflected wave is specified in advance, and is received in synchronization with a timing signal. Reference numeral 14 is a display device that takes in the output of the wave child 5, and 20 is a determiner that determines whether or not the received signal level of this module is at the maximum value. A method for determining the presence or absence of a defect using such an apparatus will be described in detail below. When we focus on the th module, let the received signal level of this module be e (k)
If e (k) is the maximum value, then k
-1st and +1st module received signal level e(
k-1).

When e (k+1), the following relationship exists.

e (k)≧e (k −1) --(3)
a (k)≦e (k + 1) −・=
(4) In other words, if the relationship expressed by this equation holds true, the received signal level e (k) to the module can be at its maximum value. Therefore, the determiner 20 determines whether or not the relationship expressed by this formula holds true, and if the relationship holds true, it is displayed on the display 14. Since it is sufficient for this indicator to simply indicate whether the relationship is established or not, it is sufficient to use a light emitting diode or the like. However, a problem with this method is that even if the relationship is established, the value may not be the maximum value but a local maximum value. However, such a problem can be solved if the display includes the magnitude of the signal level itself and is expressed by the intensity of light or the like.

As explained above, the above embodiment does not require complicated calculations, and can accurately detect defects in concave corners at high speed in real time using a simple device. .

〔Effect of the invention〕

As described above, according to the ultrasonic inspection method and apparatus of the present invention, it is possible to detect corners where it was difficult to accurately detect the presence or absence of defects due to the generation of edge echoes from the corners in the conventional method. This makes it possible to reliably detect defects occurring in the parts, especially wrinkle defects, thereby providing an inspection apparatus and method with superior detection performance.

[Brief explanation of drawings]

Figures 1 (a) to (c) are diagrams showing the corner inspection method that is the basis of the present invention and the distribution form of the received signal that is the basis of the present invention, and Figure 2 is an example of the inspection apparatus that is the present invention. Explanatory diagram of the enforcement police,
FIGS. 3 and 4 are diagrams showing the configuration of another embodiment of the present invention, and FIG. 5(a-). (b) is a diagram showing the basis of the inspection method in another embodiment of the present invention, FIG. 6 is a diagram showing the configuration of an embodiment of the inspection device based on FIG. 5, and FIG. 7 is the diagram shown in FIG. The figure which shows the structure of the receiving module used in the Example. 1... Subject, 2... Processed surface, 3... Corner, 4...
...Ultrasonic wave transmitter, 5...Ultrasonic wave receiver, 6...Cracked defect, porridge 1 figure 荊5 figure (α) Riko lol! 41 Midori 1

Claims (1)

[Scope of Claims] 1. An ultrasonic wave transmitter is provided at one position on the surface of the object having a concave corner, and ultrasonic waves are incident on the surface of the object to be detected toward the concave corner. A recess characterized in that the reflected waves from the recessed corner are received at a plurality of points, and the presence or absence of a defect at the recessed corner is detected from the distribution form of the received signal level on the surface of the object. Shaped corners and ultrasonic inspection methods. 2. In the method for ultrasonic inspection of a concave corner according to claim 1, the distribution of the received signal level of the received reflected wave on the surface of the subject is symmetrical about the concave corner. 1. An ultrasonic inspection method for a concave corner portion, characterized in that it is determined that there is a defect if the determination result is asymmetric. 3. In the ultrasonic inspection method for a concave corner according to claim 1, whether or not the maximum value of the received signal level of the received reflected wave exists at the position of the concave corner on the surface of the subject. A method for ultrasonic inspection of a concave corner, characterized in that it is determined that there is a defect if the maximum value is out of the position of the concave corner. 4. An ultrasonic wave transmitter that is positioned on the surface of the object having a concave corner and injects ultrasonic waves toward the concave corner of the object, and from a plurality of points on the surface of the object. A concave shape comprising an ultrasonic receiver for receiving reflected waves, and means for determining the presence or absence of a defect at the concave corner based on the distribution form of the received signal level from the ultrasonic receiver on the surface of the object to be inspected. Ultrasonic inspection device for corners. 5. In the ultrasonic inspection apparatus for concave corners as set forth in claim 4, the defect determining means determines the distribution of the level of the received signal from the receiver on the surface of the object to be inspected for the concave corners. It has means for performing calculations on the left and right sides of the center, and means for determining the presence or absence of a defect by comparing the calculation results from the calculation means. 6. In the ultrasonic inspection apparatus for concave corner parts as set forth in claim 5, the calculation means comprises an integrator. 7. In the ultrasonic inspection apparatus for concave corners according to claim 4, the defect determination means includes means for detecting the maximum value of the received signal level from the receiver, and An ultrasonic inspection apparatus for a concave corner, comprising means for determining a position at which a maximum level is received, and means for determining whether the maximum level reception position is at the position of the concave corner of a subject. 8. An ultrasonic inspection apparatus for a concave corner according to claim 4, wherein the ultrasonic receiver is scanned over the surface of the subject by a scanning means. 9. In the ultrasonic inspection apparatus for a concave corner according to claim 4, the ultrasonic receiver comprises a plurality of ultrasonic receivers disposed on the surface of the subject. Sonic testing equipment.