Method for controlling the injection process and injector unit
AssigneeNetstal-Maschinen AG
InventorAndreas Lind
Life of this patent
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Abstract
The invention relates to an injector unit and a method for the control of the injection process into the cavities of injection moulding tools. The novel solution permits the injection of thin-walled injection moulding pieces (76, 77), with both electrically- and hydraulically-driven injector screws. One of the most important features thereof is the active selection of the opening time of the locking system at an optimal pressure in the compression chamber, preferably in the region of the upper half of the compression. The volumetric transfer flow is thus significantly improved in thin-walled injection moulding pieces (76, 77). Above all the melting pressure in the tool, the flow speed and the useful flow path in the cavities are increased.
Claims20
A method for controlling an injection stroke and a compression stroke of an electrically or hydraulically driven injection screw of an injection mold, the injection screw being provided in a chamber, the injection mold being for production to form a thin-walled injection molded articles including a material, the injection mold having a cavity, and an active closure provided between the chamber and the cavity, wherein a transition from compression of a melt to a volume transfer flow is established, the method comprising the steps of:
- developing the compression stroke into the injection stroke without interruption;
- and
- rapidly opening the active closure in a controlled manner at a desired pressure in the chamber or at a desired compression of the melt within the chamber,
- wherein a velocity of the injection screw remains substantially unchanged during the opening of the active closure.
An injection unit for injection of a material to form a thin-walled injection molded article, in an injection mold, the injection mold having an electronically or hydraulically driven injection screw and a nozzle opening provided between the injection screw and a mold cavity, and the injection mold including a controllable active closure for the nozzle opening, the injection unit comprising:
- control means for controlling a two-step, uninterrupted linear movement from a compression stroke to an injection stroke of the injection screw, the active closure being operated between the compression stroke and the injection stroke;
- and
- electric or hydraulic drive means for suddenly opening the active closure,
- wherein a velocity of the injection screw remains substantially unchanged during the opening of the active closure.
Dependencies are inferred from the claim text.