| High Power Direct Diode Laser(HPDDL) is a novel laser system that can be used in welding, which has a few advantages such as short wavelength, small size, light weight, high efficiency of photoelectric conversion and reliable output, etc. Compared to CO2 laser and Nd:YAG laser, the HPDDL also has predominance for its special light spot geometry—strip light, which made HPDDL more tolerable to the gap of weld seam. Thus HPDDL has been widely used in manufacturing. In this study, the numerical analysis model of HPDDL process is developed with considering its process characteristics. And the model could be the basis for optimizing the parameters of this new welding process.To develop the numerical analysis model of thermal process in HPDDL welding, two types of heat source modes are proposed, one is parabolic-distribution mode and another is Gaussian-distribution mode. A dynamic non-uniform grid system is used to discrete the work piece. A computer program is designed with language Visual Fortran to realize the calculation of the quasi-steady state temperature field in HPDDL welding process. The program is successfully debugged and the simulation results demonstrate that the parabolic-distribution mode is more suitable to describe the HPDDL welding thermal process than the Gaussian-distribution mode.Numerical simulations of welding thermal process on thin steel plates are carried out for three welding conditions (output power1000W,685W,532W) by using parabolic-distribution mode of heat source. Some basic data of weld dimensions, thermal cycles and weld pool profiles are obtained. The results show that the predicted weld dimensions match with the experimental ones. Based on the welding pool images captured by a vision sensor, the predicted weld pool profiles are analyzed, and some factors that influence weld pool profile are discussed. |
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