基于热力耦合模型的拉深件连续冲压稳定性分析

Stability analysis on continuous stamping for drawing parts based on thermal-mechanical coupling model

在板料大批量连续拉深成形条件下,由于模具与板料表面之间的摩擦生热,模具内部热量积累导致温度逐渐升高,模具热膨胀作用改变了凸凹模间隙,对冷冲压件尤其是深拉件成形质量产生不利影响。基于典型圆筒形拉深件的热力耦合模型,通过有限元模拟和数学物理分析,研究其在连续冲压条件下模具温度及凸凹模间隙随冲压次数的变化规律。结果表明:连续冲压条件下初始阶段模具温升趋势明显,并逐渐减弱,直至趋于稳定,凸凹模间隙相应地随模具温度增加而逐渐缩减,显示了连续冲压稳定性的衰减。实际生产中可通过增设模具风冷或水冷装置、改善模具与板料之间润滑条件、降低冲压频率等措施提高连续冲压稳定性。

In the continuously massive drawing of sheet metal parts,due to frictional heat between dies and blank,the heat accumulation in the die results in the gradually rising temperature of die,then the thermal expansion of dies changes the clearance between die and punch,which has influences on the quality of cold stamping parts,especially deep-drawing parts. The variation of die temperature and die clearance under different stamping times for typical cylindrical deep-drawing parts in a continuous stamping process were investigated based on the thermal-mechanical coupling model by finite element simulation and mathematical analysis. The results indicate that during the continuous stamping,the die temperature rises sharply in initial stage and then gradually weakens to a stable condition. Correspondingly,the die clearance decreases with the increase of die temperature,which leads to a degradation of continuous stamping stability. In practical process,the continuous stamping stability can be strengthened by adding the air cooling or water cooling in the dies,improving the lubrication between dies and blank,and reducing the frequency of stamping.