GB2173958A - Coaxial cable stripper - Google Patents

Abstract

A cable stripper is provided to strip cables of different diameters using a simple hand tool with a replaceable blade carrier. The tool comprises a blade carrier B which has a blade C adapted to cut into and strip a cable. The carrier B is spring biased against the cam stop H which has three different cam faces thus enabling the position of the carrier to be varied according to the depth of cut required. The cam stop and the cable bush may be provided in interchangeable sets so that for a different diameter of cable a new bush is put in and a new cam stop with different cam face positions. <IMAGE>

Description

SPECIFICATION Coaxial cable stripper This invention relates to a cable orwire 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 forthe 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 ortwo layers of outer conductors.

Overtheouterconductorthere 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 ofthe end portion ofthe cable.

This requires very accurate cutting and stripping so as to avoid damaging the central conductor, the dielectric and 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.

As 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 accordance with the invention a cable stripper comprises a casing on or in 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 a number of different blade positions in relation to an aperture in the stripper adapted to receive a cable for stripping.

The aperture may be formed as a bore in a removable bush so that, by replacing the bush by one with a different sized bore, different diameter cables may be stripped.

The cam stop may be formed as a removable member again in bush likeform,so that different depths of cut may be provided for different diameter cables by replacing the cam stop removable member by one with differently dimensioned cam faces.

Preferably there are provided a set of interchangeable cam stops matched with a corresponding set of interchangeable bushes each bush having a bore of a diameter to receive a cable of predetermined diameter and thus to provide the desired cable receiving aperture in the casing, each corresponding cam stop having cam faces dimensioned to provide appropriate depth of cut for said cable or predetermined diameter.

The cam stops may be rotatably mounted in an aperture in the carrier so that it may be manually moved to any one ofsaythree positions forthe blade carrier.

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

The blade itself may be mounted in a suitable channel in the carrier. It may be held in position by peening over the edges ofthe channel.

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

The cabie stripper may be made of any size required. A small stripper may be arranged to accommodate cables from, say, 4mm to 1 Omm external diameter but obviously by making the stripper bigger and adjusting the sizes of the bushes and cam stops cables of any size may be accommodated.

Cam surfaces may be very accurately determined thereby determining with equal accuracy the position ofthe blade relatively to the cable so asto make sure that the depth of cut is exactly that required for the particular cutting operation being performed.

In the accompanying drawings:- Figure lisa plan ofthe cable stripping device with the upperoftwo parallel spaced apart plates removed so asto 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 diagrammaticview of the cam stop in a position corresponding to this first cut; Figures 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 positionforthe third cut; and Figure 10 shows a typical cable end after it has been stripped using the stripper ofthis invention.

Thestrippershown in Figures 1 and 2 comprises a pair of outer plates Aforming the stripper casing and held together by elongated pins or rivets. A blade carrier B is mounted on a pivot pin D and carries a blade C. The blade is mounted in a groove and the edges ofthe 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 F so that the angled edge E ofthe 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 G. The position ofthe blade carrier B is controlled by means-of a rotatable three faced cam stop H. 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 K so that it may be manually rotated. The three faces of the cam stop H are set at different positions relativelyto the centre ofthe cam stop so as to provide three different depths of cut of the blade C.

The cable J is shown in position in the cable guide bush G butthis can better be seen in Figure 4.

in Figure 4the guide bush G is seen as having a central bore L adapted to receive a cable or predetermined diameter. The bush is provided with a slot M through which the blade end E can extend so as to cut the cable to a predetermined depth.

The bush also has an extension N which is provided to enable the first cutto be determined accurately by lining up the end ofthe cable 0 with the end ofthe extension N as shown in Figure 4.

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 clearthat each ofthe three cam faces is differently offset with respect of the centre of the rotatable cam stop.

Forthefirst cut which is the deepest cut required it will be seen thatthe appropriate cam face is the one which is closestto the centre ofthe cam stop and is marked P.

The handle ofthe cam stop is rotated so as to reach the position marked 1 in Figure 5 and in this position the face P is appropriately located so as to act as a stop restricting the movement of the carrier B and therefore restricting the depth of cut of the knife edge E.

Thefirstcut is the deepest one and is illustrated in Figure 10 as number 1. The cable shown in Figure 10 comprises a central copper conducting wire or core S around which there is a layer of insulation in the form of a dielectricT on which are wound two layers of copper braid U followed byan outer cover of plastics material V. The first cut numbered 1 is required to cut the full depth of all the outer layers so as to expose a length of conductor S.When the cable 0 is put into the stripperas illustrated in Figure 4 and the blade engaged with the outerconductor of the cablethe stripper is then rotated about the cable in an anticlockwise direction when viewed from the exposed end ofthe cable, thus enabling the blade to cut to a depth corresponding to the position ofthe cam face P which is also the depth corresponding to the position of the conductor S. The blade passes th rough the the slot N and forms a cut atW and this cut corresponds to the position marked 1 in Figure 10.

The second cut is made by placing the cable 0 in the position shown in Figure 6so as to make a cut atthe position marked X in Figure 6. The depth ofthis cut is restricted bythe cam face Owhich has now been positioned as shown in Figure 7. This cut corresponds to the position marked 2 in Figure 10 and cuts through the outer insulation and the two layers of braid but does notcutthrough the dielectricT. The third cut is made with the cem stop moved to the position shown in Figure 9 in which the cam face R is the opertive one and with the cable positioned as shown in Figure 8 so as to make a cutYwhich corresponds to position 3 in Figure 10. This cut only cuts through the outer layer of insulation and does not even markthe copper braid layers U in Figure 10.

It can thus be seen that by use ofthis stripperthree cuts of accurately controlled depth have been made using the three positions ofthe cam.

If a different diametercable is employed then the cable bush G can be replaced by one have a bore of differentdiameterto receivethecable. Also the cam stop is replaced by one having three differently located cam faces corresponding to the depths required forthe new size of cable.

If a cable requires more than three cuts then a cam can be used which has four orfive or more cam faces.

This versatile tool enables many different diameters of cables to be dealt with using the same basictool but simply replacing the cam stop and cable bush for each diameterofcable (outside diameter).

The blade when worn may easily be replaced. For this purpose the blade pivot pin may be made as a removable item so thatthe blade carrier can be taken out and the blade and carrier replaced as a whole.

Itwill be seen in Figure2thatthecam stop is retained in position by an '0' ring Z and this 'O' ring is on the outside ofthe adjacent plate A. The reason for locating the '0' ring on the outside ofthe plate is to ensure thatthe cam stop is freely rotatable and yet is held in position in the plates A.

When the blade is mounted in the carrier it is placed in the channel in the carrierwhich is, say, 10/1000 of an inch (2S.4x 10-3cm) deeper than the thickness ofthe blade. The blade is accurately located in a pre assemblyjig so as to correctly position the knife edge ofthe blade and is held in position by glue temporarily. When it is properly positioned the edges ofthe channel are peened overto hold the blade in position.

Other methods may be used for mounting the blade as desired.

Claims (8)

1. Acablestrippercomprisingacasingonwhich is pivoted a blade carrier, a blade mounted in said 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 a number of different blade positions in relation to an aperture in the stripper adapted to receivea cableforstripping.

2. Astripper according to claim 1 and in which the aperture is formed as a bore in a removable bush so that, by replacing the bush by one with a different sized bore, different diameter cables may be stripped.

3. A stripper according to claim 1 or claim 2 and in which the cam stop is formed as a removable member so that different depths of cut may be provided, for different diameter cables, by replacing the cam stop removable member by one with differentlydimen- sioned cam faces.

4. A stripper according to claim 1 in combination with a set of interchangeable cam stops matched with a corresponding set of bushes each bush having a bore of a diameterto receive a cable of predetermined diameter and thus to provide the cable receiving aperture,and each corresponding cam stop having cam faces dimensioned to provide appropriate depths of cut for said cable of predetermined diameter

5. A stripper according to any preceding claim and in which the or each cam stop is adapted to be rotatably mounted in an aperture in the carrier.

6. A stripper according to any preceding claim and in which the casing comprises two parallel spaced apart plates between which said carrier is pivotally mounted.

7. A stripper according to any of claims 1 to 6 in which the blade is mounted in a channel in the carrier and the whole assembly is replaceable.

8. A cable stripper substantially as herein before particularly described and as illustrated in the accompanying drawings.