| 摘要 |
PURPOSE:To stably form skin layer and at the same time mold a conforming molded item with no flow mark by a method wherein the flow rates of molten synthetic resins, which are injected respectively through an outside passage and an inside passage for forming the skin layer and core layer, are controlled by reciprocating only an inside torpedo so as to adjust the moving position of the inside torpedo to the predetermined intermediate position. CONSTITUTION:A control device 28b brings a screw reciprocatingly driving device 27b into actuation so as to advance a second screw 21 to the most advanced position in order to force molten synthetic resin for forming core layer in an inside passage 13. As a result, a part of the molten synthetic resin for forming the skin layer is injected in a cavity 37d, which is formed between both molds 37a and 37b. Concretely, molten synthetic resins, which flow respectively through both passages 12 and 13, flow in a nozzle hole 6a in the laminar flow, in which the core layer is completely covered by the skin layer, and is injected in the cavity 37d, which is formed between both the molds 37a and 37b. Further, by automatically moving the inside torpedo 8 to the predetermined intermediate position in order to hold it to that position, the flow rates of the molten synthetic resins, which flow through both the passages 12 and 13 respectively in the nozzle hole 6a, are controlled so as to allow to stably form the skin layer. |
