| 摘要 |
PURPOSE:To prepare a light wt. double pipe having a strong structure in an extremely efficient and certain manner, by forming a double pipe having a hermetically sealed hollow barrel part between the inner and outer pipes thereof by blow molding. CONSTITUTION:Both molds 5A, 5B approach to each other and matched so as to hold an inner pipe 1 and a parison 4 therebetween to perform clamping. Because the parison 4 is held under a molten state at a high temp. (180-200 deg.C), a sharp contact parts 5a of the molds are contacted with the parison 4 to divide the same into a parison part 4B used in forming an outer pipe and an unused parison part 4A. Therefore, the parison part 4B is integrated with the protruded part 1a of the inner pipe 1 and allowed to fill the grooves 1b, 1b' of the inner pipe 1 to perform the positional determination of the connection part of the inner and outer pipes. After clamping, compressed air is introduced into the inner pipe 1 and the parison part 4B is expanded in the mold hole through the through-hole 1d of the pipe and pressed to the surface of the mold hole to form a hollow barrel part E. |
