JP2009156648A - Measuring gap adjusting method and apparatus in ultrasonic flaw detection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring gap adjusting method in ultrasonic flaw detection for regulating the measuring gap between a measuring target and a sensor to the optimum gap, and a measuring gap adjusting instrument in ultrasonic flaw detection. <P>SOLUTION: The measuring gap adjusting method in ultrasonic flaw detection comprises the step of arranging the measuring target between a probe on the transmission side and a probe on the receiving side to transmit ultrasonic waves from the probe on the transmission side and to receive them by the probe on the receiving side to detect the internal flaw of the measuring target, thereby correcting the measuring gaps between the respective probes and the measuring target preset from the flaw detection data of the measuring target by measuring the transmission wave, surface wave and base wave from the measuring target. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for adjusting a measurement gap in ultrasonic flaw detection, in which defects inside a steel plate are detected by ultrasonic flaw detection.

  Until now, the ultrasonic flaw detection method for internal defects in steel plates has been widely used for water gap type and water column type ultrasonic flaw detection methods using shoe contact materials, which are widely used for thick steel plates, and for thin steel plates, tire probes have been used. There are a flaw detection method used, a submerged type, and a water column type flaw detection method. And as for the measurement gap, there are known a method of setting a gap with a steel plate by a shoe or the like, and a method of performing a water column or a submerged type fixed gap.

  In particular, when performing an internal flaw detection on a thin steel sheet, if a fine defect (φ0.1 mm or less) is to be detected, the method using a tire probe lacks the defect detection capability (generally φ1 mm or so). Therefore, there is a problem that measurement is difficult. Further, in the submerged type or water column type method for detecting fine defects, there is a limitation in the measurable plate thickness when the gap is fixed to the steel plate.

Thus, for example, there is a technique disclosed in Patent Document 1. In this technology, a water column type ultrasonic flaw detection apparatus and method for raising and lowering a sensor via a sensor raising and lowering means and variably setting a gap with a steel sheet to maximize a defect echo height from an internal defect quickly and accurately. Is disclosed.
Japanese Patent Laid-Open No. 2007-170901

  However, even when the gap is variable as in the technique disclosed in Patent Document 1, a waveform setting error or gap positioning error occurs, and the waveform is not optimal and the predetermined flaw detection performance is not achieved. There was a problem.

  An object of the present invention is to provide a measurement gap adjustment method and apparatus in ultrasonic flaw detection that adjusts a measurement gap between a measurement object and a sensor to an optimum gap in view of these problems of the prior art.

  According to the first aspect of the present invention, a measurement object is disposed between a probe on the transmission side and a probe on the reception side, and ultrasonic waves are transmitted from the probe on the transmission side to detect the probe on the reception side. A measurement gap adjustment method in ultrasonic flaw detection, in which an internal defect of a measurement target is detected by receiving with a probe, wherein each of the probes and the measurement target set in advance from the flaw detection information of the measurement target The measurement gap adjustment method in ultrasonic flaw detection is characterized in that the measurement gap is corrected by measuring a transmission wave, a surface wave, and a bottom wave from the measurement object.

  According to claim 2 of the present invention, in the measurement gap adjustment method for ultrasonic flaw detection according to claim 1, when correcting the measurement gap, from the observation delay time ΔT1 of the transmission wave and the surface wave, the transmission side The distance A between the probe and the surface of the object to be measured is calculated from (ΔT1 × sonic velocity in water), and the thickness C of the object to be measured is calculated from the observation delay time ΔT2 of the surface wave and the bottom surface wave (ΔT2 If the distance A is different from a preset gap between the probe on the transmitting side and the measurement object, the gap is calculated from the calculation of the sound velocity in the measurement object). From the calculation of the transmitter / receiver probe interval Y, the distance A, and the plate thickness C (Y− (A + C) = the probe gap D on the receiving side) The probe gap D is obtained, and the probe gap D on the receiving side is If there is a difference in comparison with a preset gap between the probe on the receiving side and the object to be measured, the ultrasonic flaw detection is characterized by adjusting the gap to be the probe gap D on the receiving side This is a measurement gap adjustment method in FIG.

  Furthermore, the invention according to claim 3 of the present invention is such that a measurement object is arranged between a probe on the transmission side and a probe on the reception side, ultrasonic waves are transmitted from the probe on the transmission side, and A measurement gap adjustment device for ultrasonic flaw detection that detects internal defects of a measurement target by receiving with a probe, a flaw detector unit that performs flaw detection of a measurement target from a received wave, and a probe on a transmission side A mechanism unit that holds the probe on the transmitter side and the probe on the reception side, and moves each of them vertically, and a control unit that instructs the mechanism unit to position the probe on the transmission side and the probe on the reception side. And the flaw detector unit measures the reception timing of the transmission wave, the surface wave, and the bottom surface wave, and based on the reception timing, the control unit sets the respective probes and the measurement target that are set in advance. In ultrasonic flaw detection characterized by correcting the measurement gap with It is a measurement gap adjustment device.

  The present invention corrects the measurement gap between each probe and the measurement object set in advance from the flaw detection information of the measurement object by measuring the transmission wave, the surface wave, and the bottom wave from the measurement object. Therefore, the internal defect to be measured can be detected with the optimum measurement gap, and the internal defect can be detected with high accuracy.

  FIG. 1 is a diagram showing a configuration example of a measurement gap adjusting device in ultrasonic flaw detection according to the present invention. An example in which a steel plate is used as a measurement target will be described below. In the figure, 1 is a steel plate, 2 is an upper probe, 3 is a lower probe, 4 is a mechanism unit, 5 is a high-order computer unit, 6 is a flaw detector unit, and 7 is a control unit.

  This apparatus holds an upper computer unit 5 that transmits flaw detection information, a flaw detector unit 6 that performs flaw detection, an upper probe 2, a lower probe 3, and an upper probe 2 and a lower probe 3. The mechanism unit 4 is configured to be movable in the vertical direction, and the control unit 7 is configured to instruct the mechanism unit 4 to position the upper probe 2 and the lower probe 3. The upper probe 2 and the lower probe Internal defects of the steel plate 1 are detected between the core 3 and the child 3. A water column is formed in each gap between the steel plate 1 and the upper probe 2 and the lower probe 3 or is filled with water (submerged).

  In order to perform the flaw detection on the steel plate 1, first, the host computer unit 5 transmits flaw detection information to the flaw detector unit 6 in advance, and the control unit controls the gap between the probe and the steel plate based on flaw detection information (plate thickness, material, etc.). 7 to send. In accordance with the gap, the control unit 7 drives the mechanism unit 4 to adjust the gap to a predetermined value.

  FIG. 3 is a diagram schematically showing a gap between the initially set steel plate and the upper and lower probes. In the gap setting results, the distance between the upper probe and the lower probe is represented as Y, the gap from the upper probe to the steel plate surface is represented as X, and the gap from the lower probe to the steel plate back surface is represented as Z. Yes.

  Then, an ultrasonic transmission waveform T is transmitted from one of the upper probe 2 and the lower probe 3 to the other (hereinafter, from the upper probe 2 at the upper part of the steel plate to the lower probe 3). Shall be sent). FIG. 2 is a diagram schematically showing a waveform observed by a receiving probe. In the figure, 8 represents a transmission wave T, 9 represents a surface wave S, and 10 represents a bottom wave B. As shown in the figure, the transmission waveform T, the surface wave S reflected from the steel plate surface, and the bottom wave B reflected from the steel plate bottom surface are observed in order.

  From the observation delay time ΔT1 of the transmission wave T and the surface wave S, the distance A between the transmission probe above the steel plate and the steel plate surface can be measured from the calculation of (ΔT1 × sonic velocity in water). Further, from the observation delay time ΔT2 of the surface wave S and the bottom surface wave B, the thickness C of the steel plate can be measured from the calculation of (ΔT2 × sonic velocity in the steel plate).

  The initially set gap is corrected as follows based on the distance A to the transmission probe at the upper part of the steel plate and the steel plate surface thus obtained and the plate thickness C of the steel plate. That is, as shown in FIG. 3, when the measured gap A is different from the preset gap X of the upper probe and the steel plate, the mechanism is adjusted so that the measured gap A is obtained.

  Further, the lower probe gap D is obtained from the calculation of (Y− (A + C) = lower probe gap D) from the upper / lower probe interval Y, the measured value A, and the measured value C, and this lower probe gap is obtained. If there is a difference between D and (the preset gap Z between the lower probe and the steel plate), the mechanism is adjusted so that the lower probe gap D is obtained. By adjusting the gap between the upper and lower probes and the steel plate in this way, an optimum flaw detection waveform can be obtained, and the measurement performance can be stabilized.

  Up to this point, the explanation was given assuming that the inspection was performed at the start of the flaw detection on the target steel sheet. However, if the gap fluctuates due to fluctuations in the pass line during flaw detection on the same steel sheet, the upper and lower probes have a constant thickness. The time for changing the setting can be shortened by moving both the upper and lower probes simultaneously with a fixed interval.

  In the above description, the upper probe is used as the transmission side and the lower probe is used as the reception side. However, the same applies to the case where the lower probe is used as the transmission side and the upper probe is used as the reception side. It goes without saying that it is possible.

  In addition, by dividing the drive and transmission / reception sections of the mechanism section into a plurality of parts in the width direction and making them individually driveable, even if the material has unevenness due to elongation in the width direction of the steel sheet, A gap can be formed and flaw detection can be performed with high accuracy.

  Although the description has been made on the transmission type ultrasonic flaw detection, the measurement gap correction can be performed based on the same concept even in the one-side flaw detection using the reflected wave from the upper part or the lower part of the steel plate.

It is a figure which shows the structural example of the measurement gap adjustment apparatus in the ultrasonic flaw detection which concerns on this invention. It is a figure which shows typically the waveform observed with the probe to receive. It is a figure which shows typically the gap of the steel plate initialized and the upper and lower probe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Upper probe 3 Lower probe 4 Mechanism part 5 High-order computer part 6 Flaw detector part 7 Control part 8 Transmission wave T
9 Surface wave S
10 Bottom wave B

Claims (3)

The measurement object is placed between the probe on the transmission side and the probe on the reception side, and ultrasonic waves are transmitted from the probe on the transmission side and received by the probe on the reception side. A method for adjusting a measurement gap in ultrasonic flaw detection for flaw detection,
The measurement gap between each of the probes and the measurement object preset from the flaw detection information of the measurement object,
A measurement gap adjustment method in ultrasonic flaw detection, wherein correction is performed by measuring a transmission wave, a surface wave, and a bottom wave from the measurement object. In the method for adjusting a measurement gap in ultrasonic flaw detection according to claim 1,
In correcting the measurement gap,
From the observation delay time ΔT1 of the transmitted wave and surface wave, the distance A between the probe on the transmitting side and the surface to be measured is calculated from (ΔT1 × sound velocity in water), and the surface wave and bottom wave are observed. From the delay time ΔT2, the thickness C of the object to be measured is calculated from (ΔT2 × sound velocity in the object to be measured),
If the distance A is different from the preset gap between the probe on the transmitting side and the object to be measured, adjust the gap to be the distance A,
The probe gap D on the reception side is obtained from the calculation of (Y− (A + C) = probe gap D on the reception side) from the preset transmission / reception probe interval Y, the distance A, and the plate thickness C, If there is a difference between the probe gap D on the reception side and the preset gap between the probe on the reception side and the object to be measured, the gap becomes the probe gap D on the reception side. A method for adjusting a measurement gap in ultrasonic flaw detection, characterized in that the adjustment is carried out. The measurement object is placed between the probe on the transmission side and the probe on the reception side, and ultrasonic waves are transmitted from the probe on the transmission side and received by the probe on the reception side. A measurement gap adjusting device for ultrasonic flaw detection, which detects flaws,
A flaw detector that performs internal defect flaw detection from the received wave; and
A mechanism that holds the probe on the transmission side and the probe on the reception side and makes each moveable in the vertical direction,
A control unit for instructing the positioning of the probe on the transmission side and the probe on the reception side to the mechanism unit; and
The flaw detector unit measures the reception timing of transmission waves, surface waves and bottom waves,
The measurement gap adjusting device in ultrasonic flaw detection, wherein the control unit corrects a preset measurement gap between each of the probes and the measurement object based on the reception timing.

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