US2381415A - Drill bit - Google Patents

Description

7, 5- E. B. WILLIAMS, JR

DRILL BIT Filed Nov. 19, 1943 INVENTOR: fdward 5 Mfi/lbmgJ:

A TTORNEYS.

Patented Aug. 7, 1945 "um'rap STATES PATENT OFFICE 2,381,415 palm. arr

Edward B. Williams, Jr., Greenville, Tex.

Application November 19, 1943, Serial No. 510.946

8 Claims.

This invention relates to drill bits, particularly of the type used in drilling earth formations, as disclosed in my application for patent,

provide a suitable starting surface without excessive pressure at the point of the bit; to provide a drill bit having a tapered drilling face transversed with channels or grooves between the cutting elements so as to provide movement of cuttings and drilling fluid across the face of the bit when the bit is in operation; and to provide the bit with watercourses cooperating with bit.

Fig. 4 is an enlarged section through the drilling face of the bit, particularly illustrating the cutting grooves intermediate the rows of cutting 2 elements.

Referring more in detail to the drawing: I designates a drill bit constructed in accordazice with the present invention and which is lar rock formations.

particularly adapted for drilling chert and simi- The bit includes a substantially cylindrical body 2 formed of material capable of withstanding strains and pressures incidental to drilling, and having shape to provide a substantially frusto-conical end 3 having a substantially flat central portion 4. The outer marginal edges-of the face 3 round into the cylindrical side face 5. of the bit body as indicated at 6, Fig. 2. Formed on the upper end of the body 2 is an externally threaded neck l for attachment of the bit to a drill pipe not shown. The body of the bit is provided with an axial bore 8 ex- 1 tending inwardly thereof from the neck I and of recesses ill for anchoring a matrix H.

which terminates short of the flattened area i to provide a wall thickness 9 therebetween.

The exterior of the side face portion 5 and the conical end face 3 are provided with a plurality The matrix ll is formed of relative hard and tough material such as bronze or a similar metal alloy or a plastic capable of being cast upon the body ofv the bit and having the property for retaining cutting elements such as diamonds l2 securely embedded therein. The matrix material is also selected so that it is capable of wearing to expose cutting points of the diamonds when the drill bit g is being used for drilling in chert or similar formations. The matrix is of a thickness to provide ample strength and depth to bed the cutting elements, and to accommodate a plurality of grooves or passageways I3 for movement of cuttings to primary and secondary water courses I and IS. The matrix extends upwardly and is shaped to provide a cylindrical face l6 and also serves to bedcutting elements H to provide a reaming face It for the drill bit.

The drilling face of the bit substantially conforms in shape to the end face of the body 2 in that it includes a central fiat area IQ of sumcient. size to provide a starting surface for the bit whencutting chert formations. The outer portion of the end face tapers in cone-like formation at a suitable angle, for example, substantially -l5, and joins with the reaming face l8 on a rounding curve 20.

In order to offset the excessive pressure acting at the center of the bit upon initial starting of a cutting operation, the central portion of the flat area 6 has an inwardly extending cone-like recess 2| so that when the drill bit is first placed in operation on the hole bottom only the flat area surrounding the recess begins to cut the formation. With. this arrangement,. the initial cutting area is limited so as to facilitate starting of the bit in chert and similar formations.

The cutting elements l2 bedded in the drilling face ofthe bit are shown arranged in spiral rows 22 at the side of the grooves l8 which provide for passage of the cuttings produced by the cutting elements. The cutting elements are preferably oriented within the matrix with their axes at substantially 15 relatively to the plane of the cutting face of the bit and with the points thereof extending in the rotational direction of the bit. The cutting elements I! are similarly bedded within the matrix to cover the reaming surface thereof;

however, the cuttings receiving grooves may be omitted in this section of the bit.

The primary watercourses H are formed in the matrix material and extend substantially radially from the axis of the drill bit to the periphery thereof and Join with upwardly extending watercourses 23 formed in the reaming face I8 and which terminate above the reaming face as indicated at 24 within a, bevelled periphery 25 of the matrix. v

The inner ends of the primary watercourses are connected with the bore 8 by ports 26, at least one of which connects with and discharges into the recess 2|. Certain of the watercourses also connect with the recess 2| as indicated at 21 to efiect discharge of material which is cut and broken off by the cutting elements 28 embedded within the surface of the recess as best shown in Fig. 2.

The secondary watercourses I! extend spirally from the primary watercourses, thus the drilling face is divided into a series of segments 29 having the rows of spirally arranged cutting elements and intermediate passageways I! with the sections traversed by the secondary courses. The innermost secondary passageways preferably connect the adjacent primary watercourses as indicated at 30, and the outermost secondary watercourses connect the primary watercourses at the periphery of the bit with upwardly extending secondary watercourses 3| as best shown .in Fig. l. The groove-like passage ways intermediate the rows of cutting elements are thus connected by the secondary and primary watercourses so that when the cuttings enter the grooves they move therealong to pass through the watercourses and are carried to the top of the wall by the drilling fluid.

In making the bit, a mold is formed of sand and suitable binder and is shaped to provide the drilling and reaming faces, the watercourses, and the cuttings receiving grooves. The cutting elements are then temporarily secured to the surface of the mold in the desired patterns, after which the bit body is inserted into the mold and the matrix material is poured therearound. The

matrix material flows in and around the cutting elements and into the recesses I0 for forming keys 32 to anchor the matrix from movement on the body member. 7

When the matrix material has set, the bit is removed from the mold and the cutting elements are rigidly embedded in the matrix material and the matrix material is securely anchored to the body. Since the mold is shaped to form the sector-shaped cutting faces, watercourses, and grooves, these portions ofthe bit are complete;

a but it is necessary to drill the water ports or channels 28 to connect with the bore 8.

when the bit is to be used, it is attached to the lower end of a drill pipe as in conventional practice and the assembly lowered to the bottom of the borehole. The drill pipe is then rotated by a conventional rotary drilling rignot shown. During rotation of the bit, the flat central drilling face starts the cut and as the operation progresses the cut extends to the periphery of the drilling face of the bit. Thus, by starting the cutting operation over a limitedarea, the cutting operation is facilitated and since the recess is provided at the center of the bit, the destructive effects of excessive pressure at this point is avoided. However, as the cutting area is extended the cutting elements within the face of the recess |8 become eflective to out the pointlike formation which extends thereinto. Should this formation break off the watercourses connected therein are of suflicient size to readily discharge the material under the propelling influence of the drilling fluid discharged through the port that is connected with the recess.

During the initial rotation, the matrix material wears sufflciently to expose the cutting elements to render them effective for cutting the formation, the cuttings of the formation being discharged into the passageways l3 and the cuttings are discharged therethrough into the watercourses for discharge into the borehole above the body of the bit. During rotation of the bit the cutting elements in the reaming surface of the bit will prevent any tendency for the bit to bind in the borehole.

From the foregoing it is obvious that I have provided a bit structure particularly adapted for drilling chert and similar formations.

What I claim and desire to secure by Letters Patent is:

l. A rotary drill bit including a body having a drilling face provided with spirally arranged cuttines receiving grooves, and cutting elements bedded in said face on respective sides of said grooves, said face havin'g watercourses dividing said face into sections and connecting sa d grooves, and said sections having secondary watercourses extending transversely of said grooves.

2. A rotary drill bit including a body provided with a substantially frusto conical drilling face and having a recess in the axis of said bit, said body having a substantially axial bore and having a port connecting the bore with said recess at a point offset from the rotational axis of the bit for passage of a drilling fluid, therethrough. the drilling face having a watercourse extending from the recess across said drilling face.

3. A rotary drill bit including a body provided with a substantially frusto conical drilling face and having a recess in the axis of said bit, said body having a substantially axial bore connected with said recess for passage of a drilling fluid to the drilling face, said drilling face having a watercourse extending from said recess to the periphery of the bit, and cutting elements bedded in said face including walls of said recess, said cutting elements in the drilling face being arranged in substantially spiral rows, the drilling face having grooves intermediate said rows of cutting elements and having connection with said watercourse.

4. A rotary drill bit including a body, a. matrix on said body having a drilling face and having a recess in the axis of said bit, said body having a substantially axial bore connected with said recess for passage of a drilling fluid, said drilling face having a watercourse extending from said recess to the periphery of the bit, and having cuttings receiving grooves connected with the watercourses, and cutting elements bedded in said matrix between said grooves.

5. A rotary drill bit including a body provided with a substantially frusto conical drilling face and having a recess in the axis of said bit, said body having a substantially axial bore connected with said recess for passage of a drillin fluid, said drilling face having a watercourse extending from said recess to the periphery of the bit, and having substantially spiral cuttings receiving grooves connected with the watercourse, and

cutting elements bedded in said face including arranged in substantially spiral rows between said grooves.

6. A rotary drill bit including a body provided with a substantially frusto conical drilling face and having a recess in the axis of said bit, said body having a substantially axial bore connected with said recess for passage of a drilling fluid, said drilling face having a watercourse extending from said recess to the periphery of the bit and cutting elements bedded in said face, said cutting elements being arranged in substantially spiral rows, the drilling face having cuttings receiving grooves intermediate said rows of cutting elements and having connection with said watercourse.

7. A rotary drill bit including a body, a matrix material keyed to said body for forming a drilling face provided with spaced spirally arranged

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