Patent Publication Number: US-9890595-B2

Title: Methods of forming and methods of repairing earth boring-tools

Description:
TECHNICAL FIELD 
     Embodiments of the present disclosure relate to methods of forming and methods of repairing earth-boring tools including additive and subtractive manufacturing processes. 
     BACKGROUND 
     Earth-boring tools are used to form boreholes (e.g., wellbores) in subterranean formations. Such earth-boring tools include, for example, drill bits, reamers, mills, etc. For example, a fixed-cutter earth-boring rotary drill bit (often referred to as a “drag” bit) generally includes a plurality of cutting elements secured to a face of a bit body of the drill bit. The cutters are fixed in place when used to cut formation materials. A conventional fixed-cutter earth-boring rotary drill bit includes a bit body having generally radially projecting and longitudinally extending blades. During drilling operations, the drill bit is positioned at the bottom of a well borehole and rotated. 
     Earth-boring tool bodies, such as drag bits, may have complex internal and external geometry including, e.g., internal fluid passageways and external blades with pockets for cutting elements. Earth-boring tool bodies may be formed from metal alloys such as steel, stainless steel, or other alloys. Such bits may, for example, be formed by machining (e.g., milling, turning) a metal blank to the desired geometry. To enhance the longevity of a metal alloy bit body in abrasive downhole environments, wear-resistant materials may be applied to high-wear areas of the bit body, such as the blade surfaces, gage surfaces, junk slots (i.e., fluid courses between blades), and areas adjacent the cutter pockets. Examples of wear-resistant materials may include multi-phase materials, e.g., hard material particles dispersed within a metal alloy matrix, or may include substantially homogenous metal alloys, such as cobalt-chromium alloys. The wear-resistant material may be applied by, for example, melting a rod comprising the wear resistant material with a torch or other heat source adjacent the areas of the tool body over which the wear-resistant material is desired. 
     BRIEF SUMMARY 
     In one aspect of the disclosure, a method of forming at least a portion of an earth-boring tool comprises entering an electronic representation of at least one geometric feature of at least a component of an earth-boring tool in a computer system including memory and a processor, the computer system operatively connected to a multi-axis positioning system, a direct metal deposition tool, and a material removal tool. The processor generates a first tool path for the direct metal deposition tool. The first tool path is based at least in part on the electronic representation of the at least one geometric feature of the at least a component of the earth-boring tool. The direct metal deposition tool is operated along the first tool path to deposit metal on an earth-boring tool component coupled to the multi-axis positioning system to at least partially form the at least one geometric feature of the earth-boring tool. The processor generates a second tool path for the material removal tool, the second tool path based at least in part on the electronic representation of the at least one geometric feature of the earth-boring tool. The material removal tool is operate along the second tool path to remove at least a portion of the deposited metal from the at least one geometric feature of the at least a component of the earth-boring tool. 
     In another aspect of the disclosure, a method of forming a rotary drag bit comprises entering an electronic representation of a rotary drag bit in a computer system of a multi-axis milling machine, the computer system comprising memory and a processor. A metal blank is affixed to a multi-axis positioner of the multi-axis milling machine. Material is removed from the metal blank by operating a milling tool along a milling tool path determined by the processor of the multi-axis milling machine based at least in part on the electronic representation of the rotary drag bit to form a shank of the rotary drag bit including a threaded portion for connection to a drill string. Metal material is deposited on the shank of the rotary drag bit by operating a direct metal deposition tool along a first deposition tool path determined by the processor of the multi-axis milling machine based at least in part on the electronic representation of the rotary drag bit to form a geometric feature of the rotary drag bit including at least a portion of a blade on the shank of the rotary drag bit. A hardfacing material is deposited on the at least a portion of the blade of the rotary drag bit by operating a direct metal deposition tool along a hardfacing tool path determined by the processor of the multi-axis milling machine based at least in part on the electronic representation of the rotary drag bit to form at least one hardfaced area on the at least a portion of the blade of the rotary drag bit. 
     In yet another aspect of the disclosure, a method of repairing an earth-boring tool comprises generating an electronic representation of the shape of a worn earth-boring tool. Using a computer system, the electronic representation of the shape of the worn earth-boring tool is compared to an electronic representation of a shape of the earth-boring tool in an unworn state based on design specifications associated with the earth-boring tool to identify worn areas of the earth-boring tool. Using a computer system, a tool path is generated based on a difference between the compared shape of the worn earth-boring tool and the shape of the earth-boring tool in an unworn state based on the design specifications of the earth-boring tool. A direct metal deposition tool is operated along the tool path to build up worn areas of the worn earth-boring tool to meet the design specifications. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the present disclosure, various features and advantages of disclosed embodiments may be more readily ascertained from the following description when read with reference to the accompanying drawings, in which: 
         FIG. 1  is a process flow chart showing process acts of a method of forming an earth-boring tool according to an embodiment of the disclosure; 
         FIG. 2  is a side cross-sectional view of a direct metal deposition process according to an embodiment of the disclosure; 
         FIG. 3  is a side cross-sectional view of a subtractive machining process according to an embodiment of the disclosure; 
         FIG. 4  is an elevation view of a machine tool according to an embodiment of the disclosure; 
         FIG. 5  is a perspective view of a portion of an earth-boring tool according to an embodiment of the disclosure; 
         FIG. 6  illustrates the portion of the earth-boring tool of  FIG. 5  with additional features deposited by direct metal deposition; 
         FIG. 7  illustrates the portion of the earth-boring tool of  FIG. 6  with hardfacing applied by direct metal deposition; 
         FIG. 8  illustrates the portion of an earth-boring tool of  FIG. 7  with cutting elements installed in recesses of the earth-boring tool; 
         FIG. 9  is a side cross-sectional view of an ultrasonic machining process according to an embodiment of the disclosure; 
         FIG. 10  is a side cross-sectional view of a brazing process according to an embodiment of the disclosure; 
         FIG. 11  is a perspective view of an embodiment of an earth-boring tool illustrating worn areas after use of the earth-boring tool; and 
         FIG. 12  is a schematic diagram of a manufacturing system according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The illustrations presented herein are not actual views of any particular method, apparatus, or earth-boring tool component, but are merely idealized representations employed to describe embodiments of the disclosure. Additionally, elements common between figures may retain the same numerical designation. 
     The disclosure relates to methods of forming earth-boring tools using direct metal deposition manufacturing processes. For example, the disclosure relates to layer-by-layer application of metal material on surfaces of earth-boring tool components. In some embodiments, direct metal deposition processes may be used to form earth-boring tool components. In some embodiments, direct metal deposition processes may be used to apply material to partially formed earth-boring tool components (e.g., blanks including the shank of a rotary drill bit). In some embodiments, direct metal deposition processes may be used to repair earth-boring tool components by applying material to a worn portion of the earth-boring tool component. 
     As used herein, the term “direct metal deposition” means and includes any additive manufacturing processes in which material is applied to a component by at least partially melting a portion of the component to form a melt pool, introducing additional material to the melt pool, at least partially melting the additional material, and re-solidifying the melt pool and the additional material to form a raised feature on the component. 
     As used herein, the term “earth-boring tool” means and includes any portion or component of a tool configured for use in formation degradation, e.g., drilling or enlarging boreholes for oil or gas production, geothermal wells, mining, etc. Such tools may include, without limitation, rotary drag bits, roller cone drill bits, hybrid bits, reamer components such as reamer blades, and other tools. 
       FIG. 1  illustrates a flow chart of a non-limiting example method  100  of forming a portion of an earth-boring tool according to an embodiment of the disclosure. In act  101 , an electronic representation of at least one geometric feature of at least a component of an earth-boring tool is entered in a computer system including a memory and a processor, the computer system operatively connected to at least one of a multi-axis positioning system, a direct metal deposition tool, and a material removal tool. In act  102 , the processor generates a first tool path for the direct metal deposition tool. The first tool path is based at least in part on the electronic representation of the at least one geometric feature of the at least a component of the earth-boring tool. In act  103 , the direct metal deposition tool is operated along the first tool path to deposit metal on an earth-boring tool component coupled to the multi-axis positioning system to at least partially form the at least one geometric feature of the earth-boring tool. In act  104 , the processor generates a second tool path for the material removal tool. The second tool path is based at least in part on the electronic representation of the geometric feature. In act  105 , the material removal tool is operated along the second tool path to remove at least a portion of the deposited metal from the at least one geometric feature of at least a component of the earth-boring tool. 
       FIG. 2  illustrates a simplified cross-sectional view of an embodiment of a direct metal deposition process used to form a portion of an earth-boring tool. An earth-boring tool component  110  may be affixed to a machine tool component configured to position and/or manipulate a workpiece, such as a multi-axis positioner  112 . As a specific, non-limiting example, the multi-axis positioner  112  may be a component of a multi-axis, computer-numeric-control (CNC) machine tool. In other words, the multi-axis positioner  112  may be operatively (e.g., mechanically, electrically) coupled to the multi-axis machine tool. The multi-axis machine tool may include a CNC processor (not shown) programmed to read an electronic file representing a three-dimensional model of an earth boring tool, and to generate tool paths based at least in part on the three-dimensional model for one or more machine tools (e.g., additive manufacturing tools, subtractive manufacturing tools) operatively connected to the multi-axis positioner  112 , as described below. The additive manufacturing tools and subtractive manufacturing tools may be operated along respective tool paths to form geometric features of the earth-boring tool. The tool paths may include movement (e.g., linear movement in direction  128 ) of the multi-axis positioner  112 , which may be controlled by the CNC processor through motors (e.g., stepper motors), linear actuators, or other electromechanical devices. 
     The earth-boring tool component  110  may be, e.g., a portion of an earth-boring drill bit (e.g., a drag bit, a roller cone bit, a hybrid bit, etc.), a portion of a borehole enlarging device (e.g., a reamer blade), or any other component of an earth-boring tool. The earth-boring tool component  110  may comprise a metal alloy, such as steel, stainless steel, a nickel-based alloy, or other metal alloys. In some embodiments, the earth-boring tool component  110  may comprise a particle-matrix composite material, such as particles of cemented tungsten carbide dispersed within a metal alloy matrix (e.g., a bronze matrix). 
     An additive manufacturing device may be operatively coupled (e.g., mechanically and/or electrically coupled) to the multi-axis positioner  112 . As non-limiting examples, the additive manufacturing tool may be or include one or more tools configured to implement direct metal deposition, micro-plasma powder deposition, selective laser melting, selective laser sintering, electron beam melting, electron beam freeform fabrication, and other additive manufacturing processes. In the embodiment shown in  FIG. 2 , the additive manufacturing tool is a direct metal deposition tool  114 . The direct metal deposition tool  114  may include a heat source  116  and one or more deposition nozzles  118  may be positioned adjacent the earth-boring tool component  110 . The heat source  116  may comprise a laser, an electron beam, plasma arc, or any other suitable heat source. In the embodiment shown in  FIG. 2 , the heat source  116  is a CO 2  laser. In another embodiment, the heat source  116  may be separate and distinct from the direct metal deposition tool and be independently positionable with respect to the earth-boring tool component  110  for optimal selective heating of a portion of the surface of the earth-boring tool component  110 . 
     The one or more deposition nozzles  118  may be configured to deliver material for deposition on the earth-boring tool component  110 . For example, the one or more deposition nozzles  118  may be operably connected to one or more reservoirs (not shown) containing powdered metal material  120 . In some embodiments, a fluid medium may be used to deliver the powdered metal material  120  from the one or more reservoirs through the one or more deposition nozzles  118 . For example, particles of the powdered metal material  120  may be entrained within a flow of inert gas (e.g., argon) and delivered by the flow of inert gas through the one or more deposition nozzles  118 . In other embodiments, metallic material may be delivered in non-powdered form, e.g., as a wire or rod of material. 
     The heat source  116  and the one or more deposition nozzles  118  may be affixed to a gantry  122  positioned adjacent the multi-axis positioner  112 . In some embodiments, the gantry  122  may include computer-numeric-control (CNC) capability. For example, the gantry  122  may be configured to enable linear movement of the direct metal deposition tool  114  in one or more linear directions and rotational movement of the direct metal deposition tool  114  about one or more axes. In some embodiments, the gantry  122  may be affixed to electromechanical devices, e.g., stepper motors, linear actuators, etc., that are operatively connected to the CNC processor and move the gantry  122  and the direct metal deposition tool  114  along a tool path generated by the CNC processor based on the three-dimensional model of the earth-boring tool. 
     During operation of the direct metal deposition tool  114 , the heat source  116  may initiate a melt pool  124  by heating a localized portion of a surface  126  of the earth-boring tool component  110  to a melting temperature of a material of the surface of the earth-boring tool component  110 . The one or more deposition nozzles  118  may deliver particles of powdered metal material  120  to the melt pool  124 . The particles of powdered metal material  120  may at least partially melt upon contact with the melt pool  124 , or may at least partially melt when in proximity to one or both of the melt pool  124  and the heat source  116 . Subsequent solidification of the melt pool  124  after the addition of the powdered metal material  120  results in build-up of the surface  126  of the earth-boring tool component  110 . In other words, the direct metal deposition process illustrated in  FIG. 2  results in additional material  130  being deposited on the surface  126  of the earth-boring tool component  110 . The additional material  130  deposited on the surface  126  of the earth-boring tool component  110  may be characterized as a “layer” of additional material. However, as the powdered metal material  120  may be completely melted and incorporated in the melt pool  124  in some embodiments, the additional material  130  and the material of the earth-boring tool component  110  may be substantially homogenous. 
     The amount of additional material  130  deposited in one pass by the direct metal deposition tool  114  may be varied by changing operational parameters of the direct metal deposition tool  114 , the gantry  122 , and the multi-axis positioner  112 . For example, the amount of additional material  130  deposited in one pass may be adjusted by altering the flow rate of the powdered metal material  120  and/or a rate of travel of the surface  126  of the earth-boring tool component  110  with respect to the direct metal deposition tool  114  (e.g., one or both of a rate of travel of the multi-axis positioner  112  and a rate of travel of the gantry  122 ). A desired final geometry may be imparted to the earth-boring tool component  110  by applying material to the earth-boring tool component  110  by making one or more passes with the direct metal deposition tool  114  to build up various surfaces and features. Stated differently, the direct metal deposition tool  114  may be used to impart one or more geometric features  131  to the surface  126  of the earth-boring tool component  110  by depositing or more layers of additional material  130  on the surface of the earth-boring tool component  110 . The one or more geometric features formed by the direct metal deposition tool  114  may be fully dense on completion of the direct metal deposition process. In other words, the one or more geometric features  131  may be substantially free of porosity. 
     The direct metal deposition tool  114  may include a closed-loop control system. For example, the direct metal deposition tool  114  may include sensors (not shown) that monitor operating conditions such as melt pool temperature, melt pool size, or other conditions. Data related to the operating conditions measured by the sensors may be sent to a direct metal deposition control processor (e.g., the CNC processor or a different processor), which may evaluate the data and increase or decrease the power provided to the heat source  116  to modify the temperature and/or size of the melt pool  124 . In some embodiments, the closed-loop control system may include optical sensors, proximity sensors, distance sensors or other sensors to monitor the dimensions and geometry of the additional material  130  deposited by the direct metal deposition tool  114 . Data from the sensors monitoring the dimensions and geometry of the additional material  130  may be sent to the CNC processor, and the CNC processor may alter the tool path of the direct metal deposition tool based on the data when the dimensions and geometry of the additional material  130  deviate a predetermined amount from design specifications (e.g., the dimensions and geometry specified by the electronic representation) of the earth-boring tool. 
     In some embodiments, the earth-boring tool component  110  may be a partially formed earth-boring tool, for example, the shank of a rotary drill bit, formed using processes such as machining, casting, etc. In some embodiments, the earth-boring tool component  110  may be formed completely by direct metal deposition, and the earth-boring tool component  110  may represent a portion of an earth-boring tool formed during previous passes of the direct metal deposition tool  114 . In other words, the earth-boring tool component  110  may be formed completely by the direct metal deposition tool  114 . 
     At the completion of the direct metal deposition process, the earth-boring tool component  110  may have a near-net shape. In other words, the geometric features of the earth-boring tool component  110  formed by direct metal deposition may exhibit manufacturing tolerances that vary from design specifications of the earth-boring tool component  110  by less than the variance exhibited by some other forming processes (e.g., casting). Nevertheless, it may be necessary to perform subtractive manufacturing processes (e.g., machining) on one or more of the geometric features of the earth-boring tool component  110  created by the direct metal deposition process to achieve acceptable tolerances with respect to design specifications of the earth-boring tool component  110 . For example, geometric features of the earth-boring tool component  110  may be finish machined by milling, drilling, routing, turning, etc. In some embodiments, finish machining operations may be used to form negative features of the earth-boring tool component  110 , such as cutting element pockets  150  ( FIG. 6 ) and fluid nozzle receptacles  152  ( FIG. 6 ). Furthermore, depending on the resolution (e.g., the amount of material deposited in each pass by the direct metal deposition tool  114 ) of the direct metal deposition process, discontinuities  133  (e.g., “steps” between deposited portions) may exist on the surface of the geometric features of the earth-boring tool component  110 . Subtractive manufacturing operations may be used to smooth the surface of the geometric feature  131  and at least partially remove the discontinuities  133 . 
     In some embodiments, the earth-boring tool component  110  may remain affixed to the multi-axis positioner  112  during finish machining operations. For example, the gantry  122  ( FIG. 2 ) may be moved (e.g., translated, pivoted) away from the earth-boring tool component  110 , and a machine tool  132  ( FIG. 3 ) may be moved into position to machine the earth-boring tool component  110 . In the example of  FIG. 3 , the machine tool  132  shown is an end mill; however, other machine tools such as mills, drills, and other cutting tools may be used to machine the earth-boring tool component  110 . 
     The direct metal deposition tool  114 , the machine tool  132 , the multi-axis positioner  112 , and other tools may be associated with a single production station. For example, the direct metal deposition tool  114 , the machine tool  132 , and other machine tools may be affixed and operatively (e.g., mechanically, electronically) connected to a tool such as a multi-axis mill  136 , as shown in  FIG. 4 . Thus, both additive manufacturing (e.g., material deposition with direct metal deposition tool  114 ) and subtractive manufacturing (e.g., machining with machine tool  132 ) processes may be performed on the earth-boring tool component  110  while the earth-boring tool component remains positioned within a working envelope  134  of the multi-axis mill  136 . Suitable tools, e.g., multi-axis machine tools including at least a direct metal deposition tool and a machine tool, are available from, for example, DM3D Technology LLC, 2350 Pontiac Rd., Auburn Hills, Mich. USA; Optomec, 3911 Singer N. E., Albuquerque, N. Mex. USA; DMG Mori USA, 2400 Huntington Blvd., Hoffman Estates, Ill. USA; and Mazak Corp., 8025 Production Drive, Florence, Ky. USA. Such tools may be equipped with CNC capabilities as described above. For example, such tools may include a CNC processor configured to generate tool paths for one or more of the multi-axis positioner  112 , the direct metal deposition tool  114 , the machine tool  132 , or other tools based on the electronic representation (e.g., 3-dimensional computer model) of the desired final geometry of the earth-boring tool component  110 . 
     The direct metal deposition tool  114  ( FIG. 2 ) may be used to apply one or more different metal materials to the earth-boring tool component  110 . For example, the direct metal deposition tool  114  may be used to apply material having a composition similar or identical to a material of the earth-boring tool component  110 . In some embodiments, the metallic material applied to the earth-boring tool component  110  and the material of the earth-boring tool component  110  may be a metal alloy such as steel, stainless steel, bronze, a nickel-based alloy, or other metal alloys. 
     The direct metal deposition tool  114  ( FIG. 2 ) may also be used to apply materials different from a base material of the earth-boring tool component  110 . For example, the direct metal deposition tool  114  may be used to apply metals or metal alloys having a different composition from the material of the earth-boring tool component  110 . In other words, the earth-boring tool component  110  may comprise a metal alloy, e.g., steel, and the additional material  130  deposited by the direct metal deposition tool  114  may comprise a metal alloy different from that of the earth-boring tool component  110 . 
     In some embodiments, the earth-boring tool component  110  may include hardfacing material to impart abrasion resistance to high-wear areas. The hardfacing material may comprise a particle-matrix composite material, such as particles of cemented tungsten carbide dispersed within a metal alloy matrix phase. Additionally or alternatively, the hardfacing material may comprise a metal alloy material such as a wear-resistant cobalt-chromium alloy (e.g., STELLITE®, available from Kennametal, Inc., Latrobe, Pa., USA). 
     Hardfacing material may be applied to the earth-boring tool component  110  in a similar manner to that described above in connection with the application of metal alloy material to the earth-boring tool component  110  in  FIG. 2 . For example, the heat source  116  may be used to form a melt pool  124  in the surface  126  of the earth-boring tool component  110 , and the hardfacing material may be delivered in powdered form through the one or more deposition nozzles  118  of the direct metal deposition tool  114 . Alternatively, in some embodiments, the heat source  116  may be configured to heat, but not necessarily melt, the surface  126  of the earth-boring tool component  110 . Heat from the heat source  116  may directly melt the powdered hardfacing material, which may coalesce on the surface  126  of the earth-boring tool component  110 . The CNC processor may determine a tool path for the direct metal deposition tool  114  to apply hardfacing material based on information regarding hardfacing material location included in the electronic representation of the earth-boring tool. 
     In embodiments with hardfacing material comprising a particle-matrix composite material, the particles of the hard material phase may have a higher melting point than the particles of the metal alloy matrix phase. Accordingly, when the direct metal deposition tool  114  is used to apply the particle-matrix composite hardfacing material, the particles of metal alloy matrix material may soften and/or melt under application of heat from the heat source  116  and coalesce into a substantially continuous metal alloy phase on the surface  126  of the earth-boring tool component  110  ( FIG. 2 ). Hard material particles with a higher melting point than the particles of metal alloy matrix material may remain solid during deposition of the hardfacing material, and the deposited hardfacing material may comprise discrete particles of the hard material phase dispersed throughout the continuous metal phase. 
     In some embodiments, machining of the hardfacing material may be necessary to obtain acceptable dimensional tolerances. As hardfacing materials may be difficult to machine using conventional methods, an ultrasonic machine tool (e.g., ultrasonic machine tool  137  ( FIG. 9 )) may be used to machine the hardfacing material. Ultrasonic machining may include using an oscillating tool vibrating at ultrasonic frequencies to remove portions of the hardfacing and/or other materials of the earth-boring tool component  110 . An abrasive slurry may be applied to the area to be machined to aid material removal by the oscillating tool. 
     In some embodiments, the earth-boring tool component  110  ( FIG. 2 ) may remain affixed to the multi-axis positioner  112  ( FIG. 2 ) during ultrasonic machining. For example, an ultrasonic machine tool (not shown) may be operatively (e.g., mechanically and/or electrically) coupled with the multi-axis mill  136  ( FIG. 4 ). In some embodiments, the direct metal deposition tool  114  ( FIG. 2 ) and the machine tool  132  ( FIG. 4 ) may be moved (e.g., translated, pivoted) away from the earth-boring tool component  110 , and the ultrasonic machine tool may be brought into contact with the earth-boring tool component  110  and operated to impart the desired shape and configuration to the earth-boring tool component  110 . The ultrasonic machine tool may be controlled by the CNC processor and may be operated along a tool path generated by the CNC processor based on the electronic representation of the earth-boring tool. 
     Referring now to  FIGS. 5 through 8 , an embodiment of an earth-boring tool is shown during stages of a process according to an embodiment of the disclosure. Specifically,  FIGS. 5 through 8  illustrate a rotary drag bit during various stages of a process according to the disclosure.  FIG. 5  illustrates a shank  138  of an earth-boring tool. The shank  138  may be formed, for example, by machining a section of raw material such as steel bar stock in the multi-axis mill  136 . The shank  138  may include a threaded connection portion  140 , which may conform to industry standards, such as those promulgated by the American Petroleum Institute (API), for attaching the shank  138  to a drill string (not shown). A central opening  142  in the shank  138  may be in fluid communication with one or more fluid passages of the drill string. 
       FIG. 6  illustrates a partially formed rotary drag bit  144  with additional material deposited on the shank  138  ( FIG. 5 ) by a direct metal deposition tool (e.g., direct metal deposition tool  114  ( FIG. 2 )) to form geometric features such as blades  146  and fluid courses  148  between the blades  146 . Cutting element pockets  150  and fluid nozzle receptacles  152  may be formed by one or both of selective deposition of material with the direct metal deposition tool  114  and removal of material with the machine tool  132  ( FIG. 3 ). Internal features such as fluid passageways (not shown) in communication with fluid nozzle receptacles  152  may also be formed by selective deposition and/or machining. 
     Referring now to  FIG. 7 , hardfacing material  154  is applied to areas of the partially formed rotary drag bit  144  that are susceptible to wear. For example, hardfacing material  154  is applied to leading portions of the blades  146  and areas adjacent the cutting element pockets  150 . Although not illustrated in  FIG. 7 , hardfacing material may also be applied to fluid courses  148 , gage surfaces  156 , additional surfaces of the blades  146 , etc. The hardfacing material  154  may be applied by the direct metal deposition tool  114  ( FIG. 2 ) following a tool path generated by the CNC processor, as described above. The hardfacing material  154  may be ultrasonically machined as described above to ensure the cutting element pockets  150  are sized within the desired range based on the design specifications and allowable tolerances. 
       FIG. 8  illustrates a substantially completed rotary drag bit  158 . Cutting elements  160  may be brazed into the cutting element pockets  150  ( FIGS. 6 and 7 ) using heat applied by the heat source  116  ( FIG. 2 ) of the direct metal deposition tool  114  ( FIG. 2 ). For example, the cutting elements  160  may be positioned within the cutting element pockets  150 , and the heat source  116  may be used to heat and melt a metallic braze material. Capillary action may then draw the melted braze material into the space between each of the cutting element pockets  150  and a respective cutting element  160 , and the braze material may solidify and retain the cutting elements  160  within the cutting element pockets  150 . The braze material may be delivered in powdered form through the one or more deposition nozzles  118  ( FIG. 2 ), or may be applied automatically or manually in the form of rods or wire. 
     While  FIGS. 5 through 8  illustrate process stages of a method of forming a rotary drag bit, similar process acts may be used, in the order described, or in different orders or combinations of one or more of the acts described above, to form other earth-boring tools, such as roller-cone bits, hybrid bits, reamer blades, etc. 
       FIGS. 9 and 10  illustrate certain process acts discussed in connection with  FIGS. 7 and 8  in greater detail. In  FIG. 9 , an ultrasonic machine tool  137  is operated (e.g., oscillated at ultrasonic frequencies) to machine hardfacing material  154  disposed on the body of the partially formed rotary drag bit  144  surrounding a cutting element pocket  150 . As described above, the ultrasonic machine tool  137  may be operatively connected to the multi-axis CNC mill  136 , and a tool path of the ultrasonic machine tool  137  may be generated by a CNC processor and at least partially based on an electronic representation of the partially formed rotary drag bit  144 . 
     In  FIG. 10 , a cutting element  160  is placed within the cutting element pocket  150 , and a braze material  159  is heated and melted using a heat source  161  and allowed to flow between surfaces of the cutting element pocket  150  and surfaces of the cutting element  160 . In some embodiments, the heat source  161  may be a heat source of a direct metal deposition tool (e.g., heat source  116  of direct metal deposition tool  114  ( FIG. 2 )). As described above, the braze material  159  may be delivered through, e.g., nozzles  118  ( FIG. 2 ) of the direct metal deposition tool  114 . Upon removal of the heat source  161 , the braze material  159  may be allowed to cool and solidify, thereby retaining the cutting element  160  within the cutting element pocket  150  as shown in  FIG. 10 . 
     In some embodiments, methods according to the disclosure include repairing a worn earth-boring tool. For example, referring now to  FIG. 11 , an earth-boring tool such as a rotary drag bit  162  may become worn (e.g., abraded, eroded) during use. Areas between dashed lines  164  may represent worn portions of the rotary drag bit  162  and may include, without limitation, leading portions of blades  146  and areas adjacent cutting element pockets  150 . Other areas susceptible to wear, although not indicated by dashed lines  164 , may include the fluid courses  148  ( FIG. 7 ), gage surfaces  156  ( FIG. 7 ), etc. 
     To repair the worn rotary drag bit  162 , cutting elements  160  may be removed from cutting element pockets  150  by heating braze material to release each cutting element  160  from each respective cutting element pocket  150 . Worn areas between dashed lines  164  may be built up using the direct metal deposition tool  114  ( FIG. 2 ) and, if necessary, machined to a final profile. In some embodiments, a production tool such as the multi-axis mill  136  ( FIG. 4 ) may be equipped with an optical scanning system (not shown) configured to generate an electronic representation of the actual shape of the worn rotary drag bit  162 . The electronic representation of the actual shape of the worn rotary drag bit  162  may be compared to an electronic representation of a shape of the rotary drag bit  162  according to design specifications. For example, the electronic representation of the actual shape of the worn rotary drag bit  162  and an electronic representation of the design specifications of an associated unworn rotary drag bit may be entered in a processor of the multi-axis mill  136 . The processor may compare the actual shape of the worn rotary drag bit  162  with the design specifications, and may develop a tool path for the direct metal deposition tool  114  to deposit material in appropriate areas to return the worn rotary drag bit  162  to the design specifications. The direct metal deposition tool  114  may apply a metal, metal alloy, hardfacing material, etc. as needed to the worn rotary drag bit  162 . Machining (e.g., milling, ultrasonic machining) as described above may be performed as necessary to the material applied by the direct metal deposition tool  114  to meet the design specifications. The cutting elements  160  may be replaced in the cutting element pockets  150  and brazed within the cutting element pockets  150  as described above. In some embodiments, machining may be performed on the worn areas to clean and/or profile the worn areas (e.g., impart to the worn areas a specified geometric shape) prior to application of material by the direct metal deposition tool  114 . 
       FIG. 12  shows a schematic diagram of a manufacturing system  166  according to the disclosure. The manufacturing system  166  may be or include, for example, the multi-axis CNC mill  136  ( FIG. 4 ). The manufacturing system  166  may include a computer system  168  with memory  170  and a processor  172 . Data containing a geometric representation of an earth-boring tool component (e.g., earth-boring tool component  110  ( FIG. 2 )) may be entered into the memory  170  of the computer system  168 . The computer system  168  may be operatively connected to a CNC multi-axis machine tool  174 , which may include, without limitation, at least one of a multi-axis positioner  176 , a direct metal deposition tool  178 , a machine tool  180 , and an ultrasonic machine tool  182 . Based on the data in the memory  170 , the processor  172  may apply one or more software routines to generate tool paths for one or more of the multi-axis positioner  176 , the direct metal deposition tool  178 , the rotary machine tool  180 , and the ultrasonic machine tool  182  to form an earth-boring tool component  110  as described above. 
     Compared to other methods of forming an earth-boring tool component, direct metal deposition processes may result in significantly less waste of material and smaller manufacturing tolerances, as well as the ability to custom-tailor component shapes and dimensions and to produce a variety of different earth-boring tools in limited numbers, or even a single tool of a particular design. Thus, the disclosed processes may enable cost-effective production of earth-boring tool components from relatively high-cost materials. For example, in some embodiments, the earth-boring tool component  110  ( FIG. 2 ) may comprise so-called “superalloys,” such as nickel-based (e.g., at least about forty percent (40%) by mass nickel) alloys. Reduction of waste due to excessive machining of metallic blanks may enable relatively economical use of costlier materials. 
     Furthermore, provision of the direct metal deposition tool  114  ( FIG. 2 ), machine tool  132  ( FIG. 2 ), and ultrasonic machine tool  137  ( FIG. 9 ) or other tools within a single production station, e.g., multi-axis CNC mill  136  ( FIG. 4 ), may reduce production time and associated cost by eliminating the need to manually or automatically transfer the earth-boring tool component between tools during production. For example, a complete earth-boring tool such as the rotary drag bit  158  ( FIG. 8 ) may be manufactured from start to finish while remaining within the working envelope  134  ( FIG. 4 ) of the multi-axis mill  136  and affixed to the multi-axis positioner  112 . 
     Additional non-limiting example embodiments of the disclosure are set forth below. 
     Embodiment 1 
     A method of forming at least a portion of an earth-boring tool, the method comprising: entering an electronic representation of at least one geometric feature of at least a component of an earth-boring tool in a computer system including memory and a processor, the computer system operatively connected to a multi-axis positioning system, a direct metal deposition tool, and a material removal tool; generating, with the processor, a first tool path for the direct metal deposition tool, the first tool path based at least in part on the electronic representation of the at least one geometric feature of the at least a component of the earth-boring tool; operating the direct metal deposition tool along the first tool path to deposit metal on an earth-boring tool component coupled to the multi-axis positioning system to at least partially form the at least one geometric feature of the earth-boring tool; generating, with the processor, a second tool path for the material removal tool, the second tool path based at least in part on the electronic representation of the at least one geometric feature of the earth-boring tool; and operating the material removal tool along the second tool path to remove at least a portion of the deposited metal from the at least one geometric feature of the at least a component of the earth-boring tool. 
     Embodiment 2 
     The method of Embodiment 1, wherein operating the direct metal deposition tool along the first tool path to deposit metal on the at least a component of the earth-boring tool comprises: applying heat from a heat source to a portion of the at least a component of the earth-boring tool to form a melt pool on a surface of the earth-boring tool component; introducing a powdered metal material into the melt pool by directing a flow of powdered metal material through a deposition nozzle of the direct metal deposition tool; at least partially melting the powdered metal material with heat from one or both of the heat source and heat contained in the melt pool; and solidifying the melt pool and the at least partially melted powdered metal material to form a volume of metal material on the surface of the earth-boring tool component. 
     Embodiment 3 
     The method of Embodiment 2, wherein introducing the powdered metal material into the melt pool comprises introducing a powdered metal material comprising a composition substantially the same as a composition of a metal material of the at least a component of the earth-boring tool. 
     Embodiment 4 
     The method of Embodiment 2, wherein introducing the powdered metal material into the melt pool comprises introducing a powdered metal material comprising a composition different from a composition of a metal material of the at least a component of the earth-boring tool component. 
     Embodiment 5 
     The method of Embodiment 2, wherein introducing the powdered metal material into the melt pool comprises introducing a powdered metal material comprising an alloy composition comprising at least about forty percent (40%) nickel. 
     Embodiment 6 
     The method of any one of Embodiments 1 through 5, wherein operating the direct metal deposition tool along the first tool path to deposit metal on the at least a component of the earth-boring tool comprises: continuously obtaining information related to at least one of temperature of a melt pool formed by a heat source of the direct metal deposition tool and a size of the melt pool formed by the heat source of the direct metal deposition tool; and adjusting a power level of the heat source responsive to the information related to at least one of the temperature of the melt pool and the size of the melt pool. 
     Embodiment 7 
     The method of any one of Embodiments 1 through 6, wherein operating the direct metal deposition tool along the first tool path to deposit metal on the at least a component of the earth-boring tool coupled to the multi-axis positioning system to at least partially form the geometric feature of the earth-boring tool comprises at least one of rotating and translating the at least a component of the earth-boring tool by manipulating the multi-axis positioning system. 
     Embodiment 8 
     The method of any one of Embodiments 1 through 7, wherein operating the material removal tool along the second tool path to remove at least a portion of the deposited metal to form the geometric feature of the earth-boring tool comprises at least one of rotating and translating the at least a component of the earth-boring tool by manipulating the multi-axis positioning system. 
     Embodiment 9 
     The method of any one of Embodiments 1 through 8, wherein operating the material removal tool along the second tool path to remove at least a portion of the deposited metal to form the geometric feature of the at least a component of the earth-boring tool comprises operating a rotary milling tool along the second tool path to remove at least a portion of the deposited metal to form the geometric feature of the at least a component of the earth-boring tool. 
     Embodiment 10 
     The method of any one of Embodiments 1 through 9, wherein operating the direct metal deposition tool along the first tool path to deposit metal on the at least a component of the earth-boring tool to at least partially form the geometric feature of the at least a component of the earth-boring tool comprises depositing a plurality of layers of metal on the at least a component of the earth-boring tool to form a fully-dense geometric feature. 
     Embodiment 11 
     The method of any one of Embodiments 1 through 10, further comprising: generating a third tool path for the direct metal deposition tool; and operating the direct metal deposition tool along the third tool path to apply a hardfacing material to at least a portion of the at least a component of the earth-boring tool. 
     Embodiment 12 
     The method of Embodiment 11, wherein operating the direct metal deposition tool along the third tool path to apply a hardfacing material to at least a portion of the at least a component of the earth-boring tool comprises: introducing a powdered hardfacing material through a nozzle of the direct metal deposition tool to a location on a surface of the at least a component of the earth-boring tool proximate a heat source of the direct metal deposition tool; and applying the powdered hardfacing material to the surface of the at least a component of the earth-boring tool by at least partially melting the powdered hardfacing material with the heat source. 
     Embodiment 13 
     A method of forming a rotary drag bit, the method comprising: entering an electronic representation of a rotary drag bit in a computer system of a multi-axis milling machine, the computer system comprising memory and a processor; affixing a metal blank to a multi-axis positioner of the multi-axis milling machine; removing material from the metal blank by operating a milling tool along a milling tool path determined by the processor of the multi-axis milling machine based at least in part on the electronic representation of the rotary drag bit to form a shank of the rotary drag bit including a threaded portion for connection to a drill string; depositing metal material on the shank of the rotary drag bit by operating a direct metal deposition tool along a first deposition tool path determined by the processor of the multi-axis milling machine based at least in part on the electronic representation of the rotary drag bit to form a geometric feature of the rotary drag bit including at least a portion of a blade on the shank of the rotary drag bit; and depositing a hardfacing material on the at least a portion of the blade of the rotary drag bit by operating a direct metal deposition tool along a hardfacing tool path determined by the processor of the multi-axis milling machine based at least in part on the electronic representation of the rotary drag bit to form at least one hardfaced area on the at least a portion of the blade of the rotary drag bit. 
     Embodiment 14 
     The method of Embodiment 13, further comprising removing at least a portion of the hardfacing material from the at least one hardfaced area to form at least one cutting element pocket in the at least a portion of the blade of the rotary drag bit. 
     Embodiment 15 
     The method of Embodiment 14, wherein removing at least a portion of the hardfacing material from the at least one hardfaced area to form at least one cutting element pocket in the at least a portion of the blade of the rotary drag bit comprises operating an ultrasonic machine tool along an ultrasonic machine tool path determined by the processor of the multi-axis milling machine based at least in part on the electronic representation of the rotary drag bit. 
     Embodiment 16 
     The method of Embodiment 15, further comprising: positioning a cutting element in the cutting element pocket; introducing a braze material to an interface between the cutting element and the cutting element pocket; melting the braze material by applying heat from a heat source to one or both of the braze material and the interface; and solidifying the braze material to retain the cutting element within the cutting element pocket. 
     Embodiment 17 
     The method of Embodiment 16, wherein introducing the braze material to an interface between the cutting element and the cutting element pocket comprises introducing the braze material to an interface between the cutting element and the cutting element pocket by directing a powdered braze material through a deposition nozzle of the direct metal deposition tool. 
     Embodiment 18 
     A method of repairing an earth-boring tool, the method comprising: generating an electronic representation of the shape of a worn earth-boring tool; using a computer system, comparing the electronic representation of the shape of the worn earth-boring tool to an electronic representation of a shape of the earth-boring tool in an unworn state based on design specifications associated with the earth-boring tool to identify worn areas of the earth-boring tool; using a computer system, generating a tool path based on a difference between the compared shape of the worn earth-boring tool and the shape of the earth-boring tool in an unworn state based on the design specifications of the earth-boring tool; and operating a direct metal deposition tool along the tool path to build up worn areas of the worn earth-boring tool to meet the design specifications. 
     Embodiment 19 
     The method of Embodiment 18, wherein generating an electronic representation of the shape of the worn earth-boring tool comprises: positioning the worn earth-boring tool within a working envelope of a multi-axis milling machine; and scanning the shape of the worn earth-boring tool with an optical scanning tool operatively connected to the multi-axis milling machine. 
     Embodiment 20 
     The method of Embodiment 19, wherein operating the direct metal deposition tool along the tool path comprises operating a direct metal deposition tool operatively connected to the multi-axis milling machine while the worn earth-boring tool is positioned within the working envelope of the multi-axis milling machine. 
     Although the foregoing description and accompanying drawings contain many specifics, these are not to be construed as limiting the scope of the disclosure, but merely as describing certain embodiments. Similarly, other embodiments may be devised, which do not depart from the spirit or scope of the disclosure. For example, features described herein with reference to one embodiment also may be provided in others of the embodiments described herein. The scope of the invention is, therefore, indicated and limited only by the appended claims and their legal equivalents. All additions, deletions, and modifications to the disclosed embodiments, which fall within the meaning and scope of the claims, are encompassed by the disclosure.