WO2004035455A2

WO2004035455A2 - Apparatus

Info

Publication number: WO2004035455A2
Application number: PCT/GB2003/004348
Authority: WO
Inventors: Alexander Charles Crawford
Original assignee: Deep Tek Limited
Priority date: 2002-10-15
Filing date: 2003-10-07
Publication date: 2004-04-29
Also published as: GB0223965D0; WO2004035455A3; AU2003274309A1

Abstract

A method and apparatus for handling a load is disclosed which is capable of raising and lowering, or of towing, a load and also handling service cables (2) and/or hoses connected to the load. The device has a guide means (30) for guiding the rope (1), and a bearing device (32) for the guide means. The bearing device is typically located between the wrapping device (3, 5, 9) and the guide means to isolate the wrapping device from the torque applied to the guide means by the rope.

Description

"Apparatus"

This invention relates to apparatus for use in handling a load which is capable of raising and lowering, or of towing, a load and also handling service cables and/or hoses connected to the load. The invention is particularly, but not exclusively, applicable to the handling of subsea equipment such as grabs .

Providing services to underwater equipment often involves the provision of a specific bundle of cable (s) and/or hose(s) dedicated to each application. For some applications, it is known to incorporate the service bundle within an armoured hoist rope. This approach has a number of deficiencies. The resulting rope is costly, gives inferior hoisting properties, and by virtue of limitations on the diameter of rope which can be handled the services which can be incorporated are limited. Further, in practice it is impossible with this arrangement to add to the length of the rope or to join different types of materials, for example wire ropes with fibre ropes.

To avoid the necessity of using the expensive armoured hoist rope, it is known to wind a service cable around a rope, or vice versa, to service underwater equipment. The service cable is generally wound around the rope from a winder drum on a rotatable arm. The arm is typically powered by a motor, and winding the arm around the rope as the rope is lowered twists the service cable around the rope. Rollers/sheaves or other guides at the lowest part of the winding apparatus position the twisted service cable and rope and prevent it from bearing directly on other parts of the apparatus. The rollers/sheaves/guides are typically in the form of a cage enclosing the rope and are typically attached to and rotate with the winder arm or drum.

However, when these devices are used on a ship, currents and movement of the ship cause the service cable and rope combination to stream out behind the ship, often at an angle. This pulls the service cable and the rope into a corner of the rollers/sheaves, and it becomes difficult to rotate the arm or drum.

According to an aspect of the present invention there is provided apparatus for use in handling a load comprising a load-bearing rope, a mechanism for paying out and recovering the rope, a service cable and a service cable holder for holding the service cable, a wrapping device for rotating one of the service cable and the rope around the other as they are paid out to wrap the two together, and to unwrap them as they are recovered, a guide means for guiding the rope, and a bearing device for the guide means .

Certain embodiments of the invention facilitate the movement of the winder arm or drum, reduce tension on the service cable, and reduce complications with self-tensioning devices commonly used on the cable winch drum to tension the service cable on the rope.

The term "service cable" is used herein to denote a flexible elongate member used for conveying power or data, such as an electrical cable, a fibre optic cable, or a pneumatic or hydraulic hose.

The bearing device typically enables independent rotation of an arm or drum of the wrapping device, even if the guide means cannot move (e.g. because of the rope pulling on the guide means) .

Typically, the guide means comprises at least one roller or sheave. Preferably, more than one roller or sheave is provided. Optionally, four rollers are provided around the circumference of the rope forming a roller cage which encloses the rope. The rollers can form an arcuate inner surface for bearing against the rope in preferred embodiments. Typically, the wrapping device comprises a service cable drum being arranged for rotation about a drum axis which coincides with the axis of the rope. The cable may be guided by sheaves or pulleys from the drum. Instead of rotating on its axis, cable drum may be static and may have a winding device rotating around it to pay out the service cable. Preferably, the service cable drum has a central aperture through which the load-bearing rope passes.

The service cable drum may be rotatably mounted on a structural member so that its axis is not co- incident with the axis of the rope, and so that it is moved in a circular path around the axis of the rope as the cable is being paid out or recovered. Sheaves and/or pulleys may again guide the cable as it is being paid out or recovered. The axis of the service cable drum in such embodiments can be vertical so that it is parallel to the axis of the rope, or horizontal, so that it is perpendicular to the axis of the rope.

Most preferably, the cable drum has an axis which coincides with the axis of the rope, the cable drum typically having a central aperture through which the rope passes, with the service cable passing over a cable sheave which is mounted for movement in a circular path around the axis of the rope.

Typically, the mechanism for paying out and recovering the rope includes a rope winch, from which the rope passes over a rope sheave and thereafter extends to the load along a substantially straight axis.

Optionally, the rope winch, the cable drum, and the wrapping device each have a respective driving motor. Alternatively, the rope winch, the cable drum and the wrapping device are driven by a single source through appropriate mechanical linkages.

Typically, the service cable is paid out close to the axis of the rope.

Preferably, the apparatus also includes a mechanism for holding and paying out a second or further cable, and a second wrapping device for wrapping the second or further cable around the rope and the first cable as the second cable is paid out, to wrap the second cable around the entwined first cable and rope, and to unwrap the second cable from the first cable-hoist rope combination as they are recovered.

Typically, the mechanism for holding and paying out the second or further cable includes a rotating arm; preferably the arm has spooling gear. Typically, the arm rotates around the rope and the first service cable. Preferably, the arm rotates around the rope in the opposite direction to the direction of rotation of the first service cable arm; it would be possible, however, for the second or further cable to be wound on in the same direction as the first service cable, optionally at a different pitch. Preferably, the arm has a guide sheave to hold the securing rope radially outward of the service cable sheave and the service cable.

Typically, the service cable comprises an electrical cable, a fibre optic cable, a pneumatic cable or a hydraulic hose.

Preferably, the load-bearing rope is a hoist rope used for raising and lowering a load. Typically, the load-bearing rope is a rope adapted for paying out, towing and recovering a load.

Optionally, more than one service cable is provided, each extending from a respective drum.

The invention also provides a method of handling a load, the method comprising the steps of: paying out a load-bearing rope; paying out a service cable; wrapping one of the load-bearing rope and the service cable around the other as they are being paid out; and subsequently unwrapping the service cable and the rope from one another as they are being recovered; wherein one of the rope and the cable are paid out through a bearing device.

Examples of apparatus and a method for use in handling a load in accordance with the invention will now be described with reference to the drawings, in which:- Fig. 1 is a schematic perspective view illustrating the principle of operation of a first example of the invention; Fig 2 is a more detailed side view, partly in section, of an apparatus used in the example of Fig. 1 having a guide means in the form of a roller cage and a cable drum with its axis vertically aligned; Fig. 3 is a side view of the embodiment of Fig. 2, also showing a second arm and second cable; Fig. 4 is a side view of an embodiment similar to Fig. 3, having guide means in the form of guide sheaves; Fig. 5 is a schematic perspective view of the embodiment of Fig 3 ; Fig. 6 is a schematic perspective view illustrating an alternative embodiment of the invention; Fig. 7 is a side view of the invention having a guide means in the form of a roller cage and a cable drum with its axis horizontally aligned; Fig. 8 is a side view similar to that of Fig 7, having a guide means in the form of sheave guides; Fig. 9 is a schematic perspective view illustrating an embodiment similar to that of Fig. 1 but modified for towing rather than lifting; and Fig. 10 is a schematic perspective view illustrating an embodiment similar to that of Fig. 6 but modified for towing rather than lifting. Referring to Fig. 1, a hoist rope 1 extends from a hoist rope winch' 13 over a hoist rope sheave 4 to support a load (not shown) for raising and lowering. The hoist rope 1 may be any suitable form of hoist rope such as flexible steel wire rope or preferably a synthetic fibre rope, for example of "Kevlar" . A service cable 2 is reeled on a service cable drum 3 and extends to the load via a service cable sheave 5.

The hoist rope 1 passes through a central aperture of the service cable drum 3, and the service cable sheave 5 is arranged to be driven circumferentially around the axis of the service cable 1. By co- ordinating the movements of the hoist rope winch 13, the service cable drum 3 and the service cable sheave 5, the service cable 2 can be wrapped helically around the hoist rope 1 as the load is lowered, and unwrapped as the load is raised. In this way, a hoist rope of any desired properties can be used in combination with any required service connection.

Fig. 2 shows the service cable drum 3 and associated parts in greater detail . The cable sheave 4 is journalled to a fixed frame 20 that is secured to any suitable supporting structure such as an A frame (not shown) . The service cable drum 3 is rotatably mounted on the lower part of the frame 20 and driven in rotation by a motor 6. The inner end of the service cable 2 can be connected to any appropriate service if needed by any convenient means (not shown) but is otherwise connected to the cable drum 3. The service cable sheave 5 is journalled on a mounting frame 9 that is rotatable about the fixed frame 20 by means of a motor 7.

The motors 6 and 7 are driven at speeds related to the axial speed of the hoist rope 1. The speed correlation may be fixed. Preferably, however, this correlation will be controllable to alter both the length of twist (pitch) of the lay of the service cable 2 on the hoist rope 1, and the tension in the service cable 2.

The rope 1 extends downwards through the apparatus through a roller cage 30. The roller cage 30 is typically composed of four rollers, positioned at right angles to each other, defining a square central hole, through which the rope 1 passes. Between the roller cage 30 and the drum 3 is a bearing 32, which allows the frame 9 and the cable drum 3 to rotate independently of the roller cage 30. The bearing 32 could consist of bearings in a bearing race, or it could simply be two plain bearing surfaces.

Fig 3 shows an embodiment similar to that of Fig. 2, but also having a second service cable 17, which is wound around the hoist rope 1. This second service cable is stored in a second drum 44, which is located on top of a L-shaped arm 34 mounted for rotation about the hoist xope 1. The second cable 17 is guided over the end of the arm 34 by rollers/guide sheaves 14. The arm 34 may be rotated in the same, or a contrary direction to the frame 9.

Fig 4 shows an embodiment similar to that of fig 3. However, in this embodiment, the roller cage 30 is replaced by guide sheaves 42. There are typically at least two guide sheaves 42 facing one another to capture the rope between the grooves of the sheaves. The other difference is that the second drum 44 holding the second service cable 17 is coaxial with the axis of the rope 1 and is positioned directly on top of the cable drum 3. In this embodiment the sheaves 42 are mounted on the bearing which allow the sheaves 42 to rotate independently of the drum 3 to follow the rope 1 if it pulls to one side.

Fig 5 shows a modification in which a second service cable 17 is wrapped around the hoist rope 1 along with the service cable 2. In this modification, the service cables 2, 17 are each provided with a respective storage drum 15, 16 and a respective sheave 5, 50 which may suitably be carried on a common supporting frame for rotation in unison. The apparatus may be further modified by adding further drums and sheaves to handle more services.

The second sheave 50 could be rotatable independently of (and optionally in the opposite direction to) the first sheave 5. The second cable 17 could be an additional service cable to wind around the rope 1.

Fig. 6 illustrates a second example in which the service cable 2 is reeled on a drum 3 and the drum 3 is itself rotated about the hoist rope 1 to achieve a helical wrap and unwrap. As with the first example, the example shown in Fig. 6 could be modified by adding further service cable drums to be rotated by the motor 10.

Fig. 7 shows a more detailed view of part of Fig. 6. The service cable drum 3 is rotatably mounted on a first arm 18 for rotation around the rope 1. Rotation of the arm 18 is powered by the motor 10.

The rope 1 extends downwards through the apparatus through a roller cage 30, typically composed of four rollers set at right angles to each other. The roller cage 30 has a square hole in the centre, through which the rope 1 passes. Above the roller cage 30 is a bearing 32, which allows the first arm 18 to rotate independently of the roller cage 30. The bearing 32 could be bearings in a bearing race, or simply two bearing surfaces. Ball bearings are used in this example, but roller bearings could be used instead.

A second cable 36 is supported by a second drum 38 mounted on the end of a rotatable second arm 35. The second arm 35 may be rotatable independently of (and optionally in the opposite direction to) the first arm 18. The second cable 36 could be an additional service cable to wind around the rope 1.

Fig. 8 shows an alternative embodiment of part of Fig. 6, having guide sheaves 42 instead of the roller cage 30 of Fig. 7. Again, there are typically at least two guide sheaves 42 set facing one another to capture the rope 1 in the same manner as previously described with respect to the Fig. 4 embodiment. Here the sheave block is connected to the drum by means of the bearing. Instead of the second drum 38 being mounted on the end of arm 35, in this embodiment it is mounted on the top of arm 35 and the second cable 36 is guided over the outer edge of the arm by guides 49, typically rollers or guide sheaves, so that the second cable 36 leaves the apparatus radially outward of the service cable 2.

Fig. 9 illustrates the example of Fig. 1 modified for use in a marine towing application, for example in paying out, towing and recovering a sensor array such as a sonar sensor or seismographic surveying sensor, the sensor array being towed underwater or on the surface. The service cable drum 3 is hinged to the main structure of the towing vessel (not shown) and can be tilted to a desired towing angle by hydraulic or other mechanisms. Likewise, Fig. 10 illustrates the modification of the example of Fig. 6 for the same use, the frame carrying the mounting arm for the service cable drum 3 being hinged to the vessel and tilted to the desired angle by hydraulic or other mechanisms.

Embodiments of the invention may be applied to a system in which one or more service cables is applied to a load-bearing rope which itself carries a service channel in addition to fulfilling its load-bearing function. For example, the load- bearing rope could be a steel wire rope carrying electrical signals, or a rope comprising "Kevlar" load-bearing strands in combination with optical fibre cable.

Other modifications may be made within the scope of the invention. For example, the positions of the rope and the service cable could be reversed so that the rope is on a drum and the cable is fed from a winch, to wind the rope around the service cable. When tension is put on the rope, the rope straightens and the service cable becomes wound around the rope in any case.

The bearing 32 does not have to be mounted above the roller cage 32; the bearing could be radially outward of the roller cage 30, or in another position.

Many cable drums could be provided: in Fig. 1, they could be stacked on top of each other; in Fig. 6 there could be many arms extending radially outwards from the rope axis, each with a respective cable sheave. Further rollers and/or guide sheaves could be used to conveniently position the cable relative to the rope, e.g. to deflect one away from the axis of the other, or to pass the cable around the lip of an arm to align the cable with the rope.

In some embodiments, the guide means may comprise both rollers and guide sheaves. For example, the roller cage 30 (shown in Figs. 3 and 7) could be provided in conjunction with guide sheaves 42 (shown in Figs. 4 and 8). Alternatively, combinations such as two rollers and two guide sheaves could be used.

Claims

Claims :

1 Apparatus for use in handling a load comprising a load-bearing rope, a mechanism for paying out and recovering the rope, a service cable and a service cable holder for holding the service cable, a wrapping device for rotating one of the service cable and the rope around the other as they are paid out to wrap the two together, and to unwrap them as they are recovered, a guide means for guiding the rope, and a bearing device for the guide means.

2 Apparatus as claimed in claim 1, wherein the guide means comprises at least one friction-reducing device selected from the group comprising a roller device, a sheave, and a wheel.

3 Apparatus as claimed in claim 2, wherein more than friction-reducing device is provided.

4 Apparatus as claimed in claim 2 or claim 3, wherein friction-reducing devices are provided around the circumference of the rope.

5 Apparatus as claimed in claim 2, 3 or 4 , wherein the friction-reducing devices present an arcuate inner surface against which the rope bears in use.

6 Apparatus as claimed in any one of claims 2-5, wherein the guide means comprises a roller cage. 7 Apparatus as claimed in any preceding claim, ^' wherein the bearing device comprises a bearing race.

8 Apparatus as claimed in claim 7, wherein the bearing device has roller bearings .

9 Apparatus as claimed in claim 7, wherein the bearing device has ball bearings.

10 Apparatus as claimed in claim 7, wherein the bearing device has a plain bearing surface.

11 Apparatus as claimed in any preceding claim, wherein the bearing device is disposed between the wrapping device and the guide means.

12 Apparatus as claimed in claim 11, wherein the bearing device surrounds the guide means.

13 Apparatus as claimed in any preceding claim, wherein the bearing device surrounds the rope and permits the rope to rotate within with respect to the apparatus without transferring rotational forces to all of the apparatus.

14 Apparatus as claimed in any preceding claim, wherein the wrapping device rotates a service cable drum about a drum axis which coincides with the axis of the rope.

15 Apparatus as claimed in any one of claims 1-13 wherein the service cable holder is static and has a winding device rotating around it to pay out the service cable.

16 Apparatus as claimed in any preceding claim, wherein the apparatus also includes a mechanism for holding and paying out a second or further cable, and a second wrapping device for wrapping the second ' or further cable around the rope and the first cable as the second cable is paid out, to wrap the second cable around the entwined first cable and rope, and to unwrap the second cable from the first cable- hoist rope combination as they are recovered.

17 A method of handling a load, the method comprising the steps of: paying out 'a load-bearing rope; paying out a service cable; wrapping one of the load-bearing rope and the service cable around the other as they are being paid out; and subsequently unwrapping the service cable and the rope from one another as they are being recovered; wherein one of the rope and the cable are paid out through a bearing device.