| 摘要 |
PROBLEM TO BE SOLVED: To avoid generation of partial breakage of a formed body by applying the organic substance of low softening point to a surface of a core rod in contact with the filled powder to easily pull out the core rod. SOLUTION: A rubber die of double cylinder comprising an outer cylinder of the prescribed diameter and an inner cylinder coaxial with the axis in the direction of its depth (longitudinal direction) and smaller in diameter than the outer cylinder, which is thin-walled, high in expansion strength and formed of latex rubber is used. A hollow core rod consisting of a high strength material and approximately same in diameter is inserted in the cylindrical die, and the high-speed steel powder containing molybdenum carbide and vanadium carbide is tightly filled in a space between the outer and inner cylinders of the rubber die. The organic substance of low softening point such as paraffin wax is applied to the surface of the hollow core rod by 0.1-5 mm in thickness. After filling the powder, hot water is poured into the hollow core rod to keep the organic substance of low softening point on the outer surface in the molten condition, and then, the core rod is pulled out. A formed body having a hollow part can be manufactured with excellent yield. |
