Experimental Research Of Laser Welding Automobile Body-in-white Galvanized Steels With Robot

Laser welding is a mature technology widely used in automobile body manufacturing of the industry developed countries. Using the technology of robot laser welding automobile body-in-white to replace the traditional automobile body-in-white resistance welding process, can not only enhance welding quality and improve the mechanical properties of body parts, but also save materials to greatly reduce the body's production costs. The world's leading automotive companies have used the robot laser welding technology for their car body production. Until 2000, 50% of the body parts spot welding lines of three major U.S. automobile companies have been replaced by robot welding line. As the products of automobile joint ventures in China are now entering production stage with foreign synchronization, laser welding technology and equipments are applied accordingly. Robot laser welding technology has played an irreplaceable role in these joint ventures, and been accepted as an advanced manufacturing technology in the industry. However, with mainly importing complete sets of equipments or production lines from abroad, research and development of laser welding car body production line of own-brand automobiles started late, and development is slow and still blank. China has still not established a complete production line of the body parts of laser welding, and the parts requiring laser welding can only be imported from abroad. Many companies request that they are eager to have cost-effective robot laser welding production lines to replace importing a large number of laser processing components from abroad and develop products with independent intellectual property rights to improve the quality and competitiveness of our cars. The present study has strategic importances of improving equipment manufacturing enterprises' integration capabilities, and promoting the development of national auto industry.Robot laser welding system is composed of highly flexible six-axis robot, fiber laser, laser welding head and fixtures. First, analyse theoretically the principle of laser welding automotive body-in-white galvanized sheet materials and main process factors. Then, carry out experiments to test various process factors by moving robot and controlling robot, analyse these factors' effects on the quality of welding process, and conclude a reasonable set of welding process parameters.Experiments are divided into two parts. One is the experiments of robot laser lap welding body-in-white galvanized sheets, and then test the mechanical properties of weld joints (tensile strength, microstructure observation, hardness), and conclude that the strength and hardness of laser welding joint is higher than the base metal. The other is the three-dimensional experiments of robot laser welding body-in-white galvanized inner door panel assembly, and then evaluate the quality of welding from the perspective of whether welding defects exist, and analyze the causes of welding defects and measures of reducing defects.