US4948547A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the use of gas assistance in the molding of plastic articles
Assignee: Melea Ltd
•
Filing: 1989-09-18
•
Granted: 1990-08-14
•
Expires: 2009-09-18
Abstract
Abstract A method of gas-assisted injection molding in which a charge of pressurized gas is injected into the mold, but not into the article-defining cavity. The gas charge is of a predetermined quantity and pressure sufficient to assist in filling out the article-defining cavity with resin and promoting surface quality. In another feature, the gas pressure within the resulting molding may be relieved by separating the mold halves and permitting the gas-containing portion of the molding to self-rupture, or by means well known in the art.
Inventors
- 👤 James W. Hendry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:45
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/1703; B29C45/1704; B29C45/46; B29C45/57; Y; Y10; Y10S; Y10S425/00; Y10S425/812
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
129 words
An improved method for the use of gas-assistance in the molding of a plastic article in an injection molding system including a mold having an injection aperture, the method comprising the steps of: injecting an amount of molten plastic resin sufficient for the preparation of the plastic article through the injection aperture and along a resin flow path which extends from the injection aperture to an article-defining cavity in the mold; injecting a charge of pressurized gas into the mold, said gas charge being of pressure and quantity sufficient to enter the resin flow path but not into the article-defining cavity; maintaining the gas charge under pressure within the mold while the plastic resin solidifies within the article-defining cavity; and relieving the gas pressure within said resin flow path.
Claim 2
Dependent Claim
129 words
An improved method for the use of gas-assistance in the molding of a plastic article in an injection molding system including a mold having an injection aperture, the method comprising the steps of: injecting an amount of molten plastic resin sufficient for the preparation of the plastic article through the injection aperture and along a resin flow path which extends from the injection aperture to an article-defining cavity in the mold; injecting a charge of pressurized gas into the mold, said gas charge being of pressure and quantity sufficient to enter the resin flow path but not into the article-defining cavity; maintaining the gas charge under pressure within the mold while the plastic resin solidifies within the article-defining cavity; and relieving the gas pressure within said resin flow path.
Claim 3
Dependent Claim
38 words
The method as described in claim 1 wherein the step of relieving the molding comprises separation of mold halves of the mold to cause self-rupture of the plastic resin containing the pressurized gas in the resin flow path.
Claim 4
Dependent Claim
31 words
The method as described in claim 1 wherein the step of relieving the molding includes the step of opening the resin flow path to permit ventilation of the gas contained therein.
Claim 5
Dependent Claim
25 words
The method as described in claim 3 wherein the step of opening includes the step of piercing the plastic resin to form an aperture therein.
Claim 6
Dependent Claim
26 words
The method as described in claim 3 wherein the step of opening includes the step of shearing the plastic resin to ventilate the gas contained therein.
Claim 7
Independent Claim
180 words
A method for injection molding of a plastic article having at least one substantially planar portion in an injection molding system including a mold having an injection aperture, the method comprising the steps of: injecting an amount of molten plastic resin sufficient for the preparation of the plastic article through the injection aperture and along a resin flow path which extends from the injection aperture to an article-defining cavity, said resin flow path including a portion which is substantially contiguous to a portion of the article-defining cavity corresponding to the substantially planar portion; injecting a charge of pressurized gas into the mold, said gas charge being of pressure and quantity sufficient to enter into a contiguous portion of the resin flow path contiguous to the portion of the article-defining cavity corresponding to the substantially planar portion, and not into the article-defining cavity; maintaining the gas charge under pressure in the contiguous portion during solidification of the plastic resin within the article-defining cavity; and relieving the gas pressure within said contiguous portion preparatory to removing said plastic article from the mold.
Claim 8
Independent Claim
180 words
A method for injection molding of a plastic article having at least one substantially planar portion in an injection molding system including a mold having an injection aperture, the method comprising the steps of: injecting an amount of molten plastic resin sufficient for the preparation of the plastic article through the injection aperture and along a resin flow path which extends from the injection aperture to an article-defining cavity, said resin flow path including a portion which is substantially contiguous to a portion of the article-defining cavity corresponding to the substantially planar portion; injecting a charge of pressurized gas into the mold, said gas charge being of pressure and quantity sufficient to enter into a contiguous portion of the resin flow path contiguous to the portion of the article-defining cavity corresponding to the substantially planar portion, and not into the article-defining cavity; maintaining the gas charge under pressure in the contiguous portion during solidification of the plastic resin within the article-defining cavity; and relieving the gas pressure within said contiguous portion preparatory to removing said plastic article from the mold.
Claim 9
Dependent Claim
46 words
The method as described in claim 6 wherein the step of relieving the molding includes separating mold halves of the mold to permit self-rupturing of the portion of the resin flow path contiguous to the portion of the article-defining cavity corresponding to the substantially planar portion.
Claim 10
Dependent Claim
44 words
The method as described in claim 6 wherein the step of relieving the molding includes the step of opening the resin flow path contiguous to the portion of the article-defining cavity defining the substantially planar portion to permit ventilation of the gas contained therein.
Claim 11
Dependent Claim
25 words
The method as described in claim 8 wherein the step of opening includes the step of piercing the plastic resin to form an aperture therein.
Claim 12
Dependent Claim
28 words
The method as described in claim 8 wherein the step of opening includes the step of shearing the plastic resin to permit ventilation of the gas contained therein.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-13 | 1994-02-12 | 1994-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-13 | 1998-02-12 | 1998-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-13 | 2002-02-12 | 2002-08-14 | $7700.00 | Window Closed / Lapsed |