Process Research And Numerical Simulation Of Laser Transmission Welding Plastic

With great performance and sufficient source, plastic is being used more and more widely. Complex-shaped plastic goods are required in industry sometimes, and it cannot always rely on the method of molding. However, traditional connecting methods have many disadvantages. Laser welding is being widely recognized because of its advance, efficiency and less pollution. Therefore, it is of great significance to do the research on laser transmission welding plastics.According to the theory of laser transmission welding (LTW), this thesis uses the method of process experiment combining with numerical simulation, and made a rather systematic research on the subject.Firstly, this paper analyzed the main elements which have an influence on welding quality, and chose laser power, welding speed, spot diameter and pulse frequency to be researched. Orthogonal experimental method is used to design the experiment schedule. After the experiment, welding strength and weld width are tested to evaluate the welding quality. Using the range method, the optimal process parameters were found. Furthermore, the influence of different elements on welding strength and weld width are analyzed. Laser power and welding speed are more important to welding strength, while spot diameter and welding speed to weld width. The result gives a direction on what should be firstly considered for different situations.Secondly, took use of the method of finite element simulation and the ANSYS software, and the paper made a numerical analysis on laser transmission welding plastic. A calculation model was built which suits for the heat conduction of LTW. This model simulates the temperature field and stress-strain field of LTW, and research the change of temperature and material property during this process. By using this model, the size of weld pond can be controlled and better process parameters can be found. It provides a new way to research the welding principle and laid a theoretical foundation for improving welding precision.