Optical cable element manufacture
First Claim
1. A method of manufacturing an optical cable element comprising a tube of plastics material loosely housing at least one optical fibre, the space in the tube not occupied by the optical fibre or fibres being filled with a water-impermeable medium of a jelly-like nature, which method comprises initially causing at least one optical fibre to travel in a rectilinear direction in the direction of its length under a controlled tension through a substantially rigid capillary tube which extends through a chamber connected to the upstream end of extrusion apparatus and into said extrusion apparatus;
- introducing water-impermeable medium in a liquid state into said chamber at a substantially constant pressure head;
gradually withdrawing the capillary tube from the extrusion apparatus and chamber in an upstream direction so that water-impermeable medium is applied directly to the optical fibre being withdrawn through the chamber and that the advancing optical fibre with water-impermeable medium therearound passes directly from the chamber into the extrusion apparatus;
extruding a tube of polymeric material around the advancing optical fibre and the surrounding water-impermeable medium in such a way that the internal diameter of the tube is substantially greater than the overall diameter of the optical fibre;
drawing down the extruded tube of polymeric material to reduce its internal diameter to such an extent that the tube loosely envelopes the optical fibre with the space within the tube not occupied by the optical fibre substantially filled with water-impermeable medium of jelly-like nature and heating the extruded tube as it is being drawn down; and
annealing the drawn-down tube to reduce the risk of subsequent substantial shrinkage of the tube.
1 Assignment
0 Petitions
Accused Products
Abstract
In the manufacture of an optical cable element comprising a tube of plastics material loosely housing at least one optical fibre, a water-impermeable medium in a liquid or semi-liquid state is applied to an advancing optical fibre immediately upstream of an extruder in such a way and under such a pressure that the advancing optical fibre with water-impermeable medium therearound passes into the extruder. After a tube of polymeric material has been extruded around the advancing optical fibre and the surrounding water-impermeable medium in such a way that the internal diameter of the tube is greater than the overall diameter of the optical fibre and the extruded tube has been drawn down and so treated that the molecules are longitudinally oriented, the space in the tube not occupied by the optical fibre is filled with water-impermeable medium of a jelly-like nature.
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Citations
19 Claims
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1. A method of manufacturing an optical cable element comprising a tube of plastics material loosely housing at least one optical fibre, the space in the tube not occupied by the optical fibre or fibres being filled with a water-impermeable medium of a jelly-like nature, which method comprises initially causing at least one optical fibre to travel in a rectilinear direction in the direction of its length under a controlled tension through a substantially rigid capillary tube which extends through a chamber connected to the upstream end of extrusion apparatus and into said extrusion apparatus;
- introducing water-impermeable medium in a liquid state into said chamber at a substantially constant pressure head;
gradually withdrawing the capillary tube from the extrusion apparatus and chamber in an upstream direction so that water-impermeable medium is applied directly to the optical fibre being withdrawn through the chamber and that the advancing optical fibre with water-impermeable medium therearound passes directly from the chamber into the extrusion apparatus;
extruding a tube of polymeric material around the advancing optical fibre and the surrounding water-impermeable medium in such a way that the internal diameter of the tube is substantially greater than the overall diameter of the optical fibre;
drawing down the extruded tube of polymeric material to reduce its internal diameter to such an extent that the tube loosely envelopes the optical fibre with the space within the tube not occupied by the optical fibre substantially filled with water-impermeable medium of jelly-like nature and heating the extruded tube as it is being drawn down; and
annealing the drawn-down tube to reduce the risk of subsequent substantial shrinkage of the tube. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- introducing water-impermeable medium in a liquid state into said chamber at a substantially constant pressure head;
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14. Apparatus for use in the manufacture of an optical cable element, which apparatus comprises apparatus for extruding a tube of polymeric material;
- a chamber which is connected to the upstream end of the extrusion apparatus and which contains water-impermeable medium in a liquid state and at a substantially constant pressure head;
a substantially rigid capillary tube which extends through the chamber and into the extrusion apparatus and which is longitudinally moveable with respect to the chamber and extrusion apparatus;
means for causing at least one optical fibre to travel in a rectilinear direction in the direction of its length under a controlled tension through said capillary tube and into said extrusion apparatus;
means for withdrawing the capillary tube in an upstream direction so that the advancing optical fibre with water-impermeable medium therearound will pass directly from said chamber into the extrusion apparatus;
means, downstream of the extrusion apparatus, for drawing down an extruded tube of polymeric material to reduce its internal diameter to such an extent that the tube will loosely envelop an optical fibre with the space within the tube not occupied by the optical fibre substantially filled with water-impermeable medium of a jelly-like nature and means for heating the extruded tube; and
means for annealing the drawn-down tube to reduce the risk of subsequent substantial shrinkage of the tube. - View Dependent Claims (15, 16, 17, 18, 19)
- a chamber which is connected to the upstream end of the extrusion apparatus and which contains water-impermeable medium in a liquid state and at a substantially constant pressure head;
Specification