JP4897420B2 - Ultrasonic flaw detector - Google Patents

Description

  The present invention relates to an ultrasonic flaw detector used for ultrasonic inspection of various structures, and more particularly to an ultrasonic flaw detector intended for welded joints such as piping of a nuclear power plant.

  In general, ultrasonic inspection of welded joints such as pipes in nuclear power plants is performed by manual flaw detection, in which a person directly scans the probe, and a track is attached to a non-test object, and the probe is automatically driven on this track. Remote-controlled automatic flaw detection is known. Especially in the case of ultrasonic inspection in an area with a high radiation dose equivalent as in a nuclear power plant, long-term inspection work is difficult in the case of manual inspection to prevent excessive human exposure. Many operations have been applied for operation, and radiation exposure reduction has been achieved, which was practically sufficient.

  In inspection of nuclear power plant piping and the like, it is obliged to inspect the welded part from two directions. That is, for example, in the case of a structure in which the first pipe and the second pipe are welded, the welded portion is ultrasonically flawed from the first pipe side, and then the welded portion is ultrasonically flawed from the second pipe side. Thus, it is necessary to inspect the same place from two directions. At this time, after installing the ultrasonic flaw detector on the first pipe side, moving the pipe around the pipe in the direction of 360 ° for flaw detection, moving the position of the ultrasonic flaw detector toward the second pipe side, Above, it moves in the direction of 360 ° around the pipe on the second pipe side to detect flaws, so it takes a long time. In particular, with the aging of nuclear power plants in recent years, the number of welded joints to be inspected has increased, and therefore the working time has become longer.

  Here, for example, there is known an ultrasonic flaw detector that inspects two oblique angle ultrasonic probes facing each other (see, for example, Patent Document 1).

Japanese Patent No. 3557553

  However, the one described in Patent Document 1 states that in the paragraph number <0011>, “in the conventional ultrasonic testing method, the ultrasonic wave is basically transmitted and received by one probe from one direction. As described in “Flaw detection”, it is different from what requires inspection from two directions such as ultrasonic inspection of welded joints such as pipes in a nuclear power plant. Therefore, considering the case where the thing of patent document 1 is applied to the ultrasonic inspection of welded joints, such as piping in a nuclear power plant, it is the same by the 1st probe in patent document 1, and a 2nd probe. When flaw detection is performed at the welded portion, if ultrasonic waves are transmitted and received simultaneously by the first probe and the second probe, the other party's ultrasonic waves are detected as interference echoes. Therefore, in order to eliminate the interference echo, it is necessary to transmit and receive ultrasonic waves alternately by the first probe and the second probe, and it takes a long time for the flaw detection.

  An object of the present invention is to provide an ultrasonic flaw detection apparatus that can eliminate the influence of disturbing echoes and that can shorten the time required for flaw detection.

(1) In order to achieve the above object, the present invention provides an oblique ultrasonic probe that transmits and receives ultrasonic waves, and the oblique ultrasonic probe that passes along the surface of the object to be inspected. The first driving means that moves in a direction parallel to the trajectory provided on the head, the second driving means that moves in the orthogonal direction, and the control means that controls the first and second driving means. In the flaw detection apparatus, the oblique angle ultrasonic probe includes a first ultrasonic probe and a second ultrasonic probe, and an ultrasonic wave emitted from the first ultrasonic probe. The direction of the sound wave and the direction of the ultrasonic wave emitted from the second ultrasonic probe face each other, and the first ultrasonic probe and the second ultrasonic probe are driven. a flaw range of the first ultrasonic probe when moving in a direction perpendicular to the track provided on the inspection portion by means, before The first ultrasonic probe and the second ultrasonic probe are held by the drive means so that the flaw detection range of the second ultrasonic probe is different, and the first drive means The first position detecting means for detecting the position on the trajectory and the second driving means include the first ultrasonic probe and the holding portion for the second ultrasonic probe. A second position detecting means for detecting the position of the first driving means and the second driving means are capable of adjusting the positions of the first and second ultrasonic probes with respect to a direction orthogonal to the trajectory; 1st and 2nd adjustment part fixable with respect to the said 2nd drive means is provided, It orthogonally crosses with respect to the said track | orbit of the said 1st ultrasonic probe and the said 2nd ultrasonic probe distance D direction, the refraction angle θ of the probe, the thickness T of the non-inspected, der those to satisfy D = 2T · tan .theta .
With such a configuration, the influence of the interference echo can be eliminated and the time required for flaw detection can be shortened.

( 2 ) In the above (1), preferably, the first ultrasonic probe and the second ultrasonic probe are each provided with a water absorbing material for wiping the contact medium.

  According to the present invention, the influence of disturbing echoes can be eliminated and the time required for flaw detection can be shortened.

Hereinafter, the configuration and operation of an ultrasonic flaw detector according to an embodiment of the present invention will be described with reference to FIGS.
First, the overall configuration of the ultrasonic flaw detector according to the present embodiment will be described with reference to FIGS. 1 and 2.
FIG. 1 is a partial cross-sectional plan view showing the overall configuration of an ultrasonic flaw detector according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional side view showing the overall configuration of the ultrasonic flaw detector according to one embodiment of the present invention.

  The 1st piping 3A and 2nd piping 3B which are to-be-inspected bodies are connected by the welding part 2 which is to-be-inspected part. The central axes of the first pipe 3A and the second pipe 3B extend in the Y-axis direction in the figure. A track 1 is attached to the outer periphery of the first pipe 3A so as to make one turn around the circumference. As shown in FIG. 1, a plurality of screw holes 4 are provided in the track 1, and screws 5 are inserted into the respective screw holes 4 as shown in FIG. 2. Then, as shown in FIG. 2, the tip of the screw 5 is abutted against the outer periphery of the first pipe 3A, and the distance between the inner periphery of the track 1 and the outer periphery of the first pipe 3A is constant. The screw 5 is screwed into the screw hole 4.

  A circumferential movement device 6 is attached to the track 1 so as to be movable in the circumferential direction of the first pipe 3A. As shown in FIG. 2, the circumferential movement device 6 is supported by the circumferential movement device support rollers 10 and 11 rolling along the end surface of the track 1, and is supported by the circumferential movement device driving pinion 8 and the rack 12. Driven in the circumferential direction. The circumferential movement device driving pinion 8 is driven by a circumferential movement motor 7. The circumferential position detection encoder 9 is rotated by the motor 7 and outputs a circumferential position signal.

  An arm 13, a ball screw 14, and a ball screw moving motor 15 are attached to the circumferential direction moving device 6. A probe moving unit 18 is attached to the arm 13, and the probe moving unit 18 moves in the axial direction of the pipes 3A and 3B by the rotation of the ball screw 14.

  Two probe holders 19A and 19B are attached to the probe support 18 via springs 20A and 20B, respectively. The two probe holders 19A and 19B are provided with oblique-angle ultrasonic probes 21A and 21B, respectively. The probe support portion position detection encoder 16 attached to the ball screw drive motor 15 outputs the positions of the oblique ultrasonic probes 21A and 21B.

  Accordingly, the circumferential direction moving motor 7 allows the ultrasonic probes 21A and 21B to move 360 ° in the circumferential direction on the outer circumferences of the pipes 3A and 3B. Further, the ball probe motor 15 allows the ultrasonic probes 21A and 21B to reciprocate a predetermined distance in the axial direction (Y-axis direction) of the pipes 3A and 3B.

  Further, a probe holder position adjusting unit 17A for adjusting the position of the probe holder 19A with respect to the longitudinal direction (Y-axis direction) of the arm 13 is provided. In addition, the probe holder position adjusting unit 17A is fixed to the probe support unit 18 by screws 24A. Similarly, the probe holder 19B includes a probe holder position adjusting unit 17B.

  Here, the oblique ultrasonic probes 21A and 21B are installed such that the ultrasonic waves 22A and 22B transmitted from the oblique ultrasonic probes 21A and 21B face each other. That is, as shown in FIG. 2, when viewed from the X-axis direction, an ultrasonic wave 22A transmitted from the oblique ultrasonic probe 21A and an ultrasonic wave 22B transmitted from the oblique ultrasonic probe 21A are provided. They are in opposite directions. Further, as shown in FIG. 1, the oblique ultrasonic probe 21A and the oblique ultrasonic probe 21B are arranged apart from each other in the X-axis direction, and the distance D in the Y-axis direction. Are placed apart. The distance D will be described later with reference to FIGS. With such an arrangement, the ultrasonic flaw detection ranges of the two ultrasonic probes 21A and 21B are different. Since the ultrasonic flaw detection ranges are different, the ultrasonic waves transmitted from the two oblique angle ultrasonic probes 21A and 21B do not interfere with each other, and therefore the influence of the disturbing echo can be reduced.

  Further, water-absorbing materials 23A and 23B are attached in front of the probe holders 19A and 19B, respectively. Therefore, each time the probe holders 19A and 19B move, the water absorbing materials 23A and 23B can wipe off the contact medium excessively applied in the flaw detection area, thereby preventing the appearance of reflected echoes from the contact medium. As the contact medium, water, glycerin, or the like is used. If the contact medium is not uniformly distributed on the surface of the non-inspection object, the result of the flaw detection includes a reflection echo from the defect and a reflection echo from the contact medium, which makes it difficult to specify the defect. In the present embodiment, materials having good water absorption such as sponge are used as the water absorbing materials 23A and 23B. Since the contact medium is uniformly distributed on the surface of the non-inspection object by wiping the contact medium with the water absorbing materials 23A and 23B, reflection echoes from the non-uniform contact medium can be reduced.

Next, the movement distance in the Y-axis direction of the two probes in the ultrasonic flaw detector according to the present embodiment will be described with reference to FIGS.
3-6 is a side view which shows the principal part structure of the ultrasonic flaw detector by one Embodiment of this invention.

  As shown in FIGS. 3 and 4, in an ultrasonic flaw detection test such as a pipe in a nuclear power plant, the flaw detection range A including the welded portion 2 is flawed from the first pipe 3A side as shown in FIG. (This is referred to as “+ Y direction flaw detection”), and as shown in FIG. 4, it is necessary to perform flaw detection from the second pipe 3B side (this is referred to as “−Y direction flaw detection”). is there.

In order to satisfy the flaw detection range A by flaw detection in the + Y direction, it is necessary to move the probe 21B from the position Y1 to the position Y1 ′ as shown in FIG. In order to satisfy the flaw detection range A by flaw detection in the -Y direction, it is necessary to move the probe 21A from the position Y2 to the position Y2 'as shown in FIG. Accordingly, as shown in FIG. 5, the probe interval D when the flaws are detected simultaneously by the two probes 21A and 21B in two directions as in this embodiment is shown in FIG. If the angle is θ and the thickness of the non-specimen is T,

D = 2T · tan θ (1)

It becomes.

  As described above, in the present embodiment, the probe holder position adjusting portions 17A and 17B are provided. Therefore, by changing the position fixed to the probe support portion 18 by the screw 24A, the equation (1) is used. It can be adjusted to the required distance D between the probes.

Here, a specific example will be described with reference to FIG. When the flaw detection area including the welded joint is A = 49.0 mm, the plate thickness is T = 29.6 mm, and the incident angle of the ultrasonic wave transmitted from the probes 21A and 21B is θ = 42.3 °, the minimum drive range H is

H = A + D
= A + 2T × tan (θ)

Therefore, H = 102.9≈103 mm.

The distance D between the probes is
D = 2T × tan (θ)
Therefore, D = 53.9≈54 mm.

  When the distance D between the probes is fixed to 54 mm and the probe 21B is scanned from the weld joint center to the front by hb = A / 2 = 24.5 mm and backward by ha = H−hb = 78.5 mm, other probes are scanned. Similarly, the touch element 21A can also detect the flaw detection range A. In addition, by moving the probes 21A and 21B about 360 ° on the outer periphery of the pipe by the circumferential movement device 6, the entire circumference range of 360 ° can be detected for the flaw detection range A.

  Therefore, compared with the case of one conventional probe, the work time can be shortened by more than twice based on the probe replacement work and the like.

  Note that the distance between the two probes 21A and 21B may be wider or narrower than the distance D between the probes described above. However, in this case, the driving range of the probe is somewhat wider than the driving range H described above, and thus the working time is somewhat longer. Nevertheless, compared with the case of one conventional probe, The time can be shortened.

Next, the system configuration of the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 7 is a block diagram showing the system configuration of the ultrasonic flaw detector according to one embodiment of the present invention.

  This system includes a recording unit 52 for recording the position coordinates of the pipes 3A and 3B obtained based on output signals from the encoder 9 for detecting the position of the circumferential moving device and the encoder 16 for detecting the position of the probe support unit. A display unit 50 for displaying the result and an input unit 51 for inputting the inspection range and the like are provided. Further, this system detects pulse positions of pulser receivers 53A and 53B that transmit ultrasonic waves to the ultrasonic probes 21A and 21B and receive ultrasonic waves, A / D boards 54A and 54B, and circumferential direction moving device positions. Counter boards 55 and 56 for taking in output signals from the encoder 9 and the probe support portion position detection encoder 16.

  The calculation unit 60 is a computer, and controls the circumferential direction moving device driving motor 7 and the ball screw driving motor 16. Output signals from the circumferential movement device position detection encoder 9 and the probe support portion position detection encoder 17 are input to the calculation unit 60 via the counter boards 55 and 56. A reception signal obtained by transmitting / receiving ultrasonic waves from / to the pipe from the ultrasonic probe is input to the calculation unit 60 via the pulser receivers 53A and 53B and the A / D boards 54A and 54B. Further, the arithmetic unit 60 performs image processing on the obtained A scope information to obtain C scope image data. The C scope image data will be described later with reference to FIG.

Next, display examples obtained using the ultrasonic flaw detector according to the present embodiment will be described with reference to FIGS.
FIG. 8 is a model diagram of piping for explaining a display example obtained by using the ultrasonic flaw detector according to one embodiment of the present invention. In FIG. 8, the same reference numerals as those in FIGS. 2 to 6 denote the same parts. FIG. 9 is an explanatory diagram of an A scope which is one of display examples obtained using the ultrasonic flaw detector according to one embodiment of the present invention. FIG. 10 is an explanatory diagram of a C scope which is one of display examples obtained using the ultrasonic flaw detector according to one embodiment of the present invention.

  As shown in FIG. 8, it is assumed that there is a defect D in the vicinity of the weld 2 and this defect is detected by ultrasonic waves 22A and 22B emitted from the ultrasonic probes 21A and 21B.

  FIG. 9 shows an image of the A scope. In the A scope, the horizontal axis represents time and the vertical axis represents echo height. FIG. 9A shows an A scope for the ultrasonic probe 21A, and FIG. 9B shows an A scope for the ultrasonic probe 21B. What is displayed near time 0 is an echo of the emitted ultrasonic wave. Defect echoes, shape echoes, etc. are displayed at positions farther than time zero. Here, a defect echo is displayed. Since the distance to the defect D is closer to the ultrasonic probe 21A, the intensity of the defect echo is greater in the case shown in FIG. 9B than that shown in FIG. 9A.

  FIG. 10 shows an image of the C scope. In the coordinate system shown in FIG. 9, the C scope image information is image information whose luminance is modulated in accordance with the amplitude of the A scope and the position on the object to be inspected and the ultrasonic propagation time are represented by rectangular coordinates (xy plane). The C scope image information is expressed in the coordinate format of a plan view (xy plane) obtained by viewing the flaw detection result from above the inspection object. FIG. 10A shows a C scope for the ultrasonic probe 21A, and FIG. 10B shows a C scope for the ultrasonic probe 21B.

  In FIGS. 10A and 10B, line C is a line indicating the center position of welded portion 2. The shape echo SE from the position of the outer contour of the weld 2 is displayed at a substantially constant position with respect to the center line C. In addition, a defect eco DE for the defect D is displayed at a predetermined distance from the center line. The position of the defect can be detected from the relationship between the shape echo SE and the defect echo DE.

As described above, according to this embodiment, the influence of disturbing echoes can be eliminated and the time required for flaw detection can be shortened.

It is a top view of the partial cross section which shows the whole structure of the ultrasonic flaw detector by one Embodiment of this invention. It is a side view of the partial cross section which shows the whole structure of the ultrasonic flaw detector by one Embodiment of this invention. It is a side view which shows the principal part structure of the ultrasonic flaw detector by one Embodiment of this invention. It is a side view which shows the principal part structure of the ultrasonic flaw detector by one Embodiment of this invention. It is a side view which shows the principal part structure of the ultrasonic flaw detector by one Embodiment of this invention. It is a side view which shows the principal part structure of the ultrasonic flaw detector by one Embodiment of this invention. It is a block diagram which shows the system configuration | structure of the ultrasonic flaw detector by one Embodiment of this invention. It is a piping model figure for demonstrating the example of a display obtained using the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of A scope which is one of the example of a display obtained using the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of C scope which is one of the display examples obtained using the ultrasonic flaw detector by one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Track 2 ... Welded part 3 ... Pipe 4 ... Screw hole 5 ... Screw 6 ... Circumferential movement apparatus 7 ... Circumferential movement motor 8 ... Circumferential movement apparatus drive pinion 9 ... Circumferential position detection encoders 10, 11 ... Roller 12 for supporting the circumferential direction moving device ... Rack 13 ... Arm 14 ... Ball screw 15 ... Motor 16 for driving the ball screw ... Encoder 17 for detecting the probe support part ... Probe holder adjusting part 18 ... Probe support Parts 19a, 19B ... Probe holder 20 ... Springs 21A, 21B ... Oblique ultrasonic probes 22A, 22B ... Ultrasound 23A, 23B ... Water absorbing material 24A ... Screw 50 ... Display part 51 ... Input part 52 ... Recording part 60 ... Calculation unit

Claims (2)

An oblique ultrasonic probe for transmitting and receiving ultrasonic waves;
First drive means for moving the oblique ultrasonic probe along the surface of the object to be inspected in a direction parallel to the trajectory provided in the inspected part, and second drive for moving in the orthogonal direction Means,
An ultrasonic flaw detector having control means for controlling the first and second drive means,
The oblique angle ultrasonic probe comprises a first ultrasonic probe and a second ultrasonic probe,
The direction of the ultrasonic wave emitted from the first ultrasonic probe and the direction of the ultrasonic wave emitted from the second ultrasonic probe are opposed to each other, and the first ultrasonic probe and A flaw detection range of the first ultrasonic probe when the second ultrasonic probe is moved in a direction orthogonal to a trajectory provided in the inspected portion by the driving means; and the second The first ultrasonic probe and the second ultrasonic probe are held by the second driving means so that the flaw detection range of the ultrasonic probe is different from each other.
The first driving means includes a first position detecting means for detecting a position on the trajectory, and the second driving means includes the first ultrasonic probe and the second ultrasonic wave. Second position detection means for detecting the position of the holding portion of the probe ;
The second driving means can adjust the positions of the first and second ultrasonic probes with respect to a direction orthogonal to the trajectory, and can be fixed to the second driving means. 1 and a second adjustment unit,
The distance D in the direction orthogonal to the trajectory of the first ultrasonic probe and the second ultrasonic probe is determined by the refraction angle θ of the probe and the thickness T of the non-inspection object. On the other hand, an ultrasonic flaw detector characterized by satisfying D = 2T · tan θ . The ultrasonic flaw detector according to claim 1,
The ultrasonic inspection apparatus, wherein the first ultrasonic probe and the second ultrasonic probe include a water absorbing material that wipes off a contact medium.

Images