US2885186A - Drill bit - Google Patents

Description

0. HAMMER DRILL BIT May 5, 1959 3 Sheets-Sheet. 2

Filed Nov. 21, 1956 INVENTOR.

BY zm a May 5, 1959 O. HAMMER DRILL BIT 5 Sheets-Sheet 5 Filed Nov. 21, 1956 0/20 Hammer INVENTOR.

AITO/WVEVJ United States Patent Application November 21, 1956, Serial No. 623,587

2 Claims.v (Cl. 255-314) This invention. relates to bits for boring earth formations and. more particularly to bits in which drilling fluid is. jetted against. the bottom of the hole instead of against the cutters. on the. bit. i

' Roller bits may be: classified according. to the. manner of handling the drilling fluid passing from the drill bit. In what may be termed the normal flow, the outlets from the bits. are located in the central part of the bit dome and direct fluid. directly against the. cutters of the bits to wash cuttings therefrorm In another type of bit, known as the jet bit, well fluid is directed between the. heel teeth of adjacent cutters, and directly onto the bottom of the formationl Thisv action sweeps. the bottom of the hole and .removes the. finelyground cuttings from thebottomv of the hole to permit the cutters to engage virgin. rock and large chunks 'of formation left in the; bottom of the; hole. I,

In the. jet type of bit, it has been. thought. necessary to provid'e ahollow boss. on the. cutter body which. projects radially outward and. also downward from theremainder of. the hod'y,, through which drilling fluid could be' jetted onto the. bottom of the hole. i

Due to. the nature. of. manufacture. and assembly of the components of roller bits,, these bosses. have been the source of considerable. difficulty. Itis customary to forge longitudinal segments. of thefbit head; which are machilled, provided with cutters}, and then welded together. lnforging. tbree'cone bitsection's, the jet bosses necessitate ,smallidiameter pockets and fingers on the dies The fingers sometimes break. off during, the forging process.

'Lhe small diameter pocketsl'and fingers wear more rapidly than the remainder of the dies- The additional. metal necessary to provide the. bosses. increases cost of the bits. The bosses are of necessity located adjacent to or fall within the welding seams of the bitv head- This presents vexatious problems to the welder who must weld a. seam across the dome with the cutters in place and the small area available'to him to work in is partially obstructed by the bosses. Where the weld'seam' swings around a boss in a curve,

the weld is extremely diflicul't. to make. Where the weld seam passes through the boss, it' is difiicult'to obtain a,

seal through the boss which:extendSiromihe-bore through the. hossftothe. exterior of. they boss. Such complete seal is. desirableto. prevent washing. of. well fluid between. the

wall' of the bore and the nozzle insert which isv usually inserted therein.

The. area" about; the body of a. bit. head. and. between thecutten arms: depending therefrom usually provides a passageway forupward flow: of. well fluid; Where this area; is partially obstructed by jet bosses, the return flow area isconsiderably reduced;

withdrawn from the well.

5 in the bits employing jet bosses. 4

2,885,186 Patented May 5, 1959 It has heretofore been thought that the radially outward bosses could not be eliminated without either making the bit head too large in diameter or locating the jet nozzle too close to the center of the bit"and/'o r too far from bottom.

It was discovered that the bosses could be eliminated and the bit head streamlined. Unexpectedly this invention resulted in more efficient washing of the bottom of the hole which made it immaterial that the outlet from the jet nozzles was a little further from the bottom of the hole than with bit heads having downwardlyextending bosses. It was found that my inventionv eliminated the difficult welding job heretoforenecessary, the draft of forging segments was improved, the forging weight was reduced, forging cost was reduced, a less tortuous line of how in thebit head was made possible, and it was possible to eliminate the upstanding deflector in the bottom ofthe bit head bore which was previously employed to direct fluid flow into the bosses.

It is the general object of this invention to provide a drill bit not subject to the foregoing problems. I

Another object isto provide a streamlined bit which will offer less resistance to return flow, to flow around the bit when going in and out of the well, and to present a more pleasing appearance to the eye.

Another object is to provide a jet bit in which. the usual" j'et'bosses are eliminated without making the bit .head too large in diameter or decreasing the. efficiency and easily weldeditogetherl v Another object is to provide a jet bit head made-up of longitudinally split forged segments in which the draft of the forging is improved. i

Another object is to provide a jet bit in which both the weight and cost of the forgings are reduced.

Another object is to provide a jet bit. in which the jet nozzles may be removed from the bottom of the hole a distance further than usually employed without impairing the washing action of the jetted fluid.

Another object is to'provide a jet bit in which the fluid flow path within the bit head is less tortuous than Another object is to provide a jet bit having an open internal bore in which it is not necessary to provide deflectors to direct fluid flow into the jet outlets. 1'

Another object is to provide a bit in. which the bit bodys side wall is circular in cross" section in planes normal to the bit axis except for the downwardly extending cutter legs and in which jet. nozzles are provided in the body which jet drilling fluid directly onto the bottom and side wall of the hole being, drilled. 7

Another object is to provide a jet'bit in which no j'et bosses are present and in which the welding seams for securing several segments of the bit head togetherextend in substantially straight lines to facilitate welding'the segments together.

Another object is to provide a jet bit in which jet outlets are provided without the use of jet bosses to make forging. easier and reduce die wear and breakage.

Another object is to provide bit head segment forgings which may be finished for eithenconventibnal or jet fiow' without the provision of jet bosses.

Another object is to provide a jet bit in which the fluid from the jet nozzle .is directed in part'on'to the track of the heel teeth of the cutters and in partonto the side wall of the hole to increase the velocity of'the jet stream flowing along the bottom of the hole toward the central axis thereof.

t Other ohjectu features and advantagesot this invention will be apparent from the drawing, the specification and the claims.

In the drawing wherein like reference numerals inlikeparts and wherein there is shown illustrative of this invention:

Fig. l is a view invertical cross section througha hit in accordancewith this invention and taken Fig; 12in horizontal emit section of the hitof Fig.1

11m 2-: atrial is elevational view of the bit of Fig. 1; UFig. 3lls an internal elevationalview of a forging segtllelbittbody of a modification otthe drillbit 1 wherein the bore is positioned for conotwthe gment being otherwise unchanged.

Fig.4 isanexternal elevational view of'the forging onto the bit cutter teeth, the conwelded together. In the bit ti segments are employed, each over third of the bit head indi- W v at ll. The upper end of the bitfhead 1 a threaded pin 12 to permittheblt to to a drill pipe. ts, above the dome, indicated generally at in crosssection in a planelnormal to when the sections are assembled into I there is formed a hollow bore indicated generally at 15 which terminates: above dome 9 which we on: its lower :end.:a downwardly and inwardly generally atzli whichis the legs} are joined together to permit 11 tobe mounted onthe legafbefore :the

provided hythe conventionalroller hearare in place on the spindle. Theballs are inagaedthrough a bore from the exterior of the ilgltt l'lheboreisclosedbyaplug 16a whiehiswelded method of assembly is extensively The legs 14 extend radially outward y it as downwardly. The cutter lega Thus; room is left adjacent legs ior both downward time: the the sidewall of thehole wlltlfloioffluidvafterithls ietted" hole. 'lhei;same space is utilized lapse-v wall of the'holejwhile the lowered in in the hole. legs adjacent one longitudinal forging segment, thenozzle bores 22 for the jet honlea mayeach be entirely contained within a'forgviewshowingafurthermodi it of p rality or tumm idea-v the exterior of the bodyattthe upperendt'ot the together.: The mounting for the t a 55 qn tha lowerendofeachsegtnent ham aegis Y awa adjacentone longimdinal edge 21 so,

ing of these seams. roomprovided between the cutters and dome to permit easy'accesstotheweldgroovesflaandlh tor-welding.

to the center line its jet nozzle bosslwere provided which projected cuttersl'landagainstthebottomandsidewallotthe hole.

FI'OmFiKS; 1and2itwillbeseenthatinanyplane ofthebitheadnormaltothebitaxis,thesidewallof the bit heathexcept for the projecting cutter legs, is circularinoonflguration and inparticular the side wall portionliiintermediatetheradialextensionofcutterlegs 14iscircular andtreetrom protrusions. Thus,thereis no radially which would interfere with upward flow of drilling fluid past body 11. Furthermore, the of the conventional jetboss at thispoint increasesthedraftiofthe forgingandnodiificultyisexperiencedinremovingthetorgingfiomthe (:3. Notethedaaheddiepartinglinesuonl igs. 3

v 4. w it The pic shaped dome sectionsnare provided: with straight lines radially outward from the centerolthe body. It is particularly pointed 'out that there is no downwardly extending jetjboss which would intersect the weldseams in the dome, cause the weld seams to circle about the boss. or in any way interfere with the weld- One particular advantage is the Fig. 1 that the jet radially from thebody 'andhence the curve 29 in bore '15 is much gentler than in thecase of the bit 45 the bore 15 to the jet head. Theieforeless energy is requ pumps to florce drilling fluid out the seen in Fig, 2.the divergenceof nozzles 31ia along a line which substantially bisects the space between adjacent cutletsl'l.

It will be seen that a portionof thetiuida noflleinbores n willstrikethetrackoftheheelteeth otcuttersflandaportionwillstrike thesidewalland thentravel downwardly to thebottomot the hole. This portionobthe'jetted fluid striking the side wallof the hole will tend to turn radially inwardly toward the center of the hole and provide a high velocity stream moving toward the center of the-hole. This should becontrasted with the conventional jet bit in which the jet stream strikes the bottom of the hole in its entirety andis free ing section and direct drilling fluid between adjacent F15 to spread about 360 degrees. Obviously, the portion of the fluid the side, wall. vt l if' enst .tlov toward the center of the hole, and when, dried to. the fluid which strikes the bottom 'of' the holeandtendjs to flow toward "the center of the hole will provide a: large volumehigh velocity stream which will remove small cuttings from the bottom of the-holeahd perinit the cutters to engage either large chunks. of formation have been. broken off or virgin rock.

High velocity drilling fluid is very abrasive and for this reason it is preferred that the fluid be jetted through nozzles of very hard material such as tungsten carbide. Therefore, instead of providing jet nozzles as part of the body, it is preferred that bores 22 be provided and special hardened nozzles such as nozzle 31 be positioned in these bores. Any desired form of nozzle and means for securing a nozzle in place may be used. In the form illustrated in Fig. l, the !bore 22 is counterbored at 32 and the nozzle 31 is provided with an outwardly extending flange 33. A suitable seal such as O-ring 34 is positioned in the counterbore under the flange and after the nozzle has been inserted from the interior of the bit head, a snap ring 35 is positioned in a groove in the protruding end of the nozzle to hold it in place.

Referring to Fig. 6, a different form of nozzle is shown in which bore 22 is counterbored at 36 from the exterior of the body and a groove 37 having an O-ring 38 therein is formed in the counterbore. Nozzle 39 is inserted from the exterior of the body and a snap ring 41 is positioned in a groove 42 below the nozzle 39.

In Fig. 7, there is shown a still further form of nozzle in which an O-ring 43 seals between the nozzle bore 22 and nozzle 44. Mating grooves are provided in the bore 22 and exterior of nozzle 44 to receive a key 45 which is inserted through a hole 46 in the side wall of the bit body. The key 45 is resilient and crinkled as shown in Fig. 8. The key is locked in place by the frictional engagement between the keeper and groove, but may be removed by pulling the loop on its outer end. This form is distinguished from those in Figs. 1 and 6 in that no counterbore is required, the key holding the nozzle against displacement in both directions. It will be understood that this key may take other forms than the crinkled member shown, so long as it is flexible enough to be forced in and removed from the mating grooves when desired.

Referring to Fig. 9, there is shown a still further form of nozzle which is identical with that shown in Fig. 1 except that the nozzle 31a is somewhat longer to position its outlet closer to the bottom of the hole. In some cases this is desirable to obtain maximum jetting action. As the nozzle is of very hard brittle material, it is subject to damage from protrusions on the side wall of the hole, etc., and a shroud 48 may be welded to or otherwise formed on the bottom of the body at 49 to protect the nozzle against damage. Preferably, the shroud 48 extends circumferentially at least a slight distance on either'side of nozzle 31a to provide protection and may be joined to one or both adjacent cutter legs to give it added strength.

In the fabrication of bits in accordance with this invention, the segments shown in Figs. 3, 4 and are forged in the usual manner. Then the jet nozzle bores are drilled and the bearing surfaces machined to provide the bearing races 16. Roller bearings are then placed about'the bearing surfaces on each spindle and cutters 17 are installed on each cutter leg. The balls 19 are then introduced one at a time in the bore in the side wall of the arm. The bore is then closed by plug 16a. The three segments are then placed in a jig and the weld grooves in the side wall of the body and in the outside wall of the dome are filled with weld material. Thereafter the threads 12 may be cut on the pin at the upper end of the body and the jet nozzles installed. Where the long jet nozzle 31a is used with a separate, weldeddeme'a e s bstantia ly flatan ne rly pa allel to each otli This nermits; r adadri ingiot holes attire; center por of the beds nboard fironr he jet; 1: lee.- illustrat i,

for instance as shown in dashed outline atr, 4,75 in Big. 3,. Thus, one or more holes 47 may be drilled in the dome in lieu of the jet nozzle bores 22 and what may be referred to as normal flow conducted through the center portion of the bit body and directly onto the cutters 17. It will thus be seen that the single forged segment may be used in both the jet bit and the conventional flow type bit. The elimination of the jet bosses both reduces the amount of metal in a forging and increases die life. When these factors are weighed with reduced raw material inventories and reduced maufacturing costs, it will be seen that the use of a single segment for both types of bit will compare favorably with specially designed segments for each type of bit.

From the above it will be seen that all the objects of this invention have been attained. There has been provided a jet type roller bit in which no jet bosses are necessary. The welding of the three segments together is much simpler than in the boss form of jet bit as the welds are in substantially straight lines. There are no bosses to obstruct access to the dome welds and these welds are readily made. The jetted fluid is in part thrown against the side wall of the hole to improve the flow characteristics of the fluid on the bottom of the hole. In other words, the fluid velocity washing across the hole from the side to the center of the hole is increased.

Problems of sticking of the forging segments in the dies are overcome with this invention. Also, the segments may be used for conventional fluid flow bits as well as the so-called jet bits.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood and acknowledged that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

1. A drill bit comprising, a plurality of substantially identical elongate segments arcuate in cross section secured together to form a hollow head, each of said segments having a downwardly extending cutter leg adjacent one longitudinal edge of the segment and an inwardly projecting wedge-shaped section, cutters on said legs below said wedge-shaped sections, said bit head having a circular side wall and a transverse dome over'said cutters formed by the assembly of said wedge-shaped sections and said dome having substantially flat and parallel upper and lower walls, said side wall and dome being free from protrusions except for the legs which project beyond the dome and radially beyond the side wall of the head, said segments being secured together by welding the dome sections together along the outside edges thereof and by welding along the longitudinal edges of the segments, and a downwardly extending jet nozzle bore in each segment adjacent the other longitudinal edge thereof and connecting with the hollow interior of the bit head and having its lower terminus at said lower dome wall, a nozzle removably secured in said bore and arranged to direct flow from the head downwardly between adjacent cutters and in part toward the track of the heel teeth of the cut-

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