LIQUID HAMMER DRILL

Abstract

A liquid hammer drill comprising: a housing; a drill bit at a leading end of said housing wherein said drill bit includes a trailing end and a leading end that defines a cutting portion; a piston member located inside said housing and having a trailing end, a leading end and an intermediate portion therebetween, said piston member being capable of movement between a first position and a second position at which it impacts the trailing end of the drill bit; a liquid circuit for delivering a liquid to the piston member to cause the piston member to oscillate between its first and second positions and transfer the liquid outside the housing via a liquid outlet; a sealing member for isolating the trailing end of the drill bit from the liquid circuit wherein, in use, the piston member impacts the trailing end of the drill bit in a liquid free environment.

Claims

1-20. (canceled)

21. A liquid hammer drill configured for insertion into a cutter head of a tunnel boring machine comprising: (a) a housing; (b) a drill bit disposed at a leading end of the housing the drill bit including a trailing end and a leading end, the leading end defining a cutting portion; (c) a piston member located inside the housing and having a trailing end and a leading end, the piston member configured to move between a first position and a second position, such that in the second position the leading end of the piston impacts the trailing end of the drill bit; (d) a closed liquid circuit for delivering a liquid to the piston member within the housing to cause the piston member to oscillate between the first and second positions; and (e) a sealing member for isolating the trailing end of the drill bit from the closed liquid circuit, such that the piston member impacts the trailing end of the drill bit in a liquid free environment.

22. The liquid hammer drill according to claim 21, wherein the ratio of the length of the liquid hammer drill to its width is less than 6, 5.5, 5, 4.5, 4, 3.5, 3, 2.5 or 2.

23. The liquid hammer drill according to claim 21, wherein the liquid is any one of water, salt water, petroleum and liquefied gas.

24. The liquid hammer drill according to claim 21, wherein the drill bit has a reach of about 50, 60, 70, 80 or 90 mm.

25. The liquid hammer drill according to claim 21, wherein the trailing end of the drill bit defines a strike face for the piston member and the strike face comprises at least one liquid relief groove.

26. The liquid hammer drill according to claim 21, wherein the drill bit comprises at least one aperture to allow for expulsion of any fluid from inside the housing of the drill.

27. The liquid hammer drill according to claim 21, wherein the piston member comprises a main body that narrows toward the leading end.

28. The liquid hammer drill according to claim 21, the piston further comprising an intermediate portion between the leading end and the trailing end, wherein the intermediate portion of the piston member defines a shoulder.

29. The liquid hammer drill according to claim 21, wherein the body of the piston member defines a cavity therein for receiving the liquid of the closed liquid circuit to move the piston member between the first and second positions.

30. The liquid hammer drill according to claim 21, wherein the piston member has a travel distance between the first and second positions or stroke of about 20, 25, 30 or 35 mm.

31. The liquid hammer drill according to claim 21, wherein the closed liquid circuit does not exhaust liquid via the drill bit.

32. The liquid hammer drill according to claim 21, wherein the closed liquid circuit comprises an inlet into the housing and an outlet from the housing to circulate the liquid of the closed liquid circuit within the housing to drive the piston.

33. The liquid hammer drill according to claim 21, wherein the sealing member is located towards the leading end of the piston member.

34. The liquid hammer drill according to claim 21, wherein the sealing member is located between the leading end of the piston member and the housing.

35. The liquid hammer drill according to claim 21, wherein the sealing member is configured to prevent liquid in the closed liquid circuit from contacting the trailing end of the drill bit, to thereby maintain the liquid free environment.

36. The liquid hammer drill according to claim 21, wherein the drill bit has a square shaped cross-section and the cutting portion located at the leading end of the drill bit is square.

37. The liquid hammer drill according to claim 21, wherein the cutting portion supports a plurality of buttons.

38. The liquid hammer drill according to claim 21, wherein a distance between the trailing end and the leading end of the drill bit is between 50-100 mm.

39. A cutter head assembly for a tunnel boring machine, the cutter head assembly comprising: (f) a cutter head including a cutting face; and (g) a plurality of liquid hammer drills according to claim 21 configured to locate within the cutter head.

40. A tunnel boring machine comprising a cutter head and a plurality of liquid hammer drills according to claim 21 configured to locate within the cutter head.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to facilitate a better understanding of the present disclosure, preferred embodiments are described herein with reference to the accompanying drawings, in which:

[0049] FIG. 1 is perspective view of a liquid hammer drill according to one embodiment of the first aspect of the present disclosure including a cut away to show the internal components of the drill;

[0050] FIG. 2A is a perspective view of a drill bit that can form part of the liquid hammer drill of the present disclosure; and

[0051] FIG. 2B is an end view of the trailing end of the drill bit in FIG. 2A.

DETAILED DESCRIPTION

[0052] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout.

[0053] A liquid hammer drill according to one embodiment of the first aspect of the present disclosure is depicted in FIG. 1 and generally indicated by the numeral 10.

[0054] The drill 10 includes a housing 12 and a drill bit 14 at the leading end of the housing 12. The drill bit 14 includes a leading end defining a cutting portion 16 that includes a plurality of ovoid shaped toughened buttons 18. Whilst not shown in FIG. 1, the cutting portion 16 includes an aperture that allows for any ingress fluid (air or liquid) to be expelled.

[0055] The drill bit 14 has a relatively low profile and is removably attached to the housing 12 with a bit retention means in the form of collar 20 that allows for the drill bit 14 to be threaded on to the housing 12. The trailing end 22 of the drill bit 14 defines a strike face that is described further hereunder.

[0056] The drill 10 further comprises a piston member in the form of piston 24, located inside the housing 12. The piston 24 has a generally circular cross-sectional shape and has a trailing end 26 that defines a cavity 28, a leading end 30 and an intermediate portion therebetween that defines a shoulder 32. The leading end 30 is tapered or narrower relative to the trailing end 26. The piston 24 is capable of movement between a first position and a second position at which the leading end 30 impacts the trailing end 22 of the drill bit 14 and is operable by a liquid circuit that delivers liquid to the piston member via inlet 34 and transfers the liquid outside the housing via outlet 36. Conventionally, liquid is exhausted to the cutting face of the drill bit 14 but the present disclosure allows for the exhaust of the liquid to be captured via the outlet 36. Thus, the liquid is contained and exits the housing via outlet 36 so it can be delivered back to the drill via inlet 34. This represents an essentially closed liquid circuit.

[0057] Between the inlet 34 and outlet 36 is a flow controller in the form of a valve 38. Liquid, such as water, is delivered to the drill via inlet 34 and differential pressure between the inlet 34 and outlet 36 causes the valve 38 to move between first and second positions that in turn creates a pressure differential that causes the piston 24 to oscillate between its first and second positions and repeatedly strike the trailing end 22 of the drill bit 12: the frequency of the oscillation being a product of the differential pressure. This oscillating movement corresponds to that widely used in water hammer drills and is familiar to those skilled in the art.

[0058] When the piston 24 strikes the trailing end 22 of the drill bit 14, it does so in a substantial liquid free environment. The substantial liquid free environment is a result of the action of the sealing member in the form of the O-ring seals 40 that isolate the trailing end 22 of the drill bit 14 from the water. Although some water may pass the O-ring seals 40 any such ingress does not overly compromise the operation of the drill 10.

[0059] An alternate embodiment of the drill bit that forms part of the drill according to the first aspect of the present disclosure is depicted in FIGS. 2A and 2B and generally indicated by the numeral 114.

[0060] The drill bit 114 also has a relatively low profile and a relatively short bit reach of about 70 mm and is adapted to be threaded onto the housing via a threaded engagement on collar 180. The drill bit 114 has a generally square shaped cross section but incorporates an irregular shaped outside edge created by a plurality of cut-outs 162 that form a scalloped edge. The cutting face of the drill bit 114 includes a plurality of buttons 118 of toughened material and a pair of grooves 160a, 160b that run diagonally across the cutting face and assist with the removal of material away from the cutting face during use. At the centre of the cutting face is an aperture 170 that allows for any fluid (air or liquid) to be expelled from inside the housing of the drill.

[0061] The trailing end of the drill bit 114, best shown in FIG. 2B, includes a pair of water relief grooves 172a, 172b to manage any liquid ingress to the trailing end of the drill bit 114. A locating member in the form of a series of splines 174 located around the periphery of the inside of the collar 180 assist with the location and engagement of the drill bit 114.

[0062] Advantages, in use, of the present disclosure including one or more of the performance features in the table below where #1, #2 and #3 represent 3 different embodiments of a drill according to a first aspect of the present disclosure:

TABLE-US-00001 #1 #2 #3 Units Pressure Differential 1500 2000 2500 Psi Piston Stroke 30.0 30.0 30.0 mm Piston Mass 255.0 255.0 255.0 Kg Bit Mass 135.0 135.0 135.0 Kg Piston/Bit Wt Ratio 1.89 1.89 1.89 Piston Velocity at Impact 4.20 4.83 5.39 m/s Impact Energy 2251 2976 3701 J Bit Velocity after Impact 7.94 9.13 10.18 m/s Impact Energy 4252 5622 6991 J Number Of Strokes/Second 7.35 14.28 18.37 Hz Valve Velocity Up 6.17 7.13 7.98 m/s Valve Velocity Down 6.28 7.24 8.09 m/s Flow rate 25.4 49.4 63.6 (US) GPM 96.3 187.1 240.7 L/min No of buttons in bit 40 40 40 Impact Energy per button 106 141 175 J

[0063] Those skilled in the art will appreciate that the disclosure described herein is susceptible to variations and modifications other than those specifically described. The disclosure includes all such variation and modifications. The disclosure also includes all of the steps and features referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more of the steps or features.

[0064] Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference, which means that it should be read and considered by the reader as part of this text. That the document, reference, patent application or patent cited in this text is not repeated in this text is merely for reasons of conciseness.

[0065] None of the cited material or the information contained in that material should, however be understood to be common general knowledge.

[0066] The present disclosure is not to be limited in scope by any of the specific embodiments described herein. These embodiments are intended for the purpose of exemplification only. Functionally equivalent products and methods are clearly within the scope of the disclosure as described herein.

[0067] The disclosure described herein may include one or more range of values (e.g. size etc). A range of values will be understood to include all values within the range, including the values defining the range, and values adjacent to the range which lead to the same or substantially the same outcome as the values immediately adjacent to that value which defines the boundary to the range.

[0068] Throughout this specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0069] Other definitions for selected terms used herein may be found within the detailed description of the disclosure and apply throughout. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the disclosure belongs.