Patent ID: 9738016
Date: 2017-08-22
CPC Classifications: B29C

Claim:
1. A method of injection molding of plastic materials into a mold cavity with a distributor of pressurized fluid plastic material connected to at least one injector comprising a pin valve displaceable between a fully closed position and an open position, the method comprising a filling step of said mold cavity with the pressurized plastic material following displacement of the pin valve from the fully closed position to the open position, a packing step of the pressurized plastic material within the mold cavity while the pin valve is kept in the open position, directly followed by an additional step of displacement of the pin valve from the open position directly to and kept in a single partially closed intermediate position, and then directly followed by displacement of the pin valve from the single partially closed intermediate position to the fully closed position, the method further comprising an absence of reopening the pin valve subsequent to displacement of the pin valve to the single partially closed intermediate position during an injection cycle; wherein a plurality of first and second injectors are arranged at a generally central zone and of one or more generally peripheral zones of the mold cavity, respectively, and wherein the filling step is performed by sequentially controlling said first and second injectors so that the pin valves of the first injectors are displaced from the fully closed position to the open position prior to the pin valves of the second injectors whereby the mold cavity is progressively filled from said generally central zone towards said one or more generally peripheral zones, and wherein said additional step is carried out only for the pin valves of the first injectors such that the pin valves of the second injectors remain in the open position during said additional step.