| 摘要 |
PROBLEM TO BE SOLVED: To provide a green compact with stable weight from the beginning by heating a die to take part in forming a die cavity during its operation, preheating it to the balanced temperature, adjusting the filling quantity of a raw material powder in this condition to a specified value, and starting the continuous forming to eliminate the fluctuation in weight of the green compact generated in the initial stage. SOLUTION: A raw material powder is filled in a die cavity, and compressed between upper and lower punches 30, 20, and the obtained green compact is pushed out of a die 10 by the lower punch 20. The balanced temperature of the die during the operation is affected by various conditions such as the kind of the powder, the shape and dimensions of the green compact, the forming pressure and the forming speed, the material and surface roughness of the die, but in most cases, it is dependent on the die temperature before starting the forming. The die 10, a core rod 40 and the lower punch which are to be preheated is preheated in the range of 10-30 deg.C higher than the die temperature before the forming is started. Electrically heated hot air is preferably blown as a preheating means.
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