GB2229324A

GB2229324A - Wire stripping tool

Info

Publication number: GB2229324A
Application number: GB8901706A
Authority: GB
Inventors: Barry Peter Liversidge
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-01-26
Filing date: 1989-01-26
Publication date: 1990-09-19
Also published as: GB8901706D0

Abstract

A tool to remove the outer sheath of a cable has a body 10 provided with an aperture to receive the cable and a cutting blade 20. The tool gives two depths of cut according to the way the cable is inserted in it. The arms 12, 13 are forced apart when the cable is inserted in the aperture normal to the tool. Rotation of the tool around the cable (Figure 4) using finger- hole 24 produces a relatively shallow annular cut. A deeper longitudinal cut is made by inserting the cable between faces 17 and 18 (in the plane of the tool, Figure 5) and drawing the tool along the cable. The convex surfaces 17, 18 flex the cable and open the cut to facilitate removal of the sheath. Two blades may be provided and may be arcuate to give an initial circumferential cut so as to obviate rotating the tool. The blade may be mounted on a carrier moveable relative to the body. <IMAGE>

Description

WIRE STRIPPING TOOL This invention relates to a wire stripping tool that is to say, a tool adapted to assist the removal of an insulating layer from a cable or wire. The invention further relates to a method for removing an insulating layer from a cable or wire. In particular - though not exclusively - the tool of this invention is intended to assist the removal of an outer insulating sheath from an electrical cable consisting of one or more individually insulated conductors encased within such an outer sheath.

Many electrical cables are of a "double-insulated" construction - that is to say, one or more currentcarrying conductors are individually insulated, and the insulated conductors are then enclosed within an outer sheath also of an insulating material. Sometimes, one or more of the conductors within the outer sheath may not be individually insulated - for example, an earthing conductor may be provided and in certain types of cable this is not separately insulated; in other cables a relatively strong filament may be provided to support the weight of the cable when suspended between two points, which filament may be a conductor, optionally insulated.When a cable as has been described above is to be terminated, it is necessary first to remove a length of the outer sheath, to give access to the conductors therewithin; then the removal of their respective insulating layers may be performed to permit the subsequent electrical termination of those conductors. The satisfactory removal of the outer sheath is difficult to perform rapidly if all risk of damage to the insulation of the inner conductors is to be avoided. This is especially so in cases where the outer sheath bonds at least to some extent to the insulation of the conductors contained within the outer sheath, or where the outer sheath is made of a particularly tough or strong plastics material, such as may be encountered in the case of cables intended for external use.

One of the aims of the present invention is to provide a tool adapted to assist the removal of an outer sheath from a cable, so facilitating the subsequent electrical termination of the cable conductors.

According to one aspect of the present invention, there is provided a tool adapted to assist the removal of an outer sheath from a cable, which tool has a body provided with an aperture to receive the cable and a cutting blade mounted to project into the aperture, the tool being configured such that when a cable is located in the aperture and the tool is rotated thereabout, the cutting blade penetrates the outer sheath to a first depth, and when the tool is slid along the wire, the cutting blade then penetrates the outer sheath to a second depth, greater than said first depth of penetration.

A tool according to this first aspect of the present invention facilitates the removal of an outer sheath from a cable in that a single tool may be used firstly to make an annular cut around the outer sheath of the cable at the location back to which the sheath is to be removed, whereafter the same tool may make a lengthwise cut along the cable, from that annular cut to the cable free end. By making the annular cut to a shallower depth than the lengthwise cut, the likelihood of any damage to the insulating layers of the individual conductors within the outer sheath is minimised. If the cutting blade is pre-set so that the annular cut is to a depth less than the minimum wall thickness of the outer sheath, there will be no risk of injury to the insulation of the inner conductors whilst effecting the annular cut.

The cutting blade penetrates the sheath to a greater depth during the lengthwise cut (typically to a depth equal to the greatest wall thickness of the outer sheath), but because there is a natural tendency for the tip of the cutting blade to locate itself between the inner conductors during the lengthwise cutting action, there is only a minimal risk of damage to the insulation of the conductors, though removal of the sheath is greatly facilitated. As a consequence, in a preferred embodiment of tool of this invention, the depth of penetration of the cutting blade is pre-set to be not greater than the minimum wall thickness of the outer sheath for the case where the tool is rotated about the cable, but the depth of penetration of the cutting blade is pre-set substantially to sever the outer sheath when the tool is slid along the wire.

The tool may have a main body which supports the cutting blade in a relatively movable manner, the blade being shifted with respect to the tool depending upon the sense of movement of the tool with respect to the cable - i.e. either rotational or axial sliding movement. Such shifting movement of the blade may be automatic, by virtue of friction between the blade and the cable, such that the alignment of the blade with respect to the body is changed, causing the projection of the blade into the aperture also to be varied.

Alternatively, a manual control for the blade may be provided, to alter the projection of the blade into the aperture.

According to a second aspect of this invention, there is provided a tool adapted to assist the removal of an outer sheath from a cable, which tool has a body provided with a cable-receiving aperture having two principal axes disposed at an angle to one another, the aperture being configured to permit a cable to lie therewithin along either axis, and a cutting blade mounted on the body to project into the aperture to penetrate the outer sheath of a cable located therein and lying along either axis, the tool being rotatable about a cable located in the aperture and lying along one axis thereof, whereby the blade performs an annular cut into the outer sheath of the cable, and the tool being slidable along a cable when located in the aperture along the other axis thereof, whereby the cutting blade then performs a lengthwise cut along the cable.

Most preferably, the aperture is configured such that when a cable is located in the aperture, the tool may be turned with respect to the cable about an axis substantially intersecting that of the cable such that the tool may have the cable lying selectively along either principal axis of the aperture. Most preferably, the aperture is re-entrant about both of said principal axes, whereby a cable located within the aperture and lying along either one of said principal axes is restrained in the aperture along that axis, provided of course that the cable is of an appropriate size for that tool.

It is greatly preferred for the aperture to be configured such that when a cable lies along said one axis of the aperture the cutting blade penetrates the outer sheath of the cable to a first depth, but when the cable lies along said other axis of the aperture, the cutting blade then penetrates the outer sheath to a second, greater depth than said first depth. This may be achieved by having the two principal axes of the aperture arranged at an angle to one another in a nonintersecting manner, with said one axis further from the cutting edge of the cutting blade than said other axis.

The tool described above may be modified to have a pair of opposed blades which project into the aperture from opposed sides thereof. Thus, according to a further aspect of this invention, there is provided a tool adapted to assist the removal of an outer sheath from a cable, which tool has a body provided with a cable-receiving aperture and a pair of cutting blades arranged to project into the aperture from opposed sides thereof, the tool being provided with means to control the projection of the blades with respect to the sides of the aperture and said means being configured to cause the blades to penetrate a cable located in the aperture to a first depth when the blades are to cut in the circumferential direction of the sheath, and to penetrate the cable to a second depth greater than said first depth when the blades are to cut in the longitudinal direction of the sheath.

Said controlling means may comprise appropriately configured lands or other surfaces forming a part of the body and defining the apertures, as described above.

Alternatively, each blade may be mounted on a respective carrier which is mounted on the body for relative movement with respect thereto, whereby the depth of penetration of the carried blade may be controlled by moving the carrier with respect to the body. For example, each blade may project from a surface of its carrier having a pair of intersecting grooves either one of which may contact the cable, the blade being positioned in the intersecting region of the grooves and said controlling means being arranged to turn the carrier with respect to the body selectively to have the cable extending along either groove.

Experience has shown that even when the outer sheath of the cable is cut through for the entire length of that outer sheath which is to be removed, for certain types of cable the actual removal of the outer sheath still can be difficult. In an attempt to reduce this difficulty, yet another aspect of the present invention provides a tool adapted to assist the removal of the outer sheath from the cable, which tool has a body defining an aperture in which the cable may be received, a cutting blade projecting into the aperture and arranged to effect a lengthwise cut into the outer sheath as the tool is slid along the cable located in the aperture, and a generally convexly curved guide surface extending away from the aperture and over which the cut cable may be pulled as the tool is slid along the cable.

With the provision of the generally convexly curved guide surface as described above, the cable may be pulled so as to lie against the surface following the cutting thereof by sliding the tool along the cable towards the free end, and this has the effect of flexing the cable, so tending to split the outer sheath away from the conductors of the cable. This effect may be enhanced by having the guide surface on the side of the aperture remote from the side of the aperture from which the cutting blade projects - that is to say, following the cutting of the cable, the cut therein faces away from the convexly curved guide surface.

The generally convexly curved guide surface may have a substantially constant radius of curvature, or may have a radius of curvature which gradually decreases away from the aperture, so as to increase the degree of flexing of a cable constrained to follow that guide surface.

In one preferred embodiment of tool of this invention, there is provided an elongate body having an upstanding boss at one end. Said cable-receiving aperture extends transversely through the body and boss, there being a slot from one edge of the tool and leading to that aperture, so permitting the location of a cable within the aperture. The aperture is further defined by a passageway extending across the boss and aligned with said slot, whereby a cable may lie either transversely of the body or substantially parallel thereto. By rounding the faces of the passageway through the boss, the curved guide surface referred to above may directly be provided by the curved faces of the boss. The opposite end of the body conveniently has a finger-hole, to permit easy rotation of the tool about the cable when an annular cut is being performed.

This invention extends to a method of removing the outer sheath from a cable using a tool having an aperture defining two cable-receiving axes and a cutting blade projecting into the aperture, in which method a cable is located in the aperture to lie along one of the said axes, an annular cut is made around the cable by rotating the tool thereabout, the tool is moved relative to the cable so that the cable lies along the other principal axis, and then the tool is pulled towards the free end of the cable, the cutting blade then effecting a lengthwise cut along the length of the cable from the annular cut to the free end, which cut is to a greater depth than the depth of the annular cut. Preferably, the cable is flexed immediately after being cut lengthwise, in such a way as to expand the elongate cut into the cable, further to assist the removal thereof.

The invention further extends to a method of removing the outer sheath from a cable using a tool having a cable-receiving aperture and a pair of cutting blades adapted to project into the aperture from opposed sides thereof, in which method a portion of the cable spaced from the free end is located in the aperture and the cutting blades are caused to effect a pair of first cuts into the outer sheath, which first cuts extend in the circumferential direction of the sheath and penetrate the sheath to a first depth, and then the tool is drawn towards the free end of the cable during which action the cutting blades effect longitudinallyextending second cuts which second cuts penetrate the sheath to a greater depth than the first cuts.

By way of example only, one specific embodiment of a tool of this invention will now be described in further detail, reference being made to the accompanying drawings, in which: Figure 1 is a plan view of the tool; Figure 2 is a sectional view taken on line A-A marked on Figure 1; Figure 3 is an end view on the tool of Figure 1; and Figures 4 and 5 are diagrammatic scrap views diagrammatically illustrating the cutting action of the tool.

The illustrated embodiment of tool comprises a main body 10 having a slot 11 at one end dividing that main body into two arms 12 and 13, and at the other end a finger-opening 24. Each of the two arms 12 and 13 has formed thereon an upstanding boss 14 and 15 respectively. A cable-receiving aperture is defined between the combined arm 12 and boss 14 and the combined arm 13 and boss 15, which aperture has two principal axes, one transverse of the body 10, and the other parallel to the length of the slot 11. The part of the aperture having its axis transverse to the body 10 is defined by a re-entrant part-circular opening through both the body 10 and bosses 14 and 15, and into which the slot 11 communicates, the narrowest part of the slot 11 being of a smaller dimension than the diameter of the opening 16.The part of the aperture having its principal axis parallel to the length of the slot 11 is defined between the bosses 14 and 15, by faces 17 and 18 of the bosses 14 and 15, respectively. Both of those faces 17 and 18 are arcuately curved, as shown, but face 17 has a part-circular recess 19 generally centrally thereof, adjacent opening 16.

Embedded in the boss 12 is a cutting blade 20, the pointed cutting tip 21 of- which projects through the recess 19 into that part of the opening 16 lying between the bosses 14 and 15. A slit 22 extends from the opening 16 within the body 10 towards the finger-hole 24, which slit 22 has an enlarged hole 23 remote from the opening 16, this slit 22 serving to permit the arms 12 and 13 to spring somewhat relative to each other.

The tool described above has to be configured for use with a specific table type: that is, the size of the opening 16 as well as the spacing of the bosses must be appropriate for the diameter of the cable to be stripped. Moreover, the projection of the blade must be pre-set so as to be suitable for the dimensions of the outer sheath of the cable.

In order to use the tool, a cable which is to have its outer sheath removed is pressed through the slot 11 so as to lie in the opening 16 - that is, along axis B shown on Figure 3. The tool is then rotated about the cable, conveniently by inserting a finger in the hole 24 and turning the body 10 about the cable, during which action the tip 21 of the cutting blade 20 makes an annular cut into the cable to a first depth dl, as illustrated in Figure 4.

Next, the tool is turned about an axis mutually at right angles to the axis of opening 16 and length of the slot 11, until the cable lies along axis C shown on Figure 1. The tool should be turned in such a sense that the open end of the slot 11 is directed away from the free end of the cable. Again, using the finger-hole 24, the tool is then pulled towards the free end of the cable, during which action the tip 21 of the cutting blade 20 performs a lengthwise cut along the cable, from the annular cut to the free end. During this action, the cutting blade cuts into the cable to a depth d2, as illustrated in Figure 5, which depth is greater than the depth dl shown in Figure 4. This is on account of the fact that when the cable is located along axis C (i.e.

parallel to the length of the slot 11), the cable will lie in the recess 19, so allowing the blade 20 greater penetration into the outer sheath of the cable.

For many cables, the removal of the outer sheath will be assisted if the cable is flexed after cutting.

This may be achieved during the cutting action if the cable is pulled to lie against the convexly curved surface 18 of the boss 15, as the tool is moved towards the free end of the cable. This action will tend to split wider open the cut made into the cable, so facilitating subsequent removal of the outer sheath.

The tool described above may be modified by the addition of a second blade, projecting into the aperture from a position opposed to that from which blade 20 projects. Face 18 of boss 15 should then be formed in a similar manner to face 17 of boss 14, in order that the second blade may perform in a similar manner to blade 20.

Though this modified form of tool may be used as described above, it would instead be possible to omit the step of rotating the tool about the cable after inserting the cable transversely into the aperture. The act of inserting the cable will cause the two blades each to effect a cut to said first depth and having a circumferential extent, whereafter the tool may 'be turned to have the cable lying over face 17 (or 18), to permit pulling of the tool towards and off the free end of the cable. During this action, the two blades each will effect lengthwise cuts, in each case to said second depth.

The blades used in this modified form of tool may have shapes differing from that shown in Figure 1: for example each blade may be generally arcuate whereby the circumferential extent of the cut effected thereby is increased without the need to rotate the tool about the cable.

Claims

1. A tool adapted to assist the removal of an outer sheath from a cable, which tool has a body provided with an aperture to receive the cable and a cutting blade mounted to project into the aperture, the tool being configured such that when a cable is located in the aperture and the tool is rotated thereabouc, the cutting blade penetrates the outer sheath to a first depth, and when the tool is slid along the wire, the cutting blade then penetrates the outer sheath to a second depth, greater than said first depth of penetration.

2. A tool according to Claim 1, and adapted for use with a predetermined cable having an outer sheath of a known thickness, wherein the depth of penet:.-ation of the cutting blade is pre-set to be not greater than the minimum wall thickness of the outer sheath of that cable for the case where the tool is rotated about the cable, but the depth of penetration ot the cutting blade is pre-set substantially to sever the outer sheath when the tool is slid along the cable.

3. A tool according to claim 1 or Claim 2, wherein the tool has a main body which supports the cutting blade in a relatively movable manner, and the blade is shifted with respect to the main body depending upon the sense of movement of the tool with respect to the cable.

4. A tool according to Claim 3, wherein means are provided automatically to shift with respect to the main body, by virtue of friction between the blade and the cable.

5. A tool according to claim 3, wherein a manuallyoperable control is provided for the blade, to alter the projection of the blade into the aperture.

6. A tool adapted to assist the removal of an outer sheath from a cable, which tool has a body provided with a cable-receiving aperture having two principal axes disposed at an angle to one another, the aperture being configured to permit a cable to lie therewithin along either principal axis, and a cutting blade mounted on the body to project into the aperture to penetrate the outer sheath of a cable located therein and lying along either axis, the tool being rotatable about a cable located in the aperture and lying along one principal axis thereof, whereby the blade performs an annular cut into the outer sheath of the cable, and the tool being slidable along a cable when located in the aperture along the other principal axis thereof, whereby the cutting blade then performs a lengthwise cut along the cable.

7. A tool according to Claim 6, wherein the configuration of the aperture is such that when a cable is located therein, the tool may be turned with respect to the cable about an axis substantially intersecting the cable axis, whereby the tool may be turned to have the cable lying selectively along either principal axis of the aperture.

8. A tool according to Claim 6 or Claim 7, wherein the walls defining the aperture have concave portions about both of said principal axes, whereby anappropriately-dimensiona' cable located within tine aperture and lying along either one of said principal axes is restrained in the aperture along that axis.

9. A tool according to any of Claims 6 to 8, wherein the aperture is configured such that when a cable l=.es along said one principal axis of the aperture the cutting blade penetrates the outer sheath of the cable to a first depth, but when the cable lies along said other axis of the aperture, the cutting blade then penetrates the outer sheath to a second depth greater than said first depth.

10. A tool according to Claim 9, wherein the two principal axes of the aperture are arranged at an angle to one another in a non-intersecting manner, one said principal axis beirig further from the cutting edge of the cutting blade than the other principal axis.

11. A tool adapted to assist the removal of an outer sheath from a cable, which tool has a body provided with a cable-receiving aperture and a pair of cutting blades arranged to project into the aperture from opposed sides thereof, the tool being provided with means to control the projection of the blades with respect to the sides of the aperture and said means being configured to cause the blades to penetrate a cable located in the aperture to a first depth when the blades are to cut in the circumferential direction of the sheath, and to penetrate the cable to a second depth greater than said first depth when the blades are to cut in the longitudinal direction of the sheath.

12. A tool according to Claim 11, wherein said controlling means comprises appropriately-configured lands or other surfaces forming a part of the body and defining said cable-receiving aperture and from which the cutting blade projects.

13. A tool according to Claim 11 or Claim 12, wherein each blade is mounted on a respective carrier which is mounted on the body for relative movement with respect thereto, whereby the depth of penetration of the carried blade may be controlled by moving the carrier with respect to the body.

14. A tool according to Claim 13, wherein each blade projects from a surface of its carrier having a pair of intersectinj grooves either one of which may contact the cable, the blade being positioned in the intersecting region of the grooves and said controlling means being arranged to turn the carrier with respect to the body selectively to hav e the cable extending along either groove.

15. A tool adapted to assist the removal of the outer sheath from a cable, which tool has a body defining an aperture in which the cable may be received, a cutting blade projecting into the aperture and arranged to effect a lengthwise cut into the outer sheath as the tool is slid along a cable located in the aperture, and a generally convexly-curved guide surface extending away from the aperture and over which the cut cable may be pulled as the tool is slid along the cable.

16. A tool according to Claim 15, wherein said guide surface is provided on the side of the aperture remote from the side thereof from which the cutting blade projects, whereby a longitudinal cut formed by the tool will face away from the convexly-curved guide surface.

17. A tool according to Claim 15 or 16, wherein the convexly-curved guide surface has a radius of curvature which gradually decreases away from the aperture, so as to increase the degree of flexing of a cable constrained to follow that guide surface.

18. A tool according to any of Claims 15 to 17, wherein the tool has an elongate body provided with an upstanding boss at one end thereof, scid cablereceiving aperture extending transversely through the body and boss, and there being a slot from one edge of the tool and leading to that aperture, so permitting the location of a cable within the aperture, which aperture is further defined by a passageway extending across the boss and aligned with said slot, whereby a cable may lie either transversely of the body or substantially parallel thereto, and the faces of the passageway through the boss being curved to define the convexly-curved guide surface.

19. A method of removing the outer sheath form a cable using a tool having an aperture defining two cablereceiving axes and a cutting blade projecting into the aperture, in which method a cable is located in the aperture to lie along one of the said axes, an annular cut is made around the cable by rotating the tool thereabout, the tool is moved relative to the cable so that the cable lies along the other principal axis, and then the tool is pulled towards the free end of the cable, the cutting blade then effecting a lengthwise cut along the length of the cable from the annular cut to the free end, which lengthwise cut is to a greater depth than the depth of the annular cut.

20. A method according to Claim 19, wherein the cable is flexed immediately after being cut lengthwise to expand the elongate cut into the cable.

21. A method of removing the outer sheath from a cable using a tool having a cable-receiving aperture and a pair of cutting blades adapted to project into the aperture from opposed sides thereof, in which method a portion of the cable spaced from the free end is located irl the aperture and the cutting blades are caused to effect a pair of first cuts into the outer sheath, which first cuts extend in the circumferential direction of the sheath and penetrate the sheath to a first depth, and then the tool is drawn towards the free end of the cable during which action the cutting blades effect longitudinally-extending second cuts which second cuts penetrate the sheath co a greater depth than said first cuts.

22. A tool adapted to assist the removal of an outer sheath from a cable and substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.

23. A method of removing the outer sheath from a cable, substantially as hereinbefore described wit reference to the accompanying drawings.