US20050098355A1

US20050098355A1 - Method and apparatus for boring through a solid material

Info

Publication number: US20050098355A1
Application number: US10/937,098
Authority: US
Inventors: Gilbert Broom
Original assignee: Cutting Edge Technologies LLC
Current assignee: Cutting Edge Technologies LLC
Priority date: 2003-03-03
Filing date: 2004-09-08
Publication date: 2005-05-12

Abstract

A drill bit shaft member for tapping a hole in a blast furnace is disclosed. The drill bit shaft member comprises an elongate rod, a first fluid pressure inlet, a second fluid pressure inlet, a chamber in fluid communication with the first fluid pressure inlet and the second fluid pressure inlet, and an outlet in fluid communication with the chamber. A liquid and a gas are combined in the drill bit shaft member to form a mist to provide cooling for the drill bit shaft member. By cooling the drill bit shaft member, certain components that would normally be destroyed may be re-used.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of pending U.S. patent application Ser. No. 10/794,575, filed on Mar. 3, 2004, which claims the benefit of U.S. Provisional Application Ser. No. 60/451,510, filed on Mar. 3, 2003. This application further claims the benefit of U.S. Provisional Application Ser. No. 60/501,283, filed on Sep. 8, 2003.

TECHNICAL FIELD

The present invention relates to a method and apparatus for boring through a solid body. More particularly, the invention relates to an improved drill shaft with a liquid and gas mist cooling system to allow the drill shaft to be used multiple times.

BACKGROUND OF THE INVENTION

There are different drill bits for drilling through a variety of solid materials. Many of these drill bits are designed for particular applications. For instance, drill bits have been designed to drill through wood, metal, and concrete. In order to drill through these different materials, designers have varied the material used to produce the drill bits, the shape of the drill bits, and the speed with which the drill bit is operated.
One problem existing with many drill bits is the rate at which they will drill a hole is too slow. When the material to be drilled is difficult to penetrate, the process of boring a hole may take as long as several minutes. It is often important be able to re-use components of the drill shaft to cut down on costs and increase profits. Such is the case in drilling tap holes in metal purifying blast furnaces.
The first step in producing steel sheet, which is used in the building and construction industry, the automotive industry, the appliance industry, the electric motor industry, etc., is to produce relatively pure iron from iron ore. This process is carried out within a blast furnace. In order to maximize the productivity of a steelmaking facility, as much pure iron as possible must be produced. Many resources are expended in developing methods and procedures to increase the amount of pure iron which can be produced annually.
In developing these methods and procedures, every manufacturing variable in the blast furnace process is optimized. One of these variables is the rate at which the blast furnace can be tapped to drain molten iron from the furnace. A typical blast furnace is tapped from seven to twelve times per day seven days per week. If a drill shaft becomes damaged, the entire shaft must be replaced. The typical blast furnace tap hole takes several minutes to drill. In fact, some tap holes take as long as 15 minutes to drill.
The drilling process is also slowed by drill bit binding. Binding occurs when loosened debris created in the drilling process builds within the hole. The debris accumulates around the drill bit and freezes the drill bit within the hole preventing the drill bit from rotating within the hole.
During the drilling process, extreme heat builds because of friction and because of the external temperature. Extreme heat, such as in a steel mill, can destroy multiple drill shafts while a single hole is being drilled. Additionally, the molten steel that exits through the hole also can destroy the drill shaft.
In order to solve some of these problems, certain drill bits have been designed which have fluid passages. Pressurized air is forced through the passages toward the drill bit/solid body interface to cool the shaft assembly and blow the debris away from the drill bit and prevent binding. However, when the hole to be drilled has a substantial length, as is the case with a blast furnace tap hole, the debris continues to build because it cannot escape the hole. Additionally, the air does not provide effective heat transfer away from the drill shaft.
Prior art low-cost drill rods are described in U.S. application Ser. No. 10/133,594 for “Method and Apparatus for Boring Through a Solid Material,” now U.S. Pat. No. 6,736,226, and PCT Publication No. WO 99/39076 for “Method and Apparatus for Boring Through a Solid Material.”
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior drill rods of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a drill bit shaft member for interconnection to a drilling apparatus. The drill bit shaft member comprises a first shaft member comprising a first elongate rod having a distal end and a proximal end. The proximal end has a first fluid pressure inlet, a second fluid pressure inlet, a chamber in fluid communication with the first fluid pressure inlet and the second fluid pressure inlet, and an outlet in fluid communication with the chamber.
It is a further object of the present invention to provide a second shaft member joined to the distal end of the first shaft member. The second shaft member comprises a second elongate rod having a fluid entrance and a fluid exit. The fluid entrance is in fluid communication with the outlet of the first shaft member and the fluid exit.
It is still a further object of the present invention to provide a tubular sleeve axially disposed around the second elongate rod to form an open volume between the second elongate rod and the tubular sleeve. A first end of the tubular sleeve is adjacent to a first end of the second elongate rod and joined to the second elongate rod to form a seal with the second elongate rod.
It is still a further object of the present invention that the second elongate rod has a first port in fluid communication with the fluid entrance of the second elongate rod and the open volume.
It is still a further object of the present invention that the second elongate rod has a second port in fluid communication with the open volume and the fluid exit of the second elongate rod.
It is still a further object of the present invention to provide a drill bit joined to a second end of the second elongate rod. The drill bit is adapted for receiving a fluid pressure from the second shaft member and delivering the fluid pressure to a drill site.
It is still a further object of the present invention that a second end of the tubular sleeve opposite the first end of the tubular sleeve is adjacent to the drill bit.
It is still a further object of the present invention that a second end of the tubular sleeve opposite the first end of the tubular sleeve abuts the drill bit.
It is still a further object of the present invention to provide an exit port in the tubular sleeve in fluid communication with the open volume.
It is still a further object of the present invention that the first fluid pressure inlet is axially disposed within the second fluid pressure inlet.
It is still a further object of the present invention that the first fluid pressure inlet delivers a liquid and the second fluid pressure inlet delivers a gas.
It is still a further object of the present invention to provide a drill bit shaft member for interconnection to a drilling apparatus. The drill bit shaft member comprises an elongate rod comprising a first fluid inlet, a second fluid inlet, a chamber in fluid communication with the first fluid inlet and the second fluid inlet. A tubular sleeve is axially disposed around the elongate rod to form an open volume between the elongate rod and the tubular sleeve. A first end of the tubular sleeve is adjacent to a first end of the elongate rod and joined to the elongate rod to form a seal. A fluid exit is in fluid communication with the chamber.
It is still a further object of the present invention that the elongate rod has a first port in fluid communication with the chamber and the open volume.
It is still a further object of the present invention that the elongate rod has a second port in fluid communication with the open volume and the fluid exit.
It is still a further object of the present invention to provide an exit port in the tubular sleeve in fluid communication with the open volume.
It is still a further object of the present invention that the first fluid pressure inlet is axially disposed within the second fluid pressure inlet.
It is still a further object of the present invention that the first fluid pressure inlet delivers a liquid and the second fluid pressure inlet delivers a gas.
It is still a further object of the present invention to provide a low-cost method for drilling a tap hole in a blast furnace. The low-cost method comprises the steps of providing a first fluid pressure source, providing a second fluid pressure source, and providing a drill shaft member comprising a first fluid pressure inlet, a second fluid pressure inlet, a chamber, and a fluid exit. The method further comprises the steps of providing a drill bit interconnected to the drill shaft member, introducing a first fluid pressure from the first fluid pressure source through the first fluid pressure inlet to the chamber, introducing a second fluid pressure from the second fluid pressure source through the second fluid pressure inlet to the chamber, and mixing the first fluid pressure and the second fluid pressure within the chamber to form a mixture of the first fluid pressure and the second fluid pressure. The mixture of the first fluid pressure and the second fluid pressure is expelled through the fluid exit, and a drilling force is provided to the drill bit.
It is still a further object of the present invention that the first fluid pressure inlet is axially disposed within the second fluid pressure inlet.
It is still a further object of the present invention that the first fluid pressure is a liquid and the second fluid pressure is a gas.
It is still a further object of the present invention to provide a drill bit shaft member for interconnection to a drilling apparatus. The drill bit shaft member comprises a first shaft member comprising an elongate rod having a distal end and a proximal end and a second shaft member comprising a hollow tube. The proximal end of the first shaft member has a first fluid pressure inlet, a second fluid pressure inlet, a chamber in fluid communication with the first fluid pressure inlet and the second fluid pressure inlet, and an outlet in fluid communication with the chamber. The second shaft member is joined to the distal end of the first shaft member and has a fluid entrance and a fluid exit. The fluid entrance is in fluid communication with the outlet of the first shaft member and the fluid exit, and the fluid exit is in fluid communication with a drill bit.
It is still a further object of the present invention to provide a drill bit for use with a drill bit shaft rotating about a drilling axis. The drill bit comprises a first drilling piece and a second drilling piece joined to the first drilling piece. The first drilling piece is configured for attachment to the drill bit shaft to create fluid communication between the first drilling piece and the drill bit shaft and is adapted to rotate about the drilling axis to define a first drilling radius. The second drilling piece is in fluid communication with the first drilling piece and is adapted to rotate about the drilling axis to define a second drilling radius that is smaller than the first drilling radius.
It is still a further object of the present invention to provide a drill bit adapted for receiving a fluid pressure from the drill bit shaft and delivering the fluid pressure to a drill site, for use with a drill bit shaft rotating about a drilling axis. The drill bit comprises a first drilling piece and a second drilling piece joined to the first drilling piece. The first drilling piece is configured for attachment to the drill bit shaft and adapted to rotate about the drilling axis to define a first drilling radius. The second drilling piece is adapted to rotate about the drilling axis to define a second drilling radius that is smaller than the first drilling radius.
It is still a further object of the present invention to provide a low-cost, recoverable drill rod system for use in tapping a metallurgical blast furnace. The low-cost recoverable drill rod system comprises a first thin-walled tubular drill rod, a fluid pressure delivery tube, and a thin-walled tubular drill rod joined to the an end of the first tubular drill rod. The first thin-walled tubular drill rod has a sidewall defining a first interior chamber and having a thickness between 0.05 and 1.0 inches. The fluid pressure delivery tube is disposed within the chamber. The chamber has a larger cross-sectional area than the fluid pressure delivery tube. The second thin-walled tubular drill rod has a sidewall defining a second interior chamber in fluid communication with the first interior chamber and having a thickness between 0.05 and 1.0 inches.
It is still a further object of the present invention to provide a low-cost, recoverable drill rod system for use in tapping a metallurgical blast furnace. The low-cost recoverable drill rod system comprises a first thin-walled tubular drill rod having opposing first and second ends joined by a sidewall and a second thin-walled tubular drill rod having opposing proximal and distal ends joined by a sidewall. The first end of the first thin-walled tubular drill rod is adapted for attachment to a drilling apparatus and has an inlet for receiving a fluid pressure. The sidewall of the first thin-walled tubular drill rod has a thickness of between 0.05 and 1.0 inches and defines a first interior chamber for receiving the fluid pressure from the inlet. The second end has an outlet for transferring the fluid pressure from the first thin-walled tubular drill rod. The proximal end of the second thin-walled tubular drill rod is adapted for attachment to the second end of the first thin-walled tubular drill rod and has an entrance port in fluid communication with the outlet of the first thin-walled tubular drill rod. The sidewall of the second thin-walled tubular drill rod has a thickness of between 0.05 and 1.0 inches and defines a second interior chamber for receiving the fluid pressure from the port. The distal end has an exit port for expelling the fluid pressure from second thin-walled tubular drill rod and is also adapted for connection to a drill bit.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a cross-sectional view of a drill shaft of the present invention;
FIG. 2 is a view taken along 2-2 of FIG. 1;
FIG. 3 is a cross-sectional view of a drill shaft of the present invention;
FIG. 4 is a cross-sectional view of a drill shaft of the present invention;
FIG. 5 is a view taken along 3-3 of FIG. 4;
FIG. 6 is a cross-sectional view of a drill shaft of the present invention;
FIG. 7 is a perspective view of a drill bit of the present invention;
FIG. 8 is a cross-sectional view of a second embodiment of the drill shaft of the present invention;
FIG. 9 is a cross-sectional view of a second embodiment of the drill shaft of the present invention;
FIG. 9A is a cross-sectional taken along A-A of FIG. 9;
FIG. 10 is a cross sectional view of a second embodiment of the drill shaft of the present invention, shown in operation;
FIG. 11 is a cross-sectional view of a coupling including a liquid or mist injection tube and an air injection tube for attachment to a drilling apparatus and for use with the drill shafts of the present invention and related mechanisms;
FIG. 12 is a perspective view of a second embodiment of the drill bit of the present invention;
FIG. 13 is a view taken along 13-13 of FIG. 12;
FIG. 14 is a perspective view of a third embodiment of the drill bit of the present invention; and
FIG. 15 is a cross-sectional view of a means of connection implemented in the drill shaft of the present invention.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many different forms, there are shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.
Referring to FIG. 1, a drill bit shaft member 10 for interconnection to a drilling apparatus is shown. The drill bit shaft member 10 comprises a first shaft member 4 comprising a first elongate rod 7 having a distal end 6 and a proximal end 8. The proximal end 8 has a first fluid pressure inlet 13, a second fluid pressure inlet 15, a chamber 16 in fluid communication with the first fluid pressure inlet 13 and the second fluid pressure inlet 15, and an outlet 14 in fluid communication with the chamber 16. The first elongate rod may be an extension piece, like those set forth in U.S. application Ser. No. 10/133,594 for “Method and Apparatus for Boring Through a Solid Material,” now U.S. Pat. No. 6,736,226, which is hereby incorporated by reference herein.
The first fluid pressure inlet 13 is axially disposed within the second fluid pressure inlet 15. The first fluid pressure inlet 13 delivers a liquid and the second fluid pressure inlet 15 delivers a gas. In order to provide cooling and prevent heat damage to the drill bit shaft member 10, the liquid and the gas are delivered into the chamber 16, where they combine to form a mist or vapor, which mist can be used to cool the system during drilling. In this embodiment, the liquid is introduced into the drill bit shaft member 10 via first fluid inlet 13, which is located in the first elongate rod 7, or optionally directly into the second elongate rod 3 (this embodiment not shown). As shown, the liquid emits from the tip 32 of the first fluid pressure inlet 13, however, the system can also be configured to emit water through one or more openings in the sides of the fluid pressure inlet 13 (this embodiment not shown).
The pressure of the liquid and gas in the fluid pressure inlets 13,15 is important to ensuring the mist cooling system operates effectively. If the gas pressure is too high, the liquid pressure may not be sufficient to inject water into the pressurized gas. Typically, the liquid pressure emitting from the first fluid pressure inlet 13 is around 40 psi, and the gas pressure in the second fluid pressure inlet 15 is around 100-110 psi. Using a chamber 16 with a larger volume and/or cross-sectional area can assist in reducing the fluid pressure differential between the first 13 and second 15 fluid pressure inlets. Preferably, the inner diameter of the chamber 16 is about 0.5 to 2.0 inches, more preferably about 0.75 to 1.25 inches, and most preferably 0.75 inches, or any range or combination of ranges therein so as to ensure that the fluid pressure differential remains at an acceptable level.
This mist exits the chamber 16 via the outlet 14 of the first shaft member 4, and enters a second shaft member 2 that is joined to the distal end 6 of the first shaft member 4. The second shaft member 2 comprises a second elongate rod 3 having a fluid entrance 17 and a fluid exit 25. The fluid entrance 17 is in fluid communication with the outlet 14 of the first shaft member 4 and the fluid exit 25. Therefore, the mist exits through the outlet 14 and enters the second shaft member 2 via the fluid entrance 17.
A tubular sleeve 5 is axially disposed around the second elongate rod 3 to form an open volume 21 between the second elongate rod 3 and the tubular sleeve 5. A first end of the tubular sleeve 11 is adjacent to a first end of the second elongate rod 12 and joined to the second elongate rod 3 to form a seal with the second elongate rod 3. There is an exit port 20 in the tubular sleeve 5 in fluid communication with the open volume 21.
The second elongate rod 3 has a first port 19 in fluid communication with the fluid entrance 17 of the second elongate rod 3 and the open volume 21, so the mist travels from the fluid entrance 17 via the first port 19 to the open volume 21 that is created between the second elongate rod 3 and the sleeve 5. The second elongate rod 3 has a second port 23 in fluid communication with the open volume 21 and the fluid exit 25 of the second elongate rod 3, so the mist travels from the open volume 21 via the second port 23 to the fluid exit 25.
A drill bit 1 is joined to a second end 24 of the second elongate rod 3. The drill bit 1 is adapted for receiving a fluid pressure from the second shaft member 2 via the fluid exit 25 and delivering the fluid pressure to a drill site. The drill bit 1 has exit holes 27 located circumferentially around the drill bit 1, as well as optionally at the tip 29.
Another type of drill bit 1 with a smaller pilot part 28 is shown in FIG. 7. The drill bit of FIG. 7 has the exit hole 27 at the tip 29. The drill bit 1 of FIG. 7 may also have one or a plurality of raised nodules 30 that assist in efficient drilling.
A second end of the tubular sleeve 18 opposite the first end of the tubular sleeve 11 may be adjacent to the drill bit 1. In FIG. 1, the second end of the tubular sleeve 18 opposite the first end of the tubular sleeve 11 abuts the drill bit 1. The first and second ends of the tubular sleeve 11,18 may optionally be swedged (shaped like circular cones) to provide a tighter fit to the drill bit 1 and first elongate rod 7.
Referring to FIG. 3, a drill bit shaft member 310 for interconnection to a drilling apparatus is shown. The drill bit shaft member 310 comprises an elongate rod 303 comprising a first fluid inlet 313, a second fluid inlet 315, a chamber 331 in fluid communication with the first fluid inlet 313 and the second fluid inlet 315. The first fluid pressure inlet 313 is axially disposed within the second fluid pressure inlet 315. The first fluid pressure inlet 313 delivers a liquid and the second fluid pressure inlet 315 delivers a gas. In order to provide cooling and prevent heat damage to the drill bit shaft member 310, the liquid and the gas are mixed in the chamber 331 to form a mist that cools the system during drilling.
A tubular sleeve 305 is axially disposed around the elongate rod 303 to form an open volume 321 between the elongate rod 303 and the tubular sleeve 305. A first end of the tubular sleeve 308 is adjacent to a first end of the elongate rod 309 and joined to the elongate rod 303 to form a seal.
A fluid exit 333 is in fluid communication with the chamber 331. There is an exit port 337 in the tubular sleeve 305 in fluid communication with the open volume 321. A first port 334 may be in fluid communication with the chamber 331 and the open volume 321. A second port 335 may be in fluid communication with the open volume 321 and the fluid exit 333. Allowing mist to flow in the open volume 321 greatly reduces the heat damage to the sleeve 305 and the elongate rod 303.
The liquid and the gas are directed into the drill bit shaft member 310 via the first and second fluid inlets 313, 315, and combined in the chamber 331 to form a mist. The first and second fluid inlets 313, 315 may be located as shown, or in an extension piece (this embodiment is not shown). Instead of using the first and second ports 334, 335 to distribute the mist, the embodiment shown in FIG. 3 may optionally be made without the first and second ports 334, 335 (this embodiment is not shown). This is because the chamber 331 extends the length of the elongate rod 303, in other words, the elongate rod 303 is a hollow tube. This allows the mist to flow freely through elongate rod 303 and via the fluid exit 333 to a drill bit 301. The drill bit 301 has exit holes 327 located circumferentially around the bit as well as optionally at the tip 329.
The elongate rod may take the form of a solid rod or a hollow tube. The second elongate rod 3 shown in FIG. 1 is an example of the solid rod type, as can be seen from the cross-section shown in FIG. 2. The elongate rod 303 shown in FIG. 3 is an example of the hollow tube rod type. Depending upon the drilling situation if the hollow tube rod type is chosen, thicker-walled tubing must be used to provide the proper strength for the rod. The tubular sleeve 5, 305 is typically a hollow tube, but may vary in thickness according to the requirements of each job.
The liquid and the gas are both pressurized to force the mist to flow through the drill bit shaft member 10, 310. The flow rate and pressure of the liquid and the gas are adjustable based on the heat transfer requirements for each job. If more heat needs to be removed from the drill bit shaft member 10, 310, the flow rates of the liquid and the gas can be increased accordingly. It has been found that, generally, the liquid pressure needs to be at least 10 psi greater than the gas pressure. The ratio of liquid pressure to gas pressure, as well as liquid flow rate to gas flow rate, can be optimized to produce a desired mist consistency. In many locations, water pressure provided from a regular spigot and gas pressure provided by a portable compressor is sufficient to produce an adequate mist. Much higher pressures can also be used to produce an adequate mist.
One of the novel aspects of the present invention is that the liquid and the gas are combined in the drill bit shaft member 10, 310, itself, instead of prior to entering the drill bit shaft member 10, 310 as a premixed mist. One of the beneficial aspects of this method is that the mist should not flow back into the hammer or drill mechanism. Flow back is prevented by mixing the liquid and the gas in the drill bit shaft member 10, 310. Others have attempted to use water and air streams, but have combined them prior to entering the drill rod. In those prior attempts, the water flows through the hammer itself and causes corrosion and ice blockages during the winter. In many situations, the chosen liquid is water and the chosen gas is air. Other possible liquids that may be utilized in the present invention include water-based coolants. Other possible gases that may be utilized in the present invention include nitrogen and carbon dioxide. The choice of liquid and gas components is dependent upon their availability, as well as the situation in which the drill bit shaft member 10, 310 may be used. In some situations, it may be dangerous to use compressed air because of the oxygen content. In those situations, nitrogen gas may be used instead.
The mist acts as a heat carrier by absorbing heat from the drill bit shaft member 10, 310 and carrying it away from the drill bit shaft member 10, 310 when it exits through either the drill bit 1, 301 or the exit ports 27, 327 located on the sleeve 5, 305. The quantity of heat removed from the system is dependent upon the component chosen for the gas and liquid, as well as the flow rates of the components. An air and water mist is an ideal mist because of its ability to carry and remove heat from the system. Most of the heat is removed from the system by the liquid component, such as water. Water has two important functions for removing heat from the system. First, as a liquid and gas, water has a specific heat capacity for absorbing heat. Second, a large amount of heat is absorbed in the transformation of water from liquid to gas. The heat that is absorbed is the heat of vaporization. These two heat-absorbing functions, when combined, can remove a large amount of heat from the system. These values will vary according to the pressure of the system.
Not only is an air and water mist excellent for removing heat from the system, but it is inexpensive and readily available in most locations where the present invention may be utilized. One location that the present invention may be utilized is in steel mills. Steel mills generally have either compressed air lines or portable compressors, as well as water sources from a spigot. The water pressure can be increased as needed with a pump.
Another embodiment of the present invention for protecting the drill rod and interior shaft from heat damage consists of utilizing an insulating layer. Referring to FIG. 4, a drill bit for boring a hole through a solid body is illustrated. The drill bit 401 is shown joined to an interior shaft 403 and abutting a sleeve 405. The interior shaft may take the form of a solid rod or hollow tube. Depending upon the drilling situation if tubing is chosen, thicker-walled tubing must be used to provide proper strength. The outer sleeve is typically a hollow tube, but may vary in thickness according to each job. The bit 401 typically will attach to the interior shaft 403 and abut the sleeve 405. Between the interior shaft 403 and the sleeve 405, a paper pulp material 441 is placed for insulation. Paper pulp material such as cardboard may be utilized as an efficient insulator because its thermal conductivity is 0.07 W/mK whereas medium carbon steel is approximately 51.9 W/mK. This insulation prevents excessive heat from traveling from the sleeve 405 to the interior shaft 403 during drilling.
Paper pulp materials are ideal for drill rod applications. As evident from its thermal conductivity, cardboard is an inexpensive insulating material that will not conduct excessive heat as steel does. Paper pulp material is readily available, comes in various sizes and can also be customized for unique applications. For example, cardboard can be preformed to precisely fit around the interior shaft 403 but still be small enough to fit inside the sleeve 405. Not only is the material easily shaped, but it is inexpensive. Other insulators, such as polycarbonate may be utilized as well. The above embodiments, the misting system and the cardboard embodiment, may optionally be combined.
Additionally, the drill shaft utilized in the misting embodiment and cardboard embodiment may consist of extensions. Referring to FIG. 6, a base unit 551, an extension unit 553, and an end unit 555 may be utilized. The drill shaft 500 may exist with any number of extensions, or no extensions, as required for specific uses. In FIG. 6, notice that only the end unit 555 has an exterior sleeve 505 and an interior shaft 503. This is because usually only the end of the drill shaft is so severely damaged that it may not be re-used. Therefore, by having the end unit sleeved, minimal material is discarded after each use when the sleeve is destroyed. Also notice that the ends of the exterior sleeve are swedged to provide a tighter seal at the sleeve/drill bit interface and the sleeve/extension or base interface. The sleeve merely abuts the other pieces at these interfaces and is held in place by compression when the drill bit is attached.
When utilizing a mist, the first and second fluid inlets 13, 313, 15, 315 may extend through the entire drill bit shaft member 10, 310, or only partially. Depending on external temperatures, and heat transfer requirements, it may be desired to combine the liquid and gas to form the mist at a specific portion of the shaft.
Additional improvements have been made to prevent damage to the drill bit shaft member 10, 310 of the present invention. For example, typically, the tubular sleeve 5, 305 was significantly smaller than the drill bit 1, 301 head. This created a problem because it allowed a large space for molten steel to flow when the drill hole was finished but the drill bit shaft member 10, 310 had not yet been removed. By increasing the size of the sleeve 5, 305, so that it is only slightly smaller than the drill bit, the volume of molten steel that flows around the drill bit shaft member 10, 310 is limited, thus minimizing damage. For example, the sleeve 5, 305 could be 0-20% smaller, or more preferably 0-10% smaller than the drill bit 1, 301 head, or any range or combination of ranges therein.
Another improvement was made by increasing the length of the drill bit 1, 301. As described above, when the hole is complete, molten steel flows around the drill bit shaft member 10, 310. By lengthening the bit 1, 301, which is usually destroyed during each use, the remaining pieces of the drill bit shaft member 10, 310 may sometimes be saved and re-used.
Another aspect of the present invention is that the interior elongate rod 3, 303 is not welded to the sleeve 5, 305. Typically, the interior elongate rod 3, 303 was welded to the sleeve 5, 305 to provide a permanent leak-proof fit. By allowing the sleeve 5, 305 to be removed from the interior elongate rod 3, 303, the interior elongate rod 3, 303 may be re-used while the sleeve 5, 305 may be discarded.
An alternate embodiment of the drill shaft system of the present invention is shown in FIGS. 8-10. This drill shaft is similar in structure and operation to the above-described embodiments, with two significant differences: the drill shaft has no tubular sleeve 5 surrounding the second shaft member, and the second shaft member is a hollow, thin-walled tube, allowing the mist to flow directly through to the drill bit.
Referring to FIG. 9, a drill bit shaft member 610 is shown, comprising a first shaft member 604, a second shaft member 602, an injection mechanism 689, and a drill bit 601. The first shaft member 604 is preferably an elongate rod 607 having opposing ends, for the sake of clarity of description, a distal end 606 and a proximal end 608, and a sidewall 660 defining an interior chamber 616. The proximal end 608 has fluid pressure inlet system 689 for separately introducing a first fluid pressure and a second fluid pressure. The fluid pressure inlet system 689 includes a first fluid pressure inlet 613 and a second fluid pressure inlet 615. The chamber 616 is in fluid communication with the first fluid pressure inlet 613 and the second fluid pressure inlet 615, and an outlet 614. The first fluid pressure inlet 613, which injects liquid into the chamber 616, is preferably a tube 681 extending into the chamber 616. However, the gas supplied by the second fluid pressure inlet 615 is preferably scavenger air pressure provided by the drilling apparatus 662, in this case a drill hammer.
The first fluid pressure inlet 613 is disposed within the second fluid pressure inlet 615. (See FIG. 9A) Thus, the second fluid pressure inlet 615 may not be a elongated tube, but rather a hole or passage 663 that is slightly larger than the diameter of the first fluid pressure inlet 613, so that the scavenger air pressure from the drilling apparatus 662 is in fluid communication with the chamber 616, and can, therefore, be transferred to the chamber 616. In this example, no additional air pressure may be necessary, as the scavenger air pressure provided by the drilling apparatus 662 is, in most instances, sufficient. In other words, the fluid pressure inlet system 689 may simply be a single hole or passage 663 through which a tube 681 delivering the first fluid pressure passes, and that is larger in cross-sectional area than the tube 681 to allow the second fluid pressure to enter the chamber 616. Preferably, the tube 681 is a water-emitting tube and the second fluid pressure is scavenger air pressure provided by the drilling apparatus 662. Alternately, the fluid pressure inlets 613,615 can be configured as previously described, operating in the same manner.
The liquid and gas combine in the chamber 616 to form a mist or vapor, preferably a water mist or vapor, which exits the first shaft member 604 through the outlet 614, entering the second shaft member 602. The proximal end 608 is attached or joined to a drilling apparatus 662, preferably directly attached or joined to a drill hammer or other force-applying mechanism, as illustrated in FIG. 8, which shows the first shaft member 604 attached to a coupling 664 threaded into the drill hammer 662. As illustrated in FIG. 9, an anti-lock nut 665 may also be used in connecting the first shaft member 604 to the drill hammer (not shown).
The first shaft member 604 can be a hollow, thin-walled tube. The thickness of the sidewall 660 of the tubular first shaft member 604 is preferably between 0.05 and 1.20 inches. More preferably, the thickness of the sidewall 660 is between 0.05 and 1.0 inches. Still more preferably, the thickness of the sidewall 660 is between 0.10 and 0.80 inches, and most preferably, is 0.135 inches, or any range or combination of ranges therein. It is a goal of the present invention to recover or reuse at least the first shaft member 604.
The second shaft member 602 is preferably a hollow, thin-walled tube 603 joined to the distal end 606 of the first shaft member 604. Similar to the first shaft member 604, the second shaft member 602 includes opposing ends separated by a sidewall 666 which defines an interior chamber 690. As shown, the tube 603 has a fluid entrance 617 and a fluid exit 625 at opposing ends, in fluid communication with each other. The fluid entrance 617 is in fluid communication with the outlet 614 of the first shaft member 604 and with the fluid exit 625, and the fluid exit 625 is in fluid communication with the drill bit 601. The mist enters the second shaft member 602 through the fluid entrance 617 and flows through the chamber 690 to the fluid exit 625, where it enters the drill bit 601. The drill bit 601 is joined to the end of the second shaft member 602, and is adapted for receiving fluid pressure from the second shaft member 602 and delivering the fluid pressure to a drill site. In this embodiment, the thickness of the sidewall 666 of the tubular second shaft member 602 is preferably between 0.05 and 1.20 inches. More preferably, the thickness of the sidewall 666 is between 0.05 and 1.0 inches. Still more preferably, the thickness of the sidewall 666 is between 0.10 and 0.80 inches, and most preferably, is 0.135 inches, or any range or combination of ranges therein. It is believed that in some cases, the second shaft member 602 may be recoverable/reused. In any event, the sidewall 660 of the first shaft member 604 is generally thicker than the sidewall 666 of the second drill shaft member 602; however, the first 604 and second 602 drill shafts can be produced from identical tubular stock.
The drill shaft 610 in FIG. 8 further includes a third shaft member 667, which acts as an extension shaft between the first shaft member 604 and the second shaft member 602. One end of the third shaft member is joined to the first shaft member 604, and the opposing end is joined to the second shaft member 602. The third shaft member shown in FIG. 8 has a fluid entrance 668 and a fluid exit 669 at opposing ends, in fluid communication with each other. The fluid entrance 668 is in communication with the outlet 614 of the first shaft member 604, and the fluid exit 669 is in communication with the fluid entrance 617 of the second shaft member 602. A greater number of extension shafts can be implemented between the first and second shaft members as part of the drill shaft, to increase its length as needed.
The drill shaft 610 in FIGS. 8-10 can be used without a protective sleeve as described above with respect to other embodiments. In this configuration, the second shaft member 602 normally cannot be preserved after opening a taphole in a blast furnace, as the molten iron will cause significant damage to the shaft. However, the mist cooling effectively cools the shaft, allowing it to retain its integrity until the skull of the taphole is broken, enabling a hole to be drilled using a single drill shaft of much lighter gauge and grade than prior drill shaft members. Conventional drill rods used in the industry today typically are made of Grade 1083 steel and have an inner diameter (ID) of 0.3125 to 0.375 inches and an outer diameter (OD) of 1.25 to 1.375 inches, resulting in an average weight of 4.0 lb/ft, and an average price of $3.10 to $5.00/ft. The mist-cooled shaft described above is typically made of Grade 1018 steel and has an ID of 1.238 inches and an OD of 1.5 to 1.625 inches, resulting in an average weight of 1.96 to 2.89 lb/ft, and an average price of $1.00/ft. The typical total shaft weight is reduced from 40 lbs. to 12 lbs. Thus, the mist-cooled shaft offers advantages both in economy and weight.
The second shaft member 602 is preferably connected to the drill bit 601 in a threadless spindle-pin connection, due to the light gauge of the second shaft member 602, as shown in FIGS. 8-10. In this configuration, the drill bit 601 is designed with a male threadless spindle 670, which is inserted into the light gauge second shaft member 602 and then welded and/or pressed to the shaft member 602 at the base head of the drill bit 601. For added strength, a pin 671 is preferably installed through the spindle 670 and tack welded at the tube's point of connection. The spindle 670 is preferably a solid pipe or rod with a hole or port 672 drilled through its length; however, one ordinarily skilled in the art would appreciate that the spindle can be produced from any suitable material that is capable of providing strength, withstanding temperature, and/or achieving the desired connection.
The second shaft member 602 is also preferably connected to the first shaft member 604 by a spindle piece 670. The spindle piece 670 preferably has one end male-threaded 674 for connection to the female-threaded first shaft member 604, and one unthreaded end 673. The unthreaded end 673 is inserted into the second shaft member 602 and again welded and/or pressed to the second shaft member 602. An anti-lock nut 665 is installed between the two ends of the spindle 670, to absorb the force of the impacts generated during drilling at the connection point of the shaft members 602,604. Like the drill bit end, a pin 670 has been installed through the spindle 670 and tack welded at the tube's point of connection.
The pin 671 has two other functions in addition to providing more strength in the connections. First, the pin 671 acts as fluid pressurizer within the chamber 616, as emission pressure is measurably enhanced with the pin 671 in place. Second, the pin 671 also adds a safety feature of blocking any molten iron that may enter the drill shaft 610 when opening the taphole, as the pin 671 acts as a barrier within the drill shaft 610. Further, any molten iron which may enter the shaft 610 is pushed toward the walls of the shaft 610, which are cooled by the mist, reducing damage.
Additionally, a short protective sleeve 675 is preferably installed at the fore end of the anti-lock nut 665, welded to the second shaft member 602. The short sleeve 675 acts as a guard to minimize the splatter of any molten iron at the connection point of the spindle 670 and second shaft member 602 shaft into the first shaft member 604. The short sleeve 675 is also a barrier to heat damage at this critical point of connection.
Alternately, the drill bit 601 can be attached to the second shaft member 602 via a nut/pressing connection, in which the drill bit 601 is pressed onto the second shaft member 602. This connection (not shown) allows a reduction in cost as the spindle does not have to be made. However, it also does not allow for the drill bit 601 to be taken off of the shaft. Similarly, the second shaft member 602 can be connected to the first shaft member 604 via a nut/pressing connection. In this connection (not shown), the second shaft member 602 is pressed into a female nut, which is threaded onto a spindle positioned in the first shaft member 604. This configuration avoids the necessity of making every shaft member with a spindle connection, and can therefore offer cost advantages. Still further, the second shaft member 602 can alternately be male-threaded for connection to a female-threaded drill bit 601, as shown in FIG. 13, particularly if a heavier gauge steel tube is used. While these connections are not shown, one ordinary skilled in the art would understand the principles of these methods.
Another alternate means of connection that can be implemented effectively with the present drill shaft is to use a separate connecting rod 676, as illustrated in FIG. 15. A solid rod 676 having a hole 677 drilled through the center attached at one end by threading to the first shaft member 604. Alternately, the solid rod 676 may be so attached to any member of the drill shaft 601, for example the drill bit (not shown), and may be attached by any suitable means, such as welding. As shown in FIG. 15, the opposite end of the solid rod 676 is inserted in the second shaft member 602. A hole 678 is drilled through the second shaft member 602 and into the solid rod 676, and a ball bearing 679 is inserted into the hole 678 and welded there to fix the second shaft member 602 to the solid rod 676. An anti-lock nut 665 is also inserted between the first 604 and second 602 shaft members. Additionally, a sleeve (not shown) may be used to protect the ball bearing connection. The sleeve can be connected using any suitable method, including but not limited to welding, friction, threading, chemical adhesive, etc.
Still further effective means of connecting elements of the drill shaft include welding or known male-female threading and connecting arrangements, as well as other known connecting means commonly implemented in the industry.
Referring to FIG. 11, a coupling 680 for supplying liquid and gas to the first 613 and second 615 fluid pressure inlets is illustrated. A water tube 681, which supplies pressurized water to the first fluid pressure inlet 613 from an external source (not shown), is affixed to a T-fitting 682 that includes an auxiliary air inlet 683 to an air passage 684. The external source may be a pressure-cleaner, to increase the pressure as necessary. The T-fitting 682 is then affixed to a hex nut 685 with a threaded bolt 686, and the water tube 681 passes through the hex nut 685 and bolt 686. Brass fittings 687 are used to affix the tube 681 to the T-fitting 682 and to affix the T-fitting 682 to the hex nut 685. The bolt 686 is threaded into the drill hammer (not shown) so that the water tube 681 passes into and through the drill hammer and into the first shaft member 604, where the first fluid pressure inlet 613 is preferably located. The water tube 681 preferably has a smaller diameter/size than the air passage 684 and second fluid pressure inlet 615 to allow auxiliary fluid pressure and/or a scavenger fluid pressure to enter the system. When inserted completely into the drill hammer, the tip of the bolt abuts a portion 688 of the drill hammer, which allows the water tube and the air passage to extend through the drill hammer.
An alternate embodiment of the drill bit of the present invention is illustrated in FIGS. 12 and 13. This drill bit is similar in structure and operation to the drill bit shown in FIG. 7 and described above, with one significant difference: the addition of openings between the first and second drilling pieces of the bit to allow delivery of fluid pressure therethrough.
Referring to FIGS. 12 and 13, a drill bit 701 is shown, comprising a first drilling piece 748 configured for attachment to a drill shaft and a second drilling piece 736 joined to the first drilling piece 748. When the drill bit 701 is attached to the drill shaft, the first 748 and second 736 drilling pieces rotate on the same axis as the drill shaft, described herein as the “drilling axis” 739. When rotating, each drilling piece 748,736 defines a drilling radius, which is the radius of the hole created by the drilling piece in each stage of drilling. Generally, the drilling radius is equal to the greatest distance any part of a piece extends from the drilling axis 739. The drilling radius of the second drilling piece 736 is advantageously smaller than the drilling radius of the first drilling piece 748, allowing the second drilling piece 736 to start a small (pilot) hole, and the first drilling piece 748 to then widen the hole. Drilling is thereby facilitated because the force upon each drilling piece is spread over a smaller area, creating less resistance. Preferably, the first 748 and second 736 drilling pieces are geometrically similar, i.e., they are directly proportional to each other in size when viewed along the drilling axis 739. Most preferably, the first 748 and second 736 drilling pieces are both hexagonally-shaped and offset 30° from each other. The corners of the hexagonal pieces serve as serrating edges during drilling. Additionally, the first and second drilling pieces are preferably joined and locked in place by a side pin 40 (FIG. 7).
The drill bit 701 is adapted for receiving a fluid pressure from the drill shaft and delivering the fluid pressure to the drill site. Preferably, the first drilling piece 748 is in fluid communication with the second shaft member 602, and the second drilling piece 736 is in fluid communication with the first drilling piece 748. In the drill bit 1 shown in FIG. 7, the fluid pressure is delivered to the drill site through an opening 27 in the tip 29 of the drill bit 1. In the drill bit 701 shown in FIGS. 12 and 13, the fluid pressure is delivered both through an opening 727 in the tip 729 of the drill bit 701 and through openings 750 located at the periphery of the second drilling piece 736. As shown, these openings 750 are located between the first drilling piece 748 and the second drilling piece 736. Some of the openings 750 also include relief ports 742, which are milled edges along the surface and sides of the bit 701, to provide dust relief, air paths for more comprehensive cooling, and additional edges for impact during drilling.
The drill bit 701 shown in FIG. 13 is configured to be attached to the drill shaft by inserting the drill shaft (not shown) into a threaded opening 744 in the drill bit 701. Further, the first drilling piece 748 is configured to create a space 743 between the openings 750 and the drill bit shaft. In the drill bit 701 shown, this is done by leaving a distance 743 between the threading 744 of the drill bit 701 and the inner ends of the openings 752. Often in such bits, the drill rod will torque into the openings 750 during drilling, blocking the fluid flow. By creating the distance 743 between the thread 744 and the openings 750, the rod cannot torque to block the openings 750.
The drill bit 701 illustrated in FIGS. 12 and 13 contains several nodules 730 on the top 745 and side surfaces 746, like the drill bit 1 illustrated in FIG. 7. These nodules 730 are preferably either carbide drilling points 747 or stellite weld beads 734, and most preferably, the drill bit 701 includes a combination of both types of nodules 730, as shown in FIG. 13. The carbide drilling points 747 are countersunk and brazed to the drill bit surfaces, while the stellite beads 734 are welded to the surface. Carbide points offer the advantage of greater hardness and durability. However, the carbide points are very expensive, and present greater difficulty attachment to the drill bit 701. Not only are the carbide points more time-consuming to attach to the bit 701, but they also occasionally fall out during drilling when the heat is sufficiently high to melt the brazing material.
A further alternate embodiment of the drill bit of the present invention is illustrated in FIG. 14. This drill bit is similar in structure and operation to the drill bits shown in FIGS. 7, 12, and 13, but contains a greater number of drilling pieces than the two-piece bits described above.
Referring to FIG. 14, a drill bit 801 is shown, comprising a first drilling piece 848 configured for attachment to the drill bit shaft, a second drilling piece 836 joined to the first drilling piece 848, a third drilling piece 849 joined to the second drilling piece 836, and a fourth drilling piece 838 joined to the third drilling piece 849. As described above, each drilling piece 848,836,849,838 is adapted to rotate about the drilling axis 839 of the drill shaft, defining a drilling radius for each. The drilling pieces closer to the tip 826 of the drill bit 801 have smaller drilling radii. Thus, the fourth drilling radius is the smallest, followed by the third drilling radius, the second drilling radius, and the first drilling radius. As described above, this allows the drill bit to start with a small pilot hole, and progressively widen the hole, creating less resistance to the drill bit 801. The drill bit 801 can be designed to include any number of drilling pieces, but too great a number of drilling pieces may be impractical.
The nodules 730,830 described above can be configured to create additional drilling stages, further enhancing the effectiveness of the drill bit 701,801. The nodules 730,830 positioned on the sides 746,846 of each drilling piece extend beyond the drilling radius of the face 745,845 of the drilling piece, and thus, the nodules 730,830 create a slightly greater drilling radius, i.e. a slightly larger hole, than the face 745,845 of the drilling piece. This further reduces the area of contact for each progressive drilling piece during drilling, making it less likely that the drill will bog down or lock up. In the two-piece drill bit illustrated in FIG. 12, the nodules 730 create a four-stage drilling process, rather than the two-stage process which would occur without the nodules.
Additionally, the drill bit 801 shown in FIG. 14 is adapted for receiving a fluid pressure from the drill bit shaft and delivering the fluid pressure to a drill site, as described above.
It is still a further object of the present invention to provide a low-cost method for drilling a tap hole in a blast furnace. The low-cost method comprises the steps of providing a first fluid pressure source, providing a second fluid pressure source, and providing a drill shaft member 10 comprising a first fluid pressure inlet 13, a second fluid pressure inlet 15, a chamber 16, and a fluid exit 25. The method further comprises the steps of providing a drill bit 1 interconnected to the drill shaft member 10, introducing a first fluid pressure from the first fluid pressure source through the first fluid pressure inlet 13 to the chamber 16, introducing a second fluid pressure from the second fluid pressure source through the second fluid pressure inlet 15 to the chamber 16, and mixing the first fluid pressure and the second fluid pressure within the chamber 16 to form a mixture of the first fluid pressure and the second fluid pressure. The mixture of the first fluid pressure and the second fluid pressure is expelled through the fluid exit 25, and a drilling force is provided to the drill bit 1. The first fluid pressure inlet 13 may be axially disposed within the second fluid pressure inlet 15. The first fluid pressure may be a liquid and the second fluid pressure may be a gas.
Several alternative embodiments have been described and illustrated. A person of ordinary skilled in the art would appreciate that the features of the individual embodiments, and the possible combinations and variations of the components. A person of ordinary skill in the art would further appreciate that any of the embodiments could be provided in any combination with the other embodiments disclosed herein. Further, the terms “first,” “second,” “proximal,” “distal,” etc. are used for illustrative purposes only and are not intended to limit the embodiments in any way, and the term “plurality” as used herein is intended to indicate any number greater than one, either disjunctively or conjunctively as necessary, up to an infinite number. Additionally, the terms “joined,” “attached,” and “connected” (and variations thereof) as used herein are intended to put or bring two elements together so as to form a unit, and any number of elements, devices, fasteners, etc. may be provided between the joined or connected elements unless otherwise specified as supported by the drawings.
While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying claims.

Claims

1. A drill bit shaft member for interconnection to a drilling apparatus, the drill bit shaft member comprising:

a first shaft member comprising a first elongate rod having a distal end and a proximal end, the proximal end having a first fluid pressure inlet, a second fluid pressure inlet, a chamber in fluid communication with the first fluid pressure inlet and the second fluid pressure inlet, and an outlet in fluid communication with the chamber.

2. The drill bit shaft member of claim 1 further comprising:

a second shaft member joined to the distal end of the first shaft member, the second shaft member comprising a second elongate rod having a fluid entrance and a fluid exit, the fluid entrance in fluid communication with the outlet of the first shaft member and the fluid exit.

3. The drill bit shaft member of claim 2 further comprising:

a tubular sleeve axially disposed around the second elongate rod to form an open volume between the second elongate rod and the tubular sleeve, a first end of the tubular sleeve adjacent to a first end of the second elongate rod and joined to the second elongate rod to form a seal with the second elongate rod.

4. The drill bit shaft member of claim 3 wherein the second elongate rod has a first port in fluid communication with the fluid entrance of the second elongate rod and the open volume.

5. The drill bit shaft member of claim 4 wherein the second elongate rod has a second port in fluid communication with the open volume and the fluid exit of the second elongate rod.

6. The drill bit shaft member of claim 5 further comprising:

a drill bit joined to a second end of the second elongate rod, the drill bit adapted for receiving a fluid pressure from the second shaft member and delivering the fluid pressure to a drill site.

7. The drill bit shaft member of claim 6, wherein a second end of the tubular sleeve opposite the first end of the tubular sleeve is adjacent to the drill bit.

8. The drill bit shaft member of claim 7 wherein the second end of the tubular sleeve abuts the drill bit.

9. The drill bit shaft member of claim 8 further comprising:

an exit port in the tubular sleeve in fluid communication with the open volume.

10. The drill bit shaft member of claim 1 wherein the first fluid pressure inlet is axially disposed within the second fluid pressure inlet.

11. The drill bit shaft member of claim 1 wherein the first fluid pressure inlet delivers a liquid and the second fluid pressure inlet delivers a gas.

12. A drill bit shaft member for interconnection to a drilling apparatus, the drill bit shaft member comprising:

an elongate rod comprising a first fluid inlet, a second fluid inlet, a chamber in fluid communication with the first fluid inlet and the second fluid inlet, a tubular sleeve axially disposed around the elongate rod to form an open volume between the elongate rod and the tubular sleeve, a first end of the tubular sleeve adjacent to a first end of the elongate rod and joined to the elongate rod to form a seal, and a fluid exit in fluid communication with the chamber.

13. The drill bit shaft member of claim 12 wherein the elongate rod has a first port in fluid communication with the chamber and the open volume.

14. The drill bit shaft member of claim 13 wherein the elongate rod has a second port in fluid communication with the open volume and the fluid exit.

15. The drill bit shaft member of claim 14 further comprising:

an exit port in the tubular sleeve in fluid communication with the open volume.

16. The drill bit shaft member of claim 12 wherein the first fluid pressure inlet is axially disposed within the second fluid pressure inlet.

17. The drill bit shaft member of claim 12 wherein the first fluid pressure inlet delivers a liquid and the second fluid pressure inlet delivers a gas.

18. A low-cost method for drilling a tap hole in a blast furnace, the low-cost method comprising the steps of:

providing a first fluid pressure source;

providing a second fluid pressure source;

providing a drill shaft member comprising a first fluid pressure inlet, a second fluid pressure inlet, a chamber, and a fluid exit;

providing a drill bit interconnected to the drill shaft member;

introducing a first fluid pressure from the first fluid pressure source through the first fluid pressure inlet to the chamber;

introducing a second fluid pressure from the second fluid pressure source through the second fluid pressure inlet to the chamber;

mixing the first fluid pressure and the second fluid pressure within the chamber to form a mixture of the first fluid pressure and the second fluid pressure;

expelling the mixture of the first fluid pressure and the second fluid pressure through the fluid exit; and,

providing a drilling force to the drill bit.

19. The low-cost method of claim 18 wherein the first fluid pressure inlet is axially disposed within the second fluid pressure inlet.

20. The low-cost method of claim 18 wherein the first fluid pressure is a liquid and the second fluid pressure is a gas.

21. A drill bit shaft member for interconnection to a drilling apparatus, the drill bit shaft member comprising:

a first shaft member comprising an elongate rod having a distal end and a proximal end, the proximal end having a first fluid pressure inlet, a second fluid pressure inlet, a chamber in fluid communication with the first fluid pressure inlet and the second fluid pressure inlet, and an outlet in fluid communication with the chamber; and

a second shaft member joined to the distal end of the first shaft member, the second shaft member comprising a hollow, thin-walled tube having a fluid entrance and a fluid exit, the fluid entrance in fluid communication with the outlet of the first shaft member and the fluid exit, and the fluid exit in fluid communication with a drill bit.

22. The drill bit shaft member of claim 21, further comprising:

a drill bit joined to the second shaft member, the drill bit adapted for receiving a fluid pressure from the second shaft member and delivering the fluid pressure to a drill site.

23. A drill bit for use with a drill bit shaft rotating about a drilling axis, the drill bit comprising:

a first drilling piece configured for attachment to the drill bit shaft to create fluid communication between the first drilling piece and the drill bit shaft, the first drilling piece adapted to rotate about the drilling axis to define a first drilling radius; and

a second drilling piece joined to the first drilling piece and adapted to rotate about the drilling axis to define a second drilling radius that is smaller than the first drilling radius, the second drilling piece in fluid communication with the first drilling piece.

24. The drill bit of claim 23, further comprising a third drilling piece joined to the second drilling piece and adapted to rotate about the drilling axis to define a third drilling radius that is smaller than the second drilling radius, the third drilling piece in fluid communication with the second drilling piece.

25. The drill bit of claim 23, wherein the second drilling piece is geometrically similar to the first drilling piece.

26. The drill bit of claim 23, wherein the drill bit is adapted for receiving a fluid pressure from the drill bit shaft and delivering the fluid pressure to a drill site.

27. The drill bit of claim 26, wherein the fluid pressure is delivered to the drill site through an opening located at the periphery of the second drilling piece.

28. The drill bit of claim 26, wherein the fluid pressure is delivered to the drill site through an opening located between the first drilling piece and the second drilling piece.

29. The drill bit of claim 28, wherein the first drilling piece is configured to create a space between the opening and the drill bit shaft.

30. The drill bit of claim 26, wherein the fluid pressure is delivered to the drill site through an opening at the end of the drill bit opposite the drill bit shaft.

31. A drill bit for use with a drill bit shaft rotating about a drilling axis, the drill bit comprising:

a first drilling piece configured for attachment to the drill bit shaft and adapted to rotate about the drilling axis to define a first drilling radius; and

a second drilling piece joined to the first drilling piece and adapted to rotate about the drilling axis to define a second drilling radius that is smaller than the first drilling radius,

wherein the drill bit is adapted for receiving a fluid pressure from the drill bit shaft and delivering the fluid pressure to a drill site.

32. The drill bit of claim 31, further comprising a third drilling piece joined to the second drilling piece and adapted to rotate about the drilling axis to define a third drilling radius that is smaller than the second drilling radius.

33. A low-cost, recoverable drill rod system for use in tapping a metallurgical blast furnace, the low-cost, recoverable drill rod system comprising:

a first thin-walled tubular drill rod having a sidewall defining a first interior chamber, the sidewall having a thickness between 0.05 and 1.0 inches;

a fluid pressure delivery tube disposed within chamber, the chamber having a larger cross-sectional area than the fluid pressure delivery tube; and

a second thin-walled tubular drill rod joined to the an end of the first tubular drill rod, the second thin-walled tubular drill rod having a sidewall defining a second interior chamber in fluid communication with the first interior chamber, the sidewall of the second thin-walled tubular drill rod having a thickness between 0.05 and 1.0 inches.

34. The low-cost, recoverable drill rod system of claim 33 wherein the sidewall of the first thin-walled tubular drill rod is thicker than the sidewall of the second thin-walled tubular drill rod.

35. A low-cost, recoverable drill rod system for use in tapping a metallurgical blast furnace to remove molten iron from the blast furnace wherein at least a portion of the low-cost, recoverable drill rod system must withstand an elevated temperature caused by the molten iron, the low-cost recoverable drill rod system comprising:

a first thin-walled tubular drill rod having opposing proximal and distal ends joined by a sidewall defining a first interior chamber, the proximal end adapted for attachment to a drilling apparatus and having a fluid pressure inlet system for separately introducing a first fluid pressure and a second fluid pressure into the first interior chamber, the first interior chamber adapted for mixing the first fluid pressure and the second fluid pressure, the distal end of the first thin-walled tubular drill rod having an outlet for transferring a mixture of the first fluid pressure and the second fluid pressure from the first thin-walled tubular drill rod; and

a second thin-walled tubular drill rod having opposing first and second ends joined by a sidewall, the first end adapted for attachment to the distal end of the first thin-walled tubular drill rod and having an entrance port in fluid communication with the outlet of the first thin-walled tubular drill rod, the sidewall defining a second interior chamber for receiving the mixture of the first and second fluid pressures from the entrance port, and the second end having an exit port for expelling the mixture of the first and second fluid pressures from the second thin-walled tubular drill rod.

36. The low-cost, recoverable drill rod system of claim 35 wherein the sidewall of the first thin-walled tubular drill rod has a thickness between 0.05 and 1.0 inches.

37. The low-cost, recoverable drill rod system of claim 35 wherein the sidewall of the second thin-walled tubular drill rod has a thickness between 0.05 and 1.0 inches.

38. The low-cost, recoverable drill rod system of claim 35 wherein the sidewall of the first thin-walled tubular drill rod is thicker than the sidewall of the second thin-walled tubular drill rod.

39. The low-cost, recoverable drill rod system of claim 35 wherein the fluid pressure inlet system comprises a first inlet for transferring a liquid fluid pressure and a second inlet for transporting a gas fluid pressure.

40. The low-cost, recoverable drill rod system of claim 35 wherein the fluid pressure inlet system comprises a passage and a tube, for transferring the first fluid pressure, extending through the passage, the passage having a larger cross-sectional area than the tube to allow the second fluid pressure to enter the chamber.

41. The low-cost, recoverable drill rod system of claim 35 wherein the fluid pressure inlet system comprises a passage having a cross-sectional area large enough for receiving a water emitting tube while allowing a scavenger air pressure provided by a drilling apparatus to pass therethrough.