AU2008211808B2

AU2008211808B2 - Drilling tool

Info

Publication number: AU2008211808B2
Application number: AU2008211808A
Authority: AU
Inventors: Ioannis Bournazos; Jorma Kalliomaki; Aulis Kataja
Original assignee: Sandvik Mining and Construction Oy
Current assignee: Sandvik Mining and Construction Oy
Priority date: 2007-02-01
Filing date: 2008-01-30
Publication date: 2011-04-28
Anticipated expiration: 2028-01-30
Also published as: CN101600848A; CA2675842A1; ZA200905044B; FI20075066A7; EP2137373A1; FI20075066A0; FI20075066L; RU2009132669A; WO2008092994A1; AU2008211808A1; JP2010518278A; US20100000797A1

Description

-2 DRILLING TOOL BACKGROUND OF THE INVENTION The invention relates to a drilling tool for drilling soft and fragmented rock. 5 Presently, when soft and fragmented rock is drilled, typically either a grooved guide tube or a separate protective tube is used, which is either left in the hole or withdrawn from the hole after the drilling. The intention is to prevent the material surrounding the hole 10 from caving in to enable the withdrawal of the drill bit from the hole as the last action. A prior art drawback is that when a grooved guide tube is used, the grooved portions of the tube may break the wall of the hole, which makes the hole cave in 15 regardless of the intention to the contrary. Furthermore, if a separate protective tube is used, extra equipment is required for installing and disassembling the protective tubes. SUMMARY OF THE INVENTION 20 The invention provides a drilling tool for drilling soft and fragmented rock, comprising: a portion having a circular cross section and a smooth outer circumferential surface wherein the outer surface is concentric about a central axis of the tool; 25 a first part at an up hole end of the tool which converges from the portion toward the central axis; and, a plurality of conduits formed in the portion and opening onto an outer surface of the first part wherein fluid is able to flow through the conduits internal of the 30 outer circumferential surface between a down hole end of the drilling tool and the up hole end of the drilling tool, the drilling tool being arranged so that in use the 2620803_1 (GHMatters) 30/03/11 -3 drilling tool located about a drill rod and a drill bit for cutting the rock is down hole of the drilling tool. Thus in an embodiment of the invention that the drilling tool has a smooth outer surface that is 5 positioned symmetrically relative to the central axis of a drill rod and comprises at least one converging end such that during the rotation' of the drill rod it penetrates through the material that tends to cave in and simultaneously compresses and grinds the material tightly 10 against the wall of the drill hole. The through-going conduits allow a fluid such as a rinsing medium is allowed to flow away from the drill hole. An advantage of an embodiment of the invention is 15 that during the drilling of soft or fragmented material, the drill hole can be kept open, as the tool compresses the detaching material tightly into the wall of the drill hole. A further advantage of an embodiment of the invention 20 is that since the flow of rinsing medium is arranged through the drilling tool, and not along the grooves on its outer surface, the flow of rinsing medium does not corrode or detach material from the wall of the drill hole very easily, and thus prevents cave-ins in a ready-made 25 hole. A still further advantage of an embodiment of the invention is that if for some reason the drill hole caves in, it can be opened quite easily by means of the drilling tool. 30 BRIEF DESCRIPTION OF THE FIGURES The embodiments of the invention will be described in more detail in the attached drawings, wherein 2620803_1 (GKMatters) 30/03/11 Figure 1 schematically shows an embodiment of a drilling tool installed in a drill rod, Figure 2 schematically shows an embodiment of a drilling tool seen from above, 5 Figure 3 schematically shows the drilling tool shown in Figure 2 in the longitudinal direction in section along line A - A, Figure 4 shows another arrangement of an embodiment of the drilling tool, and 10 Figure 5 shows still another arrangement of an embodiment of the drilling tool. In the figures, some embodiments of the invention are shown in a simplified manner for the sake of clarity. In the figures, like parts are denoted with the same 15 reference numerals. DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION Figure 1 shows an embodiment of the invention where a drilling tool is installed on a drill rod. It shows a short drill rod 1, one end of which comprises an external 20 thread 2 for fastening a drill bit, the other end comprising an internal thread 3 for fastening a second drill rod. A drilling tool 4 is fastened onto the drill rod 1. In this embodiment, the drilling tool 4 is installed on a separate short drill rod 1 which is 25 intended to be installed between a normal drill bit and a drill rod of a normal length. The tool 4 has a portion of a circular cross section and first and second parts 4a at up hole and down hole ends of the tool respectively which converge from the portion toward a central axis of and 30 connected to the drill rod in a manner generating a smooth, even surface. The purpose of this is to make the shape of the drilling tool 4, when it hits the wall of a 2620803_1 (GHMatters) 30/03/1 -5 caved-in drill hole or a drill hole tending to cave in, compress the detaching or detached material against the wall of the drill hole, its cylindrical part, when the drill rod is rotating, as if compressing the wall firmly 5 and tightly together. Figure 1 further shows openings 5 at the converging part 4a at both ends of the drilling tool 4. The openings 5 are interconnected by means of a conduit described later in connection with Figure 3, allowing rinsing medium to flow between the ends of the drilling 10 tool 4 without the rinsing medium having to flow from between the outer surface of the drilling tool and the surface of the hole. Typically, such a rinsing medium flow may cause caving in of the walls of a hole. Figure 2 schematically shows a drilling tool seen 15 from the end. The cross section of the portion of the drilling tool 4 between the converging parts 4a is substantially cylindrical and the tool has a smooth surface. A maximum outer diameter of the tool may be dimensioned in a manner making it slightly smaller than a 20 maximum outer diameter of the drill bit intended to be used therewith. The reason for this is to allow the tool to pass through a hole made by the drill bit in a hole drilled in a potentially hard rock. It also shows how a plurality of conduits 5a lead through the drilling tool 4 25 for allowing rinsing medium to flow out of the drill hole. Figure 2 also shows a conduit la in the middle of the drill rod 1, along which conduit the rinsing medium flows to the drill bit and further through conduits therein to the drill hole for transporting drilling residue out of 30 the drill hole. Figure 3 schematically shows the drilling tool according to Figure 2 in the longitudinal direction in section along line A - A. As it shows, the openings 5 are at the ends of the conduit 5a inside the drilling tool. A 35 suitable number of such conduits, e.g. 6 or less or more, may be positioned around the axis of the drilling tool. 26208031 (GHMatter.) 30/03/11 -6 The number and the common cross-sectional area of the openings can be arranged to enable the outflow of the rinsing medium and the material transported therewith. The cross section of the conduits passing through the drilling 5 tool may be, not only round, but also of another shape, such as angular, oval, etc. Similarly, the edges of the opening may be inclined inwards, allowing them to push the material outwards from the openings when hitting it. Figure 4 schematically shows another embodiment of 10 drilling tool. Here, the drilling tool is arranged at one end of a drill rod 1 of a conventional length, close to the external thread 2 such that it is positioned almost immediately after the drill bit, when the drill bit is fastened to the drill rod 1. This being so, the control 15 and operation of the drilling rig are as in normal drilling, and no separate short drilling for using exclusively the drilling tool is required at the beginning of the drilling. Figure 5 schematically shows still another embodiment 20 of a drilling tool. Here, the drilling tool is composed as an entity integrated into the drill bit 6. Here, the conduits for removing rinsing medium and drilling residue naturally pass straight through the drill bit and the tool part. 25 In the above description and in the drawings, the invention is only described by way of example and in no way restricted thereto. In some cases, the characteristics disclosed in the present application may be utilized as such, irrespective of other characteristics. On the other 30 hand, when desired, the characteristics disclosed in the present application may be combined for generating different combinations. The drilling tool may be fastened onto the drill rod in a plurality of manners known per se. For example, the drilling tool may be pushed onto the 35 drill rod and then welded thereto at its ends, followed by 2620803_1 (G)4MatterO) 30/03/11 -7 finishing of the surface suitably smooth. Alternatively, the drilling tool, preferably comprising only a short drill rod, may be directly machined as a solid entity, for example. Other manners of manufacture and fastening are 5 also usable. Thus in some embodiments the drilling tool is formed separately from the drill rod and subsequently attached thereto while in other embodiments the drilling tool is formed integrally with the drill rod. In either case when the drilling tool is in use the drill rod 10 extends axially through the tool and the drill bit is located down hole of the tool. The drawings and the related description are only intended to illustrate the idea of the invention. The details of the invention may vary within the scope of the 15 claims. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as 20 "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 2620803_1 (GHMatters) 30/03/11

Claims

1. A drilling tool for drilling soft and fragmented rock, comprising: a portion having a circular cross section and a 5 smooth outer circumferential surface wherein the outer surface is concentric about a central axis of the tool; a first part at an uphole end of the tool which converges from the portion toward the central axis; and, a plurality of conduits formed in the portion and 10 opening onto an outer surface of the first part wherein fluid is able to flow through the conduits internal of the outer circumferential surface between a down hole end of the drilling tool and the up hole end of the drilling tool, the drilling tool being arranged so that in use the 15 drill tool locates about a drill rod and a drill bit for cutting the rock is locatable down hole of the portion.

2. A drilling tool according to claim 1, further comprising a second part at the down hole end of the drilling tool that converges from the portion towards the 20 central axis and wherein the conduits also open onto an outer surface of the second part.

3. A drilling tool according to claim 2 further comprising a drill rod extending axially through the portion, the drill rod having a first thread near the 25 first part for connecting to a further drill rod.

4. A drilling tool according to claim 3 wherein the drill rod comprises a second thread near the second part for connection to a drill bit.

5. A drilling tool according to claim 3 or 4 wherein 30 the portion and the drill rod are formed separately of each other and subsequently attached together.

6. A drilling tool according to claim 3 or 4 wherein the portion and the drill rod are integrally formed from a 2620803_1 {GHMatters) 30/03/11 -9 solid entity.

7. A drilling tool according to any one of claims 1 to 6 wherein the portion is substantially cylindrical.

8. A drilling tool as claimed in any one of claims 1 5 to 3, further comprising an integrally formed drill bit at a down hole end of the portion.

9. A drilling tool as claimed in any one of claims 1 to 7 wherein a maximum outer diameter of the portion is dimensioned to be smaller than a maximum outer diameter of 10 a drill bit coupled to the tool.

10. A drilling tool according to claim 8 wherein a maximum outer diameter of the portion is dimensioned to be smaller than a maximum outer diameter of the drill bit.

11. A drilling tool according to any one of claims 3 15 to 10 wherein the drill rod is provided with an axial hole capable of delivering fluid to a location down hole of the portion.

12. A method of drilling in soft and fragmented rock comprising: coupling an up hole end of a drilling tool in 20 accordance with any one of claims 1 to 10 to a rock drill and operating the rock drill to rotate the drilling tool and wherein the first part of the drilling tool is exposed to a wall of a hole being drilled.

13. A drilling tool substantially as described herein 25 with reference to the accompanying drawings.

14. A drilling tool substantially as described herein in combination with a drill bit. 2620803_1 (GHMatters) 30/03/11