US3896649A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for bending pipe
Assignee: METAUX INOXYDABLES OUVRES A CORP OF FRANCE
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Filing: 1974-03-04
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Granted: 1975-07-29
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Expires: 1994-03-04
Abstract
Abstract Large diameter thin-walled pipe is bent by a ram pushing the pipe forward axially and a bending arm forcing the forward end of the pipe to follow a curved path. A pair of gas burners mounted inside and outside the pipe in a plane passing through the center of the bend heat the pipe in a narrow bending zone to a temperature substantially reducing the yield strength of the metal.
Inventors
- 👤 James M Stuart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:32
CPC Classifications
B; B21; B21D; B21D9/00; B21D9/05; B21D9/07; B21D9/073; B21D7/00; B21D7/16; B21D7/162
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
99 words
A device for bending pipe comprising: a first burner means through which the pipe is passed to heat a narrow band of the exterior of the pipe to a temperature substantially reducing its yield point; second burner means around which the tube is passed to heat a narrow band of the interior of the tube to a temperature substantially reducing its yield point, said interior heated band and said exterior heated band being substantially opposite each other; means for feeding the pipe past said burners; and means for applying a bending moment to the heated portion of the pipe.
Claim 2
Independent Claim
99 words
A device for bending pipe comprising: a first burner means through which the pipe is passed to heat a narrow band of the exterior of the pipe to a temperature substantially reducing its yield point; second burner means around which the tube is passed to heat a narrow band of the interior of the tube to a temperature substantially reducing its yield point, said interior heated band and said exterior heated band being substantially opposite each other; means for feeding the pipe past said burners; and means for applying a bending moment to the heated portion of the pipe.
Claim 3
Dependent Claim
26 words
A device in accordance with claim 1 wherein said first and second burner means are located generally in a common plane perpendicular to the pipe axis.
Claim 4
Dependent Claim
40 words
A device in accordance with claim 2 and further comprising means associated with at least one of said burner means for cooling the pipe forward and rearward of said burner means to confine the heated area to a narrow band.
Claim 5
Dependent Claim
26 words
A device in accordance with claim 3 wherein said band extends axially along the pipe about twice to four times the thickness of the pipe wall.
Claim 6
Dependent Claim
27 words
A device in accordance with claim 3 wherein said cooling means comprises means exterior of the pipe for applying coolant to the exterior surface of said pipe.
Claim 7
Dependent Claim
33 words
A device in accordance with claim 3 wherein said cooling means comprises means both exterior and interior of the pipe for applying coolant to both the exterior and interior surfaces of said pipe.
Claim 8
Dependent Claim
35 words
A device in accordance with claim 2 and further comprising means coacting with the interior wall of said pipe and said second burner means to locate said second burner radially relative to said pipe wall.
Claim 9
Dependent Claim
29 words
A device in accordance with claim 7 wherein said second burner means and said first burner means are located on respective arcs centered on the axis of the pipe.
Claim 10
Dependent Claim
28 words
A device in accordance with claim 7 wherein said coacting means is a plurality of rollers mounted on said burner and engaging the interior wall of said pipe.
Claim 11
Dependent Claim
21 words
A device in accordance with claim 1 wherein the feeding means is a ram pushing the rear end of the pipe.
Claim 12
Dependent Claim
29 words
A device in accordance with claim 1 wherein the bending means is affixed to the forward end of the pipe and pivots about the center of bend being made.
Claim 13
Independent Claim
64 words
A method of bending a thin-walled pipe of large diameter comprising the steps of: heating the pipe both internally and externally with gas burners in a narrow band to a temperature substantially reducing its yield point; applying a bending moment to the pipe portion in the narrow band; and progressively moving the narrow band along the pipe as the portion in the band bends.
Claim 14
Independent Claim
64 words
A method of bending a thin-walled pipe of large diameter comprising the steps of: heating the pipe both internally and externally with gas burners in a narrow band to a temperature substantially reducing its yield point; applying a bending moment to the pipe portion in the narrow band; and progressively moving the narrow band along the pipe as the portion in the band bends.
Claim 15
Dependent Claim
36 words
A method in accordance with claim 12 further comprising the step of confining the width of the band having a substantially reduced yield point to approximately two to four times the wall thickness of the pipe.
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) | 1978-07-28 | 1979-01-27 | 1979-07-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-28 | 1983-01-27 | 1983-07-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-28 | 1987-01-27 | 1987-07-29 | $7700.00 | Window Closed / Lapsed |