Switch for the flow of molten plastics material in a hot plate for injection moulding
AssigneeThermoplay S.p.A.
InventorPiero Enrietti
Life of this patent
Estimating the term…
Abstract
A cylindrical switch has one or more passages which open onto a lateral cylindrical surface of the switch. The switch is capable of being tightly received in a cylindrical hole in a hot plate and of being selectively orientated so that the passages are angularly in line with or offset from two or more channels in the hot plate which open onto the hole in order to selectively permit, interrupt or divert the flow of molten plastics material between the aforesaid channels. The switch incorporates a circuit for a cooling fluid.
Claims6
A cylindrical switch with at least one passage which opens on one lateral cylindrical surface of the switch, wherein the switch is capable of being tightly received within a cylindrical hole in a hot plate and selectively orientated in such a way as to angularly line up or offset the said passage with respect to at least two channels in the hot plate which open onto the hole, in order to selectively permit, interrupt or divert the flow of molten plastics material between the said channels, and wherein the switch incorporates a circuit for a cooling fluid.
A method for varying the connections between at least two channels of a hot plate to deliver molten plastics material to at least one injection nozzle, wherein in the plate said at least two channels open onto a cylindrical hole of given diameter in which a cylindrical switch with at least one passage which opens onto a lateral cylindrical surface of the switch is immobilised by radial interference, comprising the following steps:
- a) cooling the switch by causing a cooling fluid to circulate in a cooling circuit within the switch, at the same time keeping the plate in a heated condition, as a result of which the switch contracts canceling out or reducing the radial interference with respect to the hole,
- b) selectively rotating the switch in the hole in such a way as to bring the passage in the switch into a different angular position which is angularly in line with or offset from the said channels in the hot plate,
- c) interrupting the circulation of cooling fluid, allowing the switch to expand thermally and remain immobilised by radial interference in the hole in the plate in the angular position reached.
Dependencies are inferred from the claim text.