相对弯曲半径对成形凹模接触应力峰值的影响

Influence of relative bending radius on contact stress peak of forming die

动态接触应力尤其接触应力峰值是造成高强钢成形凹模局部磨损的主要原因,相对弯曲半径是影响接触应力峰值的最大因素。通过宽板弯曲成形圆角受力分析,得到相对弯曲半径与板料厚向主应力关系式,定性分析相对弯曲半径与凹模圆角接触应力的负相关性。利用U形件弯曲有限元模型,获得系列相对弯曲半径对应的接触应力峰值曲线,分析峰值曲线特征及变化趋势。经拟合分析得到最大接触应力峰值与相对弯曲半径的二阶多项式关系,可为接触应力峰值预测、模具选材提供指导。

The dynamic contact stress especially the peak of contact stress is the main reason for the regional wear of high strength steel forming die. The most important factor that influences the peak of contact stress is the relative bending radius. By the stress analysis of wide sheet bending forming, the relation of relative bending radius and the principal stress at the direction of plate thickness was obtained. Qualitative analysis of the negative correlation between relative bending radius and contact stress of die fillet was carried out. With the finite element model of U-shaped bending, a series of relative bending radii corresponding to the peak contact stress curves were obtained and the peak curve characteristics and trend were analyzed. Through the fitting analysis, the second order polynomial relations of the maximum contact stress peak value and the relative bending radius were fitted. The equation can help engineers to predict the peaks of contact stress and to choose mold material.