JPS60181651A - Automatic calibration in ultrasonic flaw detection apparatus of pipe to be inspected - Google Patents

Abstract

PURPOSE:To enable automatic calibration, by automatically performing gate setting under an optimum condition corresponding to the shape of an actual pipe. CONSTITUTION:A beam distance Wth making the outer or inner surface flaw echo S12 of a welded part max. is calculated by a predetermined formula corresponding to the number of skips of a probe of which the position is set. Around the point on the CRT time axis of a flaw detection apparatus corresponding to said distance Wth, a flaw gate FG1 with predetermined widths a, b is set. A flaw gate start point pulse FGS1 is used in forming the gate FG1 and S11 is a surface echo. The comparison test piece collected from an actual pipe or each probe head is relatively moved to perform the calibration of sensitivity. In this case, a beam distance Wact, when the position of the probe is adjusted so as to make the flaw echo S12 max. in the comparison test piece, is different from the distance Wth of the predetermined formula. Therefore, a flaw peak position SP is detected and the width of the flaw gate starting point pulse FGS2 is widened by the shift amount delta with the distance Wth in the comparison test piece to move FG1 and a flaw gate FG2 is set to take out a flaw signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic calibration method for an ultrasonic flaw detection apparatus for a tube to be inspected, which extracts a defect signal by performing dart setting under appropriate R'f conditions according to the shape of the actual tube.

In general, ultrasonic flaw detection means for testing tubes, such as welded tubes,
As shown in the figure, two probes JA and J are placed at specific positions (skip positions) across the weld line 2 of the welded pipe 1 to be inspected.
C, 3B, and 3D, and a probe located on one of them, ? A, JC multiple ultrasonic beams 4°4 are applied to one inner and outer surface of the welded part 2a,
Similarly, the ultrasonic beams 4, 4 generated by the probes 3B, 3D located on the other side are applied to the inner and outer surfaces of the other welded part 2a.

For example, if a flaw detection waveform as shown in Fig. 2 is obtained using the flaw detection means with the probe arrangement ff1K as described above, the following dart settings are performed for the flaw detection waveform to obtain a defect signal. I'm taking it out. In other words, this dart setting means determines the time at which the defect signal (defect wave) at the skip position reaches its maximum for the feed probe 31.3B that is placed at one skip position from the weld line 2 and aims at the outer surface of the weld. An outer surface defect gate G1 of a predetermined width is set around a point on the axis, and for the temporary contactors 3C and 3D aiming at the inner surface of the weld part placed at a position of 1.57 kip from the twisted weld line 2, A defect signal is detected by setting an internal defect gate G2 of a predetermined width centered on a point on the time axis where the defect signal at the skip position is the highest. In Figure 2, Sl
is a surface echo, S2 is an external defect echo, and S3 is an internal defect echo. Wl.

The time it takes for the ultrasonic wave to reach the defect from the surface of the steel pipe,
In other words, it corresponds to the distance and is called the beam path11
．． Ru.

The arrangement of the probe and the dart setting means as described below are carried out prior to the calibration of the sensitivity of the flaw detection equipment and the setting of the defect judgment level, etc., and are usually carried out by the calibration operation procedure as shown in Figure 3. .

(1) First, reset the flaw detection conditions using A1 operation.

That is, in the calibration operation including the dirt setting of the flaw detection device,
Manually preset inspection criteria such as inspection dimensions, sensitivity, judgment level, use comparison defects, etc.

(2) Next, in operation A2, each of the contacts 3A to 3D is set at a predetermined skip position using a comparison test piece.

(3) Next, A3 manipulation? [Then, the probe position is adjusted so that the height of the defect echo of the control defect processed into the control test piece for each probe is maximized.

(4) In the A4 operation, dirt setting or correction of dirt setting is performed using the flaw detection waveform. That is, here, the outer surface defect dirt G1 and the inner surface defect gate G2 are set with a certain width centered on the defect echo S2.83. , the beam path lengths Wl, W for inner and outer defect detection
2 can be theoretically determined by the following equation.

(1) where D is the outer diameter, t is the wall thickness, θ is the superhair refraction angle, and n is the number of skips.

However, the above equation is a theoretical equation assuming that the tube to be inspected is a perfect circle], and actual tubes are not necessarily perfect circles and have uniform wall thickness, and the beam path that exhibits the maximum defect echo is determined by the theoretical equation (Equation (1)). The determined beam path WJ.

This will deviate from W2. Therefore, if the dirt settings have been made in advance through theoretical calculations, it is necessary to correct them at this stage.

(5) After performing the above operations, he performed operation A5 for automatic sensitivity calibration. This calibration involves relatively moving the comparison test piece or the probe head holding the probes 38 to 3D, and using the defect echo from the comparison defect to perform automatic calibration for sensitivity adjustment etc. through the batting order. Although it is understandable that operations 81 to A3 should be performed manually, there is a problem with the conventional technology in that the dart settings and dart theory settings for A4 operations are also manually corrected. There is. That is, it takes a great deal of time to manually set the darts for each pair of rod probes, and the increase in the calibration time including the dart settings is a major constraint on improving the operating rate of the flaw detection apparatus. Furthermore, as the wall thickness of the test tube increases, the number of probe pairs increases, and the conditions become worse.

In particular, with the recent demand for high productivity in pipe manufacturing, shortening the calibration time of ultrasonic flaw detection equipment has become a major issue to be solved.

The present invention has been made with attention to the above points, and provides a test tube that can automatically and quickly perform dart setting under optimal conditions according to the actual tube shape, and can be carried out continuously with automatic sensitivity calibration. An object of the present invention is to provide an automatic calibration method in an ultrasonic flaw detection device.

Next, the most important aspect of the method of the present invention will be explained with reference to FIG.

(1) First, after performing the operations A1 to A3 described above, dart setting is performed as follows. That is,
2-kip number r of the positioned probes 3^~3D (correspondingly, the beam path length wth at which the outer surface or inner surface defect echo S12 from the outer surface and inner surface defect portion of the welding part 2a is maximum
is determined by the theoretical equation (1). A defect y-to FG1 having a predetermined width a, b (for example, a=b=H skip phase beam path) is set centered on a point on the time axis of the cathode ray tube in the flaw detection device corresponding to the beam path wth.

When creating this defect dart) FGJ, the defect dart starting point A
? Lus FGS 1 is used. 811 is the front echo.

(2) Next, sensitivity calibration is performed by relatively moving the comparison test piece taken from the real tube or the probe head holding each of the probes 38 to 3D. In this case, the beam path length Wa c t when the probe position is adjusted so that the defect echo 812 of the comparison test piece is maximized as described above is (
1) It is different from the beam path length wth calculated by equation. , Therefore, the defect peak position SP is detected at the same time as the sensitivity adjustment is performed, and the deviation amount δ from the beam path length wth in the comparison test piece is determined.
I put it on.

(3) Next, the defect dart starting point pulse F by this deviation amount δ
By widening the width of GS2 and moving the defective dirt FG1, a defective gate FG2 is set and a defect signal is output.

Note that although the theoretical setting of the defect FC and the dart width at the time of its correction are shifted by the amount of deviation of the beam path length wth, it is assumed that the dart width differs depending on the shape of the defect to be inspected. That is, since the peak position of the defect echo 812 can be reliably detected by the defect echo FG 7 based on the theoretical f-1 setting, the defect echo FG 2 can be widened.
A dart setting is also possible.

Therefore, according to the automatic calibration method described above, it is possible to automatically perform the appropriate dart setting according to the shape of the test tube at the same time as automatic sensitivity calibration, avoid the complexity of the r-t setting, and Setting time can be significantly reduced. Therefore, considering that the calibration of ultrasonic flaw detection equipment is performed while the pipe production line is stopped, the expansion of automatic calibration can significantly reduce the required time, which has an extremely large effect on improving productivity. An automatic calibration method for a tube ultrasonic flaw detection device can be provided.

[Brief explanation of the drawing]

Figures 1 to 3 are shown to explain the conventional method, and Figures 1 (A) and (B) are top and side views when the probe is placed above the test tube. , Fig. 2 is a diagram showing the relationship between defective echoes and dart settings, Fig. 3 is a 70-chart showing the procedure of calibration operation, and Fig. 4 explains the dart automatic setting method which is the main part of the method of the present invention. It is a diagram. 1...Test tube (welded pipe), 2 river welding line, 2m...welded part, JA~3D...probe. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Commissioner of the Patent Office Manabu Shiga 1, Indication of the case, Patent Application No. 1983-37570 2, Title of the invention 3, Amendment Relationship with the Nagisa incident Patent applicant (412) Nippon Kokan Co., Ltd. 4, Agent 5, Voluntary amendment 7, Contents of the amendment As shown in Figure 1 of the drawing in red on the attached sheet, C = "3C" was changed to "
3D,” he corrected. Figure 1

Claims (1)

[Claims] Defect detection is performed based on the theoretical value of the first beam path that maximizes the defect signal from the defective part, depending on the dimensions of the test tube (including the comparison test piece) and the Sugit f number of the probe group set in position. A theoretical dart setting means for setting the temperature, and a second beam path is obtained by detecting the peak position of defect No. 411 during dynamic force sensitivity calibration, and the second beam path is derived from the first beam path. The position of the defective dirt is 6.
1. An automatic calibration method for an ultrasonic test tube ultrasonic flaw detection device vK, characterized in that it comprises a dart setting correction + stage for performing a dip gate setting by correcting 'I'.