GB2225673A - Cable stripper - Google Patents

Abstract

A cable stripper comprises a casing on which there is disposed a blade carrier 2, and a blade (4, Fig. 1) mounted in the carrier, the blade and blade carrier being associated with means (8) for enabling the provision of a number of different blade positions in relation to a cutting aperture through the stripper adapted to receive a cable for stripping, the casing being provided on an outer surface thereof with a plurality of length markings 13. <IMAGE>

Description

CABLE STRIPPER This invention relates to a cable or wire stripper of the type which is adapted to remove various layers from a coaxial cable so as to expose the various layers in predetermined lengths for jointing or other purposes.

Many cables have multi-layer protection for the central conductor. For example, in a commonly employed coaxial cable an inner conductor is covered by an inner dielectric insulation layer and this is covered by one or two layers of outer conductors. Over the outer conductor there is usually an outer sheath and in order to strip the cable it is necessary to remove various layers so as to expose the central conductor, the dielectric, and the outer conductor at intervals along the length of the end portion of the cable.

This requires very accurate cutting and stripping so as to avoid damaging the central conductor, the dielectric and the outer conductor. It is desirable to leave the outer conductor, for example, in almost perfect condition as any damage to the outer conductor can cause interference to signals.

An object of the invention is to provide a simple manually usable tool of portable type which can be used in the field to strip cables very accurately and without damage to the cables.

In our UK Patent No 2173958B there is defined a cable stripper comprising a casing on which is pivoted a blade carrier, a blade mounted in the carrier, the carrier being spring biased against a cam stop, the cam stop having a number of cam faces which may be presented in turn to the carrier so as to provide the number of different blade positions in relation to an aperture in the strip adapted to receive a cable for stripping.

The arrangement therein defined is a most effective and simple means for enabling cable stripping of the kind hereinbefore referred to to be carried out.

The cable stripper described in this earlier Patent is provided with a bush through which the cable is pushed, which extends through the body of the stripper. The bush has an extension protruding beyond the cable exit face of the stripper which is provided to enable the length of cable between successive cuts to be determined by accurately lining up the end of the cable, or a previous cut with the end of the extension of the bush protruding from the body of the stripper.

A generally similar cable stripping tool is disclosed and described in US Patent 3728789 (Fischer). In the case of the stripper disclosed therein however, the length of cable between each cut is determined by means of three adjustable abutment members (screw ends) mounted on a pivotable member for location such as to engage the end of the cable being stripped at a different length from the cutting blade for successive cutting steps.

The arrangement of UK Patent 2173958B, whilst being very effective, does suffer from inflexibility in terms of enabling different lengths of cable between successive cuts to be variably selected, whilst the arrangement of US Patent 3728789 involves the use of a relatively bulky assembly carried on the stripper body, in which adjustment for different lengths between each successive cut is a somewhat laborious and time consuming operation.

It is an object of the present invention to provide a cable stripper in which the above mentioned disadvantages are removed or significantly reduced.

In accordance with the present invention there is provided a cable stripper comprising a casing on which there is disposed a blade carrier, and a blade mounted in the carrier, the blade and blade carrier being associated with means for enabling the provision of a number of different blade positions in relation to a cutting aperture through the stripper adapted to receive a cable for stripping, the casing being provided with a scale on an outer surface thereof carrying a plurality of length markings.

By means of the invention, a user of the cable stripper can lay the end of the cable alongside the scale and, by appropriate selection of markings from the scale, mark at appropriate positions on the cable to provide accurate guidance for cutting the cable. On insertion of the cable into the cutting aperture, by aligning the marks made on the cable with an end of the aperture through the stripper, sequential cuts at appropriate length separation of the cable can be achieved.

The casing preferably comprises two parallel spaced apart plates between which the carrier is pivotally mounted, and between which the aperture extends.

The coaxial cable stripper may be manufactured from metal such as aluminium or it may be made of hard plastic material in which case only the blade may be made of metal and the spring which biases the blade carrier.

The cable stripper may be made of any size required.

A small stripper may be arranged to accommodate cables from, say, 4mm to 10mum external diameter but obviously by making the stripper bigger cables of any size may be accommodated.

In order that the invention may be more readily understood one embodiment thereof will now be described by way of example with reference to the accompanying drawings.

Figure 1 is a plan view of the cable stripping device with the upper of two parallel spaced apart plates removed so as to expose the working parts of the stripper; Figure 2 is a vertical elevation seen from the left hand of Figure 1; Figure 3 is a plan view of a cam stop employed in the stripper shown in Figures 1 and 2; Figure 4 is a section through a portion of the cable stripper showing a bush which receives the cable for stripping and showing the cable in position for making the first cut when stripping it; Figure 5 is a corresponding diagrammatic view of the cam stop in a position corresponding to this first cut; Figure 6 and 7 respectively correspond to Figures 4 and 5 but show the cable position and cam position for the second cut; Figures 8 and 9 again correspond to Figures 4 and 5 but show the cable position and cam position for the third cut;; Figure 10 shows a typical cable end after it has been stripped using the stripper of this invention; and Figure 11 is a side view of the stripping device showing the cable marking scale.

The stripper shown in Figures 1, 2 and 11 comprises a pair of outer plates 1 forming the stripper casing and held together by elongated pins or rivets. A blade carrier 2 is mounted on a pivot 3 and carries a blade 4.

The blade is mounted in a groove and the edges of the groove peened over to hold the blade which has been accurately pre-positioned on initial assembly.

The blade is spring biased by means of a spring 5 so that the angled edge 6 of the blade is biased into a position to cut into a cable when the cable is inserted through a bore of predetermined size to match the cable in a cable guide bush 7. The position of the blade carrier 2 is controlled by means of a rotatable three faced cam stop 8. The cam stop is mounted in apertures in the plates and is held in by an 0 ring and it is provided with a handle 9 so that it may be manually rotated. The three faces of the cam stop 8 are set at different positions relatively to the centre of the cam stop so as to provide three different depths of cut of the blade 4.

The cable 14 is shown in position in the cable guide bush 7 but this can better be seen in Figure 4.

In Figure 4 the guide bush 7 is seen as having a central bore 11 adapted to receive a cable of predetermined diameter. The bush is provided with a slot 12 through which the blade end 4 can extend so as to cut the cable to a predetermined depth.

As can be seen most clearly from Figure 11 one side casing 1 of the stripping device is provided with a scale 13 marked on its side, the scale having variably spaced markings so as to enable the end of a cable 14 to be provided. Before operating the stripper, the user of the tool lays the end of cable 14 alongside the scale and, with a pencil for example makes three pencil markings 15, 16 and 17 corresponding to the desired positions of alignment of the cable with the exit end 29 of guide bush 7 when cutting the cable in order accurately and correctly to strip the cable end.

The cam stop is shown in Figure 3 and in Figure 5 it is shown diagrammatically as a section on line A--A of Figure 3. As seen in Figure 5 it is clear that each of the thee cam faces is differently offset with respect of the centre of the rotatable cam stop.

For the first cut which is the deepest cut required it will be seen that the appropriate cam face is the one which is closest to the centre of the cam stop and is marked 18.

The handle of the cam stop is rotated so as to reach the position marked A in Figure 5 and in this position the face 18 is appropriately located so as to act as a stop restricting the movement of the carrier 2 and therefore restricting the depth of cut of the knife edge 6.

The first cut is the deepest one and is illustrated in Figure 10 as number D. The cable shown in Figure 10 comprises a central copper conducting wire or core 19 around which there is a layer of insulation in the form of a dielectric 20 on which are wound two layers of copper braid 21 followed by an outer cover of plastics material 22. The first cut numbered D is required to cut the full depth of all the outer layers so as to expose a length of conductor 19.The cable is put into the stripper as illustrated in Figure 4, the marking 15 on the cable aligned with the end 29 of guide bush 7, and the blade engaged with the outer conductor of the cable the stripper is then rotated about the cable in an anti-clockwise direction (by use of the operating ring 28) when viewed from the exposed end of the cable, thus enabling the blade to cut to a depth corresponding to the position of the cam face 18 which is also the depth corresponding to the position of the conductor 19. The blade passes through the slot 12 and forms a cut at 23 and this cut corresponds to the position marked D in Figure 10.

The second cut is made by placing the cable 14 in the position shown in Figure 6 with marking 16 aligned with guide bush end 29 so as to make a cut at the position marked 24 in Figure 6. The depth of this cut is restricted by the cam face 25 which has now been positioned as shown in Figure 7 with the handle 9 at position B. This cut corresponds to the position marked E in Figure 10 and cuts through the outer insulation and the two layers of braid but does not cut through the dielectric 20. The third cut is made with the cam stop moved to the position shown in Figure 9 with the handle 9 at position C in which the cam face 27 is the operative one and with the cable positioned as shown in Figure 8 with marking 17 aligned with guide bush end 29 so as to make a cut 26 which corresponds to position F in Figure 10.This cut only cuts through the outer layer of insulation and does not even mark the copper braid layers 21 in Figure 10.

It can thus be seen that by use of this stripper three cuts of accurately controlled depth have been made using the three positions of the cam with the length of cable between each cut accurately determined and controlled.

If a different diameter cable is employed then the cable bush 7 can be replaced by one having a bore of different diameter to receive the cable. Also the cam stop is replaced by one having three differently located cam faces corresponding to the depths required for the new size of cable.

If a cable requires more than three cuts then a cam can be used which has four or five or more cam faces, and more than three markings provided on the cable.

This versatile tool enables many different diameters of cables to be dealt with using the same basic tool but simply replacing the cam stop and cable bush for each diameter of cable (outside diameter) and with various lengths of cable between cuts as may be required for different attachments and connections.

Claims (8)

CLAIMS:

1. A cable stripper comprising a casing on which there is disposed a blade carrier, and a blade mounted in the carrier, the blade and blade carrier being associated with means for enabling the provision of a number of different blade positions in relation to a cutting aperture through the stripper adapted to receive a cable for stripping, the casing being provided on an outer surface thereof with a plurality of length markings.

2. A cable stripper as claimed in Claim 1 in which the length markings are provided by means of a scale on the side of the casing.

3. A cable stripper as claimed in Claim 2 in which the scale is provided on sheet material adhered to the side of the casing.

4. A cable stripper as claimed in Claim 1, 2 or 3 in which the scale has variably spaced markings.

5. A cable stripper as claimed in any one of the preceding claims in which the casing comprises two parallel spaced apart plates between which the carrier is pivotably mounted, and between which the aperture extends.

6. A cable stripper as claimed in any one of the preceding claims formed of metal.

7. A cable stripper as claimed in any one of Claims 1 to 4 formed predominantly of a hard plastic.

8. A cable stripper substantially as shown in and as hereinbefore described with reference to the accompanying drawings.