Study On Hot Die And Process Parameters For Hot Plate Welding Of Car Light Based On CAE

Hot plate welding is used widely because of its widespread applicability,usability,high precision and so on.Improper process parameters will lead to various weld defects such as incomplete fusion,lack of penetration,slag inclusion,stoma and excessive residual stress,which may warp the car light,cause polymer craze even crack,decrease the welding strength.So the rate of good product is influenced.Based on finite element simulation analysis and experimental validation this paper does research of hot die and process parameters for hot plate welding.Here comes main research work:(1)The thermal conduction and thermal-structural coupled simulation models of hot die and car light lens were built.The three-dimensional models of hot die and car light lens were simplified properly and boundary conditions of load and constraint were applied by actual conditions,such as the expression of heat source in hot die.The finite element simulation analysis of hot die’s heating process was carried out,compared with temperature and deformation measured in experiment,the analysis was proved to be feasible and valid.(2)Aimed to reduce heating time and deformation of hot die,improve temperature distribution of heating rib surface,the scheme of lightening weight of hot die is put out to give out improving structure scheme.And the scheme of heat source in hot die is graded power,which effectively contributes to decreasing temperature difference,increasing heating efficiency.Also it is beneficial to reducing deformation of hot die and enhancing its repeated positioning accuracy.(3)Thermal contact resistance is gotten by experiment and the thermal simulation analysis of car light during hot plate welding is carried by thermal contact element,which conduces to understanding the effect of welding temperature and heating time on welding quality of car light.In addition,it can make the range of welding temperature,heating time and welding depth.(4)The welding strength of car light is setted as optimization objective and welding temperature,heating time,welding depth are setted as optimization variables,by which the optimization mathematical model of welding parameters for car light is established.The orthogonal test design is adopted to conduct the welding tensile test on the specimens of two kinds of materials.The test data is processed through the signal-to-noise method and range analysis,then the influence degree of the three factors on the welding strength and the optimal combination of process parameters are obtained.In a word,aiming at the problems existing in the process of hot plate welding of car light this thesis establishes the thermal-structural coupled simulation models of hot die and car light lens,based on which the CAE simulation of heat transfer and thermal-structural coupled analysis are carried out.After then the improved designs for hot die and power distribution of heat source are given.Then experimental scheme is designed to verify the accuracy of the simulation.Lastly the optimization mathematical model of welding process parameters of car light is established.Through orthogonal test,the optimal combination of welding process parameters of car light is obtained.The work in the thesis is beneficial to improve the temperature distribution and heating efficiency of hot die and increase the welding quality of hot plate,which is of great significance to the manufacturing technology of car light.