Abstract: A two-stage, electrically-powered injection unit for an injection molding machine includes an extruder for plasticating material, and a separate melt accumulator to receive the plasticated material. The accumulator includes an injection plunger that is slidably positioned to inject the plasticated material from the accumulator into a mold. The plunger is rotated and translated by an electrically-driven linear actuator, such as a roller screw mechanism. The plunger extends outwardly of the accumulator barrel at the commencement of an injection stroke and is peripherally supported by a bushing at the outer end of the accumulator barrel. The outwardly-extending portion of the plunger can also be supported by a movable intermediate support member to minimize lateral deflection of the plunger and enable a longer injection stroke to be employed.

Abstract: A two-stage, electrically-powered injection unit for an injection molding machine includes an extruder for plasticating material, and a separate melt accumulator to receive the plasticated material. The accumulator includes an injection plunger that is slidably positioned to inject the plasticated material from the accumulator into a mold. The plunger is rotated and translated by an electrically-driven linear actuator, such as a roller screw mechanism. The plunger extends outwardly of the accumulator barrel at the commencement of an injection stroke and is peripherally supported by a bushing at the outer end of the accumulator barrel. The outwardly-extending portion of the plunger can also be supported by a movable intermediate support member to minimize lateral deflection of the plunger and enable a longer injection stroke to be employed.

Abstract: A two-stage, electrically-powered injection unit for an injection molding machine is disclosed. The injection unit includes an extruder for plasticating material, and a separate melt accumulator to receive the plasticated material. The accumulator includes an injection plunger that is slidably positioned to inject the plasticated material from the accumulator into a mold. The plunger is rotated and translated by an electrically-driven linear actuator, such as a roller screw mechanism. The plunger extends outwardly of the accumulator barrel at the commencement of an injection stroke and is peripherally supported by a bushing at the outer end of the accumulator barrel. The outwardly-extending portion of the plunger can also be supported by a movable intermediate support member to minimize lateral deflection of the plunger and enable a longer injection stroke to be employed.

Abstract: A nozzle shut-off valve for the plastication system of an injection molding machine. The valve includes a cylindrical body member that has axially spaced inlet and outlet passageways. Inclined passageways that extend from the inlet and outlet passageways to the outer surface of the body member to terminate in spaced openings on the periphery of the inner body member. A tubular outer member is provided with at least one recess or depression on its inner surface, the recess having a length sufficient to provide communication between a pair of the spaced peripheral openings in the inner body member when the recess is positioned in overlying relationship with the respective openings. Rotation or translation of the tubular outer member relative to the inner body member shifts the recess out of registration with the respective peripheral openings, to thereby prevent flow of material through the valve.