Patent US3867085A successfully refreshed from Google Patents.
US3867085A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermoforming apparatus with web support means
Assignee: NRM POLYMER EQUIPMENT Corp
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Filing: 1974-01-03
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Granted: 1975-02-18
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Expires: 1994-01-03
Abstract
Abstract Thermoforming apparatus wherein the opposite longitudinal edge portions of a sheet of thermoplastic material are gripped by an indexing conveyor which conveys the sheet through a heating oven wherein it is heated to forming temperature and through a thermoformer wherein the heated sheet is deformed into a mold cavity by pressure and/or vacuum, said apparatus being characterized in that at least the portion of the length of the heating oven adjacent the thermoformer has therein one or more perforated tubes which extend longitudinally between the gripped edges of the sheet with air being discharged upwardly through said tubes against the bottom surface of the sheet to form an air bearing support to inhibit sagging of the heated sheet between its gripped longitudinal edges. The apparatus herein is further characterized in that there is a heat interchange between the air and the sheet supporting tubes so that the latter are cooled to avoid possible overheating of the sheet thereabove while the air flowing through the tubes is heated so as not to have undue chilling effect on the regions of the sheet upon which the air jets impinge.
Inventors
- 👤 John R Lynch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:13
CPC Classifications
B; B29; B29B; B29B13/00; B29B13/02; B29B13/023; Y; Y10; Y10S; Y10S425/00; Y10S425/20
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
190 words
Thermoforming apparatus comprising an elongated heating oven into one end of which a thermoplastic web is introduced for transport therethrough for heating said web to forming temperature; a thermoformer adjacent the other end of said oven into which the heated web is transported for forming therein; a conveyor operative to grip the opposite longitudinal edge portions of said web to convey said web through said oven and thermoformer for respectively heating said web to forming temperature and forming the web; sag inhibiting web support means in said oven extending longitudinally from such other end of said oven toward such one end and disposed underneath said web to support the latter between its longitudinal edge portions, said means comprising at least one elongated tube laterally spaced between said edge portions and having a series of openings through the wall thereof juxtaposed to the bottom surface of the web; and a fluid pressure source to supply gaseous medium into said tube for flow upwardly through said openings to impinge on the web thereabove thus to define a gas bearing to facilitate transport of the web through said oven while inhibiting sagging thereof.
Claim 2
Dependent Claim
190 words
Thermoforming apparatus comprising an elongated heating oven into one end of which a thermoplastic web is introduced for transport therethrough for heating said web to forming temperature; a thermoformer adjacent the other end of said oven into which the heated web is transported for forming therein; a conveyor operative to grip the opposite longitudinal edge portions of said web to convey said web through said oven and thermoformer for respectively heating said web to forming temperature and forming the web; sag inhibiting web support means in said oven extending longitudinally from such other end of said oven toward such one end and disposed underneath said web to support the latter between its longitudinal edge portions, said means comprising at least one elongated tube laterally spaced between said edge portions and having a series of openings through the wall thereof juxtaposed to the bottom surface of the web; and a fluid pressure source to supply gaseous medium into said tube for flow upwardly through said openings to impinge on the web thereabove thus to define a gas bearing to facilitate transport of the web through said oven while inhibiting sagging thereof.
Claim 3
Dependent Claim
73 words
The apparatus of claim 1 Wherein said gaseous medium is introduced into said tube at a temperature substantially less than oven temperature and which gaseous medium is in heat exchange relation with said tube to cool the tube to less than oven temperature and to heat the air discharged through said openings so as not to have an undue chilling effect on the portions of the web upon which said air jets impinge.
Claim 4
Dependent Claim
67 words
The apparatus of claim 1 wherein said oven has heat shields on opposite sides thereof forming longitudinally extending gaps therebetween through which the edge portions of the web pass to protect the gripped edge portions from the high temperature in the oven; and wherein there are longitudinally spaced apart tube supporting brackets on the lower one of said shields to support said tube beneath the traveling web.
Claim 5
Dependent Claim
23 words
The apparatus of claim 3 wherein said brackets are laterally adjustable to predeterminately space said tube from the lateral edges of said web.
Claim 6
Dependent Claim
64 words
The apparatus of claim 1 wherein said tube has a laterally extending portion extending through one side of said oven in spaced relation beneath the traveling web and a longitudinally extending portion which slopes upwardly toward the web supporting portion thereof thus to provide an additional length of tube within said oven for preheating of said gaseous medium before reaching said series of openings.
Claim 7
Dependent Claim
31 words
The apparatus of claim 5 wherein said openings begin in the sloping portion of the tube to provide anprogressively increasing impingement effect as the sloping portion approaches the web supporting portion.
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) | 1978-02-17 | 1978-08-19 | 1979-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-17 | 1982-08-19 | 1983-02-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-17 | 1986-08-19 | 1987-02-18 | $7700.00 | Window Closed / Lapsed |