Patent US3870449A successfully refreshed from Google Patents.
US3870449A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Permanent flashpad for transfer molding
Assignee: Aerojet Rocketdyne Holdings Inc
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Filing: 1973-07-23
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Granted: 1975-03-11
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Expires: 1993-07-23
Abstract
Abstract In a transfer molding press, a pad of polymeric material of generally uniform thickness, and having a higher durometer than the charge material at room temperature, is attached to the bottom surface of the transfer ram and extends over substantially the entire area thereof. The permanent flashpad enables the thickness of the cured flashpad (which is scrap), and the possibility of underfilling the mold cavities to be reduced. In addition, the permanent flashpad seals against the surface of the transfer ram pot, substantially preventing leakage of the charge material under pressure.
Inventors
- 👤 Jerry D Stringfellow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:43
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/02; Y; Y10; Y10S; Y10S425/00; Y10S425/055; Y10S425/228
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
183 words
In a transfer molding press including a transfer ram having a substantially flat bottom surface, a transfer ram pot, a plate defining at least one mold cavity and a plate defining at least one sprue in open communication between the ram pot and the mold cavity, wherein the uncured charge material substantially fills the cavity and the sprue, the remainder of the charge material forming a flashpad of generally uniform thickness in the ram pot, the flashpad curing during the cure cycle and subsequently being scrapped, the improvement comprising: a pad of polymeric material of generally uniform thickness of about 0.100 to about 0.200 inch (2.54 - 5.08 mm) and having higher durometer than the charge material at room temperature, said durometer being in the range of about 80 to about 90 on the Shore A scale, said pad being attached to the bottom surface of the transfer ram and extending over substantially the entire area thereof, and said pad being adapted to effectively seal against the surface of the transfer ram pot, thereby substantially preventing leakage of the charge material under pressure.
Claim 2
Dependent Claim
183 words
In a transfer molding press including a transfer ram having a substantially flat bottom surface, a transfer ram pot, a plate defining at least one mold cavity and a plate defining at least one sprue in open communication between the ram pot and the mold cavity, wherein the uncured charge material substantially fills the cavity and the sprue, the remainder of the charge material forming a flashpad of generally uniform thickness in the ram pot, the flashpad curing during the cure cycle and subsequently being scrapped, the improvement comprising: a pad of polymeric material of generally uniform thickness of about 0.100 to about 0.200 inch (2.54 - 5.08 mm) and having higher durometer than the charge material at room temperature, said durometer being in the range of about 80 to about 90 on the Shore A scale, said pad being attached to the bottom surface of the transfer ram and extending over substantially the entire area thereof, and said pad being adapted to effectively seal against the surface of the transfer ram pot, thereby substantially preventing leakage of the charge material under pressure.
Claim 3
Dependent Claim
183 words
In a transfer molding press including a transfer ram having a substantially flat bottom surface, a transfer ram pot, a plate defining at least one mold cavity and a plate defining at least one sprue in open communication between the ram pot and the mold cavity, wherein the uncured charge material substantially fills the cavity and the sprue, the remainder of the charge material forming a flashpad of generally uniform thickness in the ram pot, the flashpad curing during the cure cycle and subsequently being scrapped, the improvement comprising: a pad of polymeric material of generally uniform thickness of about 0.100 to about 0.200 inch (2.54 - 5.08 mm) and having higher durometer than the charge material at room temperature, said durometer being in the range of about 80 to about 90 on the Shore A scale, said pad being attached to the bottom surface of the transfer ram and extending over substantially the entire area thereof, and said pad being adapted to effectively seal against the surface of the transfer ram pot, thereby substantially preventing leakage of the charge material under pressure.
Claim 4
Dependent Claim
183 words
In a transfer molding press including a transfer ram having a substantially flat bottom surface, a transfer ram pot, a plate defining at least one mold cavity and a plate defining at least one sprue in open communication between the ram pot and the mold cavity, wherein the uncured charge material substantially fills the cavity and the sprue, the remainder of the charge material forming a flashpad of generally uniform thickness in the ram pot, the flashpad curing during the cure cycle and subsequently being scrapped, the improvement comprising: a pad of polymeric material of generally uniform thickness of about 0.100 to about 0.200 inch (2.54 - 5.08 mm) and having higher durometer than the charge material at room temperature, said durometer being in the range of about 80 to about 90 on the Shore A scale, said pad being attached to the bottom surface of the transfer ram and extending over substantially the entire area thereof, and said pad being adapted to effectively seal against the surface of the transfer ram pot, thereby substantially preventing leakage of the charge material under pressure.
Claim 5
Dependent Claim
23 words
The improvement of claim 1 wherein the polymeric material is selected from the group consisting of a silicone rubber and a fluorocarbon polymer.
Claim 6
Dependent Claim
17 words
The improvement of claim 1 wherein said pad defines a slight downwardly-projecting bump above each said sprue.
Claim 7
Dependent Claim
17 words
The improvement of claim 1 wherein said pad is adapted to reduce the thickness of said flashpad.
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) | 1978-03-10 | 1978-09-09 | 1979-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-10 | 1982-09-09 | 1983-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-10 | 1986-09-09 | 1987-03-11 | $7700.00 | Window Closed / Lapsed |