Injection unit for injection molding machines with continuously operating plasticizing unit
AssigneeKrauss-Maffei Kunststofftechnik GmbH
InventorRainer Zimmet
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Abstract
An injection unit for injection molding machines includes an extruder as plasticizing unit and a plunger-type injection molding device that can be coupled to the injection molding machine by an injection nozzle. The plunger-type injection molding machine has an injection plunger, wherein the area in front of the injection plunger forms an injection space which is connected to a forward end of the extruder by a melt channel, with a shutoff valve disposed in the melt channel. The extruder can be continuously operated and has one or more plasticizing screws for plastification, wherein the extruder is so configured that a backup length is able to increase backwards into the extruder, when the shutoff valve is closed.
Claims10
An injection unit for an injection molding machine, comprising:
- a plasticizing unit in the form of a continuously operated extruder having a forward end and including at least one plasticizing screw;
- a plunger-type injection device including an injection nozzle for interaction with an injection mold, and an injection plunger demarcating anteriorly thereof an injection space which is connected to the forward end of the extruder by a melt channel;
- and
- a shutoff valve disposed in the melt channel,
- wherein the extruder is so configured that a backup length is able to expand backwards into the extruder, when the shutoff valve is closed.
A method for operating an injection molding machine of a type having an injection plunger for pushing melt from an injection space anteriorly of an injection plunger into an injection mold, comprising the steps of continuously operating a plasticizing screw of an extruder to feed melt through a melt channel into the injection space;
- and closing passage through the melt channel to allow backup of melt backwards into the extruder.
Dependencies are inferred from the claim text.