Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting – Controlling fluid pressure in direct contact with molding...
Patent
1990-03-29
1991-08-13
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
Controlling fluid pressure in direct contact with molding...
264 406, 2643288, 26432812, 26432813, 264572, 425812, B29C 4500, B29C 4576, B29C 4578, B29D 2200
Patent
active
050394630
ABSTRACT:
A method and apparatus for gas assisted injection molding. The apparatus includes a bulk storage container; a booster receiving the gas from the bulk storage container and operating to boost the pressure to a relatively high level for delivery to a high pressure storage container; a regulator receiving the gas from the high pressure storage container and reducing the gas pressure to a desired injection pressure; and a control system for injecting the gas into the mold, at the injection pressure as determined by the regulator, thereafter reducing the gas pressure within the mold to a hold pressure, thereafter maintaining the gas in the mold at the hold pressure, and thereafter venting the mold to atmosphere. The apparatus allows the performance of two distinct injection molding methods. In the first method, the regulated gas is injected directly into the mold, is held at the injection pressure during the fill out portion of the molding cycle, and is thereafter reduced to a hold pressure. In the second method, the gas from the regulator is stored in a plurality of fixed volume storage containers and is thereafter injected into the mold from a selected storage container so that, as the gas moves into the expanded volume of the mold during the fill out portion of the molding cycle, the injection pressure is caused to drop to a reduced pressure at which it is held for the duration of the cooling cycle whereafter the mold is vented and the mold opened.
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patent: 4855094 (1989-08-01), Hendry
patent: 4935191 (1990-06-01), Baxi
patent: 4943407 (1990-07-01), Hendry
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