| 摘要 |
PURPOSE:To always accurately adjust a mixing ratio, at a time of the supply of a main resin and an auxiliary resin to an accumulator, by adjusting the flow-down amt. of the auxiliary resin by a flow rate adjusting ring while adjusting the flow-down amt. of the main resin on the basis of the resin extruding speed of a plunger. CONSTITUTION:When a multilayered parison 70 wherein the whole of a duct is composed of a soft resin (main resin) 13a having flexibility and a part of the duct is composed of a hard resin (auxiliary resin) 13b is formed, at first, the plunger 44a of a main resin accumulator 44 is allowed to advance and the molten main resin 13a is supplied to a resin introducing passage 48 and introduced into a land part 65 from the lower edge of a main resin manifold 47. The auxiliary resin 13b is introduced into a land part 66 from the lower edge of an auxiliary resin manifold 57 and both resins are extruded from a resin emitting port 28 to obtain the multilayered parison 70. At this time, the flow-down amt. of the auxiliary resin 13b is adjusted by the passage adjusting ring 23 freely displaced by a cylinder 25 and that of the main resin 13a is adjusted based on the resin extruding speed of the plunger 44a. |
