An Upper Bound Analysis of the Shapes of the Dead Metal Zone and the Curving Velocity Distribution in Eccentric Plane Dies Extrusion

평다이를 사용한 편심 압출가공에서의 비유동 영역의 형상과 굽힘 속도 분포에 관한 상계해석

The kinematically admissible veolcity field is developed for the shapes of dead metal zone and the curving velocity distribution in the eccentric plane dies extrusion. The shape of dead metal zone is defined as the boundary surface with the maximum friction constant between the deformable zone and the rigid zone. The curving phenomenon in the eccentric lane dies is caused by the eccentricity of plane dies. The axial velocity distribution in the plane dies is divided in to the uniform velocity and the deviated velocity. The deviated velocity is linearly changed with the distance from the center of cross-section of the workpiece. The results show that the curvature of products and the shapes of the dead metal one are determined by the minimization of the plastic work and that the curvature of the extruded products increase with the eccentricity.