Injection unit for injection molding machines with continuously operating plasticizing unit
AssigneeKrauss-Maffei Kunststofftechnik GmbH
InventorRainer Zimmet
Life of this patent
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Abstract
An injection unit for an injection molding machine includes a plasticizing unit in the form of an extruder, a plunger-type injection device, which can be connected to the injection molding machine by an injection nozzle. The plunger-type injection device defines an injection space. The extruder has a forward portion which is connected to the injection space by a melt through channel in which a shutoff valve is disposed. The extruder is operated continuously and includes one or more plasticizing screws, wherein the extruder is configured in such a way that the backup length can expand backwards into the extruder, when the shutoff valve is closed.
Claims14
A combined plasticizing and injection unit for an injection molding machine, comprising:
- a housing;
- an injection nozzle supported by the housing for interaction with an injection mold;
- an extruder constructed for continuously producing melt and for forcing melt into the injection mold via the injection nozzle, said extruder including an injection plunger supported for movement in a telescopic manner in the housing and defining with the housing anteriorly of the injection plunger an injection space for supply of melt to the injection nozzle, said injection plunger configured to define a barrel and including a melt through channel for feeding the injection space with melt, said extruder including at least one plasticizing screw which is received in the barrel and continuously produces melt and which has an outer thread, and;
- a valve disposed in the melt through channel and controllable to close the melt through channel
- wherein the extruder has a passageway to enable melt to backup towards the rear via the outer thread of the plasticizing screw, when the melt through channel is closed by the valve and melt is injected into the injection mold by the injection plunger of the extruder.
A combined plasticizing and injection unit for an injection molding machine, comprising:
- a housing;
- an injection nozzle supported by the housing for interaction with an injection mold;
- a twin screw extruder constructed for continuously producing melt and for forcing melt into the injection mold via the injection nozzle, said extruder including an injection plunger supported for movement in a telescopic manner in the housing and defining with the housing anteriorly of the injection plunger an injection space for supply of melt to the injection nozzle, said injection plunger configured to define a barrel and including a melt through channel for feeding the injection space with melt, said extruder including two plasticizing screws which are received in the barrel and continuously rotate in a same direction for constantly producing melt;
- and
- a valve disposed in the melt through channel and controllable to close the melt through channel
- wherein the extruder defines a passageway between the two plasticizing screws to enable melt to backup towards the rear of the plasticizing screw, when the melt through channel is closed by the valve and melt is injected into the injection mold by the injection plunger of the extruder.
Dependencies are inferred from the claim text.