JPH02173564A - Ultrasonic flaw detector - Google Patents

Abstract

PURPOSE:To improve reliability by deciding a fact that there is a defect in a body to be inspected, when the number of continuous detections of a reflecting signal in plural directions exceeds a threshold. CONSTITUTION:An ultrasonic probe 1 of a linear array type is controlled by a processing control part 3 and scans a body to be inspected 5 in the width direction W, moves by a prescribed distance in the lengthwise direction L, when a measurement of a 1-line portion is ended, repeats the scan and inspects the whole body to be inspected 5. In this case, each receiving element of the probe 1 outputs a reflected echo signal as a receiving signal, and comparing parts 7-1 to 7-n compare the receiving signals from each element with a level threshold which is set in advance by a threshold setting part 9 and decide whether a reflected echo exists or not, and output it to a parallel - serial converting part 11. Subsequently, the converting part 11 converts a result of comparison inputted in parallel to a serial signal and supplies it to a counter 13, and the counter 13 counts the reflected echo signal inputted as a time series and decides whether a defect exists or not. Also, counters 17-1 to 17-n count reflected echo signals supplied through shift registers 15-1 to 15-n and can decide whether a defect exists or not.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an ultrasonic flaw detection device.

(Prior Art) An ultrasonic flaw detection device using ultrasonic waves is known as one of devices for non-destructively inspecting two objects to be inspected for defects. This ultrasonic flaw detection device emits ultrasonic waves at a predetermined frequency to the object while moving either the object or the ultrasonic probe and propagates them inside the object to detect echoes reflected by defective parts. The presence or absence of a defect is determined based on the size of the level.

Incidentally, in an ultrasonic flaw detection apparatus, the following determination method is used in order to prevent erroneous determinations due to electrical noise as various disturbances. In other words, since it is possible to detect defects by setting the pitch to be the smaller of the beam width of the ultrasonic beam or half the size of the defect to be detected, the pitch should be made even smaller. In some cases, a large number of reflected echoes can be obtained for one defect.

On the other hand, electrical noise is generally one-shot and does not occur continuously.

For this reason, a defect is determined when reflected echoes of a predetermined level or higher are continuously detected at a predetermined threshold value No or higher. According to this determination method, the threshold value N.

By appropriately setting , it is possible to perform a good judgment with excellent noise resistance. Note that the radiation frequency of the ultrasound in this determination method is determined by the directivity of the ultrasound beam, the size of the defect to be detected, and the relative speed between the subject and the ultrasound probe.

(Problem to be Solved by the Invention) However, in the above-mentioned determination method, since the determination is made based on reflected echo data in only one specific direction, defects spreading in the one direction (-dimensional) However, there is a problem in that high determination reliability cannot be obtained for defects that are two-dimensionally spreading or defects that are spreading in one direction different from the - direction. In addition, due to such a problem, the threshold value N.

It is also necessary to set the parameters in consideration of the various measurement conditions, making it difficult to set them appropriately.

The present invention has been made in view of the above, and its purpose is to provide an ultrasonic flaw detection device with high flaw detection reliability.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides an ultrasonic beam emitting means for emitting an ultrasonic beam to each part of one surface of a subject; reflected signal detection means for detecting a reflected signal exceeding a set level for each beam; a calculating means for calculating the number of consecutively detected reflected signals in a plurality of different directions with respect to one surface of the object; The object of the present invention is to include a determining means that outputs the presence of a defect in the object when the same value set in each of the plurality of directions is exceeded.

(Function) In the ultrasonic flaw detection device according to the present invention, the number of successive detections of reflected signals in different directions from one surface of the object to which the ultrasonic beam has been emitted is set corresponding to the plurality of directions. When the value exceeds the same value, it is determined that the object to be inspected has a defect.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

1 and 2 are a schematic configuration diagram and a main circuit block diagram, respectively, of an ultrasonic flaw detection apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a near-array type ultrasonic probe constituting an ultrasonic emitting means, which is scanned and driven in the width direction W of the subject 5 under the control of a processing control section 3 (not shown). The drive unit moves the subject 5 in a direction perpendicular to the length and width of the subject 5 while maintaining a constant distance from the subject 5.

In FIG. 2, reference numerals 7-1 to 7-n are comparison units constituting reflected signal detection means, and a threshold value setting unit 9 The preset level II I T
The presence or absence of a reflected echo is determined by comparing it with H, and the result is output to the parallel/serial converter 11. The parallel/serial converter 11 converts the comparison results inputted in parallel from each of the comparators 7 - 1 to 7 - n into a serial signal and supplies the serial signal to the counter 13 . The counter 13 counts the reflected echo signals from each of the comparators 7-1 to 7-n, which are input as time-series signals via the parallel-serial converter 11, to determine the presence or absence of a defect. It is. More specifically, this counter 13 receives a set number N+ of consecutive reflected echo signals from the comparison results by the comparators 7-1 to 7-n that are sequentially input as serial signals.
(For example, when 5) is counted, it is determined that there is a defect and a defect signal is output to a defect processing section (not shown). Note that the count value of this counter 13 is reset when there is no reflected echo signal and when a scanning drive start clock for the ultrasound probe 1 is supplied.

On the other hand, in FIG. 2, 15-1 to 15-n compare the comparison results from the connected comparison units 7-1 to 7-n in the longitudinal direction of the object 5 of the ultrasound probe 1. This is a shift register that shifts each time a movement command clock is input to the register and sequentially supplies the shifted most significant bit value to the counters 17-1 to 17-0 connected thereto.

Counters 17-1 to 17-n are shift registers 15-
The presence or absence of a defect is determined by counting the reflected echo signals from the corresponding comparison sections 7-1 to 7-n, which are supplied as time-series signals via the comparison sections 1 to 15-n. More specifically, the counters 17-1 to 17-n are configured so that the reflected echo signals are consecutively inputted from the shift registers 15-1 to 15-n, and the comparison results by the comparators 7-1 to 7-n are sequentially inputted from the shift registers 15-1 to 15-n. When a set number N2 (for example, 12) is counted, it is determined that there is a defect and a defect signal is output to a defect processing section (not shown). Note that this counter 17-
1 to 17-n, their count values are reset when there is no reflected echo signal and when a measurement start signal is supplied.

Here, the counters 13.17-1 to 17-n constitute calculation means and determination means.

Next, the operation of this embodiment will be explained using FIGS. 3 and 4. Note that FIGS. 3 and 4 are diagrams showing timing charts of processing in the width direction W and the length direction of the subject 5, respectively.

In FIG. 3, (A) shows the received signal waveform from each receiving element constituting the ultrasonic probe 1, and (B) shows the output waveform from the parallel-serial converter 11. Also,
In FIG. 4, (A) indicates h constituting the ultrasonic probe 1.
Ultrasonic probe 1 in the th (1≦h≦n) receiving element
The received signal waveform accompanying the movement of the subject 5 in the length direction,
(8) shows output waveforms from shift registers 15-1 to 15-n.

In the measurement, under the control of the processing control unit 3, when the measurement for one line in the width direction W of the subject 5 is completed by scanning drive of the ultrasound probe 1, the ultrasound probe 1 is next moved to the subject. The entire subject 5 is inspected by repeating the operation of moving the subject 5 a predetermined distance in the length direction of the subject 5 and then scanning and driving the subject 5.

Each of the receiving elements constituting the ultrasonic probe 1 outputs a reflected echo signal for the ultrasonic beam emitted every time it is driven as a received signal, but if there is no defect 19, the emitted Since there is no cause for reflecting the ultrasonic beam, the received signal level is approximately zero. Therefore, no reflected echo signals are output from the comparators 7-1 to 7-n, and therefore the counters 13 and 17-n
1 to 17-n, their count values never reach the respective it numbers Rtl N + and N2, so they are never determined to be defective.

However, if the object 5 has a defect 19, the emitted ultrasonic beam is reflected by the defect 19 and is received by the receiving element as a reflected echo signal with a certain high level (see Fig. 3). (A), see Figure 4 (A)). The comparators 7-1 to 7-n extract the received signals having a level exceeding the threshold TH from the received signals from the receiving elements, and convert the extracted signals to the parallel-to-serial converter 11 and the shift register 15- as reflected echo signals. 1 to 15-n.

The reflected echo signal input to the parallel-serial converter 11 is converted into a serial signal and supplied to the counter 13 (see FIG. 3(B)), and the counter 13 counts each time the reflected echo signal is supplied. Increment the number. In such a counting process, for example, as shown in FIG.
The two reflected echo signals in area (a) are caused by electrical noise, but in this case, the counter 13 is reset to 2 and does not output a defect signal. Next, the area (
Defect 1 for the 7 reflected echo signals in b)
In this case, the counter 13 can count up to 7, but will output a defect signal when the threshold value N(-5) is exceeded.

In this way, the presence or absence of the defect 19 in the width direction W of the subject 5 is determined based on whether or not the number of consecutive reflected echo signals reaches the threshold value N tubes.

On the other hand, the reflected echo signals input to the shift registers 15-1 to 15-n change from the lowest bit (LSB) to the highest bit ( MSB) and then supplied to the corresponding counters 17-1 to 17-n as time-series signals (see FIG. 4(B)).

The counter 17-h increments the count value each time a reflected echo signal is supplied. In such a counting process, for example, the area (a) and area (C
The reflected echo signal in ') is generated by electrical noise, but in this case, the counter 17-
h is reset after counting up to 2 and does not output a defect signal. Next, the reflected echo signal of 13gfA in area (b) of FIG. (=12), a defect signal will be output.

In this way, the defect 19 in the length direction 1 of the object 5
Regarding the presence or absence of
The determination is made based on whether the number reaches 2 or not. Note that similar processing is performed in parallel for the other counters 17-1 to 17-n (excluding 17-h).

From then on, the defect processing unit that receives the defect signal operates on the object 5.
Necessary defect processing will be carried out, such as rejecting the product as a defective product or notifying the user of the defect.

Therefore, according to the present embodiment, defect inspection is performed based on the generation state of reflected echoes in two directions perpendicular to each other, and according to criteria set individually for each direction. Defects that spread in either the width direction W or the length direction can be detected with high reliability while preventing erroneous determinations due to noise. Furthermore, the threshold value that serves as the determination criterion does not have to be as strict as the conventional one-way inspection, and can be set with a certain margin.

In this embodiment, the inspection directions are two directions, the width direction W and the length direction of the subject, but it goes without saying that the inspection direction and the number of inspection directions are not limited thereto.

Further, in this example, a linear array type ultrasonic probe was used, but it is also possible to arrange a large number of ultrasonic transducers, or to move one transducer mechanically. You can also do this.

[Effects of the Invention] As explained above, according to the present invention, the number of successive detections of reflected signals in a plurality of different directions with respect to one surface of the object to which the ultrasonic beam was emitted is determined by the threshold value set respectively corresponding to the plurality of directions. Since it is determined that the object to be inspected has a defect when the value exceeds this value, flaw detection can be performed with high reliability.

[Brief explanation of the drawing]

1 and 2 are a configuration diagram and a circuit block diagram, respectively, of an ultrasonic probe arrangement according to an embodiment of the present invention, and FIGS. 3 and 4 are diagrams for explaining the operation. 1... Ultrasonic probe 3... Processing control unit 5...
・Subject 7-1 to 7-n...Comparison part 9・
...Threshold setting section 1...Parallel/serial conversion section 3...Counters 5-1 to 15-n...Shift registers 7-1 to 17-
n...Counter 9...Defect

Claims (1)

[Claims] an ultrasonic emitting means for emitting an ultrasonic beam to each part of one surface of the object; a reflected signal detecting means for detecting a reflected signal exceeding a set level for each of the emitted ultrasonic beams; and one surface of the object. a calculation means for calculating the number of successive detections of reflected signals in a plurality of different directions; and a determination unit for outputting the presence of a defect in the object when the calculated number of consecutive detections exceeds a threshold value set respectively corresponding to the plurality of directions. An ultrasonic flaw detection device characterized by having means.