JP2007205959A - Probe unit for ultrasonic flaw detector, and method of estimating crack depth by ultrasonic flaw detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a probe unit for an ultrasonic flaw detector which inspects satisfactorily a defective part, without using a "single reflection method", even when the defective part to be subjected to ultrasonic flaw detection exists as a surface crack of an inspected object and even when an obstacle exists on a face, and also to provide a method of estimating a crack depth by an ultrasonic flaw detection method. <P>SOLUTION: The probe unit 1 for the ultrasonic flaw detector is provided with a transmitting probe 1a and a receiving probe 1b, and the transmitting probe 1a is arranged in the probe unit 1 to incline a sound axis 2a to a receiving probe 1b side. This method of estimating the crack depth by the ultrasonic flaw detection method uses the probe unit 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a probe unit for an ultrasonic flaw detection apparatus and a crack depth estimation method using an ultrasonic flaw detection method.

  Conventionally, an ultrasonic flaw detection method is known as a method for inspecting the inside of an inspection object without destroying the inspection object. The ultrasonic flaw detection method is a method for inspecting the inside of an inspection object by checking a reflected wave on a monitor while bringing a probe for transmitting and receiving ultrasonic waves into close contact with the surface of the inspection object and moving it. is there.

  FIG. 3 shows a state in which the inspection object 10 is inspected by this ultrasonic flaw detection method. In this figure, 11 is a probe for an ultrasonic flaw detector, 13 is a defective portion existing in the inspection object 10, 14 is an ultrasonic wave transmitted from the probe 11, and θ Respectively indicate the incident angles of the ultrasonic waves 14.

  In this ultrasonic flaw detection method, first, the probe 11 is brought into contact with the lower surface of the object 10 to be inspected, and the ultrasonic wave 14 is transmitted from the probe 11 at a predetermined incident angle θ. Next, the reflected wave of the ultrasonic wave 14 is received by the probe 11, and the distance W from the probe 11 to the defect portion 13 is determined based on the time required from the transmission of the ultrasonic wave to the reception.

  Then, a calculation is performed based on the distance W, the distance y from the position (reference position) R serving as a measurement reference to the probe 11, and the values of the incident angle θ of the ultrasonic wave 14, thereby calculating the reference position. A distance X from R to the defective portion 13 and a depth D of the defective portion 13 are obtained. In this way, the position of the defective portion 13 is specified.

JP 2004-333387 A

  By the way, in such an ultrasonic flaw detection method, as shown in FIG. 4, when the defect portion 13 exists as a surface crack of the inspection object 10 and the obstacle 15 exists on the surface. When the incident angle θ of the ultrasonic wave 14 transmitted from the probe 11 is small, the ultrasonic wave 14 does not hit the defect part 13 and a reflected wave from the defect part 13 cannot be obtained, so that the flaw detection inspection cannot be performed. . Therefore, in such a case, it is necessary to increase the incident angle θ of the ultrasonic wave 14 (decrease the incident angle θ), transmit the ultrasonic wave, and perform a flaw detection inspection.

  However, when ultrasonic flaw detection is performed by increasing the incident angle θ, a surface wave 17 is generated on the surface of the inspection object 10 as shown in FIG. It interferes with the reflected wave from the defective part 13. As a result, since the reflected wave from the defect portion 13 is weakened, the reflected wave from the defect portion 13 cannot be suitably received by the probe 11, and there is a problem that an accurate flaw detection inspection cannot be performed.

  In such a case, the inspection method using the “single reflection method”, that is, as shown in FIG. 6A, the transmitted ultrasonic wave 14 is opposite to the surface on which the probe 11 is contacted. A method of performing ultrasonic flaw detection by reflecting on the side surface is also conceivable. However, as shown in FIG. 6B, this single reflection method cannot be suitably implemented because the ultrasonic waves are scattered when the surface to which the ultrasonic waves are reflected is not smooth. There is.

  The present invention has been made to solve such a problem in the conventional ultrasonic flaw detection method, in which the defect exists as a surface crack of the object to be inspected, and an obstacle exists on the surface. Even if it is a case, the probe unit for an ultrasonic flaw detector capable of suitably inspecting the defect without using the “single reflection method”, and the crack depth by the ultrasonic flaw detection method The purpose is to provide an estimation method.

  As a means therefor, a probe unit for an ultrasonic flaw detector according to the present invention comprises a transmitting probe and a receiving probe, and the transmitting probe is there. An oblique angle probe having an incident angle of ultrasonic waves transmitted from 78 ° to 88 °, the sound axis of which is inclined to the receiving probe side and disposed in the probe unit. It is characterized by being.

  In addition, the method for estimating the crack depth by the ultrasonic flaw detection method according to the present invention is a simulation test in which a probe unit including a transmitting probe and a receiving probe is artificially provided with a crack. After contacting the piece, an ultrasonic wave is transmitted from the transmitting probe to the simulation test piece at an incident angle of 78 ° to 88 °, and then the reflected wave of the ultrasonic wave is transmitted to the receiving probe. The intensity standard value is obtained from the intensity of the received reflected wave, and after that, the probe unit is brought into contact with the object to be inspected, and then incident on the object to be inspected at 78 ° to 88 °. After transmitting an ultrasonic wave from the transmitting probe at a corner, the reflected wave of the ultrasonic wave is received by the receiving probe, and the intensity of the received reflected wave is obtained with the obtained intensity standard value and By comparing and contrasting, the depth of the crack existing in the object to be inspected is estimated.

  In the probe unit according to the present invention and the crack depth estimation method based on the ultrasonic flaw detection method, the sound axis of the receiving probe is set to be 10 ° or more with the sound axis of the transmitting probe. When arranged in the probe unit so as to intersect within a range of 30 ° or less, the receiving efficiency of the receiving probe can be further improved.

  According to the probe unit for an ultrasonic flaw detector according to the present invention and the crack depth estimation method by the ultrasonic flaw detection method, the surface crack of the object to be inspected exists and on the surface. Even if there is an obstacle, the crack depth can be suitably inspected without using the “single reflection method”.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 shows a state in which the probe unit 1 according to this embodiment is viewed from directly above. The probe unit 1 includes a transmitting probe 1a for transmitting ultrasonic waves and a receiving probe 1b for receiving reflected waves of the transmitted ultrasonic waves. In this figure, 2a indicates the sound axis of the transmitting probe, and 2b indicates the sound axis of the receiving probe.

  As shown in the figure, in the probe unit 1, the sound axis 2a of the transmitting probe 1a is inclined toward the receiving probe 1b in order to increase the receiving efficiency of the receiving probe 1b. Has been placed. In this case, the crossing angle α between the sound axis 2a of the transmitting probe 1a and the sound axis 2b of the receiving probe 1b should be 10 ° to 30 ° (20 ° ± 10 °). Is preferred. This is because setting the crossing angle α within this range is based on an empirical rule that reception efficiency is the best.

  And the probe 1a for transmission with which the probe unit 1 is provided is an oblique probe which transmits an ultrasonic wave diagonally forward, Comprising: Compared with the general probe which is 78 degrees or more and 88 degrees or less. Ultrasound is transmitted at a shallow incident angle.

  In addition, if the incident angle of the transmitted ultrasonic wave is so shallow, a surface wave is generated, and the reflected wave from the defect portion is weakened due to interference with the reflected wave, and it is considered that an accurate flaw detection inspection cannot be performed, In the probe unit 1 according to the present embodiment, the transmitting probe 1a and the receiving probe 1b are separately arranged, and the sound axis 2a of the transmitting probe 1a is used as the receiving probe. Since it is arranged to be inclined toward the contact 1b and the reception efficiency can be improved, even if such interference occurs and the reflected wave from the defective portion is weakened, the flaw detection inspection can be suitably performed.

  Next, a method for estimating the crack depth by the ultrasonic flaw detection method using the probe unit 1 will be described. FIG. 2 shows a state in which the probe unit 1 is brought into contact with the lower surface of the inspection object 10 and ultrasonic flaw detection is performed from the side. In this figure, 3 is a crack generated from the lower surface of the inspection object 10, 4 is an ultrasonic wave transmitted from the transmitting probe 1a, 5 is an obstacle, and θ is an ultrasonic wave 4. The incident angle, and the hatched portion in the figure indicates the ultrasonic beam bundle that has spread from the ultrasonic wave 4.

  First, as shown in the drawing, when the probe unit 1 is brought into contact with the inspection object 10, the ultrasonic wave 4 is transmitted to the inspection object 10. In addition, since the ultrasonic wave 4 transmitted here is transmitted from the probe 1a for transmission, it is transmitted at an incident angle of 78 ° or more and 88 ° or less.

  Next, the reflected wave that returns upon hitting the crack 3 is received by the receiving probe 1b (in FIG. 2, the receiving probe 1b is directly behind the transmitting probe 1a. Not shown). Then, by comparing and comparing the intensity of the reflected wave received by the receiving probe 1b with an intensity standard value obtained in advance (details will be described later), the depth of the crack existing in the object to be inspected. Guess.

  As shown in FIG. 2, since the crack 3 does not exist on the center line of the ultrasonic beam bundle, it is recognized that the intensity of the reflected wave that hits the crack 3 is very weak. In the probe unit 1 according to the embodiment, the transmitting probe 1a and the receiving probe 1b are separately arranged, and the sound axis 2a of the transmitting probe 1a is set to be a receiving probe. Since it is arranged so as to be inclined toward the 1b side so that the reception efficiency can be improved, even such a weak reflected wave can be received accurately.

  Next, a method for obtaining the above-described intensity standard value will be described. First, mock specimens with artificial cracks of various depths are prepared. Here, the crack provided in each simulated test piece is preferably the same as the crack that can actually occur in the object to be inspected in order to reduce the error during the subsequent comparison. That is, it is preferable to provide a crack that is not caused by a slit-like clean crack provided by an electric discharge machine, but is actually broken by applying force and caused by this breakage.

  Next, the probe unit 1 is brought into contact with the surface of each simulation test piece, and the ultrasonic wave 4 is transmitted from the probe 1a for transmission. Then, the reflected wave from the artificially provided crack is received by the receiving probe 1b, and the intensity of the received reflected wave is recorded for each simulation test piece. In this way, standard strength values for cracks of various depths are obtained.

  When obtaining the strength standard value, it is too fine. For example, obtaining the strength standard value for every crack depth of 0.1 mm requires a lot of labor. A correlation curve may be created from the relationship of the crack depth, and a detailed strength standard value may be obtained therefrom.

  Moreover, it is not always necessary to prepare the strength standard value by preparing a mock test piece. For example, if a reliable standard value is obtained from actual inspection data performed in the past, it may be used, or may be obtained by simulation using a computer.

  In the above embodiment, the transmitting probe 1a and the receiving probe 1b are arranged in close contact with each other in the probe unit 1. However, they need to be arranged in close contact with each other. If the respective distances are constant, they may be arranged at a predetermined interval, or they may be shifted back and forth.

  As described above, according to the probe unit for an ultrasonic flaw detector according to the present invention and the crack depth estimation method using the ultrasonic flaw detection method, the ultrasonic wave transmitted from the transmitter is transmitted. When the incident angle of the sound wave is a shallow incident angle of 78 ° or more and 88 ° or less, the transmitting probe and the receiving probe are arranged separately, and the sound axis of the transmitting probe is Since it is arranged to be inclined to the receiving probe side so as to improve the receiving efficiency, the surface crack of the object to be inspected exists and the obstacle exists on the surface. However, the crack depth can be suitably inspected without using the “single reflection method”.

The figure which showed the probe unit 1 which concerns on this invention. The figure which showed a mode that ultrasonic testing was implemented using the probe unit 1 which concerns on this invention. FIG. 1 is an explanatory diagram of a conventional ultrasonic flaw detection method. FIG. 2 is an explanatory diagram of a conventional ultrasonic flaw detection method. FIG. 3 is an explanatory diagram of a conventional ultrasonic flaw detection method. FIG. 4 is an explanatory diagram of a conventional ultrasonic flaw detection method.

Explanation of symbols

1: Probe unit,
1a: outgoing probe,
1b: reception probe,
2a: sound axis of the probe 1a for transmission,
2b: sound axis of the receiving probe 1b,
3: Crack,
4: Ultrasound,
10: Inspected object,
11: Probe,
13: defective part,
14: Ultrasound,
15: Obstacle,
17: surface wave,
α: intersection angle between the sound axis 2a of the transmitting probe 1a and the sound axis 2b of the receiving probe 1b,
θ: Angle of incidence of ultrasonic wave

Claims (5)

A probe unit for an ultrasonic flaw detector comprising a probe for transmission and a probe for reception,
The transmitting probe is an oblique probe in which an incident angle of an ultrasonic wave transmitted therefrom is 78 ° or more and 88 ° or less, and its sound axis is inclined to the receiving probe side. A probe unit for an ultrasonic flaw detector, which is disposed in the probe unit.   The receiving probe is arranged in the probe unit so that the sound axis thereof intersects the sound axis of the transmitting probe within a range of 10 ° to 30 °. The probe unit for an ultrasonic flaw detector according to claim 1, wherein the probe unit is an ultrasonic flaw detector.   After a probe unit having a transmitting probe and a receiving probe is brought into contact with an inspection object, the transmitting probe is incident on the inspection object at an incident angle of 78 ° to 88 °. After transmitting the ultrasonic wave more, the reflected wave of the ultrasonic wave is received by the receiving probe, and by comparing and contrasting the intensity of the received reflected wave with the intensity standard value obtained in advance, A method for estimating crack depth by an ultrasonic flaw detection method, wherein the depth of a crack existing in an object to be inspected is estimated.   In the probe unit, the transmitting probe and the receiving probe are arranged so that their sound axes intersect within a range of 10 ° to 30 °. A method for estimating crack depth by the ultrasonic flaw detection method according to claim 3.   After the probe unit is brought into contact with the artificial test piece provided with an artificial crack, ultrasonic waves are transmitted from the transmitting probe at an incident angle of 78 ° or more and 88 ° or less to the simulation test piece. The ultrasonic flaw detection according to claim 3, wherein the reflected wave of the ultrasonic wave is received by the receiving probe, and the intensity standard value is obtained from the intensity of the received reflected wave. Method for estimating crack depth by the method.

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