GB2182325A - An improved optical fibre cutting tool - Google Patents

Abstract

To reduce risk of injury to an operator by, or risk of damage to, the elongate cutter 28 of a hand tool of known form for cutting an optical fibre or an optical fibre ribbon, the hand tool includes, on opposite sides and extending throughout the length of the elongate cutter 28, walls 43 which, when operation of the tool is not being effected, project beyond and shield the rectilinear cutting edge 30 of the cutter. When the handles 1,2 and 3 of the tool are urged together against the action of associated spring means 37 to actuate the tool, the walls 43 retract with respect to the cutting edge 30 to permit the cutting edge to effect a rectilinear score in the or each optical fibre. <IMAGE>

Description

SPECIFICATION An improved optical fibre cutting tool In effecting a splice orjoint between two optical fibres or between the optical fibres of two optical fibre ribbons, in orderto ensure optimum lightcoupling efficiency or, in otherwords,to keep light losses at the splice or joint as low as possible, it is desirable that the neighbouring end faces of the optical fibres to be spliced orjointed be substantially flat and lie in planes radial to the axes of the fibres.

For effecting a rectilinear score across an optical fibre or across each of a plurality of optical fibres substantially normal to the axis of the optical fibre in order to provide on the optical fibre an end face which is substantially flat and lies in a plane radial to the axis of the fibre.It has been proposed to provide a hand tool comprising at least two members interconnected in such a way that at least one of the members is constrained to move in a direction towards or awayfrom the other member or members and is urged away from the other member or members by associated spring means; a table having a smooth surface carried on one ofthe membersforsupporting the optical fibre orthe plurality of optical fibres; an elongate cutter which is associated with the table and is mounted on the other or another ofthe membersandwhich hasa rectilinearcutting edge; and clamping means and associated guide means four clamping an optical fibre our a plurality of optical fibres so that the or each optical fibre is supported on said substantially smooth surface with the axis ofthe optical fibre substantially normal to the rectilinear cutting edge of the elongate cutter, the arrangement being such that, when the member or members is or are moved in a direction towards the other member or members against the action of said associated spring means, the rectilinear cutting edge ofthe cutter will effect a rectilinear score across the or each optical fibre substantially normal to the axis ofthe optical fibre. A hand tool ofthis kind will hereinafter,forconvenience, be referred to as a hand tool ofthe kind described.

The elongate cutter of the hand tool of the kind described is generally a diamond having a rectilinear cutting edge and this cutting edge is extremely sharp and dangerous if there is any riskthat it should come into contact with a finger or hand an operator.

Furthermore, the cost of a diamond cutter constitutes a substantial proportion of the overall cost of a hand tool ofthe kind described and damageto the re ctilinearcutting edgeofthediamondcuttershould be avoided if at all possible.

It is an object ofthe present invention to provide an improved hand tool of the kind described wherein riskofinjuryto an operator by, or riskofdamageto, the elongate cutter is substantially reduced.

According to the invention, the hand tool of the kind described also includes, on opposite sides and extending throughoutthe length of the elongate cut ter,wallswhich,when operation ofthe hand tool is not being effected, project beyond and shield the rectilinear cutting edge of the cutter and which, when the memberor members ofthe hand tool is rare urged towardsthe other memberor members against the action of the associated spring means, will retract with respect to the cutting edge to permit the cutting edge to effect a rectilinear score in the or each optical fibre.

Where, as is preferred, the hand tool comprises at least two elongate members extending side by side and pivotally connected together near one of their neighbouring ends about an axis or axes transverse tothe members,thetable and clamping means and associated guide means being mounted on one elongate member at a position remote from the pivotal axis or axes and the elongate cutter being mounted on the other or another elongate member at a position remote from the pivotal axis or axes, preferably remote from the pivotal axis or axes, preferably the walls shielding the rectilinear cutting edge ofthe cutter are pivotally mounted about an axis transverse to the members on the elongate member carrying the elongate cutter, or on another elongate member which is urged by associated spring means away from the elongate memberon which thetable is mounted, andthewalls are urged ina directiontowards the table by a spring, the arrangement being such that, when pivotal movement ofthe elongate member carrying the elongate cutter is effected against the action of said associated spring means, the walls engage an abutment directly or indirectly carried by the elongate member on which the table is mounted to arrest pivotal movement of the walls without arresting pivotal movement of the elongate member carrying the elongate cutter so that, in effect, the walls retract with respect to the cutter to expose the cutting edge and permit it to effect a re ctilinear score in the or each optical fibre. In this arrangement, preferably the walls are integral with or are secured to the free end of a supplementary elongate member extending alongside the elongate member carrying the elongate cutteroralongside said other elongate member and pivotally connected thereto at a position remote from the elongate cutter.

In a preferred embodiment, the longitudinally ex- tending edges ofthe walls nearer the smooth surface ofthe table are joined by a transversely extending wall in which isawindowthroughwhichtheelongate cutter will protrude when the walls are caused to retract with respect to the cutter. The ends ofthe walls nearer the elongate cutter may extend beyond the elongate cutter and may be interconnected by a transversely extending end wall which projects beyond the rectilinear cutting edge of the elongate cutter so that, when operation of the hand tool is not being effected, the elongate cutter is protected by a th ree-sided shroud having an apertured base wall.

The present invention is especially, but not exclusively, applicable to the hand tool for effecting a transverse score in each optical fibre of an optical fibre ribbon as described and claimed in the specification of our co-pending British PatentApplication No: 8430922.

The invention is further ililustrated by a description, by way of example, the preferred hand tool for effecting a transverse score in each optical fibre of an optical fibre ribbon, with reference to the ac companying drawings, in which: Figure lisa sectional view of the hand tool shown with the rectilinear cutting edge ofthe elongate cutter in the position it will be when effecting a rectilinear score in each optical fibre, and Figure2 is a front end view ofthetool.

Referring to the drawings, the improved hand tool comprises three elongate members 1,2and3exten- ding side by side and interconnected near one of their neighbouring ends by an end wall 4. One outer elongate member 1 is fixed to the end wall 4 and the other outer elongate member 3, which is of inverted chennel-shaped cross-section, is pivotally connected to the end wall about an axis 5 transverse to the members.

Atthe end of the outer elongate member 1 remote from the end wall 4 is an arm 6which extends laterally on opposite sides of the member and which has an upper smooth flat surface 7. Mounted on the laterally extending arm 6 on opposite sides of the central transverse axis ofthe arm are clamping means 9for clamping on optical fibre ribbon on the smooth surface 7 ofthe arm. The clamping means 9 comprises a pivotally mounted lever mechanism 10 which can be snapped into the closed or clamping position and which has a pad 11 of rubber-like material of about 60 shore hardness and the smooth flat surface 7 ofthe laterally extending arm 6, the pad serving to clamp an optical fibre againstthe smooth surface ofthe arm.Atable 12 which has a smooth surface 14 of convex form of rubber-like material, the centres of curvature ofthe convex surface lying in an axis normal to the pivotal axis 5 of the elongate member 3, isslidably mounted in a chamber 15 extending through and opening into the uppersurface7 ofthe arm 6 between the clamping means 9 and is urged awayfrom the clamping means buy a coil spring 16.

The chamber 15 also opens into the undersurface 17 ofthe arm 6 to provide, as will be explained, for movement of the table 12 with respect to the clamping means 9.

Adjacent each clamping means 9 on the uppersurface 7 ofthe laterally extending arm 6 is a step 19 which extends normally to the axis of the centres of curvature of the convexly curved smooth surface 14 ofthe table 12 and whose riser constitutes guide meansforan optical fibre ribbon.

The elongate member 2 is pivotally connected to the end wall 4 about axis 5 and, between its ends, the elongate member is connected to the outer elongate member 3 by a screw 21 which depends from the member 3, passes through a hole 22 in the member2 and which, on the side of the member 2 remote from the member 3, carries a coil spring 23 positioned be tween the member 2 and a nut24,which spring urges the member 2 towards the member 3. Pivotal move mentofthe elongate member2 is restrained bya leaf spring 26 which is secured to the member and which bears against the end wall 4. At the end ofthe elongate member 2 remote from the end wall 4, the member carries an elongate cutter 28 which is resiliently mounted on the member by means of a leaf spring 29.The elongate cutter 28 has a rectilinear cutting edge 30 which is parallel to the axis of the centres of curvature ofthe curved smooth surface 14 of the table 12 and which is normal to the pivotal axis 5 of the elongate member2. Secured to the elongate member2 near its free end remotefrom the end wall 4 by means of a screw 32 is a button 31 which protrudes through an aperture 33 in the outer elongate member3.The elongate member 2 us urged away from the fixed elongate member 1 by a coil spring 37 bounding an adjustable screw 36 which upstands from the elongate member 1 and whose head protrudes into a hole 38 in the elongate member 2. Foradjusting, within a limited range, the depth of the rectilinear score which the rectilinear cutting edge 30 of the cutter 28 will effect across each optical fibre ribbon, an adjustable screw 34 is carried by the elongate member 1 and constitutes an abutment againstwhich the screw 32 will abutwhentheel- ongate member is caused to pivot about the axis 5 against the action of the coil spring 37 by depression of the button 31.

Pivotally mounted between the side walls of the inverted channel-shaped elongate member 3 about an axis 42 is a supplementary elongate member 41 having a pairofsidewalls43which, atthefree end ofthe member remote from its pivotal axis, are positioned on opposite sides ofthe elongate cutter 28 and, when operation of the hand tool is not being effected, projectbeyond and shield the rectilinearcutting edge30 of the cutter. The lower longitudinally extending edges of those parts ofthe walls 43 overlying the arm 6 are joined by a transversely extending base wall 44 in which is a window 45. As has been explained, the elongate member 2 is urged towards the outer el ongate member 3 by coil spring 23 which boundsthe screw 21 and is positioned between the member 2 and a nut 24.The supplementary elongate member 41 is urged away from the elongate member 2 by a coil spring 47which bounds the coil spring 23 and which is positioned between the elongate member 2 and a plate 48 joining the lower longitudinally exten ding edgesofthesidewalls43.

When the hand tool istobeemployedtoeffecta rectilinear score across each optical fibre of an optical fibre ribbon ofthe kind described, any plastics covering on the fibres over a part of their lengths adjacent theirfree ends is removed and the optical fibre ribbon is positioned on the upper flat surface 7 ofthe arm 6 against one ofthe risers 19 constituting the guide means so that the stripped optical fibres lie side-by-side acrosstheconvexly curved uppersur- face 14 ofthe table 12. The lever mechanism 10 ofthe clamping means 9 adjacent the riser 19 is then snapped into the clamping position to clamp the optical fibre ribbon to the surface 7 of the arm 6 by the resilient pad 11. The button 31 is then depressed against the action of the spring 37 to cause the elongate member 2 and the supplementary elongate member 41 to pivot about the pivotal axes 5 and 42 with respect to the rigid elongate arm 1. When the base wall 44 of the supplementary elongate member 41 abuts the upper surface of the step 19, as shown in the drawings pivotal movement of the supplementary member is arrested and further pivotal movement of the elongate member 2 causes the elongate cutter 28 to pass through the window 45 in the supplementary member and to effect a rectilinear score across each optical fibre ofthe optical fibre ribbon. The pressure.on the button 31 is then released and the elongate member 2 and supple mentary member 41 return to their normal positions underthe actions of their associated springs 37 and 47.

Manual pressure is then applied to the under- surface 40 of the table 12, which is exposed in the opening ofthe chamber 15 in the undersurface 17 of the laterally extending arm 6,to causethetableto move towards the clamping means9to bendthe transversely scored optical fibres of the optical fibre ribbon about an axis normal to the axes ofthe optical fibres to cause them to cleave so that the optical fibres of the ribbon have end faces which are flat and lie in a common plane radial to the axes of the optical fibres.

Claims (6)

1. A hand tool for effecting a rectilinear score ac- ross an optical fibre across each of a plurality of optical fibres substantially normal to the axis of the optical fibre, which hand tool comprises at least two members interconnected in such a waythatat least one ofthe members is constrained to move in a direction towards or away from the other member or members and is urged away from the other member or members by associated spring means; a table having a smooth surface carried on one end ofthe membersforsupporting the optical fibreorthe plurality of optical fibres; an elongatecutterwhich is associated with the table and is mounted on the other or another ofthe members and which has a rectilinear cutting edge; and clamping means and associated guide means for clamping an optical fibre or a plurality of optical fibres so that the or each optical fibre is supported on said substantially smooth surface with the axis ofthe optical fibre substantially normal to the rectilinear cutting edge ofthe elongate cutter, the arrangement being such that, when the member or members is or are moved in a direction towards the other member or members are moved in a direction towards the other member or members againstthe action of said associated spring means, the rectilinear cutting edge ofthe cutterwill effect a rectilinear score across the or each optical fibre substantially normal to the axis of the optical fibre, and wherein the hand tool also includes, on opposite sides and extending throughoutthe length ofthe elongate cutter, walls which, when operation of the hand tool is not being effected, project beyond and shield the rectilinear cutting edge ofthe cutter and which, when the member or members ofthe hand tool is or are urged towards the other member or members against the action ofthe associated spring means, will retract with respect to the cutting edge to permit the cutting edge to effect a rectilinear score in the or each optical fibre.

2. A hand tool as claimed in Claim 1 in which at least two elongate members extend side by side and are pivotally connected together one oftheir neighbouring ends about an axis or axes transverse to the members, the table and clamping means and associated guide means being mounted on one elongate member at a position remote from the pivotal axis or axes and the elongate cutter being mounted on the other or another elongate member at a position remote from the pivotal axis or axes, wherein the walls shielding the rectilinear cutting edge ofthe cutter are pivotally mounted about an axis transverse to the members on the elongate member carrying the elongate cutter, or on another elongate member which is urged by associated spring means away from the elongate memberon which thetable is mounted, and the walls are urged in a direction towards the table by a spring, the arrangement being such that, when pivotal movement ofthe elongate member carrying the elongate cutter is effected against the action of said associated spring means, the walls engage an abutment directly or indirectly carried by the elongate member on which the table is mounted to arrest pivotal movement of the walls without arresting pivotal movement of the elongate member carrying the elongate cutter so that, in effect the walls retract with respect to the cutter to expose the cutting edge and permit it to effect a rectilinear score in the or each optical fibre.

3. A hand tool as claimed in Claim 2, wherein the walls are integral with or are secured to the free end of a supplementary elongate member extending alongside the elongate member carrying the elongate cutter or alongside said other elongate member and pivotally connected thereto at a position remote from the elongate cutter.

4. A hand tool as claimed in any one of the pre- ceding Claims, wherein the longitudinaliy extending edges of the walls nearerthe substantially smooth surface ofthe table are joined by a transversely extending wall in which is a window th rough which the elongate cutterwill protrude when the walls are caused to retract with respect to the cutter.

5. A hand tool as claimed in Claim 4, wherein the ends ofthe walls nearerthe elongate cutter extend beyond the elongate cutter and are interconnected by a transversely extending end wall which projects beyond the rectilinear cutting edge of the elongate cutter so that, when operation of the hand tool is not being effected, the elongate cutter is projected by a three-sided shroud having an apertured base wall.

6. A hand tool of the kind described substantially as hereinbefore described with reference to and as shown in the accompanying drawings.