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US 4,942,006 AGranted
Method of and apparatus for injection molding with pressurized-fluid assist
AssigneeMichael Ladney
InventorNorman S. Loren
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AssigneeMichael Ladney
InventorNorman S. Loren
Estimating the term…
An injection molding method and nozzle for use therein wherein first and second variable pressures are applied to a piston of a valve mechanism of the nozzle so that a differential fluid pressure on the piston causes a tip portion of the valve mechanism to alternately open and close. In this way, the tip portion communicates the flow of resin from a nozzle body of the nozzle to an injection aperture of a mold. Differential pressure on the piston prevents a fluid which distributes the molten resin over the interior surfaces of the mold from entering the flow path of the molten resin in the nozzle body. The fluid preferably is a gas, such as nitrogen. Preferably, the piston is mounted for reciprocating movement within the nozzle body and the first pressure is provided by the resin during resin injection and the second pressure is partially applied by the nitrogen gas. Preferably, the valve mechanism includes a counterbalance mechanism which is set to prevent fluid entry into the mold until the tip portion of the valve mechanism is closed. The resulting article is then cooled to a temperature below the softening point of the resin, the pressure is relieved within the article and the mold is opened to remove the article. The nozzle may also be utilized in making structural foam articles from a foamable resin. The pressure within the mold is relieved to permit foaming by the foamable resin after injection of the foamable resin.
A method for making an article from at least one plastic resin having a softening point in an injection molding system including a pressurized fluid source, a mold having an injection aperture and interior surfaces, an injection nozzle having a nozzle body for establishing a flow path or molten resin through the injection aperture and valve means including a piston and a tip portion operatively associated with the piston to move therewith, the tip portion having a closed position and an open position to communicate the flow of plastic resin from the nozzle body through the injection aperture, the method including the steps of:
A nozzle for use in a fluidassisted injection molding system including a pressurized fluid source, a mold having an injection aperture and an injection molding machine, the nozzle including a nozzle body having means for establishing a flow path for molten resin, a first end of the nozzle body being adapted for resin connection with the mold and a second end thereof being adapted for resin connection with an end of the injection molding machine;
A method for making a structural foam article from a foamable resin having a softening point in an injection molding system including a pressurized fluid source, a mold having interior surfaces and an injection nozzle having a nozzle body for establishing a flow path for molten resin and a valve means having a piston and a tip portion operatively associated with the piston to move therewith, the method comprising the steps of:
Dependencies are inferred from the claim text.