JPH0376866B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an ultrasonic flaw detection device using an array type probe for flaw detection of steel pipe welds. Concerning ultrasonic deflection angle adjustment method.

[Conventional technology]

Oblique ultrasonic flaw detection using an array type probe is used to detect flaws in steel pipes. As shown in FIG. 3, an array type ultrasonic probe 10 is mounted on a steel pipe 20.
The gap between the steel pipe 20 and the probe 10 is filled with an ultrasonic medium such as water, and the phase is sequentially applied to a plurality of transducers of the probe 10, for example, three transducers 1, 2, and 3. Apply a delayed pulse voltage to generate ultrasonic wave l ₁ , and then generate ultrasonic waves l ₂ and l ₃ in the same manner,
These ultrasonic waves are incident obliquely in the thickness direction of the steel pipe 20, and the reflected waves are received by the same probe 10 for flaw detection. Each transducer group 1, 2 and 3, 4 and 5
When a pulse voltage with the same phase difference is applied to Incident angle θi of each ultrasonic wave to the steel pipe 20
(i=1, 2, 3,...) are different, and the refraction angle θ _R that goes into the steel pipe 20
It also becomes different.

Since it is preferable that all the refraction angles used in angle angle flaw detection are constant, the refraction angle θ _R and therefore the incidence angle θi (i=
1, 2, 3,...) are all the same, it is necessary to change the deflection angle α. The deflection angle α can be changed by the phase of the pulse voltage applied to the transducer group, and αi (i = 1, 2, 3, ...) that makes θi (i = 1, 2, 3, ...) the same is the steel pipe. and the array type probe (i.e., for example, the probe 1 in the X-Y coordinate system with the origin at the center O of the steel pipe)
0 center position and the inclination of its ultrasonic transmitting/receiving surface, the number of transducers in the transducer group and their spacing, the outer diameter R of the steel pipe)
I'm looking for it.

[Problem that the invention seeks to solve]

However, the steel pipe 20 is not necessarily a perfect circle, and if it is not a perfect circle, the above calculation will be incorrect, and the ultrasonic waves will not be able to properly aim at the welded part. Steel pipes (UO pipes) are made by bending a steel strip from both the left and right edges to make a U-shaped cross section, then bending it further to make an O-shape, and welding the butt parts to make a steel pipe with a circular cross section. It tends to come off and protrude outward. If the steel pipe is non-circular, the angle of incidence θi will be incorrect, which in turn will cause the angle of refraction θ _R to be incorrect, but the latter deviation is quite large.

To explain this using Figure 4, the ultrasonic propagation velocity is
When an ultrasonic wave is incident from a medium of C ₁ at an incident angle θi,
The ultrasonic propagation velocity enters the medium at C ₂ at the refraction angle θr, and there is a relationship between them: C ₁ · sin θr = C ₂ · sin θi. Assuming the medium is water and the medium is steel.
If C ₁ is 1480 m/s, C ₂ is 3230 m/s, and θi is 25.5°, then θr = 70°. Here, the incident angle θi is displaced by 1° and
When it becomes 26.5°, θr=76.9°. In other words, if the angle of incidence changes by 1°, the angle of refraction changes by 6.9°, leaving the flaw detection range.

The present invention has been made in view of this point, and is intended to enable accurate flaw detection of welded parts.

[Means for solving problems]

When an ultrasonic flaw detection device using an array type probe is used to detect flaws in a welded steel pipe, the present invention applies a pulse voltage whose phase is sequentially delayed depending on the outer diameter, wall thickness, and desired refraction angle of the steel pipe. The ultrasonic wave is transmitted to the transmitting array type probe, the ultrasonic wave reflected within the steel pipe is received by the receiving array type probe, and from the sound field distribution of the received ultrasonic wave, it is determined that the ultrasonic wave inside the steel pipe is This method is characterized by adjusting the deflection angle of the ultrasonic waves transmitted from the transmitting array probe to a state where the scattering of the ultrasonic waves is minimized.

[Effect]

Prior to flaw detection of a welded part, a pulsed voltage with a phase determined by the outer diameter, wall thickness, and desired refraction angle of the steel pipe is successively delayed is applied to the transmitting array probe to transmit ultrasonic waves, and the ultrasonic waves reflected within the steel pipe are detected. From the sound field distribution of the received ultrasound received by the receiving array type probe,
By adjusting the deflection angle of the ultrasonic waves transmitted from the transmitting array type probe so that the scattering of ultrasonic waves within the steel pipe is minimized, accurate welding can be achieved even if the steel pipe weld is non-circular. It is possible to perform flaw detection.

〔Example〕

FIG. 1a shows a state in which scattering of ultrasonic waves within the steel pipe is minimized. FIG. 2 shows the configuration of an ultrasonic flaw detection apparatus to which the present invention is applied, in which 30 is an ultrasonic transmitter that applies a pulse voltage to each vibrator of the transmitting array type probe 10, and 31 is an ultrasonic transmitter that applies a pulse voltage to each vibrator of the transmitting array type probe 10; This is an ultrasonic receiver that receives the pulse voltage generated by the 40 is a calculator that calculates the deflection angle α in the manner described above, and further calculates the delay time of each vibrator necessary to obtain this deflection angle α.
The signal is applied to an ultrasonic transmitter 30 and an A/D converter 32 through the transmitter. The ultrasonic transmitter 30 has a delay time controller 34
The phase of the pulse voltage applied to each vibrator is changed in accordance with the delay time given by the A/D converter 32 on the receiving side, and the signals are added together in the digital adder 33. The addition result is converted into analog by the D/A converter 35 and displayed on the waveform display 36.

However, although the calculation of the delay time assumes that the steel pipe is a perfect circle, the actual steel pipe is not necessarily a perfect circle, and if it is not a perfect circle, the result will be incorrect, so ultrasonic waves inside the steel pipe The refraction angle of is no longer constant.

Therefore, in the present invention, the arrangement is as shown in FIG. 1a. That is, the transmitting array type probe 10 and the receiving array type probe 10' are arranged symmetrically, the transmitting array type probe 10 transmits ultrasonic waves, and the ultrasonic waves reflected within the steel pipe are transmitted. The ultrasonic wave is received by a receiving array type probe 10' and the sound field distribution of the ultrasonic wave is detected. In FIG. 1a, when an ultrasonic wave 11 is transmitted from the transmitting array type probe 10 to a steel pipe 20, and the refraction angle of the ultrasonic wave within the steel pipe is constant, the ultrasonic wave is reflected within the steel pipe. Since there is little scattering, the sound field distribution of the ultrasonic waves received by the receiving array type probe 10' becomes as shown in FIG. 1b. On the other hand, the ultrasonic wave 12 is transmitted from the transmitting array type probe 10 to the steel pipe 20,
If the refraction angle of the ultrasonic waves within the steel pipe is not constant, there will be a lot of scattering of the ultrasonic waves reflected within the steel pipe, so the sound field distribution of the ultrasonic waves received by the receiving array type probe 10' will be Figure c.

Therefore, the deflection angle α generated by applying to the transmitting array type probe a pulse voltage whose phase is determined by the outer diameter, wall thickness, and desired refraction angle of the steel pipe is successively delayed.
The ultrasonic wave is transmitted with the deflection angle changed around this, and the deflection angle and thus the phase delay amount are adjusted so that the sound field distribution of the received ultrasonic wave becomes as shown in FIG. 1b.

〔Effect of the invention〕

As explained above, in the present invention, prior to flaw detection of a welded part, a pulse voltage whose phase determined by the outer diameter, wall thickness, and desired refraction angle of the steel pipe is sequentially delayed is applied to the transmitting array type probe to generate ultrasonic waves. The ultrasonic waves that are transmitted and reflected within the steel pipe are received by the receiving array type probe, and the ultrasonic waves that are transmitted and reflected within the steel pipe are received by the receiving array type probe. By adjusting the deflection angle of the ultrasonic waves transmitted from the array type probe, accurate flaw detection of the weld zone can be performed.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a means for minimizing the scattering of ultrasonic waves within a steel pipe, Fig. 2 is a block diagram showing the configuration of an ultrasonic flaw detection device to which the present invention is applied, and Fig. 3 4 is an explanatory diagram of the steel pipe flaw detection procedure using an array type probe, and FIG. 4 is an explanatory diagram of the incident angle and refraction angle. In the drawing, 10 is a transmitting array type probe, 10'
is a receiving array type probe, 20 is a steel tube, 30 is an ultrasonic transmitter, 31 is an ultrasonic receiver, 32 is an A/D
Converter, 33 is a digital adder, 34 is a delay time controller, 35 is a D/A converter, 36 is a waveform display, and 40 is a calculator.

Claims (1)

[Claims] 1 In an ultrasonic flaw detection device using an array type probe for angle-angle flaw detection of steel pipe welds, the transmitting array type probe is sent to a position determined by the steel pipe dimensions and flaw detection conditions, the receiving array type probe is placed, and the transmitting array type probe is Ultrasonic waves are transmitted from the probe into the steel pipe, and the ultrasonic waves reflected within the steel pipe are received by a receiving array type probe.The sound field distribution of the received ultrasound waves shows that the scattering of the ultrasound waves inside the steel pipe is A method for adjusting the deflection angle of an array type probe, comprising adjusting the deflection angle of ultrasonic waves transmitted from a transmitting array type probe to a state where the amount of ultrasonic waves is minimized.