GB2268154A

GB2268154A - Method of producing a rope or cable laid wire rope sling

Info

Publication number: GB2268154A
Application number: GB9213508A
Authority: GB
Inventors: Michael Lew
Original assignee: Franklin Offshore Supply & Eng
Current assignee: Franklin Offshore Supply & Eng
Priority date: 1992-06-25
Filing date: 1992-06-25
Publication date: 1994-01-05
Anticipated expiration: 2012-06-25
Also published as: GB2268154B; GB9213508D0

Abstract

An apparatus for producing rope or cable laid wire rope in the form of an endless sling comprises a rotatable platform, a sheave mounted above the platform and a sheave mounted below the platform, a further sheave provided at floor level adjacent to the platform and moveable towards and away from the platform and a flexible former wound around the sheaves and passing through the platform. The platform, carrying a rope supply, is rotated about the former to wind rope about the former to form an endless sling of twisted rope.

Description

METHOD OF PRODUCING A ROPE OR CABLE LAID WIRE ROPE GROMMET This invention relates to the production of wire rope grommets and, more particularly, to the production of cable laid grommets or grommet slings comprising of a single length of unit rope laid up in construction six times over one.

Grommet is an endless rope made up from a strand or, in the case of a cable laid grommet, from a single unit rope. A former is provided over which the rope is laid. The former may be made of a solid steel bar up to about 1/2" diameter.

For larger diameters, light weight gauge conduit tubing or any other suitable means may be used preferably in sections. The former has two main functions. Firstly, it provides a temporary centre or core over which the rope or grommet can be formed, and furthermore, the circumference can be very accurately determined, hence both the length and the matching of grommets are strictly controlled.

A unit of rope is laid over the former to a specific pitch.

The same unit rope is then wound over the former following the path of the first pith or layer. This is continued until a 6 strand rope is formed. Once the grommet is formed to the stage with a tail of unit rope remaining-the former is removed and at the same time the tail is run into the core in the known manner. The tails of the rope butt opposite to the cross-over point. The two eyes of the grommet are seized-in ensuring that the butt and the cross-over point are lost under the seizings as in the known manner.

Such grommets are used mainly as slings for the lifting of heavy loads, particularly in the off-shore industry, with diameters normally ranging between 4" in diameter and 15gut in diameter.

It is an object of the present invention to provide an improved means whereby grommets but more particularly cable laid grommets in the above diameter range and above can be produced accurately and without twist in the rope by mechanical means.

According to one aspect of the present invention there is provided an apparatus for producing rope or cable laid wire rope in the form of a grommet comprising a rotatable platform, a sheave mounted above the platform and a sheave mounted below the platform, a further sheave being provided at floor level adjacent to the platform and moveable towards and away from the platform and a former wound around the sheaves and around which rope is wound to produce cable laid wire rope grommets.

According to a further aspect of the present invention there is provided a method of producing cable laid wire rope grommets comprising the steps of winding a former around a plurality of sheaves, providing a rotatable platform between the sheaves, passing rope through the platform, and rotating the platform in order to wind the rope around the former to produce cable laid wire rope grommets.

One embodiment of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a schematic view of an apparatus for producing cable laid wire rope grommets according to one aspect of the present invention; Figure 2a is a schematic view of a sheave of the apparatus of Figure 1; Figure 2b is a schematic view of a further sheave of the apparatus of Figure 1; Figure 3 is a plan view of a rotatable turn-table of the apparatus of Figure 1; Figure 4 is a schematic view of a bobbin stand of the apparatus of Figure 1 Figure 5 is a schematic side view of a return sheave of the apparatus of Figure 1, and Figure 6 is a schematic view of a frame member of the apparatus of Figure 1.

Turning now to the Figures there is shown an apparatus for producing cable laid wire rope grommets comprising a rotating platform 1 which is set into a suitable steel housing in a pit 2 in the floor 3 of a building or factory.

The platform 1 is provided with a key-hole slot 4 as shown in Figure 3 which allows for removal of a finished grommet from the platform. The platform 1 is driven by a hydraulic power unit 5 mounted on the platform adjacent the slot 4. The hydraulic power unit 5 doubles as a balance weight for a rotating unit rope take-up stand 6 which is also mounted on the rotatable platform 1 opposite to the hydraulic power unit 5.

A sheave C is located in the pit 2 beneath the rotating platform 1. The pit sheave C is aligned with an upper sheave B which is mounted above the rotating platform 1.

The rotating unit rope take up stand 6 is mounted on the platform 1 and is rotated by a gear housing 7 fixed to the rotating platform 1. A spur wheel drive (not shown) is mounted on a drive from a hydraulic motor outwith the rotating platform 1. A bobbin (not shown) is mounted on the stand 6 and the spur gearing may be speed adjustable to keep the bobbin in a planetary motion or may be adjusted to impart positive or negative torque to the rope thus insuring a twist free finished grommet.

A frame 8 is provided over the rotating unit rope take up stand 6 which acts as a guide member to guide rope from the bobbin of the take up stand 6 over a cross-bar 9 of the frame 8 and over a return sheave 10 described below. The rope is then passed through guide means 11 mounted on the end of a hydraulic ram 12 (see Figure 5) which acts as an adjustable twisting point means before the rope is passed around the former.

The return sheave 10 is mounted at floor level on a pedestal bearing 13 which is itself mounted on adjustable guide rails 14 which allows the sheave 10 to be moved towards and away from the rotatable platform 1 to any fixed position in order to determine the length or circumference of the former F which, in turn, determines the circumferential length of the grommet. Means may be provided to apply tension to the former F as desired.

Referring now to the method used to manufacture grommets using the above apparatus, tails a and b are accommodated on the bobbin while being run into the centre of the grommet to form the core. A hydraulic motor turns the bobbin for winding on purposes while a second motor rotates the unit to control torque if required.

A rope guide is provided to act as a twist plate and for maximum flexibility comprises two hydraulic cylinders and rams with suitable guide roller attachments. Figure 2a shows the position of the sheave C in the pit 2 relative to the central orifice of the slot 4 in the rotating platform 1. Figure 2b shows the upper fixed sheave B which is on the same centre line as the lower pit sheave C.

The method of manufacturing the cable laid wire rope grommet will now be described. The length and diameter of the former is decided and is then reeled-through the system over and around the sheaves 10, B and C. Both ends of the former are then connected together. Sheave A is then laterally adjusted to apply tension to the former. Preferably the former should be in suitable length sections to facilitate removal of the former from the cable laid grommet during the insertion of the core.

A predetermined length of unit rope on a bobbin is then loaded into the rotating take-up stand 6 provided. The starting end of the unit rope is then led up over the cross bar 9 above the reel across to the deflection sheave and then to the twisting device provided by the hydraulic rams 12. This end of the unit rope is then fixed to the former by seizing wire or similar means.

Suitable tension is then applied to the unit rope by a braking device on the bobbin. A hauling rope is then attached to the former at maximum distance from sheave A. This rope is accommodated on a powered winch. In the further development A may provide the traction force power driven.

The hydraulic power unit 5 is then brought into use to revolve the whole platform assembly and operate the winch at a synchronised speed thus the unit rope wraps itself around the former at a predetermined pitch or helix angle.

The internal spur gear attached to the unit rope reel stand ensures a planetary motion. However the hydraulic power source on the platform 1 allows the operator means to control any build up of torque by increasing or retarding the degree of rotation.

When the rope handling clamp has reached its limit at sheave A it is then re-clamped at its original position and this procedure continues until the unit rope has completed one complete round of the former. A power operated sheave A would dispense with this but the time saved would be minimal.

On the second, third, fourth, fifth and sixth cycles the operator, by using the hydraulic ram guide or twist plate, is able to control the position of the unit rope in each layer or cycle so that adjacent unit ropes are maintained close together in order to ensure that the sixth and final layer falls into place.

Once the unit rope has completed six cycles and the cable laid grommet is formed it is then necessary to carry on for a further length of 1/2 the length or circumference of the grommet in order to provide tail A. This is carried out by un-laying the starting end of the unit rope by 1/2 the circumference at the same time laying in an equal amount of unit rope from the reel ie six and a half cycles. The amount of unit rope now remaining should be slightly more that 1/2 circumference to form tail B as in the known manner.

The point where the two unit ropes cross is called the tucking point and it is at this point that they have to be induced into the centre as a core thus replacing the former. The end of tail A is now fixed to the slave bobbin and wound on. Tail B remains on the pay off strand reel for convenience.

A joint in the former is removed and one free end is slipped out. By using known procedures a spike is placed between the unit ropes in such a position and held by the operator that when the cycle begins again the former is levered out of position while at the same time the unit rope is forced in to replace it. As the former is in sections it is dismantled, removed from the grommet and laid aside until the whole of tail A is in position in the centre of the cable laid rope grommet.

This is repeated for tail B but as it has to be laid in, the opposite direction from tail A, the travel of the unit or near completed grommet is reversed. As tail B nears the point of the end of tail A it is carefully measured and cut to a length which ensures both ends will butt comfortably together in the core of the cable laid grommet in the known manner. The grommet now completed can be removed from the cabling device.

Several advantages offered by the present invention include: A simple mechanical device for the manufacture of grommets, particularly cable laid grommets of large diameters and long lengths.

Significant time and labour savings.

Torsion free cable laid grommets are simple to produce.

There is little or no restriction on capacity.

Handling and manning levels are reduced.

Torsion in the unit rope is controlled by over or under twisting automatically during the laying-in process.

A constant pitch or helix angle of the unit rope is maintained automatically.

Claims

1. An apparatus for producing rope or cable laid wire rope in the form of a grommet comprising a rotatable platform, a sheave mounted above the platform and a sheave mounted below the platform, a further sheave being provided at floor level adjacent to the platform and moveable towards and away from the platform and a former wound around the sheaves and around which rope is wound to produce cable laid wire rope grommets.

2. An apparatus according to claim 1, wherein a rotating unit rope stand is mounted on the platform and is rotated by gear means mounted on the platform

3. An apparatus according to claim 2, wherein a bobbin is mounted on the unit rope stand.

4. An apparatus according to claim 2 or 3, wherein a frame is mounted over the rotating unit rope stand and guide means are provided on the frame to guide the rope onto the further sheave.

5. An apparatus according to claim 4, wherein the guide means for the rope are mounted on a hydraulic ram and further comprises a twisting device for twisting the rope upon winding onto the former.

6. An apparatus according to any one of claims 3-5, wherein a braking device is provided on the bobbin to apply suitable tension to the unit rope;

7. An apparatus according to any one of the preceding claims, wherein the platform is mounted within a steel housing below floor level.

8. An apparatus according to any one of the preceding claims, wherein the platform is provided with a key-hole slot thereby allowing removal of the finished grommet from the apparatus.

9. An apparatus according to claim 8, wherein the platform is driven by a hydraulic power unit.

10. An apparatus according to claim 9, wherein the power unit is mounted on the rotating platform adjacent the slot.

11. An apparatus according to claim 10, wherein the power unit provides a counter balance for the rotating stand.

12. An apparatus according to any one of the preceding claims, wherein the further sheave is mounted on adjustable guide rails.

13. An apparatus according to any one of the preceding claims, wherein the former comprises a plurality of sections which may be disconnected to facilitate removal of the grommet from the former.

14. An apparatus for producing rope or cable laid wire rope in the form of a grommet substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

15. A method of producing cable laid wire rope grommets comprising the steps of winding a former around a plurality of sheaves, providing a rotatable platform between the sheaves, passing rope through the platform, and rotating the platform in order to wind the rope around the former to produce cable laid wire rope grommets.

16. A method of producing cable laid wire rope grommets according to claim 15, wherein the platform is driven by a motor mounted thereon.

17. A method of producing cable laid wire rope grommets according to claim 15 or 16, wherein the first sheave is laterally adjusted to apply tension to the former.

18. A method of producing cable laid wire rope grommets substantially as hereinbefore described.