Patent US4327776A successfully refreshed from Google Patents.
US4327776A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thin-walled metal duct having integral reinforced coupling ends
Assignee: Johns Manville
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Filing: 1978-01-11
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Granted: 1982-05-04
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Expires: 1998-01-11
Abstract
Abstract Thin-walled metal duct particularly useful for heating and air-conditioning purposes is usually made by grooving, spiral wrapping, and seaming strips of thin metal sheet. The resultant tubular form provides the necessary rigidity to resist collapse of the tubular form. In the past, at least one end of the ribbed tubular ducts have been reformed to permit the ducts to be joined together. The end reforming techniques of the past have resulted in reformed ends having insufficient rigidity and strength to resist the abuse the ducts frequently receive in shipping, storing, handling, and installation. The present product, method, and apparatus provide a ribbed thin-walled tubular duct having reformed ends with rigidity and strength superior to the prior art products. This achievement is accomplished in the present invention by moving more metal into the end portion of the duct prior to reforming the end portion, thus reinforcing the end portion of the duct.
Inventors
- 👤 Robert H. Meserole
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:51
CPC Classifications
B; B21; B21D; B21D49/00; B21D15/00; B21D15/04; F; F16; F16L; F16L37/00; F16L37/02
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
217 words
In a tubular metal duct section formed by spirally wrapping and seaming a strip of metal around a mandrel wherein said strip of metal has longitudinally extending ribs and grooves, cutting the resulting tubular product into sections and reforming at least one end portion of each section so as to produce a tubular metal duct section comprising: (a) an intermediate portion having a wall with ribs and grooves therearound between turns of a spiral seam, and (b) at least one relatively stiff reformed end portion, integral with said intermediate portion, the improvement comprising: (i) said one end portion being stiffened and reinforced by being compressed axially so that the distance in an axial direction between adjacent turns of said spiral seam in said one end portion is substantially less than the distance in an axial direction between adjacent turns of said spiral seam in said intermediate portion, (ii) said stiffened and reinforced end portion having at least three layers of metal in a radial direction over a majority of its axial extent, each of said layers being in substantial parallel relationship with each other as viewed in axial cross-section through said end portion and each of said layers having at least one major surface in very close proximity to a major surface of another of said layers.
Claim 2
Dependent Claim
217 words
In a tubular metal duct section formed by spirally wrapping and seaming a strip of metal around a mandrel wherein said strip of metal has longitudinally extending ribs and grooves, cutting the resulting tubular product into sections and reforming at least one end portion of each section so as to produce a tubular metal duct section comprising: (a) an intermediate portion having a wall with ribs and grooves therearound between turns of a spiral seam, and (b) at least one relatively stiff reformed end portion, integral with said intermediate portion, the improvement comprising: (i) said one end portion being stiffened and reinforced by being compressed axially so that the distance in an axial direction between adjacent turns of said spiral seam in said one end portion is substantially less than the distance in an axial direction between adjacent turns of said spiral seam in said intermediate portion, (ii) said stiffened and reinforced end portion having at least three layers of metal in a radial direction over a majority of its axial extent, each of said layers being in substantial parallel relationship with each other as viewed in axial cross-section through said end portion and each of said layers having at least one major surface in very close proximity to a major surface of another of said layers.
Claim 3
Dependent Claim
52 words
A duct section as defined in claim 1 wherein a lengthwise cross-section through the wall of said end portion discloses that the three layers of metal form a series of generally flattened upright T-shaped members with a flattened inverted T-shaped member located between two adjacent flattened upright T-shaped members in the series.
Claim 4
Dependent Claim
34 words
A duct section as defined in claim 1 wherein a lengthwise cross-section through the wall of the end portion discloses that the three layers of metal form a series of generally flattened Z-shaped members.
Claim 5
Dependent Claim
32 words
A duct section as defined in claim 2 wherein at least three layers of metal in a radial direction are in at least 85% of the axial extent of said end portion.
Claim 6
Dependent Claim
32 words
A duct section as defined in claim 3 wherein at last three layers of metal in a radial direction are in at least 85% of the axial extent of said end portion.
Claim 7
Dependent Claim
20 words
A duct section as defined in claim 2 wherein said metal has a thickness of less than about 15 mils.
Claim 8
Dependent Claim
20 words
A duct section as defined in claim 5 wherein said metal has a thickness of less than about 15 mils.
Claim 9
Dependent Claim
54 words
A duct section as defined in claim 6 wherein both ends of the duct are reinforced and stiffened and one of the ends has a tapered extremity, tapering to a diameter sufficiently small to enable the tapered end portion to be inserted into an untapered reinforced and stiffened end portion of a second duct.
Claim 10
Dependent Claim
54 words
A duct section as defined in claim 7 wherein both ends of the duct are reinforced and stiffened and one of the ends has a tapered extremity, tapering to a diameter sufficiently small to enable the tapered end portion to be inserted into a untapered reinforced and stiffened end portion of a second duct.
Claim 11
Dependent Claim
26 words
A duct section as defined in claim 8 wherein the metal is a aluminum, or an alloy thereof, having a thickness of 10 mils or less.
Claim 12
Dependent Claim
25 words
A duct section as defined in claim 9 wherein the metal is aluminum or an alloy thereof having a thickness of 10 mils or less.
References Cited (Backward Citations)
US3207538A
Cited
US525061A
Cited
US1315548A
Cited
BE522825A
Cited
US1340818A
Cited
CH199026A
Cited
US2822194A
Cited
US2818281A
Cited
US2986169A
Cited
US3101209A
Cited
US3758139A
Cited
US3738394A
Cited
US3794364A
Cited
GB1405318A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-03 | 1985-11-02 | 1986-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-03 | 1989-11-02 | 1990-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-03 | 1993-11-02 | 1994-05-04 | $7700.00 | Window Closed / Lapsed |