WO2008044996A1

WO2008044996A1 - Wire attachment on a drill rig

Info

Publication number: WO2008044996A1
Application number: PCT/SE2007/050736
Authority: WO
Inventors: René DEUTSCH; Peter Gunnarsson
Original assignee: Atlas Copco Rock Drills AB
Current assignee: Epiroc Rock Drills AB
Priority date: 2006-10-13
Filing date: 2007-10-12
Publication date: 2008-04-17
Anticipated expiration: 2009-04-13
Also published as: SE530439C2; SE0602154L

Abstract

The invention relates to an adjustable fixing device (9A, 9B) for a wire rope (8A, 8B) at a drill rig (1), which wire rope (8A, 8B) is arranged to drive a rock drilling machine (5) to and fro along a feed beam (4), both ends of the wire rope (8A, 8B) being fixed in separate fixing devices, wherein at least one of the ends of the wire rope (8A, 8B) is fixed in an adjustable fixing device (9A, 9B) that includes a tightening means (14A) for tightening the wire rope (8A, 8B) and fix it axially, and a rotational block (12, 15A-C) for preventing the wire rope (8A, 8B) from ro- tation at the adjustable fixing device (9A, 9B). The invention also relates to a drill rig including such a fixing device, and to the use of a rotational block at the fixing device of a wire rope at a drill rig.

Description

FIXING DEVICE FOR A WIRE ROPE ON A DRILL RIG

Technical field of the invention

The present invention relates to a wire rope fixing device according to the preamble of claim 1. The invention also relates to a drill rig including such a wire rope fixing device, and to the use of a rotation block at said fixing device.

Background of the invention and prior art

Two of the most important features of a drill rig is its endurance and reliability. All parts of the equipment need to answer to the high demands that are required in the extreme working operations of a drill rig. It is also important that its accuracy can be withheld under these conditions.

Generally (see fig. 1), a rock drill rig comprises a movable carrier 1, a boom 2 and a feed beam 4 connected to the boom 2 via e.g. a feed beam holder 3. The feed beam 4 and the feed beam holder 3 are movable in relation to each other along at least part of the length of the feed beam, thereby permitting relative movement between them. A drilling machine 5 is movably arranged on the feed beam 4 and may be moved between the drill end 41 and the rear and of the feed beam for affecting the drill string 10. The drilling machine may normally be moved by means of an arrangement including one or several wire ropes that are driven around sheaves by a hydraulic cylinder.

A problem concerning driving means that include wire ropes is the slacking or yielding of wire ropes, which implies that the wire ropes need to be tightened every now and then, whereby it may be necessary to interrupt operation from time to time. Even at small extensions of the wire ropes the movement of the drilling machine becomes irregular and the bigger the deviation, the bigger the risk that a wire rope slips out of its track at one of the sheaves, in which case the drilling operation needs to be aborted. Additionally, the wire rope tend to thicken as a result of its slackening, and it might even become thicker than what the sheaves are designed for, whereby the risk that slips out of a sheave is drastically increased. To solve the problems caused by the slacking of the wire ropes some sort of tightening device is normally arranged on at least one of the ends of each wire rope. A problem with known types of tightening devices, which often include a threaded pin and a number of nuts is that the wire ropes need to be tightened at regular intervals, leaving it up to the operator to make sure that the wire ropes are kept tight enough. In order to minimise the number of operational break downs the operator often tend to wait as long as possible before taking action. This may incur break downs due to the wire rope slipping out of its track, demanding a more time consuming service break down. Additionally, as the wire rope, as a function of the length of the threaded pin, only may be tightened to a certain degree it has to be replaced after a certain time of use. Traditionally, it has been considered that continuous extension of the wire rope is due to continuous slacking.

However, in recent experiments it has been noted that a wire rope after a certain initial slacking reaches a point from where it will not slack at all, or only on a very small scale. The invention is based on this knowledge, and an analysis of what causes the operational slacking and the taking of a suitable measure.

In US 6 679 480 a type of tightening device is shown, which partly corresponds to a type of conventional tightening device that is being used to tighten continuously slackening wires.

Summary of the invention

The main object of the present invention is the provision of a wire rope fixing device, in which the wire rope, after an initial slacking to a point where it has settled, only needs to be tightened very rarely or not at all, and in which the wire rope may be used for a longer period before being worn out than in a conventional fixing device. This is accomplished by features presented in the charactering portions of the independent claims. Preferred embodiments of the invention are presented in the dependent claims. According to a first aspect the invention relates to an adjustable wire rope fixing device on a drill rig, which wire rope is arranged to drive a rock drilling machine to and fro along a feed beam, both ends of the wire rope are fixed in separate fixing devices, at least one of the ends of the wire rope is fixed in an adjustable fixing device, wherein the adjustable fixing device includes a tightening means for tightening the wire rope and fix it axially, and a rotational block for preventing the wire rope from rotation at the adjustable fixing device.

According to a second aspect to the invention relates a drill rig including: a feed beam; a rock drilling machine, which is movably arranged on the feed beam; a pressure cylinder with a movable rod piston; a wire rope, which is connected to the movable piston rod and to the rock drilling machine in such a way that the movement of the piston rod controls the movement of the rock drilling machines along the feed beam, the ends of the wire rope being fixed in separate fixing devices, wherein at least one of the ends of the wire rope is fixed in an adjustable fixing device. Further, the adjustable fixing device include a tightening means for tightening the wire rope and fix it axially, and a rotational block for preventing the wire rope from rotation at the adjustable fixing device.

According to a third aspect, the invention relates to the use of a clamp connection for preventing that a threaded pin attached to the end of a wire rope on a rock drilling machine rotates at its fixing device, the clamp connection is arranged to act radially towards the threaded pin such that it is radially fixed with respect to the threaded pin, a support is arranged adjacent the clamp connection, which support prevents the clamp connection and hence the threaded pin from rotation.

The invention according to the aspects cited above solves problem that appear at prior art fixing devices. These and other aspects and advantages of the invention will be apparent from the detailed description and the accompanying drawings. Short description of the drawings

In the detailed description of the present invention reference is made to the ac^¬ companying drawings, of which:

Fig. 1 shows a schematic view of a drill rig according to the invention;

Fig. 2 shows a schematic view of a feed beam with a drilling machine that is controlled by a pressure cylinder in accordance with the invention;

Fig. 3 shows a first adjustable wire rope fixing device according to the invention;

Fig. 4 shows a second adjustable wire rope fixing device according to the invention;

Fig. 5 shows an exemplifying clamp connection for use at the wire rope fixing devices figures 3 and 4;

Fig. 6 shows a schematic view of an adjustable fixing device according to prior art;

Fig. 7 shows a schematic view of an adjustable fixing device according to the invention;

Fig. 8 shows a schematic view of an adjustable fixing device according to a second embodiment of the invention;

Fig. 9 shows a cross sectional view along section 9-9 in figur 8.

Detailed description

As is briefly explained above fig. 1 a shows schematic view of a drill rig including a movable carrier 1 , a boom 2 and a feed beam 4 connected to the boom 2 via a feed beam holder 3. The feed beam 4 and the feed beam holder 3 are movable with respect to each other in at least a part of the length of the feed beam 4. A drilling machine 5 is movably arranged on the feed beam 4 and is movable along the feed beam 4 for affecting the drill string 10. The drill string 10 includes a borecrown and interconnected rods (not shown).

From fig. 1 and 2 it is apparent that the feed beam 4 has a drill end 41 from which the borecrown extends during drilling operation and a rear end 42 opposite the drill end 41. From figure 2 it is apparent that a pressure cylinder 6 is arranged inside the feed beam 4. The pressure cylinder 6 is arranged to by means of a piston rod 7 drive the drilling machine 5 to and fro along the feed beam via two wire ropes 8A and 8B. It is in practice possible to utilize only one wire rope that is fixed to the drilling machine 5 halfway between its ends, but it is however for a number of reasons advantageous to utilize two wire ropes 8A and 8B, which are fixed on opposite sides of the drilling machine 5. Usually, these lines are called pull line and return line, respectively, depending on the momen- taneous direction of forces in the lines. The number of wire ropes does however not affect the general arrangement of the invention except for the fixing arrangement at the fixing points of the wire rope or wires to the drilling machine 5. In the preferred embodiment, two wire ropes are utilized which both are fixed to the drilling machine by means of loops and grummets (visas ej). The fixation to the drilling machine is however not important for the invention except for the fact that rotation of the wire ropes should not be allowed at them. Numerous solutions are however known to the skilled person. Instead, what is important for the invention is how the opposite ends of the wire ropes 8A and 8B are fixed. This is therefore described in detail below.

Sheaves 1 IA-D for low friction running of the wire ropes 8A and 8B are arranged both at opposite ends 41 and 42 of the feed beam and inside it. Preferably the sheaves 1 IA-D include an inner bearing providing low friction against the corresponding shafts. The pressure cylinder 6 may be of any conventional type and include a piston rod 7 that is arranged to glide inside the pressure cylinder 6 under influence of a hydraulic fluid. The pressure cylinder 6 has an outer end 62, which is fixedly arranged at the rear end 42 of the feed beam 4, and an inner end 61, which is fixedly arranged at the centre of the feed beam 4, from which the piston rod 7 extends. When the piston rod 7 is pressed outwardly towards the drill end 41 of the feed beam 4 (movement A) the drilling machine 5 will be moved towards the rear end 42 and when the piston rod 7 is retracted into the pressure cylinder (movement B) the drilling machine 5 will be moved towards the drill end 41 of the feed beam 4. In accordance with the arrangement of wire ropes 8A-B and sheaves 1 IA-D of the shown embodiment, any movement of the piston rod 7 and the sheaves 11C and 1 ID attached to its outer end, will yield double the movement of the drilling machine 5, which is illustrated in figure 2 by the movement arrows 2xA and 2xB of double magnitude at the drilling machine 5. The invention may also come in handy in other types of arrangements for wire ropes and pressure cylinders.

As mentioned above the invention mainly relates to the fixing devices 9A and 9B for wire ropes that are fixedly arranged at the feed beam 4 and not those that are arranged on the drilling machine 5. In order to maintain the precision in the feeding, such that the carriage and the drilling machine 5 respond directly in both directions to the smallest movement of the piston rod 7 of the pressure cylinder 6 via the wire ropes 8A and 8B, it is important that the fixing devices do not slack off. As the wire ropes 8A and 8B tend to slack a little bit after installation it is desirable that it would be possible to tighten them at the fixing devices 9A and 9B.

Figure 3 illustrates a first embodiment of the wire rope fixing device 9A according to the invention. A threaded pin 13 is clamped onto the end of the wire rope 8A. The threaded pin is inserted through an unthreaded bore (not shown) in the wire rope fixing device 9 A and is retained by two nuts 14A and 14B. The nut closest to the wire rope fixing device 9A is a tightening nut 14A used for tightening the wire rope. The tightening nut 14A is preferably locked by means of a locking nut 14B, which is screwed into tight connection with the tightening nut once this has been screwed into a position that provides the desired tension in the wire rope 8A. The locking nut 14B is not necessary, instead it functions as a safety arrangement to minimise the risk that the nut is loosened. Other ways of locking the nut 14A are also known to the skilled person.

Normally, the nuts 14A and 14B are adjusted both at installation of the wire rope and after a certain time of use when the wire rope has "yielded" and slackened somewhat. A part from this the wire ropes will not require tightening due to the fixing device according to the invention, which is a clear advantage with respect to known devices in which the wire ropes have had to be tightened continuously throughout their operational lifetime, e.g. until the entire tightening extent of the threaded pins was consumed, at which point the wire ropes were discarded and replaced by new ones. With the fixing device according to the invention the number of operational breakdowns may be vastly reduced, both since the wire rope does not need to be tightened as often as before, because the tighter tension that is guaranteed and reduces the number of failures, such as e.g. the wire rope falling out of engagement with the sheaves, but also because the wire rope does not need to be replaced unless it has been damaged.

The idea of the invention comes from that it in experiments has been shown that the wire rope, after an initial slackening, normally should not slacken anymore and that the slackening or yielding that still has appeared at conventional fixing devices mainly is due to rotation of the wire rope and not as assumed in prior art that the wires are being stretched. As known, a wire rope consists of twisted steel wires, and due to the forces that arise during normal operation at the drill rig, the wire rope is somewhat rotated, wherein it is both extended and widened and wherein the problems mentioned in the background part arise. Thus, the invention is based on the knowledge that it is the rotation at the ends of the wire rope that is the cause of the continuous slackening. Hence, the problem of the continuously slackening wire rope is solved by preventing the ends of the wire rope from rotation. The ends of the wire rope that are fixed to the drilling machine have, as is mentioned above, conventionally been configured in loops and fixed such that they will not rotate. Hence, the problems arising from slackening of the wire rope may be avoided by making sure that also the adjustable fixing devices at the drill rig 1 are arranged such that the ends of the wire rope will be prevented from rotation in these as well.

This is achieved in accordance with the invention by means of a rotational block 12 (see especially figure 5), which in the shown embodiments consists of a clamp connection including an upper and a lower half 12A and 12B, respectively, which are pressed towards each other by means of screws 17 that interact with threads in the holes of the lower half 12B of the clamp connection 12. Both halves 12A and 12B, have a semicircular recess that form an opening 18, in which the threaded pin 13, is adapted to be held. In order to achieve the best possible locking against the threaded pin 13, the inside of the recess opening 18 is provided with threads that correspond to the threads on the outside of the threaded pins 13. By means of the rotational block 12 according to the shown embodiment of the invention the clamping force is applied radially towards the threaded pin 13, without risking to damage the thread.

In the schematic figures 6 and 7 the principle of the invention is shown as a comparison between a known solution in figure 6 and the solution according to the invention in figure 7. An axial pulling force F_A acts on the wire rope with a varying magnitude throughout operation. Given that the wire rope 8 is twisted, part of the pulling force F_A will be transformed into a torque T, which is transmitted to the threaded pin 13. In the conventional fixing device 9' (shown in figure 6) nothing other than nuts 14A-B and 2 IA-B, respectively, are arranged on either side of the bore 20 in the fixing device 9'. The nuts are adapted to absorb axial forces FA i and F_A2, respectively and thereby fix the threaded pin axially. However, it appears that the threaded pin 13 has not been totally prevented from rotation in this type of fixing device. In short, there is nothing in the conventional fixing device 9' that sufficiently counteracts the torque T and prevents the threaded pin from rotation. In figure 7 the rotational block 12 is schematically illustrated in form of two radial arrows of force F_R that correspond to any kind of clamp connection that acts radially towards the threaded pin 13. The clamp connection is arranged by means of a radial force against the threaded pin such that it is prevented from rotation with respect to the threaded pin 13. Further, a support (not shown in fig. 7) is arranged in order to make sure that the rotational block does not rotate. The support suitably consists of a detail which fits tightly with respect to the rotational block and preferably the support is integral with a part of the solid structure at or close to the fixing device 9.

In the embodiment in figure 3 a rotational block is prevented from rotation by means of two side sheets 15A and 15B which are natural parts of a block 20 at the feed beam 4 on which an outer sheave 1 IA is fixed. The solution that is shown in figure 3 is thus adapted to the existing structure of the feed beam and its appurtenances. The adaptation mainly consists in that the width of the tightly fitting rotational blocks correspond to the distance between the already existing side sheets 15A and 15B, such that it thereby is prevented from rotation.

In figure 4 it is shown how the second wire rope 8B may be fixed at the second wire rope fixing device 9B. Similar to the first fixing device a threaded pin 13 is attached to the wire rope 8B. Further, the threaded pin is inserted through a bore 20 (see figure 7) in a centre block 16 that retains the pressure cylinder 6 inside the feed beam 4. A tightening nut 14A and a locking nut 14B are screwed onto the projected part of the threaded pin on the farther side of the centre block 16. Just as in the embodiment of figure 3 the nuts 14A and 14B do not guarantee that the threaded pin 13 will not rotate. Thus, a rotational block 12 is arranged on this threaded pin 13 too. At the centre block there is however no natural part of the structure that prevents the rotational block from rotation. Hence, in the shown embodiment, a locking sheet 15C is screwed onto the centre block, efficiently keeping the rotational block 12 and the threaded pin 13 from rotation. An alternative to arranging a locking sheet could be to mill off a recess in the centre block 16, which recess should be adapted to receive a rotational block 12 tightly inside it and prevent it from rotation. Such a milling may even be both cheaper and more efficient than the embodiment with the locking sheet 15 C, which is shown in figure 4.

Yet another alternative embodiment for preventing rotation of the wire rope at its fixing device is schematically shown in figures 8 and 9 and consists in designing the threaded pin 13 and the bore 20 such that they are locked from mutual radial movement. In the embodiment shown in these figures a longitudinal recess 23 is arranged in the threaded pin 13 and another longitudinal recess 24 is arranged in the bore, wherein a bar 22 is arranged in the space that arises from the two longitudinal recesses 23 and 24. In such an embodiment the rotational block according to the invention is provided by the mating of the bore 20 and the threaded pin 13. Other, similar embodiments are of course feasible, a limitation is however that the threaded pin should have a substantially circular outer cross section free from bulges, as it should be possible to provide it with nuts, such as the nuts 14A and 14B.

The invention is however not limited to any of the embodiments that are described or shown in this application. Namely, the wire rope fixing device according to the invention is intended to be adapted to the existing structure at which it is to be implemented. Thus, the invention is only limited by the claims below.

Claims

Claim

1. Adjustable fixing device (9A, 9B, 9, 9") for a wire rope (8A, 8B) at a drill rig (1), which wire rope (8A, 8B) is adapted to drive a rock drilling machine (5) to and fro along a feed beam (4), both ends of the wire rope (8A, 8B) being fixed in separate fixing devices, wherein at least one of the ends of the wire rope (8A, 8B) is fixed in an adjustable fixing device (9A, 9B, 9, 9"), characterised in that the adjustable fixing device (9A, 9B, 9, 9") includes a tightening means (14A) for tightening the wire rope (8A, 8B) and fix it axially, and a rotational block (12, 22) for preventing the wire rope (8A, 8B) from rotation at the adjustable fixing device (9A, 9B, 9, 9").

2. Adjustable fixing device (9 A, 9B, 9) for a wire rope according to claim 1, characterised in a threaded pin (13) with external threads, which pin is fixed on the end of the wire rope (8A, 8B), the rotational block (12) consisting of a clamp connection with internal threads that mate with the external threads on the threaded pin (13), the clamp connection being adapted to be clamped onto the threaded pin (13) such that the clamp connection and the threaded pin (13) may not rotate with respect to each other, preferably without damaging the threads of the threaded pins (13).

3. Adjustable fixing device (9A, 9B) according to claim 2, characterised in that a support (15A-C) is arranged to fix the clamp connection (12) radially, such that it is prevented from rotation.

4. Adjustable fixing device (9A, 9B, 9") according to any of the precedent claims, characterised in that the tightening means (14A) consists of a tightening nut and that a locking means (14B) in form of a locking nut is arranged to lock the tightening means in the desired position.

5. Drill rig (1), including: a feed beam (4); a rock drilling machine (5), which is movably arranged on the feed beam

(4); a pressure cylinder (6) with a movable piston rod (7); a wire rope (8A, 8B), which is connected to the movable piston rod and to the rock the drilling machine (5) such that the movement of the piston rod (7) controls the movement of the rock drilling machine (5) along the feed beam, the ends of the wire rope (8A, 8B) being fixed in separate fixing devices, wherein at least one of the ends of the wire rope (8A, 8B) is fixed in an adjustable fixing device (9A, 9B, 9, 9"), characterised in that the adjustable fixing device (9A, 9B, 9") includes a tightening means (14A) for tightening the wire rope (8A, 8B) and fix it axially, and a rotational block (12, 22) for preventing the wire rope (8A, 8B) from rotation at the adjustable fixing device (9A, 9B, 9, 9").

6. Drill rig (1) according to claim 5, characterised in that it includes two wire ropes (8A, 8B), one end of both the wire ropes (8A, 8B), respectively, being looped and fixed to the rock drilling machine.

7. Drill rig (1) according to claim 5 or 6, characterised in that the end of the tightening means (14A) that is arranged on that part of the threaded pin (13) that has been inserted into the bore (20), for preventing axial movement of the threaded pin back and forth through the bore (20) and for keeping the wire rope (8A, 8B) stretched.

8. Drill rig (1) according to claim 7, characterised in that the rotational block (12) consists of a clamp connection with internal threads that correspond to external threads on the threaded pin (13), the clamp connection being adapted to be clamped onto the threaded pin (13) such that the clamp connection and the threaded pin (13) may not rotate with respect to each other, preferably without damaging the threads of the threaded pins (13).

9. Drill rig (1) according to claim 7, characterised in that the bore (20) at the fixing device (9") has a non circular cross section, the threaded pin (13) hav- ing a cross section that mates the cross section of the bore (20), such that the threaded pin is prevented from rotation inside the bore (20).

10. Drill rig (1) according to claim 9, characterised in that the threaded pin (13) has a longitudinal recess (23) and that the bore (20) has a corresponding longitudinal bulge, which lock the threaded pin (13) and the bore (20) against mutual radial movement.

11. Drill rig (1) according to claim 9, characterised in that the threaded pin (13) has a longitudinal recess (23) and that the bore (20) has a a corresponding longitudinal recess (24), the rotational block (22) consisting of a bar adapted to be arranged and fit tightly in the space that arises from the two recesses (23, 24), such that the bar (22) locks the threaded pin (13) and the bore (20) against mutual radial movement.

12. Use of a rotational block (12, 22) for preventing that a threaded pin (13) that is fixed to the end of a wire rope (8A, 8B) at a rock drilling machine (5) rotates at its fixing device (9A, 9B, 9, 9"), characterised in that a rotational block (12, 22) is arranged, such that it also fixes the threaded pin (13) radially with respect to the fixing device.

13. Use of a rotational block (12) according to claim 12, characterised in that the rotational block (12) consists of a clamp connection (12), which is arranged with a radially acting force towards the threaded pin (13), a support (15A-C) being arranged against the clamp connection (12), which support (15A- C) prevents the clamp connection (12) and hence the threaded pin from rotation.

14. Use of a rotational block (12) according to claim 12, characterised in that the threaded pin (13) is arranged in a bore (20), the threaded pin (13) having a longitudinal recess (23) and the bore (20) having a corresponding longitudinal recess (24), the rotational block consisting of a bar (22) that is intended to be arranged and fit tightly in the space that arises from the two recesses (23, 24), such that the bar (22) locks the threaded pin (13) and the bore (20) against mutual radial movement.