Real-time Ultrasonic Inspection System For Lap Laser Welding

With the continuous improvement of the requirements for safety,energy saving,anticorrosion,and maintenance performance of railway passenger cars,stainless steel materials have been widely used in the railway passenger car industry due to their high strength,high toughness,light weight,corrosion resistance and other technical characteristics.The side wall of stainless-steel bus mainly adopts the semi-permeable lap laser welding method,that is,the workpiece steel plate under the action of the laser is fully permeated,and the lower steel plate is in a semi-permeable state.In the welding process,the quality of the weld is often affected by welding parameters,and defects such as pores or insufficient weld penetration may occur.The commonly used quality assessment method is non-destructive testing,but this method of testing after production will reduce production efficiency and increase costs.Aiming at the quality problem,this paper developed an online inspection system for laser welds of overlapping structures.The integrated welding inspection system includes a six-axis manipulator laser welding part and a three-axis ultrasonic phased array inspection part.In ultrasonic testing,in order to solve the problem of low imaging efficiency and inadequacy for real-time imaging due to the large amount of data collected,transmitted and calculated by the all-focus imaging algorithm,a triangular matrix imaging algorithm was proposed based on the reciprocity of each ultrasound channel to make the phase control the amount of data collected and calculated by the array has been reduced by nearly 1/2,and the efficiency has doubled.Then according to the increase of the distance from the transmitting element to the receiving element,the energy of the A signal received by the receiving element will gradually decrease.The trapezoidal matrix imaging algorithm is proposed,which greatly improves the imaging efficiency while ensuring the imaging quality.In terms of automatic control of welding and inspection,we have compiled linear and curved seam motion trajectory interpolation algorithms and quaternion space attitude interpolation algorithms to control welding six-axis manipulators and inspection three-axis mechanisms to achieve linkage control of space given welds,and the speed of the motion process Smooth and efficient.The welding and inspection integrated system carried out welding and inspection experiments on the stainless-steel plate overlap structure,and used the automatic control system to combine the manipulator and the three-axis motion system to achieve synchronous movement.The welding process is stable and controllable,the ultrasonic inspection results are clearly imaged,and the fusion state and weld width can be accurately displayed.