Experiment Research And Numerical Simulation On Laser Transmission Welding Of Thermoplastic

More and more people are highlighting laser transmission welding of thermoplastic because of so many advantages, such as excellent welding quality,easy to control,available for micro-welding and so on. The foreign industrialization and patents about laser transmission welding of thermoplastic are good enough, but because of keeping secret, there aren't enough theory research studys. The domestic people have already known the huge application prospect of laser transmission welding of thermoplastic, however, there are few domestic study on this research subject, which results in huge gap between domestic and foreign study on theory,industrialization and patents. Therefore, starting research on laser transmission welding of thermoplastic has significant theory meaning and application prospect.Focusing on the mechanism of laser transmission welding of thermoplastic, using the method of experiment and numerical simulation, using transparent PS and PVC material, this thesis carries the studies as follow:First of all, the optimal factors that fit to laser transmission welding of transparent PS and PVC are found with Orthogonal Experimental Design. Studying the relationship between factors and the welding strength, which indicates subsequence according to influence for PS is welding velocity→laser average power→beam diameter→dwell time→laser frequency→fixture pressure; the subsequence for PVC is welding velocity→laser average power→laser frequency→dwell time→beam diameter→fixture pressure, this thesis offers the practical instructions to develop the welding quality. Laser transmission welding is used between two kinds of different materials (PS and PVC) successfully. The optimal factors are received, and quantitative analysis is prosecuted. The subsequence according to influence for PS and PVC is welding velocity→fixture pressure→beam diameter→laser average power→laser frequency→dwell time. The samples which are welded with black lacquer and Clearweld additive are compared from welding strength and appearance quality, which indicates that Clearweld additive is better than black lacquer additive. The phenomenon of black and brown welding line, welding line heave, jointing rupture is analyzed.Secondly, by finite element analysis method, the calculating model of simulation of laser transmission welding of thermoplastic is built. The temperature field and stress field are simulated. The influence of welding velocity, laser average power and beam diameter on temperature field and stress field is discussed, and simulation results are accordinig with experimental result. By numerical simulation, the size of melted pool can be controlled, and technique parameters can be optimized, which provide new methods for researching on welding mechanism, and provide criterion for enhancing welding precision.