곡면 형상을 가진 금형에 의한 축대칭 냉간 단조의 유한 요소 해석

Abstract

The paper is concerned with the analysis of spike forging and backward extrusion as nonsteady processes by the rigid-plastic finite element method. These process include die boundaries of curved shape and this should be taken into account in the finite element formulation. The spike forging process is characterized by large free surface, rigid part and curved contact surface. The developed program for initial velocity field generation is included in the present FEM program. The workhardening effect, rigid body treatment and interface friction along curved die surface are introduced in the formulation. In backward extrusion deformation is very severe around the punch corner and the remeshing technique is employed in the FEM program to combat this problem.The experiments are carried out for spike forging and backward extrusion with commercially pure aluminum(Al 1100) billets. Computational results in deformation and load are in excellent agreement with the experimental observation. The present analysis permits the prediction of stresses, strains and strain rates. The effects of fiction factors on interface pressure and spike height are discussed in spike forging. It is thus shown that the present formulation enables the effective design of axisymmetric cold forging processes.