Numerical Simulation And Technology Research Of High Frequency Microvibration Laser Welding

Laser welding has been widely used in modern industrial production. Its efficient, fast and flexible technology feature makes it can be apply to the field of vehicle, manufacturing, aviation, shipbuilding very well. Vibration welding is developed on the basis of the VSR. With this kind of welding process, the microstructure of weld joint can be refined, residual stress and welding distortion of the workpieces can be reduced and the welding quality can be improved In combination with laser welding and vibration welding,the process characteristics of high frequency micro vibration laser welding was discussed in this article. With the software of ANSYS element analysis, temperature field, residual stress and welding distortion during the process of high frequency micro vibration laser welding can be simulated. Thermocouple temperature measurement method is used to measure the welding thermal cycle curve of relevant points on the workpiece, and blind-hole method was used to measure the transverse and longitudinal residual stress distribution of welding workpieces. The measured results and simulation structure were analyzed in this paper.In this paper, 316 austenitic stainless was selected for the experiment, the manner of symmetrical modeling was used in the test. During the simulation of temperature field of high frequency micro vibration laser welding, the laser power was 3000 W and welding speed was 0.025 m/s, double ellipsoid heat source model was selected for the simulation. As the effect of micro vibration on the temperature field is limited,the influence of micro vibration was ignored in the simulation of welding temperature field. Center temperature of the simulated welding temperature field is about 2106℃. Indirect coupling method was used in simulation of stress field. The result of the temperature field simulation was loaded into the work piece as a load. The time-varying vibration displacement which has been obtained by the means of harmonic response analysis was loaded as a boundary condition of the stress field simulation. Under the high resonance frequency, transverse and longitudinal residual stress of the workpiece was small, and the welding deformation is small.In the welding experiment, the welding joint microstructure and mechanical characteristics was contrasted under different vibration parameters. Simultaneously, the welding thermal cycle curve of relevant points on the workpiece and transverse and longitudinal residual stress was measured. Contrasted the results of test measurement and simulation, it shows that the error is within 10%, meanwhile, the curve of measured results and simulation results have a same change trend. Test of temperature field and residual stress value consistent with simulation results. By comparing the welding joint microstructure under different vibration parameters, it is found that the microstructure is finer, σ-ferrites and dot carbides are more diffuser under the high resonant frequency. And the micro-hardness of welding joint was increased with the introduction of vibration.