US3777446A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for wrapping a load with heat-shrinkable film
Assignee: FERNHOLT AND GIERSTEN AS
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Filing: 1972-02-07
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Granted: 1973-12-11
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Expires: 1992-02-07
Abstract
Abstract Method and apparatus for wrapping a load with heat-shrinkable film comprising the steps of initially providing the load with an open-bottomed envelope of heat-shrinkable film, positioning the load in a shrink tunnel, withdrawing air from the lower open end of the envelope in order to create a sub-pressure therein and simultaneously withdrawal of air from the tunnel space passing the lower side edges of the load, heat the air withdrawn from the tunnel space and the inside of the envelope, re-circulate the air into the tunnel space towards the top side of the load where the air currents will turn around and move downwards along the outside of the film envelope to the lower side edges of the load from where the air a-new is withdrawn from the tunnel space and fulfills a closed circulation loop.
Inventors
- 👤 O Graver
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:00
CPC Classifications
B; B65; B65B; B65B53/00; B65B53/02; B65B53/06; B65B53/063; B29; B29C; B29C35/00; B29C35/02; B29C35/04; B29C35/045
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
138 words
A method of wrapping a load with heat-shrinkable film that comprises the steps of initially providing the load with an openbottom envelope of heat-shrinkable film, positioning the load in a shrink tunnel, withdrawing air from the lower open end of the envelope in order to create a sub-pressure therein and simultaneously withdrawing air from the tunnel space past the lower side edges of the load, heating the air withdrawn from the tunnel space and the inside of the envelope, re-circulating same into the tunnel space in the form of upwardly directed air currents along the inside walls of the tunnel toward the top side of the load, causing the air currents to turn around and move downwards along the outside of the film envelope to the lower side edges of the load to provide a closed circulation loop.
Claim 2
Independent Claim
138 words
A method of wrapping a load with heat-shrinkable film that comprises the steps of initially providing the load with an openbottom envelope of heat-shrinkable film, positioning the load in a shrink tunnel, withdrawing air from the lower open end of the envelope in order to create a sub-pressure therein and simultaneously withdrawing air from the tunnel space past the lower side edges of the load, heating the air withdrawn from the tunnel space and the inside of the envelope, re-circulating same into the tunnel space in the form of upwardly directed air currents along the inside walls of the tunnel toward the top side of the load, causing the air currents to turn around and move downwards along the outside of the film envelope to the lower side edges of the load to provide a closed circulation loop.
Claim 3
Dependent Claim
245 words
An apparatus for wrapping a load with heat-shrinkable film which comprises: a shrink tunnel in the form of a closed top open bottom insulated box, a support for a load therein, said support providing lateral air openings between said support and the lower side edges of the load, an air conduit system beneath said support, said air conduit system including an upwardly open central shaft, initially laterally directed air conveying means leading from said shaft and ending in spaced port openings at the open bottom of the shrink tunnel, a fan means and an air-heating means positioned in said air conduit system, said fan means being arranged to simultaneously withdraw air from the film envelope and from the shrink tunnel space through said lateral openings between the support and the lower side edges of the load to move the air as upward air currents out through said port openings and along the inside walls of the shrink tunnel and back over the outside of the load to establish a closed air circulation system, wherein said support including said port openings, said air conduit system, said fan means and said heating means are built as an integral self-contained unit structurally independent of said shrink tunnel. 3 An apparatus according to claim 2 wherein the laterally directed air conveying means from said shaft comprises a plurality of air ducts ending in air port openings circumferentially arranged in the support adjacent the inside walls of the shrink tunnel.
Claim 4
Dependent Claim
19 words
An apparatus according to claim 2 wherein said fan means and said air-heating means are located in said shaft.
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) | 1976-12-10 | 1977-06-11 | 1977-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-10 | 1981-06-11 | 1981-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-10 | 1985-06-11 | 1985-12-11 | $7700.00 | Window Closed / Lapsed |