A MIG Welding Clamping Scheme for Power Battery Enclosure’s Deformation Restrain

Abstract

Aiming at the inward shrinkage between the frame and the bottom plate of the power battery enclosure after MIG (melt inert-gas) welding, a welding clamping scheme with hook-pull devices was designed. By adjusting the clamping force of the hook-pull device, the MIG welding deformation force was counteracted, so the inward shrinkage deformation of the frame after welding was restrained. To obtain the deformation force during the MIG welding, the welding simulation model of power battery enclosure was established. Gaussian heat source model was selected as temperature load. Through the numerical simulation and experimental analysis of the temperature field, the numerical simulation results are in good agreement with the measured thermal cycle curve in terms of temperature value and change trend. The error between numerical simulation result curve and measured thermal cycle curve at the measurement point is no more than 10%, which can meet the simulation requirements. Based on the simulation model and the load of the temperature field, deformation force curves were obtained by simulating the welding process. To counteract the MIG welding deformation force, a pneumatic servo control system of the welding clamp was designed, which can generate equal and reversed welding deformation force. The experiments show that the actual output force of the system has a tiny time delay and fluctuates with the varies of the pneumatic servo control system. The maximum fluctuation error is 6.96 N, which is within the permitted error range. The welding experiments were carried out to verify effectiveness of the control system and the welding clamp. The field results have shown that the maximum inward shrinkage deformation after welding is 0.6 mm, which is less than 1.2 mm required by the MIG welding process.