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US3656233A
Expired / Lapsed
US
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Making polytetrafluoroethylene articles including tubes, and fittings employing such tubes, having improved concentricity and dimensional stability
Assignee: Dynalectron Corp
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Filing: 1968-11-19
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Granted: 1972-04-18
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Expires: 1988-11-19
Abstract
Abstract Starting from high quality, dense, and relatively dimensionally stable rods of polytetrafluoroethylene, the invention provides articles including tubes and fittings incorporating such tubes having very accurate concentricity and improved dimensional stability by: first machining and drilling the rod stock to provide desired exterior and interior dimensions, in some cases then shaping the tube to provide elbows and in other instances leaving them straight. Then the tubes are confined and their interior filled, and the ends are mechanically compressed with considerable end pressure. Then the assembly is heated to a temperature and for a time long enough to cause the polytetrafluoroethylene to expand and fill the very accurately made confining parts and to grip tightly the filling part, which is also very accurately made, allowing time enough at such temperature to obliterate the memory of former configurations of the polytetrafluoroethylene and thereby relieve the stresses incurred by previous manufacture and by the compressing. Then the assembly is cooled and the compressing parts removed. The finished part cannot thereafter shrink endwise and it retains its dimensions and concentricity.
Inventors
- 👤 John S Overholser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:00
CPC Classifications
H; H01; H01R; H01R24/00; H01R24/38; H01R24/40; B; B29; B29C; B29C53/00; B29C53/02; B29C53/08; B29C53/083; B29C67/00; B29C67/0014; B29C70/00; B29C70/68; B29C70/74; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29L; B29L2023/00; B29L2023/22; H01R2103/00; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49204; Y10T29/49208; Y10T29/4922
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
25 words
The method of claim 1 wherein said stock is cylindrical rod and said shaping comprises machining of said rod, said forcing-in exerting lengthwise pressure thereon.
Claim 2
Dependent Claim
25 words
The method of claim 2 wherein said stock is made tubular, with the interior filled before and during compression and heating by a rigid member.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein said stock is rod shaped and the shaping step is done by centerless grinding.
Claim 4
Dependent Claim
33 words
The method of claim 4 wherein the shaping includes drilling the rod to provide a tube and wherein the drilled opening is filled by a rigid part during compressing, heating, and maintaining steps.
Claim 5
Independent Claim
181 words
A method for securing a polytetrafluoroethylene sleeve to a cable having an inner conductor and an outer conductor separated by insulation, a Polytetrafluoroethylene tube around said outer conductor, and an outer cover around said tube, said sleeve having an inner diameter about that of the outer diameter of the outer cover, comprising the steps of: cutting off an end portion of the outer cover to expose the polytetrafluoroethylene tube, slipping the polytetrafluoroethylene sleeve over said cable around part of said outer tube and part of said cover, completely confining the exterior of said sleeve, forcing-in the end of said sleeve mechanically, heating the assembly to at least about 180* F. and well below the melting and sublimating points of the polytetrafluoroethylene, to provide a temperature sufficient to cause expansion of the polytetrafluoroethylene to fill the space within which it is confined, maintaining the assembly under the heat of the preceding step for a time sufficient to obliterate the memory of the polytetrafluoroethylene sleeve and to secure it to said tube, and cooling the assembly and removing the members used for forcing-in.
Claim 6
Independent Claim
228 words
A method for securing a polytetrafluoroethylene sleeve and terminal conductor in a water-tight connection to a cable having an inner conductor and an outer conductor separated by insulation, a polytetrafluoroethylene tube around said outer conductor, and an outer cover around said tube, said sleeve having an inner diameter about that of the outer diameter of the outer cover, comprising the steps of: cutting off an end portion of the outer cover to expose the polytetrafluoroethylene tube, cutting off a shorter portion of said tube to expose said outer conductor, inserting said terminal conductor as a sleeve beneath the end of said outer conductor, clamping said outer conductor against a flange of said sleeve, slipping the polytetrafluoroethylene sleeve over said cable around part of said outer tube and part of said cover, completely confining the exterior of said sleeve, forcing-in the end of said sleeve mechanically, heating the assembly to between about 180* F. and 500* F., to provide a temperature sufficient to cause the polytetrafluoroethylene to fill the space within which it is confined, thereby encasing the portion of said outer conductor around said terminal conductor, maintaining the assembly under the heat of the preceding step for a time sufficient to obliterate the memory of the polytetrafluoroethylene sleeve and to secure it to said tube and cover, and cooling the assembly and removing the members used for forcing-in.
Claim 7
Dependent Claim
76 words
The method of claim 1 wherein the stock material is rod stock comprising the steps of: machining the exterior surface of the rod and drilling through the center thereof to give a tube approximately the interior and exterior shapes desired, and filling the interior of said tube with a metal part and completely confining the exterior wall thereof in a metal mold, said metal mold and metal part having the desired finish accuracy, dimensions, and concentricity.
Claim 8
Dependent Claim
26 words
The method of claim 8 wherein said tube is bent to a curved shape before said forcing-in, being retained in that shape during the remaining steps.
Claim 9
Dependent Claim
15 words
The method of claim 8 wherein the metal part is permanently secured to the tube.
Claim 10
Dependent Claim
33 words
The method of claim 10 wherein after said filling step and before said confining step said tube is formed into a non-linear shape, and is maintained in that shape through the remaining steps.
Claim 11
Dependent Claim
21 words
The method of claim 11 wherein said confining step employs some parts to which said tube is to be permanently secured.
Claim 12
Dependent Claim
38 words
The method of claim 12 wherein said parts are provided with keying recesses into which the polytetrafluoroethylene of said tube flows during said heating and maintaining steps to provide projections extending from the as-machined wall of said tube.
Claim 13
Dependent Claim
47 words
The method of claim 10 wherein during said confining step a cylindrical metal sleeve is applied to and compressed to a cylindrical portion of said tube with a portion of said tube thereafter preventing removal of said sleeve, whereby said tube and sleeve make a rotary joint.
Claim 14
Dependent Claim
47 words
The method of claim 1 in which the article is a sleeve having an inner diameter about that of the outer diameter of a cable, comprising the steps of: slipping the sleeve over said cable and completely confining the sleeve in a mold while on the cable.
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) | 1975-04-18 | 1975-10-18 | 1976-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-18 | 1979-10-18 | 1980-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-18 | 1983-10-18 | 1984-04-18 | $7700.00 | Window Closed / Lapsed |