Modeling, identification and simulation of DC resistance spot welding process for aluminum alloy 5182

Currently the aluminum alloy resistance spot welding (AA-RSW) has been extensively used for light weight automotive body-in-white manufacturing. However the aluminum alloys such as AA5182 have inferior weld ability for forming the joint due to their high reflective ness to heat and light. Therefore it is necessary to further develop the high performance control strategy and the set-up of a new welding schedule. The welding process identification is the essential issue where the difficulty arises from the fact that the AA-RSWis a nonlinear time-varying uncertain process which couples the thermal, electrical, mechanical and metallurgical dynamics. To understand this complicated physical phenomenon a novel dual-phase M-series pseudo-random electrical pattern is adopted to excite the AA-RSW electrical-thermal process and the thermal response is recorded according to the welding power outputs. Based on the experimental information, the transfer function of an AA-RSW electrical thermal mechanism is identified, and the optimum model order and parameters are determined. Subsequently a control-oriented DC AA-RSW model is established to explore the welding power control algorithm. The simulated results of the control model show agreement with the experimental data, which validates its feasibility for the corresponding welding control.