Field Of The Invention

THIS INVENTION relates, broadly, to a rock drill guide. More particularly, but not exclusively, the invention relates to a rock drill guide with noise damping properties.

Background To The Invention

Typically, rock drills tend to be heavy and awkward to control. This is often exacerbated by the orientation of, and inertia associated with, the operation and powering of rock drills. Cumulatively, these aspects render rock drills cumbersome to operate and manoeuvre - both in holding and in operation, sometimes requiring more than a single operator to manoeuvre the rock drill optimally. This hampers both the accuracy and precision of achieving substantially straight-line drilling.

A further disadvantage associated with conventional rock drills is the difficulty of retracting the drill bits after engagement into a rock face.

Yet a further disadvantage associated with conventional rock drills relates to the unacceptably high levels of noise pollution that are generated in operation. Object Of The Invention

It is an object of the present invention to provide a guide that will overcome, at least partially, the disadvantages described above.

Summary Of The Invention

According to a first aspect of the invention, there is provided a rock drill guide comprising:

• a sleeve, having an internal chamber, adapted to receive a rock drill therein, the sleeve terminating in an operative end and a drilling end, the sleeve further being connectable to a pressure source for pressurising the sleeve;

• a first seal, located proximate the operative end, and a second seal located proximate the drilling end, the seals cooperating to seal the sleeve substantially hermetically, so as to maintain the pressurisation of the sleeve; and

• a pressure control mechanism, for selectively pressurising the chamber.

The pressure control mechanism may further include a valve, the valve being selectively operable between an open position, in which fluid is forced into the chamber where it is trapped, and a vent position, in which the fluid is evacuated from the chamber. Thus, it will be appreciated, selective engagement of the valve into the open position thrusts the first seal towards the drilling end, and selective engagement of the valve into the vent position permits free movement of the first seal against the direction of thrust.

Preferably, engagement of the valve into the open position directs pressurised fluid onto the first seal resulting in a thrust force directed substantially inline of the drilling action.

The pressure source may be selected from the group consisting of: pneumatic media, including air, hydraulic media, including oils, water, and electrically-powered pressurisation.

In a preferred embodiment of the invention, the pressure source is compressed air.

The sleeve may be substantially elliptical in cross-section, alternatively the sleeve may be non-circular in cross-section.

The seals may be manufactured from plastic materials selected from the group consisting of: high-density polyurethane, low-density polyurethane, rubbers, and elastomeric materials.

The guide may further include a damper, proximate the drilling end, for damping the sound emitted from that end in operation. The clamper may include a series of scatter ports through which exhaust gas is evacuated into the atmosphere.

The guide may further include a boom support, coupled to the sleeve in substantially perpendicular arrangement, for selective adjustment of the horizontal position of the sleeve relative to a footwall, alternatively a hanging wall of a stope.

The boom support may further be adapted for selective adjustment of the vertical position and angle of the sleeve relative to the rock face.

The boom support may be operated by use of pneumatic media, alternatively by use of hydraulic media, further alternatively, electronic-power.

According to a second aspect of the invention, there is provided a kit comprising:

• a rock drill guide which includes a sleeve having an internal chamber, adapted to receive a rock drill therein, the sleeve terminating in an operative end and a drilling end, the sleeve further being connectable to a pressure source for pressurising the sleeve, a first seal, located proximate the operative end, and a second seal located proximate the drilling end, the seals cooperating to seal the sleeve substantially hermetically, so as to maintain the pressurisation of the sleeve, and a pressure control mechanism, for selectively pressurising the chamber; and • a rock drill that is dimensioned and configured to be received within the chamber.

Preferably, the rock drill guide of the kit is a rock drill guide as defined in the consistory statements above.

Brief Description Of The Drawings

In order to describe the invention, embodiments thereof are described hereunder, purely as examples, without limiting the scope of the invention, wherein:

Figure 1 is a longitudinal cross-sectional view of a guide in accordance with the invention, incorporating a rock drill therein;

Figure 2 depicts a sequential series of longitudinal cross-sectional views

(denoted figures 2.1 - 2.4) of the guide in use;

Figure 3 is a plan view, from above, of the damper portion of the guide, in expanded form; and

Figure 4 is a longitudinal cross-sectional view of a guide in accordance with an alternative embodiment of the invention, incorporating a rock drill therein, corresponding to the view depicted in Figure

2.1. Detailed Description Of The Drawings

Referring to the figures, which depict a preferred embodiment of the invention, a rock drill guide in accordance with the invention is provided, and is referred to generally by numeral 10. The guide 10 includes a sleeve 20 which, in assembled form, includes an internal chamber 30. In a preferred embodiment of the invention, the chamber 30 is elliptical in cross-section and is dimensioned to to receive a rock drill 40 within it. In other embodiments of the invention, the chamber 30 is non-circular in cross-section. The sleeve 20 has two ends, referred to conveniently as an operative end 50 - which is the end closest to the operator (not depicted) in use, and a drilling end 60 - which is the end closest to the drill steel 70 in use. The sleeve 20 is sealed at its two ends 50, 60 by corresponding O-ring seals 170, thus the seals 170 form a closed cylinder in combination with the sleeve 20. Furthermore the rock drill 40 is sealed at its two ends 50, 60 by corresponding elliptically-shaped seals 80.

The seals 80, preferably, are manufactured from high density polyurethane. Ideally, in the production stage, these seals 80 are manufactured as a unitary component that are dimensioned and configured to fit over the entire rock drill 40; effectively creating a plug. However, in other embodiments of the invention, it is envisaged that other suitable materials may be used, including: high-density polyurethane, low-density polyurethane, rubbers, and other elastomeric material. In a preferred embodiment of the invention in operation, the sleeve 20 is connected to a pressure source (not shown) via thrust valve 90. The pressure source, ideally, is a supply of compressed air. (However, in other embodiments of the invention, other pneumatic media are used, as are hydraulic media, including oils, water.

Another embodiment of the invention is illustrated in figure 4. In this embodiment, the valve bank 90 is positioned remotely from the guide 10. In this fashion, the valve bank 90 is not positioned on the operative end 50 itself, but is rather connected to the operative 50 end via transmission hoses 150. This embodiment presents further safety advantages over the embodiment described above in that, when the invention is used, the operator would be positioned even further away from the rock face 120 and from the immediate source of noise emanating from the rock drill 40 itself.

The rock drill 40 itself is powered via coiled feed line 100, the selective operation of which is controlled by the operator via drill valve 110, located towards the drilling end 60, and is described in further detail below. Typically, although not exclusively, the rock drill 40 is air-powered.

In the embodiment depicted in Figure 4, it will be noted that an alternative feed line 100 arrangement is depicted. More specifically, in order to avoid any constraints relating to coiling and/or volume restrictions of the feed line 100 within the sleeve 20, an alternative embodiment is shown in which instead of an internal, single coiled feed line, a series of four transmission hoses 150 is used. (While four hoses 150 are used in the embodiment depicted, it will be appreciated that any convenient number of hoses 150 may be used). As has been mentioned above, the valve bank 90 is connected to the operative 50 end via transmission hoses 150 and, in this embodiment, the rock drill 40 is powered via transmission hoses 150, the selective operation of which is controlled by the operator via drill valve 110.

Other than the differences in feed line 100 and hoses 150, as depicted in Figure 2 and Figure 4 respectively and described above, there is no further difference in the method of operation of the invention in the two embodiments.

From the alternative embodiment depicted in Figure 4, water line 200 is also readily discernible. The water line 200 is a conventional water line that is used in the operation of a rock drill 40.

Operation of the invention occurs as follows, as is best depicted, schematically and successively, in figures 2.1 - 2.4. First, the rock drill 40 is positioned within the sleeve 20, with its drill steel 70 facing the exposed rock face 120 that is to be drilled, and with noise damper 140 abutting the rock face 120 (the damper 140 is discussed separately, and in greater detail, below). Conveniently, this drill-and-sleeve assembly is mounted on a boom support 130, which is self-supported between the foot wall (not illustrated) and hanging wall (not illustrated) using an extendable pneumatic cylinder (not illustrated). The book support 130 is coupled directly to the sleeve 20, in perpendicular fashion. The boom support 130 is selectively adjustable in order to achieve the precise desired horizontal, vertical and angular position of the sleeve 20 above a footwall (not shown) and/or below a hanging wall of a stope (not shown). The boom support 130 is operated by use of pneumatic media, preferably air (not shown). However, in other embodiments, it is operated by use of hydraulic media such as oils, and also by electrical-power.

When drill valve 110 is opened, the rock drill 40 is powered-up, causing the drill steel 70 to rotate and percussion to activate, in the conventional fashion, however the rock drill 40 is constrained from rotation by seals 80, and as a result of the non-circular shape of the boom 130. Exhaust gases from the rock drill 40 start venting in the chamber 30, and travel in the direction of the drilling end 60.

Ideally, valve 90 is located proximate the operative end 50 and, certainly, in that portion of the chamber 30 marked as "X" (see figure 2.4) The rock drill 40 is advanced, from its starting position proximate the operative end 50, by opening the thrust valve 90 and supplying pressurised air into the chamber 30, behind the seal 80 proximate the operative end 50. Pressurising the chamber 30 in this fashion results in a force being generated onto that seal 80, in a piston like-fashion, which advances the rock drill 40 toward the rock face 120 in the direction of arrow "A". The rock face 120 is then drilled in the conventional fashion. Significantly, the direction of thrust that is applied behind seal 80 is inline, that is: directly perpendicular to the rock face 120. In this way, the angle of thrust operating on the rock drill 40 is eliminated and this has been found to produce penetration rates which surpass those achievable by conventional hand held rock drills, as the following tables of test data will confirm:

It will also be appreciated by the person skilled in the art that the presence of the continuous sleeve 20, surrounding and enveloping the rock drill 40, necessarily constrains lateral movement and oscillation of the rock drill 40 diverting from the desired line of motion of the rock drill 40 in its direction of motion towards the rock face 120 (arrow "A").

Once the hole depth has been achieved, in order to retract the rock drill 40 out of the rock face 120, the thrust valve 90 is moved to the vent position, thus permitting the trapped fluid in the pressurised chamber 30 to be vented to atmosphere. When this occurs, the pressure in that portion of the chamber shown as Ύ" is greater than the pressure in that portion of the chamber shown as "X" (see figure 2.4), which results in the rock drill 40 retracting freely in the direction of arrow "B" towards the operative end 50. There, the power supply to the rock drill 40 may be deactivated by closing the appropriate valve 110.

Insofar as the noise damping characteristics of the invention are concerned: the guide 10 also includes a damper 140 proximate the drilling end 60, for damping the sound emitted from that end 60 in operation. The damper 140 includes a series of scatter ports 160 through which exhaust gas is disseminated.

More specifically: in operation, the rock drill 40 exhausts into that portion of the chamber 30 marked as "Y" in figure 2.4, in front of the drill steel, proximate the drilling end 60. From there, the gas exhausts from the chamber 30, via an exhaust exit port 150 (best viewed in figure 3), into the damper 140. The damper 140 includes a series of scatter ports 160 which allow the exhaust gases to vent to atmosphere (illustrated by arrows "C"). The presence of this damper 140 has been demonstrated to provide substantially lower noise levels than conventional rock drills alone produce, as the following tables of data reflect:

The invention extends, further, to a kit comprising: a rock drill 40 and a guide 10, as described above.

It will be noted that the invention demonstrates a number of advantages over the prior art. For example: the accurate drilling that is achieved results in a correspondingly efficient rock-breaking process. Further, hanging walls are undamaged by sockets, since these become unnecessary for purposes of using the present invention. Finally, the safety advantages will be self-evident, in that the rock drill operator is able to position himself further away from the rock face than it achievable using conventional rock drills.

It will be appreciated that numerous embodiments of the invention could be performed without departing from the scope of the invention as defined in the consistory statements above.