WO2020188530A2 - A drill hammer - Google Patents
A drill hammer Download PDFInfo
- Publication number
- WO2020188530A2 WO2020188530A2 PCT/IB2020/052578 IB2020052578W WO2020188530A2 WO 2020188530 A2 WO2020188530 A2 WO 2020188530A2 IB 2020052578 W IB2020052578 W IB 2020052578W WO 2020188530 A2 WO2020188530 A2 WO 2020188530A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- chamber
- piston
- control tube
- divider
- drill hammer
- Prior art date
Links
- 238000011010 flushing procedure Methods 0.000 claims description 11
- 238000004891 communication Methods 0.000 claims description 2
- 230000009977 dual effect Effects 0.000 description 9
- 238000010276 construction Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000009527 percussion Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B4/00—Drives for drilling, used in the borehole
- E21B4/06—Down-hole impacting means, e.g. hammers
- E21B4/14—Fluid operated hammers
Definitions
- the invention relates to a pneumatic down- or in-the-hole drill hammer with a unique percussion mechanism that applies to both embodiments that have a foot valve tube on the drill bit (referred to as a tube design) and also to tubeless designs (which have a piston stem that interacts with a piston stem bush).
- Down- or in-the-hole drill hammers are well known and extensively used to drill or bore holes in rock.
- Various constructions for these hammer mechanisms have been proposed to achieve supply and exhaust of pressurised air to and from drive and return chambers to cause a piston to reciprocate and impact a drill bit.
- a control tube extends from a back-head and moves into and out of a piston bore as a finger valve to respectively seal and vent (or exhaust) the drive chamber.
- a flushing mode is required wherein the piston ceases its reciprocation. It is generally desirable and advantageous for a drill hammer to be of relatively simple and/or lightweight construction and to have relatively few parts and, especially in recent times, be capable of achieving a low carbon footprint.
- the hammer should also be capable of cost effective manufacture and/or efficiency in use.
- an air distribution chamber provided as an axial, elongate cavity formed into the first end of the piston with an axial bore of reduced diameter extending along the piston from the air distribution chamber to the second end;
- control tube that extends from the back-head co-axially with the chamber divider to slidably engage inside the piston bore;
- the invention further provides for the air distribution chamber to have a distribution port that extends to an exterior of the piston and is locatable [at respective drive and return phases of a drill cycle] in communication with a drive chamber supply cut-out in a wear sleeve or a return chamber supply cut-out in the wear sleeve.
- control tube to be supported inside the chamber divider and for the air supply passage to the distribution chamber to be provided between the control tube and the chamber divider; for the exhaust port to be provided by a laterally arranged conduit; and for the conduit to extend across the air supply passage.
- a spring biased check valve to be supported by the control tube; and for the check valve to have a stem that slides within the control tube and a head spring biased against a seat provided by the back- head.
- the chamber divider to be clamped against a rearwardly disposed shoulder by the back-head [the shoulder may be provided in the wear sleeve or by an inner component of a two-part back-head]; and for the control tube to be secured by a radial support with openings to the air supply passage that engages into an open back end of the chamber divider.
- a further feature of the invention provides for the drive chamber supply cut-out to extend to adjacent the back-head [to provide increased drive chamber volume]
- a further feature of the invention provides for a working area on the piston inside the air distribution chamber around the axial bore to provide a biasing force that serves to move the piston into a flushing mode.
- a further feature of the invention provides for a spring biased check valve to be supported by the control tube; and for the check valve to include a by-pass extending from a downstream side of a valve closure and along a valve spindle to exit inside the control tube.
- the by-pass of the check valve is preferably fitted with an orifice.
- a further feature of the invention provides for the distribution port to open into an annular, circumferential recess.
- the return chamber may exhaust through a foot valve tube on a drill bit or past a piston stem bush.
- Figures 1-2 show a cross-sectional side view of an embodiment of a hammer with a foot valve tube
- Figures 3-4 shows a cross-sectional side view of an embodiment of a hammer with a piston stem and piston stem bush
- Figure 5 shows an enlarged cross-sectional side view of a dual tube provided by chamber divider and control tube with check valve, from Figures 1-4;
- Figure 6 shows a modification to the check valve of Figure 5.
- the drill hammer (1) is provided with a dual tube arrangement that includes a control tube (2) located concentrically inside a cylindrical chamber divider (3).
- a preferred construction of these dual tube components for implementing the invention is shown separately in Figure 5.
- the chamber divider (3) includes an annular flange (4) that is clamped against a shoulder (5) in a wear sleeve (6) by a back-head (7).
- the flange could alternatively be clamped between components of a two-part back-head that are screwed together.
- the control tube (2) includes a radial support (8) with openings that lead from a plenum (9) around a check valve and inside the back-head (7) to an air supply passage (11) that extends between the chamber divider (3) and control tube (2).
- the support (8) engages with a press-fit into an enlarged portion of an opening at a rear end of the chamber divider (3), which provides an inlet to the air supply passage (11).
- the chamber divider (3) and control tube (2) of the dual tube extend from the back- head (7) that secures these components in the assembly and into a distribution chamber (12) provided in a recess or axial cavity formed into a first end (13) of a reciprocating piston (14).
- the distribution chamber (12) is stepped outwardly from a reduced diameter axial bore (15) that extends to a second end (16) of the piston (14).
- the dual tube includes two passages:
- control tube (2) that serves to carry exhaust air away from a drive chamber (18).
- the purpose of the dual tube is accordingly twofold: firstly, to deliver compressed air to distribution chamber (12); and secondly, to convey exhaust air from drive chamber
- the control tube (2) has a further purpose of acting as a finger valve in the axial bore (15) of the piston (14) that extends from the distribution chamber (12) to the second end (16).
- distribution chamber (12) When disengaged from bore (15), distribution chamber (12) will vent through axial bore (15) and exhaust passage (20) and vents (22) in the drill bit (21) and to the atmosphere, as required for the hammer (1) to assume a flushing mode.
- the compressed air supply flow path extends from the check valve (10), into supply passage (11) past an exhaust port (19) and continues into distribution chamber (12).
- the exhaust passage for the drive chamber (18) extends through the exhaust port
- a working surface area (24) in distribution chamber (12) has pressure acting on it throughout the working cycle of the hammer (1) and serves to add to a drive chamber surface area at (13) on the piston (14) when the drive chamber (18) is compressed.
- a further function of surface area (24) is that when the hammer (1) is required to drill at horizontal or at an angle above the horizontal and the piston (14) tends to fall away from the drill bit (21) due to gravity or in the horizontal it sits somewhere between the points (25), (26) and (27) (see Figures 1-4) adjacent undercuts or recesses in the wear sleeve (6), the pressure on surface area (24) will cause the piston (14) to move towards the drill bit (21) and into starting or flushing position.
- Figures 1-2 and Figures 3-4 are respectively of a piston for a tube (or foot valve tube) and another for a tubeless hammer design.
- a drill bit may be supplied complete with a foot valve tube.
- the foot valve tube may be removed.
- the bore in a piston stem for the tubeless design, as shown in Figures 3-4, could optionally be made large enough to fit over the foot valve tube. In that case, it will not be necessary to remove the foot valve tube.
- the arrangement selected may depend on the thickness and strength of the wall required for the piston stem.
- a by-pass passage (10.1) that extends through the check valve (10) with an optional metering plug (10.2) providing an orifice to allow for extra flushing when necessary (see Figure 6).
- the opening to the by-pass passage (10.1) which is fitted with the plug (10.2) is located on the head (33) at a position that is downstream from the valve seat (34).
- the by-pass passage (10.1) exits through the surface (B) on the end of the check valve stem.
- the higher pressure on surface (A) and lower pressure on surface (B) provides unbalanced forces acting on the two ends of the check valve (10) and prevents the check valve (10) from returning to its upward position by counteracting the force of the spring (35), when there is no flow due to the piston (14) shutting the relevant ports.
- Compressed air enters bore (32) in the back-head (7) and opens the check valve (10) off the valve seat (34).
- a flow of air continues past the check valve (10) down the inlet or supply passage (11) of the dual tube and into distribution chamber (12).
- the piston (14) is brought into starting position with the drill bit (21) abutting an annular face of a chuck (37).
- compressed air from distribution chamber (12) flows via distribution ports (36) which extend through the wall of the piston (14), into a return chamber cut out (38).
- the cut-out (38) is defined by precise points (26) and (27).
- the flow continues into return chamber (23) and the pressure build up acts on a surface at the second end (16) to urge the piston (14) in an upward direction.
- the point (29) on the piston passes point (26) in the bore of the wear sleeve (6) and cuts off or stops the flow into return chamber (23).
- the piston (14) gains upward speed and point (28) on the piston (14) will pass point (25) in the bore of the wear sleeve (6) to allow compressed air from distribution chamber (12), via distribution ports (36) to enter drive chamber (18).
- exhaust port (19) has been shut off by the walls of air distribution chamber (12) to provide a sealed environment for drive chamber (18).
- the pressure build up in drive chamber (18) acts on a surface at the first end (13) of the piston (14) and causes it to slow down and commence a reverse direction of travel. Pressure on surface area at the first end (13) combined with existing pressure on surface area (24) accelerate the piston (14) towards the bit (21) to deliver an impact blow.
- the walls of the air distribution chamber (12) uncover exhaust port (19) allowing drive chamber (18) to exhaust down (17), (15), (20) and (22) to atmosphere.
- Point (28) passes point (25) shutting off distribution ports (36) from drive chamber (18).
- the bit (21) has to drop forward with the piston (14) following but in the case of horizontal or upward drilling, the bit (21) cannot fall forward due to gravity so when the hammer (1) is pulled backwards from the hole bottom, the piston (14), powered by surface area (24) in the distribution chamber (12), will push the bit (21) forward to eventually stop against the bit retaining rings (44).
- return chamber (23) should be vented to the atmosphere since if there is no escape for the air trapped in return chamber (23), the piston (14) will hit this body of air, compress it and bounce back into starting position thus preventing the piston (14) from stopping and the hammer (1) from going into flushing mode.
- piston stem bush (52) Figures 3-4) to allow return chamber (23) to vent via the reduced diameters: on the anvil head ( Figures 1-2); and ii. piston stem ( Figures 3-4).
- venting return chamber 23
- Alternative methods and exhaust flow paths may be used.
- the piston is guided and in sliding engagement with the control tube throughout normal reciprocation during the drill cycle.
- the airflow path is very direct to the chambers which increases the energy output and optimises the frequency of the piston.
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Earth Drilling (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ZA2021/07670A ZA202107670B (en) | 2019-03-20 | 2021-10-11 | A drill hammer |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ZA2019/01724 | 2019-03-20 | ||
ZA201901724 | 2019-03-20 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2020188530A2 true WO2020188530A2 (en) | 2020-09-24 |
WO2020188530A3 WO2020188530A3 (en) | 2020-12-03 |
Family
ID=72520563
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB2020/052578 WO2020188530A2 (en) | 2019-03-20 | 2020-03-20 | A drill hammer |
Country Status (2)
Country | Link |
---|---|
WO (1) | WO2020188530A2 (en) |
ZA (1) | ZA202107670B (en) |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AUPQ717100A0 (en) * | 2000-04-28 | 2000-05-18 | Rear, Ian Graeme | Down hole hammer having a top sub |
AU2009202750A1 (en) * | 2008-07-10 | 2010-01-28 | Bernard Lionel Gien | Pneumatic drill |
WO2017118963A1 (en) * | 2016-01-10 | 2017-07-13 | Gien Bernard L | A pneumatic drill hammer |
-
2020
- 2020-03-20 WO PCT/IB2020/052578 patent/WO2020188530A2/en active Application Filing
-
2021
- 2021-10-11 ZA ZA2021/07670A patent/ZA202107670B/en unknown
Also Published As
Publication number | Publication date |
---|---|
WO2020188530A3 (en) | 2020-12-03 |
ZA202107670B (en) | 2022-09-28 |
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