US2696973A

US2696973A - Nonsticking drill bit

Info

Publication number: US2696973A
Application number: US210264A
Authority: US
Inventors: Eric A Baumgartner
Original assignee: FRANCIS R BRITTON; JOHN OSCAR BERGMAN
Current assignee: FRANCIS R BRITTON; JOHN OSCAR BERGMAN
Priority date: 1951-02-09
Filing date: 1951-02-09
Publication date: 1954-12-14
Anticipated expiration: 1971-12-14

Description

.Dec. 14, 1954 E, A, BAUMGARTNEQ 2,696,973

NONSTICKING DRILL BIT Filed Feb. 9, 1951 Q 2 Sheets-Sheet 2 3nbentor ERIC A. BAUMGARTNER (Ittomeg United States Patent ice 23%,9173. NoNsrrcKme "D'RILL BIT Eric A..Baurn gartner, near Boulder, Colo:, assignor of one-eighth to Francis'R..Britton and one-eighth tofJohni O'ScarBergm-an, both ofDeriver; Colo;

Application February 9,1951, serial No; 210,284 '9 Claims. (C1. "255 64) minimize, ifnot wholly eliminate, sticking. or, hangingv of the drill in the bore. p I

A further object of the invention is to provide improved means for guiding andsupporting a percussive drill bit in non-vertical drillingopefra'ti n's.

A furt er .object ofthe inveiition is'itio proyideiiriproved means; operable as an: iiiql ent of 1c nventionalf-percussive drill actuation to scavenge and clear the 'res'ultingbore.

A further object. of the invention is to provide an improved, percussion-type drill bit. of enhanced penetrative efficiency and'extendedope'rative life.

A further object of the invention is to. provide an improved, 'percussion-type.drill bit operable withcutting. effect in reaction to both rotational and. axiallyapplied' phases of conventional drive. v I a A further object of theinvention is to provide, an improved, percussion-type drill bit that is simple and inexpensive of production in an. extensive variety of partic'ular sizes and forms, that is rugged, durable, and efiicient in use, and susceptible of ready rehabilitation in the field.

With the foregoing and other. objects in view niy' invention consists in the construction, arrangement, and combination of elements hereinafter set forth, pointed out in my claims, and illustrated by the accompanying drawing, in whichv p v Figure 1 is a side elevation of. a typical-drill unit coin prised from a conventional bitand a stern modified in accordance with certain principles of the invention, an intermediate portion of the stem being broken away to conserve space. Figure 2 is across section, on an enlarged scale, taken on the indicated line. 2 2 of Figure 1..

Figure 3 is an elevation of the cutting. face or working.

end of a typical; percussion-type. drill bit. incorporating certain features and principles of the invention. Figure 4 is a sideelevation of the construction according to Figure 3. Figure 5 is a fragmentary,detail section, on an enlarged scale, takensubstantially on, the indicated line 55 of Figure 4. H a section, on an enlarged scale, taken substantially on- .the indicated line 66-ofjFigure 4. Fi ure 7 is a view similar to Figure 3 of a relatively modified bit cutting face within the contemplation of the invention. Figure 8 is a. side elevation of the construction according to Figure 7.. Figure 9 is a view similar to Figure 3 showing a somewhat modified arrangement of the elements thereof. Figure '10 is a side elevation 'of the construction according to Fiszure9. w i v Percussive drilling of nonvertical bores in earth strata by hitherto 'conventional means and agencies is cornmonly characterized by a gravitydnduced deviation of h a w r t i ht l xi a sa e l cavs ing of. cuttings trom the. bore with consequent reduction of drilling efficie'ncy, and by a grievous tendency "of the hit to catch h a k la ive to th" bore walls d t ngth g a;

was 99 ton es entia to hit replacement, ad ustment of stem '-leng'th-,-and the Figure 6 is a fragmentary, detail 215536373 Patented Dec. 14, 1%54 2 like, and it is hence "to the elimination of suchdisadvantageous characteristics that the improvements of the instant invention are directed.

Representativejof conventional practices, and as shown in Figures 1 and.2, a drill 'stem15 in the form of a straight length of suitable metal, suchas round. or hexagonal bar stock, is. formed.withanaxial bore 16 for the translation of cooling and scavenging jfluid with an angularly: surface'dend 17 receivable in the chuck of a jack-hammer whereby the stern i's-both axially driven androtated, with afixedly-related collar 18 limitingthe length. and determinin thechuck-engageable extension of the end.1'7, and withnits otherfend. worked to the form of a coaxial, shouldered stud 19, usually threaded, for engagement withv andto operatively mount a socketed drill bit 20 of conventional type; all ofwhich is common and Well known in;the related artland practice.

Conditioning the conventional assembly illustrated and above describedfor improved scavenging effect incidental to the usual rotational and percussive power drive thereof, a feature of this invention is the provision of a spiral. fin exteriorly about and alongthe stem 15, or at least that portion, of said stem adjacent thebit 20, pitched to apply stem rotation to retraction.ofJcuttings-from the bit working face or inner [bore end toward the open or entering end of s'aidbore. While spiral. fins exteriorly of drill stems for auger-like extraction of cuttings are not new, per se, the generally-available percussive drill.:stem sections. are not commonly so equipped and the production of drill stem sections with integral spiral fins is reflected in an onerously high unit cost, hence th'e novelty and advantage of this "feature of. the invention reside in a fin construction andoperative mounting-thereofwhich are inexpensive and susceptible of. convenient utilization; As shown in Figures 1 and 2, the spiral fin featuringthis invention is developed from a' length of suitablewidth-strip metal 2'1 by winding said-strip, as upon'and'a-bout a'rnandrel, to the form of a suitably-pitched, hollow, spiral coil having an internal diameter slightly exceeding the maximum diametric dimension of the drill stern'section lfiwhereupon the coil is to be mountedand an exterior diameter slightly less than the diameter of the bore susceptible of development by the as'sociatedbit 2.0. The'coil constituted from the strip 21 having been formed, a slot or groove 22, pitched in conformity with the convolutions of said coil, is cut or ground circumferentially of the stem collar 18 in a depth and width accornmodative of the coil strip and said coil is thenrotated through said slot or groove and axially of the stern 15 until the said coil has passed beyond the-collar and into loosely embracing, slidable relation with the stem, where'after the coil is moved into end proximity with the Stud 19 and is there positioned and fixed bvmeans' of welds or brazings 2-3 disposed to unite spaced points of the coil inner circumference with adiacent stem areas. As is manifest, the spiral fin coils are susceptible of convenient production in sizes appropriate for useon' and with conventional drill stems, to which theymav' be applied byaanv user having access to usually-available equipment, and the presence of a spiral fin coil on the drill stem portion adiacent the bit applies. rotation of the drill assembly to effect mechanical extraction of cu tin s in a manner efiiciently supplementing cltc omarv Hui l shave-point;- I

Conventional percussion drill bits of the type within thecontemplation of this invention, and as shown at 20 in Figu re 1, are characterized, by a plurality of'angularlyspacedteeth 24 separated. by flutes or channels 25 longitudinally of and interrupting the drill body exterior surface for accommodation of scavenging-fiuid-flow and cuttings trav el. Theteeth 24 are 'alike in an angular convergence axially of th e body definitive of a tooth cutting edge s ubstantially radial of the bit-working face and ex-. tending from the fluid flow bore 26 axially'intersecting the bit body to anouter end. or corner outwardly overhanging the bit bodyand, with its counterparts, determinative of the borediameter. In the use of bits of the type.

3 said teeth are prone to catch and hang on the rough bore walls when the assembly is withdrawn from the bore for servicing or replacement of the bit, and it is to the practical correction of such deficiencies that the further features of the invention are directed.

In accordance with the principles of the invention, the cutting efiiciency and the useful working life of the bit teeth 24 edges may be materially enhanced by armoring said teeth edges with blocks 27 of appropriate alloy material, such as tungsten-carbide, having the form of rectangular wafers. Blocks of Wear-resistant alloy material appropriate for arming of the teeth 24 are commercially available in a variety of shapes, sizes, and proportions, hence it is practical and wholly feasible to obtain wafers suitable for the desired use in mounted relation with the wedge-shaped teeth 24 of variously-sized bits 20. The blocks 27 selected for mounting on a given bit should have a length, or maximum dimension, at least equal to the length of the tooth 24 cutting edge with which it is to be associated, a width on the order of half, or less, of its length, and a thickness on the order of half, or less, of its width, and one such block 27 is placed flat against the slope of each tooth 24 trailing in the direction of bit rotation with the axially-outtermost long edge of the block registered in alignment and in the same axial plane of the bit body with the associated tooth cutting edge, in which position and relation the said block is fixed and secured by a welded fillet 28 filling the angle between the block 27 trailing edge and the adjacent tooth surface, adhered to said block edge and surface, and overlapping a trailing portion of the exposed block width, as is clearly shown in Figure 6; it being within the contemplation of the invention that the contacting block and tooth surfaces may be correspondingly united by welding or brazing through the application of known techniques. Mounted as shown and described, the inner long edge corner of the block 27 projects beyond the axial plane of the associated tooth cuttin edge, as indicated by broken lines in Figure 6, and conditioning of the so-mounted block for actual use involves a grinding away of such projecting corner, and a portion of the tooth 24 surface underlying the same, to provide a chisel-edge, fiat face leading in the direction of bit rotation and disposed as a plane axially and approximately radially of the bit body through the original tooth cutting edge and the outer long edge corner of the block. As so conditioned, the axially-directed chisel edge of the block 27 becomes the percussively-penetrative, cutting edge of the associated tooth, the narrow angle chisel edge and the character of the block material enhancing the cutting efficiency and prolonging the useful life of the tool, while the form and particular disposition of said chisel edge conditionsit to perform a scraping action on the end face of the bore as an incident of tool rotation, with consequent gain in the penetrative efficiency of the tool. In the embodiment of the invention shown in Figures 3-6, inclusive, any projection of a block 27 radially of the bit body and beyond the outer end of an associated tooth 24 is ground away to bring the block exterior end into smooth conformity with the adjacent body and tooth exterior wall, in which relationship the radially-outward, wear-resistant end corners of the block 27 protectively overlie the associated tooth 24 outer corner to minimize abrasive wear of the latter and to maintain the initial bit diameter determinative of desired bore size.

The slightly-flared tooth corners of the conventionaltype bit 20 have an aggravating and time-consuming tend ency to catch and hang on the rough bore walls when the tool is shifted axially of the bore, particularly during retraction of the tool assembly from the bore, and this tendency, present even when the tooth edges are armored by means of the blocks 27, increases during operation of the block-armored bit due to abrasive wear of the tooth corners and consequent gradual exposure of the harder block 27 ends as projections beyond the adjacent abraded body and tooth end surfaces, hence a further feature of the invention is the provision of means reactive to normal bit operation to true and smooth the bore, to minimize wear of the bit body and tooth surfaces in contact with the bore walls, and thus to largely eliminate the objectionable tendency above mentioned. This further feature is developed through the provision of blocks 29 of suitable alloy material, similar to or the same as that characterizing the blocks 27, fixed to exterior surfaces of the bit 20 body, preferably in the flutes thereof, to function as reaming agents during rotation of the bit. As represented in Figures 3, 4 and 5, the blocks 29 may be rectangular units of appropriate length, width and thickness each seated in a flute 25 of the bit body with its length paralleling the bit body axis, its end adjacent the bit working face disposed inwardly along the bit body from and in clearing relation with the base of the notch between the adjacent bit teeth 24, and preferably with its side trailing in the direction of bit rotation closely adjacent the rotationally trailing side of the flute 25 wherein it is seated. Mounted upon the bit 20 body in the relation with a fiute 25 thereof shown and described, each of the blocks 29 is fixed and secured to said body, as by means of welded fillets 30 engaging between leading and trailing sides of the block and the adjacent body surfaces, or the like, to present an outer edge cornerof the block leading in the direction of bit rotation as a reaming cutter elfective to smooth and true the bore wall in reaction to bit rotation incidental to power drive thereof. The blocks 29 are conditioned, either through initial selection or by means of grinding subsequent to their mounting on the bit body, to so outstand radially from the bit 20 body as to define an orbit of outer corner rotation slightly smaller than that of the bit tooth and block 27 outer end corners and slightly larger than that of the bit body exterior surfaces, whereby to concentrate the abrasive effects of bit operation on the exposed surfaces of the blocks 29, rather than upon the bit body surfaces, and to minimize any tendency of the blocks 29 to wedge or stick in the bore. Promotive of the reaming action of the block 29 outer corners leading in the direction of bit rotation, a shallow groove or channel 31 is formed in the block 29 radial face leading in the direction of bit rotation adjacent and to parallel said outer leading corner, whereby to constitute said corner as a chisel edge of enhanced cutting efficiency and susceptible of ready rehabilitation after wear.

In the modified arrangement according to Figures 9 and 10 the characteristic elements of the improved organization are functionally and structurally the same as those hereinabove described, the only variation presented by the modification being one of arrangement exemplified as a skewed mounting of the blocks 29 re sulting from an inclined, rather than a parallel, relation between the block 29 lengths and the bit body axis which, in an appropriate like pitch of said blocks relative to the axis of rotation, imparts a slicing effect to the shear action of the block cutting corners and operates as an auger to retract cuttings away from the bore face.

In the modification according to Figures 7 and 8, the tooth arming blocks 27 are replaced by structurally similar and functionally identical blocks 27 fixedly associated with the teeth 24 of the bit as previously described, the said blocks 27 of a given bit assembly being alike in a uniformity of length greater than the radial length of the tooth edges on which they are mounted so as to each project outwardly and radially of the bit beyond the associated tooth in and as a cutting end determinative of the effective bit diameter. Cooperating and in backing support with the projecting ends of the blocks 27', and in substitution for the blocks 29 of the earlier embodiment, longitudinally-tapered blocks 29 of alloy material are fixed on and welded to outer end faces of the teeth 24 with the thicker ends of said blocks 29 conformably abutting under the block 27 end projections and their thinner ends directed away from the bit working face, the slope due to the taper of said blocks 29 providing the desirable slight fiare of the bit tooth outer corners. While it is feasible to dispose the blocks 29 with their lengths paralleling the bit body axis, it is preferred that said blocks be similarly skewed relative to said axis, as illustrated, to thereby develop the cuttings retraction effect characteristic of the modification shown in Figures 9 and 10.

The improved bit, in use, is marked by enhanced cutting efiiciency, extended useful life, ease of rehabilitation, effective removal of cuttings from the bore face, smooth, true bores, and freedom from tendency of the tool to stick, catch, or hang on the bore walls; it being also noteworthy that the blocks 29 and 29' also provide guided support for the bit and thereby conduce to straight bore development.

Since changes, variations, and modifications in the form, construction, and arrangement of the elements shown and described may be had without departing from the spirit of my invention, I wish to be understood as being limited solely by the scope of the appended claims, rather than by any details of the illustrativeshowing and foregoing description.

I claim as my invention:

1. In a drill bit of the character described having a frusto-conical body formed with integral, axially and outwardly converging, symmetrically-sloped teeth definitive of angularlv-spaced cutting edges radially of a working face on the greater end of said body and flutes longitudinally relieving the body conical surface between outer ends of said teeth, blocks of hard, wear-resistant, alloy material overlying and afiixed to the slopes of said teeth trailing in the direction of bit rotation, and chisel cutting edges on said blocks defined by a plane axially and radially of the bit body through the forwardly-directed edge of each block and the associated tooth apex in intersecting relation with the exposed block surface.

2. The organization according to claim 1, wherein said blocks are affixed to their respective tooth mountings by weld fillets filling the angle between the tooth surface and the block edge trailing in the direction of bit rotation and overlapping upon the otherwise-exposed, adjacent block surface.

3. In a drill bit of the character described having a frusto-conical body formed with integral, axially and outwardly converging, symmetrically-sloped teeth definitive of angularly-spaced cutting edges radially of a working face on the greater end of said body and flutes longitudinally relieving the body conical surface between outer ends of said teeth, blocks of hard, wear-resistant, alloy material overlying and aflixed to the slopes of said teeth trailing in the direction of bit rotation, chisel cutting edges on said blocks defined by a plane axially and radially of the bit body through the forwardly-directed edge of each block and the associated tooth apex in intersecting relation with the exposed block surface, and other blocks of alloy material spaced angularly about and aflixed to the body peripheral surface for bore-reaming action incident to bit rotation.

4. The organization according to claim 3, wherein said alloy material blocks on the body peripheral surface are seated and welded-aflixed in the body flutes to dispose their outer edge corners leading in the direction of bit rotation as cutting edges definitive of an orbit slightly less in diameter than the effective area of the bit working face.

5. The organization according to claim 3, wherein said alloy material blocks on the body peripheral surface are seated and weld-aflixed in the body flutes to dispose their outer edge corners leading in the direction of bit rotation as cutting edges definitive of an orbit slightly less in diameter than the effective area of the bit working face, and faces of said blocks leading in 5 the direction of bit rotation are grooved adjacent their outer corners to constitute said corners as chisel-type cutting edges.

6. the organization according to claim 3, wherein said alloy material blocks on the body peripheral surface are seated and weld-affixed in the body flutes in correspondingly-skewed relation with the bit axis of rotation for auger-like retraction of cuttings away from the bore face as the bit is rotated.

7. The organization according to claim 3, wherein the alloy material blocks afiixed to the bit teeth similarly end-project radially and outwardly beyond their respective mounting teeth and the alloy material blocks on the body peripheral surface are seated and weldaflixed on the outer ends of said teeth in conforming end engagement and buttressing relation with the projections of said first blocks.

8. The organization according to claim 3, wherein the alloy material blocks afiixed to the bit teeth similarly end-project radially and outwardly beyond their respective mounting teeth and the alloy material blocks on the body peripheral surface are seated and weldaffixed on the outer ends of said teeth in conforming end engagement and buttressing relation with the projections of said first blocks and in correspondinglyskewed relation with the bit axis of rotation for augerlike retraction of cuttings away from the bore face as the bit is rotated.

9. The organization according to claim 3, wherein the alloy material blocks aflixed to the bit teeth similarly end-project radially and outwardly beyond their respective mounting teeth, the alloy material blocks on the body peripheral surface are longitudinally tapered from a thicker and to a thinner end, and said latter blocks are seated and weld-affixed on the outer ends of said teeth in conforming engagement and buttressing relation of their thicker ends with the projections of said first blocks.

References Cited in the file of this patent