GB2197703A - Rope tensioning - Google Patents

Abstract

An apparatus for tensioning a rope, such as a mine shaft guide rope, includes a frame (1) with two pairs of elongate members (2) interconnected by end plates (4, 6) and a link member received in the frame and having a socket (10) attached to the rope and a yoke link (20) connected to the socket and having portions provided with holes (26) and projecting between the pairs of frame members for the holes to align with holes (24) in the frame members. Two fluid actuators (30, 32) are arranged to act between the frame and the link member to put the rope under a desired tension, the link member is adjusted to align the holes (24, 26), and pins (28) are inserted into the aligned holes to fix the position of the link member. <IMAGE>

Description

Rope Tensioning This invention relates to the tensioning of ropes, and more particularly, but not exclusively, to the tensioning of guide ropes in mine shafts to provide a guidance system for conveyances.

In the past, two distinctly different methods of guide rope tensioning have been used. One method uses weights suspended from the bottom of the rope.

Although this method works well in practice, it has the disadvantage that a large space is required below the pit bottom to accommodate the weights, adding greatly to the cost of sinking a new shaft. This problem is exacerbated where a number of ropes are suspended close to one another. The weights then have to be placed below one another to prevent fouling of adjacent ropes, so the shaft has to be sunk even deeper.

The second method involves tensioning the rope by means of a screw thread. A coil spring is placed around the thread so that the compression of the spring indicates the load applied to the rope. It is necessary to measure the load to maintain the safety factor on the rope within stipulated limits.

Although the screw thread method avoids the disadvantages associated with the weight method as the thread is mounted on a platform at the top of the shaft, it does have a number of disadvantages: The load applied may be up to 20 tons making tension very hard to apply to the rope, particularly after the equipment has been in service for several years. To cope with the load, threads of 3 to 4 inches in diameter are used, giving rise to considerable thread friction. A further problem is that the springs cannot measure the load accurately, making it difficult to maintain the correct safety factor.

Furthermore visual inspection of the upper anchorage of the rope where the tensioning thread is attached is not possible as the springs are generally encased in protective covers. Even if they were not, the rope could not he adequately inspected through the spring. Visual inspection of the rope at this point is especially desirable as the upper anchorage is the most critical portion of the rope.

The present invention seeks to eliminate the abovementioned disadvantages and according to a first aspect there is provided a method of tensioning a rope comprising the steps of applying fluid pressure to fluid actuator means arranged to act on a link-member coupled to a rope end to tension the rope and securing the linkmember against movement with respect to a frame to maintain the rope at a desired tension.

The invention also resides in a rope tensioning apparatus comprising a frame, a link-member coupled to an end of a rope and arranged to be acted on by fluid actuator means to tension the rope, and means for securing the link-member to the frame at an adjusted position to maintain a desired tension in the rope.

A better understanding of the invention and its advantages may be gained from the following description of preferred embodiments of the invention given with reference to the accompanying drawings, wherein: Figure 1 is a side view of a first embodiment of the invention; Figure 2 is a side view in the direction Il-Il in Figure 1; Figure 3 is a plan view with upper coupling plates of the frame removed; Figure 4 is a side view of a second embodiment of the invention; and Figure 5 is a view corresponding to Figure 3 of the embodiment of Figure 4.

Figures 1 to 3 illustrate a rope tensioning apparatus comprising a frame 1 having four square-section upright members 2 at its corners. The members 2 are welded to a support plate 4 having a central aperture to accommodate a guide rope. A pair of coupling plates 6 are attached to the upper ends of the members 2 for rigidity of the frame. The support plate 4 is seated via a friction pad on a baseplate 8. The friction pad facilitates turning of the guide rope to minimise wear of the rope at certain points. The baseplate is itself bolted to a head frame member.

The uppermost end of the rope to be tensioned is capped with a rope socket 10. The upper end of the socket defines a channel having a pair of side walls 12, 14 each of which have a central aperture 18. A plate-like yoke-link 20 is mounted in the channel between the plates 12, 14 and coupled thereto by a retaining pin 22 passed through apertures 18 and a corresponding aperture in the yoke-link. The pin may incorporate a strain gauge.

The frame members 2 are provided with a series of regularly spaced holes 24 along their length. The yoke-link is also provided with a series of holes 26 at its sides. The yoke-link holes 26 are separated by different distances and are arranged so that one will always be in substantial registration with an overlying frame hole for all positions of the yoke-link along the frame. A fastening pin 28 is inserted through aligned frame and yoke-link holes on each side of the yokelink to secure the frame and the yoke-link to one another.

In operation a pair of hydraulic cylinders 30, 32 are arranged between opposite pairs of frame members 2 beneath the yoke-link 20. With the yoke-link coupled to the rope socket, the hydraulic cylinders are coupled together and hydraulic pressure is applied via a pump.

The cylinders bear on the underside of the yoke-link and cause the yoke-link to be elevated, so tensioning the rope. Pressure is applied to the cylinders until a required applied load is indicated by a load indicating gauge provided in the hydraulic circuit. The fastening pins 28 are then inserted through the aligned yoke-link and frame member holes. If none of the holes are exactly aligned, the cylinders are extended or relaxed slightly until the pins can be inserted. With the pins 28 in position the cylinders are relaxed so that the load is transferred to the pins 28. The cylinders may then be removed and used to tension another rope.

The above described arrangement is suitable for tensioning ropes used in shafts of depths of 500 m or greater, where the small variation in yoke-link position which may be needed to align the holes is of little significance. However in shafts of lesser depth using shorter ropes such a variation may be of great consequence. This problem may be overcome by the embodiment illustrated in Figures 4 and 5. In this embodiment the yoke-link includes a follower 34 arranged on a threaded stem 36 and a nut 38 threaded on the stem 36. Pressure is applied to the underside of the yoke-link by the hydraulic cylinders in the same way as in the previous embodiment to tension the rope until the correct load is indicated by the gauge.Then, instead of relaxing or extending the cylinders until the holes are aligned, the follower 34 is raised, nut 38 being relaxed as necessary until holes 40 in the follower are in alignment with holes on the frame member. The fastening pins may then be inserted and the nut 38 screwed down by hand to the follower and the hydraulic pressure relaxed.

The holes in the yoke-link are slightly elongated to facilitate insertion of the fastening pins. The tension in the rope may be checked at any time by placing the hydraulic cylinders in position under the yolk-link and applying hydraulic pressure. Weights 42 are attached eccentrically to the pins so that when the load is relaxed from the pins and transferred to the hydraulic cylinders the weights cause the pins to rotate indicating that the pins can be removed. The rope tension may then be determined from the reading on the load indicating gauge.

Although the invention has been described with reference to mine shaft guide ropes, it will be appreciated by the skilled reader that the method and apparatus are suitable for tensioning any long rope whether vertical or horizontal.

Claims (16)

1. A method of tensioning a rope comprising the steps nf applying fluid pressure to actuator means arranged to act between a frame and a link member coupled to a rope end, thereby to produce a desired tension in the rope, adjusting the link member without substantially changing the tension in the rope to bring securing means on the link member and frame into cooperative alignment, engaging the securing means to fix the link member against movement relative to the frame to maintain the rope substantially at said desired tension, and releasing the pressure from the actuator means.

2. A method according to claim 1, wherein the actuator means is removed from the frame and link member after releasing the pressure.

3. A method according to claim 1 or 2, wherein the link member is adjusted to bring holes in the link member and the frame into alignment, and a securing element is inserted into the aligned holes to fix the link member relative to the frame.

4. A method according to claim 3, wherein the frame has a series of holes spaced apart at a given distance, the link member has a series of holes spaced apart at a distance different to said given distance, and the link member is adjusted by varying the fluid pressure applied to the actuator means to bring closely aligned holes in the frame and link member into exact alignment.

5. A method according to claim 3, wherein the link member has a first part securely attached to the rope and on which the actuator means acts, and a second part including a hole and connected to the first part to be adjustable relative thereto, and the link member is adjusted to bring the hole in the second part into alignment with one of a series of holes in the frame by relatively adjusting said first and second parts of the link member.

6. A method of tensioning a rope substantially as herein described.

7. A rope tensioning apparatus comprising a frame, a link member coupled to a rope end and movable relative to the frame, fluid actuator means for acting between the frame and link member to produce a desired tension in the rope, and securing means for fixing the link member to the frame to maintain substantially said desired tension in the rope, said securing means comprising means on the link member and frame capable of being brought into cooperative alignment by adjusting of the link member and without substantially changing the desired tension in the rope.

8. An apparatus according to claim 7, wherein the securing means comprises holes in the link member and frame and a securing element insert able into aligned holes of the frame and link member.

9. An apparatus according to claim 8, wherein the frame has a series of holes spaced apart at a given distance, and the link member has a series of holes spaced apart at a different distance, whereby the holes in the frame and link member can be brought into alignment by displacement of the link member through a distance substantially less than the separation of the holes.

10. An apparatus according to claim 8, wherein the link member comprises a first part securely attached to the rope and arranged for the actuator means to act thereon, and a second part including a hole and connected to the first part to be adjustable relative thereto, and the frame has a series of holes, the first and second parts of the link member being relatively adjustable for bringing the hole in the second part to align with one of the holes in the frame without changing.the tension of the rope.

11. An apparatus according to claim 10, wherein the first and second parts of the link member are connected together by a threaded connector, and said relative adjustment is effected by rotation of said connector.

12. An apparatus according to any one of claims 7 to 11, wherein the link member comprises a pair of opposed lateral protrusions, and the actuator means comprises a pair of piston and cylinder devices for acting between the frame and the respective protrusions.

13. An apparatus according to any one of claims 7 to 12, wherein the frame comprises two pairs of elongate elements interconnected by end plates, each pair of frame elements receiving therebetween a repsective laterally projecting portion of the link member and having means for securing said portion thereto to fix the position of the link member.

14. An apparatus according to any one of claims 7 to 13, wherein the link member includes a socket fastened to the rope, and a link adapted to be fixed to the frame by the securing means, the link being coupled to the socket by a connector incorporating a strain gauge.

15. An apparatus according to claim 14, wherein the socket defines a channel receiving the link and the connector is a pin extending perpendicularly to the longitudinal axis of the rope and passing through aligned apertures in the side walls of the channel and the link.

16. A rope tensioning apparatus substantially as herein described with reference to the accompanying drawings.