WO2008100150A1

WO2008100150A1 - Winch device

Info

Publication number: WO2008100150A1
Application number: PCT/NO2008/000048
Authority: WO
Inventors: Yngvar BORØY
Original assignee: National Oilwell Norway As
Priority date: 2007-02-14
Filing date: 2008-02-08
Publication date: 2008-08-21
Also published as: NO20070817L; NO326256B1

Abstract

A winch device (1) in which a fibre rope (22) surrounds the drum (2) of the winch (1), and in which the fibre rope (22) is placed in a belt cradle (8) surrounding the drum (2).

Description

WINCH DEVICE

This invention relates to a winch for fibre ropes; more particularly, it relates to a winch in which a fibre rope surrounds the drum of the winch, the fibre rope being placed in a belt cradle surrounding the drum.

During winching operations at sea, in which heavy items of weights in the order of several hundred tonnes, for example, are placed on the sea floor, the availability of steel ropes of sufficient strengths has become restrictive to how large items can be handled. The sea floor can be several kilometres below the sea surface.

Therefore, it may be necessary to use fibre ropes in order for the largest items to be placed in deep water.

The use of fibre ropes for operations of this kind means that conditions that are not normally restrictive when steel ropes are used, have to be taken into consideration. For example, the life of a fibre rope, which includes a considerable portion of carbon fibres, depends directly on the number of flexures that the fibre rope is subjected to.

Winching operations of this kind are often heave-compensated and, therefore, the lifting rope will be reeled out and in on the winch continuously as a consequence of the heave motion of the lifting vessel. Even if the item being lifted is at rest relative to the sea floor, the lifting rope will still be reeled in and out, whereby the life of a fibre rope is reduced relatively quickly.

Fibre ropes do not possess sufficient resistance to crushing, either, for them to be reeled into multiple layers on a drum when there is full lifting force on the fibre rope.

It is known to coil a fibre rope multiple turns like a belt around two parallel drums (traction winch) before the fibre rope is pulled by a relatively small force onto a storage reel, often in multiple layers.

However, such a solution means that the fibre rope is subjected to bending every time it enters a drum and every time it leaves the drum. If the fibre rope is coiled in five parallel turns around the two drums, it will be subjected all the time to repeated bending at ten points, which reduces its life to an unacceptable degree.

From the use of steel ropes it is known to let the steel rope surround a smooth drum by multiple turns before it is fed onto a storage drum. The steel rope is moved sideways on the drum by a tilted free-running guide ring. During a revolution of the drum, the guide ring moves the steel rope sufficiently for the steel rope under reeling to be accommodated as it is fed onto the drum. Correspondingly, there is arranged, on the opposite end portion of the drum, a guide ring for moving the steel rope in the opposite direction along the drum, when the drum rotates in the opposite direction of rotation.

A fibre rope will not be able to resist the lateral displacement force which is necessary to move a number of turns sideways on the drum under full load, without being damaged. As regards the reeling of fibres onto a drum, US patent 5947406 discloses a reeling device for fibreglass, whereas US patent application 2005/019116 discloses equipment for splicing fibre ropes during lifting operations.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art .

The object is achieved in accordance with the invention through the features which are specified in the description below and in the claims that follow.

A winch in accordance with the invention, in which a fibre rope surrounds the drum of the winch, is characterized by the fibre rope being placed in a belt cradle surrounding the drum.

It is advantageous that the belt cradle is continuous as the belt cradle extends, after the fibre rope has left the belt cradle, around a reversing sheave back into the drum, where it is fed in between the entering fibre rope and the drum.

A tilted free-running guide ring moves the belt cradle together with the fibre rope in the longitudinal direction of the drum, whereby the fibre rope and the belt cradle can be fed continuously onto the cylinder jacket of the drum.

The reversing sheave is, with advantage, connected to a pre- tensioning device, for example in the form of an actuator, whereby the belt cradle can be tensioned further if it should glide to an undesirable degree along its surrounding direction.

The belt cradle typically comprises an elastic material which is adapted for the fibre rope, for example fibre-reinforced rubber, and in which longitudinal reinforcement in the form of steel rope or synthetic fibres is embedded. The cross- section of the belt cradle is typically given a rounded rectangular shape with an external groove complementariIy matching the fibre rope.

The belt cradle is continuous in the sense that it constitutes a continuous belt, but it may be constructed from shorter belt portions or other components.

It is often appropriate also to use cross-reinforcement to absorb the transversal forces occurring during the movement of the belt cradle in the longitudinal direction of the drum. A contact armouring may, completely or partially, form the bearing surface of the belt cradle against the drum.

The device according to the invention overcomes known weaknesses in the use of fibre ropes for heavy winching operations in a simple and reasonable manner. Known equipment for the use of steel ropes can be adapted relatively easily for the use of a fibre rope without the fibre rope being subjected to adverse strain to an unnecessary degree during operation.

In what follows, there is described an example of a preferred embodiment which is visualized in the accompanying drawings, in which:

Figure 1 shows in perspective a principle drawing of a winch which is provided with a belt cradle in accordance with the invention;

Figure 2 shows a plan view of the winch of figure 1;

Figure 3 shows a side view of the winch of figure 1; and

Figure 4 shows, on a larger scale, a cross-section of the belt cradle and a fibre rope. In the drawings, the reference numeral 1 indicates a winch, in which a cylindrical drum 2 is rotatable about a drum axis 4. The drum 2 is supportingly connected to the supporting structure 6 of the winch 1. Necessary components known per se, such as motors, attachments and connections, are not shown.

A belt cradle 8 surrounds the cylindrical drum 2 by a number of turns, the belt cradle 8 running from the drum 2 around a reversing sheave 10.

The reversing sheave 10 is connected to an actuator 12 which is arranged to tighten the belt cradle 8 by the desired force. In this preferred embodiment, the belt cradle 8 runs over a first guide sheave 14 and a second guide sheave 16, respectively.

The reversing sheave 10, actuator 12 and guide sheaves 14, 16 are connected to the supporting structure 6 by means of said attachments, not shown.

The drum 2 is provided with two tilted, freely rotating guides 18 of an embodiment known per se, see figure 3. The guides 18 are supported in stationary guide attachments 20 which are connected to the supporting structure 6.

As the belt cradle 8 is fed onto the drum 2 from the reversing sheave 10, the belt cradle 8 abuts one of the guides 18. Thereby, the belt cradle 8 is moved axially on the drum 2, moving also the adjacent other belt cradle turns surrounding the drum 2 correspondingly.

The inclination of the guide 18 is chosen to be such that the belt cradle 8 is moved by a belt-cradle width in a turn of the drum 2. A fibre rope 22 is placed in a groove 24 in the belt cradle 8.

In this preferred exemplary embodiment the fibre rope 22 extends from a load, not shown, and is placed into the belt cradle 8 at a reel-on point 26, at which the fibre rope 22 abuts the belt cradle 8 which is reeled onto the drum 2 from the reversing sheave 10 via the guide sheave 14.

The fibre rope 22 lies in the belt cradle 8 while the belt cradle 8 rotates with the drum 2, the belt cradle 8 being moved axially along the drum 2 at the same time, as it has been explained above.

The fibre rope 22 leaves the belt cradle 8 before the belt cradle 8 is reeled over the other guide sheave 16 on its way to the reversing sheave 10.

By an opposite direction of rotation, the belt cradle 8 and fibre rope 22 run in a corresponding manner in the opposite direction.

Thus, the fibre rope 22 is not subjected to flexures while in the belt cradle 8. When compensating for heave movements the fibre rope 22 will be subjected to flexures only as it is fed into and out of the belt cradle 8.

In figure 4 the belt cradle 8 is shown in an embodiment in which the belt cradle 8 comprises an elastic material 28 which is provided with longitudinal reinforcement 30. The belt cradle 8 is further provided with a contact armouring 32 arranged to bear on the drum 2.

Claims

C l a i m s

1. A winch device (1) in which a fibre rope (22) surrounds the drum (2) of the winch (1) , c h a r a c t e r i z e d i n that the fibre rope (22) is placed in a belt cradle (8) surrounding the drum (2) .

2. The device in accordance with claim 1, c h a r a c t e r i z e d i n that the belt cradle (8) runs around a reversing sheave (10) .

3. The device in accordance with claim 1, c h a r a c - t e r i z e d i n that the belt cradle (8) is axialIy movable on the drum (2) .

4. The device in accordance with claim 1, c h a r a c t e r i z e d i n that a guide (18) disposed at an angle relative to the centre axis (4) of the drum (2) is arranged to hit the belt cradle (8) in order, thereby, to move the belt cradle (8) axially on the drum (2) as the belt cradle (8) is being reeled onto the drum (2) .

5. The device in accordance with claim 1, c h a r a c - t e r i z e d i n that in cross-section the belt cradle (8) is given a rounded rectangular shape with an external groove (24) complementarily matching the fibre rope (22) .

6. The device in according to claim 1, c h a r a c - t e r i z e d i n that the belt cradle (8) which comprises an elastic material (28) is provided with at least one longitudinal reinforcement (30) . The device in accordance with claim 1, c h a r a c t e r i z e d i n that the belt cradle (8) includes a contact armouring (32) .