US2651501A - Rotary cutter for drills - Google Patents

Description

Sept. 8, 1953 o oN 2,651,501

ROTARY CUTTER FOR DRILLS Filed Feb. 15 1951 INVENT RICHARD D. MC MAHO ATTORNEYS Patented Sept. 8, 1953 UNITED not. a,

PATENTomen 2 claims; (01. 25541):

The present invention relates to rotary boring tools and; more particularly, to shale and rockbits for usein drilling through hard; medium or soft formations.

An important object consists in providing: an 5 improved cone-shaped roller cutter for drilr bits having means for detachably connecting'orlocking each of the cones to the bit spindle on the" outside of the bit so as to prevent thrust or'strai'n beingapplied againstthe body of the bit.

A further objectconsists in provid-ing" mum stan'tiallycone-shaped'cutter with teeth arrangedin axially spaced rows that progressively increase diameter" from the front to therear ends thereof so that the row of largest diameter is positioned adjacent-the'b'ody" of the bitw Addi tionally, the teeth of the" cutter areso shapedand arranged as to" be self-sharpening and'self cleaning during the operation of the bit and may be set or'adjustedat different angles relative to the vertical'axis of the bit.

A" further object consists in providing-5 a shale" and rock bit withmeans for insuring the-drilling of astraight hole a'nd in which the water jets are? located in the'lower portion of the bit body.

A still further object comprherids the provi sion of a substantially cone-shapedcutter for-- drillbits in whichthecutte'r head-*is'preferabhr formed-with a shell and an interfittin'g locking collar to which the shell is detachably'connected.- Additionally, the sectional cutter is= revolublymounted on a'-' downwardly inclined spindle carried by the bit through aball beairing-cohnc tion that functions torevo1ubly'maintain-*the"- cutter'onthe spindle but which permits the "ready and quick removal of the shell section from thecollar section sothat the cutter head may be changed or a new one substituted without'throw ing away or destroying the whole'bit assembly:

Other-objects a'ndadvantages ofthe' invention" will become apparent from the fol1owing'=de'scrip=' tion when-taken in conjunction with the-accom panying claims and drawings:

Referring to the" drawings-wherein is-"showriat preferred embodiment ofthe invention;

Figure 1 isa'side elevationalview of a-rollercutter bit constructed inaccordance with the present invention and'with parts insectionter clearness of illustration".

Figured is a-front endview of Figural Figure 3 is a disassembled view'o'f a'retai-ning spindle and its associated lock'ing" collar; arid Figure i is a detail sectional view or a cutter tooth constructed mascara-ante with the pres'ent invention.

Referringto the drawings in which like nuo morals indicate like parts in the several views, In generally indicates a -rotary shale and rock bit havin alower round or curved hollow head H and an upwardly externally threaded tubular shank- 92' which may be connected to the head through an; intermediate smooth curved or reduced portion l3; Thethreaded'shank l2 may be'tapered"and'is-arranged to be'det'achably connected to a 'rotary drill collar or drillstem so as torotate therewith during the operation of the bit: The'head II is" provided with two or more downwardly inclined fiat smooth surfaces M (Fig. 1 y which vary in number inaccordance 5 with -the-number of cuttersto-be associatedwith the bitr As showni the head II? is formed with two diametrically opposed downwardly inclined fiat surfaces I 4; each of'which has extending outwardly and downwardly therefrom, an inclined 9supportingspindle or axle I5 which may be con n'ectedto the bit in any suitable-manner. Preferably, the head 1 l' is formed with inclined open-- ings -l 6"which extend inwardly and-centrally from thefia-t surfaces It and converge at substantially ,the" axial or-vertical-center of the head I I. The spindles l5 -extend-into the'openings ISso' that their inner ends arebrought intoabutting engagement as-at [1- (Fig: 1')- in order to absorb thethrust of each other; during the; operation of'theacutterzp Ea'Ch"Qf1th8"' spindles I5 is main-' tained in" a fixed position with-in an opening I 6' inanysuitable manner suchasby the spaced spot welds- 5. The innerabutting ends of the-spindle- |5 is eachprovided with a complementary semi- IS arranged-inaXiaIIyspaced rows 26;21 and-22 (Fig. -1)- which may bewariedin number as the particular operating conditions require;- Eachrow=of teeth-'comprisesa b'ase'23 (Fig; 4). It

45 will *be' notedthatthe rows of teeth progressively increase in diameterfronrtheouter row 26 to the-inner row" 22' so as -to impart a cone shape to 'th'e=cutter; and the teeth in each row" arecircumferentiall-v'spaced apart and of substantially ablyisfornied-ofanouter shelli l (Fig; 1 hav inga central longitudinally disposed recess 7 25; the bottom or inner wall of which is curvedas at" 26170 receive a" ball bearing *2? that "also 'fits" 55-1nto a complementary? recess *26 (Fig. i 3') in the adjacent end of thespindle 15. The inner wall of therecess 25 is formed with an annular segmental portion or curved surface 28 which terminates in an outwardly disposed enlarged tapered threaded portion 29 that extends to the inner end of the cone. An annular member or lookring 30 is provided with an externally tapered threaded surface 3| (Fig. 3) arranged to engage the threads 29 of the cone and is formed on its outer or reduced end with an annularsegmental surface 32. The retaining spindle intermediate its length has an externally disposedannular groove 33 which constitutes a race for theball bearings 34, which when the parts are assembled (Fig. 1) also engages thesegmental surfaces 28 and 32 that coact with thegroove 33 in order to rotatably mount the cutter l8 on the spindle l5 and lock the cutter to the spindle so as to pre- 3 through medium formations, smaller teeth but vent its accidental axial removal therefrom. The

ball bearin 21 is preferably of such diameter as to provide a space orpassage 35 between the wall of therecess 25 and thecylindrical portion 36 of the spindle IS. A radial passage 3! extends outwardly from the curved surface 28 and between therows 2! and 22 and may be provided with a Zerk connection so as to introduce a suitable lubricant such as waterproof grease into the bearing surfaces of the rotary cutter. Thelock ring 30 is spaced from the spindle l5 and has its inner wall provided at one end with anannular recess 38 in which is mounted a grease retainingpacking 39, preferably of wedge shape, so that as the pressure is increased thereon by theplug 30, it will form a tighter seal with the adjacent smooth surface of the spindle in order to prevent entrance of drilling mud or escape of grease from the cutter. Thus, means are provided for rotatably mountin the cutter on the spindle and permitting removal of theshell section 24 from thelock ring 30, so that the shell may be replaced when worn out, without disturbing the ring,ball bearings 34 or other parts of the bit assembly. Additionally, thepacking 39 coacts with the seal produced by engagement of the lock collar with the ball bearings and the inner wall of the cutter so as to preclude the possibility of mud and other foreign matter working its way into the bearing surfaces of the cutter. The diameter of each of the ball bearings 28 is such that theannular groove 33 is substantially semi-circular relative to the ball bearings, while the curvature of thesurfaces 28 and 32 are each a quarter of the same circle so as to coact with thegroove 33 to completely enclose the ball bearings when the parts are assembled, and thus prevent the axial removal of the cutter from the spindle. The head I I of the bit between the flat sides 14 and in its bottom may have any number of outwardly extending passages or openings 40 which communicate through the tubular member orshank 12 with the drill in order to supply fluid or water to disintegrate the earth or material during the drilling operation.

The teeth [9 of each row on thecutter 18 are so designed and shaped as to be self-sharpening and self-cleaning durin the operation of the drill, and each tooth extends outwardly and radially from itsbase 23 so as to form converging solid opposed sides 4| and 42 (Fig. 1) which merge into thecurved cutting edge 43 that starts at thebase 23 and extend or taper upwardly in the manner as shown in Figure 4 to theapex 44 of the triangular-shaped end portion 45 that likewise extends upwardly from thebase 23 in more of them are provided. When drillin through hard formations, still smaller teeth and of a larger number or employed. The rows of teeth of different size and number are cut in different diameters so that the cuts in the formation or earth are staggered. When the parts are assembled, it will be seen that the spindles extend downwardly and outwardly from the body H of the bit and the cutters are revolubly locked on the spindles completely on the outside of the bit body. Additionally, thespaced passages 43 discharge a jet of fluid at an angle across the face of the body II and down over each corner so as to clean the same and wash out the cuttings.

In assembling the bit structure, each of the spindles I5 is threaded into its adjacent socket l l. The ball bearing 2'! is positioned in itscurved socket 26 and theball bearings 34 and theshell 24 are positioned so as to fit on the spindle; Thelock collar 30 is then threaded into the shell until thecurved surface 32 thereof is brought into engagement with theball bearings 34. The

shell 24 and the collar 29 are now rotatably mounted on the spindle I5, but are prevented from being axially removed therefrom due to the locking connection effected by engagement of the ball bearings with thesemi-circular groove 33 and the segmentalcurved surfaces 28 and 32. However, theshell 24 may be unthreaded from the collar 29 without disturbing any of the other parts of the cutter assembly. Consequently, when the teeth of a cutter are Worn out, the cutter is not completely discarded or thrown away since it may readily be replaced by a new shell while retaining the same look collar and may be installed at a minimum expenditure of time, labor and cost. The shape of the cutters and the arrangement of the rows of teeth in progressively increasing diameters toward the adjacent flat sides I4 allows the cone-shaped cutter to be placed on the body of the bit so that the cutters l8 will revolve on the spindles and be brought into cutting engagement with the earth formation, such as shale, so as to cut or reduce it to small particles that are forced out of the hole by the streams of water passing down through the spaced passages 40. The teeth of the cutter [8 are formed on theshell 24 so that when it is desired to replace the teeth, the shell is unscrewed from the collar 29 and a new shell is applied or connected to the lock ring so as to be revolubly mounted on the spindle by theball bearings 21 and 34 in the manner as previously described. Proper lubrication of the bearing surfaces is provided through thepassage 31, through which any suitable waterproof grease or lubricant may be introduced. It will be seen that the present invention provides a simple, efficient and economical bit structure in which, when the teeth become worn, they may the form of a pyramid. The spaced straight lines be readily and economically replaced as contrasted to being discarded as was heretofore the custom.

The size and number of rows of teeth on each shell or cutter may be varied. The position of the teeth during the drilling operation is such that the bottom of each tooth engages the formation first and thecutting edge 43 then knifes its way through the formation. As the two outters on opposite sides of the body ll of the drill are inclined inwardly toward each other (Fig. 1) and converge toward the longitudinal center of the bit, it will be seen that during the drilling operation, the earth or material as it is cut or sheared, is crowded or forced toward the center of the hole in the paths of the streams of water discharging through the passages 40, so as to insure an efficient operation of the drill. By reason of the taper of the cutting surfaces of the teeth and the connection of the cutters with the bits, means are provided for preventing the bit from rocking and insures the drilling of a straight hole. Additionally, the teeth as they are worn, are self-sharpened and self-cleaned so that their life and durability are materially prolonged. When the teeth do become worn, they may be readily replaced by withdrawing the shell from its locking ring and substituting a new shell thereof. Thus, a substantial saving is effected since only a portion of the cutter has to be replaced as contrasted to. throwing away the complete cutter as was heretofore customary. It will be manifest that three or four spaced outers I8 may be connected to the head I I by similarly formed spindles l5, and that the size and number of cutters employed will be determined by the particular type of formation with which the bit is to be used. The teeth I9 in each row are so disposed and formed that thecurved cutting edge 43 extends upwardly from in front of the pyramidal end of the adjacent tooth. The upper end of the cutting edge terminates at the apex of its triangular front end, so that the teeth provide cutting surfaces of maximum solidity and strength which extend completely over the area of the cone to insure efficient operation and removal of the shale or formation from the hole.

The form of the invention shown is merely illustrative and it will be understood that such changes may be made as come within the scope of the following claims.

I claim:

1. A rotary drill bit having a head at the lower end thereof, said head being provided with spaced, fiat, downwardly converging sides, each of said flat sides having a downwardly inclined spindle extending outwardly therefrom, each spindle intermediate its ends having an annular groove positioned outside of said head, a substantially cone-shaped cutter revolubly mounted on said spindle, said cutter including a shell section and an interfitting collar section spaced outwardly from said head, said shell section having an internally threaded inner end portion, said collar section having an externally threaded surface engaging said threaded end portion, said sections adjacent said annular groove having segmental opposed surfaces, ball bearings mounted in said annular groove and engaged by said segmental opposed surfaces in order that each cutter is locked to the spindle on the outside of said head, said cutter having a passage therein communicating with said ball bearings for supplying lubricant thereto, and a packing between the collar section of the cutter and the spindle to prevent entering of drilling mud into the ball bearings and the escape of the lubricant therefrom.

2. A rotary drill bit having a head at the lower end thereof, said head being provided with spaced, flat, downwardly converging sides, each of said flat sides having a downwardly inclined spindle extending outwardly therefrom, each spindle intermediate its ends having an annular groove positioned outside of said head, a substantially cone-shaped cutter revolubly mounted on said spindle and spaced outwardly from said head, said cutter including a shell section and an interfitting collar section, said shell section having an internally threaded end portion, said collar section having an externally threaded surface engaging said threaded end portion, said sections adjacent said annular groove having segmental opposed surfaces, ball bearings mounted in said annular roove and engaged by said segmental surfaces so as to prevent axial removal of the cutter from the spindle, said cutter having a passage for conducting lubricant to said ball bearings, a packing between said collar and said spindle, said packing preventing introduction of drilling mud into the ball bearings and the escape of the lubricant therefrom, the parts being arranged so that the cutter is completely locked to the spindle on the outside of said head, and means for supplying liquid into and through the bit to clean the teeth durin the operation of the drill.

RICHARD D. MCMAHON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,374,867 Wadsworth Apr. 12, 1921 1,388,424 George Aug. 23, 1921 1,483,487 Scott Feb. 12, 1924 1,660,309 Duda Feb. 21, 1928 1,789,834 Paulsen Jan. 20, 1931 1,847,824 Failing Mar. 1, 1932 1,918,902 Fletcher et al July 18, 1933 2,061,141 Crum Nov. 17, 1936 2,075,997 Reed Apr. 6, 1937 2,060,117 Dean May 11, 1937 2,187,037 Kirkpatrick Jan. 16, 1940 2,190,350 Catland Feb. 13, 1940 2,427,226 Muhlbach Sept. 9, 1947

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