Abstract
In order to meet the requirements of alignment capability, gap tolerance and welding track control, dual-beam laser welding has been put forward to weld tailored blanks with different thicknesses. The arrangement mode and power ratio of dual-beam laser determine the heat transfer and temperature field distribution, and then influence the weld profile and weld quality. In this study, based on consideration of the temperature dependence of material physical properties, convection and radiation heat transfer, and material latent heat, the finite element model was developed. The model validated was conducted to compare with experimental results and it showed good agreement. The arrangement mode and power ratio of dual-beam laser welding were compared and optimized based on the consideration of the weld width on top surface and gap tolerance. Finally, the temperature field characteristics with the preferable process were analyzed in detail according to the numerical simulation. The calculated results indicated the weld width is mainly controlled by the laser irradiation on the thin plate, and dual-beam laser welding of tailored blanks has great advantages on improving heat transfer, weld profile and gap tolerance, which helps to reduce welding defects and enhance welding quality.
Highlights
Tailor-welded blanks (TWBs) technology is widely used in car body manufacturing, which are defined as tailored blanks with different thicknesses, material or properties welded together and formed
III, oneinlaser beam irradiates on the thicktailored plate and the other laser beam on laser arrangement mode III, one laser beam irradiates on the thick plate and the other laser beam on the thin plate, and the line connecting the dual-beam laser focused spot centers inclines to the welding direction at an angle of 45°
A hybrid heat source model consisted of one surface heat source and double body heat sources was established, namely, the plasma above the workpiece was considered by a surface heat source and heat transfer of double keyholes in the weld pool was simulated by two cylindrical heat sources
Summary
Tailor-welded blanks (TWBs) technology is widely used in car body manufacturing, which are defined as tailored blanks with different thicknesses, material or properties welded together and formed. Tailored blanks have been welded using many welding methods [4,5,6,7,8,9,10,11]. Owing to the high welding velocity, low welding thermal distortion and high operation flexibility, the research of tailored blanks welding has been mainly focused on laser welding in past decades. Because the diameter of the laser beam focused spot is small, the requirements for alignment capability, gap tolerance and welding track control are very high during single laser welded tailored blanks. Dual-beam laser welding has been put forward to weld tailored blanks with different thicknesses to solve the above problems [12]
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