US2151544A - Composite bit - Google Patents

Description

UNITED STATES Search PATENT OFFICE COMPOSITE BIT John A. Zublin, Los Angeles, Calif.

Application February 21, 1938, Serial No. 191,621

13 Claims.

The present invention relates generally to rotary well drilling bits such as are used to drill oil wells and the like, and more particularly to drill bits of the general type described in my on the formation causes the carrier to rotate with respect to the shank and thereby successively and intermittently cause the rollers to contact with the formation with a rolling motion thereon. 'I'he general principles underlying the type of drill bit under consideration will be found in my Patent No. 2,050,988.

In the i'lrst mentioned patent, a plurality of carriers is used, the cutters on each carrier contacting the bottom of the hole on opposite sides of the bore axis. This arrangement prevents any of the cutters from coming into coincidence with the axis of the hole when the cutters are in their bottommost position. The second mentioned patent (No. 2,069,799) is provided with only a single carrier which is preferably inclined to the horizontal. The inclination will normally cause the bottommost roller to contact with the formation to one side of the hole axis and will thereby insure rotation of the carrier about the inclined axis so long as the shank is being rotated.

In view of the fact that drill bits of the type under consideration form a hemispherical bottom in the formation, drilling weight on the bit would tend to move the bottommost roller into coincidence with the hole axis. If this were to occur, rotation of the carrier in the manner aforementioned would practically cease. To overcome this possibility it has heretofore been proposed to provide a thickened leg portion on the shank which will bear against the sides of the hole and prevent the bottommost roller from moving into a position coincident with the hole axis. The thickened leg portion is` an eiective instrumentality for insuring carrier rotation. But it also introduces wear on the leg caused by its thrust against the formation. It is with the end in view of decreasing or eliminating the wear on the shank, as the leg portion thereof, and in maintaining the bottommost roller from coincidence with the hole axis that the present invention is concerned.

Accordingly, it becomes a general object of this invention to. provide an improved drilling bit specially adapted for use in hard formations.

A further object of the invention resides in the provision of an improved bit having separated digging and reaming portions.

A further object of the invention involves a bit in which the side thrust on a shank is absorbed by reaming rollers.

Still another object of the invention is to provide a bit wherein the bottom contacting rollers are maintained to one side of the hole axis by upper reaming rollers.

` A further object of the invention lies in the provision of a bit which will be self-stabilizing in the hole and which will prevent the production of an undergauged bore.

A further object of the invention lies in the provision of improved flow channels for maintaining reaming rollers free from cuttings While at the same timev assisting their rotation about their own respective axes.

Another object of the invention is to arrange reaming roller cutters on a drill bit in such manner as to permit the use of a larger channel for the passage of drilling fluid.

Still another object of the invention is to arrange reaming roller-cutters non-uniformly circumferentially of the drill bit to allow the use of a iiow channel of enlarged cross-sectional area.

How the above and other objects and advantages of my invention are secured will be better understood by reference to the following description and the annexed drawing'in which:

Figure 1 is an elevation of the composite bit with parts thereof being shown in section;

Figure 2 is a side elevation of the drill bit as seen from the right of Figure 1; and

Figure 3 is a section along the line 3--3 of Figure l.

In general, the drill bit includes a lower cutting portion A and an upper reaming portion B. The former is substantially the same as that described in my copending application entitled Compact bits filed February 21, 1938, Serial No. 191,622.

Inasmuch as it is not by itself being claimed in this application the various parts and the advantages of the arrangement shown will not be described in particular detail.

The lower portion of the bit includes a plurality of depending legs I l, l2 extending from the shank body l0, the upper end of which carries the usual threaded pin I3 for connecting the drill bit with the drilling string. One of the legs Il has formed integrally therewith a bearing supporting member therein for establishing communication between extension I5 fitting into a bore I3 formed in the the shank passageway 33 and the nomle 34. The leg I2 of the shank, which leg, after the cutter fluid will issue from this lower nozzle and sweep assemblyhas been placed on the bearing supporting member, can be welded at its upper end I2a to the shank body proper and at its lower region I2b to the reduced extension I5. The cutter assembly includes a cutter carrier II provided with a plurality of circumferentially spaced slots I3 which are bridged by bearing pins I3 welded to the side portions 20 of the Slots, each pin carrying one or more formation contacting rollers 2l. The carrier I1 is provided with a plurality of ball bearing raceways 22 in an inner bore 23, which are adapted to cooperate with an inner bearing race 24 containing complementary torio raceways 25. Between the raceways are provided balls 26 which will serve to transmit bearing loads between the carrier and inner race.

Prior to the placing of the separate long leg I2 on the reduced bearing supporting extension I5 and its welding thereto and to the shank body, the carrier II with the cutters 2I and pins I9 thereon is placed over the inner race 24 and the bearing balls 26 introduced into the raceways 22, 25 through the holes 21 formed within the inner race and communicating with respective raceways. Thereafter. buttons 28 having an upper cylindrical portion 28a and a lower rectangular portion 28h are inserted into the bores, serving to prevent the balls from falling from the raceway while at the same time providing a substantially continuous raceway on which the balls can roll as the carrier rotates. The lower portion 28h of the buttons is made rectangular in shape so as to be capable of riding in the keyway 29 formed in the bearing supporting member, and thus serving to lock the inner race 24 from rotation with respect to the bearing supporting member I4. As explained in my applica.- tion above referred to, the buttons serve the three-fold function of providing a substantially uninterrupted raceway, preventing the balls from falling from the raceway, and keying the inner raceway to the bearing supporting member.

Upon assembly of the carrier I1 on the main bearing and the insertion of the buttons 28 in the manner aforementioned, this entire assembly is slid over the bearing supporting member with the rectangular button heads riding in the key- Way. Thereafter, the long leg I2 is placed over the reduced extension I5 with the boss 30 on the leg abutting the end of the inner race, and causing the opposite end of the race to abut against the boss 3I formed on the other leg II extending from the shank. Upon welding the upper part of the leg I2a to the shank III and the lower part to the reduced extension I5, a rigid shank assembly results for carrying the cutter assembly for rotation with respect to the shank about an inclined axis D-D with the bottommost roller 2 Ia positioned to one side of the axis E-E of the hole.

As described in my copending application, an upper nozzle 32 is placed in the shank communicating with and receiving drilling fluid from the passageway 33 provided in the shank. The nozzle will effect a discharge of fluid against successive cutters as they pass under it, the force of the fluid rotatil1E .ea.ch.`- tter about its own axis to insure that all of the teeth or cutting e g transversely across the hole bottom for eectively removing the detritus.

The upper portion B oi' the bit constitutes a reamer. A plurality of slots 36 is formed in the shank body with the ends of each slot terminating in a plurality of notches or grooves 31, each of which receives a bearing pin 38. Each bearing pin carries one or more reamer roller cutters 39a, 39h having teeth thereon, although, if desired, disc or other cutters can be used. 'I'he rollers in each set are mounted upon their pin, which is then inserted in the notches 31 of the shank. The ends of the pins are welded in the groove to effect a rigid attachment of the pins to the shank body while permitting free rotation o'f the rollers on the pins. In the specific illustration contained on. the drawing, two sets of rollers are provided at substantially dismetrical portions of the shank. However, the number of rollers may be varied without departing from the scope and. spirit of the invention.

One of the main features of the invention resides in positioning the rollers 39a at the right of the drill bitl (as seen in Figure 3) so that by their contact with the formation they will maintain the bottommost rollers 2Ia at the lower portion of the bit from coincidence with the hole axis. 'I'hat this will occur will become apparent from a mere inspection of Figures 1 and 3. As the drilling tool rotates, the reaming rollers will move around on the formation, maintaining the hole to gauge, and because oi their engagement with the sides of the hole will position the bottommost rollers 2Ia to the side of the hole axis opposite to the position of the reamer rollers. It will be noted further that the shank leg I2 is spaced from the sides of the hole, and will be maintained in the spaced position by the engagement of the upper reamer rollers 33a with the formation throughout substantially the entire drilling life of the tool. 'This will prevent Wear from occurring on this leg, or decrease the wear. Similarly, wear upon the other leg II depending from the shank will be prevented by the other sets of rollers 39h which, by their contact with the sides of the hole, will maintain this leg spaced from the formation.

As stated before, the number of reamer rollers can be varied. Thus, even a single roller, or a single set positioned on that side of the hole axis opposite to the position of the bottommost hole contacting roller 2Ia will maintain such contacting position and eliminate wear upon the long leg I2 depending from the shank. Moreover, one or more larger or smaller diameter reamer rollers can be used to alter the contact position of roller 2Ia as regards the hole axis, and also to change the final diameter of the bore.

The reamer rollers are kept free from cuttings by the incorporation of a plurality of nozzles 40a, 40h threaded into the shank and communicating with the passageway 33 in the shank body. Fluid will issue from the small nozzles and engage against -all parts of each roller cutter since each cutter will rotate about its bearing pin and during this movement Will position all of its cutting parts in the path of the stream issuing from the areeifectively cleaned. The cuttings are removed nozzle. Each nozzle is positioned so as to direct om the bottom of thehole by discharge of fluid ts discharge to one side of the axis of the roller m a nozzle 34ffthreaded\hel in the lower upon which it acts in the direction of rotation of the roller. 'I'he leading rollers on each side of the shank as regards rotation of the bit will have an inclined uid stream issuing from the nozzles 50a. By virtue of this design the fluid streams tend to assist rotation kof each A.roller about its axis and at thesame time thorougly Aflushes all cutting parts thereon.

The reamer rollers 39a and 39h rare preferably spaced unequal distances apart circumferentially of the reamer portion of the bit. The rollers 39a.

are adjacent one another, as are the rollers 39h,

leaving substantial circumferential distances be.-l

tween the pairs of rollers 39a and 39h. This arrangement provides a stabilization of the reamer and the bit as a whole in the hole; while allowing large spaces between the respective pairs of rollers through which the detritus and drilling uid can pass upwardly from the bottom of the hole.

In connection with the non-uniform circum- 39b, it is possible to use larger rollers with correspondingly bigger teeth for producing a round hole of any definite diameter, and despite the use of such large reaming roller cutters, ample shank material can be allowed between the grooves in which the cutters are mounted and the passageway 33 conducting drilling uid from the drill pipe to the various parts of the bit and bottom of the hole. Despite the provision of adequate shank material, the .cross-sectional 'area of the flow channel or uid passageway 33 can be much greater than is obtainable when equal circumferential spacing of rollers about the bit is used.

Whenever such equal spacing is used, the passtantially at right' angles to the central plane ofthe reaming cutters presently disclosed (see Figure 3).

While the inventionhas been described with particular reference to the embodiment shown on the drawing, it is to be understood that changes. i

may be made in its construction and arrangement of parts without departing from the intent and scope of the invention, and consequently, the foregoing description is to be considered illustrative of rather than restrictive upon the claims appended hereto.

I claim:

l. An earth-boring tool, comprising a shank, a plurality of cutters rotatable with respect to said shank, means mounting said cutters on .said

shank for bodily translation with respect to said shank whereby said cutters are positioned to one side of the bore axis when in their lowermost position in the bore, and reaming means mounted on said shank to maintain said cutters to said one side of said axis. l

2. An earth boring tool, comprising a shankr adapted to be rotated about an axis by a drilling string, a cutter carrier rotatably mounted on said shank, a plurality of cutters rotatably mounted 'on the carrier for successive intermittent contact with the formation, said cutters being positioned to one side of the shank axis when in their lowermost position in the bore, and one or more reamer rollers carried by the shank for preventing each cutter when in its lowermost position from assuming coincidence with said axis.

3. An earth boring tool comprising a shank adapted to be rotated about an axis by a drilling string, a cutter carrier rotatably mounted on said shank about an inclined axis, a plurality of cutters rotatably mounted on the carrier for successive intermittent contact with the formation, said cutters being positioned to one side of the shank axis when in their lowermost position in the bore, and one or more reamer rollers carried by the shank for preventing each cutter when in its lowermost position from assuming coincidence with said axis.

4. An earth boring tool as defined in claim 2, in which said reamer rollers are positioned above said cutters and on the opposite side of the shank axis as regards the lowermost cutter positions.

5. A.An earth boring tool as deiined in claim 3, in which said reamer rollers are positioned above said cutters and on the vopposite side of the shank axis as regards the lowermost cutter fpositions.

6.,An earth boring tool, comprising a shank adapted to be rotated about an axis by a drilling string, a cutter carrier rotatably mounted on said shank, a plurality of cutters rotatably mounted on the carrier for successive intermittent contact with the formation, said cutters being positioned to one side of the shank axis when in their lowermost position in the bore, and reaming means mounted on said shank for preventing each cutter when in its lowermost position from assuming coincidence with said axis and for maintaining said shank free from contact withthe sides of the bore. l

, 7:-'An earth boring tool,.'comprising a shank adapted to be rotated about an axis by a drilling string, a cutter carrier rotatably mounted on said reamer rollers mounted above said cutters on' said shank for preventing veach cutter when in its lowermost position from assuming coincidence with said axis and for maintaining said shank free from contact with the sides of the bore.

8. An earth boring tool, comprising a shank having a plurality ofv depending legs, a cutter carrier rotatably mounted on said shank between said legs, a plurality of cutters rotatably mounted on the'carrier for successive intermittent contact with the formation, and one or more reamer rollers mounted on said shank above said legs for insuring rotation of said =carrier on said shank.

9.1An earth boring tool comprising a shank having a plurality of depending legs, a cutter carrier rotatably mounted on said shank between said legs, a plurality of cutters rotatably mounted on the carrier for successive intermittent contact with the formation, one or more reamer rollers mounted on said shank above said legs for maintaining at least one of said legs fromfcontact with the sides of the bore.

l0. An earth boring tool comprising a 'shank nrotatable about an axis and having a plurality of -on said shank above said legs and on different sides of the shank axis for maintaining said legs from contact with the sides of the bore.

11. A well reamer including a shank, and two substantially diametrically opposite pairs of rollerreaming cutters on the shank, the cutters ofv each pair being in circumferential adjacent relation and said pairs being spaced substantial distances apart circumferentially of the shank, and a fluid passageway in said shank between said pairs of rollers, said passageway being of noncircular cross-section elongated in the direction of -the circumferential spacings between said pairs of rollers.

12. A well reamer comprising a shank, a pair of roller reaming cutters on the shank, the cutters of said pair being in adjacent relation circumferentially of said shank, and one or more, roller reaming cutters positioned on the shank substantially diametrically opposite said pair of cutters and spaced substantial circumferential distances therefrom, and a fluid passageway in said shank between said rollers,l said passageway being of non-circular cross-section elongated in of cutters and said one or more cutters, the area of said cross-section being greater than that of a circular passageway enclosed by the same shank wallthickness.

JOHN A. ZUBLIN.

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