Patent Publication Number: US-2020300086-A1

Title: Bit

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority to U.S. Provisional Application No. 62/864,241, filed Jun. 20, 2019, claims priority to and is a continuation-in-part of U.S. Provisional Application No. 62/476,194, filed Mar. 24, 2017, claims priority to and is a continuation-in-part of U.S. Non-provisional application Ser. No. 15/927,795, filed Mar. 21, 2018, and claims priority to and is a continuation-in-part of U.S. Non-provisional application Ser. No. 15/960,749, filed Apr. 24, 2018, to the extent allowed by law and the contents of which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This disclosure relates generally to a bit with a friction welded bit body used in mining, trenching, and milling equipment, a unitary bit used in mining, trenching, and milling equipment, and/or the use of a 4340 steel member of a bit and a nickel bearing braze alloy to attach a tungsten carbide insert to the 4340 steel member. 
     BACKGROUND 
     Road mining, trenching, and milling equipment utilizes bits and/or picks traditionally set in a bit assembly. Bit assemblies can include a bit and/or pick retained within a bore in a base block. Bit assemblies can also include a bit and/or pick retained by a bit holder and the bit holder retained within a bore in a bit holder block, hereinafter referred to as a base block. A plurality of the bit assemblies are mounted on an outside surface of a rotatable, cylindrical drum, typically in a herringbone, V-shape, or spiral configuration. A plurality of the bit assemblies can also be mounted on an endless chain and plate configuration or on an outer surface of a continuous chain. In one embodiment, the bit body of the present disclosure includes a high compression and high tensile strength forward end member that is friction welded to the bit body and machined to the desired profile. In another embodiment, the bit body of the present disclosure is a unitary piece that includes a forward end member. The bit body also includes a cutting tip insert that is mounted in a recess in the forward end member of the bit body. The cutting tip insert can include a top portion that can be designed with a generally conical, parabolic, angular, and/or somewhat flattened radius style tip profile. The combinations of bit assemblies have been utilized to remove material from the terra firma, such as degrading the surface of the earth, minerals, cement, concrete, macadam or asphalt pavement. Individual bits and/or picks, bit holders, and base blocks may wear down or break over time due to the harsh road and trenching degrading environment. In some cases the forward body portion of the bit and/or pick can be made suitable for cutting conditions that are more abrasive and require a higher hardness forward portion, while in other cases the forward portion can be made suitable for cutting conditions that contain a gaseous environment and require a non-sparking forward portion. 
     SUMMARY 
     This disclosure relates generally to a bit for mining, trenching, and/or milling equipment. One implementation of the teachings herein is a bit that includes a substantially solid body comprising a truncated forward body portion and a generally cylindrical shank depending axially from a bottom of the forward body portion; a forward portion comprising a distal end opposite a forward end of the forward portion friction welded to a first interface of the truncated forward body portion, the first interface opposite the bottom of the forward body portion; and a bore axially extending from the forward end of the forward portion to a bore termination, the bore comprising one of a generally cylindrical sidewall and a tapered sidewall curving into the bore termination. 
     In another implementation of the teachings herein is a bit that includes a base comprising one of a generally cylindrical sidewall and a tapered sidewall; a forward end comprising an apex, a first parabolic side surface adjacent the apex, and one of a second parabolic side surface and a conical side surface adjacent the first parabolic side surface. 
     In yet another implementation of the teachings herein is a bit tip insert that includes a base comprising one of a generally cylindrical sidewall and a tapered sidewall; a forward end comprising an overlay including at least one of a polycrystalline diamond, industrial diamond, natural diamond, polycrystalline diamond composite material, and polycrystalline diamond compact material. 
     In yet another implementation of the teachings herein is a bit tip insert that includes a base comprising one of a generally cylindrical sidewall and a tapered sidewall; a forward end comprising an apex, a first parabolic side surface adjacent the apex, and one of a second parabolic side surface and a conical side surface adjacent the first parabolic side surface. 
     In yet another implementation of the teachings herein is a method of manufacture of a bit that includes welding a distal end of a forward portion to an interface of a truncated forward body portion of the bit at a weld joint; and machining an outer surface of the forward portion and a bore extending axially inwardly from a forward end of the forward portion. 
     In yet another implementation of the teachings herein is a method of manufacture of a bit that includes machining an outer surface of a forward body portion of the bit and a bore extending axially inwardly from a forward end of the forward body portion. 
     These and other aspects of the present disclosure are disclosed in the following detailed description of the embodiments, the appended claims and the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various features, advantages, and other uses of the apparatus will become more apparent by referring to the following detailed description and drawings, wherein like reference numerals refer to like parts throughout the several views. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. 
         FIG. 1  is a side elevation view of a prior art bit and a prior art bit tip insert, showing invisible internal elements in dotted lines; 
         FIG. 2  is an exploded side elevation view of the prior art bit and prior art bit tip insert, showing invisible internal elements in dotted lines; 
         FIG. 3  is a side elevation view of the prior art bit and prior art bit tip insert, showing invisible internal elements in dotted lines; 
         FIG. 4  is a side elevation view of the prior art bit and prior art bit tip insert, showing invisible internal elements in dotted lines; 
         FIG. 5  is an exploded side elevation view of a first embodiment of a bit, showing a truncated bit body and a forward end member, in accordance with implementations of this disclosure; 
         FIG. 6  is a side elevation view of the first embodiment of the bit, showing the bit body and the forward end member assembled together prior to friction welding, in accordance with implementations of this disclosure; 
         FIG. 7  is a side elevation view of the first embodiment of the bit, showing the bit body and the forward end member friction welded together, in accordance with implementations of this disclosure; 
         FIG. 8  is an exploded perspective view of the first embodiment of a bit, showing the truncated bit body and the forward end member, in accordance with implementations of this disclosure; 
         FIG. 9  is a perspective view of the first embodiment of the bit, showing the bit body and the forward end member assembled together prior to friction welding, in accordance with implementations of this disclosure; 
         FIG. 10  is a perspective view of the first embodiment of the bit, showing the bit body and the forward end member friction welded together, in accordance with implementations of this disclosure; 
         FIG. 11  is a side elevation view of the first embodiment of the bit, showing the bit body and the forward end member friction welded together, in accordance with implementations of this disclosure; 
         FIG. 12  is a perspective view of the first embodiment of the bit, showing the bit body and the forward end member friction welded together, in accordance with implementations of this disclosure; 
         FIG. 13  is a side elevation view of the first embodiment of the bit, showing the forward end member of the bit being machined to a frustoconical profile, in accordance with implementations of this disclosure; 
         FIG. 14  is a perspective view of the first embodiment of the bit, showing the forward end member of the bit being machined to a frustoconical profile, in accordance with implementations of this disclosure; 
         FIG. 15  is an exploded side elevation view of the first embodiment of the bit, showing the bit and a first embodiment of a bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 16  is a side elevation view of the first embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 17  is a side elevation view of a second embodiment of a bit, showing a bit body and a forward end member friction welded together, the forward end member being machined, in accordance with implementations of this disclosure; 
         FIG. 18  is a perspective view of the second embodiment of the bit, showing the bit body and the forward end member friction welded together, the forward end member being machined, in accordance with implementations of this disclosure; 
         FIG. 19  is a side elevation view of the second embodiment of a bit, showing the forward end member of the bit being machined to a bulbous profile, in accordance with implementations of this disclosure; 
         FIG. 20  is a perspective view of the second embodiment of the bit, showing the forward end member of the bit being machined to a bulbous profile, in accordance with implementations of this disclosure; 
         FIG. 21  is an exploded side elevation view of the second embodiment of the bit, showing the bit and the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 22  is a side elevation view of the second embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 23A  is an exploded side elevation view of the first embodiment of the bit, the prior art bit tip insert, and the first embodiment bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 23B  is a side elevation view of the first embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing the prior art bit tip insert superimposed on the bit in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 24A  is an exploded side elevation view of the second embodiment of the bit, the prior art bit tip insert, and the first embodiment bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 24B  is a side elevation view of the second embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing the prior art bit tip insert and the forward end of the first embodiment bit superimposed on the second embodiment of the bit in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 25  is a side elevation view of the second embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines and showing the silhouette of the forward end of the prior art bit and the silhouette of the prior art bit tip insert in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 26  is a side elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure; 
         FIG. 27  is a detail view of Detail A of  FIG. 26  of the first embodiment of the bit tip insert in accordance with implementations of this disclosure; 
         FIG. 28  is a detail view of Detail B of  FIG. 26  of the first embodiment of the bit tip insert in accordance with implementations of this disclosure; 
         FIG. 29  is a side elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure; 
         FIG. 30  is a side perspective view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure; 
         FIG. 31  is a side perspective view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure; 
         FIG. 32  is a top elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure; 
         FIG. 33  is a side elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure; 
         FIG. 34  is a side elevation view of the first embodiment of the bit tip insert in accordance with implementations of this disclosure; 
         FIG. 35  is a side view of a plurality of bit assemblies mounted on a drum, showing the fourth embodiment of the bit and first embodiment of the bit tip insert, in accordance with implementations of this disclosure; 
         FIG. 36  is an exploded side elevation view of a third embodiment of a bit, the prior art bit tip insert, and the first embodiment bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 37  is an exploded side elevation view of the third embodiment of the bit, showing the bit and the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 38  is a side elevation view of the third embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing invisible internal elements in dotted lines, in accordance with implementations of this disclosure; 
         FIG. 39  is a side elevation view of the third embodiment of the bit, shown assembled with the first embodiment of the bit tip insert, showing the prior art bit tip insert superimposed on the bit in dotted lines, in accordance with implementations of this disclosure; and 
         FIG. 40  is a side elevation view of the first embodiment of the bit tip insert brazed into the third embodiment of the bit in accordance with implementations of this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Road mining, trenching, and milling equipment utilizes bits and/or picks traditionally set in a bit assembly. Bit assemblies can include a bit and/or pick retained within a bore in a base bock. Bit assemblies can also include a bit and/or pick retained by a bit holder and the bit holder retained within a bore in a bit holder block, hereinafter referred to as a base block. A plurality of the bit assemblies are mounted on an outside surface of a rotatable, cylindrical drum, typically in a herringbone, V-shape, or spiral configuration. A plurality of the bit assemblies can also be mounted on an endless chain and plate configuration or on an outer surface of a continuous chain. The combinations of bit assemblies have been utilized to remove material from the terra firma, such as degrading the surface of the earth, minerals, cement, concrete, macadam or asphalt pavement. Individual bits and/or picks, bit holders, and base blocks may wear down or break over time due to the harsh road and trenching degrading environment. In one embodiment, the bit body of the present disclosure includes a high compression and high tensile strength forward end member that is friction welded to the bit body and machined to the desired profile. In another embodiment, the bit body of the present disclosure is a unitary piece that includes a forward end member. The bit body also includes a cutting tip insert that is mounted in a recess in the forward end member of the bit body. The cutting tip insert can include a top portion that can be designed with a generally conical, parabolic, angular, and/or somewhat flattened radius style tip profile which provide for a better distribution of forces throughout the entire tip profile. In some cases the forward body portion of the bit and/or pick can be made suitable for cutting conditions that are more abrasive and require a higher hardness forward portion, while in other cases the forward portion can be made suitable for cutting conditions that contain a gaseous environment and require a non-sparking forward portion. 
     A prior art bit  10  and a prior art bit tip insert  12  are shown in  FIGS. 1-4 . The prior art bit  10  is substantially solid and comprises a body portion  14  and a shank  16  axially extending from a bottom of the body portion  14 . The body portion  14  comprises a tapered upper body portion  18  axially depending from a forward end  20  of the body portion  14 . Subjacent the upper body portion  18  is a mediate body portion  22  that generally slopes axially and radially outwardly to a radially extending generally arcuate tire portion  24  that terminates at a generally annular back flange  26  which denotes the bottom of the body portion  14 . 
     The shank  16  comprises a first segment  28  that slopes axially inwardly from the back flange  26  to a generally cylindrical second segment  30 . The second segment  30  axially extends from the first segment  28  to a shoulder  32  that slopes axially inwardly from the second segment  30  to a generally cylindrical third segment  34 . The third segment  34  axially extends from the shoulder  32  to a tapered distal portion  36  adjacent a distal end  38  of the shank  14 . The third segment  34  comprises an annular groove  40  adjacent the tapered distal portion  36  of the shank  14  where it can be engaged by a bit retainer (not shown) or the like. 
     The upper body portion  18  includes a tapered bore  42  that axially extends from the forward end  20  of the body portion  14  to a bore termination  44  disposed within the upper body portion  18 . The bore  42  provides a space for receiving a complementary shaped tapered outer sidewall or body  46  of the prior art bit tip insert  12 . The prior art bit tip insert  12  comprises a base  48  and a conical tip  50  at a forward end  52  of the bit tip insert  12 . The base  48  comprises the complementary shaped tapered outer sidewall or body  42  and a cylindrical distal portion  54  subjacent the outer sidewall or body  42  that extends to the distal end  56  of the bit tip insert  12 . The bit tip insert  12  is adapted to be mounted ( FIG. 3 ) and brazed ( FIG. 4 ) in the complementary shaped bore  42  of the body portion  14 . 
     This prior art bit  10  has two design flaws in the attached bit tip insert  12  region of the bit, as shown and described with reference to  FIG. 4 . The thickness at sector “F” of the bit  10  is generally determined by a thickness value that allows bit penetration into the material being removed. If sector “F” is too wide, penetration of the bit is reduced. The thickness of the frontal portion of the bit  10  at location “F” is too narrow to withstand a high value sideload at location “E”. The applied sideload at location “E” causes “B” to push away due to less sidewall support at location “B” and due to the pivot action at location “C” acting as a fulcrum lever. When a small movement occurs at location “B”, a fulcrum force at location “C” adds to the force applied at location “E” to cause the braze joint  58  ( FIG. 4 ) to fail. Braze joint failure causes much accelerated failure of the bit itself. 
     Referring to  FIGS. 5-16, 23A, and 23B , a first embodiment of a rotatable or non-rotatable substantially solid bit or tool  60  comprises a body portion  62 , which can be made of steel 15B37, 4140, 4340, or other similar suitable materials, and a shank  64  axially extending from a bottom of the body portion  62 . The body portion  62  comprises a generally cylindrical or outwardly tapered upper body portion  66  axially depending from an interface  68  ( FIGS. 5 and 8 ), such as a flat annular or generally cylindrical surface in this exemplary implementation, that defines a forward end  70  ( FIGS. 5 and 8 ) of the body portion  62 . The upper body portion  66  is generally cylindrical in this exemplary implementation. Subjacent the upper body portion  66  is a mediate body portion  72  that generally slopes axially and radially outwardly to a radially extending generally arcuate tire portion  74  that terminates at a generally annular back flange  76  which denotes the bottom of the body portion  62 . 
     The shank  64  comprises a first segment  78  that slopes axially inwardly from the back flange  76  to a generally cylindrical second segment  80 . The second segment  80  axially extends from the first segment  78  to a shoulder  82  that slopes axially inwardly from the second segment  80  to a generally cylindrical third segment  84 . The third segment  84  axially extends from the shoulder  82  to a tapered distal portion  86  adjacent a distal end  88  of the shank  64 . The third segment  84  comprises an annular groove  90 , which in this illustrated embodiment includes a flat inner surface  92  but can also have an arcuate or other shaped surface in other embodiments, adjacent the tapered distal portion  86  of the shank  64  where it can be engaged by a bit retainer (not shown) or the like. 
     A high compression and high tensile strength forward end member or nose member  94 , which can be made of steel  4140 ,  4340 , or other similar suitable materials and/or high wear, abrasive resistant, high strength alloy steel, comprises a nose body  96  that axially extends from a nose forward end  98  to an interface  100  ( FIG. 5 ), such as a flat annular or generally cylindrical surface in this exemplary implementation, defining a nose distal end  102  ( FIGS. 5 and 8 ) of the nose member  94 . The interface  100  of the nose member  94  is friction welded to the interface  68  of the body portion  62  of the bit  60 , which forms a friction welded joint  104  between the nose member  94  and the body portion  62 . In one embodiment, the body portion  62  can be made of a lesser strength steel, such as 15B37 steel which is the most commonly used steel for conical bits in mining, trenching, and highway construction. 
     The nose member  94  is machined after it has been friction welded to the body portion  62 . A machining tool insert  106 , shown in various locations as the machining tool insert  106  moves axially forward along the outer surface of the nose member  94  as the bit  60  is rotated counter clockwise, machines the outer surface of the nose member  94  to the desired profile, which in this illustrated embodiment comprises a frustoconical profile. A drill and a boring bar (not shown) are used to machine a recess or cavity  108  at the nose forward end  98  of the nose member  94 . The nose member  94  is machined using the drill to comprise the recess or cavity  108  extending axially inwardly from the nose forward end  98  to a recess termination  110  disposed within the nose member  94 . The boring bar machines the recess or cavity  108  to finish the profile of the hole  108 . An annular sidewall  114  ( FIGS. 16, 23A, and 23B ) surrounding the recess  108  comprises a weak region of the nose member  94  of this first embodiment, however, the 4340 steel of the nose member  94  at the same hardness of other steels, such as 15B37 type steels, will have about 50% greater tensile strength and yield strength. In this illustrated embodiment, the recess  108  includes a tapered sidewall  112  that curves into the recess termination  110  which is generally flat, as shown in  FIGS. 15 and 16 . The recess  108  provides a space for receiving a complementary shaped tapered outer sidewall or body  122  of a first embodiment of a bit tip insert  120 , which in this embodiment is made of tungsten carbide. 
     The first embodiment of the bit tip insert  120 , shown in  FIGS. 15, 16, and 21-34 , comprises a base  124  and a tip  126  at a forward end  128  of the bit tip insert  120 . The tip profile, which comprises a full tip radius or angular tip profile, is usually made to the same included angle of the attack angle  144  ( FIG. 29 ) of the bit holder or base block. The tip profile of the forward end  128  of the bit tip insert  120  includes a parabolic curved section  130  below an apex of the tip insert  120  and a parabolic or conical section  132  adjacent the parabolic curved section  130 . In other embodiments, the forward end  128  of the bit tip insert  120  can also have a frustoconical shape, a flat generally cylindrical puck shape, a parabolic ballistic shape, a conical shape, an angular shape, and/or an arcuate shape. 
     The tip profile of the bit tip insert  120  determines its ability to withstand applied forces. The tip geometry also determines the rate of tip wear. The greater the surface area of the tip portion, the more vertical force, rather than horizontal force, is applied to the tip, as shown in  FIG. 34 . When two different tip geometries are used in nearly the same highly abrasive, high compressive loading cutting conditions, the more robustly constructed tip geometry will outperform the other tip profile designs for various reasons: (1) a smaller tip profile does not contain a sufficient cross-sectional tip configuration to withstand variable angular impacts for removal of high compressive rock formations; (2) the narrow tip profile, by nature of its design, has a smaller tip radius and/or smaller tip profile which is followed by a transitioning sidewall that enlarges as it axially descends to a maximum diameter of the bit tip insert at about mid-length; (3) the narrow tip profile, due to its design, has poor powder processing issues when the insert is first formed during the powder pressing cycle, the forces, both horizontal and vertical, are more horizontal than vertical and not equally distributed, and the majority of the upper punch forces are applied well below the apex of the bit tip insert tip profile because the tonnage of the press is mostly consumed by the total bit tip insert surface area by the punch that forms the tip profile; and (4) a small tip profile will wear away more rapidly and develop a tip profile that approximates the same angle that the bit and/or tool engages the tierra firma or macadam, unless the holder bore wear and/or base block bore wear causes a different angle to develop. 
     The base  124  comprises the complementary shaped tapered outer sidewall or body  122  of the bit tip insert  120  that is adapted to be mounted in the complementary shaped recess  108  of the nose member  94 . The base  124  comprises a small flat bottom  134  at a distal end  136  of the bit tip insert  120 , which in this illustrated embodiment has a nominal ¼ inch diameter. The tapered outer sidewall  122  of the base  124  includes an arcuate portion  138  adjacent the distal end  136  that curves into the small flat bottom  134  of the base  124  of the bit tip insert  120 , which is complementary shaped to the tapered sidewall  112  and recess termination  110  of the recess  108 . Better heat penetration is provided to the base  124  of the bit tip insert  120 . In this illustrated embodiment, which includes a frustoconical nose profile nose member  94 , the radial stress occurring at location  116  ( FIG. 23B ) of the extended bit tip insert  120  will create greater radial stress on the sidewall  114  of the nose forward end  98  and will lead to premature bit failure. 
     Referring to  FIGS. 26-29 , the tapered outer sidewall  122  of the base  124  comprises a first plurality of circumferentially spaced protrusions  140  adjacent the tip  126  and a second plurality of circumferentially spaced protrusions  142  adjacent the distal end  136  of the base  124 , shown in detail in  FIGS. 27 and 28 . The first plurality of circumferentially spaced protrusions  140  and the second plurality of circumferentially spaced protrusions  142  adapted to provide for precision spacing between the parts, and both self-centering and self-aligning of the tip insert  120  in the recess  108  of the nose member  94  of the bit  60 . In this exemplary implementation of the first embodiment, preferably the tapered outer sidewall  122  of the base  124  is sufficiently spaced from the tapered sidewall  112  of the recess  108  of the nose member  94  to allow braze material to flow between the parts and establish the braze thickness when the bit tip insert  120  is brazed in the recess  108  of the nose member  94  of the bit  60 . The radius profile of the arcuate portion  138  of the bit tip insert  120  allows capillary action and allows melted flux material to flow freely from the base region of the bit tip insert  120  and the bottom of the recess  108  of the nose member  94  thereby producing a stronger braze joint. 
     When induction heating a steel member, the magnetic flux lines develop within the coil of the induction heating system. The magnetic flux lines excite the iron in the steel and create high heat in the steel member which then melts the braze material. The combination of the heated steel and the melted braze material transfers heat sufficiently to the tungsten carbide bit tip insert which then attaches the steel-braze-carbide together. 
     Referring to  FIGS. 17-22, 24A, 24B, 25, and 35 , a second embodiment of a rotatable or non-rotatable substantially solid bit or tool  150  is substantially the same as the bit  60  of the first embodiment with an exception that the machining tool insert  106  machines the outer surface of the nose member  94  to the desired profile, which in this illustrated embodiment comprises a bulbous profile  152  ( FIGS. 24B and 25 ) that provides greater strength than the frustoconical profile. The bulbous profile design allows lesser strength steel, such as 15B37 steel, to be used for the nose member in a bit body with lesser tensile strength and/or yield strength. The bit tip insert  120  is then brazed in the recess  108  of the nose member  94  of the bit  150 . The bulbous profile  152  ( FIGS. 24B and 25 ) of the bit body  190  can be a unitary design or can be made as a two-piece friction welded design as described with reference to the first embodiment of bit  60 . A plurality of the bit assemblies comprising the second embodiment of the bit  150  and the first embodiment of the bit tip insert  120 , mounted on an outside surface of a rotatable, cylindrical drum, are shown in  FIG. 35 . 
     Referring to  FIG. 24A , apex A-A is greater than B-B along any portion of dotted lines D, D. The bulbous design increases the thickness at “C” of the annular sidewall  114  surrounding the recess  172  without affecting bit penetration. The thickness at “C” in  FIGS. 24B and 25  is determined by the tensile strength of the steel and develops a larger and stronger profile than the frustoconical profile  118  ( FIGS. 24B and 25 ) of bit  160  in  FIG. 23 , shown by dotted lines D, D in  FIGS. 24A and 25 . The wall thickness at “F” for the bulbous design  152  is the same or less than the wall thickness at “F” for the frustoconical design  118 . 
     Referring to  FIG. 25 , the bulbous or forward bit profile  152  that increases the thickness at “C” develops an increased surface length at H-H and J-J adjacent a forward end of the bit profile to withstand greater cutting forces at location “E’. A force applied at location “E” creates a tensile component force along H-H and a compression component force along J-J. 
     Referring to  FIGS. 36-40 , a third embodiment of a rotatable or non-rotatable substantially solid bit or tool  160  comprises a body portion  162 , which can be made of steel 15B37, 4140, 4340, or other similar suitable materials, and a shank  164  axially extending from a bottom of the body portion  162 . The body portion  162  comprises, in this illustrated embodiment, an outwardly tapered upper body portion  166  axially depending from a forward end  168  of the body portion  162 . In other embodiments, the upper body portion  166  can be generally cylindrical or have other shapes. Subjacent the upper body portion  166  is a mediate body portion  170  that generally slopes axially and radially outwardly to a radially extending generally arcuate tire portion  172  that terminates at a generally annular back flange  174  which denotes the bottom of the body portion  162 . 
     The shank  164  comprises a first segment  176  that slopes axially inwardly from the back flange  174  to a generally cylindrical second segment  178 . The second segment  178  axially extends from the first segment  176  to a shoulder  180  that slopes axially inwardly from the second segment  178  to a generally cylindrical third segment  182 . The third segment  182  axially extends from the shoulder  180  to a tapered distal portion  184  adjacent a distal end  186  of the shank  164 . The third segment  182  comprises an annular groove  188 , which in this illustrated embodiment includes a flat inner surface  190  but can also have an arcuate or other shaped surface in other embodiments, adjacent the tapered distal portion  188  of the shank  164  where it can be engaged by a bit retainer (not shown) or the like. 
     The outer surface of the upper body portion  166  is machined using the machining tool insert  106 , as shown in  FIGS. 13, 14, and 17-20 . The drill and the boring bar (not shown) are used to machine a recess or cavity  192  ( FIGS. 36 and 37 ) at the forward end  168  of the body portion  162 . The body portion  162  is machined using the drill to comprise the recess or cavity  192  extending axially inwardly from the forward end  168  to a recess termination  194  disposed within the upper body portion  166 . The boring bar machines the recess or cavity  192  to finish the profile of the hole  192 . In this illustrated embodiment, the recess  192  includes a tapered sidewall  196  that curves into the recess termination  194  which is generally flat, as shown in  FIGS. 36-38 . The recess  192  provides a space for receiving the complementary shaped tapered outer sidewall or body  122  of the first embodiment of the bit tip insert  120 , which in this embodiment is made of tungsten carbide. 
     In an exemplary implementation of this illustrated embodiment, the bit  160  is made of 4340 steel. The bit tip insert  120  is brazed in the recess  192  of the body portion  162  using HI-TEMP 548 (“HT-548”) braze material. When the brazing temperature reaches approximately 1800° F., the molten braze infiltrates by capillary action into the interstitial outer region of the tungsten carbide insert, thereby forming a deeper and larger surface area bond with the tungsten carbide insert, which contains tungsten, carbon, and cobalt in this exemplary implementation. When using carbon steel such as 15B37 for the bit, the braze material only bonds to the mating steel surface for which it has a strong bond relationship and there is no significant sub-surface attachment of the HT-548 braze material and the 15B37 steel. 
     The braze joint  198 , shown in  FIG. 40 , strength improves significantly when 4340 steel is used in place of 15B37 steel to join a tungsten carbide insert into the pocket or hole  192  of the bit body portion  162 . The addition of a nickel alloy, and to a lesser extent the addition of molybdenum and chromium, to the 4340 steel of the bit  160  increases the braze joint strength by a doubling of strength value. 
     The tensile strength of the 4340 steel and of the 15B37 steel, in this case, have similar tensile strength values, except that the 15B37 steel requires a higher hardness to achieve a similar tensile strength as the 4340 steel. 
     The 4340 steel of the bit  160  comprises 1.55-2.00% nickel alloy along with a small amount of molybdenum and chromium alloys. The 1.55-2.00% nickel alloy in the 4340 steel improves the attachment to the 6% nickel alloy in the low cost HT-548 braze material alloy, which is significantly lower in cost than silver braze alloy. 
     Referring to  FIG. 40 , force was applied at location “A” to determine when braze joint failure initiation would occur at location “B” using HT-548 braze material. The 15B37 steel bit would have braze joint failure initiation when 43,355 pounds of force was applied at location “A”, while the 4340 steel bit would have braze joint failure initiation when 89,410 pounds of force was applied at location “A.” The improvement of the attachment strength between the 4340 steel bit and the tungsten carbide insert with a cobalt binder using HT-548 braze material alloy and between 15B37 steel and HT-548 braze material alloy with the same tungsten carbide chemistry in the insert is about at least two fold using the 4340 steel. 
     As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. In addition, “X includes at least one of A and B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes at least one of A and B” is satisfied under any of the foregoing instances. The articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Moreover, use of the term “an implementation” or “one implementation” throughout is not intended to mean the same embodiment, aspect or implementation unless described as such. 
     While the present disclosure has been described in connection with certain embodiments, it is to be understood that the present disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.