CA1182105A - Method of manufacturing large diameter oil well drilling bit and large diameter oil well drilling bit - Google Patents
Method of manufacturing large diameter oil well drilling bit and large diameter oil well drilling bitInfo
- Publication number
- CA1182105A CA1182105A CA000394154A CA394154A CA1182105A CA 1182105 A CA1182105 A CA 1182105A CA 000394154 A CA000394154 A CA 000394154A CA 394154 A CA394154 A CA 394154A CA 1182105 A CA1182105 A CA 1182105A
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- Canada
- Prior art keywords
- lug
- cutter
- oil well
- bit
- drilling bit
- Prior art date
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Abstract
ABSTRACT OF THE INVENTION
The present invention discloses a large diameter oil well drilling bit which utilizes a unique cast body upon which are secured a plurality of cutting assemblies comprising a leg, a bearing journal and a rolling cutter mounted on the bearing journal.
The present invention discloses a large diameter oil well drilling bit which utilizes a unique cast body upon which are secured a plurality of cutting assemblies comprising a leg, a bearing journal and a rolling cutter mounted on the bearing journal.
Description
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METHOD OF MANUFACTURING
LARGE DIAMETER OIL WELL DRILLING BIT
& LARGE DIAMF.TER OIL W:ELL_DRILLING BIT
BACXGROUND OF THE INVENTION
The present invention generally involves oil well drilling bits, and more particularly discloses the large diameter drilling bits commonly termed, "top hole" bits used to drill the very first section of borehole beginning at the ground surface, and are also used for drilling casing openings. The -top hole bi-ts 10 generally range in size from about 18 inches up to about 28 inches and are very cumbersome and heavy. Generally, top hole bits comprise either four-cutter bits commonly called, "cross cutter"
bits, or else they comprise tri-cone rolling cutter bits such as that disclosed herein. The general method of manufacturing large 15 tri-cone rolling cutter bits is in the segmen-ted arc construction method. This method utilizes three 120-clegree arcuate lug sec-tions, each comprising one-third of the drill bit body and an in-dividual leg portion with a bearing journal thereon. These three arcuate sections are usually forged and then machined to form the 20 bearing surfaces on the bearing journals and the mating surfaces ~`
along each edge where the three sections are welded together.
Prior to joining the three arcuate sections to form a cylindrical body, the cutter assembly with bearlngs and retention means must first be mounted on the inwardly projecting bearing journals be-cause of the impossibility of so mounting the cutters after thethree arcuate sections have been welded together.
After the bearing assemblies and cutters are mounted on the machined bearing journals, the three lugs are then placed in a welding jig and welded to each other to form the cylindrical bit body. After this welding has occurred a tapered thread is machined on the upper end of the bit, which tapered threaded end is commonly referred to as the "pin" end, and the bit is ready for use. The difficulties with this assembly method in manufac-turing tophole or large diameter bits is that because of the size of these bits, minor variations and tolerances in alignments of the three lug sections results in substantial final errors in the bit specifications and dimensions. The forged lug sections of the prior art bits are relatively rouyh and inaccurate and the machining of the mating surfaces likewise is c~lfficult to control to close tolerances. When the three lug sections are eventually welded together to form a single cylindrical structure wit.h cut-ter assemblies already permanently motmtecl thereon, most often the results are that the cutters are not only non-concentric about the rotational axis of the bit, but the cutters also extend dif-ferent distances downward from the pin end of the bit. Thus,one cutter may extend further downward than the other two and may provide almost all of the cutting action on the borehole bottom until that cutter is worn substantially to match the shorter two cutters. This tends to cause premature failure of either the 3~ bearings or the cutter shell on that one cutting assembly, which in turn will result in early failure of the bit. Likewise, ra-dial placement of the lucJs is diffic~lt to control and ma~ resultin the drill bit cutting under gage, which is undesirable because of the borehole being smaller than necessary and smaller than specified. Also, if one cutter extends radiall~ further outwar~
than either one or both o~ tl~e other cutters, a resulting effect could be " tracking" of the cutting teeth on the cutters and even-tual gyratiOIl or orbiting action of the bit about the rotational a~is thereby s~stantially eliminating the cutting efficienc~ of the bit.
l'he present invention elimina-tes these disadvantages found in the big diameter or top hole bits by providing a struc-ture that is much more easily assembled and in whicn tolerances can be closely controlled during assembly of the bit. Further disclosure is made of a method of assembli:ng the bit to provide extremely close tolerances in the radial and axial directions of the cutter assemblies. Also disclosed is 2 method of varying the offset of the cutter axes by relatively simple and inexpensive means during construction of the bit. The invention is achieved by utilizing a cast bit body which is formed in a single section and which has three platform areas formed tnereon for receiving three independent cutter assemblies which are then welded to the cast iron body. Each cutter assembly has a countersunk alignment point which is engaged by the hydraulic or mechanical alignment tool which forms a part of this invention. The alignment tool fixes the cutter assemblies in place on the cast metal body where-upon they are welded in place to form a highly accurate, closetolerance, large diameter tri-cone drilling bit.
Thus, according to the present invention, there is provided an oil well drilling bit for drilling large diameter boreholes which comprises an integrally formed cast metal body member having a pin end, a central bore passage, and a plurality of equispaced platform arms formed thereon. The platform arms -3 ~
s each have two different planes of machined alignment surfaces thereon in abutting relationship. A lug assembly is welded to each of the platform arms and has a lug member at one end and an inwardly projecting bearing ~ournal at its opposite end and further has a frustoconical cutter rotatably mounted on the bearing journal by bearing means. The body member and the lug members form one of at least two drill bits of significantly different diameters.
In a further embodiment, the invention contemplates an oil well tricone rolling cutter drilling bit for drilling top hole and large diameter boreholes and comprises an integrally formed cast metal body member having a pin end, a central bore passage, and three equispaced platform arms formed thereon. The platform arms each have a plurality of alignment surface means comprising two different planes for a lug assembly in abutting relationship while permitting verti-cal, horizonta:L, and skew adjustment during assembly and adapted to support a lug assemhly of a size selected from at least two different sizes. A lug assembly of a size selected from at least two different sizes are welded to each of the platform arms and has a lug member with a ley section at its attachment end and a bearing journal extending radially inwardly at its opposite end. The journal is adapted to support a cutter of a size selected from at least two different sizes, and the lug assembly further has a frustoconical cutter of a size selected from at leas-t two different sizes rotatably mounted on the bearing journal by bearing means. The b~dy member and the lug member form one of at least two differently sized drilling bits of significantly different diameters.
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The invention also encompasses the novel method of manufacturing a plurality of sizes of oil well drilling bits and comprises forming an integral body member having a tapered end and a plurality of outwardly extending platform arms thereon, with each of the arms having a plurality of surfaces adapted to receive and support a cutter-supporting lug member in abutting relation thereto and permitting adjustable movement of such lug member in a vertical or horizontal direction during assembly.
Lug members are formed in a plurality of sizes operable to fit each of the platform arms, with each lug member having an attach-ment end and, at the opposite end, an inwardly projecting bearing journal. Rotatable cutter members are formed in a plurality of sizes and are constructed so that each size lug member fits two different sizes of the cutter members. A lug member of predeter-mined size is se:Lected for installation on each of the platformarms, and a cutter member is selected from the different sizes which fit the selected lug member. The selected cutter members are rotatably mounted on respective ones of the lug members with bearing means therebetween, prior to securing the lug members on the body member. Each of the selected lug members, with cutter members mounted thereon, is placed in operative engagement with at least two of the surfaces on respective ones of the platform arms. Each selected lug member is adjusted to a preselected position while maintaining operative contact with the platform arm surfaces. The lug members are clamped in the preselected position, and are welded to the platform arms while being main-tained in the preselected position.
BRIEF DESCRIPTION OF THE DRAWINGS
. . . _ Figure 1 is a side elevational view of the present invention showing the bit body and a typical cutter assembly in -3b-: ,-cross-sectional view Figure 2 is an axlal view of the cast metal body of the bit prior to the cutter assemblies being joined thereto. Figure 3 is a partial schematic drawiny taken in a radially outward direction of one cutter assembly illustrating its mounting on the cast bi-t body. Figure 4 is a block diagram illustrating the interchangeability of parts throughout the bit and the assembly method for obtaining four different bit sizes.
Figure 5 is a schematic axial view of the bit body illustrating the sweeping pattern of the nozzle system located thereon. Figure 6 is a schematic side view of the bit showing one cutter arm in place. Figure 7 is a close-up, broken-out view showing the align-ment method for assembling the bi-t. Figure 8 is a schematic view of the alignment system for assembling the cutter assemblies on the bit body.
DESCRIPTION OF ~HE PREFERRED EM3ODIMENTS
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Referring now to the figures, and more particularly to Figure l, a tri-cone, rolling cutter drill bit according to the present invention is partially disclosed in cross-sectional view in Figure 1. Figure 1 illustrates the body and a typical lug assembly attached to the body. In normal procedure a tri-cone bit, according to this invention, would comprise a body and three of the leg assemblies as shown attached to the body in relatively equidistant relationship around the body; i.e., at approximately 120-degree intervals. In Figure 1, the tri-cone drill bit 10 comprises a single, integrally formed, steel body 11 having a central bore area 12 and a tapered pin section 13. Cen-tral bore 12 communicates through pin area 13 via pin bore 14. Three outwardly extending platforms 15 (only one shown) are integrally formed on body member 11 during the fabrication of the body member. Plat-form 15 generally comprises a relatively flat, upward-facing, moun-ting surface ~6 and a relatively flat, vertical, shoulder ~but-ment 17 joined with surface 16 to form an L-shaped mountiny plat-form for the lug assembly 18.
In one partlcular embodiment of the present invention, the body member 11 was formed in a single operation by means of casting from suitable steel alloy. By utilizing selective cast-ing techniques and e~tremely accurate casting, body member 11 can be obtained having a close-tolerance tapered section 13 and being close to tolerance on surfaces 16 and 17 of arm 15. In this par-ticular embodiment, tapered pin 13 was accurate enough to providealignment of the body member for final machining of surfaces 16 and 17 prior to attachment of lug assembly 18 thereto. The ma-chining of surfaces 16 and 17, because of the accuracy of the cas~
ting techniques, generally nèeds only a minor bit of machine work to smooth up the area for abutment of leg assembly 18~ Alterna-, tive to machining surfaces 16 and 17 off of the alignment with unflnished tapered pin 13 is to machine the final threaded por-tion on the external surface of pin 13, (which threaded surface is utilized to interconnect the drill bit with the drill string), and then threading the tapered end 13 into a female threaded alignment jig before machining surfaces 16 and 17.
The lug assembly 18 comprises, a unitary lug member 19 which in this embodiment was formed in a forging operation.
Lug 19 comprises leg section 20 having a L-shaped end with hori 25 zontal surface 21 and vertical surface 22. Surfaces 21 and 22 preferably are machined on leg section 20 to match surfaces 16 and 17 and provide proper alignment of leg assembly 18 on member 11~ At the upper end of lug member 19 (as shown in Figure 1), a compound bearing journal 23 is formed on the lug member during the forging operation and ls final-machined to provide roller bear-o~;
ing surfaces 24 and 25. ~lso a ball bearing race 26 is formed on journal 23 as well. as a thrust bearing recess 27. Alternative-ly, roller bearlng races 24 and 25 could be replaced with fric-tion bear;.ng surfaces should the bit manufacturer wish to utilize 5 sleeve-type frlction bearings in place of the roller bearings as disclosed herein.
A plurality oE roller bearings 28 are located in roller bearing recess 24 to substantially encircle bearing jour-nal 2 3 and provide rotatable contact with the cutter mounted there-10 on. Likewise, a set of smaller roller bearings 29 are locatedi.n roller bearing recess 25. A plurality of ball bearings 30 are located in ball bearing race 26 to encircle bearing journal 23.
A small, flat, circular thrust disc 31 is located in thrust re-cess area 27. Thrust disc 31 may be comprised of any suitable 15 bearing material such as copper, steel or any of the softer metals such as lead, s ilver, indium; or may be formed of any combinatlon of these elements. Roller bearings 28 and 29 and ball bearings 30 are preferably formed of a hard, tough metal alloy such as steel, which i.s suitable for receiving high loads without galling or 20 spalling. Such alloys are well known in the art and not disclosed herein.
, Each of the three lug members 19 are preferably lo-cated on platorms 15 of body member 11 and attached thereto by welding as shown in Figure 1 at 32. Welding is performed 25 along a weld groove 33, which is formed along the outer edge of leg section 20 around surfaces 21 and 22. The particular weld configuration may be seen more clearly in Figure 3 where like numbers represent identical elements.
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s Each lug member 19 also has rotatably mounted thereon a generally frusto-conical cutter 34 having a plurality of cut-ting elements or teeth 35 protruding outwardly therefrom. In this particular embodiment the cutter 34 ls formed by casting of a high-strength, tough, steel alloy and the teeth 35 are integrally formed thereon. These teeth are generally wide and flat and represent a general chisel shape. Alternatively, the cutters may be formed by forging a frusto-conical cutter blank of suffi-cient size to include the integral teeth. After the forging opera-tion material is machined away to leave the protruding chisel-shaped teeth.
The embodiment shown in Figure 1, as mentioned previ-ously, is a tri-cone bit, although only a single lug assembly is shown for simplification reasons. The illustration in Figure 1 does show the tooth profile of all three cutters of the bit super-imposed upon the single cutter 34. The illustration of cutter 34 is that of the number two cutter on the bit. The teeth of the number one cutter are shown at 36, and the teeth of the numb~r three cutter are shown at 37. Thusl while it was not neces-sary to show all three of the lug assemblies 18 in order to fullydisclose the tri cone bit since each of the cutters 34 have a dif-ferent tooth arrangement to allow for better bottomhole coverage and better intermesh of the teeth without interference betweer.
adjacent teeth, the profiles of the three cutters are combined to illustrate the total bottomhole tooth coverage. Figure 7 bet-ter illustrates the individual cutter profiles showing the indi-vidual spacing relationships of the teeth for each cutter.
One particular feature of the present invention is illustrated in Figure 1 by the lines drawn in phantom thereon.
In the lug member 19, an alternate surface 38 is shown drawn in )s phantom. Likewise, in cutter 34, an alternate ~aye surface 39 is shown in pllantom. These alternate surfaces will be explained in more detail with reference to the description relating to Figure 4~ ~
S In addition to the attacllment of lug assembly 18 to body member 11 on platform 15, the body member has additional elements as disclosed in Figure 1. A plurality of fluid jetting nozzles are located in sufficiently sized openings formed through the central upper porti.on 40 of body member 11 communicating with central bore 12. ~he nozzles comprise a single center nozzle 41, a plurality of intermediate nozzles 42, and a plurality of outer nozzles 43. The angular orientation o~ the intermediate nozzles 42 is shown in relation to a vertical axis Vl drawn ~rough the center of the nozzle 42. One nozzle in this embodiment was placed at an angle of five degrees, the second intermediate nozzle was angled at fifteen degrees, and the thlrd intermediate nozzle was angled at twenty-five degrees from axis Vl. Likewise, the angu-lar displacement of the outer nozzles,43 can be shown with res-pect to a vertical axis V2 drawn through the center of outer noz-zle 43. In this particular ernbodiment, nozzles 43 are angled at 25 degrees from axi.s V2.
P~eferring now to Figure 2, a top view looking down the central rotational axis is ill,ustra-ted showing the body mem-ber 11 prior to assembly of the lug assemblies 18. In Figure 2 the cen-ter nozzle 41, the intermediate nozzles 42 and the outer nozzles 43 are shown in relationship to each other. The outer nozzles 43 are located in recessed areas or valleys 44 formed in body member 11. The angular placement of the intermediate nozzles 42 is i.ndicated by the phantom lines extending downward 3~ therefrom which illustrate the location of the nozzle bodies .
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inside their openin~s which h~ve been cast or machined into body member 11. Nozzles 41, 42 and 43 may be retained in me~ber 11 by any of se~eral alternate methods such as threading, press-fitting, welding and retention by snap rings.
Figure 5 is a schematic diagram showing a top axial view of body member 11 after the h~draulic nozzle system has been installed but prior to attachment of the lug assemblies 18. The schematic diagram of Figure 5 illustrates the spiral or sweep pattern of the nozzles as installed. The seven nozzles thus arranged allow the cleaning of different sections of the bit and the borehole, starting with the center nozzle and moving radially outward towards the outer nozzles, which are directed to the gage area being cut in the borehole.
Referring now to Figure 3, a radial view of one lug member 19 is disclosed welded in place on body member 11. The cutter 34 has been omitted in order to better illustrate the method of welding the member l9 to member 11. In this embodiment a weld channel has been formed by beveling the outer edges of the lower end 20 of lug member 19 so that weldment may be formed between leg section 20 and pla-tform 16 and 17. The weldment i5 illustrated in Figure 3 at 32.
Referring now to Figure 7, the three typical cutters utilized on the bit of this embodiment have been cross-sectioned and laid out in a profile to illustrate intermesh of the teeth amongst the set of three cutters for one bit. Likewise, Figure 7 illustrates the placement of the fluidic nozzles with respect to the cutters to show the flow of drilling fluid therebetween.
It should be noted that because of the three-dimensional aspect of the cutter placement, the three-dimensional cutter profile in-dicated in Figure 7 must involve splitting one of the cutters in half to more realistically de~ine the -three-dimensional relation ship in a two-dimensional, planar drawiIIg. From Figure 7 it can be seen that the nozzle system is primarily directed to the in-ter-mesh areas between the cutters to better sweep cut-tings Erom the borehole face as they are broken out. It is preferred that no nozzle be directed against a cutter shell because of the inherent problems arising from fluid erosion when the nozzles are directed against the cutter bodies.
Figures 6 and 8 illustrate in schematic diagram the system for assembling the lug assemblies on the body member. The system primarily consists of a relatively large, flat base plate 45, having three interspaced sliding aligriment arms 46 located thereon, which alignment arms are arranged to be brought into contact with the radially outward portion of leg section 20.
The alignment arms 46 are spaced at intervals of 120 degrees around plate 45 from each other when ~he embodiment of the inven-tion is that of a trl-cone bit. Base plate 45 has a tapered open-20 ing 47 for receiving tapered pin section 13 of body member 11.
Pin opening 47 may be either internally threaded to match the ex-, ternal threaded portion of pin 13 or may be smooth-walled to re-ceive either the threaded pin end 13 or could be used to receive pin end 13 prior to the threads having been machined thereon.
In either instance, opening 47 preferably is dimensioned to snugly fit pin end 13 and secure body member 11 in a rigid, stationary position to accurately locate lug assemblies 18 thereon. The align-ment arms ~6 are relatively rigid and preferably allowed movement only in a radially outward and inward direction. Movement of arms 46 can be controlled by means well known in the art such as elec-trical, hydraulic, mechanical or pneumatic.
Figure 6 is a schematic illustration of a portion of Figure 8 broken out and enlarged to better illustrate the align-ment technique for aligning lug member 19 on platform 15. The end of each alignment arm ~6 is formed with a particular geomet-ric configuration such as a right circular cone 47 e~tending ra-dially inward towards the lug member 19. Likewise, a complemen-tary indentation ~8 is formed in lug member 19 to receive the geo-metric end 47 of arm 46. When such configuration as a conical end 47 and a conical indentation 48 are used, it can be seen that movement radially inward by arm 46 when it contacts the indenta-tion 48 will locate member 19 in an identical position each andevery time. Should a misalignment occur, the force of arm 46 mov-ing inward into opening 48 will move member l9 until the geomet-ric end 47 is completely embedded in socket 48, thereby providing proper alignment. ~t that time should there be spacing between lug member l9 and platform 15, a requisite number of metal shim plates 49 may be inserted prior to ~elding of lug member l9 on platform 150 It should be noted that although Figure 8 illustrates a single lug member being attached to the body member, all three such members may be attached simultaneously for optimum alignment of the lug assemblies. It should also be pointed Ollt that the three lug assemblies 18 are completely assembled, including all bearings, seals and cutters, prior to attachment to body member ll because of the impossibility of attaching the cutters after the lugs l9 have been welded to the bodyO The lug assemblies 18 have been simpli~ied in Figure 8 to more cl~arly illustrate the method o assembly, but in the preferred embodiment, the three lug assemblies 18 in complete assembly form are attached to body member 11 simultaneously by the use of welding techniques in con~
junction with alignment system 45.
Figure 4 illustrates a schematic block diagram show-ing the versatility of the present invention in forming different . . .
sizes of bits using interchangeability of various components~
~or instance in ~his particular embodiment, a single body casting ll can be utilized in forming four different diameter bits. This body casting can be used in a 20-inch bit, 22-inch bit, 24~inch bit and 26-inch bit. In order to manufacture these four sizes of bits, two different lug members 19 are utilized -- l9a and l9b.
Lug member l9a is utilized to form a 20-inch bit and a 22-inch bit. These two bits utilize -the same body casting and the same lug, but use different size cutters 34a and 34aa. Likewise, the two larger bits r the 24-inch diameter and the 26-inch diameter, each use the same body casting ll and the same lug l9b, but like-wise use two different cutters 34b and 34bb. Thus, the manufac-ture of four different size bits ranging from 20-inch diameter to 26-inch diameter requires only a single type body member, two different types of lugs and four different size cutters.
In addition to this tremendous fle~ibility and effi-ciency in assembly, further optimum savings can be obtained by utilizing~lug members 19a and l9b, which are substantially iden-tical except in on]y a small particular area. For instance, re-ferring back to Figure 1, the lug member l9a of Figure 4 can beseen in Figure l is defined by the phantom line 38. The larger lug member 19~ is defined by the outer line of member 19 rather than the phantom line 38. Similarly, optimum efficiency in manu-facture of cutters 34 can be achieved by casting the individual cutters and utilizing casting shells that are identical in many respects.` The smaller cutters 34a and 34aa are defined by the phantom lines 39 whereas the larger cutters 34b and 34bb are de-fined by the outer lines along the gage surface rather than thephantom lines 39. Thus, by merely changing the gage portion of the cutters at 39 and by changing the radial outward shoulder areas at 38 of the lugs and also by the use of a single body member 11, S
four different 5ize bits can ~e manufactured basically using sub-stantially the same amount of tooling and casting equipment as would normally be required in a single diameter bit.
With the great advancements in casting techniques re-cognized today, such as the investment casting and centrifugal casting methods, the cutters 34 having the integrally formed teeth provide a cutter of identical quality to the conventional method of machining the cutters. Because of the accuracy of modern cast-in~ techniques, the cutter dimensions and the teeth configurati~ns are acceptable in the casting and need no machining except in the minor bearing areas internally in the cutter. Preferably, the lug members 19 are forged and machined in the bearing areas be cause of the strength requirements and the simplicity in forging this relatively uncomplicated shape. The body members 11 prefer-ably are cast in a single operation to form a single, integral body section which ls relatively inexpensive to cast and in which the final casting has substantially all of the external dimensions within acceptable tolerances. l'he only remaining machining is the shoulder areas lS and in some cases the nozzle bores for the 20 fluidic nozzles 41, 42 and 43. In addition the threaded pin end 13 is machined after the casting. The casting of body member 11 utilizing the known casting techniques is accurAte enough that the alignment system 45 can be utilized with the cast pin end 13 even prior to machining of the pin threads thereon.
SU~ARY OF TEIE INVENTION
The present invention is directed to a multi-cutter, rolling cone drill bit for use in large diameter boreholes, particu-larly the initial borehole at the top of the drilling operation.
mhese bits are generally of the three-cone configuration and are termed, "top hole" bits. The present invention discloses a top hole bit of extremely accurate external dimensions and a method of manufactu~ing this bit utili~ing fle~ibility in part selection and interchangeability of parts to provide various sizes of bits from con~on components. The present invention utilizes an in-te-gral cast body rather than the three arcuate segments of the prior art bits. The invention utilizes two sets of forged lugs to pro-vide four sizes of bits.
Likewise, this invention utilizes cast metal cutters10 rather than machined cutters with four different cutters for the four bit sizes. The two smaller size cutters differ only in the small gage area along the large part of the cone. Also, the two larger diameter bits utilize two different cutter configurations which differ from each other only in the small area added along the gage of the cutter. In addition to these features, the pre-sent invention discloses a spiral sweep nozzle arrangement uti-lizing seven nozzles in a fluidic system which is particularly advantageous in cleaning the entire bottom of the borehole as itis being drilled.
Furthermore, an additional feature and advantage of this invention i5 the ease and accuracy of the as~embly method.
The body member is securely attached in a base plate or table to which are slidably attached three alignment armC having geomet-rical alignment ends for matching engagement in the lug assemblies.
It should be noted here that in addition to providing close align-ment of the lug assemblies, an easy method of introducing skewed axes into these bits reveals itself with the present alignment system. For instance, if a particular skew dimension in the jour-nal axis is desired, the correlative amount of offset in the align-ment indentation 48 can be introduced into each of the lugs such .. .. . . . . ....
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that the alignment arm ~6 properly positions each luy to obtain the desired a~is skew. Thus, the bi-t axis s]~ew can-be controlled very closely by simply relocating the aliynment indentations 48 in each of the lugs. Likewise, proper axial alignment, i.e., height of the cutters above the body men~er, is easily obtained by the alignment system 46 in conjunction wi-th -thin metal shims ~g.
In addition to this extremely close control over the height measurements of the three cutter cones, which height con-trol allows a proper weight and wear distribution on each of the three cones, the radial measurements of the three cutters can be held to close tolerances by the same shi~ning methods along sur-face 17. Thus, the cutters, b~ proper shimming on surfaces 16 and 17, will end up properly balanced with respect to load and each sharing proportionately in the cutting of the gage diameter.
This greatly reduces rapid wear and failure of the cutter assem-blies and provides proper gage cutting action. Thus, it can be seen that the present invention involves large bits and their meth-od of manufacture, which bits offer advanced techniques for ease of assembly and for close control of critical tolerances.
Although certain preferre~ embodiments of the inven-tion have been herein descrihed in order to provide an understand-ing of the general principles of the invention, it will be appre-ciated that various changes and innovations can be effected in the described large diameter, tri-cone drilling bit without de-parting from these principles. For example, it is obvious that one could alter the number of lug assemblies provided in the bit to include more than the three assemblies illustrated. Also, rath-er than utilizing cut-ters which are formed by casting, one could utilize machined cutters instead. The invention, therefore, is declared to cover all chan~es and modifications of a specific ex-ample herein disclosed for purposes of illustration which do not constitute departures from the spirit and scope of the inventi.on.
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METHOD OF MANUFACTURING
LARGE DIAMETER OIL WELL DRILLING BIT
& LARGE DIAMF.TER OIL W:ELL_DRILLING BIT
BACXGROUND OF THE INVENTION
The present invention generally involves oil well drilling bits, and more particularly discloses the large diameter drilling bits commonly termed, "top hole" bits used to drill the very first section of borehole beginning at the ground surface, and are also used for drilling casing openings. The -top hole bi-ts 10 generally range in size from about 18 inches up to about 28 inches and are very cumbersome and heavy. Generally, top hole bits comprise either four-cutter bits commonly called, "cross cutter"
bits, or else they comprise tri-cone rolling cutter bits such as that disclosed herein. The general method of manufacturing large 15 tri-cone rolling cutter bits is in the segmen-ted arc construction method. This method utilizes three 120-clegree arcuate lug sec-tions, each comprising one-third of the drill bit body and an in-dividual leg portion with a bearing journal thereon. These three arcuate sections are usually forged and then machined to form the 20 bearing surfaces on the bearing journals and the mating surfaces ~`
along each edge where the three sections are welded together.
Prior to joining the three arcuate sections to form a cylindrical body, the cutter assembly with bearlngs and retention means must first be mounted on the inwardly projecting bearing journals be-cause of the impossibility of so mounting the cutters after thethree arcuate sections have been welded together.
After the bearing assemblies and cutters are mounted on the machined bearing journals, the three lugs are then placed in a welding jig and welded to each other to form the cylindrical bit body. After this welding has occurred a tapered thread is machined on the upper end of the bit, which tapered threaded end is commonly referred to as the "pin" end, and the bit is ready for use. The difficulties with this assembly method in manufac-turing tophole or large diameter bits is that because of the size of these bits, minor variations and tolerances in alignments of the three lug sections results in substantial final errors in the bit specifications and dimensions. The forged lug sections of the prior art bits are relatively rouyh and inaccurate and the machining of the mating surfaces likewise is c~lfficult to control to close tolerances. When the three lug sections are eventually welded together to form a single cylindrical structure wit.h cut-ter assemblies already permanently motmtecl thereon, most often the results are that the cutters are not only non-concentric about the rotational axis of the bit, but the cutters also extend dif-ferent distances downward from the pin end of the bit. Thus,one cutter may extend further downward than the other two and may provide almost all of the cutting action on the borehole bottom until that cutter is worn substantially to match the shorter two cutters. This tends to cause premature failure of either the 3~ bearings or the cutter shell on that one cutting assembly, which in turn will result in early failure of the bit. Likewise, ra-dial placement of the lucJs is diffic~lt to control and ma~ resultin the drill bit cutting under gage, which is undesirable because of the borehole being smaller than necessary and smaller than specified. Also, if one cutter extends radiall~ further outwar~
than either one or both o~ tl~e other cutters, a resulting effect could be " tracking" of the cutting teeth on the cutters and even-tual gyratiOIl or orbiting action of the bit about the rotational a~is thereby s~stantially eliminating the cutting efficienc~ of the bit.
l'he present invention elimina-tes these disadvantages found in the big diameter or top hole bits by providing a struc-ture that is much more easily assembled and in whicn tolerances can be closely controlled during assembly of the bit. Further disclosure is made of a method of assembli:ng the bit to provide extremely close tolerances in the radial and axial directions of the cutter assemblies. Also disclosed is 2 method of varying the offset of the cutter axes by relatively simple and inexpensive means during construction of the bit. The invention is achieved by utilizing a cast bit body which is formed in a single section and which has three platform areas formed tnereon for receiving three independent cutter assemblies which are then welded to the cast iron body. Each cutter assembly has a countersunk alignment point which is engaged by the hydraulic or mechanical alignment tool which forms a part of this invention. The alignment tool fixes the cutter assemblies in place on the cast metal body where-upon they are welded in place to form a highly accurate, closetolerance, large diameter tri-cone drilling bit.
Thus, according to the present invention, there is provided an oil well drilling bit for drilling large diameter boreholes which comprises an integrally formed cast metal body member having a pin end, a central bore passage, and a plurality of equispaced platform arms formed thereon. The platform arms -3 ~
s each have two different planes of machined alignment surfaces thereon in abutting relationship. A lug assembly is welded to each of the platform arms and has a lug member at one end and an inwardly projecting bearing ~ournal at its opposite end and further has a frustoconical cutter rotatably mounted on the bearing journal by bearing means. The body member and the lug members form one of at least two drill bits of significantly different diameters.
In a further embodiment, the invention contemplates an oil well tricone rolling cutter drilling bit for drilling top hole and large diameter boreholes and comprises an integrally formed cast metal body member having a pin end, a central bore passage, and three equispaced platform arms formed thereon. The platform arms each have a plurality of alignment surface means comprising two different planes for a lug assembly in abutting relationship while permitting verti-cal, horizonta:L, and skew adjustment during assembly and adapted to support a lug assemhly of a size selected from at least two different sizes. A lug assembly of a size selected from at least two different sizes are welded to each of the platform arms and has a lug member with a ley section at its attachment end and a bearing journal extending radially inwardly at its opposite end. The journal is adapted to support a cutter of a size selected from at least two different sizes, and the lug assembly further has a frustoconical cutter of a size selected from at leas-t two different sizes rotatably mounted on the bearing journal by bearing means. The b~dy member and the lug member form one of at least two differently sized drilling bits of significantly different diameters.
~ 3a ~
. . .
The invention also encompasses the novel method of manufacturing a plurality of sizes of oil well drilling bits and comprises forming an integral body member having a tapered end and a plurality of outwardly extending platform arms thereon, with each of the arms having a plurality of surfaces adapted to receive and support a cutter-supporting lug member in abutting relation thereto and permitting adjustable movement of such lug member in a vertical or horizontal direction during assembly.
Lug members are formed in a plurality of sizes operable to fit each of the platform arms, with each lug member having an attach-ment end and, at the opposite end, an inwardly projecting bearing journal. Rotatable cutter members are formed in a plurality of sizes and are constructed so that each size lug member fits two different sizes of the cutter members. A lug member of predeter-mined size is se:Lected for installation on each of the platformarms, and a cutter member is selected from the different sizes which fit the selected lug member. The selected cutter members are rotatably mounted on respective ones of the lug members with bearing means therebetween, prior to securing the lug members on the body member. Each of the selected lug members, with cutter members mounted thereon, is placed in operative engagement with at least two of the surfaces on respective ones of the platform arms. Each selected lug member is adjusted to a preselected position while maintaining operative contact with the platform arm surfaces. The lug members are clamped in the preselected position, and are welded to the platform arms while being main-tained in the preselected position.
BRIEF DESCRIPTION OF THE DRAWINGS
. . . _ Figure 1 is a side elevational view of the present invention showing the bit body and a typical cutter assembly in -3b-: ,-cross-sectional view Figure 2 is an axlal view of the cast metal body of the bit prior to the cutter assemblies being joined thereto. Figure 3 is a partial schematic drawiny taken in a radially outward direction of one cutter assembly illustrating its mounting on the cast bi-t body. Figure 4 is a block diagram illustrating the interchangeability of parts throughout the bit and the assembly method for obtaining four different bit sizes.
Figure 5 is a schematic axial view of the bit body illustrating the sweeping pattern of the nozzle system located thereon. Figure 6 is a schematic side view of the bit showing one cutter arm in place. Figure 7 is a close-up, broken-out view showing the align-ment method for assembling the bi-t. Figure 8 is a schematic view of the alignment system for assembling the cutter assemblies on the bit body.
DESCRIPTION OF ~HE PREFERRED EM3ODIMENTS
_, .
Referring now to the figures, and more particularly to Figure l, a tri-cone, rolling cutter drill bit according to the present invention is partially disclosed in cross-sectional view in Figure 1. Figure 1 illustrates the body and a typical lug assembly attached to the body. In normal procedure a tri-cone bit, according to this invention, would comprise a body and three of the leg assemblies as shown attached to the body in relatively equidistant relationship around the body; i.e., at approximately 120-degree intervals. In Figure 1, the tri-cone drill bit 10 comprises a single, integrally formed, steel body 11 having a central bore area 12 and a tapered pin section 13. Cen-tral bore 12 communicates through pin area 13 via pin bore 14. Three outwardly extending platforms 15 (only one shown) are integrally formed on body member 11 during the fabrication of the body member. Plat-form 15 generally comprises a relatively flat, upward-facing, moun-ting surface ~6 and a relatively flat, vertical, shoulder ~but-ment 17 joined with surface 16 to form an L-shaped mountiny plat-form for the lug assembly 18.
In one partlcular embodiment of the present invention, the body member 11 was formed in a single operation by means of casting from suitable steel alloy. By utilizing selective cast-ing techniques and e~tremely accurate casting, body member 11 can be obtained having a close-tolerance tapered section 13 and being close to tolerance on surfaces 16 and 17 of arm 15. In this par-ticular embodiment, tapered pin 13 was accurate enough to providealignment of the body member for final machining of surfaces 16 and 17 prior to attachment of lug assembly 18 thereto. The ma-chining of surfaces 16 and 17, because of the accuracy of the cas~
ting techniques, generally nèeds only a minor bit of machine work to smooth up the area for abutment of leg assembly 18~ Alterna-, tive to machining surfaces 16 and 17 off of the alignment with unflnished tapered pin 13 is to machine the final threaded por-tion on the external surface of pin 13, (which threaded surface is utilized to interconnect the drill bit with the drill string), and then threading the tapered end 13 into a female threaded alignment jig before machining surfaces 16 and 17.
The lug assembly 18 comprises, a unitary lug member 19 which in this embodiment was formed in a forging operation.
Lug 19 comprises leg section 20 having a L-shaped end with hori 25 zontal surface 21 and vertical surface 22. Surfaces 21 and 22 preferably are machined on leg section 20 to match surfaces 16 and 17 and provide proper alignment of leg assembly 18 on member 11~ At the upper end of lug member 19 (as shown in Figure 1), a compound bearing journal 23 is formed on the lug member during the forging operation and ls final-machined to provide roller bear-o~;
ing surfaces 24 and 25. ~lso a ball bearing race 26 is formed on journal 23 as well. as a thrust bearing recess 27. Alternative-ly, roller bearlng races 24 and 25 could be replaced with fric-tion bear;.ng surfaces should the bit manufacturer wish to utilize 5 sleeve-type frlction bearings in place of the roller bearings as disclosed herein.
A plurality oE roller bearings 28 are located in roller bearing recess 24 to substantially encircle bearing jour-nal 2 3 and provide rotatable contact with the cutter mounted there-10 on. Likewise, a set of smaller roller bearings 29 are locatedi.n roller bearing recess 25. A plurality of ball bearings 30 are located in ball bearing race 26 to encircle bearing journal 23.
A small, flat, circular thrust disc 31 is located in thrust re-cess area 27. Thrust disc 31 may be comprised of any suitable 15 bearing material such as copper, steel or any of the softer metals such as lead, s ilver, indium; or may be formed of any combinatlon of these elements. Roller bearings 28 and 29 and ball bearings 30 are preferably formed of a hard, tough metal alloy such as steel, which i.s suitable for receiving high loads without galling or 20 spalling. Such alloys are well known in the art and not disclosed herein.
, Each of the three lug members 19 are preferably lo-cated on platorms 15 of body member 11 and attached thereto by welding as shown in Figure 1 at 32. Welding is performed 25 along a weld groove 33, which is formed along the outer edge of leg section 20 around surfaces 21 and 22. The particular weld configuration may be seen more clearly in Figure 3 where like numbers represent identical elements.
.. .. .. .. . .... ...... .... . . ........ .. .. .. . .. . . . .
s Each lug member 19 also has rotatably mounted thereon a generally frusto-conical cutter 34 having a plurality of cut-ting elements or teeth 35 protruding outwardly therefrom. In this particular embodiment the cutter 34 ls formed by casting of a high-strength, tough, steel alloy and the teeth 35 are integrally formed thereon. These teeth are generally wide and flat and represent a general chisel shape. Alternatively, the cutters may be formed by forging a frusto-conical cutter blank of suffi-cient size to include the integral teeth. After the forging opera-tion material is machined away to leave the protruding chisel-shaped teeth.
The embodiment shown in Figure 1, as mentioned previ-ously, is a tri-cone bit, although only a single lug assembly is shown for simplification reasons. The illustration in Figure 1 does show the tooth profile of all three cutters of the bit super-imposed upon the single cutter 34. The illustration of cutter 34 is that of the number two cutter on the bit. The teeth of the number one cutter are shown at 36, and the teeth of the numb~r three cutter are shown at 37. Thusl while it was not neces-sary to show all three of the lug assemblies 18 in order to fullydisclose the tri cone bit since each of the cutters 34 have a dif-ferent tooth arrangement to allow for better bottomhole coverage and better intermesh of the teeth without interference betweer.
adjacent teeth, the profiles of the three cutters are combined to illustrate the total bottomhole tooth coverage. Figure 7 bet-ter illustrates the individual cutter profiles showing the indi-vidual spacing relationships of the teeth for each cutter.
One particular feature of the present invention is illustrated in Figure 1 by the lines drawn in phantom thereon.
In the lug member 19, an alternate surface 38 is shown drawn in )s phantom. Likewise, in cutter 34, an alternate ~aye surface 39 is shown in pllantom. These alternate surfaces will be explained in more detail with reference to the description relating to Figure 4~ ~
S In addition to the attacllment of lug assembly 18 to body member 11 on platform 15, the body member has additional elements as disclosed in Figure 1. A plurality of fluid jetting nozzles are located in sufficiently sized openings formed through the central upper porti.on 40 of body member 11 communicating with central bore 12. ~he nozzles comprise a single center nozzle 41, a plurality of intermediate nozzles 42, and a plurality of outer nozzles 43. The angular orientation o~ the intermediate nozzles 42 is shown in relation to a vertical axis Vl drawn ~rough the center of the nozzle 42. One nozzle in this embodiment was placed at an angle of five degrees, the second intermediate nozzle was angled at fifteen degrees, and the thlrd intermediate nozzle was angled at twenty-five degrees from axis Vl. Likewise, the angu-lar displacement of the outer nozzles,43 can be shown with res-pect to a vertical axis V2 drawn through the center of outer noz-zle 43. In this particular ernbodiment, nozzles 43 are angled at 25 degrees from axi.s V2.
P~eferring now to Figure 2, a top view looking down the central rotational axis is ill,ustra-ted showing the body mem-ber 11 prior to assembly of the lug assemblies 18. In Figure 2 the cen-ter nozzle 41, the intermediate nozzles 42 and the outer nozzles 43 are shown in relationship to each other. The outer nozzles 43 are located in recessed areas or valleys 44 formed in body member 11. The angular placement of the intermediate nozzles 42 is i.ndicated by the phantom lines extending downward 3~ therefrom which illustrate the location of the nozzle bodies .
i. -8-)S
inside their openin~s which h~ve been cast or machined into body member 11. Nozzles 41, 42 and 43 may be retained in me~ber 11 by any of se~eral alternate methods such as threading, press-fitting, welding and retention by snap rings.
Figure 5 is a schematic diagram showing a top axial view of body member 11 after the h~draulic nozzle system has been installed but prior to attachment of the lug assemblies 18. The schematic diagram of Figure 5 illustrates the spiral or sweep pattern of the nozzles as installed. The seven nozzles thus arranged allow the cleaning of different sections of the bit and the borehole, starting with the center nozzle and moving radially outward towards the outer nozzles, which are directed to the gage area being cut in the borehole.
Referring now to Figure 3, a radial view of one lug member 19 is disclosed welded in place on body member 11. The cutter 34 has been omitted in order to better illustrate the method of welding the member l9 to member 11. In this embodiment a weld channel has been formed by beveling the outer edges of the lower end 20 of lug member 19 so that weldment may be formed between leg section 20 and pla-tform 16 and 17. The weldment i5 illustrated in Figure 3 at 32.
Referring now to Figure 7, the three typical cutters utilized on the bit of this embodiment have been cross-sectioned and laid out in a profile to illustrate intermesh of the teeth amongst the set of three cutters for one bit. Likewise, Figure 7 illustrates the placement of the fluidic nozzles with respect to the cutters to show the flow of drilling fluid therebetween.
It should be noted that because of the three-dimensional aspect of the cutter placement, the three-dimensional cutter profile in-dicated in Figure 7 must involve splitting one of the cutters in half to more realistically de~ine the -three-dimensional relation ship in a two-dimensional, planar drawiIIg. From Figure 7 it can be seen that the nozzle system is primarily directed to the in-ter-mesh areas between the cutters to better sweep cut-tings Erom the borehole face as they are broken out. It is preferred that no nozzle be directed against a cutter shell because of the inherent problems arising from fluid erosion when the nozzles are directed against the cutter bodies.
Figures 6 and 8 illustrate in schematic diagram the system for assembling the lug assemblies on the body member. The system primarily consists of a relatively large, flat base plate 45, having three interspaced sliding aligriment arms 46 located thereon, which alignment arms are arranged to be brought into contact with the radially outward portion of leg section 20.
The alignment arms 46 are spaced at intervals of 120 degrees around plate 45 from each other when ~he embodiment of the inven-tion is that of a trl-cone bit. Base plate 45 has a tapered open-20 ing 47 for receiving tapered pin section 13 of body member 11.
Pin opening 47 may be either internally threaded to match the ex-, ternal threaded portion of pin 13 or may be smooth-walled to re-ceive either the threaded pin end 13 or could be used to receive pin end 13 prior to the threads having been machined thereon.
In either instance, opening 47 preferably is dimensioned to snugly fit pin end 13 and secure body member 11 in a rigid, stationary position to accurately locate lug assemblies 18 thereon. The align-ment arms ~6 are relatively rigid and preferably allowed movement only in a radially outward and inward direction. Movement of arms 46 can be controlled by means well known in the art such as elec-trical, hydraulic, mechanical or pneumatic.
Figure 6 is a schematic illustration of a portion of Figure 8 broken out and enlarged to better illustrate the align-ment technique for aligning lug member 19 on platform 15. The end of each alignment arm ~6 is formed with a particular geomet-ric configuration such as a right circular cone 47 e~tending ra-dially inward towards the lug member 19. Likewise, a complemen-tary indentation ~8 is formed in lug member 19 to receive the geo-metric end 47 of arm 46. When such configuration as a conical end 47 and a conical indentation 48 are used, it can be seen that movement radially inward by arm 46 when it contacts the indenta-tion 48 will locate member 19 in an identical position each andevery time. Should a misalignment occur, the force of arm 46 mov-ing inward into opening 48 will move member l9 until the geomet-ric end 47 is completely embedded in socket 48, thereby providing proper alignment. ~t that time should there be spacing between lug member l9 and platform 15, a requisite number of metal shim plates 49 may be inserted prior to ~elding of lug member l9 on platform 150 It should be noted that although Figure 8 illustrates a single lug member being attached to the body member, all three such members may be attached simultaneously for optimum alignment of the lug assemblies. It should also be pointed Ollt that the three lug assemblies 18 are completely assembled, including all bearings, seals and cutters, prior to attachment to body member ll because of the impossibility of attaching the cutters after the lugs l9 have been welded to the bodyO The lug assemblies 18 have been simpli~ied in Figure 8 to more cl~arly illustrate the method o assembly, but in the preferred embodiment, the three lug assemblies 18 in complete assembly form are attached to body member 11 simultaneously by the use of welding techniques in con~
junction with alignment system 45.
Figure 4 illustrates a schematic block diagram show-ing the versatility of the present invention in forming different . . .
sizes of bits using interchangeability of various components~
~or instance in ~his particular embodiment, a single body casting ll can be utilized in forming four different diameter bits. This body casting can be used in a 20-inch bit, 22-inch bit, 24~inch bit and 26-inch bit. In order to manufacture these four sizes of bits, two different lug members 19 are utilized -- l9a and l9b.
Lug member l9a is utilized to form a 20-inch bit and a 22-inch bit. These two bits utilize -the same body casting and the same lug, but use different size cutters 34a and 34aa. Likewise, the two larger bits r the 24-inch diameter and the 26-inch diameter, each use the same body casting ll and the same lug l9b, but like-wise use two different cutters 34b and 34bb. Thus, the manufac-ture of four different size bits ranging from 20-inch diameter to 26-inch diameter requires only a single type body member, two different types of lugs and four different size cutters.
In addition to this tremendous fle~ibility and effi-ciency in assembly, further optimum savings can be obtained by utilizing~lug members 19a and l9b, which are substantially iden-tical except in on]y a small particular area. For instance, re-ferring back to Figure 1, the lug member l9a of Figure 4 can beseen in Figure l is defined by the phantom line 38. The larger lug member 19~ is defined by the outer line of member 19 rather than the phantom line 38. Similarly, optimum efficiency in manu-facture of cutters 34 can be achieved by casting the individual cutters and utilizing casting shells that are identical in many respects.` The smaller cutters 34a and 34aa are defined by the phantom lines 39 whereas the larger cutters 34b and 34bb are de-fined by the outer lines along the gage surface rather than thephantom lines 39. Thus, by merely changing the gage portion of the cutters at 39 and by changing the radial outward shoulder areas at 38 of the lugs and also by the use of a single body member 11, S
four different 5ize bits can ~e manufactured basically using sub-stantially the same amount of tooling and casting equipment as would normally be required in a single diameter bit.
With the great advancements in casting techniques re-cognized today, such as the investment casting and centrifugal casting methods, the cutters 34 having the integrally formed teeth provide a cutter of identical quality to the conventional method of machining the cutters. Because of the accuracy of modern cast-in~ techniques, the cutter dimensions and the teeth configurati~ns are acceptable in the casting and need no machining except in the minor bearing areas internally in the cutter. Preferably, the lug members 19 are forged and machined in the bearing areas be cause of the strength requirements and the simplicity in forging this relatively uncomplicated shape. The body members 11 prefer-ably are cast in a single operation to form a single, integral body section which ls relatively inexpensive to cast and in which the final casting has substantially all of the external dimensions within acceptable tolerances. l'he only remaining machining is the shoulder areas lS and in some cases the nozzle bores for the 20 fluidic nozzles 41, 42 and 43. In addition the threaded pin end 13 is machined after the casting. The casting of body member 11 utilizing the known casting techniques is accurAte enough that the alignment system 45 can be utilized with the cast pin end 13 even prior to machining of the pin threads thereon.
SU~ARY OF TEIE INVENTION
The present invention is directed to a multi-cutter, rolling cone drill bit for use in large diameter boreholes, particu-larly the initial borehole at the top of the drilling operation.
mhese bits are generally of the three-cone configuration and are termed, "top hole" bits. The present invention discloses a top hole bit of extremely accurate external dimensions and a method of manufactu~ing this bit utili~ing fle~ibility in part selection and interchangeability of parts to provide various sizes of bits from con~on components. The present invention utilizes an in-te-gral cast body rather than the three arcuate segments of the prior art bits. The invention utilizes two sets of forged lugs to pro-vide four sizes of bits.
Likewise, this invention utilizes cast metal cutters10 rather than machined cutters with four different cutters for the four bit sizes. The two smaller size cutters differ only in the small gage area along the large part of the cone. Also, the two larger diameter bits utilize two different cutter configurations which differ from each other only in the small area added along the gage of the cutter. In addition to these features, the pre-sent invention discloses a spiral sweep nozzle arrangement uti-lizing seven nozzles in a fluidic system which is particularly advantageous in cleaning the entire bottom of the borehole as itis being drilled.
Furthermore, an additional feature and advantage of this invention i5 the ease and accuracy of the as~embly method.
The body member is securely attached in a base plate or table to which are slidably attached three alignment armC having geomet-rical alignment ends for matching engagement in the lug assemblies.
It should be noted here that in addition to providing close align-ment of the lug assemblies, an easy method of introducing skewed axes into these bits reveals itself with the present alignment system. For instance, if a particular skew dimension in the jour-nal axis is desired, the correlative amount of offset in the align-ment indentation 48 can be introduced into each of the lugs such .. .. . . . . ....
S
that the alignment arm ~6 properly positions each luy to obtain the desired a~is skew. Thus, the bi-t axis s]~ew can-be controlled very closely by simply relocating the aliynment indentations 48 in each of the lugs. Likewise, proper axial alignment, i.e., height of the cutters above the body men~er, is easily obtained by the alignment system 46 in conjunction wi-th -thin metal shims ~g.
In addition to this extremely close control over the height measurements of the three cutter cones, which height con-trol allows a proper weight and wear distribution on each of the three cones, the radial measurements of the three cutters can be held to close tolerances by the same shi~ning methods along sur-face 17. Thus, the cutters, b~ proper shimming on surfaces 16 and 17, will end up properly balanced with respect to load and each sharing proportionately in the cutting of the gage diameter.
This greatly reduces rapid wear and failure of the cutter assem-blies and provides proper gage cutting action. Thus, it can be seen that the present invention involves large bits and their meth-od of manufacture, which bits offer advanced techniques for ease of assembly and for close control of critical tolerances.
Although certain preferre~ embodiments of the inven-tion have been herein descrihed in order to provide an understand-ing of the general principles of the invention, it will be appre-ciated that various changes and innovations can be effected in the described large diameter, tri-cone drilling bit without de-parting from these principles. For example, it is obvious that one could alter the number of lug assemblies provided in the bit to include more than the three assemblies illustrated. Also, rath-er than utilizing cut-ters which are formed by casting, one could utilize machined cutters instead. The invention, therefore, is declared to cover all chan~es and modifications of a specific ex-ample herein disclosed for purposes of illustration which do not constitute departures from the spirit and scope of the inventi.on.
: -16-
Claims (7)
1. An oil well tricone rolling cutter drilling bit for drilling top hole and large diameter boreholes, said bit comprising:
an integrally formed cast metal body member having a pin end, a central bore passage, and three equispaced platform arms formed thereon;
said platform arms each having a plurality of align-ment surface means comprising two different planes for a lug assembly in abutting relationship while permitting vertical, horizontal, and skew adjustment during assembly and adapted to support a lug assembly of a size selected from at least two different sizes;
a lug assembly of a size selected from at least two different sizes welded to each of said platform arms and having a lug member with a leg section at its attachment end and a bearing journal extending radially inwardly at its opposite end; said journal being adapted to support a cutter of a size selected from at least two different sizes; said lug assembly further having a frustoconical cutter of a size selected from at least two different sizes rotatably mounted on said bearing journal by bearing means; and said body member and said lug member forming one of at least two differently sized drilling bits of significantly different diameters.
an integrally formed cast metal body member having a pin end, a central bore passage, and three equispaced platform arms formed thereon;
said platform arms each having a plurality of align-ment surface means comprising two different planes for a lug assembly in abutting relationship while permitting vertical, horizontal, and skew adjustment during assembly and adapted to support a lug assembly of a size selected from at least two different sizes;
a lug assembly of a size selected from at least two different sizes welded to each of said platform arms and having a lug member with a leg section at its attachment end and a bearing journal extending radially inwardly at its opposite end; said journal being adapted to support a cutter of a size selected from at least two different sizes; said lug assembly further having a frustoconical cutter of a size selected from at least two different sizes rotatably mounted on said bearing journal by bearing means; and said body member and said lug member forming one of at least two differently sized drilling bits of significantly different diameters.
2. The oil well drilling bit of Claim 1 wherein said plurality of alignment surface means on said platform arms comprises a vertical machined surface and an adjacent horizontal machine surface.
3. The oil well drilling bit of Claim 1 or Claim 2 wherein each said lug assembly further includes an alignment indentation in each said lug member.
4. The oil well drilling bit of Claim 1 or Claim 2 wherein said cutter comprises an integral cast metal cutter with cast metal teeth protruding therefrom.
5. The oil well drilling bit of Claim 1 or Claim 2 further comprising a fluid nozzle system containing a plurality of jet nozzles on said body member communicating with said central bore passage and arranged in an angular spiral pattern to sweep a borehole face with fluid jets.
6. The oil well drilling bit of Claim 1 or Claim 2 further comprising shim means between said lug assemblies and said alignment surface means arranged to provide said vertical, horizontal and skew adjustment among said lug assemblies with respect to said body member.
7. The oil well drilling bit of Claim 1 in which said platform arms each includes an L-shaped machined alignment surface thereon;
each said lug assembly includes a cast steel frustoconical cutter rotatably mounted on said bearing journal by bearing means;
a spiral sweep nozzle system comprising a plurality of jet nozzles on said body member at the end opposite said pin end, arranged to communicate fluidically with said bore passage and adapted to spray a fluid sweep against a borehole face being drilled.
each said lug assembly includes a cast steel frustoconical cutter rotatably mounted on said bearing journal by bearing means;
a spiral sweep nozzle system comprising a plurality of jet nozzles on said body member at the end opposite said pin end, arranged to communicate fluidically with said bore passage and adapted to spray a fluid sweep against a borehole face being drilled.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000394154A CA1182105A (en) | 1982-01-14 | 1982-01-14 | Method of manufacturing large diameter oil well drilling bit and large diameter oil well drilling bit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000394154A CA1182105A (en) | 1982-01-14 | 1982-01-14 | Method of manufacturing large diameter oil well drilling bit and large diameter oil well drilling bit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1182105A true CA1182105A (en) | 1985-02-05 |
Family
ID=4121819
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000394154A Expired CA1182105A (en) | 1982-01-14 | 1982-01-14 | Method of manufacturing large diameter oil well drilling bit and large diameter oil well drilling bit |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1182105A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5016719A (en) * | 1990-01-24 | 1991-05-21 | Western Rock Bit Company Limited | Rotary cone type rock bits |
| GB2454068A (en) * | 2007-10-12 | 2009-04-29 | Smith International | Rock bit with hydraulics configuration |
| US8091654B2 (en) | 2007-10-12 | 2012-01-10 | Smith International, Inc | Rock bit with vectored hydraulic nozzle retention sleeves |
-
1982
- 1982-01-14 CA CA000394154A patent/CA1182105A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5016719A (en) * | 1990-01-24 | 1991-05-21 | Western Rock Bit Company Limited | Rotary cone type rock bits |
| GB2454068A (en) * | 2007-10-12 | 2009-04-29 | Smith International | Rock bit with hydraulics configuration |
| GB2454068B (en) * | 2007-10-12 | 2010-06-16 | Smith International | Rock bit with hydraulics configuration |
| US7913778B2 (en) | 2007-10-12 | 2011-03-29 | Smith International, Inc. | Rock bit with hydraulic configuration |
| US8091654B2 (en) | 2007-10-12 | 2012-01-10 | Smith International, Inc | Rock bit with vectored hydraulic nozzle retention sleeves |
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| MKEX | Expiry |