汽车纵梁液压成形模拟研究

Simulation study on hydroforming for longitudinal beam of car

为探究汽车纵梁液压成形规律,并为其工程化应用提供必要的指导,对方形管进行脉动液压成形实验及数值模拟,并通过实验验证模拟的正确性。首先明确纵梁液压成形工序及主要参数,然后对其成形全过程进行仿真研究,最后基于此分析了液压加载路径、成形模具与管坯接触面间摩擦系数对纵梁液压成形壁厚分布及成形件最大减薄率的影响规律。结果表明：在常规加载中,前期增压至成形压力值一半左右,并进行一段时间的保压,后期升压至成形压力,其加载路径下的成形构件最大减薄率最小,壁厚分布整体最均匀;在此加载路径基础上,采用脉动加载可进一步提高其成形质量;同时,摩擦系数越小,成形最大减薄率越小,整体壁厚值越接近初始管坯值且分布越均匀。

In order to study the hydroforming regulation of longitudinal beam of car and provide the necessary guidance for its engineering application,the experiment and numerical simulation of the pulsating hydroforming rectangular tube were carried out,and the correctness of simulation was verified by experiment. Then,the hydroforming process and main parameters of the longitudinal beam were confirmed,and the whole process of forming was simulated. Based on the above facts,the influences of hydraulic loading path and friction coefficient of contact surface between die and tube on the wall thickness distribution and the maximum thinning rate of the longitudinal beam in hydroforming were analyzed. The results show that in conventional loading the pressure is increased to approximately half of the forming pressure in the early stage,maintained for a period of time,and then increased to the forming pressure in the later period. In this loading path,the maximum thinning rate is the smallest,and the wall thickness distribution is the most uniform. Based on the above loading path,the pulsating hydroforming loading path can further improve the quality of longitudinal beam. At the same time,the smaller the friction coefficient is,the smaller the maximum thinning rate of forming is,the closer the wall thickness to that of initial tube is,and the more uniform the wall thickness distribution is.