초록 ▼

A gas injector having a retractable nozzle with linear gas feed passage therethrough for a gas assist plastics injection molding machine. The injector interfaces with the injection molding tool and has a nozzle with a tip that, in a forward position, protrudes through a port therein leading into the

A gas injector having a retractable nozzle with linear gas feed passage therethrough for a gas assist plastics injection molding machine. The injector interfaces with the injection molding tool and has a nozzle with a tip that, in a forward position, protrudes through a port therein leading into the tool cavity or a runner system leading into the cavity for gas injection during molding. The nozzle tip is connected by a nozzle body to a base that is operatively mounted in an actuator housing. The base is connected to an in-line gas routing extension of the nozzle that projects through the outer cover of the housing. The extension is coaxial with an internal spring that seats on the base and holds the nozzle tip in a gas injection position resisting the force of plastics injection pressure. The base connected nozzle is retracted by combined flux fields of an electromagnet and a permanent magnet mounted within the housing while compressively loading the spring enhancing gas release from the cavity tool separation and subsequent ejection of molded part. The electromagnet is then deenergized since the permanent magnet has a sufficient magnetic force field to, hold the base and the attached nozzle in the retracted position. For return to the gas injection position, the electromagnet is again energized but with the current supplied thereto reversed so flux field of the electromagnet is reversed to negate flux field of the permanent magnet allowing the spring to return the nozzle to the forward position.

대표청구항 ▼

A gas injector for feeding pressurized gas to assist the plastics injection molding of a part in a cavity of a mold in which heated viscous plastics material is supplied thereto, the pressurized gas forcing the plastics material into a hollow molded part conforming to the contours of the cavity of t

A gas injector for feeding pressurized gas to assist the plastics injection molding of a part in a cavity of a mold in which heated viscous plastics material is supplied thereto, the pressurized gas forcing the plastics material into a hollow molded part conforming to the contours of the cavity of the mold, said mold having an opening therein leading from an outer surface thereof to the cavity therein for receiving at least part of said gas injector, said mold having a seat surface defining a portion of said opening, said injector comprising a housing having an inner end wall adapted to be secured in a fixed position on said mold and having a side wall extending from said end wall and having an outer end cap to define a chamber, said gas injector having base means mounted for linear movement between first and second positions in said chamber, an elongated gas injector nozzle body affixed for movement with said base means and extending through an opening in the inner end wall, into the opening in said mold, and toward said cavity, said nozzle body terminating in a nozzle attachment end, a gas delivery nozzle having an exterior surface, said gas delivery nozzle secured to said attachment end of said nozzle body and movable therewith between a gas injection position wherein said exterior surface mates with said seat surface when said base means is in said first position for feeding pressurized gas into said cavity and a gas exhaust position away from said cavity wherein said exterior surface is spaced from said seat surface to establish a gas exhaust passage extending around the exterior surface of said nozzle and through the opening in said mold to exhaust gas from said cavity when said base means is in said second position, spring means of a first height operatively mounted in said housing for forcing said base means into said first position and magnetic means mounted within said housing, said magnetic means including a permanent magnet and electrically energizable coil means selectively energizable with electrical current flow therethrough in a first direction to produce a magnetic force field which combines with a magnetic force field of the permanent magnet to move said base means from said first position to said second position to compressively load and deflect said spring means to a second height less than said first height while moving said nozzle from said gas injection position to said gas exhaust position in which gas is exhausted from said cavity through said gas exhaust passage, and internal gas feed passage means extending through said housing and said base means and said nozzle body and said nozzle for feeding a pressure gas into said mold through said gas delivery nozzle when in said gas injection position, said coil means being further selectively energizable with electrical current flow therethrough in a second direction opposite to said first direction to produce a magnetic force field to negate the magnetic force field of said permanent magnet so that said spring means recovers to said first height to move said nozzle to said gas injection position.