US3744106A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for stretching plastic sheet material
Assignee: Foster Grant Co Inc
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Filing: 1971-11-23
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Granted: 1973-07-10
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Expires: 1991-11-23
Abstract
Abstract An apparatus for longitudinally stretching a continuous web of extensible material such as thermoplastic sheeting to produce a highly uniform stretch oriented film for use in the production of high quality optical elements. The web is stretched by applying a tensile stress to a length of the film moving between a pair of driven pinch-type restraining rolls and one or more pulling rolls driven at a rate greater than that of the restraining rolls to impart the desired degree of elongation. Softening heat is applied to the top surface of the film as the film emerges from the nip of the restraining rolls.
Inventors
- 👤 S Baum
- 👤 A Mayr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:47
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/02; B29C55/04; B29C55/06
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
286 words
A system for uniaxially stretch orienting thermoplastic film comprising a frame, film restraining and feeding means including a pair of pinch rolls, means mounting said pinch rolls one above the other on said frame for rotation about spaced parallel axes and for relative movement toward and away from one another, means for urging said pinch rolls toward one another to apply pressure to a running length of film passing therebetween, means for driving at least one of said pinch rolls about its rotational axis, means for cooling at least one of said pinch rolls to dissipate heat therefrom, pulling roll means, bearing means mounting said pulling roll means on said frame in position to draw a running length of film from said pinch rolls in a generally horizontal direction, means for driving said pulling roll means at a rate greater than the rate at which said pinch rolls are driven to thereby apply a tensileforce to said running length of film between said pinch rolls and said pulling roll means, a heating zone extending transversely across said film, an elongated heating bar, heating means extending longitudinally through and confined within said heating bar at the heating zone for applying heat thereto, and means mounting said heating bar on said frame at said heating zone in a position extending transversely of and closely adjacent to one surface of said film as the film emerges from the nip of said pair of pinch rolls, said mounting means positioning said heating bar closely adjacent said nip with at least a substantial portion of said heating bar disposed within the area between said nip and a plane extending transversely of said film and tangent to said pair of pinch rolls.
Claim 2
Independent Claim
286 words
A system for uniaxially stretch orienting thermoplastic film comprising a frame, film restraining and feeding means including a pair of pinch rolls, means mounting said pinch rolls one above the other on said frame for rotation about spaced parallel axes and for relative movement toward and away from one another, means for urging said pinch rolls toward one another to apply pressure to a running length of film passing therebetween, means for driving at least one of said pinch rolls about its rotational axis, means for cooling at least one of said pinch rolls to dissipate heat therefrom, pulling roll means, bearing means mounting said pulling roll means on said frame in position to draw a running length of film from said pinch rolls in a generally horizontal direction, means for driving said pulling roll means at a rate greater than the rate at which said pinch rolls are driven to thereby apply a tensileforce to said running length of film between said pinch rolls and said pulling roll means, a heating zone extending transversely across said film, an elongated heating bar, heating means extending longitudinally through and confined within said heating bar at the heating zone for applying heat thereto, and means mounting said heating bar on said frame at said heating zone in a position extending transversely of and closely adjacent to one surface of said film as the film emerges from the nip of said pair of pinch rolls, said mounting means positioning said heating bar closely adjacent said nip with at least a substantial portion of said heating bar disposed within the area between said nip and a plane extending transversely of said film and tangent to said pair of pinch rolls.
Claim 3
Dependent Claim
83 words
In a system for uniaxially stretch orienting thermoplastic film as defined in claim 1, the further improvement wherein said pair of pinch rolls comprises a first metal roll having a polished outer surface for contacting said film and a second roll having an outer coating of resilient material, said resilient material being deformable under influence of pressure from said means urging said pinch rolls toward one another whereby the length of film clamped between said pinch rolls in the nip thereof is increased.
Claim 4
Dependent Claim
46 words
In a system for uniaxially stretch orienting thermoplastic film as defined in claim 2, the further improvement wherein said pulling roll means comprises a pair of pinch rolls and means for urging said pinch rolls toward one another to apply pressure to the film passing therebetween.
Claim 5
Dependent Claim
57 words
A system for uniaxially stretch orienting thermo-plastic film as defined in claim 1, the further improvement wherein said heating bar means comprises an elongated metal bar having a generally flattened surface, and wherein said mounting means supports said heating bar means with said generally flattened surface in closely spaced relation to the top surface of said film.
Claim 6
Dependent Claim
55 words
In a system for uniaxially stretch orienting thermoplastic film as defined in Claim 4, the further improvement wherein said heating bar comprises an elongated generally triangu-lar shaped metal bar, said generally flattened surface being one side surface of said triangular metal bar, and heating means ex-tending longitudinally through said elongated bar for supplying heat thereto.
Claim 7
Dependent Claim
53 words
In a system for uniaxially stretch orienting thermoplastic film as defined in Claim 5, the further improvement wherein said mounting means comprises means for mounting said elongated metal bar with one edge directed generally toward said nip and with said flattened surface being inclined at a slight angle relative to said top surface.
Claim 8
Dependent Claim
267 words
In a system for uniaxially stretch orienting thermoplastic film, including a frame supporting a pair of pinch rolls mounted one above the other for rotation about spaced parallel axes and for relative movement toward and away from one another, means for urging the pinch rolls toward one another to apply pressure to a running length of film passing therebetween, drive means for rotating at least one of the pinch rolls about itS rotational axis, and driven pulling roll means mounted on the frame in position to draw a running length of film from the pinch rolls in a generally horizontal direction to thereby apply a tensile force and axially stretch the film between the pinch roll and the pulling roll means, the improvement comprising heating means defining a transverse heating band across said film between said pinch rolls and said pulling roll means and extending from the nip of said pulling rolls along the length of said film a predetermined distance with at least a major portion of said heating band being positioned between said nip line and a plane extending transversely of said film and tangent to said pinch rolls, said heating means including an elongated metal bar having a generally flattened surface, mounting means supporting said metal bar with said generally flattened surface in closely spaced relation to the top surface of said film, an opening formed in and extending longitudinally of said metal bar, and electrical resistance heating means mounted within said opening for heating said metal bar to thereby apply heat to said film uniformly across the width thereof within said heating band.
Claim 9
Dependent Claim
267 words
In a system for uniaxially stretch orienting thermoplastic film, including a frame supporting a pair of pinch rolls mounted one above the other for rotation about spaced parallel axes and for relative movement toward and away from one another, means for urging the pinch rolls toward one another to apply pressure to a running length of film passing therebetween, drive means for rotating at least one of the pinch rolls about itS rotational axis, and driven pulling roll means mounted on the frame in position to draw a running length of film from the pinch rolls in a generally horizontal direction to thereby apply a tensile force and axially stretch the film between the pinch roll and the pulling roll means, the improvement comprising heating means defining a transverse heating band across said film between said pinch rolls and said pulling roll means and extending from the nip of said pulling rolls along the length of said film a predetermined distance with at least a major portion of said heating band being positioned between said nip line and a plane extending transversely of said film and tangent to said pinch rolls, said heating means including an elongated metal bar having a generally flattened surface, mounting means supporting said metal bar with said generally flattened surface in closely spaced relation to the top surface of said film, an opening formed in and extending longitudinally of said metal bar, and electrical resistance heating means mounted within said opening for heating said metal bar to thereby apply heat to said film uniformly across the width thereof within said heating band.
Claim 10
Dependent Claim
24 words
In the system as defined in claim 7, the further improvement including means for cooling one of said pinch rolls to dissipate heat therefrom.
Claim 11
Dependent Claim
48 words
In the system as defined in claim 7, the further improvement wherein said metal bar is generally triangular in cross section, and wherein said metal bar cooperates with said top film surface and the adjacent top restraining roll to shield said heating band against excessive air currents therein.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-09 | 1977-01-08 | 1977-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-09 | 1981-01-08 | 1981-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-09 | 1985-01-08 | 1985-07-10 | $7700.00 | Window Closed / Lapsed |