| 摘要 |
PURPOSE:To form a bent pipe which its thickness is impartial and has a uniform surface by a method wherein the bent pipe is clamped by molds while pressure air is blown off from small holes formed to an inner surface of the metal mold first contacting with a parison when the pipe is clamped by the molds, and the pipe is blow-molded. CONSTITUTION:When a bent pipe is clamped by molds, a large number of small holes 11 with approximate 0.1-0.3mm. diameters are previously formed to a central convex portion 10 of a metal mold 1 first contacting with a parison. The parison is vertically extruded to an intermediate portion between metal molds 1, 2 under opening conditions, the metal molds 1, 2 are moved toward the parison while pressure air is blown against the parison from the small holes 11 through passages 12 in the metal mold 1, and the metal molds 1, 2 are completely closed at a uniting surface 3 while preventing contact between the parison and the metal mold 1. The bent pipe is molded by blowing air into the parison while removing air from the small holes 11, cooling water is passed through holes 13 in the metal mold, the pipe is cooled, the metal molds are opened, and the bent pipe as a product is extracted. |
