Patent US2009646A successfully refreshed from Google Patents.
US4088722A
Expired / Lapsed
US
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Method for molding a block of polyurethane foam having a flat upper surface
Assignee: Dunlop Ltd
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Filing: 1975-07-03
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Granted: 1978-05-09
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Expires: 1995-07-03
Abstract
Abstract A method is provided to make substantially flat-topped blocks of plastics foam, e.g. polyurethane, by a batch process. The foam-forming reaction mixture is dispensed into a cavity defined by a support and shaping members for the sides of the block. As the foaming commences the support is lowered so that the zone of contact between the shaping members and the foam remains constant. By this means the dome-shaped effect of free-foaming is avoided.
Inventors
- 👤 John Ernest Marjoram
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:40
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/58; B29C44/586; B29C33/00; B29C33/30; Y; Y10; Y10S; Y10S264/00; Y10S264/84
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
159 words
A method of moulding a discrete block of polyurethane foam having a substantially flat upper surface comprising: depositing a polyurethane foam-forming reaction mixture on a shallow tray support positioned within shaping members and movable relative thereto, applying a contact means to the top surface of said mixture to detect upward movement of said surface as a result of foam formation, foaming said mixture, detecting the upward movement of the top surface of said mixture during foaming and generating a signal to a power means to move said support downwardly inside of said shaping members at a rate corresponding to the rate of expansion of the mixture so that the sides of the mixture maintain sliding contact with the shaping members and are given the contour of the shaping members and maintaining said control means and the top surface of said mixture in a substantially unmovable position, said downward movement of said support stopping when said mixture ceases to expand.
Claim 2
Independent Claim
159 words
A method of moulding a discrete block of polyurethane foam having a substantially flat upper surface comprising: depositing a polyurethane foam-forming reaction mixture on a shallow tray support positioned within shaping members and movable relative thereto, applying a contact means to the top surface of said mixture to detect upward movement of said surface as a result of foam formation, foaming said mixture, detecting the upward movement of the top surface of said mixture during foaming and generating a signal to a power means to move said support downwardly inside of said shaping members at a rate corresponding to the rate of expansion of the mixture so that the sides of the mixture maintain sliding contact with the shaping members and are given the contour of the shaping members and maintaining said control means and the top surface of said mixture in a substantially unmovable position, said downward movement of said support stopping when said mixture ceases to expand.
Claim 3
Dependent Claim
18 words
The method of claim 1 in which said control means include a counterbalanced plate positioned above said support.
Claim 4
Dependent Claim
41 words
The method of claim 2 in which a thin sheet of material is placed between the counterbalanced plate and the upper surface of the foaming mixture, whereby the movement of said supper surface is detected and transmitted to said control means.
Claim 5
Dependent Claim
29 words
The method of claim 2 in which said thin sheet of material comprises a rigid foam having substantially the same density as that of the foam block being moulded.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-05-08 | 1981-11-07 | 1982-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-08 | 1985-11-07 | 1986-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-08 | 1989-11-07 | 1990-05-09 | $7700.00 | Window Closed / Lapsed |