WO2012098492A2

WO2012098492A2 - Drill rig

Info

Publication number: WO2012098492A2
Application number: PCT/IB2012/050210
Authority: WO
Inventors: Jason Paul VRDOLJAK
Original assignee: Stratabolt (Proprietary) Limited
Priority date: 2011-01-17
Filing date: 2012-01-17
Publication date: 2012-07-26
Also published as: GB201100704D0; WO2012098492A3; ZA201305457B

Abstract

The invention concerns a drill rig 10, 70, 100 which includes an extendable thrust cylinder 14 and an extendable clamping cylinder 12. The clamping cylinder 12 is used for clamping the drill rig between a floor and hanging wall of a mine working. To ensure that the drill rig is compact, the clamping cylinder 12 is mounted inside the thrust cylinder 14. The drill rig further includes a drill carriage 24 which is slidably connected with respect to the thrust cylinder 14 and moveable in a carriage movement direction substantially parallel to the axes of extension and contraction of the cylinders 12, 14. The carriage 24 is configured to carry a drill in use. A flexible, mechanical coupling 26 is provided between the drill carriage 24 and the thrust cylinder 14 so that extension and contraction of the thrust cylinder causes the drill carriage to move in the drill carriage movement direction. The mechanical coupling 26 is configured to provide an amplitude advantage so that the distance of travel of the drill carriage 24, and hence of a drill carried by the drill carriage in use, is greater than the extension of the thrust cylinder 14.

Description

DRILL RIG"

BACKGROUND TO THE INVENTION

This invention relates to a drill rig. In particular, but not exclusively, this invention relates to a drill rig for use in rock bolting.

Rock bolts are commonly used in the mining industry to stabilise the rock surrounding an excavation. Installation of a rock bolt requires firstly the drilling of a hole in the rock face and secondly inserting the rock bolt in the hole. Drill rigs may be used in both stages i.e. to drill holes and to insert rock bolts therein. Equipment currently used in installing rock bolts range from handheld rock drills to powered vehicles on which multiple drilling machines are mounted.

Excavations with low working heights pose a particular challenge to the installation of rock bolts in a hanging wall of a mine working, especially if the rock hardness is such that percussion drilling is required. Percussion drilling equipment is generally heavy and bulky, thus making drilling in low working height conditions difficult. This is a situation common for example in gold and platinum mines in Southern Africa where working heights are usually less than 2m, most commonly less than 1.5m, and rock compressive strength is usually over 120MPa.

A number of different drill rigs which are compact enough to be used in low working height conditions have been proposed. One such drill rig is described in the specification of South African patent 2001/10382. The drill rig of ZA2001/10382 includes two spaced apart telescopic clamping cylinders and a carriage which is located between the cylinders and movable along them. The rig further includes a drill mounted on the carriage so that it is movable with the carriage. A disadvantage of this drill rig is that it still is heavy and bulky when using it in low working height environments due to the configuration of the multiple cylinders.

Single clamping cylinder drill rigs have also been proposed and these normally include one telescopic clamping cylinder mounted externally and parallel to a thrust cylinder. The clamping cylinder is used to clamp the drill rig in position while the thrust cylinder is used to drive a drill carriage and drill. A problem with these drill rigs is that the movement of the carriage and accordingly the drill mounted thereto is limited to the stroke of the thrust cylinder. Another alternative is described in the specification of international patent application PCT/IB2009/055953 which was published under WO2010/079403. This drill rig includes a single clamping cylinder and a coaxially mounted thrust cylinder. The thrust cylinder accommodates a sliding magnet which can be driven up and down by fluid pressure. Through a magnetic force coupling a carriage on which a drill is mounted is moved up and down the exterior surface of the thrust cylinder. Again a major disadvantage of this drill rig is that the movement of the drill is limited to the stroke of the thrust cylinder.

Another known drill rig is described in the specification of US6, 105,684. This drill rig is an example of one where the clamping cylinder is mounted externally and parallel to the thrust cylinder. However, this drill rig provides for an amplitude advantage on the movement of the drill rig on which the drill is mounted so that the drill moves twice the distance of the thrust cylinder's extension. This is achieved by means of a chain running over two sets of pulleys provided above and below the drill carriage respectively. A disadvantage associated with this drill rig is that it is bulky as a result of the thrust and clamp cylinders being mounted side by side. In order to stabilise the drill rig it also includes a large number of cylindrical slides, which not only makes the rig bulky but also complex. This drill rig is a massive construction and not ideally suited to be used in low working height conditions.

Another drill rig that makes use of a chain drive to move a drill carriage is described in the specification of US2007/0286707. Again, this rig includes two cylinders which are located external and parallel to one another. As mentioned above, the side by side configuration of the cylinders results in a bulky and complex drill rig.

Yet another drill rig is described in the specification of DE 198 09 773. Although the drill rig described in this document makes use of a chain drive to obtain an amplitude advantage on the movement of a drill carriage, it only includes a single cylinder and piston assembly which is used to clamp the rig to a wall of a mine working. Instead of using a second cylinder and piston assembly as described with reference to the drill rigs mentioned above, this rig includes two separate chains running in separate planes. The fist chain is used to drive the carriage while the other one is used to drive a mount on which the carriage is mounted. The use of two chain drives is not only complex but also unsuitable considering the working conditions underground in a mine. The uncovered chain drives of the drill rig of DE 198 09 773 could also be a safety hazard to the operator.

It is an object of this invention to alleviate at least some of the problems experienced with existing drill rigs. It is a further object of this invention to provide a drill rig that will be a useful alternative to existing drill rigs.

SUMMARY OF THE INVENTION

According to the invention there is provided a drill rig including:

an extendable thrust cylinder;

an extendable clamping cylinder for clamping the drill rig between a floor and hanging wall of a mine working, the clamping cylinder being mounted inside the thrust cylinder;

a drill carriage which is slidably connected with respect to the thrust cylinder and moveable in a carriage movement direction substantially parallel to the axis of extension and contraction of the cylinders, the carriage being configured to carry a drill in use; and

a flexible, mechanical coupling provided between the drill carriage and the thrust cylinder so that extension and contraction of the thrust cylinder causes the drill carriage to move in the drill carriage movement direction,

wherein the mechanical coupling is configured to provide an amplitude advantage so that the distance of travel of the drill carriage, and hence of a drill carried by the drill carriage in use, is greater than the extension of the thrust cylinder.

The clamping cylinder may be mounted coaxially with respect to the thrust cylinder.

The drill rig may include a pulley arrangement having a number of pulleys on which the flexible coupling in use runs, the pulley arrangement further being carried by the thrust cylinder such that extension or contraction of the thrust cylinder causes the pulley arrangement to move upwards or downwards respectively. Preferably, the flexible coupling is a single cable or rope which in use runs from the drill carriage over the pulley arrangement and around a balancing point before travelling back over the pulley arrangement to the drill carriage where both ends of the rope are fixed to the drill carriage. In the preferred embodiment the balancing point is in the form of a pulley which is located on the outside of the thrust cylinder and arranged substantially perpendicular to the pulleys in the pulley arrangement.

The pulleys in the pulley arrangement may be rotatable independently of one another, thereby allowing the tension in the cable or rope to equalise by rotating.

In an alternative embodiment the flexible coupling may be in the form of two separate belts or a single belt having a slot therein.

The drill rig may further include a telescopic frame assembly for guiding the drill carriage when it is moved between a bottom position wherein it is located near the floor of the mine working and a top position wherein it is located near the hanging wall of the mine working.

Preferably, the telescopic frame assembly includes a stationary inner slide connected to the housing of the thrust cylinder, a slide carriage being slidable with respect to the inner slide, and an outer slide to which the drill carriage is connected, the outer slide being slidable with respect to the slide carriage so that the drill carriage moves along the slide carriage as the outer slide is moved.

In the preferred embodiment the slide carriage is located by means of an external frame mounted about the slide carriage, thereby preventing the slide carriage from rotating in use about a longitudinal axis of the cylinders.

The pulley arrangement may also include a frame from which guide formations extend for guiding the pulley arrangement when it is moved upwards or downwards by the extension or contraction of the thrust cylinder. The guide formations of the pulley arrangement may be guided by the frame assembly to prevent the pulley arrangement from rotating about a longitudinal axis of the cylinders.

The thrust cylinder may be a single acting multi-stage telescopic cylinder.

In another embodiment the thrust cylinder may be a two stage telescopic cylinder including an inner first stage rod and an outer second stage rod, the first stage rod in use engaging the floor of the mine working. In this embodiment the flexible coupling may be connected between the drill carriage and the second stage rod of the thrust cylinder so that extension of the second stage rod causes the drill carriage to move in a generally upward direction, while contraction of the second stage rod causes the drill carriage to move in a generally downward direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a front perspective view of a drill rig according to a first embodiment of the invention including coaxially mounted clamping and thrust cylinders;

Figure 2 shows a rear perspective view of the drill rig of Figure 1 ;

Figure 3 shows a front perspective view of the drill rig of Figure 1 with the clamping cylinder in an extended position;

Figure 4 shows a front perspective view of the drill rig of Figure 1 with the thrust cylinder in an extended position; shows a perspective view of a roller box of the drill rig of Figure 1 ; shows a cross-sectional view of the drill rig of Figure 1 ; shows a shows a side view of the drill rig of Figure 1 with the cylinders shown in different stages of extension in Figures 7(a) to 7(c); shows a perspective view of a drill rig according to a second embodiment of the invention; shows a side view of the drill rig of Figure 8 with the cylinders shown in different stages of extension in Figures 9(a) and 9(b); shows a front perspective view of a third embodiment of the drill rig including coaxially mounted clamping and thrust cylinders; shows a rear perspective view of the drill rig of Figure 10; shows a rear perspective view of the drill rig of Figure 10 without an external frame;

Figure 13 shows a perspective view of a pulley arrangement of the drill rig of Figure 10;

Figure 14 shows a rear perspective view of the drill rig of Figure 10 with both the clamping and thrust cylinders fully extended; and Figure 15 shows a side view of the drill rig of Figure 10 with the cylinders shown in different stages of extension in Figures 15(a) to 15(c).

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Figure 1 shows a first embodiment of a drill rig 10 according to the invention. Although the drill rig 10 could be used for drilling holes for a multitude of different applications it is envisaged that it will find particular application in installing rock bolts in a hanging wall of a mine working. It must be understood that the drill rig 10 may be used in a first operation to drill holes as well as to insert rock bolts in a second operation.

The drill rig 10 includes extendable, coaxial clamping and thrust cylinders which are indicated by the reference numerals 12 and 14 respectively. It can be seen from the figures, in particular Figure 6, that the clamping cylinder 12 is contained coaxially inside the thrust cylinder 14. Essentially the thrust cylinder 14 is annular in shape and located about the clamping cylinder 12 as shown in Figure 6. This configuration assists in reducing the overall size of the drill rig 10. In the preferred embodiment both cylinders are double acting pneumatic cylinders. It is however envisaged that mechanical actuators other than pneumatic cylinders could be used, for example hydraulic cylinders. It is also envisaged that the clamping cylinder may be located inside the thrust cylinder in a configuration other than a coaxial configuration. The clamping cylinder may alternatively be mounted coaxially with respect to the thrust cylinder but not inside it.

The cylinders 12 and 14 share a common base 16 through which air is supplied to them independently in order to extend or contract them. The advantage of supplying the cylinders 12 and 14 independently is they may be operated entirely independently from each other. The clamping cylinder 12 has a clamping rod 18 which is extendable to clamp the drill rig between the floor and hanging wall of the mine working, while the thrust cylinder 14 has a thrust rod 20 which may be extended or contracted to move a drill 22 generally upwards or downwards. Although both 18 and 20 are referred to as rods, it must be understood that they are in fact hollow rods or tubes to allow for the coaxial configuration of the drill as shown in the drawings (see for example Figure 6). It is further envisaged that the clamping rod 18 may have a non-circular profile such as an elliptical profile, for example.

The drill 22 is in use carried by a hinged drill carriage 24 slidably connected with respect to the thrust cylinder 14 and moveable in a carriage movement direction substantially parallel to the axis of extension and contraction of the cylinders 12 and 14. To convert extension or contraction of the thrust cylinder 14 into movement of the drill carriage 24 and accordingly the drill 22, a flexible, mechanical coupling 26 is provided between the carriage and the thrust cylinder. In the embodiment of Figure 1 the coupling 26 is in the form of two belts which are connected to the base 16 and the carriage 24 at either ends, and which run substantially parallel through a pulley arrangement 28. The pulley arrangement 28 is also referred to as a roller box and is, in turn, carried by the thrust rod 20. In this embodiment the belts are manufactured from PVC (Polyvinyl Chloride). The roller box 28 has rollers 30 which act as pulleys in order to provide an amplitude advantage to the movement of the drill carriage 24 in relation the extension of the thrust cylinder 14. It should be clear that in the embodiment illustrated in Figure 1 the amplitude advantage is two i.e. the carriage 24 will move twice the distance of extension of the thrust rod 20. It must however be understood that the amplitude advantage can be increased by including more direction changing pulleys in order to obtain a ratio of for example 3:1 or 4:1.

An advantage of using the flexible, mechanical coupling 26 and slidable drill carriage 24 is that the drill carriage and accordingly the drill 22 may be lifted to a position above the top of the thrust cylinder 14 due to the amplitude advantage. The flexible, mechanical coupling also isolates some of the vibration from the percussion drill 22. While moving upwards and downwards the movement of the drill carriage 24 is guided by means of a telescopic frame assembly 32. As can be seen in Figure 2, the frame assembly 32 has multiple sliding interfaces between slides 34, 36 and 38 which facilitate movement of the drill carriage. Each slide has two separate legs in the form of angle sections which are arranged diametrically opposite each other across the thrust cylinder 14. The innermost slide 34 is fixed with respect to the base 16 and thrust cylinder 34, and guides the movement of the middle slide 36. Top and bottom connecting formations 40 and 42 connect the legs of the middle slide 36 to each other so that they move simultaneously as a single carriage, which is referred to below as the slide carriage. Similarly, the legs of the outermost slide 38 are connected to each other by means of a top and bottom support plate 44 and 46. As shown in Figure 2, the outermost slide and the support plates form part of the drill carriage 24.

Referring to Figure 3 and Figure 4, in which the clamping rod 18 and thrust rod 20 are shown in their fully extended positions respectively, the movement of the drill and slide carriages 24 and 36 will now be described in detail. With the clamping rod 18 in its extended position wherein it anchors against the hanging wall of the mine working the drill carriage 24 is movable upwards by extending the thrust rod 20. Extension of the thrust rod 20 moves the roller box 28 upwards and causes the belts 26 to run over the rollers 30 to move the drill carriage 24 upwards along the slide carriage 36. The slide carriage 36 remains stationary until the top support plate 44 of the drill carriage 24 comes into contact with the top connecting formation 40 of the slide carriage, thereby forcing the slide carriage to slide along the inner slide 34 when the drill carriage is lifted further. The telescopic slide assembly can be seen clearly in Figure 4.

The roller box 28 is located by the slide carriage 36 by means of locating lugs 48 projecting from a frame 50 of the roller box. These lugs 48 run in the inside of the legs of the inner slide 34 and prevent the roller box from rotating about a generally vertical axis. When the thrust rod 20 is fully extended the lugs 48 will be positioned above the uppermost part of the inner slide 34 and will be located by the slide carriage 36. As a result, the roller box 28 will always be prevented from rotating regardless of whether the thrust cylinder is extended or not.

It can also be seen from Figure 5 that the frame 50 has an opening 52 extending through it so that the clamping rod 18 is allowed to pass through the roller box 28. It can further be seen from Figure 5 that the rollers 30 have grooved sections 54 in which the belts 26 run. The grooves 54 are located towards the ends of the rollers so that the belts 26 run on either side of the clamping rod 18. Although two separate belts 26 are illustrated in Figures 1 to 9, it must be clear that different flexible couplings could be used. For example, it is envisaged that in an alternative embodiment a single belt having a slot therein could be used. By using a single belt the load sharing ability will be better i.e. the force distribution between the two sections of the belt on either side of the slot will be generally even.

Referring now to Figure 7 the method of using the drill rig 10 will now be described. The drill rig 10 includes a handle 56 and wheels 58 which are used to move the drill rig into a desired drilling position. Locating formations 60 project from a bottom surface of the base 16 so that in use they engage the floor of the mine working. As shown in Figure 6 there are at least two locating formations to prevent the drill rig from rotating about the longitudinal axis of the clamping rod 18, thereby ensuring alignment between the drill and the hole throughout the drilling process.

Figure 7(a) shows the drill rig 10 after it has been moved into position with both the clamping cylinder 12 and thrust cylinder 14 fully contracted. In this position the drill 22 is in its bottom position in which it is located on or near the floor of the mine working. When the drill rig 10 is in the desired drilling position the clamping cylinder 12 is activated first to extend the clamping rod 18 until it engages the hanging wall of the mine working, thereby locating the drill rig. With the drill rig 10 fixed into position the thrust cylinder 14 is activated next to extend the thrust rod 20. Figure 7(b) shows the thrust rod 20 extended partially while the clamping rod is fully extended. From this figure it can be seen that the roller box 28 moves vertically upwards as the thrust rod 20 is extended, thereby causing the belts 26 to roll lover the pulleys and drill carriage 24 and drill 22 to move upwards as described above.

The thrust rod 20 is extended further to lift the drill carriage 24 and drill 22 into their top positions in which they are located at or near the hanging wall of the mine working. The movement of the drill 22 from its bottom position as illustrated in Figure 7(a) to its top position as illustrated in Figure 7(c) is known as a single drill run. An advantage of the drill rig 10 over currently known single cylinder drill rigs is that it gives an increased drill run as a result of amplitude advantage provided by the belt and pulley arrangement.

Figure 8 shows a drill rig 70 according to a second embodiment of the invention. Like reference numerals designate like features.

The drill rig 70 also has two coaxial cylinders. However, in the second embodiment the thrust cylinder is in the form of a single acting telescopic cylinder 72 also referred to as an air leg. In this embodiment the thrust cylinder 72 is a two stage cylinder including a first stage rod 74 and a second stage rod 76. The flexible belts 26 are connectable to the exterior of the first stage rod 74 and run over a roller box 78 carried, in use, by the thrust cylinder 72. Similarly to the first embodiment the belts connect to a drill carriage (not shown in Figure 8) on which the drill 22 is mounted. It must be understood that extension of the thrust cylinder 72, in particular the second stage rod 74, will drive the drill carriage upward and downward similar to what has been described above.

By using a telescopic air leg 72 to drive the drill carriage and drill 22, there is no need to include a telescopic frame assembly as described above with reference to the first embodiment. The exclusion of the frame assembly has the advantage that the design is simplified significantly. It is envisaged that, in order to prevent relative rotation between the clamping and thrust cylinders, rods of non-circular profile could be used. Alternative means to prevent rotation within in drill rig 70 could also be used.

Figure 9(a) and (b) a side view of the drill rig 70 of Figure 8 with the cylinders shown in different stages of extension. In Figure 9(a) the drill rig 70 is shown in its contracted position before drilling while Figure 9(b) shows the drill rig in its extended position wherein the drill 22 is almost in contact with the hanging wall of the mine working.

In this embodiment the connection point between the belts 26 and thrust cylinder is raised and movable. It can be seen in Figure 9 that the flexible belts 26 connects to a drill carriage 82 which slides on a frame 84 mounted about the exterior of the thrust cylinder 72. In this arrangement the frame 84 is fixed to the thrust cylinder 72 while the drill carriage 82 is moveable substantially vertically.

In use the clamping rod 18 is extended until it engages the hanging wall of the mine working. Thereafter the first stage rod 74 of the thrust cylinder is extended, thereby lifting the drill 22 from its bottom position towards the hanging wall. Once the first stage rod 74 is fully extended the second stage rod 76 is extended in order to lift the drill to its top position above the thrust cylinder. Again the flexible coupling 26 provides an amplitude advantage so that the travel distance of the drill is twice the extension of the second stage rod 76.

It must be understood that the amplitude advantage only applying to the second stage of the telescopic air leg 72 and the inherent annular shape of the coaxial cylinder arrangement allow for the drill to be subject to a constant thrust. This is an advantage over conventional telescopic air legs in which the direct coupling of the drill to the cylinder and the different cross sectional areas of the piston within the cylinder which operate in separate stages do not allow for the drill to be subject to a constant thrust. During the drilling process it may be required to change the drill steel (not shown in the drawings). To replace a drill steel the drill 22 needs to be lowered from its top position and in this embodiment of the invention this is simply done by cutting off the air supply to the thrust cylinder, thus allowing it to contract under the force of gravity.

A drill rig 100 according to yet another embodiment of the invention is illustrated in Figures 10 to 15. Again, like numerals designate like features.

Figures 10 and 11 show a front and rear perspective view of the drill rig 100 respectively. The workings of the cylinder assemblies 12 and 14 are identical to that of the drill rig 10 and will therefore not be described again. However, the telescopic frame assembly and the flexible coupling of the drill rig 100 are different to that of the drill rig 10.

Referring to Figure 12 it can be seen that the telescopic frame assembly 102 has multiple sliding interfaces similarly to that of the drill rig 10. The frame assembly 102 includes a stationary slide 104 which has two tubular sections fixed to the outside of the thrust cylinder 14 by means of clamps 105. The inner slide 104 guides the movement of an intermediate slide 106 which includes four tubular sections 106.1, 106.2, 106.3 and 106.4. Top and bottom connecting formations 108 and 110 connect all four sections to one another, thereby ensuring that they move simultaneously as a slide carriage 112. Two of the inner sections 106.1 and 106.2 are slidably mounted inside the inner slides 104 while the other two sections 106.3 and 106.4 act as guides for an outer slide 114 to which the drill carriage 24 is connected. The outer slide 114 has two tubular sections which are slidably mounted about the intermediate sections 106.3 and 106.4.

The drill rig 100 also includes a modified roller box 116 and mechanical coupling 26 as shown in Figure 13. From this figure it can be seen that a single flexible coupling 26 in the form of a rope or cable is used. The ends of the cable 26 are attached to the drill carriage 24 by means of clamps 120.1 and 120.2 respectively. From the drill carriage 24 the cable 26 runs 2012/050210

15 over pulleys 122.1 and 122.2 located on the roller box 116 and around a balancing point 124, which is in the form of a balancing pulley, after which it travels back over pulleys 122.3 and 122.4 all the way to the drill carriage where it is secured thereto. From the drawings it can be seen that the balancing pulley 124 is arranged substantially perpendicular with respect to the pulleys 122 in the roller box 116.

It must be understood that by using a single rope or cable 26 the force distribution or tension in the two sections of rope running to and from the balancing pulley is equal. The balancing pulley 124 may either be non- rotating (as shown), thereby allowing for slippage of the cable 26 to equalise tension in the cable, or rotating so that the tension is equalised by rotation of the pulley.

In the embodiment the pulleys 122.1 to 122.4 are rotatable independently from one another. This is achieved by mounting a pair of pulleys on either side of spacers 126.1 and 126.2. In the arrangement illustrated in Figure 13 the pulleys 122.2 and 122.3 are mounted on either side of spacer 126.1 while pulleys 122.1 and 122.3 are mounted on either side of spacer 126.2.

It must be understood that rotation of the pulleys allows for equalisation of the tension in the cable 26. It is however envisaged that in an alternative embodiment the pulleys 122 may also be stationary, similarly to the intermediate pulley 124, so that equalisation of the tension in the cable takes place through slippage of the cable over the pulleys as opposed to rotation.

The movement of the drill and slide carriages 24 and 112 will now be described in detail with reference to Figures 14 and 15. Figure 14 shows a perspective view of the drill rig 100 with the clamping rod 18 and thrust rod 20 in their fully extended positions while Figure 15 shows side views of the drill rig 100 during different stages of extension of the cylinders 12 and 14.

As can be seen in Figure 15(a) the drill carriage 24 is in its bottom position near the floor of the mine working when the cylinders 12 and 14 are fully T IB2012/050210

16 contracted. Similarly to the first embodiment of the drill rig 10, the drill rig 100 is clamped into position in the mine working by extending the clamping cylinder 12 as shown in Figure 15(b). With the clamping rod 18 in its extended position the drill carriage 24 is movable upwards by extending the thrust rod 20. The drill carriage 24 remains in its bottom position while the thrust cylinder 14 remains fully contracted. Extension of the thrust rod 20 moves the roller box 116 upwards and causes the cable 26 to run over the pulleys 122 to move the drill carriage 24 upwards along the slide carriage 112. The slide carriage 112 remains stationary until the drill carriage 24 comes into contact with the top connecting formation 108 of the slide carriage, thereby forcing the slide carriage to slide inside the inner slide 104. It must be understood that the drill carriage 24 is in its top position when the thrust cylinder 14 is fully extended. The drill carriage 24 is shown in its top position in Figures 14 and 15(c).

A person skilled in the art of drill rigs will know that the drilling action will impose a torque on the drill carriage 24 about the centre axis of the clamping cylinder 12. To prevent the drill carriage 24 and therefore the sliding carriage 112 from rotating the inner slide 104 is secured by means of an external frame 128. From Figures 10 and 11 it can be seen that the inner slides 104 are fixed to side members 128.1 and 128.2 of the frame 126 by means of connecting formations 130.1 and 130.2. A top connecting portion 132 provides additional strength and support to the side frame members 128.1 and 128.2. The side frame members 128.1 and 128.2 also act as crash bars, thereby protecting the cylinders assemblies. They further provide attachment points for the wheels 58.

It must be understood that the drill rig 100 is completely functional without the external frame 126. The drill rig 100 without the external frame 126 is shown in Figure 12. It is further envisaged that in an alternative embodiment the thrust cylinder 14 could have a non-circular outer profile in order to eliminate the need for an external frame completely. By using a non-circular outer profile such as an elliptical profile, the slide carriage 116 will be prevented from rotating about the thrust cylinder 14. In all of the illustrated embodiments of the invention provision is made for the drill 22 to be swung, slid or rotated out of the way to facilitate the insertion of the next drill steel without moving the drill rig from its clamped position.

A major advantage of the drill rig 10, 70, 100 according to the invention over the prior art drill rigs is that it is lightweight and therefore portable. Due to its lightweight and compact construction a single person is able to move the drill rig around between the required drilling locations. Another advantage of the drill rig 10, 70, 100 according to the invention over the prior art is the equalisation of tension in the flexible coupling.

Claims

1. A drill rig including:

an extendable thrust cylinder;

2. A drill rig according to claim 1 , wherein the clamping cylinder is mounted coaxially with respect to the thrust cylinder.

3. A drill rig according to either claim 1 or 2, including a pulley arrangement having a number of pulleys on which the flexible coupling in use runs, the pulley arrangement further being carried by the thrust cylinder such that extension or contraction of the thrust cylinder causes the pulley arrangement to move upwards or downwards respectively.

4. A drill rig according to claim 3, wherein the flexible coupling is a single cable or rope which in use runs from the drill carriage over the pulley arrangement and around a balancing point before travelling back over the pulley arrangement to the drill carriage where both ends of the rope are fixed to the drill carriage.

5. A drill carriage according to claim 4, wherein the balancing point is in the form of a pulley which is located on the outside of the thrust cylinder and arranged substantially perpendicular to the pulleys in the pulley arrangement.

6. A drill rig according to any one of claims 3 to 5, wherein the pulleys in the pulley arrangement are rotatable independently of one another, thereby allowing the tension in the cable or rope to equalise by rotating.

7. A drill rig according to any one of the claims 1 to 6, wherein the flexible coupling is in the form of two separate belts or a single belt having a slot therein.

8. A drill rig according to any one of claims 1 to 7, including a telescopic frame assembly for guiding the drill carriage when it is moved between a bottom position wherein it is located near the floor of the mine working and a top position wherein it is located near the hanging wall of the mine working.

9. A drill rig according to claim 7, wherein the telescopic frame assembly includes a stationary inner slide connected to the housing of the thrust cylinder, a slide carriage being slidable with respect to the inner slide, and an outer slide to which the drill carriage is connected, the outer slide being slidable with respect to the slide carriage so that the drill carriage moves along the slide carriage as the outer slide is moved.

10. A drill rig according to claim 9, wherein the slide carriage is located by means of an external frame mounted about the slide carriage, thereby preventing the slide carriage from rotating in use about a longitudinal axis of the cylinders.

11. A drill rig according to claim 8, wherein the pulley arrangement includes a frame from which guide formations extend for guiding the pulley arrangement when it is moved upwards or downwards by the extension or contraction of the thrust cylinder.

12. A drill rig according to claim 11 , wherein the guide formations of the pulley arrangement are guided by the frame assembly to prevent the pulley arrangement from rotating about a longitudinal axis of the cylinders.

13. A drill rig according to any one of claims 1 to 12, wherein the thrust cylinder is a single acting multi-stage telescopic cylinder.

14. A drill rig according to any one of claims 1 to 13, wherein the thrust cylinder is a two stage telescopic cylinder including an inner first stage rod and an outer second stage rod, the first stage rod in use engaging the floor of the mine working.

15. A drill rig according to claim 14, wherein the flexible coupling is connected between the drill carriage and the second stage rod of the thrust cylinder so that extension of the second stage rod causes the drill carriage to move in a generally upward direction, while contraction of the second stage rod causes the drill carriage to move in a generally downward direction.