This invention relates to a drilling apparatus. More particularly, this invention relates to a hydraulic “down-the-hole” (DTH) percussion drilling apparatus for drilling holes in a terrain.
Traditionally drilling holes into and through high strength rock types has been most economically performed by percussive drilling systems. These systems fall into one of two categories; either those where the percussion mechanism is located out of the hole (top hammer systems), or those where the percussion mechanism is located in the hole (DTH systems). Top hammer systems require the use of a string of percussion drill rods to transmit force to the rock face. The transmission of percussion shock waves through a series of rods creates limitations as to hole depth and/or drilling accuracy, especially in larger hole sizes, as well as reliability issues. DTH drilling solves the problems associated with top hammer systems by creating the percussion shock waves at the bottom of the hole, where they act directly on the drill ‘bit’ in contact with the rock. Such DTH systems have traditionally been pneumatically powered, using compressed air to transmit energy through the drill rods down the hole to the percussion mechanism at the bottom. Such drilling systems are typically energy inefficient and slow compared to hydraulic top hammer drill systems, especially in smaller hole sizes and/or shallow depths. In an effort to combine the advantages of both top hammer and DTH drilling systems water powered DTH systems have been developed. However these systems have not found widespread use as they suffer from reliability and economic constraints, by using a non-lubricating and potentially corrosive medium (i.e. water) to transmit energy to the percussion mechanism.
EP0233038 and U.S. Pat. No. 5,092,411 disclose the concept of an oil powered DTH drill system. Both of these disclosed drill systems make use of hydraulic hammers fed by external hydraulic hoses clipped into the sides of dedicated drill rods. While the use of an oil powered hammer improves the energy efficiency and reliability of drilling, the arrangements disclosed in these documents suffer from the disadvantage that the external hoses are prone to damage when the hammer is in operation down a hole with resulting unreliability and reduced efficiency in terms of loss of oil and increased operational costs. Operational efficiency is also adversely affected by the complication of reattaching the hydraulic hoses when adding and removing drill rods.
A further source of oil loss with known oil powered drill systems, such as those disclosed in U.S. Pat. No. 5,375,670 and WO96086332, is during coupling and uncoupling of the rods supplying oil under pressure to, and receiving return oil from, the hammer during travel into and out of the drilled hole.
Further loss in efficiency of known hydraulic drill systems, such as that disclosed in JP06313391, can be due to a reduction in impact energy produced and/or reduced cycle speed where the hydraulic accumulator, used to accommodate the varying flow requirements during a cycle of piston extension and retraction, is mounted remotely from the hammer.
A further disadvantage with known hydraulic drill systems is that they are expensive to manufacture and replace when damaged due to the one-piece design of the hammer.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinence of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein; this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in Australia or in any other country.
It is acknowledged that the term ‘comprising’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprising’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
According to a first aspect of the present invention there is provided a drilling apparatus comprising:
It is acknowledged for the purposes of the specification that the term “shuttle valve” means a control valve in fluid communication with hydraulic fluid and used to operate an actuating unit.
Preferably, the drill bit, piston, shuttle valve, accumulator and connection valves are connected substantially in-line to one another.
More preferably, the drill bit, piston, shuttle valve, accumulator and connection valves are modular units connected to one another via locating apertures and locking pins.
Preferably, the first connection valve and second connection valve are individually replaceable.
Preferably, the first connection valve and second connection valve comprise a first connection valve seal and a second connection valve seal respectively which are configured to minimise hydraulic fluid loss during connection and disconnection of each drill rod.
More preferably, the first connection valve and second connection valve are configured so that axial movement of the first connection valve seal and second connection valve seal is less than 20% of the drill rod diameter.
More preferably, the first connection valve and second connection valve are configured so that lateral movement of the first connection valve seal and second connection valve seal is less than 20% of the drill rod diameter.
Preferably, the drill rod also comprises:
Preferably, the return line is an annulus arranged around the pressure line.
Preferably, the flushing line is an annulus arranged around the return line.
Preferably, the pressure line and return line are individually free floating within each drill rod.
Preferably, the pressure line and return line are individually replaceable within each drill rod.
Preferably, the first connection valve and second connection valve are configured to allow for one way flow of return hydraulic fluid away from the hammer.
Preferably, the flushing medium is air.
Preferably, the hammer also comprises an external housing which is adapted to be reversibly fitted to the hammer.
According to another aspect of the present invention there is provided a method of using a drilling apparatus, said method comprising the steps:
Preferably, the method also comprises the step:
Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:
The invention is now described in relation to one preferred embodiment as shown in
For the purposes of clarity fluid interconnections between the various components of the drilling apparatus have been selectively shown in the figures.
The drilling apparatus (1) comprises a hammer (2), at least one drill rod (3, 4), and a rotation device (5). It will be appreciated by those skilled in the art that drill rods (3, 4) may be dispensed with for applications which do not require any distance between the rotation device (5) and the rod connection valve (10). Conversely, any number of drill rods may be used to extend the length of the apparatus (1) as required for a particular application. The rotation device (5) is adapted for connection to a motor and gear system (not shown) to impart rotational movement to the spindle (5A) of the rotation device (5) and the hammer (2) and drill rods (3, 4) in known fashion. The drill system (1) may be continuously rotated in both directions (i.e. clockwise or anticlockwise) by the motor and gear system as indicated by arrow A.
The assembled components (7 to 9) are held within the wear housing (1A) via threads at either end of the housing (1A) into which the drill bit assembly (6) and rod connection valve (10) screw. Thus these internal components (7 to 9) are held in firm contact by the force from these opposing threads at either end of the hammer (2). The housing (1A) may be turned back to front to provide prolonged service life of the hammer (2) to counteract localised erosion damage to the housing (1A) caused by drill cuttings during operation of the drilling apparatus (1).
The drill bit (6) reciprocates over a maximum range of approximately 20 mm via impacts from the piston (7). The drill bit (6) head (6A) has buttons (6B) which contact the rock and form the cutting surface. A range of drill bits of different lengths and diameters may be used to create different hole diameters suitable for different applications and terrains in known fashion.
Each drill rod (3, 4) has a first (17) and second (18) connection valve at its first and second end. First connection valve (17) has a spring loaded poppet valve (19) and seat (20) at the terminus of the pressure oil flow path (14) and spring loaded female poppet valves (21) and seats (22) at the terminus of return oil flow path (15). Similarly, connection valve (18) has a spring loaded poppet valve (23) and seat (24) at the terminus of the pressure oil flow path (14) and spring loaded male poppet valve ring (25) and seat (26) at the terminus of the return oil flow path (15). The positioning of the poppet valve's (19, 21, 23 and 25) proximal to their corresponding seats (20, 22, 24 and 26) minimises loss of oil from the drill rods when the connection valves (17, 18) are disconnected when inserting a new drill rod to extend the length of the string of drill rods down a hole or when dismantling the drill rods (3, 4). The subsequent saving in oil is very significant as this arrangement limits oil loss to only that required for thread and seal lubrication upon coupling and uncoupling, significantly saving costs and reducing environmental impact to an absolute minimum.
The pressure oil flow path (14) and the return oil flow path (15) are each individually ‘free floating’ within each of the drill rods (3, 4) thereby allowing for thermal expansion during use. Pressure oil flow path seal carrier (37) and pressure oil flow seal (38) fitted to the ends of the pressure oil flow path (14) (as shown in
The configuration of poppet valves (19, 21, 23 and 25) allows the hydraulic connections between the flow paths (14, 15) of the respective drill rods (3, 4) to be completed with a relatively small axial engagement distance between the drill rods (3, 4) during connection. This engagement distance is typically no more than 50% of the overall drill rod diameter. As a result of this the seals (27, 28) ‘sweep’ over a very short distance during connection and disconnection of the drill rods (3, 4). This seal engagement distance is typically no more than 20% of the overall rod diameter. This feature minimises wear and tear of the connection valves (17, 18) and seals (27, 28) during connection and disconnection of the components of the apparatus (1). Furthermore, there are no ports or other discontinuities on the sealing surfaces and consequently the seals (27, 28) only ‘sweep’ over smooth, appropriately contoured surfaces during connection and disconnection further enhancing their reliability.
The Rod Connection Valve (10) interfaces between the three concentric flow paths of the drill rod (3) (centre=pressure oil flow path (14), first annulus=return oil flow path (15), second annulus=flushing medium flow path (12), best seen in
It will be appreciated by those skilled in the art that other internal arrangements of the flow paths (12, 13, 14 and 15) may be used without departing from the scope of the present invention.
In use the drilling apparatus (1) is assembled for drilling by the following method steps:
Drilling is commenced by the bit (6B) being brought into contact with the rock face by the hydraulic feed system and hydraulic pressure of 50-200 bar (depending on terrain) being applied to port (5D) of the rotation device (5). Once penetration commences the motor and gear system (not shown) rotates the whole apparatus at 50-150 RPM (depending on hole size and terrain) and the hydraulic feed system applies a feed force of 2-20 kN (depending on terrain) advancing the apparatus into the drilled hole. Once the limit of advance has been reached drilling is stopped by removing the pressure supply from port (5D). If further advance is required the rotation device (5) may be unscrewed from the second connection valve (18) of the last drill rod, and an additional drill rod added. Drilling is then recommenced by applying the same steps as described above.
The apparatus (1) has been trialled by drilling 105 mm diameter holes in hard limestone at a penetration rate of over 1 m/min. Reliable drilling was demonstrated with a minimum loss of hydraulic oil.
Testing on prototype versions of the apparatus (1) show's that oil loss is typically as low as 0.008 litre per connection/disconnection.
Thus, preferred embodiments of the present invention may have a number of advantages over the prior art which can include:
Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.
Number | Date | Country | Kind |
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2008904823 | Sep 2008 | AU | national |
This application is a continuation-in-part application of PCT Application No. PCT/NZ2009/000197, filed on Sep. 17, 2009. The present invention is based on the provisional specification filed in relation to Australian Patent Application No. 2008904823, the entire contents of which are incorporated herein.
Number | Name | Date | Kind |
---|---|---|---|
4828048 | Mayer et al. | May 1989 | A |
5092411 | Hausherr et al. | Mar 1992 | A |
5375670 | Ekwall et al. | Dec 1994 | A |
5823274 | Wisakanto et al. | Oct 1998 | A |
Number | Date | Country |
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0233038 | Aug 1987 | EP |
6313391 | Nov 1994 | JP |
9608632 | Mar 1996 | WO |
WO 9620330 | Jul 1996 | WO |
Number | Date | Country | |
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20120061142 A1 | Mar 2012 | US |
Number | Date | Country | |
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Parent | PCT/NZ2009/000197 | Sep 2009 | US |
Child | 13048243 | US |