US3840239A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compression molding in a vacuum and seal for use therein
Assignee: Aerojet Rocketdyne Holdings Inc
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Filing: 1972-10-26
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Granted: 1974-10-08
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Expires: 1992-10-26
Abstract
Abstract It has been discovered that by compression molding plastics with the entire mold chamber evacuated well below atmospheric pressure, it is possible to minimize the number of surface defects of the type known as porosity. This discovery is based upon the finding that porosity is caused by air which is trapped between the molding compound and the surface of the mold cavity, and also by air which is trapped between converging flow fronts of adjacent charges of molding compound. To enable the evacuation of the mold chamber, a vacuum seal is provided which comprises a belt-like wall member having reinforcing members embedded vertically within the wall. As the mold halves converge, the bottom edge of the seal engages the outer surface of the base member thereby sealing the chamber from the atmosphere, and the chamber is then evacuated before pressure is applied to the molding compound.
Inventors
- 👤 T Fazekas
- 👤 W Hartz
- 👤 N Muth
- 👤 R Stadelman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:11
CPC Classifications
B; B29; B29C; B29C43/00; B29C43/32; B29C43/56; B29C43/36; B29C43/3607; F; F16; F16J; F16J15/00; F16J15/16; F16J15/32; F16J15/3204; Y; Y10; Y10S; Y10S277/00; Y10S277/913
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
169 words
Apparatus comprising: a. a first member; b. a second member terminating in a portion tapering toward said first member; and c. a seal adapted to define, with said first and second members, a chamber, said seal comprising: i. a belt-like elastomeric wall member oriented generally parallel to the axis of taper of said second member; ii. attaching means mounted adjacent the top of said wall member for sealingly attaching said seal to said first member; iii. a plurality of elongated reinforcing members fixedly mounted in contaact with said wall member, said reinforcing members oriented generally parallel to the axis of taper of said second member and having suffiCient rigidity to be only slightly deformed inwardly when the chamber is subjected to a vacuum; and iv. said wall member defining a leading edge oppositely disposed from the top of said wall member to slidingly and sealingly engage said tapered portion of said second member while said first and second members are moving from their maximum separation to their minimum separation.
Claim 2
Dependent Claim
169 words
Apparatus comprising: a. a first member; b. a second member terminating in a portion tapering toward said first member; and c. a seal adapted to define, with said first and second members, a chamber, said seal comprising: i. a belt-like elastomeric wall member oriented generally parallel to the axis of taper of said second member; ii. attaching means mounted adjacent the top of said wall member for sealingly attaching said seal to said first member; iii. a plurality of elongated reinforcing members fixedly mounted in contaact with said wall member, said reinforcing members oriented generally parallel to the axis of taper of said second member and having suffiCient rigidity to be only slightly deformed inwardly when the chamber is subjected to a vacuum; and iv. said wall member defining a leading edge oppositely disposed from the top of said wall member to slidingly and sealingly engage said tapered portion of said second member while said first and second members are moving from their maximum separation to their minimum separation.
Claim 3
Dependent Claim
14 words
The apparatus of claim 1 wherein said wall member comprises an elastomeric rubber material.
Claim 4
Dependent Claim
44 words
The apparatus of claim 1 wherein said wall member has a height, parallel to the axis of taper of said second member, of at least about 3 inches and a substantially uniform thickness of between about one-quarter of an inch and about 1 inch.
Claim 5
Dependent Claim
22 words
The apparatus of claim 1 wherein said elongated reinforcing members are metal rods extending substantially the entire height of said wall member.
Claim 6
Dependent Claim
32 words
The apparatus of claim 5 wherein said metal rods are embedded within said wall member and are located on generally uniform center-to-center distances of from about one-half inch to about one inch.
Claim 7
Dependent Claim
20 words
The apparatus of claim 1 wherein said first member is attached to the press portion of a compression molding press.
Claim 8
Dependent Claim
36 words
The apparatus of claim 1 wherein said attaching means comprises an inturned flange formed integrally with said wall member, said flange maintaining said wall member in a configuration which is generally a rectangle with rounded corners.
Claim 9
Dependent Claim
43 words
The apparatus of claim 1 including means operative to begin evacuating the chamber when said leading edge of said seal engages said tapered portion, said evacuation continuing during substantially the entire time said first and second members are moving toward their minimum separation.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-07 | 1978-04-08 | 1978-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-07 | 1982-04-08 | 1982-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-07 | 1986-04-08 | 1986-10-08 | $7700.00 | Window Closed / Lapsed |