Earth-boring rotary drill bits including bit bodies comprising reinforced titanium or titanium-based alloy matrix materials, and methods for forming such bits

[0001] The invention relates generally to rotary drill bits, and methods for making such rotary drill bits. In particular, the invention generally relates to rotary drill bits that include a drill body having at least a portion thereof substantially formed of a particulate matrix composite material, and methods of making such rotary drill bits.

BACKGROUND OF THE INVENTION [0002] Rotary drill bits are commonly used for drilling holes or drilling in earth formations. Rotary drill bits cover two basic shapes. One shape is the tapered roller working tip, which typically includes three tapered roller working tips located on the support legs, which are an extension of the drill body. Each conically roller working tip is shaped to spin or rotate on a support leg. On the outer surfaces of each conically roller working tip there are teeth for cutting rock or similar earth formations. Teeth are often covered with abrasive, reinforced ("hardfacing") material. Such materials often include tungsten carbide particles dispersed in a metal alloy matrix material. Alternatively, on the outer surfaces of each conically roller working end there are seats to which reinforced metal cores are attached to form cutting elements. In some cases, these cores contain a high-abrasive material formed on and bonded to a metal substrate. The bite bit can be placed in the hole so that the tapered roller working tips adhere to the earth formation to drill. When the drill is rotated thanks to the pressure applied to the drill, the conically roller tips rotate on the surface of the formation, and the teeth crush the underlying formation. [0003] The second main construction of the rotary drill bit is a milling drill bit (often referred to as a "cutting" drill bit), which typically includes a plurality of cutting elements attached to the face of the bit body area (see, for example, US 2005/0211475, which is considered the closest document from the state of the art, and which reveals a drill of a certain type). Generally, the cutting elements of the milling bit have either a disk shape or a substantially cylindrical shape. A hard, highly abrasive material, such as polycrystalline diamond particles bonded together, can be at the substantially circular end face of each cutting element to form a cutting surface. Such cutting elements are often referred to as PDC ("polycrystalline diamond sinters") milling cutters. Cutting elements can be manufactured separately from the bit body and mounted in recesses formed in the outer surface of the bit body. An adhesive material such as a binder or a braze alloy can be used to attach the cutting elements to the bit body. The cutting bit can be placed in the hole so that the cutting elements will adhere to the earth formation to be drilled. When the drill is rotated, the cutting elements cut or scrape the underlying ground formation surface.

[0004] The rotary drill bit body in any main configuration can be attached conventionally to a hardened steel shaft having an API (American Petroleum Institute) threaded rod for attaching the drill bit to the drill column. The drill column includes a cylindrical tube and equipment segments end to end connected between the drill bit and other drilling equipment on the face. Equipment such as a rotary plate or top drive can be used to rotate the drill column and drill bit in the hole. Alternatively, the bit body can be connected directly to the lower motor drive shaft, which can then be used to rotate the bit.

[0005] The body of the rotary drill bit may be formed of steel. Alternatively, the bit body may be formed of a molecular matrix composite material. Such molecular matrix composite materials typically include tungsten carbide hard particles randomly dispersed in a matrix material of copper or a copper-based alloy (often referred to as the "binder" material). Such drill bit hulls are typically made by dipping a steel forging in a mold with a specific tungsten carbide material, and infiltrating a specific tungsten carbide material with a molten copper or copper-based alloy material. Augers that have drill bodies formed from such a composite matrix molecular material may exhibit increased wear and erosion resistance, but lower strength and hardness compared to drills having steel drill bodies.

[0006] When the conditions and requirements of underground wells have become more stringent, there has been a need in the art for molecular matrix composite materials to be used in drill bit hulls for rotary drill bits that exhibit improved physical properties, and which can be used to improve the operation of earth rotary drill bits .

DISCLOSURE OF THE INVENTION [0007] In one embodiment, the invention includes an earth rotary drill bit for drilling underground formations. The drill bit comprises a bit body comprising a composite matrix material having a plurality of hard particles or dispersed areas in a titanium or titanium based alloy material. The auger further includes at least one cutting structure on the end face of the bit body.

[0008] In another embodiment, the invention includes an earth rotary drill bit comprising a bit body having a plurality of areas having different material compositions. For example, the bit body may include a first area having a first material composition and a second area having a second material composition that differs from the first material composition. The first material composition may comprise a plurality of hard particles or dispersed areas in a titanium or titanium-based alloy material, and the second material composition may include a titanium or titanium-based alloy material. In addition, many cutting structures can be located on the surface of the bit body.

[0009] In another embodiment, the invention includes a method of shaping an earth rotary drill bit. The method includes providing a raw powder component comprising a plurality of hard particles and a plurality of particles comprising titanium or a titanium-based alloy, and at least partially sintered raw powder component to form a bit body containing a composite matrix material. The shank shaped for attachment to the drill column can be attached directly to the bit body.

[0010] The features, benefits, and additional aspects of the invention will become apparent to those skilled in the art after considering the following detailed description with reference to the accompanying drawings.

DESCRIPTION OF THE DRAWINGS [0011] While the description includes claims in particular indicating and explicitly stating what is considered to be the invention, the benefits may be determined from the following description of the invention when read in relation to the accompanying drawings in which

Fig. 1 is a partial cross-sectional side view of an earth rotary drill bit that is a detailed embodiment of the invention and includes a bit body comprising a composite matrix material;

Fig. 2 is a partial cross-sectional side view of another earth-boring rotary drill bit that is a detailed embodiment of the invention and includes a bit body comprising a composite matrix molecular material; Figs. 3A-3J show one example of a method that can be used to form the earth bit body of the rotary drill bit shown in Fig. 2;

FIG. 4A-4C show another example of a method that can be used to form the earth drill bit body of the rotary drill bit shown in Fig. 2;

Fig. 5 is a side view of the shank shown in Fig. 2;

Fig. 8 is a view of Fig.

composite matrix detailed example of devices or representations

Fig. 6 is a cross-sectional view of the shank in Fig. 5 passing along the section line 88 shown;

Fig. 7 is a side cross-sectional view of another bit body that includes the molecular matrix composite material, and which is a detailed embodiment of the invention;

in cross-section of bit body 7, passing along the section line 10-10 shown; and

Fig. 9 is a side cross-sectional view of another bit body that includes the particulate material and which forms embodiments of the invention.

MODE (S) OF IMPLEMENTING THE INVENTION [0012] The presented representations are not concrete views of any particular material, method, but only idealized to describe the invention. In addition, elements that are common in the individual figures may retain the same reference numbers.

[0013] The term "raw" as used means unintended.

[0014] The term "raw bit body" as used herein means a non-sintered structure comprising a plurality of discrete particles joined together through a binder material, the structure having a size and shape that makes it possible to produce a bit body suitable for use in the earth bit from the structure through subsequent manufacturing processes including, but not limited to machining and compaction.

[0015] The term "brown" as used means partially sintered.

[0016] The term "brown bit body" as used means a partially sintered structure comprising a plurality of particles, at least some of which are partially joined together to provide at least partial bonding between adjacent particles, a structure having a size and shape that allows forming a bit body suitable for use in an earth auger from the structure through subsequent manufacturing processes including but not limited to machining and also compaction. The brown bit of the bit may be formed by, for example, partially sintering the raw bit body.

[0017] The term "material composition" as used means the chemical composition and microstructure of the material. In other words, materials having the same chemical composition but different microstructure are considered to have different materials composition.

[0018] The term "sintered" as used herein means the thickening of a specific component including the removal of at least a portion of the pores between the initial particles (in combination with shrinkage) combined with coalescence and bonding between adjacent particles.

[0019] The earth rotary drill bit 10, which is a detailed embodiment of the invention, is shown in Fig. 1. The drill bit 10 includes a bit body 12 comprising a composite matrix material 15 that includes a plurality of hard phase particles or dispersed areas in a titanium matrix material or a titanium based alloy. Hard phase particles or areas are "hard" in the sense that they are substantially harder than the surrounding material with a titanium matrix or titanium-based alloy. In some embodiments, the bit body 12 can mainly include composite matrix material 15, which is described in detail below. The bit body 12 may be attached to a metal shank 20 which may be formed of steel and may include an API 28 threaded shank American Petroleum Institute) for attaching drill bit 10 to the drill column (not shown). The bit body 12 can be secured directly to the shank 20 by, for example, using one or more security elements 46 in combination with brazing and / or welding, as discussed in detail below.

[0020] As shown in Fig. 1, the bit body 12 may include blades or blades 30 that are separated from each other by the slots 32. The internal mud channels 42 may extend between the end face 18 of the bit body 12 and the longitudinal hole 40, which extends through the steel shaft 20 and at least partly through the bit body 12. In some embodiments, nozzle cores (not shown) may be located on the face 18 of the bit body 12 in the internal flushing channels 42.

[0021] Auger 10 may include a plurality of cutting structures on the face 18. As a non-limiting example, many PDC (polycrystalline diamond compact) 34 milling cutters can be located on each blade 30, as shown in Fig. 1. PDC cutters 34 can be positioned along the blade 30 in the recesses 36 formed in the face 18 of the bit body 12, and can be supported from behind by buttresses 38, which can be formed inseparably with the bit body 12.

[0022] The composite matrix material 15 of the bit body 12 may comprise a plurality of hard phase regions or particles dispersed in a titanium matrix material or a titanium based alloy. As a non-limiting example, the hard phase regions may be formed of a plurality of hard particles, and may contain between about 20% and about 60% by volume of the composite matrix material 15, and the matrix material may contain between about 80% and about 40% by volume of the composite material matrix molecular 15.

[0023] In some embodiments, the molecular matrix composite material 15 of the bit body 12 may comprise a metal-ceramic sintered composite material (ie, a "cermet" material). In other words, hard phase areas or particles may contain ceramic material.

[0024] Titanium has two allotropic phases: an α phase with a hexagonal network filled short and a compact cubic β phase. In commercial pure titanium, the α phase is stable at temperatures below about 882 ° C, while the β phase is stable at temperatures between about 882 ° C and the melting point of about 1668 ° C of commercially pure titanium. Various elements are identified as being able to dissolve in titanium to form a solid solution, and as being able to affect the stability of either the α phase or the β phase. Elements that stabilize the α phase are referred to in the art as α stabilizers, while elements that stabilize the β phase are referred to in the art as β stabilizers. For example, aluminum, gallium, oxygen, nitrogen, and carbon were considered α stabilizers, and vanadium, molybdenum, niobium, iron, chromium and nickel were referred to as β stabilizers. Some elements, including tin and zinc, for example, enter solid solution with titanium but do not significantly stabilize either the α phase or the β phase. These elements can be referred to as neutral alloying elements.

[0025] A variety of titanium-based alloys may be prepared so that they include one or more α-stabilizers, one or more β-stabilizers, and / or one or more inert alloying elements. Titanium-based alloys are typically classified as either alpha (α) alloys, convergent alpha (α) alloys, metastable beta (β) alloys, beta (β) alloys, α + β alloys, or titanium clays. Alpha alloys are single-phase alloys that are reinforced with a solid solution by the addition of α stabilizers and / or neutral alloying elements. Convergent alpha alloys include small amounts (generally between about 1 and about 2 atomic percent) of β stabilizers. Convergent alpha alloys may include in the final microstructure mainly the α phase (alpha alloy) with the retained beta phase (beta alloy or metastable beta alloy). Metastable beta alloys generally comprise between about 10 and about 15% of atomic beta stabilizers and mainly at room temperature contain a metastable beta (non-equilibrium) phase. Beta alloys include sufficient amounts of β stabilizers (e.g., about 30 atomic percent) to reproduce a room temperature stable β phase. Α + β alloys contain significant amounts of both the α phase and the β phase (e.g., the α phase and the β phase contain at least about 10% by volume of the alloy). Titanium clays are based on Ti3Al intermetallic compounds (referred to essentially as the α2 phase) and TiAl (generally referred to as the γ phase).

[0026] In some embodiments of the invention, the titanium or titanium-based matrix material may include an α + β titanium alloy. For example, the titanium or titanium-based matrix material may comprise at least about 87.5% by weight titanium, approximately 6.0% by weight aluminum, and approximately 4.0% by weight vanadium (such alloys are usually referred to in the art as Ti-6Al-4V or Ti-64 alloys). Titanium-based alloys may further include at least trace amounts of at least tin, copper, iron, and carbon. In some embodiments, the titanium or titanium-based matrix material may comprise about 89.0% by weight of titanium (e.g., between about 88.0% by weight and about 90.0% by weight), about 6.0% by weight aluminum, and about 4.0% by weight vanadium.

[0027] Table 1 below shows examples of compositions of α + β titanium alloys that can be used as matrix material in the matrix matrix composite material 15 of the bit body 12 shown in Fig. 1.

[0028] In additional embodiments, the titanium or titanium-based matrix material may include beta (β) titanium or metastable beta (β) titanium alloys. Table 2 below shows various examples of the composition of beta (β) titanium alloys that can be used as matrix material in the matrix matrix composite material 15 of the bit body 12 shown in Fig. 1, and Table 3 below shows the different compositions of metastable titanium beta (β) alloys that can be used as matrix material in the matrix matrix composite material 15 of the bit body 12 shown in Fig. 1.

<td colspan="9">TABLE 1 Α + β alloys</td>

<td rowspan="2">Example No.</td><td colspan="8">Approximate Basic% Atomic</td>

<td>Al</td><td>V</td><td>Mo</td><td>Zr</td><td>sn</td><td>si</td><td>fe</td><td>ti</td>

<td> 1</td><td> 6, 0</td><td> 4,0</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>balance</td>

<td> 2</td><td> 6, 0</td><td> 6, 0</td><td>_-</td><td>_-</td><td> 2,0</td><td>_-</td><td> 0,7</td><td>balance</td>

<td> 3</td><td> 4,0</td><td>_-</td><td> 4,0</td><td>_-</td><td> 2,0</td><td> 0,5</td><td>_-</td><td>balance</td>

<td> 4</td><td> 2,25</td><td>_-</td><td> 4,0</td><td>_-</td><td> 11, 0</td><td> 0,2</td><td>_-</td><td>balance</td>

<td> 5</td><td> 6, 0</td><td>_-</td><td> 6, 0</td><td> 4,0</td><td> 2,0</td><td>_-</td><td>_-</td><td>balance</td>

<td colspan="11">TABLE 2</td>

<td></td><td colspan="5">Beta rates</td><td colspan="5">(Β)</td>

<td>Example</td><td></td><td></td><td colspan="5">Approximate Basic</td><td colspan="2">Atomic%</td><td></td>

<td>No.</td><td>Al</td><td>nb</td><td>V</td><td>Mo</td><td>Zr</td><td>sn</td><td>si</td><td>cr</td><td>fe</td><td>ti</td>

<td> 6</td><td> 1,5</td><td>_-</td><td>_-</td><td> 6, 8</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td> 4,5</td><td>balance</td>

<td> 7</td><td> 3, 0</td><td>_-</td><td> 10, 0</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td> 2, 0</td><td>balance</td>

<td> 8</td><td>_-</td><td>_-</td><td>_-</td><td> 11,5</td><td> 6,0</td><td> 4,5</td><td>_-</td><td>_-</td><td>_-</td><td>balance</td>

<td> 9</td><td> 3, 0</td><td> 2, 6</td><td>_-</td><td> 15, 0</td><td>_-</td><td>_-</td><td> 0,2</td><td>_-</td><td>_-</td><td>balance</td>

<td colspan="12">TABLE 3 Metastable beta alloys (β)</td>

<td rowspan="2">Example No.</td><td colspan="11">Approximate Basic% Atomic</td>

<td>Al</td><td>nb</td><td>V</td><td>Mo</td><td>Zr</td><td>sn</td><td>si</td><td>cr</td><td>fe</td><td>IN</td><td>ti</td>

<td> 10</td><td>_-</td><td>_-</td><td> 35, 0</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td> 15, 0</td><td>_-</td><td></td><td>balance</td>

<td> 11</td><td>_-</td><td>_-</td><td>_-</td><td> 40, 0</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td></td><td>balance</td>

<td> 12</td><td>_-</td><td>_-</td><td>_-</td><td> 30, 0</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td></td><td>balance</td>

<td> 13</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td> 30</td><td>balance</td>

[0029] In further embodiments of the invention, at least a portion of the bit body 12 may comprise a titanium or titanium-based matrix material that includes alpha (α) titanium alloys. Table 4 below shows various examples of the composition of alpha (α) titanium alloys (including convergent titanium alpha (α) alloys) that can be used as matrix material in the molecular matrix composite material of at least part of the bit body 12 shown in Fig. 1.

<td colspan="11">TABLE 4 Alpha alloys (α)</td>

<td rowspan="2">Example No.</td><td colspan="10">Approximate Basic% Atomic</td>

<td>Al</td><td>nb</td><td>V</td><td>Mo</td><td>Zr</td><td>sn</td><td>si</td><td>pd</td><td>C</td><td>ti</td>

<td> 14</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td> 0,2</td><td></td><td>balance</td>

<td> 15</td><td> 5, 0</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td> 2,5</td><td>_-</td><td>_-</td><td></td><td>balance</td>

<td> 16</td><td> 8, 0</td><td>_-</td><td> 1,0</td><td> 1,0</td><td>_-</td><td>_-</td><td>_-</td><td>_-</td><td></td><td>oilans</td>

<td> 17</td><td> 6, 0</td><td>_-</td><td>_-</td><td> 2,0</td><td> 4,0</td><td> 2,0</td><td>_-</td><td>_-</td><td></td><td>balance</td>

<td> 18</td><td> 2,25</td><td>_-</td><td>_-</td><td> 1,0</td><td> 5, 0</td><td> 11, 0</td><td>_-</td><td>_-</td><td></td><td>oilans</td>

<td> 19</td><td> 6, 0</td><td>_-</td><td>_-</td><td> 0,5</td><td> 5, 0</td><td>_-</td><td> 0,25</td><td>_-</td><td></td><td>balance</td>

<td> 20</td><td> 6, 0</td><td> 0,7</td><td>_-</td><td> 0,5</td><td> 3,5</td><td> 4,0</td><td> 0,35</td><td>_-</td><td> 0, 06</td><td>balance</td>

[0030] Titanium-based alloys, similar to the examples shown in Tables 1-4, may have an ultimate tensile strength exceeding 1000 megapascals (MPa), a fracture toughness greater than about 100 megapascals 1/2 per square root meter (MPa-m) , and a hardness greater than about 350 on the Vickers hardness scale.

cracking, etc.) to the material [0031] Any titanium-based alloy (in addition, those alloys shown in the examples in Tables 1-4) can be used as the matrix material in the composite matrix material of the 15 drill bit hulls, which are embodiments of the invention ( such as, for example, bit body 12 of bit 10 shown in Fig. 1).

[0032] In some embodiments, at least a portion of the matrix material of the composite material of the molecular matrix 15 can be thermally processed (i.e. heat-treated) to clean or adjust the microstructure of the matrix material and impart one or more desired physical properties (i.e., increased strength, hardness) , resistance to matrix material (and, through the composite molecular matrix 15), as needed or requirements. As a non-limiting example, at least a portion of the material with a titanium or titanium-based alloy can be hardened. By heating the material with a titanium matrix or titanium-based alloy, the fracture toughness of the molecular matrix composite material can be increased or otherwise selectively adjusted. As another example, at least a portion of the titanium or titanium-based alloy material may be treated with solution (ST) or treated with solution and aged (STA). By treating with a solution and aging the material with a titanium matrix or titanium-based alloy, the strength of the composite matrix molecular material can be increased or otherwise selectively adjusted. Due to the relative stability of the hard phase (e.g. ceramic phase), thermal processing techniques can generally be implemented on a titanium matrix material or an alloy based on titanium molecular matrix composite material 15 without adversely affecting the hard phase of the molecular matrix composite material 15 and / or interphase enclosing the area between the hard phase and the metal phase of the composite material molecular matrix 15.

[0033] The hard phase areas of the molecular matrix composite material may include a plurality of at least individual titanium carbide (TiC) particles, titanium diboride (TiB2) particles, and tungsten (W) particles. As a non-limiting example, the hard phase areas may contain between about 20% by about 60% by volume additional volume material and the composite molecular matrix 15. In embodiments, the hard phase areas may contain titanium silicon particles (e.g. Ti5Si3 and / or Ti3Si), which can be formed by, for example, the distribution of silicon nitride particles (Si3N4) during sintering and / or soaking of the composite matrix material 15. In addition, to those skilled in the art, hard phase areas that increase wear resistance composite matrix material 15 and are chemically compatible with the matrix material can be used in the embodiments of the invention.

[0034] In some embodiments, the hard phase areas may have different sizes. Furthermore, in some embodiments, many areas of the hard phase may include or exhibit multi-modal particle size distribution (e.g., bi-modal, tri-modal, tetra-modal, pentamodal, etc.), while in other embodiments, the phase areas hard materials may have a substantially uniform particle size. As a non-limiting example, many areas of the hard phase may include many -20 ASTM (American Society for Testing and Materials) Grids of the hard phase areas. As used herein, the "-20 ASTM Particle Mesh" phase means particles that pass through a standard US ASTM No. 20 screen as defined in ASTM Specification E11-04, which is entitled: Standard Specification for Wire Mesh and Sieve for control purposes.

[0035] Each of the hard phase regions may have a three-dimensional shape that is substantially spherical, rectangular, cubic, pentagonal, hexagonal, etc. In addition, in some embodiments, each hard phase region may comprise a single crystal.

[0036] Continuing with reference to Fig. 1, at least the outer surface of the bit body 12 may be coated with a wear resistant coating (not shown). As a non-limiting example, the wear resistant coating may comprise a titanium nitride layer formed on or in the exposed surfaces of at least a titanium matrix material or titanium alloy alloying composite material matrix 15. The titanium nitride layer may be formed on or in the exposed surfaces of the composite material of the molecular matrix 15 that are shaped for cutting the formation that is drilled through the drill bit 10. In additional embodiments, the wear resistant coating may include titanium diboride or other material formed increasing wear resistance of the composite matrix material 15. In addition, the wear-resistant coating can be strategically placed on different areas of the exposed surfaces of the bit body so as to protect areas of the composite matrix 15 that can be subjected to correspondingly greater wear during drilling. For example, the face 18 of the bit body 12 (e.g. the surfaces of the blade cutting the formation) may be at least partially coated or otherwise have a coating or layer of titanium nitride or other wear-resistant material. In particular, blade surfaces 30 between adjacent cutters 34 and blade surfaces 30 rotatably downstream of cutters 34 may be at least partially coated or otherwise have a coating or layer of titanium nitride or other wear-resistant material.

[0037] During the drilling operation, the drill bit 10 may be positioned at the bottom of the wellbore and rotated when the drilling fluid is pumped to the face 18 of the bit body 12 through the longitudinal bore 40 and internal mud channels 42. When PDC 34 cutters cut or scoop the underlying earth formation, the formation cuttings and detritus are mixed with and suspended in the drilling fluid that passes through the slits on the excavated material 32 and the annular space between the well hole and the drill column to the surface of the earth formation.

[0038] Another earth rotary drill bit 70, which is a detailed embodiment of the invention, is shown in Fig. 2. The rotary drill bit 70 is substantially similar to the rotary drill bit 10 described above and has a bit body 72 that includes a molecular matrix composite material comprising many areas of the hard phase or particles dispersed in a titanium matrix material or titanium based alloy. The bit 70 may also include a shank 20 attached directly to the bit body 72. The shank 20 includes a generally cylindrical outer surface having an outer face and an inner surface. The outer surface of the shank 20 has at least a portion of the longitudinal bore 40 that extends through the drill bit 70. At least one face of the outer surface of the shank 20 can be shaped to attach the shank 20 to the bit body 72. The shank 20 may also include a male and female threaded connection portion API 28 for attaching drill bit 70 to the drill column (not shown). One or more holes 21 may extend through the outer surface of the shank 20. These holes are described in detail below.

[0039] The bit body 72 of the drill bit 70 comprises a plurality of areas having different material compositions. As a non-limiting example, the bit body 72 may include a first area 74 having a first material composition and a second area 76 having a second different material composition. The first area 74 may include longitudinally-lower and lateral-outer areas of the bit body 72 (e.g., the main area of ​​the bit body 72). The first area 74 may include a face 18 of the bit body 72, which may be shaped to have a plurality of cutting elements, such as PDC cutters 34. For example, a plurality of depressions 36 and the abutment 38 may be in or on the face 18 of the bit body 72 to carry and support PDC cutters 34. Furthermore, a plurality of blades 30 and slots 32 may be in the first region 74 of the bit body 72. Second region 76 may include longitudinally-higher and lateral-internal regions of the bit body 72. Longitudinal opening 40 may extend at least partially through the second region 76 of the bit body 72.

[0040] The second area 76 may include at least one surface 78 that is shaped to attach the bit body 72 to the shank 20. As a non-limiting example, at least one groove 16 may be formed in at least one surface 14 of the second area 76, which is shaped to attach the bit body 72 to the shank 20. Each groove 16 may correspond to and be aligned in the hole 21 extending through the outer surface of the shank 20. The securing element 46 can be located in each hole 21 in the shank 20 and in each groove 16. The mechanical negative clearance between the shank 20, the securing element 46 and the bit body 72 can prevent the longitudinal separation of the bit body 72 from the shaft 20, and can prevent rotation of the body bit 72 around the longitudinal axis L70 of the rotary drill bit 70 relative to the shank 20.

[0041] In some embodiments, the bit body 72 of the rotary drill bit 70 may mainly comprise a composite molecular matrix material. In addition, the composition of the molecular matrix composite material may vary selectively in the bit body 72 to provide different areas in the bit body 72 that have different customized physical properties or characteristics.

[0042] In the embodiment shown in Fig. 2, the rotary drill bit 70 includes two securing elements 46. As a non-limiting example, each securing element 46 may include an elongated cylindrical rod that passes through the hole 21 in the shank 20 and the groove 16 formed in surface 78 of the bit body 72. [0043] The mechanical negative clearance between the shank 20, the safety member 46, and the bit body 72 may also form a substantially uniform clearance or gap between the surface of the shank 20 and surfaces 14 in the second region 76 of the bit body 72. As a non-limiting example, a substantially uniform gap between about 50 microns (0.002 inches) and about 150 microns (0.006 inches) may be between the stem 20 and the bit body 72 when the securing elements 46 are located in the holes 21 in the stem 20 and the grooves 16 in bit body 72.

[0044] The brazing material 26 such as, for example, a silver or nickel based metal alloy may be located in a substantially uniform gap between the shank 20 and the surfaces 14 of the second region 76 of the bit body 72. As an alternative to brazing or outside soldering hard, the weld 24 may be around the rotary drill bit 70 on its outer surface along the interface between the bit body 72 and the steel shaft 20. The weld 24 and solder material 26 can additionally be used to further secure the shank 20 to the bit body 72. In this configuration, if the braze material 26 in the substantially uniform gap between the shank 20 and the surfaces 14 in the second region 76 of the bit body 72 and the weld 24 fail when the bit 70 is placed at the bottom of the well during drilling, the security means 46 can prevent longitudinal separation bit body 72 from stem 20, thereby preventing loss of bit body 72 in the wellbore.

[0045] As described above, the first region 74 of the bit body 72 may have a first material composition and the second region 76 of the bit body 72 may have a second, different material composition. The first region 74 may include a composite particle matrix material comprising a plurality of hard phase regions or particles dispersed in a titanium matrix material or a titanium based alloy. Second region 76 of bit body 72 may include metal, metal alloy, or molecular matrix composite material. For example, second region 76 of the bit body 72 may mainly comprise titanium or a titanium-based alloy substantially identical to the matrix material of the molecular matrix composite material in the first region 74. In additional embodiments, both the first region 74 and the second region 76 of the bit body 72 may be essentially formed from and at least mainly comprise a molecular matrix composite material.

[0046] As a non-limiting example, the first region 74 of the bit body 72 may include a plurality of areas or titanium carbide and / or titanium diboride particles dispersed in the matrix material containing one of the α + β alloys shown in Table 1, the beta alloys (β) shown in Table 2, or metastable beta (β) alloys shown in Table 3, and the second region 74 of the bit body 72 may comprise one of the alpha (α) alloys shown in Table 4. In additional embodiments, the second region 74 of the bit body 72 may comprise one of the α + β alloys shown in Table 1, the beta (β) alloys shown in Table 2, or the metastable beta (β) alloys shown in Table 3. In this configuration, the material composition of the first area 74 can be selected to exhibit higher wear and erosion resistance than the material composition of the second area 76. In addition, the material composition of the second area 76 can be selected to increase the machinability of the second area 76 and to allow the bit body 72 to be attached to the shank 20.

[0047] The method in which physical properties can be adjusted to allow machining of the second region 76 may be at least partially dependent on the machining method to be used. For example, if it is desired to machine the second area 76 using conventional stamping, milling, and drilling techniques, the material composition of the second area 76 may be selected to exhibit lower hardness and higher ductility. If it is desired to machine the second region 76 using ultrasound machining techniques, which may include the use of ultrasound induced vibrations delivered to the tool, the composition of the second region 76 may be selected to exhibit higher hardness and lower plasticity.

[0048] In some embodiments, the material composition of the second region 76 can be selected to exhibit a higher fracture toughness than the material composition of the first region 74. In yet further embodiments, the material composition of the second region 76 can be selected to exhibit physical properties, which are adapted to allow bonding of the second area 76. As a non-limiting example, the material composition of the second region 76 may be selected to allow the second region 76 to be bonded to the shank 20. It is understood that different areas of the bit body 72 may have a composition of materials that are selected or adapted to exhibit any desired specific property or physical feature, and the invention is not limited to selecting and creating material compositions for areas to exhibit particular physical properties or features described herein.

[0049] Specific physical properties and characteristics of the composite material (such as hardness) can be determined using appropriate blend principles known in the art. Other physical properties and properties of the composite material may be determined without referring to the rules of mixtures. Such physical properties may include, for example, erosion or wear resistance.

[0050] Figs. 3A-3J show one example of a method that can be used to form the bit body 72 shown in Fig. 2. Generally, the bit body 72 of the rotary drill bit 70 can be formed by separately shaping the first area 74 and the second area 76 like brown structures, gathering the brown structures together to provide a uniform brown bit body, and sintering the single brown bit body to the desired final density.

[0051] Referring to Fig. 3A, the first powder blend 109 may be compressed in the form of either a die 106 using a movable plunger or piston 108. The first powder blend 109 may include a plurality of hard particles and a plurality of particles comprising a titanium or alloy matrix material based on titanium. As a non-limiting example, the first powder blend 109 may include a plurality of titanium carbide and / or titanium diboride particles, as well as a plurality of particles, each comprising α + β alloys shown in Table 1, beta (β) alloys shown in Table 2, or metastable beta alloys (β) shown in Table 3. Optionally, the powder blend 109 may further include additives normally used for pressing powder blends, such as, for example, slip binders during compression and to provide the structural strength of the powder component being pressed, flexibilisers providing binder flexibility, and slip agents or compression aids for reducing intra-partial friction.

[0052] The matrix 106 may include an internal cavity having shaped surfaces and shaped to form at least some surfaces of the second region 74 of the bit body 72. The piston 108 may also have surfaces shaped to form or shape at least some surfaces of the first region 74 of the bit body 72. Cores or displacements 107 may be placed in the matrix 106 and used to determine internal mud channels 42. Additional displacements 107 (not shown) may be used to determine other topographic elements of the first region 74 of the bit body 72.

[0053] A background of about 108 can be introduced into the matrix 106 with great force using mechanical or hydraulic devices or machines to compress the first powder blend 109 in the matrix 106 to form the first raw powder component 110 shown in Fig. 3F. The die 106, piston 108, and first powder mixture 119 can optionally be heated during the pressing process.

[0054] In further methods of compressing the powder mix 109, the powder mix 109 can be pressed at substantially isostatic pressures inside a flexible, hermetically sealed container that is in a pressure chamber.

[0055] The first raw powder component 110 shown in Fig. 3B may comprise a plurality of particles (hard particles of hard material and particles of matrix material) held together by the binder material in powder mix 109 (Fig. 3A) as described above. Certain structural components may be machined in the raw powder component 110 using conventional machining techniques including, for example, turning techniques, milling techniques, and drilling techniques. Hand tools can also be used to manually form or shape components in or on the raw powder component 110. As a non-limiting example, slots for spoil 32 (Fig. 2) can be machined or otherwise formed in the raw powder component 110.

[0056] The first raw powder component 110 shown in Fig. 3B may be at least partially sintered. For example, the raw powder component 110 may be partially sintered to provide the first brown structure 111 shown in Fig. 3C, which has a lower than desired final density. Prior to sintering, the raw powder component 110 may be subjected to slightly elevated temperatures to burn or remove unstable additives that have been added to the powder mix 109 (Fig. 3A) as described above. In addition, the raw powder component 110 may be subjected to a suitable atmosphere adapted to assist in the removal of such additives. Such atmospheres may include, for example, hydrogen at a temperature of about 500 ° C.

[0057] Certain structural components may be machined in the first brown structure 111 using conventional machining techniques including, for example, turning techniques, milling techniques, and drilling techniques. Hand tools can also be used to manually mold or shape components in or on a brown structure 111. As a non-limiting example, the bite cavities 36 may be machined or otherwise formed in the brown structure 111 to form the shaped brown structure 112 shown in Fig. 3D.

[0058] Referring to Fig. 3E, the second powder blend 119 may be compressed in the form of either a die 116 using a movable plunger or piston 118. The second powder blend 119 may include a plurality of particles comprising a material with a titanium matrix or titanium alloy, and optionally may include a plurality of hard particles containing hard material. As a non-limiting example, the second powder blend 119 may include a plurality of particles, each containing the alpha (α) alloys described in Table 4. As an additional example, the second powder blend 119 may include a plurality of particles, each comprising the α + β alloys shown in Table 1, each beta (β) alloys shown in Table 2, or any metastable beta (β) alloys shown in Table 3. In some embodiments, the second powder blend 119 may be substantially similar to the first powder blend 109 described above with reference to Fig. 3A, except for the absence of many hard particles (e.g., titanium carbide and / or titanium diboride) in the second powder blend 119. Optionally, the powder blend 119 may further include additives typically used in pressing powder blends such as, for example, slip agents during compression and to provide the structural strength of the pressed powder component, flexibilisers to provide flexibility to the binders, and slip agents or compression aids to reduce inside partial friction.

[0059] The matrix 116 may include an internal recess having shaped surfaces and shaped to form at least some surfaces of the second bit region 76 of the drill bit 72. The piston 118 may also have shaped surfaces to form or shape at least some surfaces of the second bit 76 of the bit body 72. One or more forging or displacements 117 may be placed in the matrix 116 and used to determine internal mud channels 42. Additional displacements 117 (not shown) may be used to determine other topographic elements of the second region 76 of the bit body 72, if desired.

[0060] The piston 118 can be introduced into the die 116 with great force using mechanical or hydraulic devices or machines to compress the second powder mix 119 in the die 116 to form the second raw powder component 120, shown in Fig. 3F. The die 116, piston 118, and second powder mixture 119 can optionally be heated during the pressing process.

[0061] The second raw powder component 120 shown in Fig. 3F may comprise a plurality of particles (particles of a material with a titanium matrix or titanium-based alloy, and optionally, hard particles containing a hard material) held together by the binder material in the powder mix 119 (Fig. 3E) as described above. Certain structural components may be machined in the raw powder component

120 if necessary, using conventional machining techniques including, for example, turning techniques, milling techniques, and drilling techniques. Hand tools can also be used to manually mold or shape components in or on the raw powder component

120.

[0062] The second raw powder component 120 shown in Fig. 3F may be at least partially sintered. For example, the raw powder component 120 may be partially sintered to provide a second brown structure 121 shown in Fig. 3G, which has a lower than desired final density. Before sintering, the raw powder component 120 may be subjected to slightly elevated temperatures to burn or remove unstable additives that have been added to the powder mix 119 (Fig. 3E) as described above.

[0063] Certain structural components may be machined in the second brown structure 121 as desired using conventional machining techniques including, for example, turning techniques, milling techniques, and drilling techniques. Hand tools can also be used to manually mold or shape components in or on a brown structure 121.

[0064] The brown structure 121 shown in Fig. 3G can then be inserted into the previously formed shaped brown structure 112 shown in Fig. 3D to provide the uniform brown bit body 126 shown in Fig. 3H. The solid brown bit body 126 can then be fully sintered to the desired final density to provide the bit body 72 described above in Fig. 2. When sintering involves compaction and removal of porosity in the structure, the sintered structure will shrink during the sintering process. Linear shrinkage, for example between 10% and 20%, during sintering can occur in the structure. As a result, spatial shrinkage should be considered when selecting tooling (dies, etc.) or machining components in structures that are less than fully sintered.

[0065] In a further method, the raw powder component 120 shown in Fig. 3F may be introduced into or assembled from the raw powder component 110 shown in Fig. 3B to form the raw bit body. The raw bit body can then be machined as needed and sintered to the desired final density. The interfacial surfaces of the raw powder component 110 and the raw powder component 120 may be bonded together during sintering processes. In other methods, the raw bit body may be partially sintered into the brown bit body. Shaping and machining processes can be performed on the brown bit body if desired, and the resulting brown bit body can then be sintered to the desired final density.

[0066] The composition of the material of the first area 74 (and therefore, the composition of the first powder mixture 109 shown in Fig. 3A) and the composition of the material of the second area 76 (and therefore, the composition of the second powder mixture 119 shown in Fig. 3E) can be selected such that showed essentially similar shrinkage during sintering processes.

[0067] The sintering processes described may include conventional sintering in a vacuum oven, sintering in a vacuum oven followed by a conventional isostatic hot pressing process, and sintering followed immediately by isostatic pressing at temperatures close to the sintering temperature (often referred to as sintering temperature) HIP). In addition, the sintering processes described herein may include a sintering phase (sublikwidus). In other words, sintering processes can be carried out at temperatures close to the liquidus line but below this phase line chart of the matrix material. For example, the sintering processes described herein can be carried out using a variety of methods known to the skilled artisan, such as the ROC (Rapid Omnidirectional Compaction) process, the Ceracon ™ process, hot isostatic pressing (HIP), or adaptations of these processes.

[0068] In general, and by way of example only, the sintered raw powder compact using the ROC process comprises pre-sintering the raw powder compact at a relatively low temperature to a sufficient degree to achieve sufficient strength to carry the powder compact. The resulting brown structure is wrapped in a material such as graphite foil to seal the brown structure. The wrapped brown structure is placed in a container that is filled with particles of a hard, polymeric or glass material having a substantially lower melting point than the melting point of the matrix material in the brown structure. The container is heated to the desired sintering temperature, which is above the melting point of the ceramic, polymer or glass particle, but below the liquidus temperature of the matrix material in the brown structure. A heated container with molten ceramic, polymer, or glass material (and a brown structure immersed in them) is placed in a mechanical or hydraulic press, such as a forging press, which is used to apply pressure to molten ceramic or polymer material. The isostatic pressure in the molten ceramic, polymer or glass material allows solidification and sintering of the brown structure at elevated temperatures in the container. Molten ceramic, polymer or glass material transfers pressure and heat to the brown structure. Due to this, the molten ceramic, polymer or glass material acts as a pressure transfer medium through which pressure is applied to the structure during sintering. After releasing pressure and cooling, the sintered structure is then removed from the ceramic, polymer or glass. A more detailed explanation of the ROC process and appropriate devices for carrying it out is disclosed in US patents US Pat. No. 4,094,709. 4233720. 4341557. 4526748. 4547337. 4562990. 4596694. 4597730. 4,656.002 4,744.943 and 5,232,522.

[0069] The Ceracon ™ process, which is similar to the above-mentioned ROC process, can also be adapted for use in the invention to fully sinter brown structures to final density. In the Ceracon ™ process, the brown structure is coated with a ceramic coating, such as alumina, zirconia, or chromium oxide. Other similar, hard, generally inert, protective, removable coatings may also be used. The coating of the brown structure is fully connected by transmitting at least substantially isostatic pressure to the coated brown structure using ceramic particles instead of a fluid medium as in the ROC process. A more detailed explanation of the Ceracon ™ process is found in US Pat. No. 4,499,048.

[0070] As described above, the material composition of the second region 76 of the bit body 72 can be selected to allow machining operations performed on the second region 76, even in a fully sintered condition. After sintering the solid brown bit body 126 shown in Fig. 3H to the desired final density, certain components can be processed in a fully sintered structure to provide the bit body 72, which is shown separately from the shank 20 (Fig. 2) in Fig. 3I. For example, the surfaces 14 of the second bit region 76 of the drill bit 72 may be machined to provide means for attaching the shank 20 (Fig. 2) to the bit body 72. As a non-limiting example, two grooves 16 may be machined in the surface 78 of the second bit body 76 72, as shown in Fig. 3I. Each groove 16 may have, for example, a semi-circular cross-section. In addition, each groove 16 may extend radially around a portion of the second region 76 of the bit body 72, as shown in Fig. 3J. In this configuration, the surface of the second region 76 of the bit body 72 in each groove 16 may have a shape comprising an angular portion of a partial torus. The term "torus" as used herein means a surface formed by a closed curve (such as a circle) revolving around, but not intersecting or not having, an axis in the plane that encloses the closed curve. In other embodiments, the face of the second region 76 of the bit body 72 in each groove 16 may have a shape that substantially forms a partial cylinder. Two grooves 16 may be located on substantially opposite sides of the second region 76 of the bit body 72, as shown in Fig. 3J. [0071] As described, the first region 74 and the second region 76 of the bit body 72 can be separately formed in a brown state and assembled together to form a uniform brown structure, which can then be sintered to the desired final density. In further methods of shaping the bit body 72, the first region 74 may be formed by compressing the first powder mix in the matrix to form the first raw powder component, adding a second powder mix to the same matrix, and compressing the second powder mix in the matrix together with the first powder component of the first area 74 to form a monolithic raw drill body. In addition, the first powder mix and the second powder mix can be contained in a single matrix and simultaneously pressed to form a monolithic raw bit body. The monolithic raw bit body can then be machined as needed and sintered to the desired final density. In further methods, the monolithic raw bit body may be partially sintered into the brown bit body. Shaping and machining processes can be performed on the brown bit body if desired, and the resulting brown bit body can then be sintered to the desired final density. The monolithic raw bit body may be formed in a single matrix using two different pistons, such as piston 108 shown in Fig. 3A and piston 118 shown in Fig. 3E. In addition, additional powder mixes can be provided if desired to form any desired number of areas in the bit body 72 having a material composition.

[0072] Figs. 4A-4C show another method of shaping the bit body 72. Generally, the bit body 72 of the rotary drill bit 70 may be formed by pressing the above-described first powder mix 109 (Fig. 3A) and the second powder mix 119 described above (Fig. 3E) to form a substantially cylindrical monolithic green bit body 130 or ingot as shown in Fig. 4A. As a non-limiting example, the substantially cylindrical monolithic raw bit body 130 may be formed by substantially simultaneous isostatic pressing together of the first powder mix 109 and the second powder mix 119 in a pressure chamber.

[0073] As a non-limiting example, the first powder mix 109 and the second powder mix 119 may be in the container. The container may include a sealed deformable element, such as, for example, a substantially cylindrical bag containing the deformable polymeric material. The container (with the first powder mixture 109 and the second powder mixture 119 contained therein) may be in a pressure chamber. A fluid, such as, for example, water, oil, or gas (such as, for example, air or nitrogen) can be pumped into the pressure chamber using a pump. High fluid pressure causes the surfaces of the deformable element to deform. The pressure can be transferred substantially uniformly to the first powder mixture 109 and the second powder mixture 119. The pressure in the pressure chamber during isostatic pressing may be greater than about 35 megapascals (about 5000 pounds per square inch). In particular, the pressure in the pressure chamber during isostatic pressing may be greater than about 138 megapascals (20,000 pounds per square inch). In further methods, the vacuum may be in the container and a pressure greater than about 0.1 megapascal (about 15 pounds per square inch), may be exerted on the outer surface of the container (through, for example, the atmosphere) and the first powder mix 109 and the second powder mix 119. The isostatic pressing of the first powder mix 109 and the second powder mix 119 can form a substantially cylindrical monolithic raw bit body 130 shown in Fig. 4A, which can be removed from the pressure chamber after pressing.

[0074] The substantially cylindrical monolithic raw bit body 130 shown in Fig. 4A may be machined or shaped as desired. As a non-limiting example, the outer diameter of the end of the substantially cylindrical monolithic green bit body 130 can be reduced to form the shaped monolithic green bit body 132 shown in Fig. 4B. For example, the substantially cylindrical monolithic raw bit body 130 can be rotated on a lathe to form a shaped monolithic raw bit body 132. Additional machining or shaping of the substantially cylindrical monolithic raw bit body 130 can, if desired or when desired, be performed. In other methods, the substantially cylindrical monolithic raw bit body 130 may be rotated on a lathe to ensure that the monolithic raw bit body 130 is substantially cylindrical without reducing the outer diameter of its end or otherwise changing the shape of the monolithic raw bit body 130.

[0075] The shaped monolithic raw bit body 132 shown in Fig. 4B may then be partially sintered to provide the brown bit body 134 shown in Fig. 4C. The brown bit body 134 can then be machined, when required, to form a structure substantially identical to the above-described shaped solid brown bit body 126 shown in Fig. 3H. As a non-limiting example, the longitudinal hole 40 and internal mud channels 42 (Fig. 3H) may be formed in the brown bit body 134 (Fig. 4C) by, for example, using a machining process. Many wells 36 for PDC cutters 34 can also be machined in the brown bit body 134 (Fig. 4C). In addition, at least one face 78 (Fig. 3H), which is shaped to attach the bit body 72 to the shank 20 can be machined in the brown bit body 134 (Fig. 4C).

[0076] When the brown bit body 134 shown in Fig. 4C has been machined to form a structure substantially identical to the shaped solid brown bit body 126 shown in Fig. 3H, the structure can further be sintered to the desired final density and certain additional components can be machined fully sintered structure as required to provide bit body 72 shown in Fig. 3I as described above.

[0077] In additional embodiments, the bit body 72 may be formed using a conventional infiltration process. For example, a plurality of particles each containing hard material (e.g., titanium carbide, titanium diboride, etc.) may be placed in the cavity of the graphite mold (or mold formed of any refractory material) that is shaped to form the first region 74 of the bit body. Forging or displacement elements (which may contain ceramic components, graphite components, or densified components of sand coated with resin) can be placed in the mold and used to determine internal channels 42, cavities 36, slits for spoil 32, and other external or internal topographic elements auger body 12. Furthermore, the forging or displacement element may be located in the cavity region of the graphite mold that is shaped to form the second region of the bit body 72. [0078] The material with a titanium matrix or titanium-based alloy can be melted, poured into the cavity, and infiltrate particles containing hard material to form the first region 74 of the bit body 72. The mold and partially formed bit body may be allowed to cool to solidify the molten matrix material. The forging or displacement element previously positioned in the region of the graphite mold cavity shaped to form the second region of the bit body 72 may be removed from the mold cavity, and another forging or displacement element may be located in the region of the graphite mold cavity corresponding to the inner longitudinal opening 40. Second bit body 76 region 76 may then be formed in a manner substantially similar to that described above with respect to first region 74. If second bit body 76 region 76 includes titanium or a titanium-based alloy material without any hard phase areas or particles, titanium or alloy material based on titanium, it can simply be melted and poured into the mold cavity without pre-filling the mold cavity with hard particles.

[0079] After cooling the bit body 72, the bit body 72 can be removed from the mold and all displacements can be removed from the bit body 72. When removing the bit body 72, it may be required to destroy the graphite mold.

[0080] At least a portion of the bit body 72 shown in Fig. 3I may be subjected to one or more heat treatment processes (i.e., heat quenching) to clean or adjust the microstructure of the bit body material 72 and to give one or more desirable physical properties (i.e. increased strength, hardness, fracture toughness, etc.) of bit body 72 material, if desired or desired. As a non-limiting example, at least part of the bit body 72 may be hardened to increase or otherwise adapt the crack resistance of the bit body 72. In general, titanium alloys may be hardened to increase crack resistance, plasticity at room temperature, spatial and thermal stability, and creep resistance. The time and temperature for any quenching process depends on the particular titanium alloy that is hardened and the microstructure and the desired physical properties to be given to the material, and the general procedures for determining the appropriate time and tempering temperature for imparting such microstructure and the physical properties of the material basic knowledge of specialists in the field.

[0081] As another example, at least a portion of the bit body 72 comprising α + β alloys, beta alloys (β), or metastable beta alloys (β) can be treated with solution (ST) or treated with solution and aged (STA) to clean or adapt the microstructure of the bit body 72 material and give one or more desirable physical properties (e.g., increased strength) to the bit body material 72, if desired or when desired. Basically, titanium-based alloys can be treated with a solution by heating the titanium-based alloy to a solution temperature of about (slightly below or above) a beta transus temperature (e.g., between about 690 ° C and about 1060 ° C) for between about fifteen minutes to about two hours to allow phase equalization at solution temperature. The material is then hardened (i.e. rapidly cooled) from solution temperature to room temperature using air and / or water. During quenching, at least some areas containing a higher beta (β) temperature phase may be trapped or retained in the microstructure of the titanium-based alloy in a metastable, unbalanced state.

in aging, at least some of these non-equilibrium phases can decompose into a stable, equilibrium phase. The treated titanium-based alloys are aged at temperatures below the solution temperature, generally between about 390 ° C and about 760 ° C, for a time range of about two hours to several hundred hours. Again, the time and temperature for the solution treatment and / or aging process depends on the specified

When subjecting metastable, titanium alloy that is machined and microstructure and physical properties to be given to the material, and general procedures for determining the appropriate machining time and temperature to give such microstructure and physical properties to the material, which are within the general knowledge of specialists in the field.

[0082] As titanium alloys are generally susceptible to oxidation, any heat treatment process can be carried out in a controlled inert environment.

[0083] Optionally, at least part of the outer surface of the bit body 72 may be nitrided before or after the bit body 72 has been thermally treated, if necessary or desired, this may increase the hardness and / or wear resistance of the composite matrix material 15 on exposed, engaging surfaces of the bit body 72. As a non-limiting example, the bit body 72 may be nitrided using a plasma nitriding process in a plasma chamber. The process temperature for plasma nitriding of titanium and its alloys varies from about 425 ° C to about 725 ° C, the optimal temperature depends on the specific material composition and other parameters. Any titanium oxide at or on the outside of the bit body 72 may be removed prior to nitriding. As a non-limiting example, the outer surface of bit body 72 may be nitrided in an atmosphere containing a mixture of nitrogen and hydrogen (e.g., between about 20% and about 60% nitrogen by volume) at pressures ranging from, for example, several millipascals to several kilopascals or more, and in a time range from, for example, several minutes to several hours or more.

[0084] In further methods, selected areas or exposed areas that engage the surface formation of the bit body 72 may be nitrided using a laser nitriding process. As a non-limiting example, the outer contact surface of the bit body 72 may be nitrided by irradiating the surface of the bit body 72 with intense pulsed ion beam (IPIB) radiation at room temperature, which allows the physical properties of the bulk material to remain substantially unchanged. Such irradiation can be carried out, for example, in a nitrogen-containing atmosphere under vacuum (e.g. at a pressure below about 0.02 pascal).

[0085] Again, with reference to Fig. 2, the shank 20 can be attached to the bit body 72 by supplying brazing material 26 such as, for example, a silver-based or nickel-based metal alloy in the gap between the shank 20 and surface 14 in the second area 76 of the bit body 72. As an alternative to soldering, or in addition to welding, the weld 24 can be around the rotary drill bit 70 on the outer contact surface along the contact surface between the bit body 72 and the steel shaft 20. Solder material 26 and the weld 24 can be used to attach shaft 20 to drill bit body.

[0086] In additional methods, constructions or elements that provide mechanical negative clearance can additionally be used for or instead of solder material 26 and weld 24 to attach shank 20 to bit body 72. An example of such a method of fastening shank 20 to bit body 72 it is described below with reference to Fig. 2 and Figs. 5-7. With reference to Fig. 5, in the stem 20 there may be two holes 21 as described above with reference to Fig. 2. Each hole 21 may have a size and shape formed to receive the security element 46 (Fig. 2). As a non-limiting example, each hole 21 may have a substantially cylindrical cross-section and may extend through the shaft 20 along the axis L21, as shown in Fig. 6. The arrangement and direction of each hole 21 in the shank 20 may be such that each axis L21 is in a plane that is substantially perpendicular to the longitudinal axis L70 of the drill bit 70, but does not intersect the longitudinal axis L70 of the drill bit 70.

[0087] When the securing element 46 is inserted through the hole 21 of the stem 20 and the groove 16, the securing element 46 may adhere to the contact surface of the second region 76 of the bit body 72 in the groove 16 along the contact line if the groove 16 has a shape comprising an angular portion of a partial torus, as shown in Figs. 3I and 3J. If the groove 16 has a shape that essentially forms a partial cylinder, however, the safety element 46 may adhere to the area on the interface of the second region 76 of the bit body in the groove 16.

[0088] In some embodiments, each security element 46 may be attached to the shaft 20. As a non-limiting example, if each security element 46 includes a longitudinal cylindrical rod as shown in Fig. 2, the ends of each security element 46 may be welded to the shaft. 20 along the contact surface between the end of each security element 46 and the shank 20. In additional embodiments, brazing material (not shown) may be between the ends of each security element 46 and shank 20. In yet further embodiments, threads may be on the outer contact surface of each end of each security element 46, and corresponding threads may be present. on the surface of the stem 20 in the holes

21.

[0089] Again with reference to Fig. 2, brazing material such as, for example, a silver or nickel based metal alloy may be located in a substantially uniform gap between the stem 20 and the surface 14 in the second region 76 of the bit body 72. Weld 24 may be around the rotary drill bit 70 on the outer contact surface along the contact surface between the bit body 72 and the steel shank 20. The weld 24 and brazing material 26 may also be used to attach the shank 20 to the bit body 72. In this configuration, if the brazing material 26 in the substantially uniform gap between the shank 20 and the surface 14 in the second region 76 of the bit body 72 and the weld 24 are damaged when the bit 70 is placed at the bottom of the well during drilling, the security means 46 can prevent longitudinal separation bit body 72 from stem 20, thereby preventing loss of bit body 72 in the wellbore.

[0090] In additional methods of fastening the shank 20 to the bit body 72, only one securing element 46 or more than two securing elements 46 can be used to attach the shaft 20 to the bit body 72. In further embodiments, there may be a threaded connection between the other area 76 of bit body 72 and shank 20. Since the material composition of the second region 76 of the bit body 72 can be selected to allow its machining even in a fully sintered condition, threads having specific diameters can be machined on the second region 76 of the bit body 72. In additional embodiments, the interface between the shank 20 and bit body 72 may be substantially tapered. In addition, a contraction fit or press fit may occur between the shank 20 and the bit body 72.

[0091] Particle matrix composite materials utilized in drill bit hulls or earth-boring rotary drill bits typically include particles or areas of tungsten carbide dispersed in matrix materials based on copper alloys. Copper alloys generally show a coefficient of linear thermal expansion (CTE) between about 16.0 μm / m ° C and 22.0 μm / m ° C (at room temperature), tungsten carbide generally has a linear thermal expansion coefficient between about 4.0 μm / m ° C and 7.5 μm / m ° C, and conventional molecular matrix composite materials containing tungsten carbide particles or regions dispersed in a copper alloy matrix material generally exhibit a linear thermal expansion coefficient of about 12.0 μm / m ° C (as estimated using the Turner equation). However, graphite matrices and forging (or displacement) elements used in conventional infiltration methods generally show a coefficient of linear thermal expansion between about 1.2 μη ^^ and 8.2 ^ / m ° C. As a result of the disproportion in the coefficient of thermal expansion between graphite matrices and conventional molecular matrix composite materials, conventional bit bodies of the molecular matrix composite material formed using infiltration processes may have significant residual stresses in the particle matrix composite material after formation of the drill bit hulls. These stresses can be significant in areas of the bit body adjacent to the graphite matrix and / or the forging elements (or displacements), and can lead to premature cracks in these areas (e.g., areas on or adjacent to the blade 30 and / or spoil gap 32 ( Fig. 2), areas adjacent to the wells of the rods 36 (Fig. 2), areas adjacent to the internal mud channels 42, etc.). Such cracks can lead to premature failure of the rotary drill bit.

[0092] Materials of titanium and titanium-based alloys generally have a coefficient of linear thermal expansion between about 7.6 μm / m ° C and 9.8 μη / η ° Ο, while titanium carbide has a coefficient of linear thermal expansion of about 7.4 μm / m ° C and titanium dioxide have a coefficient of linear thermal expansion of about 8.2 μη / η ° Ο. Due to this, molecular matrix composite materials that include a plurality of titanium carbide and / or titanium diboride particles dispersed in a titanium matrix material or a titanium based alloy can exhibit a coefficient of linear thermal expansion between about

7.5 μm / m ° C a 9.5 μη / η ° Ο. As a result, the described molecular matrix composite materials may exhibit a coefficient of linear thermal expansion that is substantially equal to or less than about double the coefficient of linear thermal expansion of a graphite matrix (or matrix containing any other refractory material) in which the bit body can be cast from using such molecular matrix composite materials. Thus, by using the described molecular matrix composite materials to manufacture drill bit hulls for rotary drill bits, the residual stress arising in the drill bit hulls due to a mismatch between the coefficient of thermal expansion between the materials and the matrices can be reduced or eliminated, and the operation of rotary drill bits containing such drill bits can be improved with respect to known drills.

[0093] In addition, titanium and titanium-based alloys may exhibit increased corrosion resistance relative to conventional copper and copper-based alloys, which are used in molecular matrix composite materials for conventional drill bit hull drill bits, which may further improve the performance of rotary drill bits comprising a drill body formed from the materials described with respect to conventional earth-boring rotary drill bits. [0094] The bit body 12 described above and shown in Fig. 1 may be formed using methods essentially similar to those described in relation to the bit body 72 shown in Fig. 2 (including methods of infiltration as well as ways of matching and sintering powders).

[0095] In the embodiment shown in Fig. 2, the bit body 72 includes two different areas having a material composition with a recognizable boundary or contact surface between them. In additional embodiments, the material composition of the bit body 72 can be constantly varied between areas in the bit body 72 so that no boundaries or contact surfaces between the areas will be immediately recognizable. In additional embodiments, the bit body 72 may include more than two areas having a material composition, and the spatial arrangement of different areas having the material composition in the bit body 72 may vary.

[0096] Fig. 7 shows an additional bit body 150, which is a detailed embodiment of the invention. The bit body 150 includes the first area 152 and the second area 154. As best seen in the cross-sectional view of the bit body 150 shown in Fig. 8, the contact surface between the first area 152 and the second area 154 may generally mimic the topography of the inner contact surface of the first area 152. For example, the contact surface may include a plurality of longitudinally extending edges 156 and recesses 158 corresponding to blades 30 and slots 32 that may be on and in the internal contact surface of the bit body 150. In such a configuration, the blades 30 on the bit body 150 may be less prone to cracking when torque is applied to the drill bit containing the bit body 150 during drilling.

[0097] Fig. 9 shows another bit body 160 which is a detailed embodiment of the invention. The bit body 160 further includes a first area 162 and a second area 164. The first area 162 may include longitudinally the lower area of ​​the bit body 160, and the second area 164 may longitudinally include the upper area of ​​the bit body 160. In addition, the inner contact surface between the first area 162 and the second area 164 may include a plurality of radially extending edges and depressions (not shown) which may cause the bit body 160 to be less susceptible to cracking along the contact surface when during drilling is applied to the bit, including bit body 160, torque.

[0098] Because the details of the invention are described herein with reference to embodiments of concentric earth rotary drills that include fixed knives, other types of earth drilling tools, such as, for example, core drills, eccentric drill bits, double centered drilling bits, dilators, devices shredding, drill bits, harrows, drills with a tapered roller working end, and other such prior art constructions may form the details of the invention and may be obtained by methods based on the details of the invention. Thus, the term "drill bits" as used herein includes and includes all of the above constructions.

[0099] Although the invention has been described with reference to certain preferred embodiments, those skilled in the art will understand that it is not so limited. On the contrary, many additions, deletions and modifications of the preferred embodiments can be made without departing from the scope of the invention as claimed below. In addition, the elements of one embodiment may be combined with the elements of another embodiment while being within the scope of the invention as anticipated by the inventors. In addition, the invention is applicable to drill bits and core drills having different drill profiles as well as types of cutting tools.

20425 / EP / 10

EP 2 089 604 B1