抄録
Combined extrusion forging is not used widely. The reason seems that it is impossible to predict the load and extruded length easily. It is considered that the extrusion load and extruded length are affected by the shape ratio of the billet (initial billet height (ho)⁄initial billet diameter (do)). In this study, the effect of the shape ratio of the billet on the extruded length was examined experimentally and by finite element simulation. The extruded length is affected by the shape ratio of the billet. In the case of a shape ratio of 1.5, the deformation is of the separate flow type. In the case of a shape ratio of 0.4, the deformation is of the shear flow type. The ratio of the forward extruded length to the backward extruded length (Lb'⁄Lf) decreases with an increase in the ratio of the reduction in area (Rb⁄Rf). Moreover, in the billet with a large height compared with the diameter, the relationship between extruded length and stroke changed in a certain stroke. When the diameter and height of the billet were decided on the basis of the size of the product, the method predicted both the forward and backward extruded lengths.
