US3733159A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for manufacture of void-free and warp-free slab stock
Assignee: Shell USA Inc
•
Filing: 1971-08-05
•
Granted: 1973-05-15
•
Expires: 1991-08-05
Abstract
Abstract Void-free slabs or billets of thermoplastic polymer are produced by cooling polymer melt in a mold under pressure while keeping part of the melt in contact with a heat-insulating deformable surface of the mold cavity. Apparatus of this invention comprises a mold having two parallel rigid planar surfaces, a deformable heat-insulating ring placed between said planar surfaces, stiffening or backing means to maintain the shape of the outer wall of the ring, and pressure means for controllable changing the distance between said surfaces.
Inventors
- 👤 P Coffman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:20
CPC Classifications
B; B29; B29C; B29C43/00; B29C43/32; B29C43/54; B29B; B29B11/00; B29B11/06; B29B11/12; B30; B30B; B30B15/00; B30B15/02; B30B15/022; B30B15/024; Y; Y10; Y10S; Y10S425/00; Y10S425/044; Y10S425/808; Y10S425/812
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
107 words
Apparatus for producing plastic billets comprising a mold consisting of two parallel rigid planar surfaces and a deformable, heat-insulating ring having flat bottom and top surfaces, arranged so that upon closure of the mold each of said bottom and top surfaces of said ring is in contact with one of said planar surfaces and the mold cavity is defined by portions of said rigid planar surfaces and the interior surface of said ring; reinforcing means for from about the central one fourth to about the central three fourths of the outer wall of said ring; and pressure means for controllably changing the distance between said mold surfaces.
Claim 2
Dependent Claim
107 words
Apparatus for producing plastic billets comprising a mold consisting of two parallel rigid planar surfaces and a deformable, heat-insulating ring having flat bottom and top surfaces, arranged so that upon closure of the mold each of said bottom and top surfaces of said ring is in contact with one of said planar surfaces and the mold cavity is defined by portions of said rigid planar surfaces and the interior surface of said ring; reinforcing means for from about the central one fourth to about the central three fourths of the outer wall of said ring; and pressure means for controllably changing the distance between said mold surfaces.
Claim 3
Dependent Claim
45 words
Apparatus according to claim 1 wherein said ring has at least four radial grooves in its top surface, spaced about equally from each other and having a depth no more than 15 percent of the height of the billet to be formed in said mold.
Claim 4
Dependent Claim
31 words
Apparatus according to claim 2 wherein said reinforcing means comprises a band of substantially non-deformable material around at least one third of the height of the outer wall of said ring.
Claim 5
Dependent Claim
16 words
Apparatus according to claim 2 wherein the inner wall of said ring is of concave curvature.
References Cited (Backward Citations)
US2172243A
Cited
US2714226A
Cited
US2965946A
Cited
US3079642A
Cited
US3235643A
Cited
US3478135A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-14 | 1976-11-13 | 1977-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-14 | 1980-11-13 | 1981-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-14 | 1984-11-13 | 1985-05-15 | $7700.00 | Window Closed / Lapsed |