US2201379A - Drill bit - Google Patents

Description

J. F. sHAw 2,201,379

DRILL BIT Filed June 2, 1939 2 Sheets-Sheet 1 I, Qgfxr v J. F. SHAW May 21, 1940.

DRILL BIT Filed June 2, 1939 2 Sheets-Sheet 2 Patented May21 1940 PATENT OFFICE DRILL BI'I' John F. Shaw, Los Angeles, Calif.I assignor to Reed Roller Bit Company, Houston, 'lex., a

corporation of Texas Application June 2, 1939, Serial N0. 276,968 '1 Claims. (Cl. 255-571) This invention relates to drill bits, and has particular reference to bits of the roller type, wherein roller cutters are rotatablymounted on the bit head and are provided with-cutter teeth which dig into the formation as the cutters roll thereupon.

'The general object of this invention is to provide a novel and advantageous structure which may be more readily assembled and which will provide a more effective and durable drill than those in use heretofore. 1

In the type of drilling bit known as a cross roller bit there are customarily provided a pair of side cutters adapted to cut at the sides of the bottom of the hole and located in positions which are substantially diametrically opposite each other with respect to the bit head. Between these two cutters and extending. transversely with respect to a line drawn between them there is ordinarily a cross roller cutter pin on which are mounted a plurality of cross roller cutters adapted to cut the central portion of the bottom of the hole. These cross roller pins are normally disposed on a plane substantially at right angles to' the axis of rotation of the bit and when the bit is in vertical position the cutter pins and cross roller cutters mounted thereon will have their axes disposed substantially horizontally and in alignment with each other. v 9 In the usual type of bit just described the axial extent of the side cutters is limited by the presence between the side cutters of the cross roller cutters. Considerable difficulty has been experienced with the bearings of the side cutters be- 3 cause of this necessarily limited axial extent of the side cutters. Specifically, it has been proposed that the side cutters be provided with radial bearings of the friction type in a position spaced inwardly from the usual anti-friction bearings.

It is an object of this invention to provide a structure of the general type set forth in which there will be a greater'amount of room for .the side roller cutters and bearings therefor. More specifically, it is an object of this invention to provide a structure in which there will be a greater amount of room than in the usual construction for a friction bearing such as above described. 1 v

' In addition to the foregoing, it is an object of this invention to provide a structure in which the outer supports for the cross roller cutter pins will be stronger andmore durable than in previous constructions.

Another object of this invention is to provide a drill bit structure in which the cutters and their bearings and supporting means may be assembled and secured together as a unit, after which they may be handledas a unit and assembled with respect to the body of the drill. 5

In the drawings: Fig. 1 is a vertical cross section illustrating a bit constructed in accordance with this invention.

Fig. 2 is a partial vertical cross section taken 1 substantially at right angles to Fig. 1 and showing the structure of the side cutter mounting of the bit illustrated in Fig. 1.

Fig. 3 is a view showing the bit head before the cutter and bearing assembly has been se- 15 cured thereto.

Fig. 4 is a view showing the cutter and bearhing dassembly prior to mounting upon the bit Referring now more in detail to the drawings, 20 the numeral i designates the bit body and the numeral 2 the threaded shank thereof by which it is connected to the lower end of the drill stem. Extending downwardly from each of the four sides of this body member are arms, two of which 25 are designated by the numeral 3 and the other two by the numeral 4. Each of the arms 3 and 4 is provided with a flat outer surface and with an inclined shoulder at the upper end thereof for the purpose of receiving supporting arms to an be welded or otherwise secured thereto as will be presently described.

The cutter and bearing assembly which is i1- lustrated in side elevation in Fig. 4 consists of a pair of cross roller cutters 5 and 6 and a pair of side roller cutters I mounted upon suitable bearing supports adapted to be connected to the head I. The bearings for the cross roller cutters consist of cutter pins or shafts 8 and 9, respectively, the cutter pin 8.being formed in this 40 instance integral with an upstanding-arm Ill and the cutter pin 9-being formed with a similar arm ll. These pins are, of course, straight throughout their length and extend downwardly and inwardly as clearly illustrated in Fig. 1 and their inner ends are disposed in an opening'in a bridge member I! which extends transversely of the head and substantially at right angles to a line between the arms to and H. The ends of the shafts 8 and 9 may be welded together within the opening in the bridge as shown at i3, or they may be otherwise held in this opening by anysuitable means. The cross roller cutters 5 and 6 are of such length or extent as to traverse substantially'the entire area of the bottom of a hole within the pathof said side cutters.

The opposite ends of the bridge are provided with suitable spindles for the reception of the side cutters 7. These spindles have axes extending downwardly and inwardly withrespect to each other, and it will readily be observed that there will be a greater spaceavailable longitudinally of these axes by virtue of the fact that the cross cutter pins" extend downwardly and inwardly, than there would be if these cutter pins extended substantially horizontally, in the usual manner. It is, therefore, possible to make these spindles longer by virtue of the present construction.

The shaftsB and 9 which support the cutters 5 and 6, respectively, are each formed in the usual -manner with races for roller bearings it and 1-5 I adapted to take the radial load from these cutters respectively, and with a race for a ball hearing [6 adapted to take the outward end thrust I from these cutters;

The spindles for the side cutters l are each provided with a circumferential groove ll adapted to receive ball thrust bearings 68 and with a roller race IQ of reduced diameter to receive the roller bearings 20. The ball bearings l8 fit the groove 2| forming a raceway in the interior of the cutter l and 'are adapted when in place to take the end thrust of this cutter. The

outer ends of the spindles just described extend beyond the side cutter 1 and areadapted to be received within openings in the side supporting arms 22 which extend upwardly therefrom. These side supporting arms are adapted to be welded as at 23 to the outer ends of the spindles respectively. Each of the side supportin arms is also providedwith an opening adapted to receive ,a dowel pin 24 which in turn will register with an opening in one of the arms 3 of the bit head when the bearing assembly occupies the proper position with respect to the bit head.

By virtue of the'additional space made availis shown in the present example in the form of a friction bearing, the cutter being formed with a part 28 inwardly of the race 2| adapted to bear directly upon a friction bearing surface 29 formed on the spindle. This of course provides a more sturdy bearing structure for the side cutters and one better capable of taking the tremendous radial load imposed upon thesecutters in operation.

In addition to the above, the inclination of the cross roller cutter pins makes it possible to use arms I0 and H which are of greater cross section area above the point where the cutter pins are joined thereto than would be the case if these cutter pins were horizontal. That is, when the cutter pins are inclined as shown in Fig. 1, the arms [0 and II just above the outer ends of these cutter pins may be made with greater radial dimensions than if these pins were horizontal, without interfering with the action of the cutters.

This oi. course produces a much stronger and sturdier support for the cross cutter pins and a makes possible a more durable bit construction.

a to temporarily hold this assembly in place and these dowels welded in as shown at 25. The arms I0, I I and 22 may then be welded to the bit head as shown at 26 and 2-1 respectively, after which the bit is ready for operation.

It will readily be seen from the foregoing that a means has been provided whereby the cross roller cutters of a roller bit may be disposed so as to provide more room for the side cutters thereof and make possible a more satisfactory bearing for the side cutters. At the same time, there has been made possible a morerugged support structure for the cross roller cutters. In addition, a structure has been disclosed in which it is possible for the various cutter and bearing has thus been illustrated which is capable of accomplishing all of the objects and advantages sought by this invention.

Having described my invention, I claim:

1. In a roller bit, a pair of side cutters adapted to cut at the sides and bottom of a hole, a pair of cross-cutter bearing pins, each extending downwardly and inwardly toward the center. of the bit, and being straight throughout its entire length, and cross roller cutters mounted on said bearing pins, said cross roller cutters being of such extent as to traverse substantially the entire area of the bottom of a hole within the path of said side cutters. i

2. In a roller bit, a pair of side cutters adapted to cut at the sides and bottom of a hole and each havinga relatively long inwardly extending bearing portion, a pair of cross roller cutters extende ing transversely of the bit, a pair of substan-' tially straight shafts on which said roller cutters are mounted, said shafts extending inwardly and downwardly with respect to the axis of rotation of said bit to clear said relatively long bearing portions, said pair of roller cutters being of such length as to alone traverse substantially the entire area of the bottom of a hole within the path of said side cutters.

3. In a roller bit, a pair of side cutters adapted to cut at the sides and bottom of a hole and each having an anti-friction radial bearing adjacent its outer end, a thrust bearing intermediate its ends, and a frictionradial bearing adjacent its inner end, and a pair of cross roller cutters extending transversely of said bit and each ha ing an axis extending inwardly and downwardly with respect tothe axis of rotation of said bit to clear said friction radial bearings.

4. In a roller bit, .a pair of sidecutters adapted to cut at the sides and bottom of a hole and each having a relatively long inwardly extending bearing portion and a pair of cross roller cutters extending transversely of said bit and each having an axis extending inwardly and downwardly with respect to the axis of rotation of said bit to clear said relatively long bearing portions; and a bridge member bridging the space between said side cutters and extending between said cross roller cutters to form a support for the inner ends of said cross roller cutters.

5. In a roller bit, a pair of side cutters adapted to cut at the sides and bottom of a hole and each having an anti-friction radial bearing adjacent its outer end, a thrust bearing intermediate its ends, and a friction radial bearing adjacent its inner end, a pair of cross roller cutters extending transversely of said bit and each having an axis extending inwardly and downwardly with respect to the axis of rotation of said bit to clear said friction radial bearings, and a bridge extending between the inner ends of said side cutters and between said cross roller cutters and forming a support'for the inner ends of said cross roller cutters.

6. In a roller bit, a pair of side cutters adapted to cut at the sides and bottom of a hole, and a pair of cross roller cutters extending transversely of said bit and each having an'axis'extending inwardly and downwardly with respect to the axis of rotation of said bit, cross cutter bearing pins extending through said cross roller cutters, re-

a bithead spectively, and arms extending upwardly from the outer ends of said pins for supporting the same, said arms having their inner surfaces adjacent their lower ends extending upwardly and inwardly substantially at right angles to said cross cutter pins, whereby thecross section areas of said arms will increase upwardly.

7. In a cutter and bearing assembly for a roller bit, a bridge having downwardly and inwardly inclined spindles adjacent its opposite ends, side cutters rotatably mounted on said spin- .dles, cross cutter pins extending. upwardly and outwardly from the intermediate portions of said bridge; cross cutters rotatably mounted on said pins, and securing arms extending upwardly from the outer ends of said spindles and said cross cutter pins respectively for securing said assembly to JOE! 1". SHAW.

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