Abrasive Tool

Abstract

Abrasive material such as diamonds are transported onto a ferromagnetic tool blank from a suspension of brazing flux and diamonds coated with ferromagnetic material. The tool blank is prepared by coating a receptor site with brazing alloy. A magnetic field is applied to the tool blank, and the coated receptor site is placed in contact with the suspension. The receptor site is heated to brazing temperatures to liquefy the coating, allowing diamonds from the suspension to be transported by magnetism to load the liquefied brazing alloy, forming a matrix at the receptor site.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to abrasive tool making process, material, or composition. More specifically, the invention relates to forming an abrasive tool.

2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98

Abrasive cutting tools such as drill bits and saw blades are subject to wear through normal usage against workpieces. The useful life of an abrasive cutting tool depends upon the material used to form the abrasive cutting surfaces of the tool. The least expensive tools are formed entirely of steel, which provides a modest life. With increased cost, tungsten carbine can be formed into the cutting edges on a steel tool, increasing tool life. However, neither steel nor carbide cutting edges have a long life when used against extremely hard workpiece materials, such as stone, concrete, ceramic tile, and refractory materials. Diamond cutting edges are durable enough to provide a satisfactory tool life when working with these hard materials. The diamonds used to form tools are crystalline. The crystal structure of a diamond can vary considerably, but the crystals provide edges that are effective for cutting, drilling, and similar abrasive treatment of hard workpieces.

The chief problem in constructing diamond edged tools is managing the diamonds, both in terms of placement and density. Forming a diamond tool requires a technique by which a large number of extremely small diamonds can be impregnated into the cutting edges of the tool. The diamonds perform the primary task of cutting the workpiece. The diamonds at the cutting surface may wear away, such as by breaking or by becoming dislodged from the tool. It is desirable for the layer of diamonds to be thick, so that new diamonds become exposed as the cutting surface wears. The diamonds may be mounted to the tool by sintering, which fuses the diamonds to the underlying metal body of the tool. Often diamonds compose only a part of the cutting edge, while another part of the cutting edge is formed of steel or carbide. In such structures, it is desirable for the steel or carbide to wear away during use at a rate that exposes the new diamonds as required.

U.S. Pat. No. 4,211,294 to Multakh teaches a technique for forming a diamond crown for a drill bit. The crown is formed in a mold in which diamonds are mixed with various metal components of a powdered metal matrix. With the addition of heat, the matrix solidifies and holds the diamonds. Metal components are selected from iron, titanium carbide, and nickel manganese in variable proportions according to the desired hardness of the matrix, so that the matrix will wear away at a suitable rate to expose fresh diamonds at the cutting surface. The diamonds in the crown can be dispersed throughout the matrix if uniformly mixed with the matrix materials in the mold. Alternatively, diamonds can be concentrated in a layer of the crown by adding a concentrated mixture of diamonds in a layer at the desired level within the mold. After the crown has been formed in the mold, it is attached to a steel drill shaft.

Impregnating diamonds into a tool can be difficult and expensive. According to a typical procedure, a slot can be formed near the metal cutting edge of the tool, diamonds can be placed into the slot, and the diamonds can be fused in place by sintering. Another technique involves forming inserts of diamond powder and then brazing those inserts into slots on the tool.

U.S. Pat. No. 6,029,544 to Katayama teaches a technique in which diamonds are loaded into slots in a slab of tungsten carbide and sintered in place, after which the slab is cut into several inserts shaped to leave residual tungsten carbine walls bordering the sintered diamond areas. The inserts are placed in slots in the tool and brazed in place, producing a tool with areas of sintered diamonds supported by tungsten carbide walls.

It would be desirable to manage the placement and density of diamonds in abrasive cutting tools by less complex methods. In particular, it would be desirable to apply diamonds in a direct forming process, where the diamonds can be applied to the tool in a desired location and in a desired density.

To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the method and apparatus of this invention may comprise the following.

BRIEF SUMMARY OF THE INVENTION

According to the invention, a method of forming an abrasive tool includes mixing brazing flux and abrasive material to form a suspension of the flux and the abrasive material, wherein the abrasive material is coated with a ferromagnetic substance. A tool blank is provided, which is formed of a ferromagnetic substance, wherein the tool blank has one or more selected receptor sites thereon for receiving abrasive material. Brazing alloy is applied to the one or more selected receptor sites. The suspension and the tool blank are contacted with one another at the one or more selected receptor sites. During the period of contact between the suspension and the receptor sites, the tool blank is caused to be magnetic; the brazing alloy on the receptor sites is caused to be in a liquefied state; and abrasive material is transported from the suspension to the liquefied brazing alloy under magnetic force of the tool blank. As a result, a matrix of abrasive material and brazing alloy is formed at the receptor sites of the tool blank. The matrix is solidified, thereby forming an abrasive tool.

According to a more specific embodiment of the invention, a method of forming an abrasive drill bit includes mixing brazing flux and abrasive material to form a suspension of the flux and the abrasive material, wherein the abrasive material is coated with a ferromagnetic substance. A drill rod blank formed of ferromagnetic substance is provided, wherein the drill rod blank has opposite proximal and distal ends. Brazing alloy is applied to the distal end of the drill rod blank. The suspension and the distal end of the drill rod blank with the applied brazing alloy thereon are contacted with one another. During the period of contact between the suspension and the drill rod blank, the drill rod blank is caused to be magnetic; the brazing alloy on the distal end of the drill rod blank is caused to be in a liquefied state; and abrasive material is transported from the suspension to the liquefied brazing alloy under magnetic force of the drill rod blank. As a result, a matrix of abrasive material and brazing alloy is formed on the distal end of the drill bit blank. The matrix solidifies, thereby forming an abrasive drill bit.

According to another, more specific embodiment of the invention, a method of forming an abrasive drill bit includes mixing brazing flux and abrasive material to form a suspension of the flux and the abrasive material, wherein the abrasive material is coated with a ferromagnetic substance. A drill rod blank formed of ferromagnetic substance is provided, wherein the drill rod blank has opposite proximal and distal ends. Brazing alloy is applied to the distal end of the drill rod blank. The distal end of the drill rod blank with the applied brazing alloy thereon is placed in selected proximity to the suspension. A magnetic field is applied to the drill rod blank, sufficient to cause the drill rod blank to be magnetic, wherein the magnetic field is of sufficient strength with respect to the selected proximity between the drill rod blank and the suspension so as to cause the magnetism of the drill rod blank to transport the coated abrasive material from the suspension to the drill rod blank. While the drill rod blank is in the selected proximity to the suspension, the distal end of the drill rod blank is caused to be at a temperature sufficient to maintain the brazing alloy on the distal end thereof in a liquefied state such that the coated abrasive material transported to the drill rod blank enters the liquefied brazing alloy, thereby forming a matrix of abrasive material and brazing alloy on the distal end of the drill bit blank, forming an abrasive drill bit. The abrasive drill bit is cooled to solidify the brazing alloy.

The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with the description, serve to explain the principles of the invention. In the drawings:

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic flow diagram showing a sequence of method steps for forming an abrasive drill bit.

FIG. 2 is a side elevational view of a tool blank carrying a mold for forming an abrasive drill bit, with the mold shown in cross-section.

DETAILED DESCRIPTION OF THE INVENTION

The invention is a method for forming an abrasive cutting tool such as a drill bit or a saw blade. Magnetism is used as a transport mechanism to draw abrasive mineral crystals to a tool blank at a preselected location, which may be referred to as a receptor site. Magnetism provides a dynamic flow of the crystals, allowing crystal volume and density to be visually observed. Further, the magnetic placement of the crystals ensures good crystal depth at the surface of the tool blank. The crystals are magnetically displaced from a liquid carrier having a viscosity that buffers the speed of crystal migration. At the receptor site of the tool blank, a liquefied receptor at the receptor site receives the migrating crystals. Controlling the volume and shape of the liquid receptor can produce a predictable size and shape in the finished cutting body. Once the crystals are transported to the tool blank, they are fixed in place by sintering or brazing.

Broadly, the invention includes all varieties of abrasive material that is attracted magnetically, including many substances known as super abrasives. Abrasive mineral crystals used on abrasive tools include at least diamonds, cubic boron nitride, and super abrasives. Due to hardness, diamonds are highly suitable for forming the cutting edges of tools that have extended tool life. The invention will be described primarily with respect to diamonds being the abrasive material, although it should be understood that invention may employ any abrasive material. The diamonds used on tools are referred to as industrial diamonds and polycrystalline diamond products, which can include synthetic diamond grit and powder. Saw blades and drill bits often use diamond grit and powder ranging from 20 to 80 mesh and configured as cubo-octahedral crystals, both coated and uncoated. Synthetic diamonds also are produced in grinding grits that are available from 30 to 500 mesh, in both coated and uncoated formats. With coated diamonds, the coating acts as a binder to help hold the grit more firmly in a bonding matrix. It has been estimated that the pull-out rate for coated grit can be reduced by 20 to 40% compared to that of uncoated grit. When coated grits have been attached to a tool blank in a bond matrix, the coated grit produces tools with improved cutting efficiency due to greater particle protrusion height. As a general rule, a greater the protrusion height corresponds to better cutting efficiency. After applying coatings to diamond particles, the protrusion height of the particles is increased by 30%. Coated diamonds often are coated with nickel and sometimes with copper. Nickel coated diamonds are made both with electrolytic cladding and with electro-less cladding. Copper cladding tends to be electrolytic. The invention employs coated diamonds, especially nickel coated diamonds, which includes a bond system employing nickel in combination with another metal such as titanium, forming TiNi alloy.

With reference to the upper left of FIG. 1, the method steps for forming a diamond tool such as a drill bit begin with providing a tool blank 10. A blank 10 provides a body that will receive diamonds at one or more selected sites on the blank. For a drill bit, the selected tool blank is a steel rod 10, or a rod formed of any metal that forms a magnet when a magnetic field is applied to it. One end of the rod will receive the diamonds and act as the boring tip of the drill bit. For a saw blade, the tool blank is a steel disc, with or without teeth, formed of such a metal that responds to an applied magnetic field by forming a magnet. The perimeter of the saw blade disc will receive the diamonds and act as the cutting edge of the saw blade. Preferably, the metal blank is formed of a ferromagnetic material, which includes such metals as nickel, iron, cobalt, gadolinium, and their alloys. The blank may be characterized as being magnetic, although as further explained below, the magnetism preferably is the product of an externally applied magnetic field. The use of such an externally applied magnetic field is preferred because considerable heat is applied to the blank, which can degrade the magnetism of a persistent magnet.

For convenience of description, the diamond drill bit will be disclosed in further detail, although it will be evident that the techniques are adaptable to saw blades, as well. One end of the steel rod will be referred to as the proximal end 12, and this end typically is engaged in a chuck to turn the finished drill bit. A second end of the steel rod will be referred to as the distal end 14, and this end typically is the working end that serves as the receptor site that will carry the diamonds. As an example, the steel rod for a small drill bit may be formed of E-45 mild steel welding rod with a length of four inches and a diameter of one-sixteenth inch. The steel rod 10 should be clean of oxidation, particularly at the receptor site 16 at the distal end 14. As a preparatory step, the steel rod may be cleaned of initial oxidation if not supplied in clean condition. Suitable cleaning methods include filing the distal rod end and sanding the distal rod end with emery cloth. Other types of abrasive cleaning or chemical washes may be employed. Cleaning the rod can be considered to be an optional step, as the rod 10 might be supplied in pre-cleaned condition. Consequently, a first necessary step of the invention is to provide a tool blank 10 having a clean receptor site 16.

When the receptor site 16 of the rod is clean of oxidation, the method advances at arrow 18 to a next step wherein the receptor site 16 is treated to prevent further oxidation. This step may be considered to be optional, as the rod 10 may be supplied with a pretreated receptor site. A suitable means of treatment is to apply a preliminary coating of an oxidation prevention compound 20 to the receptor site 16 at rod end 14. A low temperature brazing flux 20 is a suitable oxidation prevention compound and can be applied to the distal end in order to prevent new oxidation. A suitable method of application is to dip the rod 10, or at least the distal end 14, into a reservoir of the low temperature flux 20, which coats and adheres to the receptor site.

With reference to the lower left of FIG. 1, in preparation for applying diamonds to the rod end, diamonds 22 are mixed with a suitable gel or liquid to form a suspension 24. For manufacturing a small drill bit as described here, the diamonds may be diamond grit or powder. As an example, the chosen diamonds may be of 70 grit. The preferred diamonds are cubo-octahedral crystals. The cubic aspect of the crystal structure ensures that the diamonds display cutting edges regardless of orientation in the finished drill bit. The diamonds are coated with a suitable coating that is attracted to a magnetic field. I have found that, surprisingly, TiNi coated diamonds will respond to a magnetic field by being drawn toward the field. This is surprising because, as described above, the diamond industry creates the coated diamonds as an aid to holding the grit more firmly in a bonding matrix on the tool but not as a means of loading the diamonds onto the tool. An aspect of the invention is the recognition and utilization of the fact that a diamond-coated tool can be formed by drawing diamonds having a nickel coating to desired functional orientation on the working surface of a tool.

A suitable gel or liquid for forming the suspension or preliminary matrix is low temperature brazing flux 20, as previously described. The combination of coated diamonds 22 in a mass of flux 20 prepares the diamonds for brazing compatibility by preventing subsequent scorching. The suspension may be formed by placing a quantity of the flux 20 on a heat-resistant or refractory plate such as a ceramic plate 26. A quantity of diamond grit 22 is added to the flux 20 on the plate 26 and stirred to form a uniform mixture with the diamonds in suspension.

At arrow 28, the tool blank 10 is primed to receive diamonds from the suspension. The priming process is accomplished by heating the receptor area 16 of the blank to a working temperature for receiving a coating 30 of brazing alloy. A suitable brazing alloy is a 45% to 55% silver brazing alloy, although other brazing alloys may be equally suitable. In this example, the receptor area 16 is the distal end 14 of the drill rod that has been protected by a preliminary coating of the oxidation resistant flux. A minimum working temperature for brazing tends to be at least about 800° F. In practice, the expected temperature of the heated rod is likely to be about 1000° F. The heating process can be performed with a torch 34. The exact working temperature is not critical, as it will be empirically observable when the drill rod blank 10 has reached brazing temperature, sufficient to melt a portion of brazing rod 32 and to receive brazing compound 30. A brazing rod 32 formed of a selected brazing alloy is applied against the tip 14 of the rod blank during the heating process. A torch 34 or other heat source supplies sufficient energy to melt the brazing alloy and allow it to attach to and coat the distal end 14 of the rod blank, which includes the receptor site 16. The rod blank 10 is now ready to receive a charge of diamonds.

The method advances according to arrows 36 and 38, where magnetism is used to draw diamonds from the suspension 24 into the brazing alloy 30 on the one or more receptor sites 16 of the tool blank 10. While a persistently magnetic tool blank might be used, it is preferred that an external magnetic field is applied to the blank so that the strength of the field can be maintained despite the blank's being raised to a high temperature. The strength of the externally applied magnetic field influences the magnetic strength of the rod blank. A source of suitably strong external magnetic field can be applied to or through the tool blank. For example, a permanent magnet 40 can be applied to the tool blank 10, whereby the persistent magnetic field supplied by the permanent magnet now causes the tool blank 10 to be a magnet. The strength of the applied magnetic field must be great enough to cause transport of diamonds to the receptor site 16. In part, the necessary strength of the field is a product of the proximity between the rod end 14 and suspension 24 during transport. The sufficiency of the field strength is determined by empirical observation that the transport process takes place as described, below. Thus, the tool blank 10 performs as a temporary magnet having sufficient magnetic field strength to attract suitably coated diamonds from the suspension 24. The magnet or magnetic field is applied to the tool blank 10 at least during the process of drawing diamonds to the tool blank.

In order to draw diamonds from the suspension 24 to the rod end 14, a torch 34 or other heat source is applied to the distal end 14 of the rod 10 to maintain or return the brazing alloy 30 to liquid state. The same or different heat source 34 is applied to the suspension 24 of diamonds, causing the brazing flux of the suspension to assume or maintain a liquid state and raising its temperature approximately to brazing temperature. The distal end of the rod 10 and the suspension are in placed in preselected proximity to one another. The preselected proximity is preferred to be direct communication, such as by contacting the distal end 14 of the tool blank with the suspension 24 or by dipping the distal end 14 of the tool blank into the suspension 24. It is possible that under strong enough magnetic field, the diamonds could be drawn to the distal end even without direct contact between the rod end 14 and the suspension. However, direct contact between the rod end and suspension is desirable to allow visual monitoring of diamond transport at a metered rate. If desired, the rod end is dipped into the suspension, after which the rod end and suspension are simultaneously heated.

The magnetic field acting through the rod blank 10 draws diamonds from the suspension to the brazing allow on the rod end, where the diamonds enter the melted brazing alloy on the rod end. The transport mechanism can be visually observed. The rod end may be raised to a position of minimal contact with the suspension in order to clearly observe the movement of diamonds onto the rod end. Because the brazing alloy 30 on the rod end is liquid, the diamonds enter the brazing alloy as they advance toward the rod end itself under influence of the magnetic field acting through the tool blank 10.

The diamonds accumulate at the distal end 14 of the rod blank 10, forming a matrix of diamonds and brazing alloy. If desired, the rod end can be moved through the suspension in a dipping or stirring motion to speed the accumulation. As the quantity of diamonds in the matrix increases, the size of the matrix increases. The brazing alloy or matrix may form a droplet shape on the distal end of the rod blank, thereby defining an abrasive tip on the rod end. The droplet shape will have a diamond content throughout its dimensions due to the magnetic loading process.

When the desired quantity of diamonds has been drawn into the brazing alloy on the drill bit 10, the heat source is removed and the drill bit is separated from the suspension, then ending the transport process and allowing the matrix 44 to solidify. Advancing at arrow 42 to the final step of FIG. 1, the rod 10 has been transformed into a finished drill bit 46 with sintered diamond tip defined by the cooled and solidified matrix 44. A typical diamond drill bit made according to the disclosed example has a diamond-loaded tip that is about ⅛ inch thick. The drill bit may be boiled in water to remove remaining flux. Subsequent shaping or sizing may follow, if desired. However, the natural droplet shape of the tip is adequate for many drilling tasks. As the alloy wears away during use, the deeper set diamonds will be exposed. Due to the thorough loading of diamonds into the droplet of alloy 30, the drill bit is of uniform quality and has a long life.

The disclosed method allows various means of controlling the properties of the produced drill bit. One control technique is to control the amount of brazing alloy placed on the drill rod blank. A larger quantity of brazing alloy is capable of forming a larger diameter droplet on the distal end of the rod blank. Another control technique is to meter the quantity of diamonds added to the suspension, and then to deplete the suspension of diamonds, drawing substantially all of the metered quantity into the brazing alloy. A third control technique employs a known or uniform strength of magnetic field, combined with a limited amount of time allowed for the transport mechanism to take place. Another variation is made possible by removing or terminating the magnetic field, and maintaining heat on the rod tip or reheating the tip to a liquid state after the tip has been removed from the suspension. This technique allows the diamonds and brazing alloy to reach a new positional equilibrium based on the specific gravity of each. These methods may be used separately or in combination to produce drill bits or other abrasive tools of known or controlled properties.

Where a precision size of drill bit is desired, the disclosed method for forming the bit is modified by the addition of a mold, as shown in FIG. 2. A typical mold 48 may be configured as a ceramic chamber with cylindrical sides 50, an open bottom, and a top end wall 52 with central opening 54 configured to receive the rod blank 10. This ceramic mold is placed on the rod blank with the open end of the chamber facing the distal end 14. For convenience of applying brazing alloy to the blank, the mold may be temporarily elevated on the rod blank to expose the distal end. After the brazing alloy has been applied, the mold can be lowered over the distal end by sufficient distance for the open end to be positioned below the distal end by the intended dimension of the bit below the distal end of the rod. The mold, together with the distal end, is dipped into the suspension; and the magnetic field causes the diamonds to migrate to the liquid alloy as previously described. The ceramic cavity limits the diameter of the alloy droplet as it loads with diamonds. Further, the liquid alloy is maintained within the mold cavity by capillary attraction or surface tension. As a result, the diamond-loaded end of the drill bit will tend to assume the shape of the mold cavity. After the brazing alloy has solidified, the ceramic mold can be broken away to reveal the precision sized drill bit.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be regarded as falling within the scope of the invention as defined by the claims that follow.

Claims

1. The method of forming an abrasive tool, comprising:

mixing brazing flux and abrasive material to form a suspension of said flux and said abrasive material, wherein the abrasive material is coated with a ferromagnetic substance;

providing a tool blank formed of ferromagnetic substance, wherein said tool blank has one or more selected receptor sites thereon for receiving abrasive material;

applying brazing alloy to said one or more selected receptor sites;

contacting said suspension with the tool blank at said one or more selected receptor sites;

during said contact between the suspension and receptor sites, (a) causing the tool blank to be magnetic; (b) causing the brazing alloy on the receptor sites to be in a liquefied state; and (c) transporting abrasive material from the suspension to said liquefied brazing alloy under magnetic force of the tool blank;

whereby a matrix of abrasive material and brazing alloy is formed at the receptor sites of the tool blank; and

solidifying the matrix, thereby forming an abrasive tool.

2. The method of claim 1, wherein:

said abrasive material is chosen from the group consisting of diamonds, cubic boron nitride, super abrasives, and combinations thereof.

3. A method of forming an abrasive drill bit, comprising:

mixing brazing flux and abrasive material to form a suspension of said flux and said abrasive material, wherein the abrasive material is coated with a ferromagnetic substance;

providing a drill rod blank formed of ferromagnetic substance, wherein said drill rod blank has opposite proximal and distal ends;

applying brazing alloy to said distal end of the drill rod blank;

placing the distal end of the drill rod blank with said applied brazing alloy thereon in selected proximity to said suspension;

applying a magnetic field to the drill rod blank, sufficient to cause the drill rod blank to be magnetic, wherein said magnetic field is of sufficient strength with respect to said selected proximity between the drill rod blank and the suspension so as to cause the magnetism of the drill rod blank to transport said coated abrasive material from the suspension to the drill rod blank;

while said drill rod blank is in the selected proximity to the suspension, causing the distal end of the drill rod blank to be at a temperature sufficient to maintain said brazing alloy on the distal end thereof in a liquefied state such that the coated abrasive material transported to the drill rod blank enters the liquefied brazing alloy, thereby forming a matrix of abrasive material and brazing alloy on the distal end of the drill bit blank, forming an abrasive drill bit; and

cooling the abrasive drill bit to solidify the brazing alloy.

4. The method of claim 3, wherein:

silver is a component of said brazing alloy.

5. The method of claim 4, wherein:

said brazing alloy is composed of silver in a concentration ranging from 45% to 55% by volume.

6. The method of claim 3, wherein:

nickel is a component of said ferromagnetic substance that coats said abrasive material.

7. The method of claim 6, wherein:

said ferromagnetic substance that coats said abrasive material is an alloy of nickel.

8. The method of claim 7, wherein:

said ferromagnetic substance that coats said abrasive material is a TiNi alloy.

9. The method of claim 3, wherein:

said selected proximity of the distal end of the drill rod blank to said suspension is direct contact.

10. The method of claim 9, wherein:

said selected proximity of said distal end of the drill rod blank to said suspension is at least partial immersion of the distal end into the suspension.

11. The method of claim 3, wherein:

Said abrasive material is chosen from the group consisting of diamonds, cubic boron nitride, super abrasives, and combinations thereof.

12. A method of forming an abrasive drill bit, comprising:

mixing brazing flux and abrasive material to form a suspension of said flux and said abrasive material, wherein the abrasive material is coated with a ferromagnetic substance;

providing a drill rod blank formed of ferromagnetic substance, wherein said drill rod blank has opposite proximal and distal ends;

applying brazing alloy to said distal end of the drill rod blank;

contacting said suspension with the distal end of the drill rod blank with said applied brazing alloy thereon;

during said contact between the suspension and drill rod blank, (a) causing the drill rod blank to be magnetic; (b) causing brazing alloy on the distal end of the drill rod blank to be in a liquefied state; and (c) transporting abrasive material from the suspension to the liquefied brazing alloy under magnetic force of the drill rod blank;

whereby a matrix of abrasive material and brazing alloy is formed on the distal end of the drill bit blank; and

solidifying the matrix, thereby forming an abrasive drill bit.

13. The method of claim 12, wherein:

Said abrasive material is chosen from the group consisting of diamonds, cubic boron nitride, super abrasives, and combinations thereof.