Adhesive bonding and miscellaneous chemical manufacture – Methods – Making electrical conductors of indefinite length
Patent
1980-01-10
1982-03-16
Massie, Jerome W.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Making electrical conductors of indefinite length
156 51, 156159, 156266, 156289, 1563045, 1563046, 1563082, 156581, 1565831, 156668, 156344, 228171, 228203, G03D 1504
Patent
active
043199380
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a method of butt-jointing metal tapes coated on one or both sides with a film of thermoplastic polymer material, as part of a process for manufacturing a composite product involving the continuous feeding of a tape of the metal coated with the thermoplastic polymer film. The problem of butt-jointing two tapes of this type arises in the manufacture of electrical cables comprising an axial conductor, a thick electrical insulator extruded over the conductor and an outer conductor or metal screen applied over the electrical insulator and in turn covered with an outer sheath of thermoplastic polymer material. The problem is of particular importance with regard to submarine telecommunications cables. The present invention is also concerned with a device for carrying out this method, providing a means of rapidly restoring the thermoplastic polymer film stripped away from the end sections of the tapes.
French Pat. Nos. 1 599 919 (Compagnie Generale d'Electricite) and 2 219 498 (the present applicant) refer to cables with a central load-carrying strand of steel wires covered with a copper tube constituting the axial conductor, in turn covered with polyethylene insulation, in turn covered by an outer conductor or screen comprising a tape of aluminium or another good electrical conductor folded around the insulation, at least one side of the tape being previously coated with a film of thermoplastic polymer material. The entire assembly receives an outer jacket of thermoplastic polymer material. The internal and/or external coating films on the outer conductor or screen are bonded to the insulation and the outer sheath, respectively.
This type of cable is commonly known to those skilled in the art as a "compact cable", and one design objective for this type of cable is to obtain a strong bond between the outer conductor or screen and the insulation and/or the outer sheath. The excellent mechanical properties of this type of cable mean that the thickness of the outer conductor or screen can be reduced to a value consistent with the maximum permissible attenuation per unit length. The thickness of the outer sheath may also be reduced.
Manufacturing continuous lengths of coaxial cable involves using a device storing a quantity of the tape from which the outer conductor or screen is made. As a general rule, the shaping of the tube for the outer conductor or screen and the extrusion of the outer sheath are carried out simultaneously. The tape is generally supplied on spools, and the unit length supplied is less than the unit cable length, which means that with the cable making machine running normally it is necessary to splice the end of a new spool to the end of the tape on the spent spool. This operation is commonly referred to as "butt-jointing". The butt-jointing of the tapes must be carried out with the machine in operation, as it is not possible to stop extruding the outer sheath and then resume operation without producing discontinuities inconsistent with the required quality of cable.
A device known as an "accumulator" is used to create a reserve of tape, by reeving the tape to form a number of loops. The accumulator is located between the feed spool and the tube-forming unit. This means that tape feed may be interrupted for the time taken to make the butt-joint without stopping the rest of the machine. Generally speaking, the accumulator holds a reserve of a few hundred meters of tape, the tube forming and extrusion operations proceeding at a rate of around ten meters per minute. This means that several tens of minutes are available for the butt-jointing to be carried out.
In the specific case of compact cables, to avoid local loss of the high mechanical strength of the conductor it is necessary to butt-joint the tape without deterioration in its adhesive qualities and without interrupting its electrical continuity. The latter requirement means that the butt-jointing of the metal proper must be carried out using hot welding, cold pressure welding, brazing or bonding using a conductiv
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Massie Jerome W.
Societe Anonyme dite: Les Cables de Lyons
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