US2032328A - Drill bit - Google Patents

Description

Feb. 25, 1936. M, E REEDY A 2,032,328

DRILL BIT Filed Deo. 19, 1935 2 sheets-sheet 1 T Il" f :IE- l Il,

3k Ira- E ,9 y,

| /j r/ {'I l J I I 5 f, INVENTOR.

y i @VCM/wlw 6. @lez/15% 2? BY FM JDM, 2,5 43 47 4.5' ATTORNEYS.

v Feb. 25, 1936.

y M. E. REEDY DRILL BI'1 Filed Dec. 19, 1953 2 Sheefs-Sheet 2 'i Ir-:TQLE l INVENTOR l am ATTORNEYS.

Patented Feb. 25, 1936 UNITED STATES PATENT oFFlcE I 2,032,228 mum. Brr

Melvin E. needy, ATulsa, om, signor a Franklin G. Reedy, Warren, Ind.

Application December 19, 1933, semi No. 703,110

' 13 claims. (cl. 255-63) cable drilling, and it is particularly with refer-` ence to the latter method that the present invention is directed. In this method' of drilling, a relatively heavy drill bit is suspended at the end ofa longcable which is raised and lowered by means of a walking beam, jerk line, or other means of imparting the reciprocating drilling motion to the cable 1.; and tools. The drill bit, always the lowermost member of the assembly ofthe various drilling tools, is usually of very substantialweight and includes a cutting surface at the lower end, a body of five to eight feet or more in length, and

a wrench square above which is a threaded tapered pin which is attached to the threaded tapered box at the lower end of the drilling stem. 'Ihe upper or opposite end of the drilling stem has a threaded tapered pin to which is attached the threaded tapered boxof the rope socket attached to the lower end of the drilling cable, or a set of Jars may be interposed. When such drilling tools, whose suspended assemblies weigh several thousand pounds in the larger sizes of hole, strike thc bottom of the hole, they. exert a tremendous force and particularly when in contact with the harder viormations are subjected to great shocks, and excessive vibration. f

In the drill bits proposed by' the prior art, it

has been' customary to employ bits which are provided. 'withfrelatively 'flat chisel-like cutting surfaces, and therefore likely to have their vertical direction altered'in contacting certain diflicult formations .in the earth. To prevent this deflection, various proposals have been made' for changing the character of the bit cutting surface,

orfor adding reaming members to thefbit body,

55 removal is diillcult, if not practically impossible.

It is therefore among the objects of the present invention to provide a drill bit preferably made as a single unitary structure which isv attached to the drill stem by the usual threaded tapered pin and box joint, and provided with 'a pilot point. 5 that dlrects'the drill bit at the bottom of the hole and makes a straight hole.

It is also an object to provide a drill bit which has a tapered end so that the cutting end of the bit does not contact a flat bottom in the hole, but 10 produces a hole with a concave bottom, with weakened edges which are readily broken away and mixed with the drilling fluid.

It is a further object to provide a novel method. of preparing drill bits embodyingytherpresent in- 1 5 vention and also a method by means of which the conventional drill bit's now in service may be adapted to the form proposed in the present invention in a simple and expedient manner.

It is a further object to prepare a drill bit, Prov20 vided with a pilot point and a tapered end upon which stepk cutters are formed, which makes a concave bottom with weakened sides, thereby greatly reducing the shock and vibration on the pins and boxes and other sections of the drill- 25 ing assembly and minimizing breakage of samc.

It isa still further object to prepare a drill bit provided with a pilot point and a tapered end upon which step cutters may readily be formed and surfaced with a hard, wear resisting alloy, 30 giving long rlife to the bit `and making for more rapid drilling progress.

Further objects include the provision of auxiliary peripheral reaming cutters which maintain the gauge vthroughout long service and prevent 35 tapering of the hole being drilled.

These and other objects which will be apparentl from the sequent description are all embraced within the present invention, illustrated in the 40 accompanying drawings, in which;

Figure 1 is a front'elevation Aof a drill bit embodying one modification oi' the present invention;

Figures 2 andl 3 are side and bottom views, 45 respectively, of the same embodiment, showing only the cutting end;

Figures 4, 5, and -6 are front, side and bottom views, respectively, of the cutting end oi' a second modification; v

Figures 7 and 8 illustrate the' steps in preparl ing a drill bit embodying the present invention from a conventional form;

, Figures 9, 10, 11, and 12 illustrate the steps in'prparing a drill bit embodying the present invention from a modified conventional form; and

Figures 13 and 14 are cross sections taken along the lines I3-I3 and I4-I4, respectively, of Fig. 3 to illustrate the method of building up the stepcutters, anges and cutting edges as wel as surfacing them.

'I'he drill bit of the present invention, which is designed primarily for percussion drilling, may, of course, be embodied in other'forms for similar or analogous drilling operations. It involves the usu'al bit body which is of substantial length, from five to eight feet or more. and generally cylindrical in shape, the diameter of the cylinder being slightly less than the gauge of the hole to be drilled. To provide passages for lthe drilling fluid, portions of the cylindrical body l may be cut away as by the intersection of chords on the circular perimeter or, in addition, by U- shaped grooves on the-flattened surfaces. Al-

ternatively, V-shaped grooves may be made into face so that the bottom of the hole is not flat but concave or, more accurately, in the'general shape of an inverted cone. This portion of the drill bit mayassume other generally conical surfaces such as shapes Awhich provide a surface that decreases in size toward the end. At the apex of the conically tapered surface is a gcnerally cylindrical extension which projectsl from the apex. This cylindrical extension forms a hole of substantially less size than that of the main portion of the hole and acts as a pilot point in directing the drill bit. At the periphery of the conical surface, that is', its junction with the cylindrical surface of the drill body, a flare is built up which has a diameter or gauge substantially that of the finished hole. On this are are auxiliary reaming cutters and in addition one of the step cutters, more particularly hereinafter described, may be included. These auxiliary reaming cuttersand the edge step cutters maintain the proper gauge for the hole. .On

the conically tapered surface are built up what may be termed step cutters which may be arranged in any suitable fashion, that is. either in direct line, helically or other more or less uniform arrangement. These step cutters are triangular in cross section, having the hypotenuse on the conically tapered surface and a right angle opposite thehypotenuse and provide a cutting surface in the general shape of an annular sector, although the non-circular edges may be those of chords rather than radii. The side edges of the steps form substantially right angles with the cutting surfaces and provide a sharp edge to assist in the cutting' operation. The step cu'tters need not be, and preferably are not, on alllv radii of the conical surface to permit the ready passage of drilling uid and since in operation the drilling tools suspended on a long twisted cable tend to rotate and different sectors of the conically tapered surface is also flattened on one or vtwo sides as by chords of the circle and the bottom surface is provided with a hard, abrasionresisting metal. The -cylindrical portion of the 'acsasas extension is flared out by building up the metal so that the cutting surface is slightly larger on the arcuate edges than the cylindrical extension itself.

Considering now the invention as illustrated in the drawings which, however, are not to be taken as limiting, butsimply as illustrating some of the many possible modifications of the present invention, attention is directedto Figures 1, 2, and 3, in which I is the body of a conventional drill bit that is flattened on two sides as by chords l so that the body does not completely ll the hole. 'I'he upper end of the bit body is tapered 01T at 5, on which section is a wrench square 1. Above this is the threaded tapered pin 9 which is attached to the. threaded tapered box of the stem by wrenches used on either a. circular or straight jacking track. Extending along the cylindrical portion of the body of the bit on the flattened sides are U-shaped grooves I I to provide channels through which the drilling fluid may readily now. At the upper extremity of the channel it may diminish somewhat to a smaller channel II.

At the base of the cylindrical portion of the body I is a flare I1 of slightly greater diameter than that of the cylindrical body by about .05 to .10 which is substantially the gaugey of the hole. 'I'he method and materials used in forming this flare will be considered morespecincaily in connection with Figs. 13 and 14. Below this nare the drill body tapers rapidly in the f orm of a conically tapered surface I9. On this conically tapered surface are the step cutters 2| which, as illustrated in Figs. 1, 2, and 3, are diametrically opposed. Extending from the apex of the conlcally tapered surface is the generally cylindrical extension 23 which serves as a pilot point. This extension has flattened sides 25. On the arcuate portions of the generally cylindrical extension a flare 21 is provided and the bottom surface'is given a at, chisel-like face 2l built up of wear-resisting alloy. The last step cutter from the apex of the conical surface, designated as 3|, is partlybuilt up directly on the are I1. Adjacent the step cutter 3| are. auxiliary reaming cutters 33 which assist in maintaining the proper gauge of the hole.

As stated above, the drill bit of the present invention may either be originally constructed according to the teachings of the present invention or the conventional types of drill bits may be modified to embody the novel features herein described.

If the operator is of a drill bit gen-- .erally similar to that shown in Fig. 1, except that the end has the conventional fiat chisel-like cutting surface 1 I, as shown in Fig. 7, which type of drill bit is normally dressed by forging, he may secure the advantages of the invention by removing the tempering and -machining' or otherwise working the end ofthe drill bit to secure the structure of Fig. 8 which includes-the bit body I with an annular cut-out portion lI, conically tapering surface I and a generally cylindrical extension 2l from the apex of the conical surface.

Whether the structure illustrated in Fig. 8 is secured from machining a conventional drill bit or prepared in original manufacture, the step cutters, auxiliary reaming cutters and pilot point may .ie-built up and arranged thereon in-the manner shown in Figs. 13 and 14 by electric arc or Oxy-acetylene welding.Before vbuilding up these members on the parent metal by oxyacetylene welding -the end of the bit should be llame is not so rapidly dissipated as it is in cold metal. A tough, abrasion-resisting alloy (such as Stoody Self-Hardening," Hascrome, or other similar alloy) is welded onto the end and cylindrical side near the end of the cylindrical extension 23 as 'at 35 and on the conically tapered surface |9 to build up the step cutters 2|. This alloy is also employed to flare the cylindricall portion of the -bit body and form the last step cutter 3| which is lower than the annular groove 8|.' On the surface of the alloy used to build up these members is.welded a still harder, wear and abrasion-resisting alloy (Stoodite, "Stellite, or other alloys having similar properties), at 3l. This relatively thin coating is applied on the cutting surface and the edges as well as extended a short distance along the side.

Fig. 14 illustrates the structure of the auxiliary reaming cutters which are arranged on the annular groove 8| and the built up flare |1. These auxiliary reaming cutters are built up in the same manner as the step cutters or the pilot point and, in addition, since being on the periphery, they are subject to particularly hard wear, they are given an overlay of very hard alloy (such as Borium,.Haystellite Composition, or similaralloys). While'speciilc alloys have been mentioned in connection with building up the cutting elements of the bit on the parent metal, it is to be understood that these are given as illustra- .tive of those which have been found successful,

i but that other alloys possessing generally simi- ,l lar properties might be employed in their place.

When the cutting members, cutting edges and surfaces have been built up as described, the bit, preferably is again placed in the furnace and brought to a Inormalizing heat, after which it is allowed to cool in the atmosphere. The step and reaming cutters on the outer circumference, i. e., 3| and 35 of the cutter head, should be kept as large or full to the gauge of the casing in the well as possible, otherwise no great care need be taken in finishing the step cutters to any particular gauge, as in actual use a percussion method bit drills a hole having a diameter of 1.05 to 1.10 or more of the greatest diameter of the bit.l

It is probable that the drill bit of the present invention may be prepared by those skilled in the art by methods other than the novel ways described, but it should be understood that this invention includes the novel drill bits by whatever method they may be prepared.

After the drill bit has been in use for some time it will, of course, wear down and thel edges of the step cutters may be rounded off to some extent and also the auxiliary reaming cutters as well as the last step cutters may be worn down so as to decrease the diameter of the hole drilled, 4

ing up layer of alloy .and an additional layer of a harder, abrasion and wear-resisting alloy.

Figs. 4, 5, and 6 illustrate an additional modification in. which the step cutters instead of being on a single diameter as in Figs. 1, 2-, and 3,v

are staggered or arranged helically with opposite helix on opposite sides so that each` step cutter in a given position has a corresponding step cutter diametrically opposed as, for example, lul-4|, 43-43, 45-45, 41-41. In this modication auxiliary reaming cutters 33 are also provided on the circumference. The pilot point 23 is illustrated as having the axis of its flat, chisellike face somewhat oblique to the chords cutting the cylindrical surface of the bit body In Figs. 9 to 12 are illustrated the development of abit embodying the features of the present invention from the conventional cross or star 'shaped bit, which development is similar to that shown in Figs. 'l and 8. When, however, the step cutters of the present invention are employed in connection with a star or cross shaped bit, they are put on two axes at right angles to each other. Otherwise the arrangement is generally similar to that of the embodiments formerly considered, with the exception that on one axis there would normally be two more cutters, as 9|, since these cutters are omitted from the conically tapered surface l93 in order that there will be no continuous member above the cylindrical extension 23 which would tend to obstruct the drilling fluid and prevent its free passage along the sides of the bit or through the channels otherwise provided.

While the invention has been described in great detail with respect to the several modifications thereof, these are not to be construed as -Y ery of -the drill.

2. A .unitary percussion drill for earth boring having a body member terminating at its lower end in a downwardlytapering conical surface from which projects a centrally arranged cutting 'and pilot point of a. vdiameter substantially smaller than the diameter of the drill body, and a plurality of arcuate cutters on a portion of said conical surface just above the pilot point extending in stepped relationship toward the periphery of the drill, the several stepped cutters being formed in relatively small segments; with intervening spaces, such spaces providing for the 'ready 110W 0f the drilling fluid.

3. A unitary drill bit for percussion earth boring comprising a drill body, a conically tapered end surface, arcuate cutting edges on a rtion of the conically tapered surface, a pilot int projecting from the apex of the conical surface and a channel. extending along the drill body cutting away a portion of the conical surface. 4. A unitary drill bit for percussion earth bor- -ing comprising a drill body, a conically tapered end surface, permanent arcuate projections from a portion of said conical surface provided with cutting edges and surfaces and 'a pilot point pro- `face, arcuate projections triangular in radial cross section permanently attached to and projecting from a portion of the conical surface in stepped relation to act as cutters.

6. A drill bit for percussion earth boring comprising a drill body, a conically tapered end .surface, arcuate projections triangular in radial cross section permanently attached to and projecting from a portion of the conical surface in helical stepped relation to act as cutters 7. A drill bit for percussion earth boring comprising a drill body, a conically tapered end surface, stepped arcuate projections triangular in radial cr'oss section permanently attached to and projecting from a portion of the conical surface to act as cutters and a pilot point extending from the Vapex of the conical surface to center and direct the drill.

8. A drill bit'for percussion earth boring comprising a drill body, a conically tapered end surface, stepped arcuate projections triangular in radial cross section permanently attacher to and projecting from a portion of the conical surface to act as cutters, a pilot point extending from the apex of the conical surface to center and direct the drill and a channel extending along the drill body cutting away a portion of the conical surface.

9. A unitary drill bit for percussion earth boring comprising a drill body, a conically tapered end surface, projections from a portion of said conical surface providing arcuate cutting surfaces and auxiliary reaming cutters on the periphery of the conical surface which extend slightly beyond the generally cylindrical surfaceV face which extend slightly beyond the said cylindrical surface ofthe drill body, a pilot point extending from the apex of the corneal surface to center and direct the drill and a channel to permit the passage of drilling uid extending `along the drill body cutting away a portion of the conical surface.

l1. A drill bit for percussion earth boring comprising a drill bit body having a peripheral are to form auxiliary reaming andl crushing surfaces, a conically tapered end surface, annular sectors forming cutting members including projections substantially right triangles in radial cross section disposed Ain regular stepped relation on portions of the conically tapered surface, each projectionA having its hypotenuse on the conically tapered end surface to provide cutting and crushing surfaces disposed at right angles to the axis of the bit, and a pilot bit with cutting edges and crushing surfaces extending' from the apex of the conically tapered surface.

l2. A drill bit for percussion earth boring comprising a drill bit body having a peripheral flare to form auxiliary reaming and crushing surfaces, a conically tapered end surface, annular sectors forming cutting members including projections substantially right triangles in radial cross section disposed in helical stepped relation on portions of the conically tapered surface, each projection having its hypotenuse on the conically `tapered end surface to provide cutting and crush-l ing surfaces disposed at right angles to the axis of the bit, and a pilot bit with cutting edges and crushing surfaces extending from the apex of the conically tapered surface.

13. A unitary percussion drill for earth boring having a body member terminating at its lower endin a downwardly tapering conical surface from which projects a centrally arranged cutting and pilot point of a' diameter substantially smaller than the diameter of the drill body, and a plurality of arcuate cutters on a portion of said conical surface just above the pilot point extending in stepped relationship toward the periphery of the drill with adjacent conical surface, whereby said arcuate cutters act tochlp oil.' earth formations at the conical bottom of the hole and the conical surface adjacent the cutters assistsl lin mixing the loosened formations with the drill-l ing uid.

' MELYIN E. REEDY.

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