高强钢变厚板汽车B柱热成形数值模拟及主要参数分析

Numerical Simulation and Main Parameters of Hot Forming of B-pillar of High-strength Steel Variable-thickness Plates

目的研究热成形过程中冲压件温度场、应力场的变化规律,探究主要工艺参数对冲压件成形的影响规律。方法利用Abaqus软件建立热力耦合模型,对汽车B柱的热冲压成形过程进行数值模拟,分析板料及模具的温度和应力变化,确定主要工艺参数对冲压件的影响规律,利用得到的规律指导B柱模具的设计与制造,最后对B柱进行冲压试验。结果在热成形前的物料转移阶段,板材厚度差的存在使过渡区产生了温度梯度和内应力的变化;在热成形阶段,以减薄率为评判标准,确定了摩擦因数为0.35、冲压速度为100 mm/s时B柱的成形效果最好;对B柱的成形结果进行了分析,由局部减薄率的变化得到了模具缺陷的位置,由过渡区的偏移量得到了模具等厚区的长度,由板材温度变化确定了最佳保压时间为8 s。结论基于Abaqus软件,构建了B柱的热冲压有限元模型,对板材出炉至成形结束阶段进行了数值模拟与分析,在此基础上对B柱制件进行了冲压试验,发现制件的质量缺陷明显减少,对制件的指定点进行了面检测,合格率达到了95.83%,表明了分析结果的可靠性,同时也验证了有限元分析的准确性。

The work aims to study the change law of the temperature field and stress field of stamping parts in hot forming,and explore the effect law of the main technological parameters on the forming of stamping parts.The thermal coupling model was established through the Abaqus software,and the hot stamping process of automobile B-pillar was numerically simulated.The temperature and stress changes of the plates and dies were analyzed,and the effect law of main technological parameters on stamping parts was determined.The obtained law was used to guide the design and manufacture of the die of B-pillar,and finally the stamping test was carried out on the B-pillar.In the material transfer stage before hot forming,and the difference of plate thickness caused the temperature and internal stress changes in the transition zone.During hot forming,and the best forming effect was determined when the friction coefficient was 0.35 and the stamping speed was 100 mm/s with the thinning rate as the evaluation standard.The forming result of B-pillar was analyzed.The location of die defect was obtained according to the change of local thinning rate,the length of die equal thickness zone was obtained according to the offset of transition zone,and the optimal pressure holding time was determined to be 8 s by the change of plate temperature.Based on the Abaqus software,the hot stamping finite element model of B-pillar is constructed,and the numerical simulation and analysis are carried out on the plate from the release to the end of forming.On this basis,the stamping test of B-pillar is carried out,and it is found that the quality defects of the parts are reduced obviously.The surface detection of the designated points of the parts is carried out,and the qualified rate reaches 95.83%,which shows the reliability of the analysis results and verifies the accuracy of finite element analysis.