Design For Unit Of Laser Welding Of Body-in-white And Research On The Performance Of Lap Welding Joints

with extensive use of laser welding technology in the automotive bodymanufacture, laser welding gradually replaces the traditional welding process.Compared with traditional welding methods, laser welding technology can reducethe body material consumption and body weight and improve assembly precisionand rigidity of the body, and then improve the safety performance of the body.Though laser welding technology has acquired great progress in China, there is stilla wide gap when compared with foreign countries in the automotive manufacturingapplication. At present, the complete laser processing equipment and technology ofbody welding are mainly introduced from overseas. And some manufacturersdirectly import laser processing components from overseas. Research anddevelopment of our own brand laser welding auto-body production line start lateand develop more slowly, which hinder the promotion of laser high-tech applicationand restrict the level of laser industry. The research of car body welding productionline and welding technology will be made in this project. It has important strategicsignificance to enhance the integration capacity of manufacturing equipment andimprove development of national auto industry.This paper reviews the research situation at home and abroad.The overalllayout of laser welding production unit of autobody is preliminarily designed.Laser welding auto body parts experiment is made in the above-mentioned laserwelding unit. For the fiber laser welding and CO₂laser welding of the galvanizedsteel sheet, the comparative analysis of performance is done as an emphasis.Firstly, the structure of body-in-white parts and manufacturing process floware analyzed. According to the principle of advanced technology, economicrationality and Suitable for the production, the major equipments on laser weldingunit are selected and designed. Based on production unit security considerations,the overall layout of laser welding production cell is designed. At the same time,physical simulation of welding unit and technological feasibility analysis is done.Secondly, after the appropriate welding parameters selected, the bumpers ofdoor sub-assembly are welded by resistance spot welding and fiber laser welding,respectively. Referring to the arrangement of resistance spot welding joints, weldlayout scheme of fiber laser welding bumper is put forward. When the welding testis completed, comparative analysis of dynamic stiffness of resistance spot welding and laser welding bumpers is done with LMS Vibration tester. By collecting thedata, the first three natural frequencies and vibration modes of the free mode areobtained, and then the welding quality of bumper is evaluated.Finally, the performance of fiber laser welding and CO₂laser welding of thegalvanized steel sheet are compared with each other. For the different plates lapjoint ways, by means of designing different length of laser seam, the influence ofthe laser weld joint length on the mechanical properties of the lap joint due to thechange is analyzed. Through dealing with Tensile-shear test data, mechanicalproperties law of different galvanized steel sheet lap joint which is influenced bytwo types of lasers is summarized. In addition, the microstructure and hardness offiber laser welding joints and CO₂laser welding joints are compared. Results showthat the microstructure of fiber laser welding joints is more homogeneous andsmaller than CO₂laser welding joints, and hardness is higher than that of the CO₂laser welding joints.