| 摘要 |
PURPOSE:A foamed resin is additionally filled in the cavity of mold and simultameously the evolving gas is made to flow out through fine gaps to form almost complete skin layer on the cut section of the molded product at the gate. CONSTITUTION:A thermoplastic resin containing a foaming agent is extruded from nozzle 1 in an injection molding machine through sprue 2, runner 3, and gate 4 into the cavity 5 of mold provided with channels for cooling water 6 to form skin layer 7 and foaming layer 8 by solidifying the resin under cooling. Then pin 10 is inserted again into gate hydraulic cylinder 11 through link 12 and at the same time a foaming gas is leaked through gap 15 provided between mold 16 and pin 10 while a resin containing no foam is additionally charged to gate 14. After the resin in cavity completely solidifies by cooling, the mold is opened and a foamed product having gate cut section 14 covered with skin layer. |
