Manufacture of multiconductor cables

Claim 3

A method as claimed in claim 1, wherein the sealing material in the storage vessel is maintained at a temperature just above that at which crystallization begins and is continuously pumped from the storage vessel and circulated around a ring main to one or more cable feeding stations located in the ring main:

Claim 4

A method as claimed in claim 2, in which the cable core is being manufactured by the conventional stranding process employing a stranding machine having at least one stranding head and associated closing die, wherein the sealing material is applied to the core at the closing die of each stranding head of the stranding machine.

Claim 5

A method as claimed in claim 3, in which the first layer of conductors of the cable core is laid up around a group of at least two conductors forming a core center, wherein sealing material at a temperature just above that at which crystallization begins is delivered through an applicator die at the point where the two conductors are brought together to form the core center.

Claim 6

A method as claimed in claim 2, wherein surplus material spewing in a liquid or semisolid state from an applicator die at each cable feeding station is returned to the storage vessel and is brought back to the requisite temperature.

Claim 7

A method as claimed in claim 2, wherein the sealing material is pumped around the ring main at a rate substantially exceeding the aggregate rate of flow of material from the cable feeding stations to the cable core.

Claim 8

A method as claimed in claim 1, wherein each of a plurality of cable feeding stations is fed with sealing material from a separate source of supply.

Claim 9

A method as claimed in claim 7, wherein surplus sealing material spewing in a liquid or semisolid state from an applicator die at each cable feeding station is returned to the storage vessel associated with the die and is brought back to the requisite temperature.

Claim 10

Apparatus for use in providing a cable core comprising a multiplicity of insulated conductors with a barrier of sealing material which will not drain under the influence of gravity or such hydrostatic pressure as may arise in the event of damage to the sheath of the cable but which will permit relative sliding movement of the insulated conductors over one another during such bending of the cable as occurs during manufacture and installation of the cable, which apparatus comprises: a. a thermostatically controlled storage vessel for storing the sealing material, b. means for maintaining the sealing material at a temperature just above that at which crystallization begins, c. at least one cable feeding station connected to the storage vessel, d. means at the feeding station for applying sealing material to the cable core, and e. connected between the storage vessel and the appliCator means of the cable feeding station, means for withdrawing sealing material from the storage vessel and for controlling the rate of delivery of the material to the applicator means.

Claim 11

Apparatus for use in providing a cable core comprising a multiplicity of insulated conductors with a barrier of sealing material which will not drain under the influence of gravity or such hydrostatic pressure as may arise in the event of damage to the sheath of the cable but which will permit relative sliding movement of the insulated conductors over one another during such bending of the cable as occurs during manufacture and installation of the cable, which apparatus comprises: a. a thermostatically controlled storage vessel for storing the sealing material, b. means for maintaining the sealing material at a temperature just above that at which crystallization begins, c. at least one cable feeding station connected to the storage vessel, d. means at the feeding station for applying sealing material to the cable core, and e. connected between the storage vessel and the appliCator means of the cable feeding station, means for withdrawing sealing material from the storage vessel and for controlling the rate of delivery of the material to the applicator means.

Claim 12

Apparatus as claimed in claim 9, wherein the thermostatically controlled storage vessel is connected to a ring main for the sealing material in which is connected means for continuously withdrawing sealing material from the storage vessel, driving it around the ring main and back into the vessel, and a cable feeding station is provided at at least one location in the ring main.

Claim 13

Apparatus as claimed in claim 10, wherein the means for controlling the rate of delivery of the material to the applicator means is a valve.

Claim 14

Apparatus as claimed in claim 10, wherein each of a plurality of applicator means has associated with it a heated tank for collecting surplus material spewing from the applicator means, a pipe extends from the collecting tank to the storage vessel, and a scavenge pump is provided for pumping the surplus material from the collecting tank back into the storage vessel.

Claim 15

Apparatus as claimed in claim 9, wherein each of a plurality of thermostatically controlled storage vessels is connected to a separate cable feeding station.

Claim 16

Apparatus as claimed in claim 13, wherein each means for withdrawing sealing material from the storage vessel and controlling its rate of delivery to the applicator means is a metering pump.

Claim 17

Apparatus as claimed in claim 13, wherein each storage vessel is so located with respect to the applicator means of its associated cable feeding station as to collect surplus material spewing from the applicator means.

Claim 18

Apparatus as claimed in claim 9, wherein the applicator means comprises a die which forms at least a part of the closing die of a stranding head of a stranding machine and which has a number of ports for entry of sealing material, which ports are distributed uniformly around the axis of the die and are inclined to it so as to impart to sealing material entering the die a component of movement in the same axial direction as the direction of travel of the cable core.