JPS58184544A - Ultrasonic flaw inspector - Google Patents

Abstract

PURPOSE:To enable fully automatic removal of reflected waves from the surface and bottom of a sample while allowing the extraction of waves reflected from defects with a gate circuit adapted to operate depending on the decisions of a decision circuit. CONSTITUTION:A decision circuit receives a clock pulse G and a detection signal L as input from a reflected wave detection circuit 23. At the rising of the clock pulse G, a lead signal with a width DELTAtr<DELTAT/2 is outputted to a memory circuit 25 to read out the frequency PN of the detection stored in the N address. At this point, according to an output level of the detection signal L, an updating frequency P'N is prepared and a light signal with a value P'N and a width DELTAtw (<DELTAT/2) is outputted to the memory circuit 25 to memorize P'N into a memory of the N address. Simultaneously, a decision signal O is outputted. The relationship between the output level VO of the decision signal 'O' and P'N is determined by the requirement of the Formula (where, VL represents the output level of the detection signal and Q a specified value). A gate circuit 26 outputs a signal pulse of a received signal I only when the output level VO of the decision signal O outputted from a decision circuit 24 is ''1''. This pulse serves as a defective pulse 11 of the signal I.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic flaw detection device that transmits and receives ultrasonic waves to obtain defect information, and in particular automatically erases reflected waves from the surface, bottom, etc. of a sample that are received after a certain period of time after transmitting ultrasonic waves. However, it relates to the process after ultrasonic transmission to extract only defective reflected waves.

There are two conventional methods for extracting only defect reflected waves.

The first method is a method for extraction using a fixed time gate. This is a method in which ultrasonic waves are received after a certain period of time has elapsed since the ultrasonic wave was transmitted, and then a predetermined period of time has passed since then, and nine reflected waves are extracted. Although this method is simple and widely used, the drawback is that the time gate position must be manually adjusted each time the sample thickness changes.

The second method is a method of extraction using a shifting time gate.

For example, when the thickness of the sample changes, the shape change of the sample is stored as a numerical value, and the time gate position is moved according to the value so that the bottom reflected wave of the sample is not extracted by the time gate. This method is convenient in that it can control the time gate by self-excitation, but it is inconvenient that numerical data for controlling the time gate must be created every time a sample with a different thickness is detected.

The purpose of the present invention is to eliminate the drawbacks of the conventional method of extracting defect reflected waves using time game (K), automatically remove reflected waves from the surface and bottom of a sample, and extract only defect reflected waves. It is an object of the present invention to provide a flaw detection device that can perform the following steps.

An example of ultrasonic flaw detection will be explained using FIG. 1. Probe 1
The ultrasonic beam 2 is transmitted while moving in the axial direction, and the reflected wave from the sample 3 is received. It is assumed that a defect 4 exists inside the sample 3, and that the thickness changes as shown by the bottom surface 6.7 of the sample.

Here, number 5 represents the sample surface. In the flaw detection shown in Figure 1, the signals received at positions X, , X, and X of the probe l are represented by A, B, and C in Figure 2, respectively. In the figure, the vertical axis represents the signal voltage, and the horizontal axis represents the elapsed time from the time of ultrasound transmission. At the probe position X1, an ultrasonic transmission pulse 8 and a reflected wave pulse 9 from the sample surface 5 (hereinafter referred to as surface pulse) are generated.

) and the reflected wave pulse 10 from the sample bottom rfi6 (hereinafter referred to as bottom pulse) t-received. At the probe position X, as shown by signal B, the transmitted pulse 8 at the signal person,
In addition to the surface pulse 9 and the bottom pulse 10, a reflected wave pulse 11 from the defect 4 (hereinafter referred to as defect pulse) is received. At the probe position 1i1tX, as shown by signal C, a transmitted pulse 8 and a surface pulse 9 are received. The reflected wave pulse 12 from the bottom surface 7 is received earlier in time than the bottom surface pulse 10 at the signal source because the sample thickness has become thinner. When comparing the signal person and signal B, the transmission pulse 8, the surface pulse 9,
It can be seen that the reception time of the bottom pulse 10 does not change.

The defect pulse 11 is received when the ultrasound beam from the probe impinges on the defect, and is no longer received as the probe moves. Comparing the signal person and signal C, it can be seen that the time position of the riL plane pulse changes. However, the bottom i
As long as the i17Km sound beam is irradiated, the time position of the bottom pulse 12 will not change even if the probe is moved from position X to the right.

As described above, even if the transmission pulse 8, the surface pulse 9, and the bottom pulse 10 and 12 are tested by moving the probe consonant to some extent, the reception time does not change, and the defect bar: ``.''.

When the probe is moved, the signal 11 suddenly receives or ceases to be received. Therefore, compared to the time position of the nine pulses received in the previous ultrasonic transmission, the pulse received at a different position becomes either a defective pulse or a bottom pulse when the bottom position changes. Whether it is a bottom pulse or not is confirmed because the time position at which it suddenly appeared does not change even after the next ultrasound transmission.

The above is the principle of the present invention. According to the present invention, by automatically extracting only defective pulses, it becomes possible to efficiently record and analyze defect information such as reception time, intensity, phase, and probe position of defective pulses at that time. In particular, in terms of recording flaw detection data, the capacity required to store flaw detection data is significantly reduced because data related to surface pulses and bottom pulses that are always received within the scanning range of the probe are not captured. .

The present invention was implemented as a turbine rotor flaw detection device.
state.

Figure 3 shows the scanning method for the turbine rotor and probe. In the figure, the probe 1 is brought into contact with the inner surface of the inner hole 15 of the turbine rotor 13 and moves spirally along the scanning direction 14. The ultrasonic beam 2 from the probe 1 is always emitted in the radial direction from the central axis of the turbine rotor.

The configuration of the flaw detection unit and lid is shown in Figure 4. In Figure 4,
Scanning device 20, scanning control device 721, probe 11 ultrasonic transceiver 22, analysis device 127Fi are commonly used devices, and are surrounded by dotted lines: reflected wave detection circuit 23, determination circuit 24, detection number storage circuit 25, The portion constituted by the gate circuit 26 is according to the present invention. The functions of each device will be explained below.

scanning! 111120 scans the probe 1 along the spiral scanning locus 14 in FIG. 3 in response to a control signal output from the scanning control device 21. In addition to controlling the scanning device 20 as described above, the scanning control device 21 outputs a drive pulse every time the probe 1 is scanned by a certain distance, and also outputs a drive pulse at the probe position coordinate (X) at that time.

Q) is output.

The ultrasonic transceiver 22 applies a transmission pulse synchronized with the drive pulse from the scanning control device 21 to the probe 1 to generate ultrasonic waves. It also has a function of amplifying and outputting the ultrasonic signal received by the probe 1.

The analysis device jt27 inputs the defective pulses extracted by the device marked by the dotted line and performs scanning control! The elapsed time from the time when the drive pulse is input from t+ff21 (that is, the ultrasonic wave transmission time) until the defective pulse is received, the intensity and phase of the defective pulse, and the probe position at that time are detected, and these data are stored. Using the stored data, analyze the location and size of the defect. In this embodiment, data is stored on a floppy disk.

Hereinafter, the functions of each circuit surrounded by dotted lines will be explained in detail.

The circuit configuration of the reflected wave detection circuit 230 is shown in FIG.

Synchronous pulse generator 121, clock pulse generator 6120
(AND game) 32, M-bit binary counter 70, voltage generator 100. The signal processing function of the edge trigger flip-flop 740 will be explained with reference to the tie chart shown in FIG.

The signal is a drive pulse. The synchronous pulse generator 121 outputs a pulse E having a width T in synchronization with the rising edge of the signal.

Here, T is a range expressed by the following equation with respect to the period ΔT of the clock pulse F output by the clock pulse generation m512G.

M×ノT＜T＜ (M+1)ΔT ・・・・・・(
1) In the AND gate 32, the 0M-bit binary counter 70 that outputs the AND pulse signal G of the signal E and the signal F is reset at the rising edge of the signal, and then counted at the falling edge of the signal G, and the value is stored as a time signal. Output as signal H. Signal■
represents the received signal. The voltage generator 100 generates a predetermined voltage VJ
Output. The comparator 130 outputs a voltage V of the signal I.
A signal K with the portion exceeding J set to TTL level "1'" is output. The edge trigger flip-prop 74 outputs a signal that maintains the output level of the signal at the falling edge of the clock pulse G as a detection signal. As described above, the reflected wave detection circuit 23 receives the signals G, H, and L as input signals.
Exit and play 1E.

Next, the function of the detection number storage circuit '2'50 will be described.

The detection count storage circuit 25 is an M-byte random access memory. Corresponding to the value NK indicated by the time signal H outputted from the circuit 23, the memory at location 9N4 becomes accessed.

When a read signal is input from the determination circuit 24, the memory contents at location Ni1 are output as a detection count signal to the determination circuit 24, and when a write signal is input from the determination circuit 24, the update count output from the determination circuit 24 is output to the memory at address N. Remember.

The function of the determination circuit 240 will be explained. In the judgment circuit,
A clock pulse G and a detection signal are input from the reflected wave detection circuit 23. Clock pulse G rising ΔT Width Δ1. By outputting a read signal of <- to the memory 2 circuit 25, the number of detections P)l stored in the Ni field is read. At this time, the number of updates P' is created according to the output level of the detection signal, and a write signal with a width Δtw (<ΔT/2) is stored in the storage circuit 25 as the value P'.
and the memory K P' at address N.

to remember. At the same time, a determination signal 0 is output. The relationship between the output level Vo and P' of the determination signal "0" is determined by the following conditions. However, VL is the output level of the detection signal, Q
indicates a predetermined value.

The gate circuit 26 receives the received signal IQ only when the output level VO of the determination signal O output from the determination circuit 24 is "1".
Outputs signal pulses. This pulse becomes defective pulse 11 of the signal engineer.

As described above, flaw detection was performed using the aWt which performs the nine functions, and it was possible to automatically remove nine bolts, the transmitted pulse 8, the surface pulse 9, and the bottom pulses 1o and 12, and to efficiently detect the defective pulse 11. Until now, since the bottom pulses 1° and 12 cannot be automatically removed, more than 200 floppy disks have been used to store flaw detection data in the analyzer 27 for flaw detection on a 12 m turbine rotor. There is a lot of use of floppy disks, and analysis Kl! There were times when I had more than 10 hours to do it. According to the present invention, only the defect information can be recorded on the floppy disk, so the number of floppy disks used is reduced to about two, and the analysis time can be significantly shortened to a few minutes.

The effects of the present invention can be summarized as follows.

1) When the thickness of the sample changes, defective pulses can be automatically extracted without moving the time gate position.

As a result, information on the bottom surface that is unnecessary for data analysis can be removed in advance, and data storage capacity and analysis time can be significantly reduced.

[Brief explanation of drawings]

Figure 1 shows the arrangement of the sample and probe. @Figure 2 is the probe position X,,X, in Figure 1. FIG. 3 is a diagram showing an ultrasound reception signal at X. FIG. 3 is a diagram showing a turbine rotor and a probe scanning method when the turbine rotor is inspected for flaws in an embodiment of the present invention. FIG. 4 is a diagram showing the arrangement of the present invention. FIG. 5 is a diagram showing the circuit configuration of the reflected wave detection circuit 230 in FIG. 44. FIG. 6 is a time chart showing one word processing in the circuit of FIG. 5. 20... Search S device, 21... Scanning control device, 22.
...Ultrasonic transceiver, 23...Reflection ujL detection circuit,
24... Judgment circuit, 25... Memory circuit, 26...
Gate circuit, author Z side (A) (B) (C) author 4 Fig.

Claims (1)

[Claims] 1. In a flaw detection device that transmits and receives ultrasonic waves to obtain defect information, there is a circuit that detects the presence or absence of reflected waves at fixed minute time intervals from the time of ultrasonic transmission, and a circuit that detects the presence or absence of reflected waves at every fixed minute time interval from the time of ultrasonic transmission. A circuit that stores the number of continuous receptions, a circuit that determines whether the number of times the reflected wave has been continuously received is less than a predetermined number of times, and a gate circuit that passes or cuts off the received reflected wave pulse based on the determination of the cough determination circuit. An ultrasonic flaw detection device characterized by automatically erasing reflected waves from the surface and bottom of a sample whose reception time does not change, and efficiently extracting only defect reflected waves.