GB2238670A

GB2238670A - Cable stripping tool

Info

Publication number: GB2238670A
Application number: GB9024900A
Authority: GB
Inventors: John Henry Carr; Paul Alexander Long; David Leslie Ogden
Original assignee: British Telecommunications PLC
Current assignee: British Telecommunications PLC
Priority date: 1989-11-15
Filing date: 1990-11-15
Publication date: 1991-06-05
Anticipated expiration: 2010-11-15
Also published as: GB2238670B; GB9024900D0

Abstract

A hand tool for splitting the sheath of a cable includes a handle formed from a body 11/12, with twin blades 19/25, therein. The blades slit the cable sheath on opposite sides as the tool is moved relative to the cable so as to expose the conductors and the rip cord. This cord can be held in the tool to assist with further slitting e.g. at notches 28. The ribs 16, 17 prevent sideways movement of the handles when cutting. Adjacent the blades the channel 15 is wider to allow room to split the sheath. The body is provided with stepped portions 11a, 12a to assist gripping. In another embodiment (Figs 8 to 11) indentations (41) in the body assist gripping and the blades (46, 47) are held by screws (52, 52). Replacement blades may be held in the tool. <IMAGE>

Description

HAND TOOL The invention relates to a hand tool associated with stripping cables and more particularly to splitting the cable sheath to allow access to the inner cable conductors.

To gain access to cables contained within a sheath, this outer sheath is typically slit longitudinally with a knife and a rip cord inside the sheath is then grasped manually and pulled to split the sheath to the desired length. It requires skill to provide the correct depth of cut consistently.

An improvement in this technique has been the provision of cable stripping tools specifically designed to slit the outer sheath or such cables. This may typically comprise a handle portion with a single blade extending from the tool end remote from the handle. A spring loaded, hooked portion is provided to overlie the cable so as to bring the blade into contact with the sheath.

Such arrangements still require considerable skill because the blade requires adjustment to get the exact depth of cut required. Too little depth will result only in scoring the sheath and too much can damage the blade.

Further the resilient hooked portion tends to make it awkward to pull the tool longitudinally in an accurate manner at the same time applying sufficient pressure to the spring loaded mechanism. Often, one cut may not readily expose the rip cord and a further longitudinally cut may be required away from the original cut. Further the initial cut may be somewhat jagged and not in line with the axis of the cable making pulling of the rip cord difficult.

The present invention is concerned with providing a simple and reliably operable tool.

According to the invention there is provided a cable tool for splitting the sheath of a cable, comprising a handle portion, means defining an aperture through said handle to allow the cable to pass therethrough, and a pair of blades within the aperture for penetrating the cable sheath to allow slitting thereof.

Preferably, means are provided for moving one or both of the blades away from the cutting position.

Such means may comprise a pivot, hinge or the like.

Weans may be provided for effecting automatic movement of the blades away from the bore on insertion of the cable.

Means may be provided to grip the rip cord following slitting of the sheath to allow further opening thereof.

Preferably, the blades are replaceable.

Further, according to the invention there is provided a method of splitting a cable sheath comprising positioning a cable in an aperture within a handle portion of a cable tool and moving the tool longitudinally of the cable whilst two blades of the tool are applied to the sheath to effect slitting thereof at two locations.

Preferably, the method includes moving at least one of the blades towards or away from the cutting position.

The method preferably includes gripping the exposed rip cord with the tool to allow further opening of the sheath to be effected The method may include inserting the cable to automatically cause the blades to move apart to allow passage of the cable therethrough.

The invention will now be described by way of example with reference to the embodiments described in the accompanying drawings in which: Figure 1 shows an embodiment of the cable tool of the invention with the handle portion pivoted into the open position; Figure 2 shows an end view of the tool of Figure 1 in the closed position to illustrate the pair of opposing blades in the channel through which the cable will be pulled relative to the tool; Figure 3 shows a detail of one of the replaceable blades located in the channel; Figures 4 to 7 show the various stages in the slitting process; Figure 8 shows a second embodiment of the cable tool of the invention; Figure 9 shows the tool viewed from end 13 (and 0 rotated through go relative to Figure 8; Figure 10 shows a sectional view of the tool through A-A of Figure 9; and Figure 11 shows an end view with the slots for receiving the rip cord.

The tool 10 Figure 1 for splitting the sheath of a cable is an easily portable and pocketable tool (eg. when folded into the closed position) and can typically measure only 100mm in length and 25mm width and height.

The tool comprises a two part housing 11, 12 hinged about pivot 13. Other suitable forms of hinging could be provided (eg. a hinge formed by the moulding itself). The housing can be moulded of suitable plastics material (eg.

polypropylene).

The majority of the housing forms the handle portion of the tool in use and tapers towards the hinged area to aid manual grip. To further aid gripping, the outer faces may be ribbed. A step lla, 12a is provided adjacent the hinge region to further assist the grip.

The lower housing portion 11, includes an open-ended V-shaped groove 15 and upstanding wall portions 16, 17 on either side thereof, and extending longitudinally to form a channel into which the cable will be located. A blade 19 is located centrally in the channel so as to penetrate the cable sheath in use. The blade is disposed towards the hinged end of the body to give added mechanical advantage when carrying out slitting using manual pressure.

As can be seen from Figure 3, in the region adjacent to the blade, the wall portion 16a, 17a is of reduced width so that a channel area of greater width is created to allow for expansion of the cable sheath when the blade penetrates it during slitting to aid the slitting action.

This reduces the force required to pull the cable through due to resistance and other factors whilst retaining the degree of guidance elsewhere to ensure the cable is not pushed to one side of the channel. The blade 19 is shown in a fixed position in holder 20 (within recess 15a) and no adjustment is required in use. The blade can be replaced after (say) 1000 operations by removing the blade 19 and holder 20 from the recess. A small aperture (not shown) through the lower face 14 of the housing portion 11 can assist in removal of the blade by pushing the holder with a suitable implement.

The upper portion 12 of the housing also includes an open-ended V-shaped groove 21 which is similarly dimensioned to groove 15 of the lower portion 11. The wall portions 22, 23 are perpendicular to the major face 24 of the upper housing portion 12 and form a channel which, as seen in Figure 2, accommodates the upstanding wall portions 16, 17 so that in the closed position the tool provides a duct with an aperture through which the cable can pass. Because the wall portions 16, 17 of body portion 11 are located within the other body portion 12 (in the closed position), this prevents relative sideway movements of the two handle portions to ensure accurate guidance is maintained. The upstanding wall portions 16, 17 also act as a guard for the blade 19 to prevent accidental injury to the user when in the open position.

A rear aperture 26 in the body portion 12 allows the cable to be fed into the tool when the tool in in an open position.

A blade 25 and an associated holder (corresponding to blade 19 and blade holder 20) is centrally located in the groove 21 and extends into the duct aperture at a position opposite the blade 19 so that both blades can operate on the cable sheath in the same region, but diametrically opposed. Walls 22, 23 also act as a blade guard for blade 25. The blades cut the sheath along the centre axis to make further splitting using a rip cord of the cable much more effective.

To assist in use of this rip cord a small channel 28 is provided ir. the walls 16 and 17 and perpendicular thereto. This will locate the rip cord prior to closing the upper body portion 12, which will firmly grip the cord therein on applying manual pressure and on pulling of the rip cord will cause further splitting.

The hinged body portions 11 and 12 during the slitting operation act as two lever arms and this action is now described in detail with reference to Figures 4 to 7.

The tool is used by moving the body portion 12 upwards into the position shown in Figure 4. The cable is then fed into the channel via the aperture 26 till a length typically 175mm extending beyond the aperture is deployed (see Figure 5). The two portions 11, 12 are then brought together, see Figure 6, and manual pressure applied. This will cause the two blades to pierce and penetrate the cable sheath at opposite sides.

Thereafter, as in Figure 7, by continuing to apply hand pressure and with the thumb uppermost, (contacting ridge 12a) and the first finger contacting ridge ila and by holding the cable with the other hand, the tool is pulled longitudinally of the cable to slit the cable sheath at two locations.

Thereafter the rip cord can be readily accessed and placed in the grooved location of the tool and pulling the handle will cause the rip cord to split further one side of the sheath to the desired length. The split sheath can then be cut off.

As mentioned above, blades can be replaced when work and a storage compartment may be provided with a sliding cover (not shown) in the handle to retain the spare and used blades.

In a second embodiment shown in Figure 8, the handle is more tubular in shape and is constructed as a single body 40.

The elongate body 40 is moulded from suitable plastics material (eg Nylatron). The body is of a generally cylindrical shape but indentations 41 are provided at intervals to allow a user's fingers to grip the tool more securely.

The body although moulded as a single component, between an aperture 12 and one end 43, this is split into two parts 40a, b along a portion of its length (see Figures 9 and 10). Wall portions 44 adjacent the aperture 42 are thinner than along the main part of the body (because of aperture 42) and this aids the resilient hinging or flexing of the tool body portions 40a, 40b relative to each other and to the fixed body portion 49 to allow diametrically opposite twin blades 46, 47 located in central circular bore 48 (see Figures 9 and 10) to automatically be moved apart a sufficient distance on passing a cable through the bore to allow the cable to pass through without undue hindrance. The cable can be inserted from end 43 or the other end 45 and dependent on whether the user draws the tool towards, away from or across his/her body.As shown in Figure 10, the bore adjacent ends 43, 45 is conical to assist in cable entry from that respective direction.

When sufficient cable has passed through the bore (eg 150mm), the body portions 40a, b are gripped and on pulling the tool the blades 46, 47 cut into the sheath and slit the sheath at two diametrically opposite points as it moves through the tool.

Manual pressure will tend to oppose the resilience of the tool and the step 54 will aid the gripping of the tool by the thumb and first finger is the region of aperture 42.

Slitting of the cable sheath longitudinally exposes the conductors and the rip cord. To cause additional slitting of the sheath the rip cord now exposed can be gripped in slots 50, 51 (see Figure 11) and pulled using the tool.

As shown in Figure 10, the blades 46 and 47 are carried on replaceable screws 52, 53. These blades can thus be replaced by unscrewing.

Also as seen from Figure 10, the bore 48 in the region of the blades in constricted to ensure the cable is guided against the blades without twisting to ensure correct splitting of the sheath.

By enclosing the blades in the manner described, the operator is not at risk from cuts received by careless use or as a result of accidents.

Claims

CLAINS

1. A cable tool for splitting the sheath of a cable, comprising: a handle portion, means defining an aperture through said handle to allow the cable to pass therethrough, and a pair of blades within the aperture for penetrating the cable sheath to allow slitting thereof.

2. A tool as claimed in claim 1 including means for moving one or more of the blades away from the cutting position.

3. A tool as claimed in claim 2 wherein the means is configured to move one part of the handle relative to another.

4. A tool as claimed in claim 3 wherein the handle izldes a pivot, hInge =r thc like to effect said movement and wherein each of the two blades are affixed to opposite parts of the handle to cause the blades to move apart when the handle parts move apart.

5. A tool as claimed in any one of claims 1 to 4 wherein the blades are replaceable.

6. A tool as claimed in any one of claims 1 to 5, where in means are provided to grip the rip cord following slitting of the sheath to allow further opening thereof.

7. A tool as claimed in any one of claims 1 to 6, wherein the means for defining an aperture comprises a duct extending through the handle of the tool.

8. A tool as claimed in claim 7, wherein the duct comprises a pair of channels extending longitudinally, one in each of two opposing parts of the handle and wherein one of the two blades is located within the respective channels.

9. a tool as claimed in any one of claims 1 to 8 wherein step means are provided on the handle to assist in gripping the tool.

10. A tool as claimed in claim 8 wherein the channels each include a generally V-shaped portion.

11. A tool as claimed in claim 5 wherein the blades include a holder for replacement with the blades.

12. A tool as claimed in claim 5 or 11 wherein a storage compartment is provided within the handle to receive replacement blades.

13. A tool as claimed in claim 7 or 8 wherein means are provided for allowing the passage of an expanding cable sheath in the region of the blades.

14. A tool as claimed in claim 7, 8, 10 or 13 wherein a portion of the duct in the region of the blades is enlarged to assist in allowing the passage of the expanded cable sheath in the cutting region.

15. A tool as claimed in claim 7, 8, 10 or 13 wherein the blades are resiliently mounted to allow the passage of the expanding cable sheath in the region of the blades.

16. A tool as claimed in claim 7, 8, 10, 13, 14 or 15 wherein the duct extends throughout the handle portion.

17. A tool as claimed in claim 7, 8, 10, 13 or 14 wherein the channels are delimited by wall portions in each of the two opposing parts of the handle, the wall portions in one part of the handle being configured to locate with the wall portions of the other part or the handle.

18. A tool as claimed in any one of claims 1 to 6 wherein the means defining an aperture includes a bore extending through the handle and means are provided for automatically effective movement of the blades away from the bore on insertion of the cable.

19. a tool as claimed in claim 18 wherein the blades are resiliently mounted to allow movement thereof.

20. A tool as claimed in claim 18 or 19 wherein the bore in the region of the blades is constricted to assist in cable guidance.

21. A tool as claimed in claim 18, 19 or 20 wherein the bore is located in a duct and at least a portion of which duct is non-moveable.

22. A tool as claimed in any preceding claim wherein the outer face of the handle is ribbed to assist gripping thereof.

23. A tool as claimed in claim 22 where the handle is substantially tubular.

24. A method of splitting a cable sheath, comprising: positioning a cable in an aperture within a handle portion of a cable tool and moving the tool longitudinally of the cable whilst two blades of the tool are applied to the sheath to effect slitting thereof at two locations.

25. A method as claimed in claim 24 including, moving at least one of the blades towards or away from the cutting position.

26. A method as claimed in claim 25 including moving one part of the tool relative to another.

27. A method as claimed in claim 26 including pivoting part of the tool handle to move one blade from the cutting position.

28. A method as claimed in any one of claims 24 to 27, including gr ppir,g the exposed rip cord with the tool to allow further opening of the sheath to be effected.

29. A method as claimed in any one of claims 24 to 28, including the step of replacing the blades whenever they become worn.

30. A method as claimed in any one of claims 24, 25 or 26 including inserting the cable in the aperture to automatically cause the blades to move apart to allow passage of the cable therethrough.

31. A method as claimed in claim 30 including gripping the tool to move the blades towards the cable.

32. a cable tool for splitting the sheath of a cable substantially as described herein the reference to any one of the embodiments shown in the accompanying drawings.

33. A method of splitting a cable sheath substantially as described herein.