Needle assembly for gas-assisted injection moulding
AssigneeUniversity of Warwick
InventorsGordon Frederick Smith, Rui Magalhaes
Life of this patent
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Abstract
A fluid injection and exhaust needle for use in gas injection moulding comprising a needle with two separate flow channels; a fluid inlet channel and a fluid outlet channel; wherein gas is injected into the melt via the fluid inlet channel to form a gas cavity in the melt, and gas is simultaneously exhausted from the cavity via the fluid outlet channel.
Claims13
A gas injection and exhaust needle assembly for injecting a gas into a liquid melt during gas injection moulding comprising at least a gas inlet channel and a separate gas outlet channel and means for allowing the simultaneous entry and exit of gas to the respective channels,
- wherein at least one of said channels comprises a flow restrictor sized such that in use gas may freely flow through the channel but liquid moulding material may not freely flow therethrough,
- wherein the flow restrictor further comprises a strip of material spirally wound on a flat plane to produce a spiral with adjacent turns with spacer elements provided between adjacent turns of the spiral.
A method of gas injection moulding comprising the steps of:
- providing a gas injection and exhaust needle assembly comprising at least a gas inlet channel and a separate gas outlet channel with a flow restrictor in one of the gas inlet and gas outlet channels that:
- a) is sized such that in use gas may freely flow through the one channel but liquid moulding material may not flow freely therethrough;
- and b) comprises a strip of material spirally wound on a flat plane with adjacent turns between which spacer elements are provided;
- providing a mould with a melt therein;
- and
- directing a gas into the gas inlet channel and therefrom into the melt in the mould and from the melt to and through the gas outlet channel.
Dependencies are inferred from the claim text.