Cable Sheath Cutting Apparatus

Abstract

A tool for removing the sheath from cables. A cutting edge is positioned between two serrated drive rollers which engage with the cable periphery. Opposed to the drive rollers are support rollers. The drive rollers are rotated to move the tool on the cable. The drive rollers and cutting edge can be arranged to cut axially of the cable or circumferentially.

Description

This invention relates to apparatus for cutting the sheath of a cable; in particular for cutting circumferentially and longitudinally so that portions of a cable sheath can be removed.

The present techniques for removal of cable sheathing are rather haphazard in that control of depth of cut is either not obtained or difficult to attain for example because of out of roundness or other dimensional variation of the cable; damage to a conductor, or conductors, is possible; considerable care is necessary; and sheath removal in very cold weather usually requires preheating of the cable to make the sheath more flexible -particularly for plastic sheathing.

Hitherto sheathing has been removed in various ways, for example by using a hacking knife to remove a slice of sheathing for plastic sheathing, or to cut one or more slits in other sheathing such as lead or aluminum. Circumferential cuts may be made by a hacking knife or by a saw. It will be appreciated that use of a knife or a saw does not provide accurate control over the depth of cut. The problem is accentuated with cables having a bonded sheath in that it is difficult to tell when the sheath is cut through, without damaging the conductors. Heating or warming of the cable before removal of the sheath is also inconvenient and time consuming.

The present invention provides a means for cutting the sheath of a cable, giving a cut of controlled depth, independent of any mis-shaping of the cable cross-section, quickly and easily. Cuts can be made circumferentially, and longitudinally, as required. The cuts are made by a cutter in association with a driving wheel which engages the cable sheath. The cable is urged into engagement with the driving wheel which is rotated to move the cable relative to the cutter. The blade is preset for depth of cut and thus a constant depth of cut is obtained.

In accordance with the present invention, apparatus for cutting the sheath of a cable, comprises: a driving wheel for engagement with the cable sheath; at least one pressure roller in opposition to the driving wheel; means for urging the pressure roller towards the driving wheel, whereby the cable will be gripped therebetween; a cutter associated with one of said driving wheel and said roller and adapted for setting for a predetermined depth of cut; and means for rotating the driving wheel to move the cable relative to the cutter to cut the sheath.

Conveniently the cutter is associated with the driving wheel and the driving wheel and the cutter may be mounted for rotation about an axis normal to the axis of the cable whereby circumferential and longitudinal cuts can be made suitable directing of the driving wheel and the cutter.

The invention will be understood by the following description of an embodiment in conjunction with the accompanying drawings in which:

FIG. 1 is an end view of the apparatus, adapted to make circumferential cuts;

FIG. 2 is a cross-section through the apparatus of FIG. 1 on the center line;

FIG. 3 is a cross-section on the line III--III of FIG. 1;

FIG. 4 is an end view of the apparatus, adapted to make longitudinal cuts; and

FIG. 5 is a cross-section through the cutting wheel and mounting in the position illustrated in FIG. 3.

The apparatus, or tool, has a frame member 10 to one end of which is attached, as by welding, a sleeve 11. A housing 12 is supported in the sleeve 11 by a spigot 13 extending from the housing. The spigot 13 is threaded at its end, at 14, and a knob 15 is screwed onto the threaded end. An abutment shoulder 16 is formed in the sleeve 11 at its end adjacent the housing 12 and a compression spring 17 is positioned between the abutment shoulder 16 and the end of the knob 15. When the knob is completely screwed onto the end of the spigot 13 there is a small clearance 18 between an abutment surface 19 on the knob and the adjacent end surface 20 of the sleeve 11. This permits slight axial movement of the housing 11 for a purpose to be described.

As will be seen in FIGS. 2 and 4 the housing 12 is cylindrical in cross-section one end being permanently closed by an end plate 23 and the other end closed by a removable plate 24 secured by screws 25. An axle 26 is mounted in the end plate 23 and removable plate 24 by means of roller bearings 27 and carries two spaced apart driving wheels 28 fixedly attached thereto. The wheels are serrated on their peripheries, as seen at 29 in FIG. 1.

Mounted between the driving wheels 28 is a cutter 30. The spigot 13 supporting the housing 12 is hollow and the cutter 30 has an extension 31 which passes up through the spigot 13. The end of the extension 31 is threaded and a hollow internally threaded adjustment member 32 is screwed onto the end of the extension 31. The inner end of the adjustment member 32 has a flange 33 formed thereon, the flange engaging with an abutment 34 on the knob 15. The adjustment member is thus retained in position by the flange 33 being held between the abutment 34 and the end of the spigot 13. Rotation of the adjustment member 32 moves the extension 31 axially and thus moves the cutter 30 relative to the housing 12 and the driving wheels 28. By this means the amount by which the cutting edge 35 of the cutter 30 extends beyond the periphery of the driving wheels can be controllably adjusted, and this in turn controls the depth of cut made in the sheath. Conveniently the cutting edge 35 is formed as a readily removable and replacable part of the cutter 30.

The axle 26 has one end enlarged at 40, the enlarged end being formed with a square cross-section hole 41 in which is fixed a square driving member 42. Member 42 is retained in the hole 41 by a screw 43. Driving member 42 is adapted to receive a ratchet handle 44, as in FIGS. 1 and 4, by which the driving wheels 28 can be rotated, in either direction as required. Alternatively the hole 41 can accept the drive spigot of a ratchet handle having such a spigot.

Mounted on the other end of the frame 10 is a bracket 50. The bracket is adjustable along the frame, being held in a desired position by a lever 51, spring loaded by a compression spring 52, engaging with a series of transverse grooves 53 on the frame. The bracket 50 can easily be pushed up towards the sleeve 11, the lever riding over the teeth between the grooves 53, but engagement by the lever 51 with the grooves 53 prevents undesired movement of the bracket away from the sleeve 11. Inadvertent complete removal of the bracket from the frame 11 is prevented by a pin 54.

Bracket 50 has a bore 60 axially in line with the axis of the sleeve 11. Slidable in the bore 60 is a sleeve 61 having one end closed by a flange 63, the closed end being toward the sleeve 11. Attached to the flange 63 is a holder 64. Holder 64 also is supported on the frame 11 so as to be slidable thereon. Carried on the holder 64 are four rollers 65. The rollers 65 are mounted with their axes inclined to form a Vee, and one in two parallel pairs, as seen in FIG. 3. Depending from the main body portion of the bracket 50 are two parallel spaced apart webs 66. Slidably supported between the webs 66 is an actuating pin 67. Pin 67 has an enlarged head 68 having opposed flat surfaces for sliding engagement with the inner surfaces of the webs 66. The end of the pin 67 remote from the head 68 is seated in a hole in the flange 63 of the sleeve 61. The sleeve 61 is retained on the pin 67 by a screw 69. Surrounding the pin 67 is a compression spring 70, the spring extending between the flange 63 of the sleeve 61 and the head 68 of the pin 67. A further compression pring 71 is positioned in a hole 72 in the bracket 50 and also acts against the head 68 of the pin 67. At the lower ends of the two parallel webs 66 is a transverse pin 73. Pivotally mounted on the pin 73 is a lever cam 74 the cam surface acting on the head 68 of the pin 67. Actuation of the lever cam 74 lifts the pin 67, against the action of spring 71. Spring 70 pushes the sleeve 61 upwards together with the holder 64 and the rollers 65. This position is seen in FIG. 3, while FIG. 2 illustrates the position when the lever cam is in the inoperative position.

As illustrated in FIGS. 1 and 2 the apparatus is set to cut a cable sheath peripherally, and in FIGS. 4 and 5 it is set to cut longitudinally. The cutter is set to cut one way or the other by a suitable rotative position of the housing 12 in the sleeve 11. The sleeve 11 is provided with two recesses 80 and 81 in the lower end surface 83 against which the housing abuts under the action of the spring 17. In the housing there is fixed a pin 84, the head of the pin positioned so as to enter one or the other of the recesses 80 or 81, depending upon the rotative position of the housing. To rotate the housing 12, together with the drive wheels 28 and cutter 30, the knob 15 is first pushed down against the action of the spring 17. This moves down the housing 12 and the head of the pin 84 leaves the recesses 80 or 81, and then the knob 15 is turned through 90.degree.. Release of the knob enables the spring 17 to push the knob 15 and housing 12 upward, the head of the pin 84 enters the other of the recesses 80 or 81.

The apparatus or tool, is operated as follows. The bracket 50 is lowered, by pressing on lever 51 to release it from the grooves 53, to admit the cable to be cut. The housing 12 is rotated in the sleeve 11 so as to set the cutter for cutting peripherally, that is in the position, or setting, as in FIGS. 1 and 2. The amount by which the cutting edge 35 extends beyond the peripheries of the driving wheels 28 is adjusted by the adjustment member 32 so as to cut the desired depth --generally the thickness of the sheath.

Bracket 50 is then pushed upward until the rollers 65 engage the cable with the drive wheels 28, the lever cam 74 in the inoperative position, as in FIG. 1. The bracket is retained in this position by engagement of the lever 51 with the grooves 53. The lever cam 74 is then actuated, forcing the cutting edge 35 into the cable. Rotation of the drive wheels 28 by the ratchet handle 44 rotates the apparatus, or tool, around the cable, the serrations on the drive wheels ensuring a positive rotational drive relative to the cable. As the tool moves round the cable the cutting edge 35 cuts the sheath peripherally.

If a portion of a cable sheath is to be removed at an intermediate position, which is often so, the tool is moved axially along the cable. This is readily done by first moving the lever cam 74 to its inoperative position (FIG. 1) then releasing the bracket 50 by disengaging lever 51. At the new position the driving wheels 28 and cutter 30 are re-engaged as previously and a further circumferential cut made. The tool is then released again and the cutting and driving wheels rotated through 90.degree. by pressing on the knob 15 and rotating. The longitudinal cuts are made in a similar manner to the circumferential cuts. The driving wheels 28 and the cutter 30 are re-engaged with the cable by first pushing up the bracket 50 and then moving the lever cam to the operative position (FIG. 4). The ratchet handle is actuated to rotate the drive wheels and the cutting edge 35 makes a cut along the cable. The cut is started at one circumferential cut and finished at the other. The tool is disengaged, the tool moved 180.degree. around the tool, the tool re-engaged and a further cut made diametrically opposite the first. The two halves of the sheath are then pried off, for example by a screwdriver.

The apparatus can be used for removing sheathing at the end of a cable, in which case only one circumferential cut need be made. The apparatus will follow a curve, if the cable is bent. Any out-of-roundness of the cable is accepted by the ability of the rollers to move, against the action of the spring 70. Sheathing can be cut for all types of cable: -- P.V.C. sheathed; bonded plastics; polyethylene; aluminum and lead. Cable sheathing can be cut regardless of weather conditions, even in very cold weather, no warming of the cable is needed. A major difficulty has been in the removal of sheathing of cables in which the plastic sheathing is bonded to an aluminum shielding layer. The apparatus of the present invention will cut this form of sheathing effectively so that easy and complete removal is obtained. The plastic sheath, layer of aluminum tape and the core wrap can be removed in one step.

Modifications can readily be made to the apparatus without departing from the concept of the invention. Thus, for example if considered useful, it can be arranged that the cutter only cuts in one direction, that is circumferentially or longitudinally. In such an arrangement the housing will be fixed. Only one driving wheel could be provided, with the cutter in close position alongside the wheel.

Instead of four rollers 65, two parallel rollers could be used, possibly each roller having a concave profile viewed normal to the rotational axis of the roller or even a single roller. Other ways of positioning the bracket 50 could be used, and of actuating the rollers into pressing engagement with the cable.

If cuts are to be made only in one direction then it is possible for the cutter to be associated with the rollers 65 but the arrangement described and illustrated provides a very satisfactory, efficient and easily used tool. With the tool it has been found that a length of sheathing can be removed readily in 5 minutes or less, even with cable which had been cooled to 0.degree.F.

In a further modification the driving wheels can be driven by power means. For example an electric motor could be used, with a flexible drive and suitable gearing. Other forms of hand operation than a ratchet handle can be used, for example a capstan.

Claims

What is claimed is:

1. Apparatus for cutting the sheath of a cable, comprising: a frame; a driving wheel mounted on the frame for engagement with the cable sheath; support means on the frame; a pressure roller mounted on the support means, and having limited movement in a direction normal to the rotational axis of the driving wheel; resilient means for urging the pressure roller in said direction in opposition to said driving wheel; additional means for moving the pressure roller towards the driving wheel, whereby the cable will be gripped therebetween; a cutter associated with one of said driving wheel and said pressure roller and adapted for setting for a predetermined depth of cut; and means for rotating the driving wheel to move the cable relative to the cutter to cut the sheath.

2. Apparatus as claimed in claim 1, the cutter associated with the driving wheel, the driving wheel and cutter supported in a housing on the frame for rotation about an axis normal to the axis of rotation of the driving wheel between a first and a second position, the cutter aligned in the first position for relative movement of the cable longitudinally and in the second position for relative movement of the cable about the cable axis.

3. Apparatus as claimed in claims 1 and 2, comprising two parallel spaced apart driving wheels, the cutter positioned between the wheels.

4. Apparatus as claimed in claims 1 and 2, comprising two pairs of pressure rollers, the rotational axes of the rollers of one pair inclined relative to the rotational axes of the rollers of the other pair to form a VEE formation.

5. Apparatus as claimed in claim 1 the support means for the pressure roller slidably mounted on said frame for movement towards and away from said driving wheel.

6. Apparatus as claimed in claim 1, including support means on said frame for supporting the roller, the support means including a bracket slidable on said frame towards and away from the driving wheel; a holder for said pressure roller mounted in said bracket for movement toward and away from the driving wheel; actuating means for moving the holder towards the driving wheel; and resilient means positioned between said actuating means and the holder urging the holder toward the driving wheel, whereby the roller is resiliently urged into contact with the cable.

7. Apparatus as claimed in claim 6, said actuating means comprising a cam.

8. Apparatus as claimed in claim 6, said bracket including a lever, and means urging said lever into engagement with formations on said frame, whereby the bracket can be positioned at desired locations on the frame.

9. Apparatus as claimed in claim 1 the means for rotating the driving wheel comprising a ratchet handle.

10. Apparatus as claimed in claim 2, including a sleeve attached to said frame, said housing mounted in said sleeve for rotation about said axis normal to the axis of rotation of the driving wheel, and for limited axial movement in said sleeve, resilient means urging the housing axially in said sleeve in a direction away from said pressure roller; means for moving said housing axially against said resilient means and for rotating said housing in said sleeve, and locating means for locating said housing at said first and second positions, said locating means disengaged by said moving of said housing axially against said resilient means.

11. Apparatus as claimed in claim 2 said cutter mounted for movement relative to said driving wheel along the axis of rotation of said housing, and means for moving the cutter along said axis to controllably adjust the position of the cutter relative to said driving wheel, whereby the depth of cut can be varied.