US4016231A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for molding articles of thermoplastic sheet materials
Assignee: Transamerica Business Credit Corp
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Filing: 1975-10-22
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Granted: 1977-04-05
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Expires: 1995-10-22
Abstract
Abstract Method for molding three dimensional articles of thermoplastic sheet material which after molding will withstand the high temperatures of autoclaving for sterilization in hospital use without distortion. Molding is accomplished by providing a low mass mold made of sheet metal which has low heat sink characteristics and is adapted to providing a high degree of temperature uniformity by being made of substantially uniform thickness high thermal conductivity material heated by convection hot air means for a preselected dwell time with the consequent attainment of thermal stability during formation of the article.
Inventors
- 👤 Carl J. Hawkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:00
CPC Classifications
B; B29; B29C; B29C51/00; B29C51/26; B29C51/30; B29C51/36; B29C51/42; B29C51/426; B29C51/428
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
174 words
A method of molding thermo-formable sheet material into three dimensional articles comprising; placing a planar sheet of the thermo-formable sheet material in heat transfer relation over the cavity surface of a relatively thin mold of substantially uniform thickness having an exposed underside and conforming in shape to the article to be formed, flowing a heated fluid from directly under the mold into communication with the exposed underside of said mold opposite said cavity surface to convection heat said mold to a preselected temperature uniformly throughout, transmitting heat from said mold to said overlying sheet material, drawing said heated sheet material into communication with the heated cavity surface of said uniform thickness mold, retaining said drawn sheet material in communication with said mold surface and continuing to supply heat to said mold and to said drawn sheet for a preselected dwell period for establishment of a predeterminable high temperature dimensionally stable condition of said formed article, and then forcefully cooling said mold and sheet material uniformly and withdrawing the shaped article from said mold cavity.
Claim 2
Independent Claim
174 words
A method of molding thermo-formable sheet material into three dimensional articles comprising; placing a planar sheet of the thermo-formable sheet material in heat transfer relation over the cavity surface of a relatively thin mold of substantially uniform thickness having an exposed underside and conforming in shape to the article to be formed, flowing a heated fluid from directly under the mold into communication with the exposed underside of said mold opposite said cavity surface to convection heat said mold to a preselected temperature uniformly throughout, transmitting heat from said mold to said overlying sheet material, drawing said heated sheet material into communication with the heated cavity surface of said uniform thickness mold, retaining said drawn sheet material in communication with said mold surface and continuing to supply heat to said mold and to said drawn sheet for a preselected dwell period for establishment of a predeterminable high temperature dimensionally stable condition of said formed article, and then forcefully cooling said mold and sheet material uniformly and withdrawing the shaped article from said mold cavity.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein the uniform thickness mold is heated by convection with hot air communicated with the underside of said mold.
Claim 4
Dependent Claim
31 words
The method of claim 2 wherein the uniform thickness mold is heated to and maintained for the dwell period at a temperature approaching but short of disruption of said sheet material.
Claim 5
Dependent Claim
16 words
The method of claim 3 wherein the uniform thickness mold is cooled by convection with air.
Claim 6
Dependent Claim
15 words
The method of claim 4 wherein the convection air is cooled air below atmosphere temperature.
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) | 1980-04-04 | 1980-10-04 | 1981-04-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-04 | 1984-10-04 | 1985-04-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-04 | 1988-10-04 | 1989-04-05 | $7700.00 | Window Closed / Lapsed |