JP2008058029A - Ultrasonic analysis system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic analysis system capable of acquiring multipoint ultrasonic vibration on an inspection object having a complicated surface shape. <P>SOLUTION: The ultrasonic analysis system 1 is a system for performing ultrasonic analysis by using a rail 3 as the inspection object. The system 1 has an ultrasonic probe 5 for transmitting an ultrasonic wave for inspection to the rail 3; a laser Doppler vibrometer 7 having a laser projecting/receiving part 7a for irradiating laser light to a reception point P on the rail 3 surface, for measuring ultrasonic vibration at the reception point P; and a robot arm 19 for moving the laser projecting/receiving part 7a. A computer 17 controls the robot arm so that the laser projecting/receiving part 7a is moved along the rail 3 surface, while keeping a position relation for allowing laser light from the laser projecting/receiving part 7a to enter the rail 3 surface vertically. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic analysis system that performs ultrasonic analysis of an inspection object having a surface including a curved surface.

Conventionally, as a technology in the field of ultrasonic analysis, an ultrasonic probe is scanned in the X and Y directions using an XY stage, and the surface of the inspection object is scanned to obtain ultrasonic vibrations at multiple points on the surface. In addition, a method for obtaining a planar distribution of abnormalities inside an inspection object has been known (for example, see Non-Patent Document 1).
19th Committee of Japan Society for the Promotion of Science, “Ultrasonic Analysis”, revised edition, Nikkan Kogyo Shimbun, 1974, p268-276.

  However, in the above method, since the probe moves in a plane, it is suitable for an inspection in which a plane is scanned on the surface of the inspection object, but a surface including a curved surface cannot be scanned. Therefore, in the above method, ultrasonic analysis based on multi-point ultrasonic vibrations cannot be performed on an inspection object having a complicated surface shape.

  Therefore, an object of the present invention is to provide an ultrasonic analysis system that can acquire ultrasonic vibrations at multiple points on an inspection object having a complicated surface shape.

  An ultrasonic analysis system according to the present invention is an ultrasonic analysis system that performs ultrasonic analysis of an inspection object having a surface including a curved surface, an ultrasonic probe that transmits ultrasonic waves for inspection to the inspection object, and an inspection A laser vibrometer that irradiates a measurement spot on the surface of the object with a laser beam, a laser vibrometer that measures the vibration caused by the inspection ultrasonic waves at the measurement spot, and a robot arm that moves the laser projecting and receiving unit; A control unit that controls the robot arm to move the laser light projecting and receiving unit along the surface of the inspection object while maintaining a positional relationship in which the laser light from the laser projecting and receiving unit is perpendicularly incident on the surface of the inspection object And.

  In this ultrasonic analysis system, ultrasonic waves for inspection are incident on an inspection object from an ultrasonic probe, and the vibration of a measurement spot on the surface of the inspection object due to the ultrasonic waves for inspection is measured by a laser vibrometer. . The laser projector / receiver of this laser vibrometer is moved by driving the robot arm, so it is possible to accurately move the laser projector / receiver along a complicated trajectory by programming the operation of the robot arm in the controller. Become. Therefore, even when the surface of the inspection object includes a complicated curved surface, the laser light projecting / receiving unit is accurately moved along the surface of the inspection object, and the surface is irradiated with the laser beam perpendicularly to the measurement spot. Can be scanned in a non-contact state. In this system, since the vibration of the surface of the inspection object is measured by a laser vibrometer, the spot diameter of the laser light from the laser light projecting / receiving unit is reduced, so that each surface on the curved surface has a small curvature radius. Spot vibrations can be measured accurately. As a result, even when the inspection object has a complicated shape, ultrasonic vibrations at multiple points on the surface can be acquired.

  According to the ultrasonic analysis system of the present invention, it is possible to acquire ultrasonic vibrations at multiple points on an inspection object having a complicated surface shape.

  Hereinafter, a preferred embodiment of an ultrasonic analysis system according to the present invention will be described in detail with reference to the drawings.

  An ultrasonic analysis system 1 shown in FIG. 1 is a system for performing ultrasonic analysis using a railroad rail 3 as an inspection object and performing material evaluation such as damage evaluation of the rail 3. The ultrasonic analysis system 1 includes an ultrasonic probe 5 that transmits ultrasonic waves for inspection, and a laser Doppler vibrometer 7 that measures ultrasonic vibrations on the surface of the rail 3 due to the ultrasonic waves for inspection.

  The ultrasonic probe 5 is installed in close contact with the surface of the rail 3, generates ultrasonic waves for inspection based on signals input through the signal generator 9 and the signal amplifier 11, and enters the rail 3. Further, a laser light projecting / receiving unit 7a of the vibrometer 7 is disposed in a non-contact manner near the surface at another position of the rail 3. And the ultrasonic vibration which generate | occur | produced on the surface of the rail 3 with the said ultrasonic wave for an inspection is detected by the said laser projector / receiver part 7a. The detected ultrasonic vibration information is converted into an electrical signal, which is input from the main body 7b of the vibrometer 7 via the AD converter 15 to the computer 17 having an oscilloscope function. Displayed / recorded.

  The laser projecting / receiving unit 7a of the vibrometer 7 constitutes a laser interferometer, which projects a laser beam having a spot diameter of about 20 μm on the surface of the rail 3 in a non-contact state and receives a reflected laser beam from the surface. To do. The vibrometer 7 detects ultrasonic vibration based on the interference of the laser light projected and received by the laser projecting / receiving unit 7a. The laser light projecting / receiving unit 7a is attached to a tip 19a of a 6-axis control robot arm 19. The robot arm 19 operates according to a control program executed by the computer (control unit) 17 and controls the three-dimensional position and posture of the laser light projecting / receiving unit 7a. By such control, the laser projector / receiver 7a is three-dimensionally positioned with an accuracy of ± 0.02 mm, and the laser beam irradiation direction of the laser projector / receiver 7a is three-dimensionally adjusted to obtain a desired position and Laser light can be incident on the rail 3 from the direction.

  When the above-described control program of the computer 13 is executed in a state where inspection ultrasonic waves are transmitted from the ultrasonic probe 5, as shown in FIG. It moves on a track along the surface of the rail 3 while changing its posture so that it is always perpendicularly incident at each point on the surface of the rail 3. A large number of receiving points P (P1, P2,..., Pm,..., Pn) are set in advance on the surface of the rail 3, and the laser light projecting / receiving unit 7a scans the surface of the rail 3 while scanning the surface. Ultrasonic vibrations at reception points (measurement spots) P1, P2,..., Pm,. The interval between the reception points P is set to a length sufficiently smaller than the wavelength of the ultrasonic wave transmitted from the ultrasonic probe 5.

  Further, during the movement of the laser projector / receiver 7a, a gap of about 100 to 200 mm is maintained between the tip of the laser projector / receiver 7a and the surface of the rail 3, and the vibration at each receiving point P is measured in a non-contact state. Is done. At this time, the driving of the robot arm 19 and the vibration measurement by the laser vibrometer 7 are linked by the computer 17, and the information of the measured ultrasonic vibration waveform at each receiving point P is displayed / displayed on the computer 17 as described above. To be recorded.

  As described above, according to the ultrasonic analysis system 1, the laser light projecting / receiving unit 7a is moved by driving the robot arm. Therefore, by programming the operation of the robot arm in the computer 17, the laser projecting / receiving unit 7a is complicated. It is possible to move accurately in a simple trajectory. Therefore, even in the analysis of the railway rail 3 having a complicated curved surface, the laser light projecting / receiving unit 7a is accurately moved along the surface of the rail 3, and the laser beam is irradiated perpendicularly to each receiving point P on the surface of the rail 3. The surface can be scanned while

  The system 1 employs a laser Doppler vibrometer 7 for measuring the ultrasonic vibration on the surface of the rail 3, and a laser beam having a small spot diameter of about 20 μm is irradiated from the laser light projecting / receiving unit 7a. Is done. Therefore, for example, even on a curved surface with a small radius of curvature where a vertical probe, an oblique probe, a focal probe, or an array probe having a size of several mm to several cm cannot be installed. If the curved surface has a radius of curvature larger than the spot diameter of the laser beam or the positioning accuracy of the robot arm 19, the ultrasonic vibration of the reception point can be accurately measured by projecting and receiving the laser beam. As a result, even in the rail 3 having a complicated shape, ultrasonic vibrations at a large number of receiving points P1, P2,..., Pm,.

  Conventionally, as a method for scanning a curved surface in ultrasonic analysis, a method using a jig formed in accordance with the curved surface shape is known. However, this method limits the surface shape of an inspection object that can be analyzed. End up. On the other hand, in the system 1, it is possible to cope with various inspection objects by changing the control program of the robot arm 19 according to the surface shape of the inspection object.

  Further, in this system 1, at each of a large number of reception points P on the surface of the rail 3, waveforms due to various ultrasonic modes (for example, Rayleigh waves propagating on the surface of the rail 3), damage 3 a inside the rail 3, etc. Waveforms such as longitudinal waves and transverse waves reflected / scattered at are superposed and detected and collected by the computer 17. Therefore, a desired ultrasonic mode waveform whose sound speed and propagation distance are known can be separated and extracted from the superimposed waveform by software processing by the computer 17.

  Therefore, the ultrasonic mode related to the most effective reception mode (for example, vertical reception, oblique reception, focal reception, etc.) is classified and extracted according to the damage form and material characteristics of the inspection object to be detected. The ultrasonic analysis of the inspection object based on the reception form becomes possible. Further, since the waveforms of various ultrasonic modes can be reproduced based on the waveforms at such a large number of reception points P, the damage evaluation of the rail 3 can be performed by comprehensive judgment based on the waveforms of the various ultrasonic modes obtained. Etc. can be performed.

  Further, conventionally, it has been necessary to replace the ultrasonic probe for detecting ultrasonic vibration for each ultrasonic mode to be used for analysis. However, in the system 1, the oblique probe is used. Mode extraction of the guided wave corresponding to the method, phased array method, etc. can be reproduced by software processing, so the ultrasonic probe related to the reception of ultrasonic vibration will be used for ultrasonic analysis There is no need to replace each ultrasonic mode.

  The present invention is not limited to the embodiment described above. For example, the ultrasonic analysis system 1 can be applied not only to the analysis of the rail 3 but also to the ultrasonic analysis of a strip steel material (L-shaped steel, C-shaped steel, etc.) having a complicated shape or a pipe.

1 is a diagram showing an embodiment of an ultrasonic analysis system according to the present invention. It is sectional drawing in the receiving point vicinity of a rail.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ultrasonic analysis system, 3 ... Railway rail (inspection object), 5 ... Ultrasonic probe, 7 ... Laser vibrometer, 7a ... Laser projector / receiver, 17 ... Computer (control part), 19 ... Robot arm , P: Reception point (measurement spot).

Claims (1)

In an ultrasonic analysis system for performing ultrasonic analysis of an inspection object having a curved surface,
An ultrasonic probe for transmitting ultrasonic waves for inspection to the inspection object;
A laser vibrometer that irradiates a laser beam to a measurement spot on the surface of the inspection object, and measures a vibration due to the ultrasonic wave for inspection at the measurement spot; and
A robot arm that moves the laser light projecting and receiving unit;
The laser light projecting and receiving unit is moved along the surface of the inspection object while maintaining a positional relationship in which the laser light from the laser light projecting and receiving unit is perpendicularly incident on the surface of the inspection object. An ultrasonic analysis system comprising: a control unit that controls a robot arm.

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