基于激光拼焊技术车身B柱轻量化设计分析

Lightweight Design Analysis of B-Pillar of Car-Body Based on Laser Welding Technology

B柱是侧面碰撞的关键承载结构件,对整车安全性具有重要影响。基于B柱可制造性工艺分析模型,对B柱进行成形工艺分析;在保证成形工艺的前提下,对B柱进行激光拼焊设计;对拼焊的材料和厚度进行分析;在此基础上,对激光拼焊的焊缝位置进行设计;基于整车侧碰安全性分析模型,对获得的拼焊设计方案进行碰撞安全性分析,对比优化设计前后的侵入量和侵入速度;依靠激光拼焊方案量产车型,对激光拼焊B柱的轻量化效果和安全性进行分析,并对设计过程的可靠性进行验证。结果可知:B柱零件的上部选用DP780,下部采用DP590,且上下的板厚差不超过0.6mm,可以满足激光拼焊成形要求,焊缝的位置距离B柱低端370mm时,减薄率最低为21.1%;激光拼焊设计与原设计安全性基本保持一致,各测点指标的误差小于3%;原设计方案B柱的总量为21.3kg,而激光拼焊方案B柱的总量为17.5kg,轻量化减重达到21.7%;激光拼焊方案实测结果满足碰撞要求,侵入量最大值为137.8mm,侵入速度的最大值为4.33mm,均小于最大限值;仿真分析和实测各个测点的结果保持基本一致,侵入量的最大误差为5%,而侵入速度的最大误差为5.4%,表明模型仿真分析结果的可靠性,为此类设计提供参考。

B-pillar is the key load-bearing structure in side impact,which has an important impact on vehicle safety.Based on the manufacturability process analysis model of B-pillar,the forming process of B-pillar was analyzed.On the premise of ensuring the forming process,the B-pillar was designed by laser tailor welding.Based on the vehicle side impact safety analysis model,the impact safety of the obtained tailor welded joint design scheme is analyzed,and the intrusion amount and intrusion speed before and after the optimization design are compared.Based on the mass production model of laser welding scheme,the lightweight effect and safety of laser butt welding B-pillar are analyzed,and the reliability of the design process is verified.The results show that:the upper part of the B-pillar is DP780,the lower part is DP590,and the thickness difference between the upper and lower parts is not more than 0.6mm,which can meet the requirements of laser tailor welding.When the position of the weld is 370mm away from the lower end of the B-pillar,the minimum thinning rate is 21.1%.The safety of the laser tailor welding design is basically consistent with the original design,and the error of each measuring point index is less than 3%.The total amount of column B in the original design scheme is 21.3kg,while that of laser welding scheme B-pillar is 17.5kg,and the weight loss of light weight reaches 21.7%.The measured results of laser tailor welding scheme meet the requirements of collision,the maximum value of intrusion is 137.8mm,and the maximum value of intrusion velocity is 4.33mm,which are less than the maximum limit.The results of simulation analysis and actual measurement are basically consistent.The maximum error of intrusion amount is 5%,while the maximum error of intrusion velocity is 5.4%.It shows the reliability of the model simulation analysis results,and provides a reference for this kind of design.