CA1264318A - Drill bit - Google Patents
Drill bitInfo
- Publication number
- CA1264318A CA1264318A CA000525593A CA525593A CA1264318A CA 1264318 A CA1264318 A CA 1264318A CA 000525593 A CA000525593 A CA 000525593A CA 525593 A CA525593 A CA 525593A CA 1264318 A CA1264318 A CA 1264318A
- Authority
- CA
- Canada
- Prior art keywords
- lubricant
- body portion
- flow
- gaseous fluid
- conduit means
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000000314 lubricant Substances 0.000 claims abstract description 96
- 239000012530 fluid Substances 0.000 claims abstract description 67
- 238000005553 drilling Methods 0.000 claims abstract description 52
- 238000005520 cutting process Methods 0.000 claims abstract description 46
- 238000004891 communication Methods 0.000 claims description 3
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims 2
- 230000001276 controlling effect Effects 0.000 claims 1
- 239000000203 mixture Substances 0.000 abstract description 8
- 230000015572 biosynthetic process Effects 0.000 abstract description 4
- 238000005755 formation reaction Methods 0.000 abstract description 4
- 238000001816 cooling Methods 0.000 description 5
- 238000005461 lubrication Methods 0.000 description 5
- 239000000428 dust Substances 0.000 description 3
- 238000010410 dusting Methods 0.000 description 3
- 210000002445 nipple Anatomy 0.000 description 3
- 239000003921 oil Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000010687 lubricating oil Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 101150035006 UBA3 gene Proteins 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000007789 sealing 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
- E21B10/00—Drill bits
- E21B10/08—Roller bits
- E21B10/22—Roller bits characterised by bearing, lubrication or sealing details
- E21B10/24—Roller bits characterised by bearing, lubrication or sealing details characterised by lubricating details
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
ABSTRACT OF THE DISCLOSURE
A drill bit for drilling into underground formations is disclosed, the drill bit having one or more first conduits for supplying gaseous drilling fluid to the cutting cone bearings, one or more second conduits for supplying lubricant to the cutting cone bearings, which conduits combine the gaseous drilling fluid with the lubricant in order to supply a mixture of gaseous fluid and lubricant to the bearings.
A drill bit for drilling into underground formations is disclosed, the drill bit having one or more first conduits for supplying gaseous drilling fluid to the cutting cone bearings, one or more second conduits for supplying lubricant to the cutting cone bearings, which conduits combine the gaseous drilling fluid with the lubricant in order to supply a mixture of gaseous fluid and lubricant to the bearings.
Description
12~4318 IMPROVED DRILL BIT
FIELD OF THE INVENTION
The present invention relates to a drill bit for drilling into earth formations, and more particularly to a drill bit having means for providing a controlled flow of lubricant or combining liquid lubricant with gaseous drilling fluid to ~upply a lubricant and ga~eous fluid mixture to the cutting cones for lubrication and cooling of the cutting cone bearings.
DESCRIPTION OF THE PRIOR ART
Typical drill bits are used in combination with, for example, a rotary drill pipe system, for drilling deep holes into underground formations, such as into rock, coal, or the like. In a drilling system of this type, a drill string is formed by connecting a number of hollow extension pipes through which a drilling fluid, which may be either a drilling mud or a gaseous drilling fluid such as air, is supplied by way of the extensions to the drill bit to be exhausted at the surface being drilled. The drill bit contains suitable openings, such as nozzles, for discharging the drilling fluid from the drill bit onto the surface being drilled to clear dust and cuttings and scavenge them away from the area of the cutting cones. The drill bit of the present invention is for use in connection with drilling systems using a gaseous drilling fluid.
i2~;4;~18 In the above-de~cribed ~y~tem, a 3ubas~emb1y may be located on the drill string between the drill bit and the extension pipe line. A ~ubassembly structure i~ known in the art and generally includes a central conduit, or plenum chamber, which extends from the rotary drill extension pipe to the vicinity of the drill bit. Pressurized air or other gasous drilling fluid from the rotary drill flows through the plenum chamber and is discharged downwardly through the drill bit, either through a central opening, or through nozzles positioned between the cutting cones.
A source of major concern in the drilling art is protection of the cutting cones from excess wear and heat. It is desirable to lubricate or cool the cutting cone bearings and shafts which increases the useful life of the cutting cones and avoids the necessity of frequent drill bit replacement during a drilling operation. In the prior art, various systems have been employed to supply lubricant to the cutting cone bearings for lubrication during operation. In these systems, lubricant may be supplied from a storage means which i9 located either in the subassembly structure or in the drill bit itself. For example, in U.S. Patent No. 3,029,881, a system is disclosed wherein a lubricant storage means is provided in the subassembly.
The pressure of the gaseous fluid in the subassembly plenum chamber acts upon an expandable liner to force lubricant from the storage means, and into a lubricant supply conduit provided in the subassembly. The subas~embly conduit communicates with a drill bit :12~318 conduit to supply lubricant to the bearings. A majoc disadvantage which may arise in this system is that lubricant accumulates in the area of the bearing~, and may brea~ down due to the heat of the cutting cones.
S It iR desirable, therefore, to provide means to continually flush lubricant from the bearings hefore such breakdown occurs.
Another approach in the prior art has been to u~e the ga~eous drilling fluid it~elf to cool the utting cone bearings. For example, in U.S. Patent No.
4,080,091, a drill bit is disclosed which provides a conduit communicating between the hollow interior of the drill bit and the cutting cone bearings, to allow passage of drilling air to the bearings. In this lS arrangement, relatively cool drilling air is intro-duced to cool the cutting cone bearings and shafts, as they become heated during the drilling operation.
U. S. Patent No. 3,125,175 also discloses a structure which provides a conduit communicating between the hollow interior of the drill bit and the cutting cone bearings. In this structure, a ring member is provided in the drill bit, which reduces the quantity of air which enters the conduit, as compared to the quantity of air which exits in the vicinity of the cutting cones. Both of these systems suffer from the disadvantage that, although the bearings are cooled, they are not lubricated.
U. S. Patent No. 2, 814,464 discloses a drill bit structure provide a conduit between the drill bit interior and the cutting cone bearings, and sugge3ts ~26~1~18 that the drilling fluid may consist of an air stream containing a fine ~pray of lubricant such a~ oil, to lubricate the cutting cone bearings. Of course, when oil is injected into the drilling air, oil is also contained in the air which exits at the drilling surface in the vicinity of the cutting cones. This is unde3irable since it results in oiling the drilling surface and oiling of the dust and cuttings arising from the drilling operation.
Another gaseous fluid drilling system employing lubricant entrained in the gaseous drilling fluid is diqclosed in U. S. Patent No. 3,924,695. The drill bit structure disclosed includes a separator assembly, which acts to remove lubricant from the gaseous drilling fluid beore it is discharged onto the drilling surface. The lubricant, removed from the gaseous stream i3 then directed to the cutting cone bearings by way of a conduit provided in the drill bit.
A drill bit ~tructure providing for an internal storage source of liquid lubricant is di~closed in U.S.
Patent No. 4,375,242. In the drill bit, an air conduit i~ provided between the drill bit interior and a sealing o-ring, which supports the cutting cone on the bit. The pre~sure from the air conduit also acts to urge lubricant from the internal storage ~ource, and supply the lubricant by way of a separate conduit to the cutting cone bearings for lubrication.
With the foregoing in mind, it is an object of the present invention to provide for an improved drill lZ~
bit ~tructure which enables lubricant, which ~ay be supplied, for example, from a storage means in a drill subassembly, to be combined with gaseou~ drilling fluid in a conduit means which communicate~ between the interior of the drill bit and the cutting cone bearing~. A ga~eous fluid and lubricant mixture or at the normal operating pressure, lubricant is supplied through the conduit means at a controlled rate to the cutting cone bearings to provide both cooling and lubrication.
SUMMARY OF THE INVENTION
The present invention provides for a drill bit for use in a rotary drill system utilizing a source of gaseou~ fluid under pressure. The drill bi~ is lS provided with at least one rotary cutting cone for drilling into an earth formation, such as rock or coal.
The bit is provided with a first conduit means, in the form of an air passage which extends from the hollow interior of the drill bit to the cutting cone bearings.
A second conduit means i~ provided in the drill bit for receiving lubricant from an external storage source, which may be contained in a drilling subassembly. The second conduit means is in the form of a lubricant passage which intersects with and provides lubricant to the first conduit means, whereby a lubricant and gaseous fluid mixture may be formed beyond the intersection. The resulting mixture or lubricant flow is directed, through the first conduit means, to the cutting cone~ for cooling and lubrication of the cutting cone shafts and bearings. Additionally, the second conduit means may contain replaceable orifice elements which regulate the amount of lubricant _5_ 12~431~
entering the second conduit mean~ for combining with the ga3eous fluid in the fir~t conduit mean~.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a cut-away perspective view of a drill bit of the pre3ent invention:
Figure 2 i9 cro~s-sectional view taken acro~
line 2-2 in Figure l; and Figure 3 iY a cross-~ectional view of a drill bit of the present invention attached to a subassembly having an internal storage supply of lubricant.
DE.SCRIPTION OF Tl~E INVENTION
The drill bit of the present invention i3 intended to be attached to a drill string or drilling subassembly, the drill string or ~uba3sembly having a lubricant 3torage means and means for supplying the lubricant to the drill bit.
The drill bit of the present invention comprise~
a main body portion 10 as shown in Figure 1. An upper nipple 11 attaches the drill bit to a drilling subassembly, or to the extension pipe~ forming a drill string. The nipple of the drill bit i9 threaded, 80 as to threadedly engage the tapered socket of a subas~embly and form a firm connection therebetween.
One or more leg portions 12 extend downwardly from the body portion 10 of the drill bit at circumferencially spaced intervals. Mounted for rotation in each leg portion 12 is a rotary cutter 13. It is generally preferred in the industry to use a drill bit having three cutting cone~. Cutting cones 13 are rotatably mounted to the leg portion of the drill bit by bearings 14 and bearing ~haft~ 15.
Th~ dcill bit contain~ a hollow interior portion 16 forming a chamber for receiving ga~eous drilling fluid from the ~uba3~embly plenum chamber. The gaseou3 drilling fluid from chamber 16 i~ exhausted from the drill bit into the area of the cutting cone~ to pick up and remove the dust and cuttings which result from the drilling operation. l'he gaseous drilling fluid may be ejected through nozzles 17 located between the cutting cone~. Alternatively, the nozzle~ may be omitted and the gaaeou~ f1uid ejected through a central orifice located between the cutting cones, as i~ known in the art. In the present ca~e, the orifice must have sufficient restriction to provide an elevated pre3qure lS within the chamber 16.
Communicating between chamber 16 and the cutting cone bearings 14 and bearing shaft~ 15, i9 firqt conduit means 18 forming passage for the ga~eou~
drilling fluid. First conduit means 18 allows gaseous drilling fluid, ~uch as air, to pa~s from the hollow interior of the drill bit through the fir~t conduit mean~ to cool the cutting cone bearings 14 and bearing shafts 15.
The drill bit of the preqent invention is also provided with a circumferential groove 20 surrounding the drill bit, to form a reservoir for lubricant which is located in the qurface of the drill bit surrounding the nipple 11. The circumferential groove, which preferably is approximately 3/16" wide by 3/i6~ deep, receives lubricant from, for example, a supply conduit 126~311~
34 in a drilling subassembly, a~ described hereinafter in connection with Fig. 3. Second conduit means or bore 19 connect~ circumferential groove 20 with fi~st conduit means 18, and supplie~ lubricant from the groove 20 to the gaseous drilling fluid pa~sing through the fir~t conduit means 18 to the bearings. The precise point where second conduit means 19 intersects with first conduit means 18 i~ a choice of design.
In one mode of operation, the lubricant supplied by second conduit means or bore 19 i9 picked up and combined with the gaseous drilling fluid in fir~t conduit means 18, and is supplied to the cutting cone bearings 14. In this manner, a mixture of lubricant and gaseous drilling fluid is supplied to the bearing~
to achieve both a lubricating and a cooling effect.
Also, lubricant build-up and heat breakdown at the bearings i9 avoided due to the continuous supply of fresh mixture provided to the bearings, the air in the mixture acting to flush out lubricant before it ~0 accumulates.
Means is provided to regulate the amount of lubricant supplied to the bearings. To this end, second conduit means 19 may be fitted with replaceable orifices, in the present instance annular rings 21.
Z5 The diameter of the orifice in annular rings 21 may be varied to regulate the flow of lubricant supplied to the bearings. The annular rings 21 may be formed of metal, plastic, or any suitable material. The annular rings 21 are inserted into second conduit means 19 in ~0 the vicinity of circumferential groove 20, for e~ample in a counter bore 22 at the mouth of the bore 19. When 1~i431~
it i8 de~ired to modify the rate at which lubricant i~
~upplied to the bearingR, the user simply remove~ the drill bit from the ~uba~sembly, and replace~ annular ring 21 with an annular ring having a different ~ized orifice, to provide the de~ired lubricant flow.
Referring to Figure 3, the drill bit of the pre~ent invention i9 ~hown attached to a drilling ~uba~sembly. The drill bit of the pre~ent invention i~
de~igned to work in combination with a ~uba~embly having a supply of lubricant contained therein.
, ..........
-- - - A ~ubas~embly having lubricant ~torage i~ ~hown in U. S. Patent No.
3,029,881.
A repre~entative subassembly comprise~ a housing 30 and a hollow plenum chamber 31. Ga~eou~
drilling fluid from the drill line is ~upplied to plenum chamber 31, and then to drill bit interior chamber 16. The ~uba~embly ~tructure additionally contains lubricant ~torage mean~ in the form of, for example, annular chamber 32 surrounding the tlou~ing.
The flow of lubricant from the storage means may be effected in various way~. For example, a passageway 35 may be provided to allow communication between the pressurized gaseou3 fluid in the plenum chamber and the lubricant ~torage area, to act as a pressure ~ource forcing lubricant downward and into lubricant ~upply conduits 34, at spaced intervals around the circumference of the subassembly. A piston (not shown) may be provided in the annular chamber 32 to force lubricant from the chamber. It should be _g_ :IZ~318 apparent that other types of pres3ure means are equally suitable to force lubricant from the 3torage mean3, for example, an expandable liner.
The lubricant forced through supply conduit 34 accumulate~ in the circumferential groove 20 on the drill bit. In the preferred embodiment, illu~trated in Figure 2, the circumEerential groove extends entirely around the drill bit. This obviates the need to align supply conduit(s) 34 on the subassembly with individual bores or second conduit means 19 in the drill bit in order to supply lubricant to the second conduit means.
It ha~ been found beneficial to the operation of the present invention for an orifice ring 36 to be placed in the plenum chamber of the ~ubassembly in order to somewhat reduce the flow of gaseous fluid.
The orifice should be located downstream from the pressure means acting on the lubricant storage in the suba~embly, and upstream of the entrance to first conduit means 18 in the hollow interior chamber 16 of the drill bit. By varying the pressure as controlled by orific ring 36, the flow of lubricant to the bearings can be varied or controlled. In this manner, a greater pre~sure of gaseous fluid is acting upon the lubricant storage means, while a ~omewhat reduced pressure acts upon the first conduit means 18.
Sufficient force to achieve continuous lubricant flow from the chamber 32 is thereby maintained. One expedient arrangement is to place an orifice ring directly at the connection between the subassembly and the drill string below passageway 35. This allows the orifice ring to be removed or replaced ~imply by removing the suba~embly from the drill string.
i2~;~3~L~
Instead of receiving lubricant from a supply conduit in a subas~embly, the drill bit of the present invention may receive lubricant that is supplied by a conduit in the drill string from a surface-mounted supply, as sl)own in u.S. Patent No. 4,508,183. In this arrangement, the drill bit may be attached directly to the extension pipe, and the circumferential groove 20 may receive lubricant directly from the drill string conduit.
In actual operation of the aforesaid structure, it has been found that, at the operating pressures for the gaseous drilling fluid commonly employed in the drill string, the flow to the bearings through first conduit 18 is substantially entirely lubricant. The 1~ flow of lubricant to the bearings and the exclusion of any significant amount of gaseous fluid i3 believed to result from the generally higher pressure in pa~ageway 35 delivering the lubricant to conduit 18, than the flow of gaseous fluid after it has passed through orifice ring 36. As noted previou~ly, orifice ring 36 increases the back pressure above the orifice ring 36 and reduces the quantity of flow of ga3eous fluid in plenum chamber 31. ~lence, a greater pressure iq exerted upon the lubricant storage means 32 by way of ~upply conduit 35, than is present in the plenum chamber 31 and hollow bit interior 16 after the gaseous fluid has passed through orifice ring 36, which results in a lesser pressure gaseous fluid flow inside plenum chamber 31 and in hollow drill bit interior 16.
Accordingly, at the intersection between first conduit 18 and second conduit 19 in the drill bit, the gaseous fluid from the bit interior portion 16 is substantially lZ6~318 - excluded from the lower portion oE conduit 18 at the intersection of conduit 19. ~lence, the flow reaching the cutting cone bearings, through the lower portion of first conduit mean~ 18, i9 substantially entirely lubricant received at a higher pres~ure from conduit 19, with the general re~ult that no subatantial amount of gaseous fluid reache~ the bearings during normal operation. It has been found most beneficial to have the pressurized lubricant metered to the bearings in a controlled manner. ~9 noted earlier, the pressure for the lubricant flow can be controlled by varying the size of the orifice ring 36. In the preferred operation of the system, a limited quantity of lubricant i9 provided for packing the bearing~, without having an excess lubricant flow from the bearing3 into the drill hole which may permit cuttings to float back to the bearing holders and bearings.
It should also be appreciated that, in the preferred operation of the system, when the flow of lubricant of the present system is depleted, the flow of gaseous fluid acting on conduit means 18 will be such that a flow of gaseous fluid is provided to the bearings. Accordingly, in the event the supply of lubricant in ~torage means 32 is exhausted or interrupted, the bearings are nonetheless given some degree of protection by the cooling effect of gaseous fluid supplied to the bearings by first conduit means 18 until such time as the lubricant supply is replenished or reestablished.
In a preferred embodiment of the present invention, a perforated member 40 in the form of a slotted tube is fitted into the mouth of the first lZ6~3~
conduit 18 and act~ to filter dirt, ~tone, or other heavy material which may be pre3ent in the gaqeous drilling fluid from entering the fir~t conduit means 18.
FIELD OF THE INVENTION
The present invention relates to a drill bit for drilling into earth formations, and more particularly to a drill bit having means for providing a controlled flow of lubricant or combining liquid lubricant with gaseous drilling fluid to ~upply a lubricant and ga~eous fluid mixture to the cutting cones for lubrication and cooling of the cutting cone bearings.
DESCRIPTION OF THE PRIOR ART
Typical drill bits are used in combination with, for example, a rotary drill pipe system, for drilling deep holes into underground formations, such as into rock, coal, or the like. In a drilling system of this type, a drill string is formed by connecting a number of hollow extension pipes through which a drilling fluid, which may be either a drilling mud or a gaseous drilling fluid such as air, is supplied by way of the extensions to the drill bit to be exhausted at the surface being drilled. The drill bit contains suitable openings, such as nozzles, for discharging the drilling fluid from the drill bit onto the surface being drilled to clear dust and cuttings and scavenge them away from the area of the cutting cones. The drill bit of the present invention is for use in connection with drilling systems using a gaseous drilling fluid.
i2~;4;~18 In the above-de~cribed ~y~tem, a 3ubas~emb1y may be located on the drill string between the drill bit and the extension pipe line. A ~ubassembly structure i~ known in the art and generally includes a central conduit, or plenum chamber, which extends from the rotary drill extension pipe to the vicinity of the drill bit. Pressurized air or other gasous drilling fluid from the rotary drill flows through the plenum chamber and is discharged downwardly through the drill bit, either through a central opening, or through nozzles positioned between the cutting cones.
A source of major concern in the drilling art is protection of the cutting cones from excess wear and heat. It is desirable to lubricate or cool the cutting cone bearings and shafts which increases the useful life of the cutting cones and avoids the necessity of frequent drill bit replacement during a drilling operation. In the prior art, various systems have been employed to supply lubricant to the cutting cone bearings for lubrication during operation. In these systems, lubricant may be supplied from a storage means which i9 located either in the subassembly structure or in the drill bit itself. For example, in U.S. Patent No. 3,029,881, a system is disclosed wherein a lubricant storage means is provided in the subassembly.
The pressure of the gaseous fluid in the subassembly plenum chamber acts upon an expandable liner to force lubricant from the storage means, and into a lubricant supply conduit provided in the subassembly. The subas~embly conduit communicates with a drill bit :12~318 conduit to supply lubricant to the bearings. A majoc disadvantage which may arise in this system is that lubricant accumulates in the area of the bearing~, and may brea~ down due to the heat of the cutting cones.
S It iR desirable, therefore, to provide means to continually flush lubricant from the bearings hefore such breakdown occurs.
Another approach in the prior art has been to u~e the ga~eous drilling fluid it~elf to cool the utting cone bearings. For example, in U.S. Patent No.
4,080,091, a drill bit is disclosed which provides a conduit communicating between the hollow interior of the drill bit and the cutting cone bearings, to allow passage of drilling air to the bearings. In this lS arrangement, relatively cool drilling air is intro-duced to cool the cutting cone bearings and shafts, as they become heated during the drilling operation.
U. S. Patent No. 3,125,175 also discloses a structure which provides a conduit communicating between the hollow interior of the drill bit and the cutting cone bearings. In this structure, a ring member is provided in the drill bit, which reduces the quantity of air which enters the conduit, as compared to the quantity of air which exits in the vicinity of the cutting cones. Both of these systems suffer from the disadvantage that, although the bearings are cooled, they are not lubricated.
U. S. Patent No. 2, 814,464 discloses a drill bit structure provide a conduit between the drill bit interior and the cutting cone bearings, and sugge3ts ~26~1~18 that the drilling fluid may consist of an air stream containing a fine ~pray of lubricant such a~ oil, to lubricate the cutting cone bearings. Of course, when oil is injected into the drilling air, oil is also contained in the air which exits at the drilling surface in the vicinity of the cutting cones. This is unde3irable since it results in oiling the drilling surface and oiling of the dust and cuttings arising from the drilling operation.
Another gaseous fluid drilling system employing lubricant entrained in the gaseous drilling fluid is diqclosed in U. S. Patent No. 3,924,695. The drill bit structure disclosed includes a separator assembly, which acts to remove lubricant from the gaseous drilling fluid beore it is discharged onto the drilling surface. The lubricant, removed from the gaseous stream i3 then directed to the cutting cone bearings by way of a conduit provided in the drill bit.
A drill bit ~tructure providing for an internal storage source of liquid lubricant is di~closed in U.S.
Patent No. 4,375,242. In the drill bit, an air conduit i~ provided between the drill bit interior and a sealing o-ring, which supports the cutting cone on the bit. The pre~sure from the air conduit also acts to urge lubricant from the internal storage ~ource, and supply the lubricant by way of a separate conduit to the cutting cone bearings for lubrication.
With the foregoing in mind, it is an object of the present invention to provide for an improved drill lZ~
bit ~tructure which enables lubricant, which ~ay be supplied, for example, from a storage means in a drill subassembly, to be combined with gaseou~ drilling fluid in a conduit means which communicate~ between the interior of the drill bit and the cutting cone bearing~. A ga~eous fluid and lubricant mixture or at the normal operating pressure, lubricant is supplied through the conduit means at a controlled rate to the cutting cone bearings to provide both cooling and lubrication.
SUMMARY OF THE INVENTION
The present invention provides for a drill bit for use in a rotary drill system utilizing a source of gaseou~ fluid under pressure. The drill bi~ is lS provided with at least one rotary cutting cone for drilling into an earth formation, such as rock or coal.
The bit is provided with a first conduit means, in the form of an air passage which extends from the hollow interior of the drill bit to the cutting cone bearings.
A second conduit means i~ provided in the drill bit for receiving lubricant from an external storage source, which may be contained in a drilling subassembly. The second conduit means is in the form of a lubricant passage which intersects with and provides lubricant to the first conduit means, whereby a lubricant and gaseous fluid mixture may be formed beyond the intersection. The resulting mixture or lubricant flow is directed, through the first conduit means, to the cutting cone~ for cooling and lubrication of the cutting cone shafts and bearings. Additionally, the second conduit means may contain replaceable orifice elements which regulate the amount of lubricant _5_ 12~431~
entering the second conduit mean~ for combining with the ga3eous fluid in the fir~t conduit mean~.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a cut-away perspective view of a drill bit of the pre3ent invention:
Figure 2 i9 cro~s-sectional view taken acro~
line 2-2 in Figure l; and Figure 3 iY a cross-~ectional view of a drill bit of the present invention attached to a subassembly having an internal storage supply of lubricant.
DE.SCRIPTION OF Tl~E INVENTION
The drill bit of the present invention i3 intended to be attached to a drill string or drilling subassembly, the drill string or ~uba3sembly having a lubricant 3torage means and means for supplying the lubricant to the drill bit.
The drill bit of the present invention comprise~
a main body portion 10 as shown in Figure 1. An upper nipple 11 attaches the drill bit to a drilling subassembly, or to the extension pipe~ forming a drill string. The nipple of the drill bit i9 threaded, 80 as to threadedly engage the tapered socket of a subas~embly and form a firm connection therebetween.
One or more leg portions 12 extend downwardly from the body portion 10 of the drill bit at circumferencially spaced intervals. Mounted for rotation in each leg portion 12 is a rotary cutter 13. It is generally preferred in the industry to use a drill bit having three cutting cone~. Cutting cones 13 are rotatably mounted to the leg portion of the drill bit by bearings 14 and bearing ~haft~ 15.
Th~ dcill bit contain~ a hollow interior portion 16 forming a chamber for receiving ga~eous drilling fluid from the ~uba3~embly plenum chamber. The gaseou3 drilling fluid from chamber 16 i~ exhausted from the drill bit into the area of the cutting cone~ to pick up and remove the dust and cuttings which result from the drilling operation. l'he gaseous drilling fluid may be ejected through nozzles 17 located between the cutting cone~. Alternatively, the nozzle~ may be omitted and the gaaeou~ f1uid ejected through a central orifice located between the cutting cones, as i~ known in the art. In the present ca~e, the orifice must have sufficient restriction to provide an elevated pre3qure lS within the chamber 16.
Communicating between chamber 16 and the cutting cone bearings 14 and bearing shaft~ 15, i9 firqt conduit means 18 forming passage for the ga~eou~
drilling fluid. First conduit means 18 allows gaseous drilling fluid, ~uch as air, to pa~s from the hollow interior of the drill bit through the fir~t conduit mean~ to cool the cutting cone bearings 14 and bearing shafts 15.
The drill bit of the preqent invention is also provided with a circumferential groove 20 surrounding the drill bit, to form a reservoir for lubricant which is located in the qurface of the drill bit surrounding the nipple 11. The circumferential groove, which preferably is approximately 3/16" wide by 3/i6~ deep, receives lubricant from, for example, a supply conduit 126~311~
34 in a drilling subassembly, a~ described hereinafter in connection with Fig. 3. Second conduit means or bore 19 connect~ circumferential groove 20 with fi~st conduit means 18, and supplie~ lubricant from the groove 20 to the gaseous drilling fluid pa~sing through the fir~t conduit means 18 to the bearings. The precise point where second conduit means 19 intersects with first conduit means 18 i~ a choice of design.
In one mode of operation, the lubricant supplied by second conduit means or bore 19 i9 picked up and combined with the gaseous drilling fluid in fir~t conduit means 18, and is supplied to the cutting cone bearings 14. In this manner, a mixture of lubricant and gaseous drilling fluid is supplied to the bearing~
to achieve both a lubricating and a cooling effect.
Also, lubricant build-up and heat breakdown at the bearings i9 avoided due to the continuous supply of fresh mixture provided to the bearings, the air in the mixture acting to flush out lubricant before it ~0 accumulates.
Means is provided to regulate the amount of lubricant supplied to the bearings. To this end, second conduit means 19 may be fitted with replaceable orifices, in the present instance annular rings 21.
Z5 The diameter of the orifice in annular rings 21 may be varied to regulate the flow of lubricant supplied to the bearings. The annular rings 21 may be formed of metal, plastic, or any suitable material. The annular rings 21 are inserted into second conduit means 19 in ~0 the vicinity of circumferential groove 20, for e~ample in a counter bore 22 at the mouth of the bore 19. When 1~i431~
it i8 de~ired to modify the rate at which lubricant i~
~upplied to the bearingR, the user simply remove~ the drill bit from the ~uba~sembly, and replace~ annular ring 21 with an annular ring having a different ~ized orifice, to provide the de~ired lubricant flow.
Referring to Figure 3, the drill bit of the pre~ent invention i9 ~hown attached to a drilling ~uba~sembly. The drill bit of the pre~ent invention i~
de~igned to work in combination with a ~uba~embly having a supply of lubricant contained therein.
, ..........
-- - - A ~ubas~embly having lubricant ~torage i~ ~hown in U. S. Patent No.
3,029,881.
A repre~entative subassembly comprise~ a housing 30 and a hollow plenum chamber 31. Ga~eou~
drilling fluid from the drill line is ~upplied to plenum chamber 31, and then to drill bit interior chamber 16. The ~uba~embly ~tructure additionally contains lubricant ~torage mean~ in the form of, for example, annular chamber 32 surrounding the tlou~ing.
The flow of lubricant from the storage means may be effected in various way~. For example, a passageway 35 may be provided to allow communication between the pressurized gaseou3 fluid in the plenum chamber and the lubricant ~torage area, to act as a pressure ~ource forcing lubricant downward and into lubricant ~upply conduits 34, at spaced intervals around the circumference of the subassembly. A piston (not shown) may be provided in the annular chamber 32 to force lubricant from the chamber. It should be _g_ :IZ~318 apparent that other types of pres3ure means are equally suitable to force lubricant from the 3torage mean3, for example, an expandable liner.
The lubricant forced through supply conduit 34 accumulate~ in the circumferential groove 20 on the drill bit. In the preferred embodiment, illu~trated in Figure 2, the circumEerential groove extends entirely around the drill bit. This obviates the need to align supply conduit(s) 34 on the subassembly with individual bores or second conduit means 19 in the drill bit in order to supply lubricant to the second conduit means.
It ha~ been found beneficial to the operation of the present invention for an orifice ring 36 to be placed in the plenum chamber of the ~ubassembly in order to somewhat reduce the flow of gaseous fluid.
The orifice should be located downstream from the pressure means acting on the lubricant storage in the suba~embly, and upstream of the entrance to first conduit means 18 in the hollow interior chamber 16 of the drill bit. By varying the pressure as controlled by orific ring 36, the flow of lubricant to the bearings can be varied or controlled. In this manner, a greater pre~sure of gaseous fluid is acting upon the lubricant storage means, while a ~omewhat reduced pressure acts upon the first conduit means 18.
Sufficient force to achieve continuous lubricant flow from the chamber 32 is thereby maintained. One expedient arrangement is to place an orifice ring directly at the connection between the subassembly and the drill string below passageway 35. This allows the orifice ring to be removed or replaced ~imply by removing the suba~embly from the drill string.
i2~;~3~L~
Instead of receiving lubricant from a supply conduit in a subas~embly, the drill bit of the present invention may receive lubricant that is supplied by a conduit in the drill string from a surface-mounted supply, as sl)own in u.S. Patent No. 4,508,183. In this arrangement, the drill bit may be attached directly to the extension pipe, and the circumferential groove 20 may receive lubricant directly from the drill string conduit.
In actual operation of the aforesaid structure, it has been found that, at the operating pressures for the gaseous drilling fluid commonly employed in the drill string, the flow to the bearings through first conduit 18 is substantially entirely lubricant. The 1~ flow of lubricant to the bearings and the exclusion of any significant amount of gaseous fluid i3 believed to result from the generally higher pressure in pa~ageway 35 delivering the lubricant to conduit 18, than the flow of gaseous fluid after it has passed through orifice ring 36. As noted previou~ly, orifice ring 36 increases the back pressure above the orifice ring 36 and reduces the quantity of flow of ga3eous fluid in plenum chamber 31. ~lence, a greater pressure iq exerted upon the lubricant storage means 32 by way of ~upply conduit 35, than is present in the plenum chamber 31 and hollow bit interior 16 after the gaseous fluid has passed through orifice ring 36, which results in a lesser pressure gaseous fluid flow inside plenum chamber 31 and in hollow drill bit interior 16.
Accordingly, at the intersection between first conduit 18 and second conduit 19 in the drill bit, the gaseous fluid from the bit interior portion 16 is substantially lZ6~318 - excluded from the lower portion oE conduit 18 at the intersection of conduit 19. ~lence, the flow reaching the cutting cone bearings, through the lower portion of first conduit mean~ 18, i9 substantially entirely lubricant received at a higher pres~ure from conduit 19, with the general re~ult that no subatantial amount of gaseous fluid reache~ the bearings during normal operation. It has been found most beneficial to have the pressurized lubricant metered to the bearings in a controlled manner. ~9 noted earlier, the pressure for the lubricant flow can be controlled by varying the size of the orifice ring 36. In the preferred operation of the system, a limited quantity of lubricant i9 provided for packing the bearing~, without having an excess lubricant flow from the bearing3 into the drill hole which may permit cuttings to float back to the bearing holders and bearings.
It should also be appreciated that, in the preferred operation of the system, when the flow of lubricant of the present system is depleted, the flow of gaseous fluid acting on conduit means 18 will be such that a flow of gaseous fluid is provided to the bearings. Accordingly, in the event the supply of lubricant in ~torage means 32 is exhausted or interrupted, the bearings are nonetheless given some degree of protection by the cooling effect of gaseous fluid supplied to the bearings by first conduit means 18 until such time as the lubricant supply is replenished or reestablished.
In a preferred embodiment of the present invention, a perforated member 40 in the form of a slotted tube is fitted into the mouth of the first lZ6~3~
conduit 18 and act~ to filter dirt, ~tone, or other heavy material which may be pre3ent in the gaqeous drilling fluid from entering the fir~t conduit means 18.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In combination with a drilling system having a drill string, a source of gaseous fluid at a controlled pressure providing a flow in the drill string and lubricant supply means providing a forced flow of lubricant under the pressure of said source of gaseous fluid, said drill string including a flow restricting orifice which controls the flow of gaseous fluid in the drill string and regulates the gaseous fluid pressure exerted on said lubricant supply means, a drill bit comprising:
(a) a body portion having a hollow interior;
(b) a shank portion extending from said body portion for attachment of the drill bit to the drill string and having an opening for receiving the gaseous fluid flow from the drill string for conducting the flow into the hollow interior of the body portion, the body portion having at least one leg portion extending from said body portion;
(c) at least one cutting cone supported on said leg portion by bearings (d) the body portion having at least one discharge opening communicating with said hollow interior for exhausting gaseous fluid from the hollow interior onto the surface being drilled;
(e) at least one first conduit means extending through the leg portion providing gaseous passage means communicating between said hollow interior of the body portion and said cutting cone bearings, the first conduit means receiving a gaseous fluid flow from the interior of the body portion: and (f) second conduit means communicating with said first conduit means at a junction and extending through the body portion providing passage means for the lubricant, and communicating at one end with said forced flow of lubricant from said lubricant supply means and at the other end with said first conduit means at said junction.
(a) a body portion having a hollow interior;
(b) a shank portion extending from said body portion for attachment of the drill bit to the drill string and having an opening for receiving the gaseous fluid flow from the drill string for conducting the flow into the hollow interior of the body portion, the body portion having at least one leg portion extending from said body portion;
(c) at least one cutting cone supported on said leg portion by bearings (d) the body portion having at least one discharge opening communicating with said hollow interior for exhausting gaseous fluid from the hollow interior onto the surface being drilled;
(e) at least one first conduit means extending through the leg portion providing gaseous passage means communicating between said hollow interior of the body portion and said cutting cone bearings, the first conduit means receiving a gaseous fluid flow from the interior of the body portion: and (f) second conduit means communicating with said first conduit means at a junction and extending through the body portion providing passage means for the lubricant, and communicating at one end with said forced flow of lubricant from said lubricant supply means and at the other end with said first conduit means at said junction.
2. The combination set forth in claim 1 wherein the lubricant supply means is connected to the source of gaseous fluid upstream of the orifice to control the pressure of the lubricant supply means.
3. The drill bit set forth in claim 1 wherein said lubricant supply means consists of a circumferentially groove surrounding said body portion.
4. The drill bit set forth in claim 3 wherein said circumferential groove is provided with orifice rings at the point of communication with said second conduit means to control the amount of lubricant supplied to said second conduit means.
5. The drill bit set forth in claim 3 wherein the first conduit means contain a perforated member at the point of communication with the hollow interior.
6. An earth boring drill bit for use in a drilling system having a source of gaseous fluid at a controlled pressure providing a flow in a drill string of the system and having a lubricant supply means containing lubricant under the pressure of said source of gaseous fluid for providing a forced flow of lubricant in the drill string, the drill bit comprising:
(a) a body portion having a hollow interior;
(b) a shank portion extending from said body portion for attachment of the drill bit to the drill string and having an opening for receiving the gaseous fluid flow from the drill string for conducting the flow into the hollow interior of the body portion, the body portion having at least one leg portion extending from said body portion;
(c) at least one cutting cone supported on said leg portion by bearings;
(d) the body portion having at least one discharge opening communicating with said hollow interior for exhausting gaseous fluid from the hollow interior onto the surface being drilled;
(e) at least one first conduit means extending through the leg portion providing gaseous passage means communicating between said hollow interior of the body portion and said cutting cone bearings, the first conduit means receiving a gaseous fluid flow from the interior of the body portion; and (f) second conduit means communicating with said first conduit means at a junction and extending through the body portion providing passage means for the lubricant and communicating at one end with said forced flow of lubricant from said lubricant supply means and at the other end with said first conduit means at said junction; and (g) a flow-restricting orifice ring controlling the flow of gaseous fluid in the drill string and wherein the lubricant supply means is connected to the source of gaseous fluid upstream of the orifice ring to control the pressure exerted on the lubricant supply means.
(a) a body portion having a hollow interior;
(b) a shank portion extending from said body portion for attachment of the drill bit to the drill string and having an opening for receiving the gaseous fluid flow from the drill string for conducting the flow into the hollow interior of the body portion, the body portion having at least one leg portion extending from said body portion;
(c) at least one cutting cone supported on said leg portion by bearings;
(d) the body portion having at least one discharge opening communicating with said hollow interior for exhausting gaseous fluid from the hollow interior onto the surface being drilled;
(e) at least one first conduit means extending through the leg portion providing gaseous passage means communicating between said hollow interior of the body portion and said cutting cone bearings, the first conduit means receiving a gaseous fluid flow from the interior of the body portion; and (f) second conduit means communicating with said first conduit means at a junction and extending through the body portion providing passage means for the lubricant and communicating at one end with said forced flow of lubricant from said lubricant supply means and at the other end with said first conduit means at said junction; and (g) a flow-restricting orifice ring controlling the flow of gaseous fluid in the drill string and wherein the lubricant supply means is connected to the source of gaseous fluid upstream of the orifice ring to control the pressure exerted on the lubricant supply means.
7. In combination with a gaseous fluid drilling subassembly having a storage means for lubricant stored under the pressure of the gaseous drilling fluid, and having replaceable orifice means for regulating the pressure exerted by the gaseious fluid upon the stored lubricant, an earth boring drill bit comprising:
(a) a body portion having a hollow interior;
(b) a shank portion extending from said body portion for attachment of the drill bit to the drill string and having an opening for receiving gaseous fluid from the subassembly for conducting the flow into the hollow interior of the body portion, the body portion having at least one leg portion extending from said body portion;
(c) at least one cutting cone supported on said leg portion by bearings;
(d) the body portion having at least one discharge opening communicating with said hollow interior for exhausting gaseous fluid from the hollow interior onto the surface being drilled;
(e) at least one first conduit means extending through the leg portion providing gaseous passage means communicating between said hollow interior of the body portion and said cutting cone bearings, the first conduit means receiving the gaseous fluid flow from the interior of the body portion; and (f) second conduit means communicating with said first conduit means at a function and extending through the body portion providing passage means for lubricant, and communicating at one end with the storage means in the subassembly and at the other end with the first conduit means at said junction;
whereby when said storage means contains lubricant therein, a flow of lubricant within said second conduit means is provided at a controlled flow rate through said first conduit to the bearings with or without a flow of gaseous fluid.
(a) a body portion having a hollow interior;
(b) a shank portion extending from said body portion for attachment of the drill bit to the drill string and having an opening for receiving gaseous fluid from the subassembly for conducting the flow into the hollow interior of the body portion, the body portion having at least one leg portion extending from said body portion;
(c) at least one cutting cone supported on said leg portion by bearings;
(d) the body portion having at least one discharge opening communicating with said hollow interior for exhausting gaseous fluid from the hollow interior onto the surface being drilled;
(e) at least one first conduit means extending through the leg portion providing gaseous passage means communicating between said hollow interior of the body portion and said cutting cone bearings, the first conduit means receiving the gaseous fluid flow from the interior of the body portion; and (f) second conduit means communicating with said first conduit means at a function and extending through the body portion providing passage means for lubricant, and communicating at one end with the storage means in the subassembly and at the other end with the first conduit means at said junction;
whereby when said storage means contains lubricant therein, a flow of lubricant within said second conduit means is provided at a controlled flow rate through said first conduit to the bearings with or without a flow of gaseous fluid.
8. The combination set forth in claim 7 further comprising replaceable annular rings within said second conduit means for further regulating the flow of lubricant to the first conduit means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US81832686A | 1986-01-13 | 1986-01-13 | |
| US818,326 | 1992-01-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1264318A true CA1264318A (en) | 1990-01-09 |
Family
ID=25225263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000525593A Expired - Fee Related CA1264318A (en) | 1986-01-13 | 1986-12-17 | Drill bit |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0230129A1 (en) |
| AU (1) | AU6743787A (en) |
| BR (1) | BR8700047A (en) |
| CA (1) | CA1264318A (en) |
| MX (1) | MX160907A (en) |
| ZA (1) | ZA87174B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5183123A (en) * | 1991-11-13 | 1993-02-02 | Western Rock Bit Company Limited | Indicating means for a rock bit lubricating system |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3125175A (en) * | 1964-03-17 | figure | ||
| US2814464A (en) * | 1953-01-02 | 1957-11-26 | Engineering Lab Inc | Air course drill bits |
| US3029881A (en) * | 1959-06-09 | 1962-04-17 | H C Smith Oil Tool Co | Bit lubricator |
| US3924695A (en) * | 1974-10-02 | 1975-12-09 | John R Kennedy | Rotary drilling method and apparatus |
| US4080091A (en) * | 1976-11-03 | 1978-03-21 | Reed Tool Company | Drill bit |
| US4375242A (en) * | 1980-08-11 | 1983-03-01 | Hughes Tool Company | Sealed and lubricated rock bit with air protected seal ring |
| US4386668A (en) * | 1980-09-19 | 1983-06-07 | Hughes Tool Company | Sealed lubricated and air cooled rock bit bearing |
| EP0106701A3 (en) * | 1982-10-19 | 1986-02-05 | Drumco | Method and apparatus for lubricating a drill bit |
| US4541494A (en) * | 1982-10-19 | 1985-09-17 | Drumco | Drill bit assembly |
-
1986
- 1986-12-16 EP EP86309813A patent/EP0230129A1/en not_active Withdrawn
- 1986-12-17 CA CA000525593A patent/CA1264318A/en not_active Expired - Fee Related
-
1987
- 1987-01-08 AU AU67437/87A patent/AU6743787A/en not_active Abandoned
- 1987-01-08 BR BR8700047A patent/BR8700047A/en unknown
- 1987-01-12 ZA ZA87174A patent/ZA87174B/en unknown
- 1987-01-13 MX MX4927A patent/MX160907A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5183123A (en) * | 1991-11-13 | 1993-02-02 | Western Rock Bit Company Limited | Indicating means for a rock bit lubricating system |
Also Published As
| Publication number | Publication date |
|---|---|
| AU6743787A (en) | 1987-07-16 |
| EP0230129A1 (en) | 1987-07-29 |
| BR8700047A (en) | 1987-12-01 |
| ZA87174B (en) | 1987-08-26 |
| MX160907A (en) | 1990-06-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |