The present invention generally relates to a down-the-hole drill (“DHD”). In particular, the present invention relates to a drive coupling for a DHD hammer.
Typical DHDs include a hammer having a piston that is moved cyclically with high pressure gas (e.g., air). The piston generally has two end surfaces that are exposed to working air volumes (i.e., a return volume and a drive volume) that are filled and exhausted with each cycle of the piston. The return volume pushes the piston away from its impact point on a bit end of the hammer. The drive volume accelerates the piston toward its impact location on the back end of the drill bit. The overall result is a percussive drilling action.
Conventional drill bits, as shown in
In operation of such conventional drill bits, the piston of the DHD hammer (which is driven by working air volumes) percussively impacts the back end 1180 of the shank section 1140 while a chuck (not shown) intermittently engages the splines 1160 on the shank section 1140 to rotationally move the drill bit 1000 about a central axis. The working air volumes are typically exhausted from the DHD hammer through an exhaust tube 1200 at the back end of the shank section 1140. Such impacts upon the back end 1180 of the shank section 1140 take place within the body of the main housing of the DHD hammer. Such impacts also makes the drill bit 1000 susceptible to elastic stress waves, which can lead to ultimate fatigue failure, due in part to the elongated nature of the shank 1140 and the aggressive sectional change between the head 1120 and shank 1140 sections.
The chuck, which is threadedly connected to the DHD hammer casing (not shown), operates to engage the splines 1160 on the shank section 1140 to provide for rotational movement. This movement of the chuck however, results in increased stresses created by the relatively small torque transmission diameter of the shank section 1140 compared to the head section 1120 and because of the high intensity elastic strain wave that passes through this small diameter section. As a result, localized burning and/or galling of the splines 1160 in the area between the head section 1120 and the chuck often results, which can lead to accelerated fatigue failure and then part failure. Moreover, due to the high torque forces applied by the chuck over a relatively small surface area on the splines 1160, the chuck threads can seize upon the DHD hammer. The seized chuck threads can make removal of the chuck and/or drill bit 1000 extremely difficult and costly.
Accordingly, there is a need for a low cost drill bit for DHDs that is not limited by the problems associated with conventional DHD hammers.
Briefly stated, the present invention comprises a down-the-hole drill hammer that includes a cylindrical housing and a piston mounted within the housing along a longitudinal direction. The piston is configured to reciprocatively move within the housing along the longitudinal direction. The down-the-hole drill hammer further includes a drill bit disposed distal to the housing. The drill bit includes a head, a shank extending from the head and a drive coupling operatively engaging the housing and the drill bit.
The following detailed description of the preferred embodiments of the present invention will be better understood when read in conjunction with the appended drawings. For the purposes of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It is understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:
Reference will now be made in detail to the present examples of the invention illustrated in the accompanying drawings. Wherever possible, the same or like reference numbers will be used throughout the drawings to refer to the same or like portions. It should be noted that the drawings are in simplified form and are not drawn to precise scale. In reference to the disclosure herein, for purposes of convenience and clarity only, directional terms such as top, bottom, above, below and diagonal, are used with respect to the accompanying drawings. Such directional terms used in conjunction with the following description of the drawings should not be construed to limit the scope of the invention in any manner not explicitly set forth.
In a preferred embodiment, the present invention provides for a DHD hammer 10, as shown in
The backhead 14 can be any conventional backhead 14 readily used in DHD hammers. The structure and operation of such backheads are readily known in the art and a detailed description of the backhead 14 is not necessary for a complete understanding of the present invention. However, an exemplary backhead 14 suitable for use in the present embodiment is described in U.S. patent application Ser. No. 12/361,263 assigned to Center Rock, Inc. U.S. patent application Ser. No. 12/361,263 is hereby incorporated by reference in its entirety. Torque, thrust, compressed air power and rotation are supplied to the DHD hammer 10 through the backhead pipe connection 15 which connects to the down-the-hole drill. The torque and rotation is further conveyed to the drill bit 24 by the casing 12 itself, which rotates along with the backhead pipe connection 15.
The piston 16 can be any conventional piston readily used in DHD hammers. The structure and operation of such pistons is readily known in the art and a detailed description of the piston 16 is not necessary for a complete understanding of the present invention. However, a piston 16 suitable for use in the present embodiment is described in U.S. patent application Ser. No. 12/361,263. In general, the piston 16 is mounted within the casing 12 along a longitudinal direction and configured to reciprocatively move within the casing 12 along the longitudinal direction.
The drive coupling 17 includes a bearing 20, a plurality of lugs 22 (
The bearing 20, as best shown in
The plurality of lugs 22, as assembled to the DHD hammer 10, are shown in
The shank 44 is also configured with a plurality of lug ports 46. The plurality of lug ports 46 includes three circumferentially spaced lug ports 46 that are configured to receive and engage the three lugs 22a-c, respectively. Each lug port 46 has two opposing drive surfaces 48a, 48b that can engage the corresponding lug drive surfaces 26a, 26b respectively. The drive surfaces 48a, 48b are configured to have a single point contact area that is greater than the single point contact area of conventional shank splines 1160. The single point contact area is defined as the contact area upon which a single lug drive surface (e.g., lug drive surface 26a) engages a lug port 46 drive surface (e.g., drive surface 48a). Preferably, the single point contact area of the drive surfaces 48a, 48b is about 25% greater than conventional single point contact areas of shank splines 1160 and more preferably about 50% greater than conventional single point contact areas of shank splines 1160. The drive surfaces 48a, 48b are also configured to extend radially outwardly further than conventional shank splines 1160. Preferably, the drive surfaces extend further radially outwardly by about 10% or more than conventional shank splines 1160 and more preferably about 25% or more than conventional shank splines 116.
The drive surfaces 48a, 48b are further configured to have a cross-sectional area normal to the central axis of the DHD hammer 10 that is greater than the cross-sectional area of conventional shank splines 1160. Preferably, the cross-sectional area of the drive surfaces 48a, 48b normal to the central axis of the DHD hammer 10 is about 15% greater than for conventional shank splines 1160 and more preferably about 50% greater than conventional shank splines 1160. The drive surfaces 26a, 26b of the lugs 22a-c of the present embodiment advantageously provides for a significantly larger surface area upon which the lugs 22a-c can apply a rotational force compared to the surface area provided for on conventional shank splines 1160, thus reducing the possibility of burning and stresses at the point of contact. Preferably, the overall diameter of the shank 44 is substantially equivalent to the overall diameter of the distal end of the casing 12.
The lug ports 46 each include a radially outwardly extending flange 52 formed about a top end of the shank 44. The plurality of lug ports 46 and flanges 52 are configured to receive the distal flange 40 of the lugs 22a-c, such that the distal flanges 40 of each lug 22 can slide along the longitudinal wall of their respective lug port 46. The flanges 52 also serve in part to secure the drill bit 24 to the rest of the DHD hammer 10.
The drill bit 24, having such a shallow or low-profile, advantageously reduces the amount of stress imparted upon the drill bit 24 as a result of the percussive movement of the piston 16 impacting the drill bit's 24 impact surface 54. That is, due to the reduced profile of the shank 44, the elastic stress waves observed by the shank 44 is reduced. Moreover, as a result of the reduced stresses imparted on the drill bit 24, the drill bit 24 can be manufactured from cylindrical bar stock material, such as a bar stock metal or alloy, and machined rather than forged material and a forging process. This allows for reduced material and manufacturing costs. In addition, the drill bit 24 is completely distal to the casing 12 yet operatively connected to the casing 12.
In sum, the DHD hammer 10 of the present embodiment provides for a drive coupling that can minimize contact pressures on the shank 44 while maximizing the shank's 44 cross-sectional area. In particular, the DHD hammer 10 can provide for a larger diameter shank 44 relative to conventional DHD hammer shank sections (such as shank section 1140), which therefore results in a larger torque moment arm (L) on the shank 44 and a larger shank 44 cross-sectional area. A larger diameter shank 44 can be made possible as a direct result of the lug based drive coupling.
Referring to
In operation, as the piston 16 percussively impacts against the impact surface 54 of the drill bit 24 which is maintained at or below the most distal edge of the casing 12, the drill bit 24 is rotationally moved by the lugs 22a-c engaging the lug ports 46. This advantageously results in less fatigue stress on the shank 44, due to its shallow profile and relatively large drive surface areas, thereby eliminating the problems associated with conventional chucks seizing on shank splines.
In another preferred embodiment, the present invention provides for a DHD hammer 100, as shown in
As best shown in
The bearing 120, as best shown in
The plurality of segmented lugs 122, as assembled to the DHD hammer 100 is best shown in
Like the previous embodiment, the present embodiment advantageously provides for a DHD hammer 100 that experiences less overall stresses, is less susceptible to fatigue failure, and more easily maintenanced. In addition, the present embodiment also advantageously provides for a DHD hammer 100 that is simpler in design and more robust as a result of less overall parts forming the drive coupling 117 of the DHD hammer 100 relative to conventional DHD hammers.
In yet another preferred embodiment, the present invention provides for a DHD hammer 200 as shown in
The drive coupling 217 is configured as a chuck assembly 217′. The chuck assembly 217′ includes a plurality of chuck segments, such as three chuck segments 222a-c, as shown in
The cylindrical chuck 222 includes a proximal end 223 and a distal end 226. The proximal end 223 is configured with a connector 228. Preferably the connector 228 is a threaded connector 228 for threaded engagement with corresponding threads 230 on the distal end of the casing 212. Preferably, the threaded connector 228 is configured along the outside surface of the cylindrical chuck 222 so as to engage corresponding threads 230 configured along an inside surface of the casing 212. The distal end 226 is configured to have an overall outside diameter that is larger than the overall outside diameter formed by the proximal end 223. Preferably, the overall outside diameter of the distal end 226 is substantially the same or greater than the overall outside diameter of the distal end of the casing 212. As a result, the distal end 226 of the cylindrical chuck 222 is completely distal to the casing 212.
Referring to
The distal end 226 of the chuck segment 222a also includes a plurality of chuck splines 232 that extend radially inwardly. Each of the plurality of chuck splines 232 is configured to engage one of a plurality of shank splines 236, further described below. In between each of the plurality of chuck splines 232 is a groove 234 configured to receive a shank spline 236. About a distal end of each of the chuck splines 232 is an inwardly extending flange portion 238. Each of the inwardly extending flange portions 238 extends radially inwardly so as to engage an outwardly extending flange portion 240 (
Within the distal end 226 of the cylindrical chuck 222 is a radially inwardly extending flange 258. The flange 258 operatively engages a thrust surface 256 on a rearwardly facing surface of the shank 244, as further described below. When assembled into the cylindrical chuck 222, the flange 258 forms a substantially circular flange surface that correspondingly engages the thrust surface 256. This advantageously provides for the thrust surface 256 to be completely housed by and protected by the chuck assembly 217′.
Forming the cylindrical chuck 222 out of individual chuck segments advantageously allows for the cylindrical chuck 222 to integrally form the inwardly extending flange portions 238 directly on the chuck segments 222a-c. That is, the inwardly extending flange portions 238 is an integrally formed drill bit retaining mechanism. Therefore, the chuck segments 222a-c can be assembled around the drill bit 224 rather then the drill bit 224 having to be axially incorporated into the drive coupling 217. This eliminates additional parts and the complexities associated with axially incorporated drill bits to drive couplings in conventional DHD hammers.
The chuck assembly 217′ also includes a bearing 220, as best shown in
The chuck assembly 217′ can optionally include a thrust washer 218 that circumscribes the cylindrical chuck 222. In an assembled state, the thrust washer 218 is situated to mount on the distal end 226 of the cylindrical chuck 222, as shown in
Referring to
The shank 244 is a low-profile shank. That is, the longitudinal length of the shank 244 extending along axis-C is shorter in length compared to conventional drill bit shanks. Preferably, the shank 244 is less than about 200% of the longitudinal length of the head 242 and more preferably, less than about 100% of the longitudinal length of the head 242.
The shank 244 includes a plurality of shank splines 236 circumferentially spaced about the shank 244. In between each of the plurality of shank splines 236 is a groove 247 configured to receive a chuck spline 232. The plurality of chuck splines 232 and shank splines 236 are configured to operatively engage each other as shown in
Referring to
Preferably, the shank 244 and cylindrical chuck 222 are each configured with nine splines. It has been discovered that nine corresponding splines advantageously allows for the cylindrical chuck 222 and shank 244 to be configured with the greatest amount of torque without significantly impacting galling. However, the number of splines for the shank 244 and cylindrical chuck 222 can be more or less than nine depending upon the overall size of the DHD Hammer 200.
About the proximal end of the shank 244 is the outwardly extending flange portion 240. The outwardly extending flange portion 240 extends radially outwardly beyond the groove's 247 longitudinal surface, but not past the outer radial edges of the shank splines 236. The outwardly extending flange portion 240 is also integrally formed with the drill bit's thrust surface 256. The thrust surface 256 is normal to the longitudinal direction of the drill bit 244 and configured as a generally circular ring-shaped thrust surface 256.
Concentric with the thrust surface 256 is the drill bit's impact surface 254. The impact surface 254 is slightly raised relative to the plane of the thrust surface 256. The impact surface 254 is configured to receive the percussive impact forces of the piston 216.
As best shown in
Because the distal end 226 of the cylindrical chuck 222 is distal to the casing 212, the overall diameter of the distal end 226 can advantageously be made larger. That is, since the distal end 226 is not located within the casing 212, the overall dimensions of the distal end 226 is not restricted by the internal dimensions of the casing 212. As a result, since the distal end 226 can be made larger, the overall diameter of the shank 244 can be made larger. This is advantageous since a larger shank diameter allows for larger torque. In addition, the overall diameter of each of the shank splines 236 is greater than the bore diameter of the casing 212. Alternatively, the overall diameter of the shank splines 236 can be made equal to the bore diameter of the casing 212.
The DHD hammer 200 can also optionally include a seal 260, as shown in
Similar to the above embodiments, the present embodiment advantageously provides for a drive coupling 217 that minimizes contact pressures and maximizes torque on the drill bit 224. This is accomplished by providing a shank with a lower profile and larger diameter relative to conventional DHD hammers. These advantages are distinctly provided for by positioning the drill bit 224 distal to the casing 212. Additionally, the cylindrical chuck 222 can be radially assembled onto the drill bit 224, which therefore allows for an integrally formed drill bit retaining mechanism on the drive coupling 217 to maintain the drill bit 224 onto the DHD hammer 200 while maintaining the drill bit 224 distal to the casing 212.
In sum, the DHD hammer 200 of the present embodiment provides for a drive coupling assembly that minimizes contact pressures on the shank 244 while maximizing the shank's 244 cross-sectional area. This is accomplished by providing a larger diameter shank 244 relative to conventional DHD hammer shank sections (such as shank section 1140), which therefore results in a longer torque moment arm (L) on the shank 244 and a larger shank 244 cross-sectional area (Areashank). A larger diameter shank 244 is made possible as a direct result of the lug based drive coupling. This benefit can be expressed as a ratio (R) of the shank cross-sectional sectional area (Areashank), torque contact area (Areacontact), and torque moment arm (L) relative to the applied torque (T) as defined by Ratio 1 below.
As defined by Ratio 1, the present embodiment can provide for a DHD hammer having a ratio R that is increased up to about 28% or more.
It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.
This application is a Section 371 of International Application No. PCT/US2009/308957, filed Mar. 31, 2009, which was published in the English language on Oct. 8, 2008 under International Publication No. WO 2009/124051 A3, which claims the benefit of priority pursuant to 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/040,817, filed Mar. 31, 2008, the disclosures of which are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/US2009/038957 | 3/31/2009 | WO | 00 | 10/14/2010 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2009/124051 | 10/8/2009 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
1330736 | Church | Feb 1920 | A |
1815660 | Walker | Jul 1931 | A |
2038602 | Redinger | Apr 1936 | A |
2379472 | Bowman | Jul 1945 | A |
2710740 | Dempsey | Jun 1955 | A |
3893521 | Bailey et al. | Jul 1975 | A |
3991834 | Curington | Nov 1976 | A |
4050525 | Kita | Sep 1977 | A |
4085809 | Lovell et al. | Apr 1978 | A |
4333537 | Harris et al. | Jun 1982 | A |
4530408 | Toutant | Jul 1985 | A |
4691779 | McMahan et al. | Sep 1987 | A |
4765418 | Ennis | Aug 1988 | A |
4819739 | Fuller | Apr 1989 | A |
4878550 | Chuang | Nov 1989 | A |
4919221 | Pascale | Apr 1990 | A |
5065827 | Meyers et al. | Nov 1991 | A |
5085284 | Fu | Feb 1992 | A |
5301761 | Fu et al. | Apr 1994 | A |
5305837 | Johns et al. | Apr 1994 | A |
5322136 | Bui et al. | Jun 1994 | A |
5322139 | Rose et al. | Jun 1994 | A |
5398772 | Edlund | Mar 1995 | A |
5794516 | Wolfer et al. | Aug 1998 | A |
5915483 | Gien | Jun 1999 | A |
5984021 | Pascale | Nov 1999 | A |
RE36848 | Bui et al. | Sep 2000 | E |
6125952 | Beccu et al. | Oct 2000 | A |
6131672 | Beccu et al. | Oct 2000 | A |
6135216 | Lyon et al. | Oct 2000 | A |
6170581 | Lay | Jan 2001 | B1 |
6237704 | Lay | May 2001 | B1 |
6263969 | Stoesz et al. | Jul 2001 | B1 |
D454143 | Åsberg | Mar 2002 | S |
6502650 | Beccu | Jan 2003 | B1 |
6637520 | Purcell | Oct 2003 | B1 |
6698537 | Pascale et al. | Mar 2004 | B2 |
6708784 | Borg | Mar 2004 | B1 |
7017682 | Chan et al. | Mar 2006 | B2 |
7117939 | Hawley et al. | Oct 2006 | B1 |
7159676 | Lyon | Jan 2007 | B2 |
7163058 | Bakke et al. | Jan 2007 | B2 |
7198120 | Gien | Apr 2007 | B2 |
7389833 | Walker et al. | Jun 2008 | B2 |
7467675 | Lay | Dec 2008 | B2 |
7617889 | Beccu | Nov 2009 | B2 |
8312944 | Marshall et al. | Nov 2012 | B2 |
20030102167 | Pascale et al. | Jun 2003 | A1 |
20040188146 | Egerstrom | Sep 2004 | A1 |
20060225885 | Mcgarian et al. | Oct 2006 | A1 |
20060249309 | Cruz | Nov 2006 | A1 |
20070039761 | Cruz | Feb 2007 | A1 |
20070102196 | Bassinger | May 2007 | A1 |
20080087473 | Hall et al. | Apr 2008 | A1 |
20080156539 | Ziegenfuss | Jul 2008 | A1 |
20090294180 | Swadi et al. | Dec 2009 | A1 |
20100059284 | Lyon et al. | Mar 2010 | A1 |
20100089649 | Welch et al. | Apr 2010 | A1 |
20100243333 | Purcell | Sep 2010 | A1 |
20100252330 | Gilbert et al. | Oct 2010 | A1 |
20110303464 | Mulligan | Dec 2011 | A1 |
20120118648 | Lorger | May 2012 | A1 |
Number | Date | Country |
---|---|---|
1910640 | Apr 2008 | EP |
10-2006-0106388 | Oct 2006 | KR |
2007010513 | Jan 2007 | WO |
2007077547 | Jul 2007 | WO |
2009124051 | Oct 2009 | WO |
2010082889 | Jul 2010 | WO |
Entry |
---|
Office Action issued Dec. 23, 2011 in U.S. Appl. No. 12/621,155. |
Office Action issued Jan. 19, 2012 in U.S. Appl. No. 12/361,263. |
Office Action issued Feb. 1, 2012 in AU Application No. 2009231791. |
Office Action issued Sep. 15, 2011 in AU Application No. 2009231791. |
Written Opinion Issued Feb. 22, 2011 in Int'l Application No. PCT/US2010/021011, 4 pages. |
Office Action Issued Apr. 11, 2011 in U.S. Appl. No. 12/621,155. |
Office Action issued Jun. 30, 2011 in SE Application No. 1051069-1. |
Office Action issued Oct. 18, 2011 in U.S. Appl. No. 12/621,155. |
Office Action issued Nov. 29, 2012 in U.S. Appl. No. 12/621,155. |
Office Action issued Nov. 8, 2012 in Canadian Application No. 2,750,810. |
Examination Report issued Dec. 7, 2012 in Australian Application No. 2010208528. |
Office Action issued Feb. 7, 2012 in Chilean Patent Application No. 1015/2010. |
International Preliminary Report on Patentability issued Mar. 13, 2012 in International Application No. PCT/US2010/021011. |
Office Action issued May 17, 2011 in U.S. Appl. No. 12/361,263. |
Int'l Search Report issued May 31, 2011 in Int'l Application No. PCT/US2010/056917; Written Opinion. |
International Preliminary Report on Patentability issued on Oct. 5, 2010 in International Application No. PCT/US2009/038957. |
Office Action Issued Dec. 7, 2010 in U.S. Appl. No. 12/361,263. |
Office Action issued May 10, 2012 in U.S. Appl. No. 12/361,263. |
Office Action issued Jun. 7, 2012 in U.S. Appl. No. 12/621,155. |
Office Action issued Jun. 4, 2012 in Canadian App. No. 2,718,669. |
Office Action issued May 14, 2012 in Swedish App. No. 1150769-6. |
Office Action issued Jun. 21, 2012 in Swedish App. No. 1150985-8. |
Int'l Search Report and Written Opinion issued on May 26, 2009 in Int'l Application No. PCT/US2009/038957. |
Int'l Search Report and Written Opinion Issued Mar. 19, 2010 in Int'l Application No. PCT/US2010/021011. |
Office Action Issued Jun. 24, 2010 in U.S. Appl. No. 12/361,263. |
Office Action issued May 31, 2013 in Australian Application No. 2011235927. |
Office Action issued May 7, 2013 in Chilean Application No. 1785-2011. |
Office Action issued Mar. 13, 2013 in U.S. Appl. No. 12/909,495. |
Office Action issued Mar. 22, 2013 in Swedish Application No. 1250524-4. |
Office Action issued Apr. 17, 2013 in Swedish Application No. 1051069-1. |
Office Action issued Apr. 15, 2013 in Korean Application No. 10-2011-7019644. |
Office Action issued May 28, 2013 in U.S. Appl. No. 12/621,155. |
Office Action issued May 9, 2013 in Canadian Application No. 2,755,592. |
Office Action issued May 10, 2013 in Canadian Application No. 2,750,810. |
Office Action issued Aug. 26, 2013 in U.S. Appl. No. 12/909,495. |
Office Action issued Oct. 24, 2013 in Korean Patent Application No. 2012-7015756. |
Office Action issued Apr. 28, 2014 in Korean Patent Application No. 2012-7015756. |
Number | Date | Country | |
---|---|---|---|
20110036636 A1 | Feb 2011 | US |
Number | Date | Country | |
---|---|---|---|
61040817 | Mar 2008 | US |