GB2168641A

GB2168641A - Cutting optical fibre ribbon

Info

Publication number: GB2168641A
Application number: GB08530187A
Authority: GB
Inventors: Edward Zbigniew Kaczmarski; Stuart Lester Ralph
Original assignee: BICC PLC
Current assignee: Balfour Beatty PLC
Priority date: 1984-12-07
Filing date: 1985-12-06
Publication date: 1986-06-25
Also published as: GB8530187D0; GB8430917D0; GB2168641B

Abstract

A hand tool for bending an optical fibre ribbon about an axis extending normal to the axes of the optical fibres comprises a pair of spring loaded handles 1,2 having a pair of co-operating jaws 5, 6 at adjacent ends. One jaw 5 has a smooth convex surface 7 whose centres of curvature lie on an axis normal to the pivotal axis 3 of the handles 1, 2 and the other jaw 6 has a smooth concave surface 8 of complementary shape. An optical fibre ribbon which has had a rectilinear cut normal to the axes of the optical fibres effected across the ribbon to a depth sufficient to effect a transverse score in each optical fibre, is inserted between the jaws with the optical fibres normal to the axis containing the centres of curvature of the convex surface and the handles 1, 2 are caused to pivot against the spring to bend the optical fibre ribbon between the jaws so that the optical fibres cleave along the scores to form on the fibres flat end faces which lie in a common plane perpendicular to the axes of the fibres. <IMAGE>

Description

SPECIFICATION Cutting optical fibre ribbon This invention relates to optical fibre ribbon of the kind comprising a plurality of optical fibres arranged side by side with their axes lying in a substantially common plane and embedded in an elongate body of plastics material.

When effecting a splice between optical fibres of an optical fibre ribbon of this kind and optical fibres of another optical fibre rib bon of the same kind, in order to ensure opti mum light coupling efficiency in each optical fibre joint or, in other words to keep light losses at each joint as low as possible, it is desirable that the end faces of each pair of optical fibres to be jointed be substantially flat 'and lie in planes radial to the axes of the fibres and that end faces of the optical fibres of each optical fibre ribbon lie in a substan tially common plane.

In the specification of our co-pending Patent Application No: 84/30922 there is described and claimed an improved method of providing optical fibres of an optical fibre ribbon of the kind described with end faces that are sub stantially flat and lie in a substantially common plane radial to the axes of the fibres.This improved method comprises supporting a length of optical fibre ribbon on a substantially smooth surface; effecting a rectilinear cut sub stantially normal to the axes of the optical fibres across the whole transverse width of the optical fibre ribbon to a depth sufficient to effect a transverse score in each optical fibre; and thereafter bending the optical fibre ribbon about an axis extending substantially normal to the axes of the optical fibres to such an extent that the fibres of the ribbon cleave to form on the fibres end faces which are sub stantially flat and lie in a substantially common plane radial to the axes of the fibres.

It is an object of the present invention to provide, for use in the improved method of the aforesaid co-pending patent application, an improved hand tool for bending an optical fibre ribbon of the kind described about an axis extending substantially normal to the axes of the optical fibres.

According to the invention the improved hand tool comprises a pair of elongate mem bers arranged side by side and so pivotally connected together about an axis extending transversely of the members that adjacent ends of the members are urged apart by spring means carried by the members, and a pair of co-operating jaws carried by the mem bers at said adjacent ends, one of which jaws has a smooth, convex surface whose centres of curvature lie on an axis extending substantially normal to the pivotal axis of the elongate members and the other of which jaws has a smooth, concave surface which is of comple mentary shape to the convex surface of said first jaw, the arrangement being such that when an optical fibre ribbon of the kind described, which has had a rectilinear cut substantially normal to the axes of the optical fibres effected across the whole transverse width of the optical fibre ribbon to a depth sufficient to effect a transverse score in each optical fibre, is inserted between the jaws with the optical fibres substantially normal to the axis of the centres of curvature of said convex surface and the elongate members are caused to pivot against the action of said spring means to close the jaws and bend the optical fibre ribbon between the co-operating curved surfaces of the jaws, the optical fibres of the ribbon will cleave along said scores to form on the fibres end faces which are substantially flat and lie in a substantially common plane radial to the axes of the fibres.

In a preferred method of using the improved hand tool, the optical fibre ribbon is so inserted between the jaws that the position on the ribbon at which the fibres are scored is just outside or just inside the co-operating curved surfaces of the jaws and as or when the jaws are closed, the scored part of the ribbon is drawn in the direction of length of the ribbon between the co-operating curved surfaces of the jaws to cause the optical fibres to cleave along the scores by a combination of bending of, and tension applied to, the ribbon.

Preferably, one or each of the co-operating curved surfaces of the jaws has guide means for so orientating an optical fibre ribbon when it is inserted between the jaws that the axes of the optical fibres of the ribbon are substan tiaily normal to the axes common to the centres of curvature of the curved surfaces of the jaws.

The guide means preferably takes the form of a step in the convex surface, the riser of the step extending substantially normal to the axes common to the centres of curvature of the convex surface.

Preferably, also, one or each of the co-operating curved surfaces of the jaws carries a layer of readily compressible material, for example, rubber or plastics foam.

In a preferred embodiment, the elongate member carrying at one of its ends the jaw with a smooth, convex surface is substantially straight and the other elongate member carrying at one of its ends the jaw with a smooth, concave surface is of approximately "dog-leg" shape, the pivotally connected members being urged apart by a coil spring.

Preferably, the co-operating convex and concave surfaces of the jaws each has a radius lying in the range 10 to 30 millimetres and each preferably subtends an angle lying in the range 80 to 100 .

The invention is further illustrated by a description, by way of example, of a preferred hand tool for bending an optical fibre ribbon of the kind described about an axis extending substantially normal to the axes of the optical fibres, with reference to the accompanying drawings, in which: Figure 1 is a side view, partly in section and partly in elevation, of the hand tool; Figure 2 is a view of the hand tool in the direction of arrow A with one of two handles of the tool omitted, and Figure 3 is a front end view of the hand tool.

Referring to the drawing, the preferred hand tool comprises a pair of elongate handles 1, 2 arranged side by side and pivotally connected together at a position 3 intermediate of their ends about an axis extending transversely of the handles. The handle 1 is substantially straight and over a part of its length to one side of the pivotal axis 3 is of inverted substantially U-shaped transverse cross-section and the handle 2 is of approximately "dogleg" shape with the pivotal axis 3 passing through the intermediate part of the "dog leg".

Adjacent ends of the handles 1, 2 are urged apart by a coil spring 4 interconnected between the inverted-U-shaped part of the handle 1 and the neighbouring part of the handle 2. At adjacent ends of the handles 1, 2 on the opposite side of the pivotal axis 3 to the coil spring 4, the handles carry a pair of co-operating jaws 5, 6. The jaw 5 carried by the handle 1 has a smooth convex surface 7 whose centres of curvature lie on an axis extending substantially normal to the pivotal axis 3; the other jaw 6 has a smooth concave surface 8 which is of complementary shape to the convex surface 7. The convex surface 7 carries a layer 9 of readily compressible rubber and the concave surface 8 carries a layer 10 of readily compressible rubber.

In use, an optical fibre ribbon of the kind described, which has had a rectilinear cut substantially normal to the axes of the optical fibres effected across the whole transverse width of the optical fibre ribbon to a depth sufficient to effect a transverse score in each optical fibre, is so inserted between the jaws with the optical fibres substantially normal to the axis of the centres of curvature of the convex surface 7 that the position on the ribbon at which the fibres are scored is just outside or just inside the co-operating convex and concave curved surfaces 7, 8 of the jaws.

As or when the handles 1, 2 are caused to pivot against the action of the coil spring 4 to close the jaws, the scored part of the ribbon is drawn in the direction of length of the ribbon between the co-operating curved surfaces 7, 8 to cause the optical fibres to cleave along the scores by a combination of bending of, and tension applied to, the ribbon to form on the fibres, end faces which are substantially flat and lie in a substantially common plane radial to the axes of the fibres.

Claims

1. A hand tool for bending an optical fibre ribbon of the kind described about an axis extending substantially normal to the axes of the optical fibres, which hand tool comprises a pair of elongate members arranged side by side and so pivotally connected together about an axis extending transversely of the members that adjacent ends of the members are urged apart by spring means carried by the members, and a pair of co-operating jaws carried by the members at said adjacent ends, one of which jaws has a smooth, convex surface whose centres of curvature lie on an axis extending substantially normal to the pivotal axis of the elongate members and the other of which jaws has a smooth, concave surface which is of complementary shape to the convex surface of said first jaw, the arrangement being such that when an optical fibre ribbon of the kind described, which has had a rectilinear cut substantially normal to the axes of the optical fibres effected across the whole transverse width of the optical fibre ribbon to a depth sufficient to effect a transverse score in each optical fibre, is inserted between the jaws with the optical fibres substantially normal to the axis of the centres of curvature of said smooth convex surface and the elongate members are caused to pivot against the action of said spring means to close the jaws and bend the optical fibre ribbon between the co-operating curved surfaces of the jaws, the optical fibres of the ribbon will cleave along said scores to form on the fibres end faces which are substantially flat and lie in a substantially common plane radial to the axes of the fibres.

2. A hand tool as claimed in Claim 1, wherein one or each of the co-operating curved surfaces of the jaws has guide means for so orientating an optical fibre ribbon when it is inserted between the jaws that the axes of the optical fibres of the ribbon are substantially normal to the axes common to the centres of curvature of the curved surfaces of the jaws.

3. A hand tool as claimed in Claim 2, wherein the guide means is a step in the convex surface, the riser of the step extending substantially normal to the axes common to the centres of curvature of the convex surface.

4. A hand tool as claimed in any one of the preceding Claims, wherein one or each of the co-operating curved surfaces of the jaws carries a layer of readily compressible material.

5. A hand tool as claimed in any one of the preceding Claims, wherein the elongate member carrying at one of its ends the jaw with a smooth, convex surface is substantially straight and the other elongate member carrying at one of its ends the jaw with a smooth, concave surface is of approximately "dog-leg" shape, the pivotally connected members being urged apart by a coil spring.

6. A hand tool as claimed in any one of the preceding Claims, wherein the co-operating convex and concave surfaces of the jaws each has a radius lying in the range 10 to 30 mm and each subtends an angle lying in the range 80 to 100 .

7. A hand tool for bending an optical fibre ribbon of the kind described about an axis extending substantially normal to the axes of the optical fibres substantially as hereinbefore described with reference to and as shown in the accompanying drawings.