超塑性材料的镦粗变形力的研究

Upsetting forming pressure study of superplastic materials

通过采用主应力法导出考虑纵向变形速度和横向加速度的镦粗变形力的计算公式,并用算例讨论了超塑性材料变形力的计算方法、变形力随时间的变化规律,以及纵向变形速度和横向加速度对变形力的影响大小。由于主应力方法适合于a/h不太小的情况,因此导出的公式也应该满足这一条件。变形力可以分成qj,qy,qd3项,其中qd在ρV2/k极小于1时,可以忽略不计;但是当ρV2/k接近于1时就不可忽略。接触面的分布压力的最大和最小值的位置和一般率无关的塑性材料镦粗时的位置一样,分别在x=0和x=±a/2处。

The calculating formula of upsetting forming pressure considering longitudinal forming velocity and transverse aceeleration has been conducted by using main stress method in this paper. The calculating method, the relation between the forming pressure and time, and the affection of longitudinal forming velocity and transverse acceleration to the forming pressure are discussed through an example. Main stress method is suitable when a/h is not too small. Therefore, the formula obtained in this paper should be also a meet for this condition. The forming pressure is divided into three items： qj, qy, qd. qd is neglectful when ρV^2/k is far smaller than 1; qd is not neglectful when ρV^2/k is close to 1. The position of maxium and minimum distribution pressure is the same as that of common upsetting of velocity-independent plastic material. The maximurn pressure is at where x=0 and the minimum pressure is at where x=±α/2.