Research On Automatic Inspection And Evaluation Method Of Complex Weld Appearance Quality

As an important material forming process,welding plays a very important role in many industrial manufacturing fields such as automobile,marine and aerospace.The welding quality can fundamentally affect or even decide the final quality of the whole product,and the appearance quality of the weld is an important part of the welding quality.Therefore,it is of great significance to carry out weld appearance quality inspection for welding products to ensure welding quality.In the field of heavy welding tasks,such as automobiles,marine,pressure vessels and heavy equipment,there are many complicated structure and irregularly shaped weld forms,which bring certain challenges to weld appearance quality inspection.Up to now,the traditional weld appearance quality inspection method is manually inspected by experienced inspectors with simple inspection tools,which has poor accuracy,low efficiency,and relies on personal subjective judgment to a certain extent.With the development of the manufacturing industry,the requirements for the quality of welding products have gradually increased,the above methods can no longer meet the actual needs.It has become an inevitable trend to develop automatic and intelligent weld appearance quality inspection means.In this paper,an automatic inspection and evaluation system for the appearance quality of complex weld based on industrial robots and equipped with two-dimensional laser ranging sensor was developed to realize the automatic inspection of the appearance quality of complex welds in the industrial field,in response to the problem of difficulty of complex weld appearance quality inspection.The hardware part of the system is composed of industrial robots,industrial computers and two-dimensional laser ranging sensors,etc.The main functions of the software part include inspection control,robot communication,sensor communication,weld appearance dimension detection and calculation,three-dimensional imaging and quality assessment.In order to determine the spatial positional relationship between the coordinate system of the two-dimensional laser ranging sensor mounted on the end flange of the industrial robot and the robot coordinate system,the transformation mode of the threedimensional coordinate system was analyzed,the hand-eye calibration experiment was carried out,and the accuracy of the hand-eye matrix was verified.The test results showed that the accuracy of hand-eye matrix meets the requirement of inspection system.For the typical complex welds of rail train bogies,the processing methods of complex weld appearance inspection data were studied,including weld appearance data acquisition,coordinate transformation,tilt correction and feature point extraction.As the center of the inspection system,the industrial computer establishes the communication with the industrial robot and the two-dimensional laser ranging sensor simultaneously,and obtain information about both in real time.The industrial robot is equipped with the sensor to move freely in the inspection space.According to the shape characteristics of the complex weld being measured,it can complete a non-contact comprehensive scan on the surface of the weld,obtain the profile data of the weld appearance,design an algorithm to process it,calculate the quality parameters of the weld appearance,output the three-dimensional point cloud of the weld appearance,and select the relevant welding quality database as a reference to judge the overall surface quality of the complex weld.The test results showed that the automatic inspection and evaluation method of the appearance quality of complex welds proposed in this paper is feasible,the calculation results of weld appearance size,three-dimensional point cloud and quality evaluation results are consistent with the actual situation,which has certain application value for improving weld quality and welding production efficiency.