高强钢弯曲凹模型面接触应力分布及演化

Research on the distribution and evolution of contact stress on the bending die surface in the forming process of the high strength steel

材料成形过程中,模具型面磨损分析的关键是获得接触应力的分布及演化特点。利用高强钢U形件弯曲模型得到模具型面接触应力解析式。通过准静态有限元仿真分析,获得了弯曲凹模圆角型面瞬态→稳态的接触应力演化趋势及单-双峰分布特征。瞬态区接触应力峰值波动剧烈呈现尖锐的双峰分布;稳态区平缓趋于直线。对比分析高强钢DP600与低强度钢DC04的接触应力峰值曲线,揭示了高强钢成形模具型面局部磨损的主要原因,并通过实例验证了其合理性,为提高模具寿命提供了途径。

In forming process ,the key issue forwear analysisat the contact surface between the die and blank is to obtain thedistri-bution and evolutionofcontact stress.The analytic expression of the contact stress is deduced through the U-shape stamping part of high strength steel. The evolution trend and the single-bimodal distribution characteristics from the transient state to the steady state are acquired on the fillet surface of die ,which is followed by FEM modeling and numerical simulation. The investigation shows that the curve of the contact stress in the transient zone fluctuatesdrasticallyand it shows bimodal distribution ,and the curve of the steady zone is smooth as a straight line. Research result reveals the main reasons for the wear ,through comparison a-nalysis the curves of contact stress peak between DP600 and DC04.Through observation on factory experiments ,the rationality of the estimation was verified ,it provides a way to improve the life of die .