Numerical Simulation Of Welding Distortion Of Draft Sill By Hybrid Laser Welding

The subway is a public rail transit that rises with the development of the city and is being welcomed by more and more cities.Draft sill is an important part of subway vehicle chassis,mainly through a large number of welding processing.However,welding distortion is always accompanied by the welding process,the product will be assembled,life and safety impact,so the need for control of welding deformation.In this paper,the draft sill of the subway vehicle chassis is used as the research object,and the welding deformation of the draft sill under different welding sequence and welding constraints is simulated by SYSWELD software to select the smaller welding process.The main contents of this paper are as follows:Firstly,the background and significance of this paper are described.The methods of welding deformation control are briefly described from the aspects of design measures and process measures.The simulation of welding and the numerical simulation of laser-MIG hybrid welding of current research situation are reviewed.Secondly,the commonly used theory of welding numerical simulation,heat source type and software for a brief introduction.Thirdly,the welds of draft sill are classified.According to the actual welding process,based on the thermo-elastic plastic method of different welding joints for heat source fitting,so that the test with the weld section is basically the same,and then extract the joints of the inherent strain.Then,the extracted inherent strain value is applied to the traction beam by the equivalent temperature method,and the calculated deformation is compared with the actual measured deformation.Finally,three different welding constraints and three different welding sequence processes are selected in this paper to optimize the welding deformation of draft sill.The results show that the simulated weld section is very close to the experimental section when using 3D Gaussian and double ellipsoid heat source model to simulate laser-MIG composite welding,and this verifies the correctness of the heat source model selection.Under the same welding process conditions,a good agreement between the simulation results and the actual measured deformation results was obtained.The relative error is 8.23%.It is proved that the inherent strain method is used to estimate the welding deformation is feasible.Different welding constraints and sequences have an effect on the welding deformation.After the draft sill welding,there are different degrees of angular deformation,shrinkage deformation and flexural deformation.The angular deformation of the draft sill is reduced by up to 76.95%when the welding constraint is changed as described in the text,and the shrinkage deformation is reduced by up to 8.00%when changing the welding sequence.