Western Electric Company, Inc.

Bell Telephone Laboratories

At&t Technologies, Inc.

Randy G Schneider

Alvin C Levy

Charles J Aloisio, Jr

George S Brockway

George M Yanizeski

William D Bohannon, Jr

Michael D Kinard

Herbert A Lord

A cable shielding method and apparatus are disclosed wherein adhesive 42 is applied to a strip 40 of shielding material within a shield forming die 20 as the strip 40 is being formed about a cable core 10 with an overlapped shield seam.

Cable shielding method and apparatus

A cable which is capable of being made in a large pair size and yet which has excellent mechanical properties that maintain its integrity notwithstanding extremes in temperature during installation and shipping as well as during the rigors of installation includes a sheath system having a corrugated steel outer shield that is adhesively bonded to a plastic jacket. The corrugated steel shield which is formed to have a longitudinal overlapped seam that is preferably unsealed encloses an aluminum inner shield that in turn encloses a multiconductor core. Advantageously, the sheath system includes a plastic jacketing material which is capable of resisting biaxial stresses which are aggravated in a bonded sheath system. This results in jacket integrity about the longitudinal seam of the outer shield notwithstanding a notched cross-section and an unsupported bridged portion of the plastic jacket adjacent to the seam. Of additional benefit is a further characterization of the plastic as being one which because of its relatively low elastic modulus at conventional extrusion times and temperatures is caused to fill substantially the corrugations of the outer shield. The jacket plastic forms a surface-to-surface bond with the shield that is sufficient to prevent delamination of the outer shield and the jacket and to prevent buckling of the jacket during exposure to temperature extremes.

Bonded sheath cable

A cable which is capable of being made in a large pair size and yet which has excellent mechanical properties that maintain its integrity notwithstanding extremes in temperature during installation and shipping as well as during the rigors of installation includes a sheath system having a corrugated steel outer shield that is adhesively bonded to a plastic jacket. The corrugated steel shield which is formed to have a longitudinal overlapped seam that is preferably unsealed encloses an aluminum inner shield that in turn encloses a multiconductor core. Advantageously, the sheath system includes a plastic jacketing material which is capable of resisting biaxial stresses which are aggravated in a bonded sheath system. This results in jacket integrity about the longitudinal seam of the outer shield notwithstanding a notched cross-section and an unsupported bridged portion of the plastic jacket adjacent to the seam. Of additional benefit is a further characterization of the plastic as being one which because of its relatively low elastic modulus at conventional extrusion times and temperatures is caused to substantially fill the corrugations of the outer shield. The jacket plastic forms a surface-to-surface bond with the shield that is sufficient to prevent delamination of the outer shield and the jacket and to prevent buckling of the jacket during exposure to temperature extremes.

Methods and apparatuses are disclosed for extruding tubular jackets of uniform radial thicknesses about cables employing a diverter tube assembly 10 that provides a divergent flow path for a plastic fluid from diametrically opposite channel orifices 46 to a tubular confluence. The diverter tube circumference is between 22 and 50 times the prespread width of each channel orifice while the axial to lateral spread ratio of the divergent flow path is between 1:2 tangent 30.degree. and 1:2 tangent 40.degree..

Method and apparatus for extruding tubular jackets

A waterproof shielded cable is disclosed having a metallic shield formed with a longitudinal seam surrounding a core. A strip of material overlays the metallic shield seam with side edges located to each side of the seam. An extruded plastic jacket overlays the metallic shield and strip of material with the jacket being in intimate contact with the shield and with a principle surface of the strip of material but spaced from the strip side edges. A method is also disclosed for manufacturing a shielded cable which comprises the step of wrapping sheet metal about a cable core with the sheet metal edges overlapped to form a shield with a longitudinal seam. The shield seam is overlayed with a strip of material of a type characterized by being shrinkable when heated above a predetermined temperature, and with the strip edges straddling the shield seam. A plastic jacket is extruded onto the shielded core and strip of material at a temperature in excess of the predetermined temperature. The plastic jacket is cooled by conducting heat from the jacket into an ambient cooling medium and into the core through the strip of material and shield whereupon the strip of material becomes heated and shrinks drawing the strip edges towards the shield seam to leave gaps bounded by the strip edges, the shield and the jacket. During formation the gaps are filled with a flooding compound having a lower thermal conductivity than the surrounding materials.

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Norcross, GA, United States of America

Randy G Schneider