초록 ▼

An improved gating needle for use in an injection molding sprue bushing has an elongated central needle portion and at least three radially extending members which extend radially outwardly from the central needle portion. The gating needle is seated in an annular cavity or circular recess disposed

An improved gating needle for use in an injection molding sprue bushing has an elongated central needle portion and at least three radially extending members which extend radially outwardly from the central needle portion. The gating needle is seated in an annular cavity or circular recess disposed at the outlet end of a sprue bushing and is capable of slight axial movement due to the action of the injected melt flowing around it so that the needle maintains a constant position and clearance within the mold cavity gate. The gating needle may include an interior heat transfer portion in the form of either a highly thermally conductive metal core portion or in the form of a sealed hollow tube containing a vaporizable liquid, which interior portion transfers heat from the surrounding melt to the mold cavity gate to maintain the mold cavity gate area at a constant temperature.

대표청구항 ▼

An internally heated sprue bushing assembly having an inlet for receiving pressurized melt and an outlet for discharge of the pressurized melt, the sprue bushing assembly comprising a unitary bushing casing-core element having an elongated outer sidewall, an end wall and an elongated inner core inte

An internally heated sprue bushing assembly having an inlet for receiving pressurized melt and an outlet for discharge of the pressurized melt, the sprue bushing assembly comprising a unitary bushing casing-core element having an elongated outer sidewall, an end wall and an elongated inner core integrally formed together, an outer surface of the elongated inner core and an inner surface of said sidewall defining a generally annular compartment within said bushing casing-core element, heating means for heating said elongated inner core, the heating means being disposed in surrounding relation to said elongated inner core, said heating means axially extending a preselected length within and occupying a portion of the annular compartment, a compacted unified mass of particulate material occupying the remainder of said annular compartment, a melt runner passage disposed in said elongated inner core interposed between and in melt flow communication with said inlet and outlet of said sprue bushing assembly, and a gating needle, said sprue bushing outlet including a recess formed therein, the recess being adapted to slidingly receive the gating needle within an inner sidewall thereof, said gating needle including an elongated body having a first end portion, a second end portion and an intermediate portion disposed between said first and second end portions, the intermediate portion including a plurality of radially extending support members, each support member having a first engagement surface being adapted to slidingly engage the outlet recess inner sidewall, a second engagement surface adapted to seatingly engage an interior rim of said outlet recess and a third engagement surface which is adapted to abuttingly engage an opposing surface of a mold cavity plate, the gating needle first end portion projecting forwardly of said intermediate portion and said first engagement surfaces thereof, the gating needle second end portion projecting rearwardly of said intermediate portion and said third engagement surfaces thereof into said melt runner passage for a selected length, said gating needle first end portion having a generally conical tip, the gating needle elongated body including an interior portion having means for transferring heat from said needle second end portion to said needle first end portion, said gating needle being movable along a longitudinal axis within said sprue bushing outlet recess between a first operational position wherein said gating needle intermediate portion first engagement surfaces are in contact with said sprue bushing outlet recess interior rim and a second operational position wherein said gating needle intermediate portion third engagement surfaces are in contact with an opposing surface of a mold cavity plate.