GB2370426A

GB2370426A - Cable stripping apparatus

Info

Publication number: GB2370426A
Application number: GB0130541A
Authority: GB
Inventors: Nigel Rowcliffe
Original assignee: Antech Ltd
Current assignee: Antech Ltd
Priority date: 2000-12-22
Filing date: 2001-12-20
Publication date: 2002-06-26
Anticipated expiration: 2021-12-20
Also published as: GB2370426B; GB0130541D0

Abstract

A cable stripper 30, such as for stripping a plastics armoured sheath or encapsulation 18 from electric lines, wire ropes and hydraulic lines 15, comprises movable abrasive elements such as a vibrating or rotating block of abrasive material - preferably in the form of pivotally mounted rotatable wire or plastics brushes 32,34 between which a cable 10 is fed. A guard 36 shields the brushes and confines removed encapsulation debris to a collection chamber or hopper 46 for removal. The guard 36 also includes feed guides 38 and exit guides 40 which may incorporate means to grip and propel the cable through the stripper. A forced flow of cooling air from a fan, or conveniently from a pneumatically powered drive means, may dissipate heat generated by the abrasion process.

Description

Cable Stripping Apparatus

This invention relates to cable stripping apparatus, particularly for stripping the encapsulating sheath from heavily armoured cable.

Cable is often used for carrying power and/or signals in subsea applications, particularly in the oil industry, where the cable is subjected to harsh conditions and replacement would be inconvenient and costly. The cable is therefore typically encapsulated by an armoured casing to provide such protection. A typical known cable comprises an electric line, a wire rope, and a hydraulic line in a side-by-side spaced parallel relationship (known as a 'flatback'configuration), encased in a plastics material. The plastics material is commonly known as'encapsulation'. The encapsulation is extruded around the electric and hydraulic lines and the wire rope. Many materials may be used to form the encapsulation, for example Teflon, a polyamide such as nylon, a polyolefin such as polypropylene, or polyvinyliodinefluoride.

Electric and hydraulic power and communications can be transmitted through the electric and hydraulic lines respectively. The wire rope (typically made from steel or stainless steel) provides the cable with extra strength, especially to any tensile forces. The encapsulation protects the electric and hydraulic lines from abrasion that may occur during and after deployment of the cable. Different configurations of electric and hydraulic lines may be used, with several reinforcing wire ropes, or without a wire rope. Other lines

may be included, such as optical and pneumatic lines. Within the encapsulation, the lines are further protected by pressure sheathing layers (again, typi cally steel or stainless steel).

The traditional method of preparing the cable for installation is manual.

The cable is cut to the desired length, and the encapsulation is manually separated from the electric and hydraulic lines and the wire rope at each end of the cable with a knife. The exposed lines may be connected to electric and hydraulic circuits using appropriate junctions and fittings, and the wire rope secured to provide mechanical strength for the cable. Since the encapsulation is tough, cutting it with a knife is difficult and the pressure sheathings around the lines may be cut and damaged. There is also a risk that the person cutting the tube may accidentally cut himself.

A mechanical method of removing the encapsulation has also been developed. In this, a stripping machine draws the cable past cutting wheels which are set to cut into the cable without cutting the lines. Several cutting wheels are provided in order to properly strip the cable. When a different type of cable is to be prepared, the cutting wheels must all be adjusted. If the wheels are incorrectly set, the lines may be cut and damaged.

A method of cleaning electrical conductors is described in US 3 739 415 in which a portable tool is used to clean the ends of conductors by means of two wire brushes mounted pivotally together. Such a device would not be suitable for complete removal of tough, heavy-duty encapsulation.

It is an object of the present invention to provide a convenient means for stripping a cable of its encapsulation.

According to its main aspect the present invention provides a cable stripper for removing encapsulation from cable including conduit means, the stripper comprising : moveable abrasive means; drive means operable to abrasively engage the abrasive means and the cable; a guard means for shielding the abrasive means; and support and guidance means for supporting and/or guiding the cable relative to the moveable abrasive means; such that when the abrasive means and the cable are abrasively engaged, encapsulation is removed from the cable without significantly abrading the conduit means.

Cable strippers embodying the invention will now be described, by way of example, and with reference to the accompanying drawings, in which: Fig. I is a perspective view of a piece of cable; Fig. 2 is a partly sectional side elevation of the cable stripper operating on some cable; Fig. 2a is a partly sectional side elevation of the cable stripper with an alternative debris collector; Fig. 3 is a schematic side elevation of part of the mechanism of the cable stripper; and Fig. 4 is an end view of a further cable stripper.

Fig. 1 shows a known cable 10 comprising an electric line 12, a wire rope 14 and a hydraulic line 16 in a side-by-side spaced parallel relationship (a 'flatback'configuration), encased in a plastics material 18. The encapsulation is extruded around the lines 12,16 and wire rope 14. Within the encapsulation 18, the lines are further protected by pressure sheathing layers 22.

Fig. 2 shows the cable stripper 30, which comprises a pair of rotatable wire brushes 32,34 rotated by a drive motor (not shown), and a sheathing 36 which includes feed guides 38 and exit guides 40.

In order to remove the encapsulation from the end of a cable to leave the lines and wire rope (denoted generally here as 15) accessible, the cable 10 is introduced to the cable stripper 30 through the feed guides 38. The wire brushes 32,34 are caused to rotate at high speed whilst the cable stripper is moved along the cable (shown by arrow'a'), so that the introduced end of the cable passes between the wire brushes.

The materials of the pressure sheathing around the cable's lines and the material of the wire rope 14 are both harder than the material of the encapsulation 18. The material from which the wire of the wire brushes 32 and 34 is made has a hardness intermediate to that of the pressure sheathing and wire rope 14 on the one hand and that of the encapsulation 18 on the other.

As the cable stripper 30 is moved along the cable and the cable 10 passes between the rotating wire brushes, the encapsulation, being a softer material than that of the wire of the brushes, is abraded or cut into small pieces

42, and so removed from the cable. The pressure sheathing and the wire rope 14, being harder materials than the wire of the brushes 32, 34, are not abraded to a significant extent and remain intact. Therefore as the cable 10 passes between the rotating wire brushes 32 and 34, the lines and the wire rope 14 emerge separated and stripped of the encapsulation 18. The stripped lines and wire rope then leave the cable stripper through the exit guides 40.

The wire of the wire brushes may be made from, for example, steel, stainless steel or brass. The resilience and/or deformability of the strands of wire of the wire brushes effectively reduces the hardness of the wire brushes, so that even when the wire brushes are formed from material the same as or similar to the wire rope and pressure sheathings, the relatively thick and rigid structures of the wire rope and pressure sheathings are not significantly abraded.

When the required length of lines and wire rope 14 has been exposed, the drive motor to the wire brushes is switched off and the cable stripper 30 is moved back along the cable 10 (i. e. to the left in the figure) to free the cable. Alternatively, the cable stripper 30 shown in Fig. 4 may be moved sideways away from the cable, with the cable exiting by the sideways slot. The stripper can then be switched off.

To enhance the abrasion of the encapsulation, the wire brushes are rotated so that at the point where the ends of the wire brushes contact the encapsulation, the ends are moving against the advancing movement of the cable (i. e. in the figure, the cable is moving from the right hand side to the left

hand side, whilst the upper brush is rotating anticlockwise and the lower brush is rotating clockwise). The pieces of encapsulation thrown up from the wire brushes are confined by the housing 36 and collected in a collection chamber 44, where they settle and may be periodically emptied. Alternatively, as shown in Fig. 2a, a collection hopper 46 may be attached to the housing 36 to conduct the debris to a separate attachable repository, such as a bag.

Fig. 4 shows a cable stripper with drive means in the form of an air motor 72 with an air inlet 76 and an exhaust air outlet 78. The motor drives the brushes 32,34 by means of gears and corresponding drive shafts 74. The exhaust air outlet is directed by means of a nozzle 80 to the area of abrasion close to the contact area between the brushes and the cable. This serves to cool the corresponding surfaces of the brushes and the cable and also serves to clear away the resulting debris. In this embodiment a side access 82 is provided into which the cable can be located sideways at the place on the cable where the encapsulation is required to be removed.

The brushes are spaced so that the ends of the brushes reach around lines and wire rope. Unlike the spacing of cutting wheels of prior art systems, the spacing of the wire brushes is not critical, since the wire of the brushes is incapable of abrading the wire 14. Further, with the Fig. 3 mechanism, the brushes will deflect away from the wire such that, in combination with the effect of the restoring spring 60, a constant restoring force or pressure is applied between the brushes and the cable 10. The housing surrounding the wire brushes ensures that those using the cable stripper cannot be hurt by the

rotating wire brushes or by the pieces of encapsulation released by the action of the brushes.

The wire of the brushes will itself be gradually abraded, particularly by the harder material of the pressure sheathing and the wire rope of the cable. The wire brushes may be periodically moved closer together to counter this effect. This may be achieved by the mechanism shown in Fig. 3. In this mechanism, the rotating wire brushes 32,34 are supported on respective arms 52, 54 each supported on its own corresponding pivot 56,58. Each arm is free to swing about its pivot, allowing the rotating wire brushes to move towards and away from each other subject to the restoring force of the spring 60. The spring 60 is shown as a single spring joining the two arms 52,54 to indicate that the same restoring force is applied to each arm, but in practice each arm will preferably have its own restoring spring.

The material used for the wire for the wire brushes is typically a metal, but could be, for example, a plastics material having the correct hardness. Rather than a wire brush, some other mass of abrasive material having a hardness intermediate to that of the encapsulation and the cable lines and ropes could be used, for a example a rotating cylindrical block of material or a vibrating block of material.

The brushes will therefore apply an even pressure to the cable, resulting in an even removal of encapsulating material and also accommodating irregularities in the cross section of the cable and/or wire. The arrangement of the brushes and the pivots on the supporting arms is such that the stripper can

also accommodate bent cable and still provide even removal of the encapsulating material. This even pressure prevents damage to the cable 10 and also prevent the build up of heat which can damage the cable, the encapsulation 18, and the stripper 30 itself.

The cable stripper may also be moved along the cable, without the brushes rotating, to a particular region between the two ends of the cable. The wire brushes may then be caused to rotate, and a region of encapsulation partway along the wire removed. Exposing the lines at particular regions along the cable allows a greater flexibility in connecting devices and junctions to the lines of the cable. For example, it becomes straightforward to supply power to a string of devices; previously this would usually be achieved by means of several separate pieces of cable between the devices, since to attach further devices in positions along a cable would not have been cost effective.

Alternatively, using the stripper of Fig. 4, the cable can be introduced to and positioned within the stripper by means of the side slot.

The cable stripper could also be arranged to open or have a side feed such that the cable may be placed in the cable stripper without having to first feed the end of the cable into the stripper and moving the stripper along the cable until the desired point is reached. Such a cable stripper could also be used to expose lines along the length of a cable whose two ends are already both attached to junctions and/or fittings.

For a given cable, the speed with which the cable stripper may be moved along the cable to strip the encapsulation will depend principally upon

the material of the wire brushes and the speed of rotation. Different cables may require the material of the wire brushes and their speed of rotation to be varied. If however it is found that the cable stripper has been moved along the cable at too high a speed and encapsulation remains, the process may simply be repeated.

Naturally, the cable stripper may be fixed and the cable fed through it.

The guides could then incorporate some grip means to propel the cable through the cable stripper. The feed guide may have a larger aperture than the exit guide, since the stripped cable leaving the cable stripper will have a smaller diameter. Alternatively, the guides could include a resilient flexible material.

Naturally, any cable with an encapsulation softer than that of the cable's lines, wire ropes, line sheathings, etc. is amenable to stripping in this manner.

Claims

1 A cable stripper for removing encapsulation from cable including conduit means, the stripper comprising: moveable abrasive means; drive means operable to abrasively engage the abrasive means and the cable; a guard means for shielding the abrasive means; and support and guidance means for supporting and/or guiding the cable relative to the moveable abrasive means; such that when the abrasive means and the cable are abrasively engaged, encapsulation is removed from the cable without significantly abrading the conduit means.

2 A stripper according to claim 1 wherein the abrasive means comprise first and second independently, pivotally mounted abrasive elements.

3 A stripper according to claim 2 wherein the moveable abrasive elements comprise rotatable wire brushes.

4 A stripper according to claim 3 wherein the brushes are positioned such that their axes of rotation are parallel and the cable passes between them.

5 A stripper according to either of claims 3 and 4 wherein the brushes rotate so as to oppose the movement of a cable introduced to the stripper.

6 A stripper according to any of claims 2 to 5 including a collection chamber for collecting the abrasion debris.

7 A stripper according to claim 7 wherein the collection chamber is accessible for removal of the abrasion debris.

8 A stripper according to any of claims 2 to 7 including wherein the guidance and support means includes an entrance guide supporting and/or guiding the cable before it contacts the brushes and an exit guide supporting and/or guiding the cable after it contacts the brushes.

9 A stripper according to any of claims 2 to 8 including guard means for shielding the brushes.

10 A stripper according to claim 9 wherein the guard means comprise a substantially cylindrical housing within which the brushes are positioned.

11 A stripper according to claim 10 wherein the axis of the substantially cylindrical housing is parallel to that of the axes of rotation of the brushes.

12 A stripper according to any of claims 2 to 11 wherein a forced flow of cooling air is provided to dissipate the heat generated by the abrasion.

13 A stripper according to claim 12 in which the drive means is pneumatically powered, the forced flow of cooling air being provided by directing the exhaust air from the air drill to the region of abrasion.

14 A stripper according to claim 12 in which the drive means is an electric motor and the forced flow of cooling air is provided by a fan.

15 A stripper according to claim 14, where in the forced flow of cooling air is directed away from the drive means.

16 A stripper for removing encapsulation substantially as herein described and illustrated.

17 A cable including conduit means surrounded by a softer encapsulation, some or all of the encapsulation having been removed by the stripper of any previous claim.

18 An encapsulated cable according to claim 17 wherein the encapsulation is removed between two regions of the cable where the encapsulation is not removed.

19 A stripped cable substantially as herein described and illustrated.

20 Any novel and inventive feature or combination of features specifically disclosed herein within the meaning of Article 4H of the International Convention (Paris Convention).

Amendments to the claims have been filed as follows 1 A method of removing encapsulation from flat cable having a plurality of lines therein comprising: driving a moveable abrasive means, shielded by guard means, the abrasive means comprising rotatable wire brushes; and supporting and/or guiding the cable relative to the said moveable abrasive means means, for movement therebetween.

2 The method according to claim 1 wherein the abrasive means comprise first and second independently, pivotally mounted abrasive elements.

3 The method according to any preceding claim wherein the brushes are positioned such that their axes of rotation are parallel and the cable passes between them substantially perpendicular to their axes.

4 The method according to any preceding claim wherein the brushes rotate so as to oppose the movement of a cable passing between them.

5 The method according to any preceding claim wherein debris is collected in a collection chamber.

6 A method according to claim 5 wherein the collection chamber is accessible for removal of the abrasion debris.

**WARNING** end of CLMS field may overlap start of DESC **.

**WARNING** start of DESC field may overlap end of CLMS **.

8 A method according to any preceding claim wherein the guidance and support means includes an entrance guide supporting and/or guiding the cable before it contacts the brushes and an exit guide supporting and/or guiding the cable after it contacts the brushes.

9 A method according to any preceding claim wherein the guard means comprise a substantially cylindrical housing within which the brushes are positioned.

10 A method according to claim 9 wherein the axis of the substantially cylindrical housing is parallel to that of the axes of rotation of the brushes.

11 A method according to any preceding claim wherein a forced flow of cooling air is provided to dissipate the heat generated by the abrasion.

12 A method according to claim 11 in which the drive means is pneumatically powered, the forced flow of cooling air being provided by directing the exhaust air from the air drill to the region of abrasion.

13 A method according to claim 11 in which the drive means is an electric motor and the forced flow of cooling air is provided by a fan.

14 A method according to claim 13, wherein the forced flow of cooling air is directed away from the drive means.

**WARNING** end of DESC field may overlap start of CLMS **.

**WARNING** start of CLMS field may overlap end of DESC **.

14 A method according to claim 13, wherein the forced flow of cooling air is directed away from the drive means. 15 A method of stripping insulation from flat cable substantially as herein described and illustrated.

**WARNING** end of DESC field may overlap start of CLMS **.

**WARNING** start of CLMS field may overlap end of DESC **.

15 A method of stripping insulation from flat cable substantially as herein described and illustrated.