EP1119079A1 - Câble coaxial ainsi que procédé et dispositif de formation - Google Patents

Câble coaxial ainsi que procédé et dispositif de formation Download PDF

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Publication number
EP1119079A1
EP1119079A1 EP00308800A EP00308800A EP1119079A1 EP 1119079 A1 EP1119079 A1 EP 1119079A1 EP 00308800 A EP00308800 A EP 00308800A EP 00308800 A EP00308800 A EP 00308800A EP 1119079 A1 EP1119079 A1 EP 1119079A1
Authority
EP
European Patent Office
Prior art keywords
dielectric
outer conductor
cable
bead
coaxial cable
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00308800A
Other languages
German (de)
English (en)
Inventor
Henry J. Fauerbach
Joseph N. Caulfield
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Micro Coax Inc
Original Assignee
Micro Coax Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Micro Coax Inc filed Critical Micro Coax Inc
Publication of EP1119079A1 publication Critical patent/EP1119079A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R24/00—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure
    • H01R24/38—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts
    • H01R24/40—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency
    • H01R24/42—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency comprising impedance matching means or electrical components, e.g. filters or switches
    • H01R24/44—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency comprising impedance matching means or electrical components, e.g. filters or switches comprising impedance matching means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R2103/00—Two poles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
    • H01R43/28—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors for wire processing before connecting to contact members, not provided for in groups H01R43/02 - H01R43/26

Definitions

  • the invention relates to a method of forming the ends of a coaxial cable, and especially to a method of securing together the ends of the outer conducting layer and the inner dielectric layer.
  • a coaxial cable consists essentially of a center conductor, typically metal wire, a dielectric spacer, an outer conductor, typically of metal braid, and a protective jacket.
  • the dielectric spacer may be made of unsintered or partially sintered polytetrafluoroethylene (PTFE).
  • PTFE polytetrafluoroethylene
  • the PTFE is commonly either extruded onto the center conductor or in the form of a tape wrapped around the center conductor, typically in 3 to 10 layers wrapped helically. All such unsintered or partially sintered PTFE dielectrics will be referred to hereinafter as "expanded PTFE" (ePTFE).
  • the present invention proposes to sinter the different PTFE layers together at the end of the cable, so that they cannot move relative to one another, and to form the outer layer with a bead that engages the end of the metal braid, so that the PTFE cannot recede inside the braid.
  • a method of forming an end of a coaxial cable comprising center and outer conductors separated by a dielectric.
  • the dielectric is exposed beyond the end of the outer conductor.
  • the exposed dielectric is compressed axially, while confining it radially.
  • the dielectric is permitted to expand radially at a region adjacent to the end of the outer conductor so as to form a bead having an external diameter greater than the internal diameter of the outer conductor.
  • a coaxial cable comprising center and outer conductors separated by a dielectric, wherein at least one end of the dielectric projects lengthwise beyond the corresponding end of the outer conductor and is formed with an encircling bead that projects radially adjacent the end of the outer conductor sufficiently to prevent the dielectric receding within the outer conductor.
  • the step of permitting the dielectric to expand may comprise defining a gap between two axially-separated components and permitting the dielectric to expand into the said gap.
  • the width of the gap may be determined by a spacer, and the bead is then preferably formed radially inside the spacer, with free space remaining between the formed bead and the spacer.
  • One of the two said axially-separated components may be the outer conductor of the cable, and one of them may be a member that confines the exposed dielectric radially. The latter member may be a heated tool if the dielectric is thermoplastic.
  • apparatus for shaping an end of a coaxial cable comprising: a shroud of refractory material dimensioned to fit over the outer conductor of the cable, and having at one end a spacer lip dimensioned to abut the end of the outer conductor while defining a radial clearance from the outer surface of the dielectric of the cable; and a heated tool having a blind bore dimensioned to fit snugly over the dielectric of the cable and dimensioned to abut the spacer lip of the shroud.
  • the dielectric may be thermoplastic, especially PTFE, and may be heated sufficiently to soften it. If the dielectric is wound from tape or otherwise formed in layers, it is preferably heated sufficiently to fuse the layers in the exposed dielectric into a solid mass.
  • the bead may be shaped after it is formed to reduce the effect of any change in impedance at the transition between fused and unfused layers of the dielectric.
  • the effect of the transition with the shaped bead is less than, and is preferably no greater than half, the effect of a similar transition in impedance with no bead at all.
  • Figure 1 is a side view, partly in section, of a cable, shroud, and sintering head ready for forming of one end of the cable.
  • Figure 2 is a view similar to Figure 1, showing the shroud in position on the cable.
  • Figure 3 is a view similar to Figure 2, showing the sintering head engaging the end of the cable.
  • Figure 4A is a view similar to Figure 3, showing a later stage of the forming process
  • Figure 4B is an enlarged view of the detail within the circle marked "Fig. 4B" in Figure 4A.
  • Figure 5A is a view similar to Figure 4A, showing a final stage of the forming process.
  • Figure 5B is an enlarged view of the detail within the circle marked "Fig. 5B" in Figure 5A.
  • Figure 6A is a view similar to Figure 5A, showing the formed cable removed from the sintering head.
  • Figure 6B is an enlarged view of the detail within the circle marked "Fig. 6B" in Figure 6A.
  • Figure 7 is a view in longitudinal section of a coaxial cable connector fitted onto a cable formed as shown in Figures 1 to 6.
  • Figure 8 is an enlarged view of the detail within the circle marked "Fig. 8" in Figure 7.
  • the cable 10 consists essentially of a center conductor 12 of metal wire, a dielectric spacer 14 of several layers of helically wound or extruded ePTFE tape, an outer conductor 16 of metal braid, and a protective jacket 18.
  • each layer is cut back to provide a clean end square to the length of the cable, and to expose a length of the layer within it.
  • the braid 16 is stripped back to expose a substantial length of the ePTFE.
  • a ceramic shroud indicated generally by the reference numeral 20 is slid over the prepared end of the cable 10.
  • the main body of the shroud 20 consists of a cylindrical tube 22 that fits easily over the exposed braid 16.
  • a shoulder 24 that fits more closely over the exposed braid 16, to ensure accurate centering of the shroud on the cable.
  • a lip 26 that extends radially inward far enough to overlap the braid 16.
  • the lip 26 does not extend far enough to contact the exposed dielectric 14, but rather leaves a substantial radial gap 28.
  • the radial width of the gap 28 is normally at least 2% of the diameter of the braid 16.
  • the shroud 20 is positioned so that the lip 28 abuts the cut end of the braid 16.
  • a sintering head indicated generally by the reference numeral 30, consists largely of a cylindrical block of titanium with a heating element (not shown).
  • the sintering head 30 has in one end a blind bore 32 that is of a suitable diameter to fit snugly over the exposed dielectric 14 of the cable 10. The depth of the bore 32 is approximately half the exposed length of the dielectric 14.
  • the sintering head 30 also has an axial through bore 34, sufficiently wide to receive the center conductor 12 of the cable 10.
  • a firing pin 36 is received in a radial bore in the sintering head 30, and can be advanced to a position where it clamps the center conductor 12, if the conductor is present in the bore 34.
  • the sintering head 30 is preheated to a temperature of at least 375 °C (700 °F), and not more than 540 °C (1000 °F). As shown in Figure 3, the sintering head 30 is initially placed on the end of the cable 10 so that the cut end of the dielectric 14 abuts the bottom of the blind bore 32, and the tip of the center conductor 12 fits into the through bore 34.
  • the sintering head 30 is then forced onto the end of the cable 10, compressing the dielectric 14.
  • the cable 10 is gripped by at least one cable grip 35, which is set back at least 7 mm (0.25") from the exposed braid 16.
  • the braid 16 fits over the dielectric 14 with sufficient tension to prevent the dielectric from being forced into the braid by the sintering head 30.
  • the sintering head is advanced until it contacts the lip 26 of the shroud 20, as shown in Figure 4B.
  • the gap 28 is now a closed, annular space, axially between the braid 16 and the sintering head 30, and radially between the dielectric 14 and the lip 26.
  • the sintering head 30 is then clamped in place by tightening the firing pin 36 onto the center conductor 12. This also ensures good thermal contact between the sintering head 30 and the center conductor 12.
  • the ePTFE forms a continuous mass 42.
  • the ePTFE expands, filling the interior of the blind bore 34 within the sintering head. As the ePTFE presses against the surface of the blind bore, good heat transfer is ensured.
  • the ePTFE then flows into the gap 28 to form a bead 40, shown in Figure 5B.
  • the time for which the sintering head is left heated on the cable depends on the cable type, but is typically between 20 seconds and 3 minutes.
  • the bead 28 does not fill the gap 28, but an air space is left outside it. This permits solder to flow completely around the circumference of the braid, so that a good solder fill can be obtained.
  • the heat also erases any memory of previous shapes from the PTFE, ensuring that the bead will be permanent.
  • the whole assembly is then allowed to cool, and the titanium sintering head 30 and the ceramic shroud 20 are then removed from the cable.
  • the sintered PTFE mass 42 shrinks, but the bead 40 is still large enough to lock on the end of the braid.
  • the braid is not embedded within the sintered PTFE, but the bead is too wide to slip inside the braid.
  • the bead 40 may be shaped, as shown in Figure 6B, by providing a bevel 44 on the lip of the bore 32 in the sintering head 30, as shown in Figure 6A.
  • the sintering of the ePTFE does, of course, alter the dielectric constant.
  • dielectric constant there is a fairly sudden change in dielectric constant between the sintered ePTFE 42 of the endpiece and the only partially sintered ePTFE 14 within the braid 16. That change occurs approximately at the level of the bead 40, and can be compensated for by shaping the bead and/or by shaping the inside of a metal cable connector where it fits over the bead.
  • the transition between partially-sintered and unsintered ePTFE 14 within the braid 16 is sufficiently gradual not to cause a serious effect on microwave transmission.
  • the sintered ePTFE 42 of the endpiece may also be shaped for optimal fitting, both mechanical and electrical, into a connector.
  • a conventional coaxial cable connector is shown mounted on the end of the cable 10.
  • a sleeve 52 of the connector 50 is mounted on the cable 10, covering the exposed portion of the braid 16 and the end of the jacket 18.
  • the sleeve 52 is secured mechanically and electrically to the braid 16 by soldering.
  • a collar 54, with an external screw thread, is captive behind a shoulder 56 on the sleeve 52.
  • a metal connector pin 58 fits over the exposed end of the center conductor 12 of the cable 10, and forms the center pin of the connector 50.
  • the pin 58 is captive behind a shoulder on an insulating sleeve 60, which is captive behind a shoulder on an internally screw-threaded sleeve 62, which is screwed onto the collar 54.
  • An internally screw-threaded collar 64 which forms the outer connection component of the connector 50, is held captive, but free to rotate, on the sleeve 62 by means of a spring ring 64.
  • the bead 40 and therefore the transition from sintered dielectric 42 to only partially sintered dielectric 14, is aligned with the transition between the braid 16 and the connector sleeve 52.
  • the bead 40 is machined to a profile that compensates for the transitions in the other components, so as to afford as nearly as possible an unimpeded propagation of the microwave signals along the cable 10 and through the connector 50.
EP00308800A 2000-01-19 2000-10-05 Câble coaxial ainsi que procédé et dispositif de formation Withdrawn EP1119079A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US48753900A 2000-01-19 2000-01-19
US487539 2000-01-19

Publications (1)

Publication Number Publication Date
EP1119079A1 true EP1119079A1 (fr) 2001-07-25

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP00308800A Withdrawn EP1119079A1 (fr) 2000-01-19 2000-10-05 Câble coaxial ainsi que procédé et dispositif de formation

Country Status (3)

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EP (1) EP1119079A1 (fr)
JP (1) JP2001238323A (fr)
CA (1) CA2325208A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8800135B2 (en) * 2006-06-27 2014-08-12 Scientific-Atlanta, Inc. Stinger cutting guide

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113488297B (zh) * 2021-07-08 2022-10-04 萍乡强盛电瓷制造有限公司 一种高强度悬式瓷绝缘子及其加工方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3437960A (en) * 1966-03-30 1969-04-08 Amp Inc Dielectric bead structure for coaxial connectors

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3437960A (en) * 1966-03-30 1969-04-08 Amp Inc Dielectric bead structure for coaxial connectors

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8800135B2 (en) * 2006-06-27 2014-08-12 Scientific-Atlanta, Inc. Stinger cutting guide

Also Published As

Publication number Publication date
CA2325208A1 (fr) 2001-07-19
JP2001238323A (ja) 2001-08-31

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