大锻件空洞的局部效应与锻合压下率研究

为了在锻造过程中消除锻件内部的空洞型缺陷,采用热力耦合有限元法模拟了各种条件下圆柱体锻件中心空洞的热锻闭合过程。研究结果表明,空洞的闭合是局部变形问题,其主要影响因素是锻件的高径比、空洞形状和摩擦条件。将数值模拟结果进行拟合处理,得到了便于应用的空洞闭合临界压下率的计算公式。该公式的预报结果和有限元模拟结果吻合良好,因而在一定程度上反映了各主要因素对空洞闭合的影响。根据数值模拟结果和拟合公式总结了空洞闭合的规律。

A STUDY OF LOCAL EFFECTS OF PORE AND CRITICAL REDUCTION FOR PORE CLOSURE IN HEAVY INGOTS

To eliminate the pore defects in ingot by hot forging process, the closure of pores in solid cylinders undergoing hot forging is numerically simulated by thermomechanical coupling finite element method. The results show that the closure of pore relies on the local deformation, and the main influencing factors are the ratio of ingot height to diameter, pore shape and friction. An empirical formula, which can be easily used to calculate the critical reduction for closing the center pore, is obtained by regression on the numerical results. The predictions of the empirical formula are in good agreement with those of finite element solution, which indicates that the formula can represent, to some extent, the effects of the main factors on the pore closure. Some principles for pore closure are summarized according to the numerical results and the formula.