| 摘要 |
PURPOSE:To easily manufacture a strong performed body with no chipping at low cost by a method wherein an elastic body is employed at the bottom part, in which convexities are formed, of the preformed body. CONSTITUTION:Firstly, raw material is charged after an upper punch 3 is drawn out. At this time, much raw material flows in concavities 2, because the concavities are designed larger in consideration of the compressibility of material and final dimensions of a preformed body. Secondly, after the raw material is packed uniformly, the upper punch 3 is set in order to apply pressure to the raw material. The raw material is compressed and a bottom elastic body 1 is also compressed so as to reduce its height as the pressure is increased. Consequently, the raw material flowed in the concavities 2 is compressed vertically. The vertical compression of the bottom elastic body 1 results in the contraction of the bottom elastic body in the diametral direction. As a result, the raw material in the concavities is compressed both in the direction of height and in the radial direction so as to be tightly shaped. Finally, when the applied pressure is removed, the shape of the bottom elastic body 1 is restored to its initial condition and clearance is developed between the shaped leg part and the concavity of the elastic body and consequently the leg part can be prevented from chipping at some part when the preformed body is taken out of a mold.
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