US3139946A

US3139946A - Replaceable drill bit structures

Info

Publication number: US3139946A
Application number: US208678A
Authority: US
Inventors: Charles L Bronson
Original assignee: Varel Manufacturing Co
Current assignee: Varel International Inc
Priority date: 1962-07-05
Filing date: 1962-07-05
Publication date: 1964-07-07
Anticipated expiration: 1981-07-07

Description

C. L. BRONSON July 7, 1964 INVENTOR. Char/es L. Bronson BY K ATTORNEY my] 7 July 7, 1964 c. 1.. BRONSON REPLACEABLE DRILL BIT STRUCTURES 8 Sheets-Sheet 2 INVENTOR. Char/es L. Bronson BY A 77'0R/VEY W July 7, 1964 3, BRQNSQN 3,139,946

REPLACEABLE DRILL BIT STRUCTURES Filed July 5, 1962 8 Sheets-Sheet 3 INVENTOR. Char/es L. Bronson ATTORNEY July 7, 1 c. L. BRONSON REPLACEABLE DRILL BIT STRUCTURES 8 SheetsSheet 4 Filed July 5, 1962 INVENTOR. Char/es L. Bronson.

ATTORNEY July 7, 1964 c, BRQNSON 3,139,946

REPLACEABLE DRILL BIT STRUCTURES Filed July 5, 1962 8 Sheets-Sheet 5 INVENTOR. Char/es L. Bronson y 7 5 c. L. BRONSON 3,139,946

REPLACEABLE DRILL BIT STRUCTURES Filed July 5, 1962 8 Sheets-Sheet 6 IIIVIIIIII A ATTORNEYS July 7, 1 c. L. BRONSON REPLACEABLE DRILL BIT STRUCTURES 8 Sheets-Sheet 7 Filed July 5, 1962 INVENTOR Charles L. Bronson ATTORNEYS July 7, 1964 c. 1.. BRONSON REPLACEABLE DRILL BIT STRUCTURES 8 Sheets-Sheet 8 Filed July 5, 1962 I 1 875 l l INVENTOR Charles L. Bronson F|G.28 BY ATTORNEYS United States Patent 3,139,946 REPLACEABLE DRILL BIT STRUCTURES Charles L. Bronson, Dallas, Tex., assignor to Varel Manufacturing Company, In'c., Dallas, Tex., a corporation of Texas Filed July 5, 1962, Ser. No. 208,678 24 Claims. (Cl. 175-412) This invention relates to new and useful improvements in well drilling bits, and more particularly, but not by way of limitation, to rotary drill bit structures having cutter elements which are adapted to be replaced upon damage or wear.

During the drilling of a well, the drill bit at the lower end of the drill string encounters a considerable amount of wear and damage from abrasion, and it is economically desirable to replace the worn cutter elements of the bit without replacement of the entire bit. As a result, many types of detachable cutter elements have been developed for facilitating the drilling operation; however, there are many problems to be solved that have not been completely overcome with the presently available replaceable bit structures. For example, it is desirable to maintain a simplicity of operation for the changing of the cutter elements and yet assure that the detachable bit will be securely retained in connection with the bit body, since any inadvertent loss of the cutter elements due to the work 7 load or conditions under which the bit is operating is extremely undesirable. In addition, a rotary type rock bit must gage to a particular bore hole size within fairly close limits, usually not exceeding a thirty-second of an inch. In order to provide these accurate drilling requirements, it is necessary to maintain positive location and alinement of the cutter elements with the axis of the bit body or holder structure. This has been a particular problem with detachable bit devices, and has not been adequately solved by the structures presently available.

The present invention contemplates novel drill bits having replaceable cutter elements particularly designed and constructed for simplicity of loading, or changing of the cutter elements. A plurality of wedge members are disposed in a circle at the lower end of a drill bit body to provide a plurality of circumferentially spaced, upwardlyconverging slots or ways of inverted V-shape therebetween for receiving the shanks of cutter elements which have upwardly-converging lateral surfaces or sides complementary to the configuration of the ways. The shanks are adapted to be inserted in the ways and confined therein by a retainer which is suitably connected to the body and surrounds said shanks whereby said shanks are wedged in said ways. Also, the sides of the wedge members and the cutter element shanks are tapered transversely to provide a compound taper whereby said shanks are forced radially outward into engagement with the retainer. In this manner, the alignment of the cutter elements may be held very accurately so that the drilling gage of the bit is well within the allowable limits. The novel replaceable drill bit structures are simple and efficient in both operation and construction.

It is an important object of this invention to provide novel replaceable drill bit structures wherein removable cutter elements are securely retained on a bit body for precluding accidental loss thereof during the drilling of a well.

Another object of this invention is to provide novel drill bit structures wherein the cutter elements thereof may be readily removed and replaced although positively held against displacement.

An object of this invention is to provide novel bit drill structures having replaceable cutter elements particularly 3,139,945 Patented July 7., 1964 designed and constructed for maintaining a substantially exact alinement between the cutter elements and the axis of a bit body.

Still another object of this invention is to provide novel drill bits having replaceable cutter elements wherein the drilling gage of the bits may be maintained within substantially exact limits.

A further object of this invention is to provide novel drill bits having replaceable cutter elements which are simple and efiicient in operation and economical and durable in construction.

Another object of the invention is to provide improved replaceable drill bit structures having wedge means for coacting with the shanks of cutter elements in such manner as to maintain said shanks in positive engagement with exterior confining means.

A further object of the invention is to provide improved drill bit structures, of the character described, wherein the wedge means and cutter element shanks have coacting wedge surfaces for forcing the shanks radially outward into tight engagement with a surrounding confining memher and maintaining said shanks against lateral displacement.

A particular object of the invention is to provide improved drill bit structures, of the character described, wherein the wedge means may be made integral with or formed separately of the body of the drill bit structure for detachable connection therewith, wherein said wedge means may have integral or separate wedge members and wherein said wedge means may have a thimble for coacting with said wedge members, such as by controlling the flow of air or other drilling fluid to the cutter elements or connecting said wedge members to one another.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention'will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, wherein examples of the invention are shown, and wherein:

FIG. 1 is a perspective view of a drill bit constructed in accordance with the invention;

FIG. 2 is a perspective elevational view of the drill bit partially assembled,

FIG. 3 is an exploded, perspective view of the drill bit in complete disassembly,

FIG. 4 is a broken, transverse, vertical, sectional view of the drill bit with portions thereof depleted in dotted lines for purposes of illustration,

FIG. 5 is a vertical, sectional view, taken on the line 55 of FIG. 6,

FIG. 6 is a horizontal, cross-sectional view, taken on the line 6-5 of FIG. 4, showing a four blade bit,

FIG. 7 is a horizontal, cross-sectional view, taken on the line 77 of FIG. 4,

FIG. 8 is a view, similar to FIG. 6, showing a three blade bit,

FIG. 9 is a perspective view of a two cone rotary bit embodying the invention,

FIG. 10 is an end elevational view of one of the replaceable cutter elements of the bit shown in FIG. 9,

FIG. 11 is a side elevational view of the replaceable cutter element,

FIG. 12 is a transverse, vertical, sectional view, taken on the line 1212 of FIG. 11,

FIG. 13 is a perspective view of a three cone rotary drill bit embodying the invention,

FIG. 14 is a perspective view of the bit shown in FIG. 13 partially disassembled,

FIG. 15 is a side elevational view of a rotary drill bit structure having four replaceable cutter elements,

FIG. 16 is an enlarged, top plan view, taken on the line 16-16 of FIG. 15,

FIG. 17 is a transverse, vertical, sectional view, taken on the line 17-17 of FIG. 16, showing one of the cutter elements in broken lines and a portion of a drill pipe,

FIG. 18 is a horizontal, cross-sectional view, taken on the line 1818 of FIG. 17,

FIG. 19 is a perspective view of the wedge and thimble assembly for coacting with the shanks of the cutter elements of FIGS. 15-18, the packing for the ports of the thimble being omitted,

FIG. 20 is a transverse, vertical, sectional view of a modified drill bit structure having three replaceable cutter elements,

FIG. 21 is a horizontal, cross-sectional view, taken on the line 21-21 of FIG. 20,

FIG. 22 is a perspective view of the wedge and thimble assembly for coacting with the cutter elements of the drill bit structure of FIGS. 20-21,

FIG. 23 is a view, similar to FIG. 20, of the lower portion of another modified drill bit structure,

FIG. 24 is a horizontal, cross-sectional view, taken on the line 24--24 of FIG. 23,

FIG. 25 is a view, similar to FIGS. 20 and 23, of the lower portion of a further drill bit structure modification.

FIG. 26 is a horizontal, cross-sectional view, taken on the line 2626 of FIG. 25,

FIG. 27 is a view, similar to FIG. 26 and taken on the line 2727 of FIG. 25,

FIG. 28 is a side elevational view of the wedge portion of the structure shown in FIGS. 25-27,

FIG. 29 is a view, similar to FIG. 25, of the lower portion of a further modified drill bit structure, and

FIG. 30 is a perspective view of the wedge assembly of the structure shown in FIG. 29.

This application is a continuation-in-part of my copending application, Serial No. 81,535, filed January 9, 1961, now abandoned.

In the drawings, particularly FIGS. 4 through 7, the numeral generally indicates a drill bit structure comprising a main body portion or tubular body 12 having a screwthreaded box portion 14 at the upper end thereof for connection with the lower end of the usual drill pipe (not shown). The major portion of the body 12 is reduced to provide a neck 16 which has a plurality of circumferentially spaced, break out lugs 18, shown only in FIGS. 4 and 7 for purposes of illustration. The lower end of the reduced neck 16 is threaded at 20 for receiving a cylindrical sleeve or member 22 thereon. The threads 20 are preferably of the acme type for facilitating the threading of the sleeve 22 onto the body 12, but is not in any manner limited thereto. It will be apparent in FIGS. 4 and 5, that the bore of the sleeve is at least as large as the base of the threads therein whereby said sleeve may be threaded upwardly on the neck 16 to a position providing access to the lower end of the body 12, for a purpose as will be hereinafter set forth.

An internal, annular groove 24- is formed in the reduced neck 16 and is spaced slightly above the threaded portion 20 for receiving a suitable seal ring 26, preferably of the O-ring type. The upper end of the sleeve 22 is provided with an internal, annular seat 28 to cooperate with the seal ring 26 for precluding leakage of fluid therebetween to protect the threaded engagement between the neck and sleeve. An external, annular groove 30 is provided on the body 12 below the threads 20 and is conterminous with an outwardly-extending circumferential flange 32 at the lower extremity of said body. An axial, cylindrical thimble or element 34 is disposed below the body and has an external, circumferential flange 36 at the upper end thereof complementary to the flange 32 for abutment therewith, as clearly shown in FIGS. 4 and 5, for a purpose as will be hereinafter set forth.

A plurality of wedge members 38 are disposed around the thimble 34 and may be of substantially arcuate configuration, but not limited thereto. Each wedge memher 38 has an undercut or recess 40 at the upper end of the inner surface thereof for receiving the abutted

flanges

32 and 36 therein. In this manner, the wedge members may be longitudinally positioned around the thimble 34. The lateral surfaces or

sides

42 and 44 of each wedge member are tapered or converge downwardly as best shown in FIG. 3. In addition, the tapered

sides

42 and 44 are provided with a transverse taper 46, particularly shown in FIG. 6, whereby said sides have a compound taper. When the Wedge members 38 are disposed around the thimble 34, the

sides

42 and 44 of adjacent wedge members 38 provide an inverted V-shaped or way 48 (FIG. 2) therebetween for receiving cutter elements or blade bits 50 therein.

The cutter elements 50 are replaceable or removably disposed within the ways 48 and each includes an upper shank or reduced portion 52 of substantially arcuate configuration for disposition around the thimble 34. As depicted in FIGS. 1 through 8, the cutter elements 50 have the usual outwardly and upwardly tapering or stepped cutting edges or members 54 which are commonly utilized in a drill bit, such as the type known as a drag bit. It is to be understood, however, that the invention is not limited to a bit of the drag bit type, but may incorporate substantially any type drill bit, as will be hereinafter set forth in detail. It is preferable to provide the cutting edges 54 with tungsten carbide inserts (not shown) which are brazed or otherwise securely fixed within machined recesses (not shown) provided at the outer extremity of each cutting edge 54. This is well known in the drill bit art, and provides a substantially hard cutting surface for prolonging the useful life of the bit and increasing the cutting efiiciency thereof.

Each shank 52 has upwardly-converging or tapered

sides

56 and 58 complementary to the configuration of the

sides

42 and 44 of a pair of adjacent wedges 38. The

sides

56 and 58 are further tapered at 60 (FIG. 6) to provide a compound taper for the shank that conforms to the compound taper configuration of the wedge members. The shank is provided with an outwardly-extending boss or button 62 and the sleeve 22 has a plurality of circumferentially spaced openings 64 for receiving the buttons upon the assembly of the bit apparatus 10, as will be hereinafter set forth, in order to securely retain the cutter elements 50 Within the ways 48, and to preclude relative longitudinal or rotational movement between said cutter elements and the bit body 12. An axial bore or passageway 66 extends through the body in communication with the bore 68 of the thimble 34 to provide a fluid passageway through the bit 10 to the cutter elements 50.

The tapered sides 56 and 58 of each shank 52 cooperate with the

side

42 and 44 of adjacent wedge member 38 to provide positive location and alinement of each cutter element 50 with respect to the axis of the body 12. The compound taper on the shank is straddled milled by holding and locating on the arcuate surface of said shank on which the button 62 is disposed. Thus, the arcuate exterior of the shank and the button thereon become the locating means for both the milling operation and the final holding of said shank in the complete assembly. This is important in that it provides the removable mounting with the versatility necessary for adaption to the rotary rock bit cutter structure shown in FIGS. 9-14, wherein the gage of the well bore must be held within substantially close limits, as well as utilization with the drag bit structure shown in FIGS. l-8. In addition, a replaceable core bit may be readily adapted for use with the type of assembly depicted herein, thereby permitting use of the holder assembly with substantially any type of drilling bit, as desired.

The bit structure shown in FIGS. 1-7 is of the four blade drag bit type wherein four wedge members 38 are disposed around the thimble 34 in cooperation with four cutter elements 50; however, as clearly shown in FIG. 8, three wedge members may be provided for cooperation with three cutter elements. The configuration of the 3 wedge members of the three cutter bit is substantially the same as the wedge members of the four cutter bit, with only the circumferential dimensions thereof varied for disposition around the thimble. Similarly, the cutter elements 50 of the three cutter bit are substantially the same as the cutter elements of the four cutter bit, with only a dimensional difference therebetween, as is well known in the usual three and four blades drag bits.

In order to assemble the bit from the individual elements thereof as shown in FIG. 3 to the unitary bit structure depicted in FIG. 1, the break out lugs 18 are welded, or the like, to the exterior of the body 12 for facilitating the removal of the drill bit from the drill pipe (not shown) as is well known. The seal ring 26 is then moved upwardly over the reduced neck 16 for disposition adjacent the lower end of the break out lugs. The sleeve 22 is then threadedly secured to the threaded portion 20 and threaded upwardly sufficiently for exposing or permitting access to the flange 32 at the lower end of the body. The flange 36 of the thimble 34 is placed in abutting relationship with the flange 32, and the wedge members 38 are disposed around said thimble in such a manner that said abutting flanges are engaged within the recesses 40 of said wedge members. As hereinbefore set forth, three of the Wedge members are utilized when assembling a three blade bit, whereas four of the said wedge members are used upon the assembly of a four blade bit.

With the wedge members 38 in position around the thimble 34, the bit will appear as shown in FIG. 2; however, it is to be noted that the sleeve 22 is shown removed from the assembly for purposes of illustration. In the actual assembly, the sleeve is positioned on the reduced neck 16 above the wedge members and said wedge members are held in position around the thimble in any suitable manner (not shown) for encompassing said thimble. Then, the sleeve 22 is threaded downwardly on the neck 16 sufliciently for positioning the lower end of said sleeve beyond the lower extremity of the wedge members 38 approximately one to one and one-half inches. In this lower position of the sleeve, the groove 24 is exposed and the seal ring 26 may be moved downwardly over the neck for disposition within the O-ring groove 24. This portion of the structure so assembled may be referred to as the holder assembly and is now in condition for receiving the cutter elements 50.

In this lowered position of the sleeve 22, the openings 64 are disposed in proximity to the ways 48. The sleeve may be rotated on the threaded portion 20 for properly orientating the openings with respect to the ways for receiving the buttons 62 of the cutter elements 50, the shanks 52 of said elements being inserted in the annulus or annular space between said sleeve and the thimble 34 with each shank disposed in one of said ways. The shanks are inserted sufiiciently within the ways 48 to engage the buttons with the respective openings 64 of the sleeve 22. When all of the shanks 52 have been inserted properly within the respective ways, the sleeve is threaded upwardly on the body 12, or the reduced neck 16 thereof, whereby the engagement between the openings and buttons pulls the cutter elements 50 upwardly with respect to said body. The double or compound taper of each shank 52 tightly wedges with the double or compound taper of the wedge members 38 whereby the shank is forced radially outward against the bore of the sleeve 22.

With the cutter elements 50 thus securely locked in place on the bit body, the drill bit 10 is ready for use. The body 12 may be threadedly engaged at 14 with the lower end of the drill pipe (not shown) and rotated therewith, as is well known, for the drilling of a well bore (not shown). As hereinbefore set forth, the tapered sides of the shanks 52 cooperate with the complementary sides of the ways 48 to positively locate and aline the cutter elements with the longitudinal axis of the body and assure eificient drilling of the well bore.

In order to remove the cutter elements 50 from the remaining portions of the assembly, or the holder assembly, for replacement or the like, it is merely necessary to position said elements in the usual break out box (not shown) and rotate the main body 12 in the opposite direction from that of the drilling operation. Alternately, the main body may be held with the usual break out tongs (not shown) and the break out box in the rotary table may be rotated in an opposite direction to that of the drilling. This rotation may be continued until the sleeve 22 is lowered with respect to the body whereby the cutter elements are sufficiently disengaged from said sleeve to loosen said elements for easy removal thereof.

It will be apparent that the replaceable bit structure disclosed herein provides that only one bit shank or a number of bit shanks may be held in the assembly. The invention is not limited to any particular number of bit shanks, and substantially any number thereof may be provided. The determining factor as to the number of shanks to be held or retained by this structure is the number of slots or ways provided by the Wedge members 38. This feature is of particular importance when in use with drill bits of relatively large diameter. As a practical matter, it has been found that wedging or binding engagement of the wedge members 38 and shanks 52 against the sleeve 22 may be obtained if the

sides

42, 44, 56 and 58 thereof are provided with the correct transverse angularity. Thus, if desired, the thimble 34 may be omitted. Although the wedge members 38 are substantially segments of a cylinder in order to facilitate disposition of said members around the groove 30 of the body 12, it is anticipated that a circular wedge structure may be secured to the end of said body in some other manner than the abutting

flanges

32 and 36 engaging the groove 40 of the wedge segments. Thus, the circular wedge may be a unitary structure in lieu of a plurality of wedge segments.

Referring now to FIGS. 9-14, the replaceable bit structure is shown as being of the rotary cone type bit generally indicated at 70, and comprises the main body 12 having the reduced neck portion 16 of the first embodiment. The sleeve 22 cooperates with the body 12 and the wedge members 38 in the same manner as hereinbefore set forth. In the rotary bit structure 70, however, each cutter element 72 comprises an upwardly-extending shank 74 and an inwardly-directed, angularly-disposed spindle portion 76 of the Well known configuration of rotary cone bit holders for supporting the usual bearing members (not shown) which in turn carry cutter cones 78. It is preferable to provide a transversely-extending bore 30 in the spindle 76 for permitting the insertion of ball bearings (not shown) which are fed into the ball race (not shown) which is normally provided with the rotary cutters. A ball retaining pin (not shown) may be inserted and welded, or the like, within the bore 80 after insertion of the ball bearings for securing the balls in the raceway.

Each shank 74 is provided with an outwardly-directed boss or button 82 oppositely disposed from the spindle 76 and similar to the buttons 62 of the cutter element shanks 52. The shank 74 has upwardly-converging or tapered sides 84 and 86 (FIG. 11) which are transversely tapered as shown at 88 in FIG. 10 to provide a double or compound taper for cooperating with the wedge members 38 in the same manner as set forth hereinbefore.

In order to assemble the rotary type bit 70, the seal ring 26 is disposed around the body 12 and moved upwardly on the neck 16, and the sleeve 22 is threaded upwardly on said neck sufficiently for exposing or providing access to the lower end of said body. The thimble 34 is disposed adjacent the lower end of the body whereby the flange 36 is in abutment with the flange 32, and the wedge members 38 are disposed around said thimble with the grooves 40 thereon engaging said abutting flanges.

The sleeve 22 may then be threaded downwardly on the body 12 sufliciently for positioning the lower end of said sleeve beyond the lower extremity of the wedge members 38 approximately one to one and one-half inches, or to substantially the position shown in FIG. 14. The seal ring 26 may be moved downwardly on the neck 16 for disposition Within the complementary groove 24 therefor. This portion of the bit may be called the holder assembly and is now in condition for receiving the cutter elements 72. The shanks 74 of the cutter elements are disposed in the ways 48 provided between the adjacent wedge members and inserted upwardly between the sleeve 22 and thimble 34 until the buttons 82 engage the openings 64 of said sleeve. With the buttons disposed in the openings, the sleeve may be threaded upwardly on the neck 16 whereby the cutter elements 72 are moved upwardly for wedging the shanks tightly in the ways. The complementary compound tapers of the sides of the shanks 74 and wedge members 39 force said shanks and members radially outward into a tight engagement with the bore of the sleeve 22 as hereinbefore set forth. The rotary drill bit assembly 70 may then be threadedly secured to the lower end of the drill stem (not shown) and the drilling operation may be continued in the usual manner.

In order to remove the cutter elements 72 for replacement, or the like, the cutter cones 78 may be disposed in the usual break out box (not shown) and the main body 12 may be rotated in the opposite direction from that of the drilling operation. The sleeve 22 is backed off the neck 16 and the shanks 74 are loosened from wedging engagement with said sleeve to permit removal of the cutter elements.

The rotary bit 70 shown in FIG. 9 is of the two cone type whereas the assembly depicted in FIGS. 13 and 14 is of the three cone type. As has been stated, it is only necessary to alter the circumferential dimensions of the basic structures of the wedge members and shanks, depending upon whether or not a two cone or three cone bit is to be provided, or any other number of cones or cutters as described. The positioning of the shanks 74 on the body 12 by means of the cooperating tapered sides of the wedge members and shanks provides positive positioning of the cutter elements 72 in substantially exact alinement with the longitudinal axis of the body 12. In this manner, the bit Will efliciently drill the well bore in such a manner as to hold the gage of the bore within the substantially close limits that are required in this type of bit.

In FIGS. 15-19, the tubular body 110 of another drill bit structure embodying the principles of the invention is shown and has a screwthreaded box or socket 111 (FIG. 17) at its upper end for connection with the lower end of the usual drill pipe 112. External coarse screwthreads 113 are formed on the lower portion of the body 110, which is reduced in diameter, for engagement by the complementary internal screwthreads 114 of a cylindrical sleeve or elongated collar-like member 115. An O-ring or other seal means 116 may be interposed between the body and the upper end of the sleeve 115 for sealing off therebetween. As shown by the numeral 117, the lower portion of the bore of the sleeve is of a diameter sufficient to accommodate a wedge and thimble assembly 118 which is of substantially the same diameter as the reduced, screwthreaded lower portion of the body 110 and which is adapted to abut the lower end thereof and function as a continuation of said body.

The wedge and thimble assembly is best shown in FIGS. 17 and 19 and include a central cylindrical thimble portion or element 119 and a plurality of external wedge portions or members 120 for coacting with the shanks 121 of a plurality of replaceable cutter elements 122. An axial bore 123 extends through the thimble 119 and has an annular, upwardly-facing shoulder 124 at its lower end to removably support an orifice member 125 whereby the effective diameter of the bore may be varied in accordance with the available and/or desirable flow of air or other drilling fluid. In fact, if desired, the member 125 may be solid to prevent the flow of fluid through the thimble. The bore 123 is of less or of not greater diameter than the bore of the body to permit insertion and removal of the orifice member therethrough. It is noted that the cutter elements 122 may be of the blade or cone type, the latter being illustrated, and may vary in number, four elements being shown in FIGS. 15-19. When the cutter elements have rotatable cones, fluid courses 126 are usually formed therein to lubricate and/ or cool the spindles and bearings (not shown) upon which the cones are mounted. Lateral ports 127 are provided in the thimble 119 for directing the drilling fluid to the courses 126 when said courses are formed in the cutter elements 122. Preferably, as shown by the numeral 128, the lower end portion of the thimble is upset or enlarged to provide an external, annular shoulder for engaging internal complementary shoulders 129 at the lower ends of the wedge members 120 whereby said thimble depends below said members.

The shoulders 129 are formed by counterboring or internally recessing the lower end portions of the wedge members which are arcuate in cross-section and disposed around the thimble, said members being of greater length than and extending above said thimble. An axial bore 130, of substantially the same diameter as the bore 123 of the thimble 19, is formed within the upper portions of the wedge members 120 (FIG. 17) which are integral or otherwise joined due to the upward circumferential convergence of said members. As shown by the numeral 131, the thimble is welded to the members so that the assembly 118 is unitary in eifect. Each member 120 has inclined, transverse sides or surfaces 132 which converge downwardly whereby the adjacent sides or surfaces of the members are divergent downwardly to provide inverted V-shaped channels, slots or ways 133 between said members (FIG. 19). Also, the wedge surfaces 132 of each member extend at angles to each other in a transverse plane whereby said surfaces have a compound taper and, as best shown in FIG. 18, this angular relationship is 90 or less when four wedge members are employed. Thus, the Wedge surfaces are disposed in planes which intersect at an angle of approximately 90.

When only three wedge members are provided for coacting with the shanks of three cutter elements, the angular relationship of the surfaces 132 may be increased so long as it is 120 or less in order to exert an outward radial thrust on said shanks. Fewer ways permit greater angularity and more Ways require less angular relationship in order to force the shanks radially outward; for example, the angularity may be 180 or less for two ways, 72 or less for five ways, and 60 or less for six ways.

An external recess 134 is provided at the upper end portion of the wedge assembly by reducing the diameter thereof to permit downward movement of the sleeve relative to said assembly upon unthreading of said sleeve from the body 110. An inclined fluid course 135 may extend longitudinally through each member from the upper portion of the bore to the lower end of the member for directing air or other drilling fluid between and outwardly of the exteriors of the cutter elements so as to impinge upon the gage surface of the bore hole bottom (not shown). Obviously, the diameters of the fluid courses may be varied in accordance with the volume of drilling fluid available so as to provide a jet action which increases the penetration rate of the drill bit structure and prolongs the life of the cutter elements. Preferably, synthetic rubber or other suitable packing material 136 surrounds the ports 127 of the thimble 119 for engaging the shanks 121 of the cutter elements so as to seal off around said ports as well as the fluid courses 126 of said shanks, FIG. 17.

As shown in FIG. 18, the shanks of the cutter elements 122 are arcuate in cross-section and substantially complementary to the ways 133, in that, said shanks have longitudinally inclined and transversely tapered sides or surfaces 137 for parallel engagement with the inclined and tapered surfaces 132 of the wedge members 126. As a result, the shanks 121 have a snug, sliding fit in the ways and are urged radially outward by the coaction of the wedge surfaces 132 and 137 into engagement with the bore 117 of the sleeve 115 when the drill bit structure is assembled. A circular boss or button 138 projects radially outward from the upper end portion of each shank for engaging in a complementary opening 139 in the sleeve to secure the shank in one of the ways 133. The openings 139 are spaced circumferentially of the sleeve 115, with one opening being provided for each boss 138, and coact with the bosses to prevent displacement of the cutter elements 122.

The drill bit structure is readily assembled by partially threading the sleeve 115 onto the lower end of the body 110 and inserting the wedge and thimble assembly 118 in the bore 117 of said sleeve with the upper end of said assembly in engagement with the lower end of said body. Due to the external recess 134, the upper end portion of the assembly may be disposed within the lower end portion of the screwthreads 114 of the sleeve so as to dispose the openings 139 of said sleeve closer to the lower ends of the ways 133 of said assembly. Since the ways increase in size downwardly, clearance is provided for the reception of the shanks 121 of the cutter elements 122 and the engagement of the bosses 138 of said shanks in the openings 139 of the sleeve. Upon threading of the sleeve 115 upwardly relative to the body 110, the cutter element shanks slide upwardly in the ways 133 and are forced outwardly into tight engagement with the bore 117 of said sleeve due to the coaction of the wedge surfaces 132 and 137 of the wedge members of portions 120 and said shanks, respectively. Thus, the cutter elements are securely locked in position and the drill bit structure is ready for use. It is noted that each cutter element is mounted separately and that its attachment is not dependent upon the other elements, whereby one or more of said elements may be omitted. Manifestly, the cutter elements 122 are readily removable for repair or replacement by partial unthreading of the sleeve 115 from the body 110 so as to permit downward movement of the shanks 121 of said elements relative to the ways 133 of the assembly 118.

Attention is directed to the fact that the thimble 119 merely assists in controlling the circulation of the air or other drilling fluid and plays no part in supporting the cutter elements; however, a thimble could be utilized to connect the wedge members or portions of a wedge assembly, particularly, in drill bit structures of relatively small diameter in which it is not feasible to make the wedge assemblies integral or unitary. An example of such construction is shown in FIGS. 20-22, wherein the tubular body 140 of a drill bit structure has an axial externallyscrewthreaded pin 141 at its lower end for connection with a member or sleeve 142, similar to the sleeve 115 and having similar internal screwthreads 143 at its upper portion and a similar bore 144 at its lower portion for receiving a wedge assembly 145 which is somewhat similar to the assembly 118. Seal means 146, similar to the seal means 116, is disposed between the upper ends of the pin 141 and sleeve 142 and circumferentially spaced openings 147, similar to the openings 139 of the sleeve 115, are formed in the lower portion of the sleeve 142 for receiving the bosses 148 of the cutter element shanks 149. The cutter elements are not illustrated in detail since the same may be of any suitable type; however, it is noted that the wedge assembly 145 is adapted to accommodate three cutter elements rather than four although the number is immaterial.

The Wedge assembly includes a plurality or trio of independent wedge portions or members 150 disposed around a central, cylindrical thimble portion or element 151 which is similar to the thimble 119 but which is positioned Within the upper portions of the wedge members.

As shown by the numeral 152 in FIG. 20, the upper extremity of the thimble 151 may project above the wedge members 150 for engagement in an annular recess in the lower extremity of the bore of the tubular pin 141 of the body when the upper ends of said members engage the bottom of said pin. The recess of the pin bore may be counterbored to receive the O-ring or other seal means 153 for sealing off around the upper end of the thimble. A rivet or other fastener 154 loosely connects the upper end portion of each wedge member to the intermediate portion of the thimble 151 whereby the wedge members are suspended from said thimble. With the exception of circumferential width and integralness, the wedge members are identical to the wedge members 120 and have similar externally recessed or reduced upper end portions 155 to permit downward movement of the sleeve 142 relative to the assembly 145 and provide clearance for the insertion of the cutter element shanks 149 in the lower end of said sleeve and the engagement of the bosses 148 in the openings 147.

In addition, the wedge members 150 are provided with similar lateral sides or surfaces 156 which have similar compound tapers and which coact to provide similar inverted V-shaped slots or ways 157 between said members for the reception of the shanks 149. Although not shown, the cutter element shanks have lateral sides or surfaces complementary to the lateral surfaces 156 of the wedge members for parallel engagement therewith whereby said shanks have a snug, sliding fit in the Ways 157. Due to the coaction of these wedge surfaces, the shanks are forced outwardly into tight engagement with the bore 144 of the sleeve 142 in spaced relation to the thimble 151 (FIG. 20). It is noted that the angular relationship of adjacent wedge surfaces 156 is 120 or less and approximately 90 since three ways are provided.

As shown by the numeral 160 in FIGS. 23 and 24, the wedge members or portions may be made integral with the lower end of the tubular body 161 of a drill bit structure and have an axial bore 162 communicating with the bore of said body. In contour, the wedge portions are substantially identical to the wedge members 150 of the assembly 145 and have identical wedge surfaces 163 which coact to provide identical slots or Ways 164. The complementary cutter element shanks 149 are adapted to be confined in the ways 164 and forced radially outward into tight engagement with the bore of a surrounding member or sleeve 165. Instead of the sleeve being screwthreaded on the body 161, the wedge portions 160 are of reduced external diameter to provide a recess 166 for accommodating said sleeve which is secured to said wedge portions by screws or other suitable fasteners 167. Circumferentially spaced openings 168, similar to the

openings

139 and 147, are formed in the sleeve to receive the bosses or buttons 148 of the cutter element shanks 149.

In FIGS. 25-28, another drill bit structure is shown and includes a tubular body 170 which is similar to the body 140 and which has similar external screwthreads 171 at its lower portion. Wedge members or portions 172, identical to the wedge portions 160, are made integral with and depend from the body 170 and have identical wedge surfaces 173 and slots or ways 174 for engagement by and coaction with the cutter element shanks 149. A cylin drical member or sleeve 175, having internal screw threads 176 at its upper portion for connection with the screw-threads 171, is provided for surrounding and confining the shanks 149. Below the screwthreads 176, the bore of the sleeve is provided with an annular groove or recess 177 for receiving'and confining the bosses or buttons 148 of the cutter element shanks in the same manner as the

openings

139, 147 and 168.

A further modified drill bit structure constructed in accordance with the invention is shown in FIGS. 29 and 30 and includes a tubular body 180 having an elongated enlarged box or socket 181. The upper portion of the 3 box 181 has internal, left-hand screwthreads 182 for engagement by the complementary screw threads 183 of the reduced, upstanding pin 184 of a Wedge assembly 185. An O-ring or other seal means 186 is recessed in the bore 187 of the body 181) for surrounding and sealing off around the pin 184 which extends into said bore. As shown by the numeral 188, the lower portion of the box 181 is counterbored for surrounding the depending wedge portions 189 of the assembly 185 and the cutter element shanks 149 in the same manner as the sleeve 175. An annular groove or recess 190, similar to the groove 177, is formed in the upper portion of the counterbore 188, for receiving and confining the bosses or buttons 148 of the shanks.

The wedge portions 189 are substantially identical to the

wedge portions

161 and 172 and have identical wedge surfaces 191 and slots or ways 192 for engagement by and coaction with the cutter element shanks 149. In order to permit insertion of the cutter element shanks 149 and engagement of the bosses 148 in the groove 191), the screwthreaded portion 182 of the box 181 is of greater length than the screwthreaded portion 183 of the pin 184 and the counterbore 188 is of greater length than the wedge portions 189 of the assembly 185 to permit relative upward movement of said assembly suflicient to provide clearance for said cutter element shanks 149 and bosses 148. After which, the assembly is threaded downwardly in the box to force the shanks radially outward into tight engagement with the counterbore of said box whereby the lower portions of said box functions as a retainer or confining sleeve 193. Due to the left-

hand screwthreads

182 and 183, the wedging engagement of the assembly is tightened upon conventional rotation of the drill pipe. It is noted that the groove 1% as well as the groove 177 are provided to permit relative rotation after insertion of the cutter element shanks.

Due to the replaceability of the cutter elements, the structures make for economy since one or more of said elements may be replaced without the necessity of removing and replacing the entire bit structure. It is contemplated that the drill bit structures shown in FIGS. 9-14 and 23-30 could be provided with flow control means similar to the thimble 119 of the assembly 118 of FIGS. 15-19. Also, it is obvious that the circumferentially spaced

openings

64, 139, 147 and 168 of the sleeves 22,

115, 142 and 165 are the equivalent of the annular grooves 177 and 191) of the

sleeves

175 and 193 so as to be interchangeable therewith.

Attention is directed to the fact that the

wedge members

118, 160, 172 and 188 are spaced from the bores of their respective surrounding

sleeves

115, 165, 175 and 181; such spacing is shown by the numeral 117 in FIGS. 17 and 18 and by the numeral 166 in FIGS. 23 and 24, being shown but being unnumbered in FIGS. 25-27 and 29. This space permits slight deforming of the sleeves suflicient to absorb shocks resulting from the impact of the teeth of the cutter elements with the formation. Due to this flexibility or flexing of the sleeves, the durability of the cutter is increased, particularly, the bearings and teeth thereof. Since the wedge members 1511 are loosely mounted on the thimble 151 of the wedge assembly 145 and the bore 144 of the sleeve 142 is of greater diameter, said wedge members as well as the shanks 149 are capable of undergoing sufiicient radial movement to permit deformation of said sleeve for absorbing drilling shocks. Although not shown, the sleeve 22 could flex in a similar manner.

From the foregoing, it is readily apparent that the present invention provides novel replaceable drill bit structures wherein the cutter elements thereof may be quickly and efliciently removed for repair or replacement by cutter elements of similar or different type. The cutter elements are positioned on the main body portion in such a manner that said cutter elements are in substantial alinement with the longitudinal axis of the body thereby greatly 12 improving the drilling operation of the bit. The novel drill bit structures are simple and efficient in operation and economical and durable in construction.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

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

1. A replaceable drill bit structure including a body, wedge means at the lower end of the body and having a plurality of circumferentially spaced ways, each way having downwardly diverging sides, cutter elements having shanks complementary to and removably mounted in the ways, means cooperating between the cutter element shanks and the body for wedging said shanks in said ways and simultaneously positioning said cutter elements in substantial alignment with the longitudinal axis of said body, and the sides of said ways being tapered transversely inward of the wedge means and the shanks of the cutter elements have surfaces complementary to said sides.

2. A replaceable drill bit structure including a body, wedge means at the lower end of the body and having a plurality of circumferentially spaced ways, each way having downwardly diverging sides, cutter elements having shanks complementary to and removably mounted in the ways, means cooperating between the cutter element shanks and the body for wedging said shanks in said ways and simultaneously positioning said cutter elements in substantial alignment with the longitudinal axis of said body, said cooperating means including a sleeve-like member made integral with the body and encircling the wedge means and the shanks of the cutter elements and wedgedly engaged by said shanks, and said wedge means being detachably connected to said body.

3. A replaceable drill bit structure including a body, wedge means at the lower end of the body and having a plurality of circumferentially spaced ways, each way having downwardly diverging sides, cutter elements having shanks complementary to and removably mounted in the ways, means cooperating between the cutter element shanks and the body for wedging said shanks in said ways and simultaneously positioning said cutter elements in substantial alignment with the longitudinal axis of said body, said wedge means having fluid courses for directing fluid between and outwardly of the exteriors of the cutter elements and ports, said cutter elements having fluid courses communicating with the interiors thereof with the ports.

4. A replaceable drill bit structure as set forth in claim 3 wherein the wedge means includes an axial tubular element having the ports therein and a member in said element below the ports for controlling the area of said element.

5. A replaceable drill bit structure including a body, wedge means at the lower end of the body and having a plurality of circumferentially spaced Ways, each way having downwardly diverging sides, cutter elements having shanks complementary to and removably mounted in the ways, means cooperating between the cutter element shanks and the body for wedging said shanks in said ways and simultaneously positioning said cutter elements in substantial alignment with the longitudinal axis of said body, and said wedge means being integral with and depending from the body.

6. A replaceable drill bit structure as set forth in claim 5 wherein the cooperating means includes a member detachably connected to the body and extending around the wedge means and the shanks of the cutter elements and wedgedly engaged by said shanks.

7. A replaceable drill bit structure as set forth in claim 6 wherein the member has screwthreaded connection with the body.

8. A replaceable drill bit structure as set forth in claim 6 including an external projection on the shank of each cutter element, the member having means for receiving the projections of the shanks to connect the cutter elements to said member.

9. A replaceable drill bit structure as set forth in claim 6 including an external projection on the shank of each cutter element, the member having annular recess for receiving the projections of the shanks to connect the cutter elements to said member.

10. A replaceable drill bit structure including a body, wedge means at the lower end of the body and having a plurality of circumferentially spaced ways, each Way having downwardly diverging sides, cutter elements having shanks complementary to and removably mounted in the ways, means cooperating between the cutter element shanks and the body for wedging said shanks in said ways and simultaneously positioning said cutter elements in substantial alignment with the longitudinal axis of said body, and said wedge means including a plurality of members which are arcuate in cross-section.

11. A replaceable drill bit structure as set forth in claim 10 wherein the wedge members are detachably connected to the body.

12. A replaceable drill bit structure as set forth in claim 10 wherein the sides of the ways are tapered transversely inward of the wedge members and the shanks of the cutter elements have surfaces complementary to said sides.

13. A replaceable drill bit structure as set forth in claim 10 including a cylindrical thimble disposed within and having connection with the wedge members.

14. A replaceable drill bit structure as set forth in claim 13 including means loosely connecting the wedge members to the thimble.

15. A replaceable drill bit structure as set forth in claim 10 wherein the wedge members are made integral with each other and separate from the body, and means detachably connected to said body for securing said wedge members thereto.

16. A replaceable drill bit structure as set forth in claim 15 wherein the detachable connecting means includes a portion of the cooperating means.

17. A replaceable drill bit structure as set forth in claim 15 wherein the detachable connecting means is made integral with the wedge members.

18. A replaceable drill bit structure as set forth in claim 10 wherein the cooperating means includes a member detachably connected to the body and extending around the wedge members and the shanks of the cutter elements and wedgedly engaged by said shanks.

19. A replaceable drill bit structure as set forth in claim 18 wherein the member has screwthreaded connection with the body.

20. A replaceable drill bit structure as set forth in claim 18 including an external projection on the shank of each cutter element, the member having means for receiving the projections of the shanks to connect the cutter elements to said member.

21. A replaceable drill bit structure as set forth in claim 18 including an external projection on the shank of each cutter element, the member having openings for receiving the projections of the shanks to connect the cutter elements to said member.

22. In a replaceable drill bit, a main body member, a compression sleeve disposed in tandem relation with the main body member, a plurality of wedge segments disposed around the compression sleeve and carried by the main body member, each of said wedge segments provided with double tapered side edges, said side edges providing a plurality of circumferentially spaced V-slots around the outer periphery of the compression sleeve, a plurality of detachable cutter elements, each of said cutter elements having a shank member provided with double tapered side edges complementary to the side edges of the 14 wedge segments for disposition within the V-slots, and means cooperating between the cutter elements and the main body for wedging the shanks in the V-slots and simultaneously positioning said cutter elements in substantial alignment with the longitudinal axis of the main body member.

23. In a replaceable drill bit, a main body member having a threaded portion at one end thereof, an outwardly extending circumferential flange provided at the said end of the main body member, a compression thimble disposed in tandem relation with the body member, an outwardly directed flange provided on the compression thimble and in abutting relation with the first flange, a plurality of substantially cylindrical wedge segments disposed around the compression thimble, each of said wedge segments provided with a groove on the inner surface thereof for engaging the abutting flanges, double tapered side edges provided for each wedge segment, said double tapered side edges of adjacent wedge segments providing V-slots around the periphery of the compression thimble, a plurality of detachable cutter elements, a shank member provided on each cutter element and having double tapered side edges complementary to the side edges of the wedge segments for disposition in the V-slots, a sleeve threadedly secured to the main body member and extending over the wedge segments and a portion of the shank members, and means cooperating between the sleeve and the cutter elements for wedging the shank members in the V-slots and simultaneously positioning the cutter elements in substantial alignment with the longitudinal axis of the main body member.

24. In a replaceable drill bit, a main body member having a threaded portion at one end thereof, an outwardly extending circumferential flange provided at the said end of the main body member, a compression thimble disposed in tandem relation with the body member, an outwardly directed flange provided on the compression thimble and in abutting relation with the first flange, a plurality of substantially cylindrical wedge segments provided with a groove on the inner surface thereof for engaging the abutting flanges, double tapered side edges provided for each Wedge segment, said double tapered side edges of adjacent wedge segments providing V-slots around the periphery of the compression thimble, a plurality of detachable cutter elements, a shank member integral with each cutter element, said shank members having double tapered side edges complementary to the side edges of the wedge segments for disposition in the V-slots, an outwardly extending boss provided on each shank member, a sleeve threadedly secured to the main body member and extending over the wedge segments and a portion of the shank members, said sleeve provided with a plurality of circumferentially spaced apertures for engaging the boss of the shank members, said boss and apertures cooperating upon the threading of the sleeve in one direction for wedging the shanks in the V-slots and simultaneously positioning the cutter elements in substantial longitudinal alignment with the longitudinal axis of the main body member.

References Cited in the file of this patent UNITED STATES PATENTS 2,783,973 Hawthorne et al Mar. 5, 1957 2,978,049 Skidmore et al. Apr. 4, 1961 3,003,570 Roland Oct. 10, 1961 3,040,825 Williams June 26, 1962 3,075,594 Creel Ian. 29, 1963 FOREIGN PATENTS 57,346 France Jan. 2, 1953 OTHER REFERENCES Petroleum Engineering, December 1961, pp. 86-87.