Rotary bit

June 21, 1938.

R. J. KILLGORE

ROTARY BIT Filed March 19, 1935

2,121,202

Sheets-Sheet 1

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June 21, 1938.

R. J. KILLGORE ROTARY BIT Filed March 19, 1935

2,121,202

Sheets-Sheet 2

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Patented June 21, 1938

2,121,202

UNITED STATES PATENT OFFICE

2,121,202 ROTARY BIT Robert J. Killgore, Los Nietos, Calif. Application March 19, 1935, Serial No. 11,801

Claims.

My invention relates to rotary drill bits, and relates in particular to a rotary bit especially adapted for the drilling of formations which are of a character too hard or tough for efficient 5 drilling with ordinary drag type drill bits and are not sufficiently brittle to be readily disintegrated by roller type bits.

We find that in certain fields formations are encountered which are of the character of shale 10 and appear to be somewhat rubbery in nature so that they resist penetration of the cutting edges of drag type and disc bits, with the result that the bits have a tendency to slide over the surface and wear away without accomplishing 15 any appreciable downward advance. Likewise, these formations do not chip and shatter when operated upon by roller type bits, with the result that drilling progress is retarded.

, An object of my present invention is to pro20 vide a rotary bit having teeth on the cutting members thereof which will penetrate this type of formation and also harder and softer formations, these teeth being produced on the cutters of the bit in a new manner.

A further object of the invention is to provide a rotary drill having a cutter member with openings facing the formation to be penetrated, and hard metal inserts carried in these openings in such a manner that breakage thereof will not readily occur. In the preferred practice of the invention the openings are tapered inwardly, and the hard metal inserts are likewise tapered so that when they are placed in the openings they will be held under radial compression by 35 the surrounding metal. Furthermore, it is preferable when severe operating conditions are encountered to make the inserts of such length relative to the depth of the openings that the inserts will not bottom in the openings but will 40 be held in place by the gripping action of the surrounding metal wall.

A further object of the invention is to provide a rotary disc bit having cutter discs formed of a tough metal, such discs having hard metal ⁵ inserts supported in the periphery thereof in the manner described in the preceding paragraph.

A further object of the invention is to provide a disc for a rotary bit having a combined digging ₅₀ and scraping action. This disc is characterized by having the periphery thereof divided into consecutive portions which are alternately provided with teeth for penetration of the formation so as to scratch the same and curved cutting 55 blades for scraping from the bottom of the hole (Cl. 255—71) the particles of the formation which have been loosened by the teeth.

It is a further object of the invention to provide a disc cutter for a rotary bit having teeth in the periphery thereof formed between notches 5 which are disposed at an angle relative to the face of the disc, the angle of such notches corresponding to the angle of drag of the periphery of the disc relative to the formation during the operation of the disc bit in its customary manner. 10

A further object of the invention is to provide a rotary cutter for a bit having hard metal inserts placed therein, the outer ends of such hard metal inserts being shaped to wedge form at angles relative to the axis of rotation of the 15 cutter;

A further object of the invention is to provide a cutter for a rotary bit having a large quantity of hard metal supported in position to reinforce or produce the cutting edge. In the practice of ₂o my invention the bodies of hard metal are of large size, and in the ordinary use of the invention the placing of hard metal on a cutter of definite size gives such cutter a greater quantity of hard metal than is ordinarily placed on the 25 cutter in the ordinary practice of hard-facing rotary cutters with either particles of hard metal or facings of welded material embodying a powdered or granulated hard metal.

A further object of the Invention is to provide 30 a rotary cutter having hard metal bodies carried therein which are cast in the openings or recesses of the cutter body. .

Further objects and advantages of the invention will be made evident throughout the follow- 35 - ing part of the specification.

Referring to the drawings, which are for illustrative purposes only,

Fig. 1 is a side view of a rotary disc bit embodying my present invention. 40

Fig. 2 is a fragmentary, partly sectioned detail to enlarged scale showing the lower portion of a disc cutter included within the area circumscribed by the dotted line 2 of Fig. 1.

Fig. 3 is a view looking upwardly toward the 45 lower edge of Fig. 2.

Fig. 4 is a view similar to Fig. 2, showing the lower portion of a rotary disc cutter having multiple rows of inserts forming teeth on the periphery thereof. 50

Fig. 5 is a fragmentary view looking upwardly toward the lower edge of Fig. 4.

Fig. 6 is a fragmentary view showing the lower portion of a disc bit having teeth formed in-the periphery thereof by notches, said teeth being 55

3,121,202 provided with cutting reinforcement in the form of hard metal inserts.

Fig. 7 is a view looking upwardly at the lower edge of Fig. 6.

Fig. 8 is a fragmentary perspective view showing another manner of forming a toothed cutter of the character shown In Figs. 6 and 7.

Fig. 9 Is a face view of a combination scraping and digging disc.

Fig. io is a perspective view of a drag type biv embodying the principles of my invention.

Fig. 11 is a view of a roller type rotary drill cutter of the character used on cone roller rock bits.

Fig. 12 is an enlarged fragmentary sectional view showing a type of insert which may be employed in the cutter shown in Fig. 11 and in other of the cutters disclosed where such cutters are to be used in extremely hard formations.

Although my invention is useful in the various types of rotary cutters hereinafter to be described, it is of especial utility in disc bits of the character shown in Fig. 1 wherein a bit body 15, adapted to be secured to the lower end of a 25 drilling string IS, supports cutter discs 17 which are adapted to rotate on bearing members 18 carried by the lower portion of the bit body 15.

As shown in Figs. 2 and 3, the cutter discs 17 each comprise a circular body 19 of tough steel 30 having a cylindrical circumferential face 21. , Extending inwardly from the face 21 are tapered openings 22 and 23 which carry tapered hard metal inserts 24 and 25 in such positions that the outer ends 26 thereof form radially project35 ing teeth. The type of hard metal employed in the inserts depends upon tlie character of the formation to be penetrated. For example, if the formation is relatively soft, even though gummy or rubbery as in shale, these inserts may be made 40 from stellite or some other air-hardening alloy.

An especial advantage of the construction shown in Figs. 1 to 3 is that the metal components of the disc 17 may be assembled without use of processes or treatment which will be detrimental 45 to the grain structure of the metal or place strains therein by the unequal distribution of heat. It has been a practice to make a disc of the shape shown at 17 from a good grade of steel and to apply hard metal thereto by weld60 ing processes. Very naturally, the particles of hard metal employed and the body 19 of such disc are not benefited by the application of welding heat thereto. In my new disc 17 the openings 22 and 23 may be formed, and the 55 body ί 9 may then be hardened. After the hardening operation, the inserts may be placed without application of heat which will weaken the same.

The Openings 22 and 23 are respectively deeper 60 and longer than the portions of the inserts 24 and 25 which are placed therein so that the inner ends of the inserts do not strike the bottoms of the holes or openings 22 and 23. Accordingly, these inserts are held in place by the 05 gripping effect of the metal of the body 19 surrounding the openings 22 and 23, which gripping effect not only prevents inward movement of the inserts 24 and 25 but at the same time holds them under radial compression, which mini70 mizes shattering and breakage of the inserts. It will be understood, however, that in discs 17 adapted for soft digging, where the inserts 24 and 25 are not subject to severe axial forces, the inserts may be bottomed in the openings 22 and 75 23. Likewise, in the manufacture of some discs the openings and the inserts may be both made untapered or cylindrical, and such inserts may be placed in the openings while the body 19 is heated to a medium temperature, the subsequent cooling of the body 19 causing the metal walls 5 of the openings to shrink around the inserts and securely hold them in the openings.

An additional feature of the invention resides in the forming of wedge or chisel points 27 on the outer ends 26 of the inserts 24 and 25, these 10 chisel points 27 being disposed, as shown in Fig. 3, at angles a relative to the face of the disc 17. The angle a corresponds in general to the direction of movement of the periphery of the disc 17 across the formation 28, Fig. 1, forming the bot- 15 tom of the hole 29 which is being drilled, this direction of movement being indicated by the arrow 20 of Fig. 3 and ordinarily being approximately 20° relative to the axis of the disc 17.

As shown in Fig. 2, the openings 22 and 23 20 are alternated, and the openings 23 are of less depth than the openings 22, for the purpose of enabling the placing of the openings 22 and 23 relatively close together without too thin a metal wall being formed between the inner ends 25 thereof. The inserts, placed as shown in Figs. 1 to 3, are forced into the formation 28 so that as the disc rotates with a combined revolving and sliding movement, the face of the formation is scratched up and disintegrated. Tests which 30 I have made indicate that in shale formations such as those hereinbefore mentioned, the disc cutters 17 will drill from two to four times faster than standard disc bits and roller type bits.

Where the formation to be penetrated is of 35 more abrasive character, the disc may be provided with a larger number of hard metal inserts. This may be accomplished as disclosed in Figs. 4 and 5, wherein I have shown a portion of a disc 30 having a relatively wide peripheral 40 face 31 in which two rows 32 and 33 of inserts 34 are placed in staggered relation. These inserts project so as to form penetrating teeth and are sharpened on the projecting ends, as shown.

Another feature of the invention is to provide 45 a disc cutter having peripheral teeth formed by or between peripheral notches which extend diagonally with relation to the face of the disc. In Figs. 6 and 7 I show a portion of a disc 35 having diagonal notches 36 cut therein, each 50 notch being at an angle b relative to the axis A—A of the disc 35. The angle b in this form of the invention is also the approximate angle of movement of the periphery of the disc relative to the formation and ordinarily is about 20° 55 relative to the axis A—A of the disc 35. A further feature of this form of disc is that the teeth 38 are given cutting reinforcement. In other words, the ability for these teeth to cut is reinforced by the placing of hard metal bodies in 60 the disc 35 in such position that the hard metal bodies will be aligned with the outer portions or point portions of the teeth 38. Accordingly, in each tooth a radial opening 40 is drilled inwardly, and a hard metal insert 41 is placed in 65 each opening as disclosed.

As shown in Fig. 8, a disc cutter 42 may have the teeth 43 thereof reinforced for greater cutting ability by hard metal bodies 44 placed on or in the face 45 of the disc 42 by the known 70 processes, such, for example, as welding. In the disc 42 the teeth 43 are formed between notches or slots 46 which are helical with relation to the axis of rotation of the cutter 42, and such slots 46 are likewise formed at an angle corre- 75

2,121,302 spending to the angle of movement of the periphery of the disc relative to the formation which is being penetrated, such angle being ordinarily 20° relative to a plane coinciding with the axis of ro5 tation of the cutter.

In soft but rubbery formations, and in other formations also, the drilling action by roller type cutters is often retarded by the presence of the cuttings on the bottom of the hole, the ¹⁰ roller cutter rolling upon these cuttings and therefore penetrating the formation but little. For use in formations of this character my invention provides a disc cutter 41, such as shown in Fig. 9, having alternate digging and scraping ¹⁵ edges 48 and 49 so that as the disc rotates on its axis, it will first present teeth to the formation to dig into and break up the surface and will then apply a scraping blade to remove the cuttings which have been formed by the digging 20 teeth, so that the full effect of the subsequent application of digging teeth may be realized. Ilie disc 47 is accordingly provided with alternate arcuate edges 51 and 52, the edges 52 projecting radially beyond the edges 51 a dis²⁵ tance substantially equal to the length of teeth 53 which are formed along the edges 51 so as to provide the disc 41 with digging segments 48. These teeth 53 are preferably formed by use of hard metal inserts carried in openings ³⁰ in the disc 47 in the manner shown in Fig. 2.

The scraping or blade portions 49 of the disc may be given reinforcement either as shown at 54 by the application of hard metal on the face of the disc or as shown at 55 by the placing 35 of hard metal inserts 56 with the outer ends thereof flush with the peripheral edges 52.

It is a feature of the invention to cast hard metal bodies, such as shown at 56 in Fig. 9, in the openings of the cutters. In this process of 40 reinforcing the cutting edge of a rotary bit cutter, the cutter body is provided with openings and is heated. The openings are then filled with molten hard metal, such, for example, as tungsten carbide, air-hardening steels, etc., which 45 bonds itself to the walls of the openings and therefore forms a hard metal insert which is in proper operative position and which cannot be removed from the opening in which it resides. Such inserts as shown at 44 in Fig. 8 and at 64 50 in Fig. 10 may be applied by use of the above set forth method of casting.

Although I have but little doubt that my invention is of greatest utility with roller types of rotary drilling bits, it must be recognized that 55 the principles thereof may be used in what are known as “drag bits” such as, for example, fishtail bits. In Fig. 10 I show a drag bit patterned after the later types, in which a bit body 57 has a plurality of blades 58 and 59 projecting 00 downwardly therefrom in radial relation. In drag blades of this character hard metal inserts may be mounted.in such a manner that greater cutting ability or reinforcement will be given the cutting edges of the blades. Likewise, such in65 serts may be erased to project from the blades so as to definitely provide teeth. In Fig. 10 I show a drag bit with scraping blades 58 and digging blades 59. The digging blades 59 have inserts 61 mounted therein after the manner dis70 closed in Fig. 2, so as to provide projecting digging teeth, and the blades 58 are provided with hard metal edges 62, preferably welded in place, to act as scrapers for removing from the bottom of the hole the cuttings which have been pro75 duced by the digging action of the inserts 61.

To assist in maintaining the gauge of the bit, hard metal inserts 64 may be placed in the edges of the blades of the drag bit. Illustrative of this, I have shown the inserts 64 in the edges of the scraping blades 58. It will be noted also 5 that each of the digging blades 59 has a trailing outer edge 65 in which hard metal inserts 66 are mounted in downwardly and outwardly extending diagonal relation so that the projecting ends of these inserts 66 will definitely define the ¹⁰largest dimension of the bit. Naturally, as these inserts 66 are worn away, the inserts 64 will assist in maintaining the gauge of the hole.

Although I have not made reference to the same, it is to be understood that all rotary bits 15 with which the principles of my invention may be employed shall have the customary passages for drilling mud so that streams of drilling mud will be directed in such a manner as to efficiently remove the cuttings from the hole. In 20 Fig. 10 the perspective view of the bit body 57 permits the showing of a mud discharge orifice 67 of the general character employed.

For penetration of extremely hard formations, such as rock, roller cutters of cylindrical and con- 25 ical form are employed. In Fig. 111 show a conical cutter 68 of the type employed on rock bits, these cutters comprising a; body 69 of relatively tough and hard metal having a plurality of hard metal inserts 25α secured therein in such position ³⁰that the projecting ends thereof will form teeth which will produce a grinding action on the hard material forming the bottom of the hole which is being drilled. As shown, these inserts are preferably placed in staggered relation so that 35 they will not drag as the cutter 68 is rolled over the bottom of the hole.

Where the formations operated upon are of extremely abrasive character, the wearing away of the cutting teeth may be minimized by the use 40 of diamond-metal points. This diamond-metal, approaching close to the natural diamond in hardness, is likewise very brittle, and in many bits is broken away from the supporting structure instead of wearing away, the result being 45 that the expected cutting effect is not obtained. In Fig. 12 I show a composite insert 70 which may be employed under conditions such as those set forth above in this paragraph. This insert comprises a tapered body 71 of hard metal, such_v 50 for example, as one of the tough and hard, high . speed, or air-hardened alloys. In the outer end 72 of the tapered body 71 a smaller tapered opening 73 is formed to receive a tapered insert 74 of diamond-metal, such, for example, as tung- 55 sten carbide, etc. In Fig. 12 I have shown a small portion) 75 of a bit cutter with a tapered opening 76 therein to receive the tapered bouy 71. The inner end of the opening 76 is rounded so that no sharp corners are formed wherein a ⁶⁰crack may start. The diameter of the opening 76 is such that the insert 71 does not bottom therein, but instead the insert 71 is held by the tapered side walls of the opening 76 for exerting great radial inward pressure against the insert 65 71 to reinforce the metal structure thereof against shattering due to the heavy strains which may be applied during the drilling operation. The same condition is preferably produced relative to the mounting of the diamond-metal in- 70 sert 74 in the tapered opening 73 of the larger insert 71 so that the diamond-metal insert 74 is •securely held in cutting position and in such a maimer that the tendency for the same to shatter is minimized. ⁷⁵

9,121,209

Although I have herein shown and described my Invention in simple and practical form, it is recognized that certain parts or elements thereof are representative of other parts, elements, or ₅ mechanisms which may be used in substantially the same manner to accomplish substantially the same results; therefore, it is to be understood that the invention is not to be limited to the details disclosed herein but is to be accorded the I ο full scope of the following claims.