초록 ▼

An improved injection molding system having gas injected through an injection pin associated with an ejector pin. The injection pin is movable between a retracted position at which it is sealed from the mold cavity, to an extended position where it delivers gas into the cavity. In a first embodiment

An improved injection molding system having gas injected through an injection pin associated with an ejector pin. The injection pin is movable between a retracted position at which it is sealed from the mold cavity, to an extended position where it delivers gas into the cavity. In a first embodiment, the injection pin is powered by a cylinder to move between the extended and retracted positions. In a second embodiment, the injection pin is actuated by the pressurized gas. The improved system injects gas into a mold cavity without the requirement of a separate injection aperture. Further, the inventive injection pins have outlet ports sealed from the flow of plastic until the injection pin is extended to deliver the gas.

대표청구항 ▼

An injection molding apparatus comprising: a mold body defining a cavity at an inner periphery for forming a part; an aperture for delivering fluent plastic into said cavity, said aperture adapted to be connected to a source of fluent plastic; a source of pressurized gas selectively communicating wi

An injection molding apparatus comprising: a mold body defining a cavity at an inner periphery for forming a part; an aperture for delivering fluent plastic into said cavity, said aperture adapted to be connected to a source of fluent plastic; a source of pressurized gas selectively communicating with said cavity through a passage in an injection pin, said injection pin being movable between an extended position where said passage communicates with said cavity to a retracted position where said passage does not communicate with said cavity, said injection pin being received within a bore defined by a cylinder inner wall, said passage having an outlet abutting said inner wall when in said retracted position to block communication between said outlet and said cavity; and said injection pin being moved between said extended and retracted position by a force from said gas delivered to said cavity, wherein said injection pin has a first end removed from said cavity and a second end selectively extended into said cavity, said first end acted upon by said gas to move said injection pin to said extended position, a piston face defined on said injection pin at an intermediate position between said first end and said second end, said piston face being acted upon by said gas to apply a force tending to move said injection pin to said retracted position, said piston face having a smaller surface area than said first end of said injection pin such that the force from said gas being applied to said first end overcomes the force of said gas applied to said piston face and said injection pin is forced to said extended position.