Research On The Expert System Of The Ultrasonic Testing Data Evaluation For Resistance Spot Welding Joint

Resistance spot welding with high production efficiency, the welding of low cost, highdegree of mechanization and automation, etc. has been widely used in the railway vehicle,automotive, aerospace and other fields. melting nucleus formation and growth of resistancespot welding process are done in a closed environment, does not directly observed, there arelots of uncertain factors in the welding process the effect of all these caused major difficultto resistance spot welding quality inspection.The traditional resistance spot welding joint quality detection methods are mainlycomposed of destructive testing, one of the most widely used destructive testing method isbased on the welding test piece or destructive tear experiment, this method can only obtainthe roughly quantitative information of spot size and work intensity, moreover the methoddetection efficiency is low, cause waste of materials, increase the cost of production. anotherkind of destructive testing method is to use the macro metallographic testing for moltennuclear diameter size, this method is relatively accurate, but a longer operation is complexand time consuming. So be realized without breaking resistance spot welding needs tonondestructive testing of spot welding joint, NDT methods of resistance spot welding is themost widely used in ultrasonic testing. Ultrasonic testing applications with easy, using awide range of fast, sensitive and efficient, etc. the ultrasonic testing in resistance spotwelding quality inspection more and more be taken seriously, has an important significanceand value in the practical production.Ultrasonic scan images of spot joint can effectively reflect the parameter information ofmolten nuclear, such as molten nuclear size, roundness and so on. but there are manyinfluence factors in resistance spot welding ultrasonic testing image, in order to be able tomake an accurate assessment of the quality of melt nuclear, need to establish a standardmodel of resistance spot welding ultrasonic C scan images for solder joint image qualityassessment in general. this paper developed the resistance spot weld ultrasonic testing expert system to realize quality evaluation of solder ultrasonic testing image, the expert system caneffectively handle resistance spot welding ultrasonic testing data to generate solder meltnuclear images, and through the analysis of ultrasonic scan images to realize fast matchingof solder joint image, finally finish the evaluation work of resistance spot welding quality.This paper constructs the resistance spot welding ultrasonic testing device, using thedevice for solder joints Ultrasonic scanning and ultrasound scan data. using resistance spotwelding expert system for ultrasonic detection to extract the characteristics of ultrasonicecho signal A worth to solder melt nuclear C scan images, and then through the study of thegray level transformation of ultrasonic C scan images, the threshold, edge detection and Aseries of technical processing to obtain the rough outline of weld nugget, and ultimatelymeasured resistance spot welding molten nuclear size. real value of nuclear size is obtainedby measuring spot welding metallographic image, using expert system for comparing themeasured value and true value to find the measured value, improved algorithm to achievestability and precision of measurement value of expert system.Through a lot of solder joint data collection, established standard solder joint imagemodel, in accordance with the roundness, aspect ratio and melt nuclear area and perimeterusing standard solder joint image model to realize solder melt nuclear image matching, andfinally realize the welds quality evaluation quickly.