US2160852A - Rock bit - Google Patents

Description

June 6, 1939. L A GAUTHEY v 2,160,852

ROCK BIT Filed April 12, 1937 2 Sheets-Sheet l 'e 1 #im 1 "un w* 40 /Zdlad N June 6, 1939.

l.. A. GAUTHEY ROCK BIT Filed AprLlWl, 1937 Patented June 6, 1939 1 'UNITED 'STATI-:s

PA1F.1-1'1* OFFICE alumaocxarr- This invention relates to well drilling tools and has particular reference to a rock bit for use in the rotary method of well drilling. A general object of this invention is'to provide a practical, improved, and very effective rollerl blt or rock bit.

Another object of this inventicn is to provide a rock bit for use in the rotary method of well drilling that is very rapid in its operation or its penetration of the earth formation.

Another object of this invention is to provide a roclr bit in'which the cutters are arranged and related to have a chipping and breaking down action on the formation as distinguished from` which have mation that arev easily and rapidly broken down and cut away by the said other cutters thereby increasing the rate of penetration of the hit.

Another object of this invention is to provide a well bit of the character mentioned in which the roller cutters have relatively short cutting teeth whereby heavy feed pressuresare applied to the cutting teeth per lineal unit of length without exerting increased feed pressure on the bit. The roller cutters of the bit provided by the present invention being relatively short ornsrrow in comparison with the cutters of rock bits now in general use are much more rapid in their penetration of the earth formation.

Another object of this invention is to provide a rock bit of the character mentioned in which the pilot roller cutters are spaced apart to assure the independent rotation of the cutters, to saure the proper `flushing of the cutters and to form spaced annular channels or cuts in the earth formation which center the bit and which provide: or leave upstanding ridges of earth formation -that are rapidly broken down by the trailing and higher roller cutters.

Another object of this invention is to provide a. roller bit or rock bit in which the outer cutters. for cutting the well bore to gauge act on the formation in a plane above the inner cutters and.' therefore, are relieved of an appreciable amount of the cutting action at the bottom of the bore and the resultant wear. The outer cutters of the bit of the present invention act inplanes above the planes of action 4of the inner cutters and, therefore, are only required to cut the bore to gauge and to break down and shatter the upstanding ridges left by the pilot cutters or'A inner cutters.

Another object of this invention is to provide a rock bit embodying means for handling the circompanying drawings, in which:

Fig. l is aside elevation of the improved rock bit provided by this invention. Fig..2 is an enlarged vertical detailed sectional view of the bit. Pig. 3 is a fragmentary vertical detailed sectional view of the bit taken in a plane at right angles to the plane of sectioning oi Fig. 2. Fig, 4 is an enlarged fragmentaryl vertical detailed sectional view illustrating the mounting for the central cutter. Fig. 5 is a transverse detailed sectional view taken as indicated by line 5 5 on Fig. 2 illustrating the principal cutters in broken lines to show the relationship between the fluid discharge ports and the cutters. Fig. 6 is an enlarged fragmentary side elevation of one of the body legs illustrating the means for. locking the cutter pins against rotation. Fig. 'I is a fragmentary vertical detailed sectional view taken as indicated by line 1--1 on Fig. 6 and Fig. 8 is a schematic or diagrammatic view illustrating the action of the cuttersv of the bit in the well bore.

The improved roller bit or rock bit of this invention includes, generally. a body 'I0 adapted' to be connected with a rotary well drilling string, sets of pilot cutters il land ill rotatably supported on the body I Il to make annular groovesv A and B in the earth formation at the bottom of the .well bore, and sets of roller cutters I! and I2* supported on the body i0 to act on the formatioltbetween the grooves A and Band around the groove A to cut the well bore to gauge.

is provided on the upper end of the body I0 to facilitate its connection with the string. In accordance with the invention the bit body Il is provided with setsor pairs of depending legs il and II arediametrically oppoeiteand are spaced sul: stantiallyL i'rom the legs I 4. The inner sides i2 oftheelegs Il are inclined downwardly and outwardly'relative to the vertical axis of the. body I0. 'ihe'exteriororperipheryoithebody Ilmay have vertically extending ribe- I1 joining the legs I4 and I2 to strengthen tbebody structure. In

accordance 'with the invention the legs I4 are longer than the legs i2,that is, the lower ends of the legs I4 are in a plane spaced below the lower ends or the legs Il. Reinforcing webs I2 may connect the upper inner parts ot the legs I4 with the lower end of the body` Il. The bit body Il further includes a substantially central web I2. The web I2 projects downwardly from the lowerend of the body Il as illustrated in the 'I'he sets of cutters Il and II` are provided to act on the earth formation at the bottom of the well bore W in advance of the cutters I2 and I2* tomaketheannularcutsorgroovesAandBas iilustratedin Fig. 8. While I have termed the .cutters II and- Il* pilot cutters, they may also.

be termed inner cutters, asl they act on the earth formation entirely within the perimeter of the bore W. The inner cutters or pilot cutters II and III are in the nature o! roller cutters sup ported to rotate about their individual axes and. to cut into' the earth formation by a crushing and rolling action.

There are preferably two sets of cutters II and IIn eachsetbeinglocated between aleg I4 and the opposing surface 22 of the body web I2. Thenumber of pilot cutters embodied'in each set may-be varied in accordance with the size of the bit. In the simple form of the invention illustratedln the drawings there are two Pilot cutters I-l and IIl provided in each set of cutters. The cutters II and Il* are truste-conical. that is, they have pitched or inclined peripheries'. Axially`- extending cutting teeth 22 and 22 are provided on the respective peripheries of the cutters II and II. The cutters Il and Il* arearranged with their small ends facing inwardly relativetovthe central vertical axis of the body III. The pilot cutters IIandII are graduated insize,thatis. thecutters Ilearesmallerindiameter than the cutters II and are-.spaced inwardly 'from the cutters II with rpect to the center of the bit. The cutters Il and IIl or the sets of cutters are in the samerespective positions relative to the central vertical axis of the bodyill sothat both the cutters lloperate in andform the groove A and both cutters I I'A oper'- ate in and form the groove B. Asbest illustrated inFig. 8 the cut or grooveAis-spaced'some distance inwardly from'the perimeter of the well boreWand the cutBformedbythecutters II* v` is spaced between the groove A and the center of the well bore. v

The means for rotatably supporting the pilotV openings 22 inthe web I2. In the preferred conv struction illustrated the cutter supportingpins 24 aresubstantially horisontal and are radial relative to the vertical'axis o! thebob I2'. The .pins 24 may be simple, cylindrical parts of unlformdiameter. II andil'wrero` aieosa tatably supported on the pins 24 by suitable roller bearings 21 and 21* respectively. Suitable thrust .washers 22 are interposed between the outer ends of the cutters II and the inner sides ofthe les! I4.

ends of the cutters II* and the surfaces 22 of the web I2. Washers 22 may be provided on the pins 24 to space the adjacent cutters Il and II and their bearings 21 and 21. The washers 2lmaydirectlybearonthepins24 andifdesired may be in the form of star washers to rotate at will. The opposing ends of the cutters II and- IIl may be provided with bosses or hubs,

as illustrated, so that the cutters have more extensive engagement on the bearings 21 and 21a.

l'he invention provides novel means for locking the cutter carrying pins 24 against unthreading. Diametric dove-tailed grooves 2| are provided in the outer ends of the pins 24.- Similar grooves 22 are provided in the outer sides of the legs I4 to register withthe grooves 2l. Dovetailed keys 22 are driven into the grooves 22 and 2| to positively lock the pins 24 against unthreading when the pins have been properly threaded in piace.` The grooves 2I in the'ends of the pins 24 may be utilized as screw driver slots to facilitate the threading oi the pins. 'Ihe ends of the keys 22 may be lightly welded to the legs I4 or the outer vportions oi the` grooves 22 may be closed with welding to prevent the accidental displacement of the dove-tailed keys 22.

`The invention preferably includes a cutting means for acting on the central portion oi' the bore `within the groove B formed by the cutters Il. 'Ihis central cutting means may include a Similar thrust bearings 22 mayl be provided on the pins 24 between the inner-fdisc-like roller cutter 2,4. The cutter 24 is rotatably supported in a pocket 2l'in the lower end of the body web I2. and is adjacent but offset from the central vertical axis of the bit. The means for rotatably supporting the cutter 24 in the pocket 25 mayr include a reduced extension rotatably supported on the pin extension 22 through a. suitable roller bearing 22. The opposing ends oi the pins 24 may protrude into the pocket 22 and may act as thrust receiving surfaces at the opposite ends of the cutter 24. The

v cutter 24 projects downwardly beyond the lowerI end of the pocket 2l and has pitched peripheral cutting teeth 22 for acting on the formation. The cutter 24 being adjacent the center of the groove C as illustratedin Fis. 8.

'nie cutters I2 and I2* are rotatably supported at the lower end of the bit body I2 to act on the earth formation in a plane or planes abovethe lower ena of the cutters II and Ile and therefore trail or follow the cutters' II and I I e in their action on the earth formation. The cutters I2 and I2* are in the nature of roller. cutters and .well bor has a rolling and scraping action'in e its engagement with the earth formation, to cut away the formation at a substantially central are rotatably supported in sets or pairs between .the legs Il and the body web I2. The cutters I2and I2arearrangedinsetsorpairseach including a cutter I2 and a cutter I2, The cutters I2 and |1215 ofeach set are co-axial and are rotatable about downwardly and 'inwardly inclinedaxes. lliecuttersI2aresupporteiatal greaterdistancefmmthecentralaxisofthebit than the cutters -I2i and, therei'e.are comid-l vit erably larger in diameter than the cutters I2. The cutters I2 and I2a are thin or short with relation to the outer roller cutters employed on typical rock bits. In practice the cutters I2* may be somewhat thinner or shorter than the cutters I2. The cutters I2 and I2 are frustoconical having their peripheries pitched or inclined relative to their axes of rotation. Suitable peripheral cutting teeth 40 and 40 respectively are provided on the peripheries of the cutters I2 and |2. In accordance with the invention the pitch or inclination of the axes of rotation of the cutters I2 and I2a is such that the edges of the teeth 40 and 4|)n are inclined downwardly and outwardly when they come into contact with the earth formation at the bottom of the well bore. Thus the surfaces at the bottom of the'bore acted-on by the teeth 40 and 40 are inclined upwardly and inwardly relative to the axis of the well bore W and the cooperation of the teeth with these conical or inclined surfaces center and stabilize 'the bit.

The cutters I2 'act on the ridge D of earth formation between the'groove A and the wall of the bore W and serve to cut the bore to gauge. The lower portions of the cutters I2 project downwardly and outwardly beyond lthe lower ends of the legs I5 to act on the earth formation. It is to be particularly noted that the teeth 40 of the cutters 'I2 act on the formation in a plane above the plane of action of the cutters II and IIn and, therefore, rapidly break down and cut away the ridge D which is unsupported at its inner side due to the presence of the groove A. The outer ends of the teeth 40 are preferably bevelled oi to be substantially vertical when the teeth engage the formation at the bottom of the bore to properly cut the well bore W to gauge to pass the bit with proper clearance.

The cutters |2a act on the earth formation at the upper surface of the ridge E occurring be-y tween the annular grooves A and B. The teeth 40*L of the cutters I2 act on the earth formation in substantially the same plane as the cutters I2 having their plane of action above the plane of action of the cuttersII and IIa. The inner cutters I2?A act to quickly break down and cut away the ridge E as the ridge is unsupported at its inner and outer sides due to the presence of the grooves A and B. It is believed that it will be understood how the cutters I2 and |2u are operable to rapidly break down the ridges D and E respectively with a minimum of drilling pressure and thereby greatly increase the rate of penetration of the bit.

The means for rotatably supporting the cutters I2 and I2n on the body I0 too'perate in the manner described above may be varied somewhat Without departing from the spirit of the invention. In the form of the invention illustrated in the drawings the means for rotatably supporting or mounting the cutters I2 and I2a include pins 42 passed inwardly through downwardly and inwardly inclined openings 43 in the legs I5. Reduced extensions 44 are provided on the linner ends of the pin 42 and are threaded lin sockets 45 in the body web I9. Annular shoulders 45 occur onthe pins 42 at the bases of the reduced extensions 44 andy these shoulders are in spaced opposition to the surfaces 2| of the body web I9. The cutter supporting pins 42 maybe locked against unthreading in the same manner as the pins 24. Dove-tailed keys 41 are arranged in dove-tailed grooves in the outer sides f the legs I5 and the outer ends of the pins 42 to prevent rotation and unthreading of the pins. The key receiving grooves in the outer ends of the pins 42. may be employed as screw driver slots to facilitate the threading in and removal of the pins 42.

The cutters I2 and I2* of each set or pair of cutters are rotatably supported on the pins 42. In the preferred arrangement suitable roller bearings 48 rotatably mount the cutters I2 and I2B on the pins 42. Spacing washers 49 may be provided on the pins 42 between the bearings 48. The opposing sides of the cutters I2 and I2*l may have hubs 50 whereby the cutters have extensive cooperation with the bearings 48. Spacing washers 5| may be recessed in the hubs 50 to act as thrust washer between the cutters. Thrust washer 5,2 are provided on the pin extensions 44 and are clamped between the shoulders 46 and the surfaces 2| of the body web IS. The washers 52 take the inward thrusts from the cutters I2. Suitable thrust washers 53 are arranged on the pins 42 between the outer ,sides of the cutters `I2 and the inner surfaces I6 of the legs I5. The cutters I2 and I2ll mounted as just described may independently rotate about their own axes to act on the ridges D and E of the earth formation as described above.

The invention provides particularly effective meansl for flushing the cutters II and Il and I2 and I2n and the bit generally to clear the cutters of mud, etc. and to prevent the bit from becoming balled up. A central circulation passage 54 vextends downwardly into the body I0 from the upper end of its pin I3. The passage 54 may be ofi substantially the same capacity as the fluid.

passage in the drill collar of the drilling string. Fluid discharge ports 55 are provided in the body Il to discharge streams of circulation fluid downwardly against the sets of cutters I and I The ports 55 extend downwardly and outwardly from the lower portion of the passage 54` to the lower end of the body I 0. In accordance with theinventionthe ports 55 are of substantial iluid capacity to discharge substantial volumes of iluid at a low velocity. It is a feature of the invention that the streams of fluid discharged from the ports 55 impinge against the cutters I| and II'l at the rear of their axes of rotation relative to the direction of rotation of the bit.l Fig. 5 of the verse axes of the ports 55 preferably extend outwardly and slightlyl rearwardly relative lto the4 planes X of the axes of rotation of the cutters II and IIlso that the 'streams of iluid impinge against substantially corresponding parts of the graduated cutters. This relationhip between the ports 55 andthe planeXofthe axes of the cutters I| and I I is best illustrated in Fig.'5. The large streams of fluid of low velocity discharge from theports 55 against thev cutters and IIa at points behind their axes of rotation tolfullyl flush the cutters of mud and cuttings 'without injuring the cutters.A The solid matter in the fluid issuing from the ports 55 at a` relatively low velocity does not abrade or cutinto the cutters to destroy their cutting.v parts.- The fluid discharged from the elongate ports 55 fully washes about the cutters II and Il and the adjacent legs I5 to prevent mud from accumulating on the same.

The flushing means further includes ports 56 in the body I extending downwardly from the passage 54 to the lower end of the body. The ports 56 are provided to discharge streams of fluids against the cutters I2 and |28. The ports 56 are located to discharge the streams downwardly behind the axes of rotation of the cutters I2 and I2a relative to the direction of rotation of the bit. This relationship is clearly illustrated in Fig. 5 of the drawings where Y represents the vertical plane of the axes of rotation of the cutters I2 and I. The ports 56 are shaped to discharge broad streams of fluid to flush the adjacent cutters I2 and I2a of each set. The ports 56 are elongate in transverse cross section having their longest transverse axes extending in a general radial direction with respect to the central axis of the bit and extending outwardly and slightly rearwardly with respect to the plane Y. The ports 56 formed and located in this manner operate to discharge broad streams of fluid at a low velocity to impinge against the cutters I2 and I2a throughout their lengths at points behind the vertical plane Y of the axes of rotation of the cutters. The streams of circulation fluid from the ports 56 flush between the adjacent cutters I2 and I2a and between the cutters I2 and the legs v Hand between the cutters I2a and the web I9 to prevent the cutters and the adjacent parts of the bit body from becoming balled up. Thev solid matter carried by the fluid discharged from the ports 51 at a relatively low velocitydoes not erode il); abrade the cutting teeth of the cutters I2 and It is believed that the operation of the improved bit provided by this invention will be readily understood from the foregoing detailed description. In operation the bit body I0 is secured to the lower end of a rotary well drilling string andthe tool is operated in a well bore in the usual manner. The bit is rotated and fed downwardly by means of the drilling string and circulation 4fluid is pumped through the string to discharge from the ports 55 and 56. As described above, the cutters II and Ila are spaced below the cutters I2 and I2a to act on the formation at the bottom of the bore W in 'advance of the cutters I2 and I2 and cut or form the grooves A and B, respectively. The cutters II and IIB follow annular courses and cut into the formation to produce the concentric annular grooves A and B. The cutters II and III are short or narrow to rapidly cut into the earth formation and produce the grooves A and B with a minimum of vertical pressure. The central cutter 34 acts on the formation at the bottom of the web I9 to form the substantially central depression or groove C.

The roller cutters `I2 and I2 follow annular paths and act on the formation at the upper faces of the ridges D and E, respectively. The large cutters I2 also engage the formation to cut the bore W to gauge. The cutters I2 are operable to rapidly break down and cut away the ridge D as the ridge is relatively narrow and is unsupported at its inner side due to the presence of the groove A. In a like manner the cutters I2a rapidly cut and break down the ridge E between the grooves A and B. It is understood, of course, that the grooves A and B are former simultaneously with the breaking down of the ridges D and E so that the grooves A and B are always present to leave the easily drilled ridges D and E. 'I'he relatonshlp between the cutters II and II* and the cutters I2 and I2a thus assures the rapid and eiiicient penetration of the earth formation. It will be observed that the cutters of the bit, and more particularly the cutters I2 and I2, operate to shatter or break down the narrow ridges of earth formation as distinguished from the roller cutters of typical well bits that act on broad'extensive faces of the earth formation to cut away the same by a rolling and crushing action.

The circulation fluid discharged from the ports 55 and 56 completely flushes the sets of cutters II and IIa and I2 and I2a and washes about the legs I4 and I5 and the web I9 to maintain the bit free of mud and cuttings. The circulation fluid is discharged in' such a manner that it does not erode or cut away the cutters and 'sufficiently large volumes of the fluid are discharged to properly carry away the cuttings. The cutters and the cutter supporting means are all readily replaceable so that the bit may be easily reconditioned after use.

Having described only a typical preferred form and application of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to thcse skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

l. A Well bit comprising, a body having spaced legs and a web depending between the legs, the legs having openings and the web having a pocket and openings joining the pocket, pins passed through the openings in the legs and extending into the openings in the web, cutters on the pins, a cutter in the pocket projecting from the lower end of the web, and an extension on one of the pins rotatably supporting saidcutter.

2. A well bit comprising, a body having spaced legs and a web depending between the legs, the legs having openings and the web having a. pocket and openings joining the pocket, pins passed through the openings in the legs and extending into the openings in the web, cutters on the pins, a cutter in the pocket projecting from the lower end of the web, .one of the pins having' a socket in its inner end, and an extension on the other pin extending through the pocket to rotatably support the last named cutter and having its outer end supported in said socket.

3. A rotary rock bit including a body to be rotated in the well, two sets of roller cutters, each of said sets comprising a plurality of cutters in axial spaced relation, means supporting the sets of roller cutters at the lower end of the body for rotation about a substantially horizontal axis and with the said sets at opposite sides of the central vertical axis of the body so that the cutters of 'the sets make spaced annular cuts in the bottom of set of cutters in spaced axial relation andin posi-:

tions to act on the ridges of earth formation remaining between said cuts and remaining around the said outermost cut, the lowermost parts of the said second cutters being above the plane of the lowermost parts of the said first cutters.

. LOUIS A. GAUTHEY.

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