PURPOSE: To eliminate the need for installing the rounding part of a punch device for forging and to obtain a forging having high rigidity by subjecting a tentatively sintered blank material to cold forging, then coating a sintering accelerator to a part in the angle parts of this forging and in succession, by subjecting this molding again to sintering and molding, thereby forming round at the prescribed positions.
CONSTITUTION: The tentatively sintered blank material 4 is mounted in the space part between upper, lower punches 2, 3 and a die 1 and is cold forged to form the forging 5. The angle parts 5a of the forging 5 in contact with the boundary part of the punches 2, 3 and the die 1 are formed as sharp edges. The sintering accelerator 7 in the form of the slurry formed by adding alcohol to Fe3P powder, etc., is coated by a suitable means to the above-mentioned edge parts of the angle parts 5a and the peripheral parts thereof and the forging is sintered at the temp. higher than the liquid phase generating temp. of the accelerator 7 to generate the liquid phase and to accelerate the sintering by which the round 5b is formed to the coated parts. The round 5b is thereby formed to the prescribed positions of the forging 5 and the sharp edges are eliminated.
MORIMOTO SHIGENORI
YAMANE MAKOTO
