CN-121978019-A - Laser ultrasonic scanning system for detecting basin-type insulator

CN121978019ACN 121978019 ACN121978019 ACN 121978019ACN-121978019-A

Abstract

The invention discloses a laser ultrasonic scanning system for detecting a basin-type insulator, which comprises a mechanical arm, a clamping mechanism, a laser excitation module, a laser ultrasonic receiving module and a control and data processing module, wherein the clamping mechanism is arranged at the tail end of the mechanical arm and is used for clamping and positioning the insulator and matching with the mechanical arm to realize three-dimensional posture adjustment and rotation around the axis of the mechanical arm. The control and data processing module processes the echo signals, adopts a synthetic aperture delay superposition imaging method to focus and reconstruct the circumferential scanning data to obtain B scanning images with corresponding sections, and obtains a plurality of B scanning images at multiple axial positions, and then carries out projection convergence by selecting relevant depth ranges of defects and splicing according to the axial direction to form C scanning images taking the circumferential positions and the axial positions as coordinates so as to realize visual characterization of the expansion distribution of the defects. Based on the B scanning image and the C scanning image, identifying an abnormal reflection area of the defect, and combining echo characteristics to realize defect positioning, quantitative evaluation and report output.

Inventors

XIA HUI
CHEN YUN
Ye Chenxu
HE JIN
LI ZHEYUAN
ZHAO SIYUAN
LI DEGE
ZHANG CHAO

Assignees

中国科学院电工研究所
中国电力科学研究院有限公司
国网天津市电力公司

Dates

Publication Date: 20260505
Application Date: 20260309

Claims (10)

1. A laser ultrasonic scanning system for detecting a basin-type insulator is characterized by comprising a mechanical arm, a clamping mechanism, a laser excitation module, a laser ultrasonic receiving module and a control and data processing module, wherein the clamping mechanism is arranged at the tail end of the mechanical arm and used for clamping and positioning the basin-type insulator, the laser excitation module is used for non-contact excitation of ultrasonic waves on the surface of the insulator and used for receiving ultrasonic echo signals on the surface of the insulator, and the control and data processing module is respectively and electrically connected with the mechanical arm, the laser excitation module and the laser ultrasonic receiving module and used for controlling the mechanical arm to realize three-dimensional posture adjustment of the basin-type insulator and rotation around the axis of the mechanical arm, controlling triggering and parameter setting of the laser excitation module, controlling synchronous acquisition of the laser ultrasonic receiving module and processing and imaging the acquired ultrasonic signals so as to form a circumferential scanning path on the surface of the insulator.
2. The laser ultrasonic scanning system according to claim 1, wherein the joint structure of the mechanical arm comprises a base rotary joint for realizing horizontal rotation of the mechanical arm relative to the mounting base, a lower arm pitching joint arranged between the base and the lower arm and used for driving the lower arm to do pitching motion around a horizontal axis, an upper arm pitching joint arranged between the lower arm and the upper arm and used for performing pitching adjustment on the posture of the upper arm, and a wrist multi-degree-of-freedom rotary joint arranged at the tail end of the upper arm and used for realizing fine adjustment of the end effector in rolling, pitching and yawing directions.
3. The laser ultrasonic scanning system of claim 2, wherein the mechanical arm has a rotational degree of freedom along the axis of the fixture, so that the insulator to be tested can realize 0-360 ° continuous or step-wise rotation around the axis of the mechanical arm, and has pitching and yaw degrees of freedom to adapt to different installation postures and space-limited conditions.
4. The laser ultrasonic scanning system according to claim 1, wherein the clamping mechanism comprises a clamping base rigidly connected with the wrist of the mechanical arm, three clamping jaws uniformly distributed along the circumferential direction, flexible gaskets arranged on the inner surfaces of the clamping jaws, a locking mechanism used for self-locking the positions of the clamping jaws after clamping, and a clamp axis calibration structure used for enabling the clamp axis to coincide with the geometric central axis of the basin-type insulator.
5. The laser ultrasonic scanning system according to claim 4, wherein the clamping jaw is used for clamping the outer edge of the metal flange or the basin of the insulator to realize the self-adaptive clamping of basin-shaped insulators with different specifications, and the flexible gasket is made of rubber or polyurethane elastic materials.
6. The laser ultrasound scanning system according to claim 1, wherein the laser excitation module comprises a pulsed laser and a laser induced acoustic enhancement medium disposed in the optical path of the laser, the laser induced acoustic enhancement medium being coated on a lens or an intermediate carrier in the optical path of the laser.
7. The laser ultrasound scanning system according to claim 6, wherein the laser induced acoustic enhancement medium is an MXene based titanium carbide two-dimensional layered material, preferably an MXene/PDMS composite enhancement medium loaded with gold nanoparticles.
8. The laser ultrasonic scanning system according to claim 1, wherein the laser ultrasonic receiving module comprises a laser doppler vibrometer and a high-speed data acquisition card, the receiving light spot of the receiving module is arranged near the excitation point or in a region with a preset distance from the excitation point, and a preset included angle is formed between the receiving light beam and the surface normal of the insulator by adjusting the gesture of the mechanical arm so as to optimize signal acquisition.
9. The laser ultrasonic scanning system according to claim 1, wherein the control and data processing module comprises a motion control unit for controlling the mechanical arm to realize rotation around the axis and posture adjustment of the insulator, a laser control unit for triggering control and parameter setting of the pulse laser, a signal processing unit for denoising, filtering, envelope extraction and time-frequency analysis of ultrasonic signals, and an imaging and flaw judgment unit for focusing and reconstructing echo data by adopting a circular synthetic aperture delay-and-overlap imaging method to form an ultrasonic tomography image in the insulator and at the interface thereof and identify flaws.
10. The laser ultrasonic scanning system according to any one of claims 1 to 9, wherein the control and data processing module processes echo signals, adopts a synthetic aperture delay superposition imaging method to focus and reconstruct annular scanning data to obtain B scanning images with corresponding sections, acquires a plurality of B scanning images in a multi-axial direction, performs projection convergence by selecting a relevant depth range of a defect and performs axial stitching to form a C scanning image with the annular position-axial position as a coordinate, realizes visual characterization of defect unfolding distribution, identifies abnormal reflection areas of defects such as debonding, hollowness and cracks based on the B scanning image and the C scanning image, and realizes defect positioning, quantitative evaluation and report output by combining echo characteristics.

Description

Laser ultrasonic scanning system for detecting basin-type insulator Technical Field The invention belongs to the technical field of nondestructive testing, and particularly relates to a laser ultrasonic scanning system for detecting a basin-type insulator, which is used for detecting the defect of the basin-type insulator. Background The interior of a basin-type insulator which is widely used in the current power system is generally formed by bonding a plurality of layers of materials such as epoxy resin materials and metal connecting pieces, and the interface bonding quality is directly related to the mechanical strength and the long-term operation reliability of the insulator. Once the resin-metal interface has the defects of debonding, hollowing or cracking, and the like, the electrical performance is easily reduced, and even serious accidents such as insulator bursting, flashover and the like are easily caused, so that the high-sensitivity nondestructive detection of the internal interface defects of the insulator is urgently needed. The existing engineering mainly adopts the methods of power frequency withstand voltage, sampling destructive inspection, conventional piezoelectric ultrasonic, X-ray and the like to carry out insulator quality detection, but the former two methods need to cut power or destroy samples, the efficiency is low, the cost is high, the piezoelectric ultrasonic detection depends on a coupling agent and a rigid transducer, the piezoelectric ultrasonic detection is difficult to adapt to the large curvature surfaces of insulator umbrella skirts and basin-type structures, poor coupling, acoustic beam deflection and energy scattering are easy to occur in a multi-layer bonding structure, and the detection rate of deep buried small defects is limited. The laser ultrasonic technology utilizes high-energy pulse laser to non-contact excite broadband ultrasonic waves on the surface to be detected, and receives surface vibration signals through an optical means to form an all-optical nondestructive detection system. The technology has the advantages of no need of couplant, high spatial resolution, long-distance arrangement, adaptability to extreme environments such as high temperature, high pressure, strong corrosion and the like, and has higher sensitivity and resolution than the traditional ultrasonic wave in the detection of interface layering and debonding defects of the multilayer composite material. However, the existing laser ultrasonic system is multi-faced to the research of structures such as aviation composite plates, pipelines and the like in a laboratory, has large equipment volume and single scanning mode, and is difficult to meet the engineering requirements of mass detection and efficient screening of insulators due to the lack of a special detection device and an automatic application scheme for axisymmetric curved surface multi-layer bonding members such as insulators. Meanwhile, the conventional system mostly adopts a translation or two-dimensional scanning platform to drive the laser and the detector to move, is not suitable for detecting any posture of the basin-type insulator in space, and is also a problem which remains to be solved in the prior art when the stability of the laser ultrasonic signal and the interface defect recognition precision are maintained under the complex working conditions of surface pollution, water stains and the like. Disclosure of Invention In view of the above, the invention provides a laser ultrasonic scanning system for detecting a basin-type insulator, which is a mechanical arm clamping and laser ultrasonic scanning system facing to a basin-type insulator curved surface structure, and aims to overcome the following problems in the prior art: The traditional ultrasonic flaw detection relies on a coupling agent and a contact probe, so that stable coupling is difficult to realize in a complex curved surface and a narrow gap of a basin-type insulator, and the sensitivity and reliability of detecting hidden defects such as internal debonding and cracks are insufficient; the automatic degree is low, the existing detection is dependent on manual handheld probes and mechanical adjustment, the operation process is complex, the repeatability is poor, and the consistency nondestructive detection of a large number of insulators is difficult to realize; The adaptability to complex space postures is poor, the posture of the basin-type insulator is changeable in the actual installation environment, the space is limited, and the traditional fixed type or two-dimensional scanning mechanism is difficult to realize full-circle coverage and multi-angle scanning; The curved surface scanning track is difficult to accurately control, and the lack of a motion coordinate system unified with the geometric central axis of the insulator and high-precision scanning track planning lead to unstable laser excitation and receiving positions and influence defect imaging an