| 摘要 |
PURPOSE:To enable simple and efficient production of a double cylindrical product even if a molten metal of poor fluidity is used by vacuum sucking the prescribed molten metal into a metallic cylindrical member and ceasing the suction after holding the same for a prescribed time. CONSTITUTION:A mild steel pipe 10 is attached by means of a clamp 16 to a support base 14 of an induction furnace 12, and is preheated in an Ar atmosphere, thereafter the open port at the bottom end of the pipe 10 is dipped in, for example, a molten Ni alloy 18 in the furnace 12. The pipe 10 is evacuated via a suction pipe 20 through the open part at the top end of the pipe 10 and the pipe 10 is pulled up from the molten alloy 18 upon lapse of a prescribed time. Then, the solidified metal 26 positioned in the central part of the pipe 10 escapes by flowing downward and a solidified layer 28 consisting of the Ni alloy is formed on the inside surface of the pipe 10, thereby obtaining a double cylindrical product of which the outside cylindrical part corresponds to the pipe 10. |
