JPS60127458A - Detecting apparatus of welded part - Google Patents

Abstract

PURPOSE:To attain the automation and capacity enhancement of a welded part detecting apparatus by enabling the leading-out of a reference pulse hight, by arranging comparing transmitting and receiving coils in the vicinity of measuring transmitting and receiving coils. CONSTITUTION:A vertical electromagnetic ultrasonic probe 11 is equipped with an electromagnet 12 for applying a DC magnetic field to a matrix material 1, a transmitting comparison coil 13s generating an ultrasonic wave, a transmitting measuring coil 13m, a receiving comparison coil 14s for detecting the reflected echo amount from the bottom surface of the matrix material 1 as a receiving signal and a receiving measuring coil 14m and, when the coils 13s, 14s are present at a position receiving no influence of a welded part 3, the coils 13m, 14m can correspond to the welded root part 3A or welding stop end position 3B of the welded part 3. The receiving output of the coil 14s is reduced by half by an attenuator 17 and the outputs of the coils 14m, 14s are applied to a differential circuit through differential operators 18m, 18s, and the pulse hight at the position receiving no influence of the welded part 3 and the crest value at the melting position of the welded part 3 are simultaneously detected and the melting position is detected from a position where each pulse hight comes to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a weld detection device using electromagnetic ultrasonic waves.
In particular, the present invention relates to a welded part detection device suitable for inspecting and managing welded parts of welded structures, and for performing welding work in conjunction with a welding torch.

Recently, with the automation of welding work, automatic inspection of the welding part, especially the penetration tip position or penetration toe position (hereinafter referred to as "penetration position") of the welding part, and determining pass/fail. A welding inspection machine was developed, and an automatic welding machine that performs welding by moving the welding torch along the welding line between two base materials is still called a welding machine (hereinafter referred to as "automatic welding machine").
) has been developed.

Among the automatic welding inspection machines and automatic welding machines mentioned above, for example, when welding two base materials m1 into a T-joint using an automatic welding machine, welding is performed with one base metal and the other base metal held at right angles. City teaching is performed by moving the torch along the welding line, and then a playback operation is performed according to the teaching content, so that welding work is performed while moving the welding torch along the welding line. However, in such automatic welding machines, if the bath tangent is long, even if the welding torch operates according to the teaching contents, the welding torch may deviate from the appropriate welding position due to distortion due to welding heat, or the base metal may be damaged. There is a problem in that the welding conditions cannot be adjusted to the size of the gap between the two, variations, etc.

In order to solve these problems, we use an ultrasonic weld detection device that projects ultrasonic waves onto the weld formed between the base metals and detects the penetration position of the weld from the amount of reflected echoes. By detecting the penetration position during welding or immediately after welding with the detection device, the detection result is input to the arithmetic processing device, and the welding torch is operated while adding correction calculations to the teaching contents to form a good weld. Things that do this have been known for a long time. As the above-mentioned ultrasonic weld detection device, there is a vertical 6 dB drop method using an ultrasonic probe.

Hereinafter, a conventional weld detection device using a vertical 6 dB drop method will be explained with reference to FIGS. 1 and 2.

In FIG. 1, reference numerals 1 and 2, which serve as the test object I, indicate base metals, and the base metals 1 and 2 are fixed to the bath contact portion 3 to form a T-joint weld. 4 indicates a vertical electromagnetic ultrasonic probe disposed on the base material 1 in a non-contact state; hereinafter referred to as "probe 4"
), a DC electromagnet 5 that applies a DC magnetic field to the base material 1 of the probe, and a DC electromagnet 5 that is located between the electromagnet 5 and the base material 1 and generates ultrasonic waves in the base material 1 by applying pulses. The receiving coil 7 is located below the transmitting coil 6 and detects the amount of echoes reflected from the bottom surface of the base material 1 as a received signal. Reference numeral 8 denotes a pulse generator that applies a high-frequency pulse to the transmitter coil 6, 9 an amplifier that amplifies the received signal from the receiver coil 7, and 1o a processing circuit provided at the next stage of the amplifier 9. The processing circuit 1o has a function of determining the penetration position of the welded portion 3 from the signal level of the received signal. In addition, in FIG. 1, 3A indicates a weld root portion which is the penetration tip position of the weld portion 3, and 3B indicates a weld toe portion which is a contact point between the weld portion 3 and the monthly 1.

In the welding part detection device configured as described above, when the transmitting coil 6 is excited with a predetermined pulse from the pulse generator 8 while the DC electromagnet 5 is excited to apply a magnetic field to the base material 1, the base material 1 is excited. An eddy current flows on the surface of the base material 1, and a Lorentz force based on Lemming's left-hand rule acts on the base material 1, generating mechanical displacement (ultrasonic waves). This ultrasonic wave propagates perpendicularly from the surface of the base material 1, is reflected from the bottom surface of the base material 1'1, and returns to the surface side again, so the returned ultrasonic wave is sent to the receiving coil 7 through the reverse process of generation. The welded portion 3 can be detected by receiving the voltage signal as a voltage signal and further determining the received signal by the processing circuit 10 via the amplifier 9.

That is, when the centers of the transmitting coil 6 and the receiving coil 7 that constitute the probe 4 are at a position A away from the welding part 3, the amount of reflected echo from the bottom surface of the base material 1 is as shown in FIG.
It's in A. Next, the probe 4 is gradually moved from this point RA toward the welding root portion 3A, and when it comes to a position B corresponding to the welding root portion 3A, the reflected echo scattering WB at that time is w.
It decreases to 1/2 of A (-6 dB). Next, when the probe 4 is moved from this position B to the central part of the welded part 3, most of the ultrasonic waves are transmitted through the welded part 3, and the amount of reflected echoes Wc at that time decreases by more than Wn. Furthermore, when the probe 4 is moved from this position C to a position corresponding to the weld toe 3B, the amount of reflected echoes becomes equal to Wn again, and from this position to the position E, which is distant from the welding part 3. When moved, the amount of reflected echoes becomes equal to wA again. Thus, probe 4
The position of the welding root part 3A can be determined by moving it from an appropriate position A toward the welding part 3 and searching for a place where the amount of reflected echo is WA/2 using the processing circuit 1o. The detection method is conventionally known as the vertical 6 dB drop method. On the other hand, the weld toe 3B can also be detected in the same manner.

In this way, even in the welding part detection device according to the conventional technology, the transmitting coil 6 and the receiving coil 7 adjust the peak value of the received signal at a position away from the welding part 3 (hereinafter, this peak value is referred to as the "reference peak value"). On the other hand, by detecting the position showing -6 dB, the weld root portion 3A or the weld toe portion 3B can be detected.

However, in the conventional technology, the standard wave height value varies greatly due to changes in the material, plate thickness, surface condition, etc. of the base material 1. For this reason, every time the material, shape, etc. of the base metal 1 to be welded is changed, it is necessary to check the standard wave height value at a position (position A or F in Fig. 1) that is not affected by the welding part 3 in advance. There is a drawback that it cannot be used.

The present invention was made in view of the drawbacks of the prior art described above, and detects the wave height value at a position not affected by the welding part and the wave height value at the penetration position of the welding part almost simultaneously, and detects the wave height value of both. It is an object of the present invention to provide a welding part detection device capable of detecting the penetration position from a position where is zero.

In order to achieve the above object, the feature of the configuration adopted by the present invention is that a pair of transmitter/receiver coils are provided between the electromagnet that applies a DC magnetic field to the test material and the test material, and the output of one transmitter/receiver coil is An attenuator that attenuates the received signal level by approximately half is provided on the side, and an arithmetic unit is provided on the output side of the other transmitting/receiving coil and the attenuator to perform differential calculations on the received 4N signals. The welded portion is detected by finding the position where the difference between the two multiplied signals becomes zero.

Hereinafter, the present invention will be explained based on the embodiment shown in FIGS. 3 to 5. The difference from the prior art is that base materials 1 and 2 are fixed to each other by a welding part 3, forming a T-joint weld. However, there is no such thing.

However, 11 indicates a vertical electromagnetic ultrasonic probe used in the present invention (hereinafter referred to as "probe 11"), and the probe 11 includes a DC electromagnet 12 that applies a DC magnetic field to the main body, and A transmission comparison coil 1 is located between the electromagnet 12 and the base material 1 and generates ultrasonic waves in the base material 1 by applying pulses.
33 and the transmitting measurement coil 13m, and each coil 13
A receiving comparison coil 148 is located below s, 13m and detects the amount of echoes reflected from the bottom surface of the base material 1 as a received signal.
and a receiving measurement coil 14m. Then, each of the comparison coils 138° 148 and the measuring coil 1
3m and 14m are spaced apart from each other by a predetermined distance, and each of the comparison coils 138 and 148 is separated from the welding part 3.
Each measuring coil 13 m when in a position not affected by
, 14m can be set at a position corresponding to the weld root portion 3A or weld toe position 3B of the weld portion 3.

15 is a comparison coil for transmission 13s1 measurement coil for transmission 13
a pulse generator for applying a predetermined 41 rus to m, 168
．． 16m is an amplifier that amplifies the received signals from the receiving comparison coil 149 and the receiving measuring coil 14m. Is 17 amplified? ,? The attenuator 17 is provided at the next stage of r16S, and the attenuator 17 has the function of attenuating the level of the received signal from the receiving comparison coil 148 inputted via the amplifier 168 by approximately 50 dB, that is, 6 dB. have 1881
18m is a waveform shaping circuit provided at the next stage of the attenuator 17 and the amplifier 16m, and the waveform shaping circuits 1.88.18. y
Based on the maximum peak value of the voltage signal detected by the receiving comparison coil 1dll and the receiving 61 constant coil 14m, the waveform is shaped into a rectangular wave signal according to the peak value. In addition, the waveform shaping circuit 188.18m includes:
a dart circuit that opens the gate for a predetermined dart time necessary to capture the signal in synchronization with the signal from the pulse generator 15; and a peak hold circuit that holds the highest peak value during the dart time. is built in as required.

19 is a differential circuit provided at the next stage of each waveform shaping circuit 1811.18m, and this differential circuit 19 subtracts the input from each waveform shaping circuit 18s and 18m, and outputs a signal of the difference between both signals. It has the function of

A processing circuit 20 processes the output from the differential circuit 19. In addition, when the welding part detection device of the present invention is applied to an automatic welding inspection machine, the processing circuit 20 is an inspection monitor or recording device, etc. for determining the pass/fail of the welding part 3, and when applied to the automatic welding machine. In this case, it corresponds to a correction calculation device for feedback that operates the welding torch while correcting the difference signal from the differential circuit 19 with respect to the gray bar 7 signal according to the teaching content.

The present invention is constructed as described above, and its operation will now be described.

First, as shown in FIG. 4(a), the case where the receiving comparison coil 14B1 of the probe 11 and the receiving measuring coil 14m are located at a position not affected by the welding part 3 is shown in FIG. 5(a).
This will be explained with reference to the characteristic diagram.

In this case, in a state where the DC electromagnet 12 is excited and a magnetic field is applied to the base material 1, the nosolus generator 15 as shown in FIG.
As shown in FIG. 1, a positive current is output and supplied to the transmitting comparison coil 13.1 and the transmitting measuring coil 13m. As a result, ultrasonic waves are generated in the base material 1, and the receiving comparison coil 14
B is the first reflected wave pi reflected from the bottom surface of the base material 1, the second reflected wave
A reflected wave P 2 , a third reflected wave P3, and a gradually attenuating voltage signal are received, and this received signal is amplified by an amplifier 16s and output as a comparison signal as shown in FIG. 5(b). At this time, since the receiving comparison coil 148 is located away from the welding part, the peak value of the first reflected wave pl at this time is E. In addition, the receiving comparison coil 14m is also the base material 1.
The first reflected wave reflected from the bottom surface of P1% second reflected wave (11
P 2 , the third reflected wave P3, and a gradually attenuating voltage signal are received, but since the receiving measuring coil 14m is also located away from the welding part 3, the amplifier 16m receives the voltage signal shown in FIG.
) is output, and the peak value of the first reflected wave p of the measurement signal is E.

On the other hand, the comparison signal from the amplifier 168 is processed by the attenuator 17 so that the peak value is half (-6 da), that is, the first reflected wave Pl becomes the peak value of V2, as shown in FIG. 5(e).
It outputs the attenuated signal P'(+P'2 r P's) shown in FIG.

Next, the attenuated signal from the attenuator 17 is transferred to a waveform shaping circuit 183.
The waveform shaping circuit 188 is input to the pulse generator 1.
The dart is opened for a predetermined dart time necessary to capture the attenuation signal in synchronization with the mother pulse from 5 (for example, the time corresponding to the attenuation signal p/l), and the first reflected wave P1 with the highest peak value is detected. The peak value V2 of the attenuated signal p/l corresponding to is held at the peak, and a rectangular wave signal of pulse time T is outputted at a peak value E/2 as shown in FIG. 5(d). Similarly, amplifier 1
The measurement signal from 6m is also input to the waveform shaping circuit 18m,
The waveform shaping circuit 18m opens the dart for a predetermined dart time in synchronization with the pulse from the pulse generator 15, peak-holds the wave height value E of the first reflected wave P, which has the highest wave height value, and As shown in Figure (f), a rectangular wave with a peak value E and a pulse time T is output.

Next, each waveform shaping circuit 18. ．． The output from the waveform shaping circuit 18m is input to a differential circuit 19, which performs a differential operation of subtracting the output of the waveform shaping circuit 18a from the output of the waveform shaping circuit 18m.

By the way, when the probe 11 is in the position shown in FIG. 4(a), the output of the waveform shaping circuit 18m is higher than E
Since the peak value is high by /2, the differential circuit 19 is as shown in FIG.
As shown in g), the differential signal of peak value E/2 is processed by the processing circuit 2.
Output to 0.

Thus, when the processing circuit 20 is applied to an automatic welding inspection machine, the position of the weld 3 is monitored while moving the weld detection device according to the present invention in the direction of the weld line in conjunction with the movement of the welding machine, Record on the inspection monitor or recording device that the weld root section 3A of the weld section 3 does not exist at the position shown in Figure 4 (a), and from the collection of these records, it can be determined that the weld section 3 is not present at the position shown in Figure 4 (a). Determine pass/fail. On the other hand, when the processing circuit 20 is applied to a fully automatic welding machine, the welding part detection device according to the present invention is moved in the welding direction in conjunction with the welding torch while supervising the welding route part 3A, and the welding torch is moved as shown in FIG. A correction calculation is performed to move from the position shown in (a) to the position shown in FIG. 4 (b).

Next, as shown in FIG. 4(B), for the case where only the receiving measurement coil 14m of the probe 11 is present directly above the welding route 3A of the welding part 3, the case shown in FIG. 5(B) is as follows. This will be explained with reference to the characteristic diagram.

In this case as well, since the receiving comparison coil 148 is located at a position where it is not affected by the welding part 3, the comparison signal from the amplifier 16°, the attenuated signal from the attenuator 17, and the waveform shaping circuit 188
There is no change in the rectangular wave signal etc. from the above case, as in the case described above.

However, the receiving measuring coil 14m is connected to the welding route 3A.
Since it is located directly above the receiving measuring coil 14 m.
The amount of reflected echoes received by
dB). As a result, the detection voltage values of the first reflected wave pi, second reflected wave P2, and third reflected wave P3 received by the receiving measurement coil 14m are also halved, and the measurement signal output from the amplifier 16m is as shown in FIG. As shown in (e), the wave height value of the first reflected wave P is E/2.

Then, the first reflected wave Pl is waveform-shaped by the waveform shaping circuit 18m, and has a wave height E as shown in FIG. 5(f).
/2, outputs a rectangular wave with pulse time T.

The waveform shaping circuit is8. The tube wave signal from the ism is input to the differential circuit 19, which performs a differential operation of subtracting the output of the waveform shaping circuit 188 from the output of the waveform shaping circuit 18m. By the way, when the probe 11 is in the position shown in FIG. 4(b), the waveform shaping circuit 18s.

Since the peak values of the rectangular wave signals output from 18m are both V2, the difference signal from the differential circuit 19 is as shown in FIG. 5(g).
As shown in FIG. 2, the signal becomes zero, and no signal is input to the processing circuit 20 during the predetermined reference time T.

Thus, when the processing circuit 20 is applied to an automatic welding inspection machine, the welding route portion 3A is located at the position shown in FIG. 4 (+').
Record the existence of the test on the inspection monitor or recording device. On the other hand, when the processing circuit 20 is applied to an automatic welding machine, it is determined that the welding torch is moving along the welding line, and the welding is performed without adding any correction calculation to the play/%'tsuku signal. Continue the welding operation with the torch.

In this manner, in this embodiment, the peak value E of the comparison signal serving as the reference peak value and the peak value of the measurement signal can be determined simultaneously for the same base material 1.

Therefore, as in the prior art, the material of the base material 1, which is the material to be detected,
There is no need to measure and store the reference wave height value each time according to plate thickness, surface shape, etc., and it is possible to promote complete automation of automatic welding inspection machines, automatic welding machines, etc.

In addition, in the embodiment of the present invention, the transmission comparison coil 1
3g and the receiving comparison coil 1411 are specific examples of one transmitting/receiving coil, and the transmitting measuring coil 13m and the receiving measuring coil 14m are specific examples of the other transmitting/receiving coil.
A single transmitter/receiver coil may be used as both a transmitter coil and a receiver coil, and in this case, the DC electromagnet 12 and the base material 1
1&I], the comparative transmitting/receiving coil and the measuring transmitting/receiving coil may be arranged separated by a predetermined distance.

On the other hand, in the embodiment, the horizontal base metal 1 and the vertical base metal 2 are T-jointed welded, but the present invention is not limited to this and can be applied to butt welding, patch welding, lap welding, etc. On the other hand, when the welded portion is on the upper surface side of the base metal, the probe 11 may be placed on the lower surface side (r).

Furthermore, although automatic welding inspection machines, automatic welding machines, or welding robots have been described as examples to which the present invention is applied,
It is widely applicable to devices that detect welds and require predetermined viewing or feedback control.

Since the welding part detection device according to the present invention has been described in detail above, it achieves the following effects.

■ In the conventional technology, it is necessary to measure the reference wave height value in advance at a position unaffected by the weld every time the material to be detected changes. Since a transmitter/receiver coil is provided and the signal received by the comparison transmitter/receiver coil can be used as a reference peak value, automation of the welding portion detection device can be promoted.

■ Since a non-contact type electromagnetic ultrasonic probe is used as the ultrasonic probe, a piezoelectric vibrator such as a crystal vibrator or a turtle 71 vibrator such as barium titanate can be used as an ultrasonic transducer. Compared to those using type vibrating consonants, there is no fluctuation in the received signal level due to contact pressure, a stable signal can be obtained, and the reliability of the device can be improved.

■ In relation to item 0 above, a contact type vibrator can only be applied to the material to be detected at room temperature, but if an electromagnetic or ultrasonic vibrator is used, it can be applied even at high temperatures during or immediately after welding. It can be easily linked with automatic welding machines, etc.

■ Since the difference between the measurement signal and the comparison signal is calculated, the penetration position of the weld can be detected with high accuracy.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional weld detection device, Figure 1 is an explanatory diagram of its principle, and Figure 2 is the amount of reflected echoes at positions A, B, C, D, and E in Figure 1. FIGS. 3 to 5 show the weld detection device according to the present invention, FIG. 3 is its overall configuration, and FIG. An explanatory diagram showing a moved state,
FIG. 5 shows waveform characteristic diagrams at probe positions (a) and (b) in FIG. 4. DESCRIPTION OF SYMBOLS 1, 2... Base metal, 3... Welding part, 3A... Welding root part, 3B... Welding toe part, 11... Probe, 1
2...DC electromagnet, 13. ...transmission comparison coil,
13m...transmission measurement coil, 14. ...Receiving comparison coil, 14m...Receiving measurement coil, 15...
No9 Luss generator, 163116m...Amplifier, 17.
...Attenuator, 183. 18m... Waveform shaping circuit, 19... Differential circuit, 2
001, processing circuit. Patent Dejima Hitachi Construction Machinery Co., Ltd.”00,1 σ \-/ \-〆 \,ノ \-/

Claims (1)

[Claims] In a welding part detection device that detects a welded part of the tested material based on a DC electromagnet that applies a DC magnetic field to the tested material and a received signal level of the electro-ultrasonic wave, a pair of the transmitting and receiving coils are provided. , an attenuator is provided on the output side of one transmitter/receiver coil to attenuate the received signal level by approximately half, and an arithmetic unit is provided on the output side of the other transmitter/receiver coil and the attenuator to perform differential calculations on the received signals from these. 1. A welding part detecting device, characterized in that the welding part detection device is configured to detect a welding part by finding a position where a difference between both multiplied signals becomes zero using the arithmetic unit.