动力电池箱MIG焊夹具夹紧力动态调整方法研究

Research on Dynamic Adjustment Method of Clamping Force of MIG Welding Fixture for Power Battery Enclosure

作为承载和保护纯新能源汽车动力电池模组的关键部件,动力电池箱常采用MIG(Melt Inert-gas,熔化极惰性气体保护)焊接加工并由固定式夹具夹紧待焊件,由于夹紧力值固定,难以控制焊接变形、进而影响吊耳的焊装。以某型动力电池箱作为对象,设法通过控制焊接过程中夹具模块夹紧力的大小以改善焊接加工质量。首先,对焊接装夹方案进行模块化设计,通过有限元分析对焊接残余变形进行数值模拟,进而推导出抑制两侧横梁焊接变形所需的反作用力,以获取控制焊接变形所需的夹紧力;然后,基于模糊自适应PID算法设计夹紧力气动伺服控制系统,以准确跟踪电池箱焊接过程中的夹紧力目标曲线,并在AMESim与MATLAB/Simulink组成的联合仿真平台上对控制策略进行验证;最后,采用基于dSPACE的硬件在环实验系统,搭建等效实验平台对所提出的夹紧力动态调整方案进行验证。实验结果表明,所提出的夹紧力动态可调焊装方案夹紧力输出值与目标值误差低于7N,预期可有效改善MIG焊接加工变形,以达到焊接工艺规范要求。

As a key component of load bearing and protecting the power battery module in new automobile,the power battery enclosure is generally made through Inert-gas Welding and the parts to be welded is usually clamped by fixed fixtures.Welding deformation is difficult to control because the fixed clamping force,which will affect subsequent process such as welding of the lifting lug.A certain type of power battery enclosure was taken as the research object.Firstly,the modular design of welding fixture scheme was carried out,and the clamping force needed to control welding deformation was acquired through numerical simulating by adopting finite element analysis software.Moreover,the corresponding reaction force needed to restrain welding deformation of cross beams on both sides was deduced,as well as the needed control clamping force.Then,apneumatic servo control system was developed based on fuzzy adaptive PID algorithm.The proposed control strategy was verified on AMESim-MATLAB co-simulation platform,and the results has shown that the clamping force can tracking the proposed target curve accurately.Finally,a hardware in the loop experimental system based on dSPACE was set up to develop an equivalent experimental platform to verify the proposed dynamic adjustment scheme of clamping force.Test results have shown that the difference on clamping force value between the proposed scheme and the target one is less than 7 N,which will be able to effectively improve the quality of MIG welding deformation,and can fulfill the requirements on welling process specification.