US3740991A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tube bending process
Assignee: Individual
•
Filing: 1971-10-08
•
Granted: 1973-06-26
•
Expires: 1991-10-08
Abstract
Abstract A method of forming a bend in a normally rigid tube of a material which becomes plastic at an elevated temperature, in which the material of the tube portion to be bent is rendered plastic by heating means, supporting means being provided to ensure that the tube remains substantially dimensionally stable in cross-section during the bending, the supporting means consisting of intermediate zones kept under substantially normal temperature conditions, which conditions are realized by screening said zones by means of aluminium strips from heat supplied by said heating means.
Inventors
- 👤 L Walraven
- 👤 H Hoogenboom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 08:30
CPC Classifications
B; B29; B29B; B29B13/00; B29B13/02; B29B13/023; B29B13/024; B21; B21D; B21D7/00; B21D7/16; B21D9/00; B21D9/16; B21D9/18; B29C; B29C53/00; B29C53/02; B29C53/08; B29C53/083; B29C35/00; B29C35/02; B29C35/08; B29C35/0805; B29C2035/0822; B29C53/80; B29C53/84; B29L; B29L2023/00; B29L2023/22; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/4981; Y10T29/49812
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
68 words
A method of forming a bend in a normally rigid tube constructed of a material which becomes plastic at an elevated temperature comprising simultaneously heating to an elevated temperature a plurality of axially spaced apart circumferential band portions of the tube while maintaining the intermediate band portions which separate the heated band portions at substantially normal temperature; bending the tube over the desired angle; and cooling the tube.
Claim 2
Independent Claim
68 words
A method of forming a bend in a normally rigid tube constructed of a material which becomes plastic at an elevated temperature comprising simultaneously heating to an elevated temperature a plurality of axially spaced apart circumferential band portions of the tube while maintaining the intermediate band portions which separate the heated band portions at substantially normal temperature; bending the tube over the desired angle; and cooling the tube.
Claim 3
Dependent Claim
38 words
A method as in claim 1 wherein heating is effected by directing heat radiation onto the tube while isolating the intermediate band portions of the tube from the radiation by applying strips of radiation-reflective material around the tube.
Claim 4
Dependent Claim
27 words
A method as in claim 1 wherein the band portions to be heated and the intermediate band portions have, viewed in the circumferential direction, a tapered form.
Claim 5
Dependent Claim
22 words
A method as in claim 1 wherein heating is effected by applying electric heating strips around the tube in axially spaced relationship.
Claim 6
Dependent Claim
46 words
A method as in claim 1 wherein the tube is heated along only a portion of its length, said portion consisting of said band portions and said intermediate band portions, whereby at least one end portion of said tube remains unheated and retains its initial shape.
Claim 7
Dependent Claim
55 words
A method as in claim 5 wherein the tube is constructed of plastic material and wherein heating is effected by directing infra-red radiation onto that portion of the tube which is to be bent, the intermediate band portions being protected from heating by applying to the circumference of the tube strips of infra-red reflective material.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |