EP0309182A2
Expired / Lapsed
EP
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Method, system and device utilized therein for injection molding and plastic article produced thereby
Assignee: Melea Ltd
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Filing: 1988-09-19
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Granted: —
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Expires: 2008-09-19
Abstract
Abstract A method, system and device utilized therein for the injection molding of plastic articles of enhanced surface quality using pressurized fluid. The fluid is prevented from contaminating the molten resin in the nozzle from which it was injected to thereby eliminate splay. The method involves the initial step of injecting molten resin at a nominal injection pressure from the nozzle of an injection molding machine through a resin injection aperture at an upstream position in a mold. The resin travels along a resin flow path in the mold to a mold cavity defining the shape of the molded article at a downstream position. The device at least partially defines the resin flow path in the mold. A charge of fluid pressurized at a predetermined level is communicated to the resin flow path through an orifice in the device which opens to the resin flow path. During or after resin injection the pressurized charge of fluid enters the flow path at the orifice and passes into the mold cavity to distribute the molten plastic within the mold cavity. The fluid is contained within the mold cavity under pressure until the article has set up, and is thereafter vented to the atmosphere. The device prevents the pressurized fluid from traveling back along the resin flow path and through the injection aperture. The device thereby prevents contamination of the molten resin in the nozzle.
Inventors
- 👤 James W. Hendry
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 12:08
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/1703; B29C45/1734; B29C45/1735; B29C45/1704; B29C45/1732; Y; Y10; Y10S; Y10S425/00; Y10S425/812
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
206 words
A method for the injection molding of a plastic article in an injection molding system including a resin injection nozzle and a mold having an injection aperture for receiving molten resin from the nozzle at an upstream position, a mold cavity at a downstream position and a resin flow path for fluidly communicating the injection aperture and the mold cavity between the upstream and downstream positions, the method comprising the steps of: pressurizing a charge of fluid at a predetermined pressure level; injecting a quantity of molten plastic from the injection nozzle through the injection aperture and the flow path and into the mold cavity at a nominal plastic injection pressure; communicating the charge of pressurized fluid to an orifice opening to the resin flow path in the mold between the upstream and downstream positions; introducing the fluid charge into the flow path from the orifice simultaneously with or after the step of injecting to distribute the molten plastic within the mold cavity; preventing the introduced fluid charge from traveling from the flow path, through the injection aperture and into the injection nozzle; containing the fluid under pressure within the article until it has set up in the mold cavity; and venting the fluid to ambient.
Claim 2
Independent Claim
206 words
A method for the injection molding of a plastic article in an injection molding system including a resin injection nozzle and a mold having an injection aperture for receiving molten resin from the nozzle at an upstream position, a mold cavity at a downstream position and a resin flow path for fluidly communicating the injection aperture and the mold cavity between the upstream and downstream positions, the method comprising the steps of: pressurizing a charge of fluid at a predetermined pressure level; injecting a quantity of molten plastic from the injection nozzle through the injection aperture and the flow path and into the mold cavity at a nominal plastic injection pressure; communicating the charge of pressurized fluid to an orifice opening to the resin flow path in the mold between the upstream and downstream positions; introducing the fluid charge into the flow path from the orifice simultaneously with or after the step of injecting to distribute the molten plastic within the mold cavity; preventing the introduced fluid charge from traveling from the flow path, through the injection aperture and into the injection nozzle; containing the fluid under pressure within the article until it has set up in the mold cavity; and venting the fluid to ambient.
Claim 3
Dependent Claim
38 words
A method according to Claim 1 wherein the difference in pressure between the nominal plastic injection pressure and the predetermined pressure level of the charge of fluid prevents the fluid charge from entering the path at the orifice.
Claim 4
Dependent Claim
56 words
A method according to Claim 1 wherein the step of preventing is accomplished by introducing the fluid charge into the flow path at a fluid injection position, the resin having a greater resistance to fluid charge travel between the fluid injection position and the upstream position than between the fluid injection position and the downstream position.
Claim 5
Dependent Claim
13 words
A plastic article molded in accordance with a method according to Claim 1.
Claim 6
Dependent Claim
170 words
An injection molding system for the injection molding of plastic articles comprising: an injection molding machine including an injection nozzle for injecting molten plastic through the nozzle; a mold having a resin injection aperture for receiving the molten plastic at an upstream position, a cavity defining the shape of the molded article at a downstream position and a plastic flow path for fluidly communicating the injection aperture and the cavity between the upstream and downstream positions; fluid charge means for pressurizing a charge of fluid at a predetermined level; and fluid circuit means interconnecting the flow path and the fluid charge means between the upstream and downstream positions at an orifice opening to the flow path for introducing the fluid charge into the flow path simulatneously with or after plastic injection, so that the fluid charge distributes the molten plastic in the mold cavity; said fluid circuit means including means for preventing the introduced fluid charge from travelling from the flow path through the injection aperture and into the nozzle.
Claim 7
Dependent Claim
170 words
An injection molding system for the injection molding of plastic articles comprising: an injection molding machine including an injection nozzle for injecting molten plastic through the nozzle; a mold having a resin injection aperture for receiving the molten plastic at an upstream position, a cavity defining the shape of the molded article at a downstream position and a plastic flow path for fluidly communicating the injection aperture and the cavity between the upstream and downstream positions; fluid charge means for pressurizing a charge of fluid at a predetermined level; and fluid circuit means interconnecting the flow path and the fluid charge means between the upstream and downstream positions at an orifice opening to the flow path for introducing the fluid charge into the flow path simulatneously with or after plastic injection, so that the fluid charge distributes the molten plastic in the mold cavity; said fluid circuit means including means for preventing the introduced fluid charge from travelling from the flow path through the injection aperture and into the nozzle.
Claim 8
Dependent Claim
52 words
A system according to Claim 5 wherein the fluid circuit means includes valve means having open and closed positions, said valve means introducing the fluid charge to the flow path through the orifice in the open position and preventing communication of the fluid charge to the flow path in the closed position.
Claim 9
Dependent Claim
142 words
For use with an injection molding system of the type including an injection nozzle and a mold having a mold cavity at a downstream position, a resin injection aperture at an upstream position and a resin flow path for fluidly communicating the injection aperture and the mold cavity, a device for assisting in the introduction of pressurized fluid into the cavity and for preventing the fluid from travelling from the flow path, through the injection aperture and into the nozzle, the device comprising: a body adapted to seat in the mold between the upstream and downstream positions, said body defining at least part of the resin flow path communicating the injection aperture with the cavity, the body having an orifice opening to the flow path, an external fluid port and a fluid passage extending between the external fluid port and the orifice.
Claim 10
Dependent Claim
142 words
For use with an injection molding system of the type including an injection nozzle and a mold having a mold cavity at a downstream position, a resin injection aperture at an upstream position and a resin flow path for fluidly communicating the injection aperture and the mold cavity, a device for assisting in the introduction of pressurized fluid into the cavity and for preventing the fluid from travelling from the flow path, through the injection aperture and into the nozzle, the device comprising: a body adapted to seat in the mold between the upstream and downstream positions, said body defining at least part of the resin flow path communicating the injection aperture with the cavity, the body having an orifice opening to the flow path, an external fluid port and a fluid passage extending between the external fluid port and the orifice.
Claim 11
Dependent Claim
24 words
A device according to Claim 7 wherein the orifice is dimensioned to be sufficiently small to resist entry of the relatively viscous molten resin.
Claim 12
Dependent Claim
30 words
A device according to Claim 7 wherein the orifice is positioned to introduce the fluid co-linearly with the direction of resin flow from the upstream position to the downstream position.
Claim 13
Dependent Claim
28 words
A device according to Claim 7 wherein the mold includes a sprue having a sprue opening and wherein the device is adapted to seat in the sprue opening.
References Cited (Backward Citations)
No citation records indexed.
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