外縁部の形状転写能を向上させた側方押出し鍛造
による軸付き円板成形加工

抄録

A disk with an axis, such as a flywheel, roller or knob, can be formed directly from a cylindrical workpiece by cold axisymmetric upsetting with lateral extrusion. A lack of material filling was observed at the rim of a product when an ordinal die was used. We carried out forming experiments by cold plane strain upsetting with lateral extrusion, and discovered that a stepwise cavity placed on the side end of the bottom plane in a die cavity generates an effective material flow to complete the lacking portion at the corner of the extruded part. We carried out further experiments to improve shape transferability at the rim by forming a disk with an axis from a cylindrical workpiece by cold axisymmetric upsetting with lateral extrusion. The punch loads and outer profiles of the workpiece were measured during the forming. Then, the optimum dimensions of the stepwise cavity that achieve superior shape transferability at the rim of the disk with a lower maximum forming load could be determined. When the concave side of the disk formed by the above die configuration corresponds to the design of a lightweight product, net shape forming can be achieved.