| 摘要 |
PURPOSE: To obtain powder compacts of theoretical density with high cycle frequencies by applying electric current pulses to a metal powder in a pressurized state, at the time of filling a mold with a metal powder and forming it into a compacted component by static pressing. CONSTITUTION: A mold, having a side wall composed of a non-electrical conductive material, is filled with electrical conductive powder or preliminarily pressed powder and then pressed. At this time, 1 to 3 electric current pulses of from 5×10<-5> to 5×10<-3> S duration, >=20 As electric charge per cm<3> of the material to be pressed, and <=30 V voltage between the upper and lower rams are applied while applying an axial compacting pressure not higher than the ordinary value by means of static pressing. By this procedure, abrupt contraction in volume and powder compaction are provided to the material to be pressed in a pressurized state, by which compression density greater than 96% of theoretical density can be achieved. Further, machine springs, or the like, are attached to a press for the above pressing to make it possible to make the abrupt contraction in volume, occurring in the material to be pressed and to follow the raising/ lowering direction of the press ram without delay. |
