초록 ▼

A method and apparatus for runnerless injection molding of plastic materials utilizing a novel valve stem for controlling the opening and closing of at least two gates in a single injection nozzle. The method and apparatus includes at least two separate melt streams whose flows are not obstructed by

A method and apparatus for runnerless injection molding of plastic materials utilizing a novel valve stem for controlling the opening and closing of at least two gates in a single injection nozzle. The method and apparatus includes at least two separate melt streams whose flows are not obstructed by the valve stem. These melt streams may contain the same plastic material or different plastic materials and the injection nozzle may be either simultaneously or sequentially activated for filling the mold cavity.

대표청구항 ▼

[ I claim:] [1.] A method of co-injecting at least two different plastic materials to form a multi-layer molded product using a hot runner injection molding machine with a separate channel for each material, each channel having an end in communication with an injection nozzle with a corresponding se

[ I claim:] [1.] A method of co-injecting at least two different plastic materials to form a multi-layer molded product using a hot runner injection molding machine with a separate channel for each material, each channel having an end in communication with an injection nozzle with a corresponding separate gate for feeding an injection mold and flow between said separate gates being prevented by a gate separating means, the method comprising for each of said at least two plastic materials(i) heating said plastic material in the respective separate channel;(ii) moving a valve stem to a position wherein said corresponding gate for said plastic material is open;(iii) inject a selected amount of said plastic material from said respective channel through said corresponding gate in said nozzle into the injection mold and preventing further flow of said plastic material from said corresponding gate;(iv) moving said valve stem to close said corresponding gate.