US3687594A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for forming a plastic sheet
Assignee: RL ADAMS PLASTICS INC
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Filing: 1970-09-21
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Granted: 1972-08-29
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Expires: 1990-09-21
Abstract
Abstract An apparatus for forming a plastic sheet by differentially heating certain portions of the sheet of plastic previous to the differential pressure forming operation whereby as the plastic sheet is being formed the flow of plastic in the sheet is controlled. The plastic sheet is placed on a heating surface and a die is placed over the sheet. Heat is applied to the plastic sheet at certain predetermined portions thereof and after being heated to a desired state, a pressure differential is applied to the plastic sheet. As the differential pressure is applied to the sheet the portions which are at a greater degree of temperature flow and stretch more easily and thus the gauge or thickness of predetermined portions of the article being formed can be controlled.
Inventors
- 👤 Roger L Medendorp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:43
CPC Classifications
B; B29; B29C; B29C51/00; B29C51/26; B29C51/42; B29C51/421; B29C51/422
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
189 words
An apparatus for forming plastic articles from a sheet of plastic material comprising: a surface plate on which the sheet of plastic is laid; a heating source for heating said surface plate; a mold above said surface plate, said mold having a cavity; and means for subjecting said sheet of plastic laid on said surface sheet to a differential pressure on opposite sides thereof for causing said sheet of plastic to be deformed into the cavity of said mold, the improvement comprising: a heat conducting means positioned between said heating source and said heating surface plate for conducting heat therebetween; said heat conducting means having means for heating portions of said surface at different temperatures whereby a plastic sheet placed on said heating surface can be heated at different temperatures in different portions thereof; said heat conducting means between said surface plate and said heat source comprising a baffle plate with a plurality of openings extending entirely therethrough from said heat source to said surface plate, said openings being prearranged in size and position to produce the desired differential temperatures in the said different portions of said surface plate.
Claim 2
Independent Claim
189 words
An apparatus for forming plastic articles from a sheet of plastic material comprising: a surface plate on which the sheet of plastic is laid; a heating source for heating said surface plate; a mold above said surface plate, said mold having a cavity; and means for subjecting said sheet of plastic laid on said surface sheet to a differential pressure on opposite sides thereof for causing said sheet of plastic to be deformed into the cavity of said mold, the improvement comprising: a heat conducting means positioned between said heating source and said heating surface plate for conducting heat therebetween; said heat conducting means having means for heating portions of said surface at different temperatures whereby a plastic sheet placed on said heating surface can be heated at different temperatures in different portions thereof; said heat conducting means between said surface plate and said heat source comprising a baffle plate with a plurality of openings extending entirely therethrough from said heat source to said surface plate, said openings being prearranged in size and position to produce the desired differential temperatures in the said different portions of said surface plate.
Claim 3
Dependent Claim
32 words
The apparatus of claim 1 in which one of said openings in said baffle plate is centrally located and is relatively large compared to the size of the other of said openings.
Claim 4
Dependent Claim
70 words
The apparatus of claim 1 in which a substantial number of said plurality of openings in said baffle plate are aligned with and correspond to the holes in the heating surface plate whereby air can be conducted to the under side of said plastic sheet; one of said openings in said baffle plate being centrally located and relatively large compared to the size of the other of said openings therein.
Claim 5
Dependent Claim
45 words
The apparatus of claim 1 in which a substantial number of said plurality of openings in said baffle plate are aligned with and correspond to the holes in the heating surface plate whereby air can be conducted to the under side of said plastic sheet.
Claim 6
Dependent Claim
74 words
The apparatus of claim 4 in which the said plurality of openings in said baffle plate which are aligned with and correspond to holes in the heating surface plate are located adjacent the outer periphery of said mold and said large opening is located inwardly thereof whereby the portions of the plastic sheet adjacent the outer periphery of said mold are heated to a higher temperature than said portions located centrally of said mold.
Claim 7
Dependent Claim
60 words
The apparatus of claim 5 in which there are no openings in said baffle plate at the marginal edgEs thereof whereby the heat can flow freely at said marginal edges between the heat source and the surface plate to produce the highest concentration of heat at the marginal edges of the surface plate immediately adjacent the periphery of said mold.
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) | 1975-08-29 | 1976-02-28 | 1976-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-29 | 1980-02-28 | 1980-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-29 | 1984-02-28 | 1984-08-29 | $7700.00 | Window Closed / Lapsed |