US2802643A

US2802643A - Reaming bit

Info

Publication number: US2802643A
Application number: US358272A
Authority: US
Inventors: Robert A Cunningham; Erwin A Morlan; Lyle L Payne
Original assignee: Hughes Tool Co
Current assignee: Hughes Tool Co
Priority date: 1953-05-29
Filing date: 1953-05-29
Publication date: 1957-08-13
Anticipated expiration: 1974-08-13

Description

1957 R. A. CUNNINGHAM EI'AL 2,802,643

REAMING BIT Filed May 29, 1955 37 Q I Robefl A. Cunninyhafi Erwin AMorlan Lyle L Payne I INVENTORS 0 BY I ATTORNEY States Patent Office 2,802,643 Patented Aug. 13, 1957 2,802,643 REAMING BIT Robert A. Cunningham, Erwin A. Morlan, and Lyle L.

Payne, Houston, Tex., assignors to Hughes Tool Company, Houston, Tex, a corporation of Delaware Application May 29, 1953, Serial No. 358,272 2 Claims. or. 255-330 This invention relates to reaming bits and has particular reference to a reaming bit which is run in a well bore to cut to gage an undersize hole which was drilled undersize by use of a smaller drill bit or by use of one which became undersize because of wear or distortion of parts.

In thev drilling of deep earth bores drill bits are subject to wear on both'the leading cutting elements and the gage cutting structure. Also frequently the drill bit is so damaged, while being lowered into a bore produced by, preceding bits, that drilling .accomplished by such a bit produces an undersize hole. If then'a new drill bit is lowered into the well bore to drill deeper, such drill bit is required to first ream a portion of the hole before reaching bottom. This reaming operation often produces such destructive effects upon the new bit that, when bottom is reached, it is necessary to withdraw and replace the bit with a succeeding new bit in order that a desired gage of hole is provided as drilling ahead is again resumed.

It is the primary object of the invention to provide a reaming bit that is capable of effectively reaming an undersize hole to bottom, so that the succeeding drill bit attached to the drill stem and used for drilling ahead will be in unimpaired condition when it reaches bottom and will therefore produce a maximum of additional hole of full nominal gage.

Another object is to provide a reaming bit having roller reaming cutters so mounted that the bit will efficiently cut to gage a large amount of hole thereby conserving bits designed for drilling ahead.

Still another object is to provide a reaming bit in which the cutters are so mounted that inward thrust of the cutters is effectively resisted.

Another and more specific object is to provide a reaming bit comprising a head having downwardly and inwardly extending shafts thereon, reaming cutters on said shafts and a thrust body to rigidify the structure and to assume at least a portion of the inward thrust upon the cutters during reaming.

Cln one form the invention also comprehends the use of antifriction hearings in the cutters so arranged as to assume both radial and axial loads and in this manner such bearings assume a portion of the inward thrust of the reaming cutters thus assisting in holding the cutters to gage.

It is also an object to provide a reaming bit having large, sturdy cutters with adequate clearances thereby facilitating the removal of cuttings from the vicinity of the bit.

Another object is to provide a structure in which flushing fluid may be jetted downwardly between cutters to facilitate disintegration of the earth formations and effectively remove the cuttings from the cutting structures.

These and other objects and advantages of the invention will be more fully apparent from the following description and the drawings in which:

Fig. 1 is a view, partly in section and partly in elevation, of a reaming bit embodying the invention;

Fig. 2 is a bottom plan view of the disclosed embodiment of the reaming bit, and

Fig. 3 is a bottom plan view of a modified form of thrust body comprising an element of the reaming bit,

The embodiment of the invention shown in the drawings is a three-cutter reaming bit, Fig. 1 showing a sectional view through one half of the bit, the other half of the bit being shown in elevation and the rolling cutter there shown being rotated into the plane of the paper to more clearly show the structure. The bit is shown at 1 and comprises a head 2 having a threaded pin 3 at its upper end for attachment to the lower end of a drill string. The head has three downwardly extending legs 4 each of which is provided with an inwardly extending shaft 5 terminating in a reduced end '6 upon which the thrust body 7 is mounted. Cutters '8, 9 and 10 are rotatably mounted on the shafts between the surfaces 11 and 12 on the leg 4 and the thrust body 7 respectively.

T he head 2 is preferably made up of segments as shown at 14, 15 and 16, these segments being integrally united, as by welding as is well known in the art, to complete assembly of-the bit. Each segment carries one of the legs 4 and the ass-ociatedshaft 5 upon which one of the cutters is mounted.

A's clearly shown in Fig. l the shaft 5 of the disclosed embodiment is composite in that the reduced end portion 6 is made up as a separate part press fitted into a complemental bore in the end of the outermost portion of the shaft. Such end portion has a cylindrical portion 31 intermediate its ends whereby there is provided an inwardly facing shoulder 36 to serve a purpose that will be further explained.

Since the shaft 5 extends both inwardly and downwardly the thrust body 7 is generally pyramidal in shape. Openings 17 in the respective faces 12 tightly receive the ends 6 of the shafts whereby the bit structure is made adequately rigid and there is provided an outwardly facing thrust surface at the inner end of each of the shafts.

The thrust body 7 is preferably multi-foliolate as best seen in Fig. 2. In a three-cutter structure, as shown, the body has three lobes as indicated at 20, 21 and 22. To further explain, the nether face of the body is channeled upwardly and outwardly from the axis of rotation of'the bit, as shown at 23, intermediate vertical planes passing through the longitudinal axes of openings 17 in the thrust body. The channels 23 interesct the outer faces of the body 7 upwardly from the nether face of the body and hence form the lobular or multifoliolate structure abovedes cribed. There is thus provided a structure of adequate strength and rigidity and at the same time the channels 23 serve to conduct cuttings and flushing fluid outwardly and upwardly so that the flushing fluid can remove the cuttings from the vicinity of the bit.-

The

cutters

8, 9 and 10 are generally disk like, shown as frusturn-s of cones, contoured internally complementary to the shaft 5 to form raceways to receive roller bearings 24 and ball bearings 25. The latter are insertible into their raceway, after the cutter and rollers have been assembled on the shaft, by way of the bore 26 in the bit leg 4- and they are held in assembled relation by means of a plug 27 secured in place as by means of welding as indicated at 28.

The cutters have an inwardly extending flange 30 at their innermost ends and this flange fits about the cylindrical portion 31 of the shaft. It also provides an inwardly facing thrust surface in confronting relation with the surface 12 on the thrust body 7. It seems apparcut that this structure serves to assume inward thrust of the cutters as the bit is rotated to effect reaming action. Such action is accomplished by the cutting action f the teeth 32 and the crushing or cutting action of the gage surfaces 33 to ream ahead and to maintain gage of the reamed hole. Since the ball bearings 25 are so arranged as to assume both radial and axial components of load a portion of the inward thrust is also borne by these hearings.

To enhance the wear resistant properties of the confronting thrust faces on the inner end of the cutter and the thrust body 7 these faces are grooved and filled with wear resistant metal 34 and 35.

Obviously the inner end 6 of the shaft may be a separate piece press fitted into a complemental bore in the inner end of the shaft as shown and already described, or the shaft may be an integral unit in the manner shown in U. S. Patent No. 1,983,316. In either event there is provided an inwardly facing shoulder 36 in engagement with the thrust face 12 on the body '7. This assures a fixed space within which the cutter is mounted to rotate upon the shaft 5. It also assists in providing a structure that is sufficiently rigid that it is capable of resisting both static and shock loads imposed from normal use of the bit.

To more fully understand the structure and operation of the disclosed embodiment it will be assumed that the

cutters

8, 9 and 10 are first mounted upon their respective bit head segments of which two are shown at and 16, it being understood that as many segments will be used as there are cutters on the bit.

The reduced end 6 of each shaft is then forced into its complementary opening in the thrust body 7. The segments are then in assembled relation and are integrally united, as by welding, to form the bit head 2. The assembled bit is then attached to the lower end of a drill string and is lowered to such level as reaming is to begin. Continued lowering and rotation of the bit progressively cuts away the ledge that is formed and at the same time the gage cutting structure or surfaces 33 maintain desired gage. Inward thrust of the cutters is assumed by the complementary thrust surfaces 34 and 3S and by the ball-s 25.

When reaming, the bore previously drilled ahead is usually filled with well fluids and detritus. To facilitate removal of such detritus, agitator or cutter blades 37 are provided on the nether face of the thrust body 7. Flushing fluid pumped downwardly through the passages 38 in the bit head picks up the cuttings and detritus about the cutters and the thrust body 7 and they move upwardly with the flushing fluid through the annulus in the well bore about the drill string to which the bit is attached. The channels 23 in the nether face of the thrust body 7 facilitate the movement of flushing fluid and detritus from about the bit. 9

*In Fig. 3 the thrust body 7 is' shown provided with an axial bore 40 which is bottomed where it transects 4 the openings 17. Hence the inner ends 6 of the shafts 5 are exposed within this bore. With this feature of construction it is intended that weld metal shall be deposited within the opening 40 to form an integral bond between the metal of the thrust body and the inner ends 6 of the shafts '5.

Broadly the invention comprehends a reaming bit that possesses sufiicient strength and wear resistant characteristics that it is capable of reaming to gage a large extent of undersize earth bore.

We claim:

1. In a reaming bit, a bit head, downwardly extending legs thereon, inwardly extending shafts on said legs, the inner end of each of said shafts terminating in a cylindrical portion and a reduced end portion forming a shoulder therebetween, a thrust body mounted upon the reduced end portions of the shafts, said thrust body having outwardly facing thrust surfaces in engagement with said shoulders and extending radially outwardly the-refrom, a rolling cutter on each of said shafts, each of said cutters having a bearing surface rotatable upon said cylindrical portion of the shaft and a thrust surface complemental to and engageable with the outwardly extending portion of the associated thrust surface on the thrust body.

2. in a reaming bit, a bit head, downwardly extending legs thereon, inwardly extending shafts on said legs, the inner end of each of said shafts terminating in a cylindrical portion and a reduced end portion forming a shoulder therebetween, a thrust body mounted upon the reduced end portions of the shafts, said thrust body having outwardly facing thrust surfaces in engagement with said shoulders and extending radially outwardly therefrom, a rolling cutter on each of said shafts, an antifriction bearing between the cutter and shaft outwardly from said cylindrical portion thereof, an inwardly extending flange on the inner end of said cutter rotatable about said cylindrical portion of the shaft and presenting a thrust surface complemental to and engageable with the associated thrust surface on the thrust body.

References Cited in the file of this patent UNITED STATES PATENTS 1,388,424 George Aug. 23, 1921 1,983,283 Garfield Dec. 4, 1934 1,983,316 'Scott et al. Dec. 4, 1934 2,058,628 Reed Oct. 27, 1936 2,068,375 Catland Jan. 19, 1937 2,086,682 Scott July 13, 1937 2,177,866 Catland Oct. 31, 1939 2,216,894 Stancliif Oct. 8, 1940 2,293,603 Francis Aug. 18, 1942 2,329,751 Fermier Sept. 21, 1943