US3922134A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pipe bending mandrel
Assignee: ROBINTECH Inc
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Filing: 1973-12-17
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Granted: 1975-11-25
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Expires: 1993-12-17
Abstract
Abstract A method and means for bending pipe and other hollow bodies into arcuate shape while restraining collapsing tendencies of the walls by supporting the pipe internally on a close-fitting, crush-resistant flexible arbor, and expanding the arbor size by applying pressurized fluid within an annular deformable chamber or within flexible tubing wound helically about the periphery of the arbor. When bending thermo-plastic pipe which previously has been heated to above the deformation temperature in the areas to be deformed, circulating pressurized fluid also serves as a heat exchanger, hastening the cooling process.
Inventors
- 👤 Wilbur J Kupfrian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 01:06
CPC Classifications
B; B21; B21D; B21D9/00; B21D9/01; B29; B29C; B29C33/00; B29C33/44; B29C33/48; B29C33/50; B29C33/505; B29C53/00; B29C53/02; B29C53/08; B29C53/083; B29C53/80; B29C53/82; H; H02; H02G; H02G3/00; B29L; B29L2023/00; B29L2023/22
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
165 words
A mandrel insertable within a tube for supporting the interior walls of said tube and for inhibiting change in maintaining the cross-sectional contour of said walls while said tube is bent into a curved shape, said mandrel comprising a flexible central core member having a cross-sectional pattern corresponding in shape to but being smaller than the passageway through said tube, said core member being crush resistant, and an expandable peripheral zone enclosing said flexible core said zone being formed of a series of closely adjoining but axially-spaced encircling interconnected passages fully enclosing walls responsive to fluid pressure within said passages for expanding said elastomeric walls into resilient contact with adjoining areas of said core member while applying pressure to said interior walls throughout the portion of said tube to be bent, said zone being responsive upon dissipation of said pressure to recede from said interior walls, whereby sufficient peripheral clearance is developed to permit retraction of said mandrel from said tube following the bending operation.
Claim 2
Dependent Claim
165 words
A mandrel insertable within a tube for supporting the interior walls of said tube and for inhibiting change in maintaining the cross-sectional contour of said walls while said tube is bent into a curved shape, said mandrel comprising a flexible central core member having a cross-sectional pattern corresponding in shape to but being smaller than the passageway through said tube, said core member being crush resistant, and an expandable peripheral zone enclosing said flexible core said zone being formed of a series of closely adjoining but axially-spaced encircling interconnected passages fully enclosing walls responsive to fluid pressure within said passages for expanding said elastomeric walls into resilient contact with adjoining areas of said core member while applying pressure to said interior walls throughout the portion of said tube to be bent, said zone being responsive upon dissipation of said pressure to recede from said interior walls, whereby sufficient peripheral clearance is developed to permit retraction of said mandrel from said tube following the bending operation.
Claim 3
Dependent Claim
34 words
A mandrel as claimed in claim 1, including means for admitting and discharging circulating cooling fluid through said passages at sufficient pressure to expand said zone into firm heat-exchange contact with said interior walls.
Claim 4
Dependent Claim
18 words
A mandrel as claimed in claim 1, wherein said passages comprise elastomeric tubing spirally wrapped about said core.
Claim 5
Dependent Claim
38 words
A mandrel as claimed in claim 1, including an elastomeric cover encircling said annular passages, to provide more uniform distribution of pressure against said interior walls, and to assist in constricting said passages when said pressure is removed.
Claim 6
Dependent Claim
91 words
A mandrel insertable within a thermo-plastic, heat-softened conduit for supporting the walls of said conduit during a bending operation, said mandrel comprising a central arbor formed of flexible crush-resistant hose, an expandable peripheral zone comprising elastomeric tubing helically wrapped about said hose, and means for expanding said zone after said mandrel has been inserted within said conduit, said means comprising connections for admitting fluid under pressure to within said tubing, whereby said tubing is expanded for applying pressure to the inner walls of said conduit while said conduit is being bent.
Claim 7
Dependent Claim
91 words
A mandrel insertable within a thermo-plastic, heat-softened conduit for supporting the walls of said conduit during a bending operation, said mandrel comprising a central arbor formed of flexible crush-resistant hose, an expandable peripheral zone comprising elastomeric tubing helically wrapped about said hose, and means for expanding said zone after said mandrel has been inserted within said conduit, said means comprising connections for admitting fluid under pressure to within said tubing, whereby said tubing is expanded for applying pressure to the inner walls of said conduit while said conduit is being bent.
Claim 8
Dependent Claim
37 words
A mandrel as claimed in claim 5 wherein said arbor is a hose formed of helically-wound interlocked strip, adjoining interlocked turns being susceptible to slight relative axial motion, whereby said arbor bends substantially about its neutral axis.
Claim 9
Dependent Claim
27 words
A mandrel as claimed in claim 6, wherein said elastomeric tubing is wrapped about said arbor so as to lie in the grooves formed between adjacent turns.
Claim 10
Dependent Claim
46 words
A mandrel as claimed in claim 5 including an elastomeric cover formed about said peripheral zone, and positioned so as to be located in use between said zone and the walLs of said conduit thereby to impart to said walls pressure generated by said expanding zone.
Claim 11
Dependent Claim
43 words
A mandrel as claimed in claim 8, wherein said cover is stretched about said peripheral zone and has sufficient force to constrict said tubing and to reduce the outside diameter of the central arbor portion of said mandrel when said pressure is reduced.
Claim 12
Dependent Claim
24 words
A mandrel as claimed in claim 5 including a pilot formed at one end of said mandrel for guiding said mandrel within said conduit.
Claim 13
Dependent Claim
42 words
A mandrel as claimed in claim 5 including a pilot formed at one end of said mandrel for guiding said mandrel within said conduit, and including an elastomeric cover surrounding said peripheral zone and being secured at one end within said pilot.
Claim 14
Dependent Claim
48 words
A mandrel as claimed in claim 5 including an elastomeric cover for said peripheral zone, a pilot at one end of said mandrel, a handle at the opposite end of said mandrel, and internal connections for conducting fluid under pressure through said handle into communication with said tubing.
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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) | 1978-11-24 | 1979-05-26 | 1979-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-24 | 1983-05-26 | 1983-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-24 | 1987-05-26 | 1987-11-25 | $7700.00 | Window Closed / Lapsed |