Wave velocity and thickness calibrating method for ultrasonic wave welding spot detection

Abstract

The invention relates to a wave velocity and thickness calibrating method for ultrasonic wave welding spot detection. A test block of a corresponding material is selected for to-be-tested workpieces of different materials, the wave velocity calibrating error caused by different materials is minimally reduced; meanwhile, the invention provides thickness calibration for the to-be-tested workpiece, and the defect of existing detection equipment is made up from the application point of view. By adopting the technical scheme provided by the invention, aiming at wave velocity calibration of different materials and thickness calibration of different workpieces, the measurement accuracy is greatly improved, the measurement error caused by inaccurate wave velocity and thickness is reduced, and thus the data measurement is more reliable.

Description

field of invention [0001] The invention relates to a welding quality monitoring method, in particular to a method for calibrating wave velocity and workpiece plate thickness for ultrasonic welding spot detection. Background technique [0002] At present, most of the car body sheet metal parts adopt spot welding structure. With the increasingly stringent quality requirements of the market, many manufacturers are looking for non-destructive spot welding inspection methods, so a large number of OEMs have begun to use ultrasonic welding spot inspection equipment. The basic principle of this type of equipment is to combine the incident and reflection characteristics of ultrasonic waves, and use piezoelectric crystals to generate ultrasonic longitudinal waves, which are incident vertically into the weld nugget. The acoustic impedance of the analyzed material must be slightly different, so the longitudinal wave velocity is also different, and there must be errors between the actual...

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Problems solved by technology

The basic principle of this type of equipment is to combine the incident and reflection characteristics of ultrasonic waves, and use piezoelectric crystals to generate ultrasonic longitudinal waves, which are incident vertically into the weld nugget. The acoustic impedance of the analyzed material must be slightly different, so the longitudinal wave velocity is also different, and there must be errors between the actual value and the theoretical value of the plate thickness, and manually adjusting the ultrasonic velocity and thickness is a waste of manpower, low efficiency, and indirectly leads to an increase in production costs.

[0003] There are many detection methods for ultrasonic solder joint detection. In the article "Principle Analysis of Wave Velocity and Probe Delay Calibration of Digital Ultrasonic Detector" written by Li Shengping of Qinghai Electric Power Scientific Experimental Research Institute, the method of calibrating the wave velocity of ultrasonic detector with test block is described. , the technical solution in this paper is to calibrate the wave velocity of the detector through a test block, but in the actual detection process, the wave velocity must have a big difference in the sheet metal parts of different materials. Obviously, the method pointed out in this paper cannot To meet the engineering needs, in addition, in the process of engineering practice, it is often necessary to calibrate the thickness of the workpiece, and the existing technology does not provide an effective method for checking the thickness of the workpiece

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