SPRING BACK PHENOMENON EXHIBITED IN THE PROCESS OF HOLLOW CYLINDER UPSETTING

Spring back of the end surfaces of the biller and the elastic deflecti on of the dies in the process of hollow cylinder upsetting between ela stic platens is investigated using a thermo-elastic-plastic coupling m odel. The finite-element method and the finite-difference method are a dopted to simulate the forming process, and the unloading process is p erformed on the elements of the workpiece ill response to the spring b ack phenomenon accounted for in this study. Therefore, the effect of d ie elasticity on the variation of the inner surface profile of the hol low cylinder predictions of forging load, and the distributions of tem perature and strain components may be examined. The surface asperity o f the biller and the forging load obtained by simulation agree quire w ell with the results of the upsetting experiment.