| 摘要 |
PURPOSE:To make it possible to obtain a parison with uniform thickness by a method wherein the gap of a slit along the peripheral surface of a tip mandrel is minutely controlled by vertically moving a rod, which runs from the packing box of a parison cylinder above a mandrel and pierces through the central mandrel of a lower die and to which the tip mandrel is screwed. CONSTITUTION:At the upper part of a profile die A, a parison cylinder 1, at the center of a packing box 3 of which a rod 4 is hung down so as to pass through the center of a lower mandrel 5 to be screwed 4' to a tip mandrel 6, is provided. The annular art of a ram, which is internally installed in an injection cylinder 2, injects the filler material of an accumulator 9 just below the ram to a lower slit 15 as an injection plunger 10 so as to form a parison 14. In this case, the slit 15 is actuated integrally with the injection plunger in about 40 steps by vertically moving the tip mandrel through the application of hydraulic pressures to an upper space 1a and a lower space 1b. Thus, the drawdown of the parison 14 is prevented from developing and consequently a blow molded item with uniform thickness is efficiently formed. |
