US3908704A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Corrugated tubing
Assignee: Penntube Plastics Co
•
Filing: 1966-09-12
•
Granted: 1975-09-30
•
Expires: 1986-09-12
Abstract
Abstract The invention is concerned particularly with the production of corrugated tubing made from polytetrafluoroethylene or from the copolymer of tetrafluoroethylene and 5-35 percent of hexafluoropropylene which can be bent on a short radius to any desired shape and will retain its shape with or without substantial springback. In the preferred embodiment the corrugations extending outward from the tube have side walls of unequal length and in close-packed condition the side walls are inclined to the axis at an acute angle, producing a contour called cross-cut saw toothing or oil canning which will permit one corrugation to fold in under an adjoining corrugation in order to make very close bends. The tubing is then heat set in close-packed condition.
Inventors
- 👤 Ira T Clement
- 👤 Walter J Mccaw
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:21
CPC Classifications
A; A61; A61F; A61F2/00; A61F2/02; A61F2/04; A61F2/06; B; B29; B29C; B29C53/00; B29C53/22; B29C53/30; B29C71/00; B29C71/02; F; F16; F16J; F16J3/00; F16J3/04; F16J3/041; F16L; F16L11/00; F16L11/02; F16L11/04; F16L11/11; F16L11/111; Y; Y10; Y10S; Y10S138/00; Y10S138/03; Y10S277/00; Y10S277/935; Y10S277/944; Y10S277/945; Y10S277/946
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
145 words
A PLASTIC TUBING OF PLASTIC OF THE CLASS OF POLYTETRAFLUOROETHYLENE AND A COPOLYMER OF TERAFLUOROETHYLENE AND 5-35 PERCENT OF HEXAFLUOROPROPYLENE, HAVING A SEQUENCE OF ANNULAR CORRUGATIONS EXTENDING ALONG THE LENGTH OF THE TUBING, SAID CORRUGATIONS HAVING A CLOSE-PACKED POSITION IN WHICH THEY ADJOIN AND THE TUBE BEING STRETCHABLE UNTIL THE CORRUGATIONS ASSUME A LONGITUDINALLY SPACED POSITION, THE WALL THICKNESS THROUGHOUT THE CORRUGATIONS BEING SUBSTATIALLY UNIFORM, THE CORRUGATIONS HAVING SIDE WALLS ONE OF WHICH IS LONG AND THE OTHER OF WHICH IS SHORT, BOTH OF WHICH EXTEND AT AN ACUTE ANGLE WITH RESPECT TO THE AXIS, THE PLASTIC HAVING BEEN HEAT SET IN CLOSE-PACKED POSITION AT A TEMPERATURE WITHIN THE FOLLOWING RANGE FOR A TIME OF AT LEAST TEN MINUTES, POLYTETRAFLUOROETHYLENE 450-500*F. A COPOLYMER OF TETRAFLUOROETHYLENE AND 5-35% OF HEXAFLUOROPROPYLENE 300-400*F, AND THE TUBING WHEN BENT HOLDING ITS BEND SHAPE WITHOUT RETURNING TOWARD ITS PREVIOUS SHAPE.
Claim 2
Dependent Claim
145 words
A PLASTIC TUBING OF PLASTIC OF THE CLASS OF POLYTETRAFLUOROETHYLENE AND A COPOLYMER OF TERAFLUOROETHYLENE AND 5-35 PERCENT OF HEXAFLUOROPROPYLENE, HAVING A SEQUENCE OF ANNULAR CORRUGATIONS EXTENDING ALONG THE LENGTH OF THE TUBING, SAID CORRUGATIONS HAVING A CLOSE-PACKED POSITION IN WHICH THEY ADJOIN AND THE TUBE BEING STRETCHABLE UNTIL THE CORRUGATIONS ASSUME A LONGITUDINALLY SPACED POSITION, THE WALL THICKNESS THROUGHOUT THE CORRUGATIONS BEING SUBSTATIALLY UNIFORM, THE CORRUGATIONS HAVING SIDE WALLS ONE OF WHICH IS LONG AND THE OTHER OF WHICH IS SHORT, BOTH OF WHICH EXTEND AT AN ACUTE ANGLE WITH RESPECT TO THE AXIS, THE PLASTIC HAVING BEEN HEAT SET IN CLOSE-PACKED POSITION AT A TEMPERATURE WITHIN THE FOLLOWING RANGE FOR A TIME OF AT LEAST TEN MINUTES, POLYTETRAFLUOROETHYLENE 450-500*F. A COPOLYMER OF TETRAFLUOROETHYLENE AND 5-35% OF HEXAFLUOROPROPYLENE 300-400*F, AND THE TUBING WHEN BENT HOLDING ITS BEND SHAPE WITHOUT RETURNING TOWARD ITS PREVIOUS SHAPE.
Claim 3
Dependent Claim
22 words
Tubing of claim 1, which when fully extended has a length from 2 to 2 1/2 times the length when close packed.
Claim 4
Dependent Claim
17 words
Tubing of claim 1, in which the ratio of internal diameter to wall thickness is as follows:
Claim 5
Dependent Claim
69 words
A tube of thermoplastic material having a flexible zone intermediate the ends thereof, said flexible zone comprising a plurality of circumferential grooves, each of said grooves having sides of unequal length, said tube being contracted lengthwise at said flexible zone with the sides of said grooves reentrant and overlapping, and said tube being bendable about a short radius and being capable of holding a bent position without substantial springback.
Claim 6
Dependent Claim
69 words
A tube of thermoplastic material having a flexible zone intermediate the ends thereof, said flexible zone comprising a plurality of circumferential grooves, each of said grooves having sides of unequal length, said tube being contracted lengthwise at said flexible zone with the sides of said grooves reentrant and overlapping, and said tube being bendable about a short radius and being capable of holding a bent position without substantial springback.
Claim 7
Dependent Claim
38 words
A tube according to claim 4 wherein said grooves are identical and extend completely around the periphery of said cylinder, each of said grooves having two sides with one of said sides different in length than the other.
Claim 8
Dependent Claim
22 words
A tube according to claim 4 wherein said reetrant overlapping sides form folds having a component of direction axially of the tube.
Claim 9
Dependent Claim
32 words
A tube according to claim 6 wherein said flexible zone is expandable lengthwise by unfolding of said grooves, with partial expansion lengthwise of said flexible zone effecting axial bending of said tube.
Claim 10
Dependent Claim
30 words
A tube according to claim 4 wherein said tube is expandible lengthwise into an expanded position and is capable of holding said contracted and said expanded positions without substantial springback.
Claim 11
Dependent Claim
21 words
A tube according to claim 8, wherein said grooves are identical and each extends completely around the peripHery of said tubing.
Claim 12
Dependent Claim
25 words
A tube according to claim 8, wherein said sides are reetrant and overlap to form folds having a component of direction axially of the tube.
Claim 13
Dependent Claim
32 words
A tube according to claim 8, in which said flexible zone, when the circumferential grooves are fully extended, has a length from two to two and one-half times the length when contracted.
Claim 14
Dependent Claim
97 words
A heat-set plastic tubing in which the plastic has an ultimate elongation at room temperature prior to heat-setting of at least 100 percent, having a uniform wall thickness throughout its length, having a flexible zone intermediate the ends thereof, said flexible zone having been heat-set at a temperature lower than the melting temperature of the plastic, said flexible zone comprising a plurality of circumferential grooves, each of said grooves having sides of unequal length, said tube being contractable and expandable lengthwise and axially bendable with the ability to hold these positions without returning toward its previous shape.
Claim 15
Dependent Claim
97 words
A heat-set plastic tubing in which the plastic has an ultimate elongation at room temperature prior to heat-setting of at least 100 percent, having a uniform wall thickness throughout its length, having a flexible zone intermediate the ends thereof, said flexible zone having been heat-set at a temperature lower than the melting temperature of the plastic, said flexible zone comprising a plurality of circumferential grooves, each of said grooves having sides of unequal length, said tube being contractable and expandable lengthwise and axially bendable with the ability to hold these positions without returning toward its previous shape.
Claim 16
Dependent Claim
124 words
A heat-set plastic tubing of a plastic of the class consisting of polytetrafluoroethylene and a copolymer of tetrafluoroethylene and 5 to 35 percent of hexafluoropropylene with an ultimate elongation of at least 100 percent, having a uniform wall thickness throughout its length, having a sequence of annular corrugations extending along the length of the tubing, said corrugations having a close-packed position in which they adjoin and being stretchable until the corrugations assume a longitudinal spaced position, the corrugations having side walls one of which is long and the other of which is short, both of which extend at an acute angle with respect to the axis, such tubing being axially bendable with the ability to hold these positions without returning to its previous shape.
Claim 17
Dependent Claim
124 words
A heat-set plastic tubing of a plastic of the class consisting of polytetrafluoroethylene and a copolymer of tetrafluoroethylene and 5 to 35 percent of hexafluoropropylene with an ultimate elongation of at least 100 percent, having a uniform wall thickness throughout its length, having a sequence of annular corrugations extending along the length of the tubing, said corrugations having a close-packed position in which they adjoin and being stretchable until the corrugations assume a longitudinal spaced position, the corrugations having side walls one of which is long and the other of which is short, both of which extend at an acute angle with respect to the axis, such tubing being axially bendable with the ability to hold these positions without returning to its previous shape.
Claim 18
Dependent Claim
160 words
A conduit for conveying fluid, said conduit being formed from a straight piece of thermoplastic tubing of generally uniform circular cross section, said conduit defining a flexible zone intermediate its ends, said flexible zone comprising a sufficient multiplicity of substantially identical annular corrugations to permit said zone to bend closely about a short radius without obstruction of the internal flow path and without kinking, each of said annular corrugations having a saw-tooth configuration in longitudinal cross section when in an opened position and being defined by a pair of generally straight sidewalls of unequal length, said corrugations being disposed and compressed in close packed array in a closed position in which a shorter of the sidewalls of one corrugation is folded under a longer sidewall of an adjoining corrugation, said flexible zone being stretchable longitudinally from said closed position to assume said opened position, and retaining its bent shape without substantial springback when it is bent about a short radius.
Claim 19
Dependent Claim
160 words
A conduit for conveying fluid, said conduit being formed from a straight piece of thermoplastic tubing of generally uniform circular cross section, said conduit defining a flexible zone intermediate its ends, said flexible zone comprising a sufficient multiplicity of substantially identical annular corrugations to permit said zone to bend closely about a short radius without obstruction of the internal flow path and without kinking, each of said annular corrugations having a saw-tooth configuration in longitudinal cross section when in an opened position and being defined by a pair of generally straight sidewalls of unequal length, said corrugations being disposed and compressed in close packed array in a closed position in which a shorter of the sidewalls of one corrugation is folded under a longer sidewall of an adjoining corrugation, said flexible zone being stretchable longitudinally from said closed position to assume said opened position, and retaining its bent shape without substantial springback when it is bent about a short radius.
Claim 20
Dependent Claim
24 words
The conduit of claim 14, in which the flexible zone is bendable on a radius of the order of its own diameter or less.
References Cited (Backward Citations)
US1120268A
Cited
US2728356A
Cited
US3132980A
Cited
US3243328A
Cited
US3222441A
Cited
US3370118A
Cited
US3409224A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |