Shaped cutter with alignment structure for drill bit and assembly method thereof

Abstract

Disclosed is a drill bit for cutting formation comprises a bit body, a plurality of cutters, a plurality of blades with pockets to accommodate the cutters respectively. Each of the plurality of cutters has at least one alignment structure to align with at least one counter-alignment structure on each of the pockets to locate the rotary orientation between each of the plurality of cutters and each of the corresponding pockets.

Claims

1. A drill bit for cutting earth formations, comprising a bit body; a plurality of cutters having cutter ridges; a plurality of blades with pockets to accommodate the plurality of cutters respectively; wherein each of the plurality of cutters has at least one alignment structure to align with at least one counter alignment structure on each of the pockets to locate the rotary orientation between each of the plurality of cutters and each of the corresponding pockets; and wherein one of the at least one alignment structure aligns with one of the cutter ridges, wherein a line parallel to the cutter longitudinal axis coincides with the one of the cutter ridges and passes through the one of the at least one alignment structure.

2. The drill bit of claim 1, wherein the cutters are PDC cutters.

3. The drill bit of claim 2, wherein the cutters are shaped cutters.

4. The drill bit of claim 3, wherein the shaped cutters are axially asymmetrical.

5. The drill bit of claim 4, wherein each blade profile of the plurality of blades, a position and orientation of each of the pockets relative to the blade profile and the rotary orientation of each of the shaped cutter relative to the accommodating pocket are determined such that each of the shaped cutters has a desired orientation of cutting face with respect to the earth formations.

6. The drill bit of claim 1, wherein the alignment structure is a protrusion at the bottom of a substrate of the cutter.

7. The drill bit of claim 6, wherein the protrusion is formed integrally with the substrate.

8. The drill bit of claim 7, wherein the protrusion is formed by cutting the bottom of the substrate.

9. The drill bit of claim 1, wherein the alignment structure is a depression at the bottom of a substrate of the cutter.

10. The drill bit of claim 9, wherein the depression is formed integrally with the substrate.

11. The drill bit of claim 10, wherein the depression is formed by cutting the bottom of the substrate.

12. The drill bit of claim 1, wherein the number of the at least one alignment structure is three.

13. The drill bit of claim 12, wherein the three alignment structures are distributed asymmetrically along the circumference of the bottom of the substrate of the cutter.

14. A method to arrange a shaped cutter to a drill bit, comprising: configuring a bit body coupled to a plurality of blades; configuring a shaped cutter having at least one cutter ridge; determining a desired orientation of cutting face of the shaped cutter with respect to a formation based on the performance of the cutter; determining a blade profile of the blade, the position and orientation of a pocket relative to the blade profile and rotary orientation of the shaped cutter relative to the pocket; fabricating at least one alignment structure on the bottom of the shaped cutter, fabricating at least one slot on the bottom of the pocket, such that the shaped cutter has a determined rotary orientation relative to the pocket when the at least one slot fits the at least one alignment structure; wherein one of the at least one alignment structure aligns with one of the at least one cutter ridge, wherein a line parallel to the cutter longitudinal axis coincides with the one of the cutter ridges and passes through the one of the at least one alignment structure.

15. The method of claim 14, wherein the performance of the cutter is WOB.

16. The method of claim 14, wherein the performance of the cutter is ROP.

17. The method of claim 14, wherein fabricating the at least one alignment structure on the bottom of the shaped cutter is to cut the bottom of the substrate of the shaped cutter using laser cut or electrical discharge machining.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order that the manner in which the above-recited and other enhancements and objects of the disclosure are obtained, a more particular description of the disclosure briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through the use of the accompanying drawings in which:

(2) FIG. 1 is a sectional view of a prior art drill bit;

(3) FIG. 2 is a perspective view of a prior art cutter with plane working surface;

(4) FIG. 3 is a schematic view of a prior art cutter with plane working surface engaged with a formation to illustrate back rake angle;

(5) FIG. 4 is a perspective view of a prior art shaped cutter;

(6) FIG. 5 is a partial sectional view of a prior art cutter with plane working surface engaged with a formation in a cutting operation;

(7) FIG. 6 is a perspective view of a shaped cutter in accordance with an embodiment of the present disclosure;

(8) FIG. 7 is a perspective view of a shaped cutter in FIG. 6 with the bottom upward;

(9) FIG. 8 is a perspective view of an embodiment of a shaped cutter;

(10) FIG. 9 is s a perspective view of an embodiment of a shaped cutter;

(11) FIG. 10 is a partial sectional view of a drill bit cutter in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

(12) The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present disclosure only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the disclosure. In this regard, no attempt is made to show structural details of the disclosure in more detail than is necessary for the fundamental understanding of the disclosure, the description taken with the drawings making apparent to those skilled in the art how the several forms of the disclosure may be embodied in practice.

(13) The following definitions and explanations are meant and intended to be controlling in any future construction unless clearly and unambiguously modified in the following examples or when application of the meaning renders any construction meaningless or essentially meaningless. In cases where the construction of the term would render it meaningless or essentially meaningless, the definition should be taken from Webster's Dictionary 3.sup.rd Edition.

(14) The present disclosure relates to shaped cutters that provide advantages when compared to prior art cutters. In particular, embodiments of the present disclosure relate to shaped cutters that have alignment structure in order to improve cutter performance. As a result of the alignment structure, embodiments of the present invention may provide desired orientation of cutting face with respect to the formation when compared with prior art cutters.

(15) Embodiments of the present disclosure relate to cutters having a substrate or support stud, which in some embodiments may be made of cemented carbide, for example tungsten carbide, and an ultra-hard cutting portion or “table” made of a polycrystalline diamond material or a polycrystal line boron nitride material deposited onto or otherwise bonded to the substrate at an interface surface.

(16) FIG. 6 illustrates an embodiment of a shaped cutter 260 of the present disclosure. The shaped cutter has a cylindrical cemented carbide substrate 266 and a cutting portion 267. The substrate has a central axis 269 and a generally cylindrical side surface 270. Cutting portion include a shaped working surface. The shaped working surface include three bevels 262a, 262b and 262c extending radically outwardly to the cutting edge, three ridges 263a, 263b, 263c are separated by the three bevels. Three ridges meet the chamfer and form preferred cutting points 273. The bevels comprise planar surfaces or facets each at an obtuse angle relative to a central axis 269 of the cutter, such that three protrude areas are formed the ridges. A chamfer, indicated by reference numeral 264 in FIG. 6, is typically formed on a portion of the outer edge of the cutting portion of shaped cutter. Chamfers generally comprise an angled section, conventionally at a 45° angle to the cutting face of cutting portion, on a portion of the front outer radius of the cutting portion. The chamfers are added to the cutter to reduce localized stresses on the cutting portion 267 when a cutter is first cutting formation material.

(17) The process for making a cutter may employ a body of cemented tungsten carbide as the substrate where the tungsten carbide particles are cemented together with cobalt. The carbide body is placed adjacent to a layer of ultra-hard material particles Such as diamond or cubic boron nitride particles and the combination is subjected to high temperature at a pressure where the ultrahard material particles are thermodynamically stable. This results in recrystallization and formation of a polycrystalline ultra-hard material layer, Such as a polycrystalline diamond or polycrystalline cubic boron nitride layer, directly onto the upper surface of the cemented tungsten carbide substrate 266.

(18) As can be seen from FIG. 6, the cutter is axially asymmetrical. In order to control the rotation of the cutter in a pocket, the cutter provides at least one alignment structure 272 at the bottom end of the substrate 266. In some embodiments, the alignment structure 272 can be a protrusion at the bottom of the substrate 266. Referring to FIG. 7, in one embodiment, the alignment structure 272 can be a protrusion along the outer edge of the substrate 266 and be formed integrally within the substrate 266. The alignment structure 272 can be fabricated to cut the bottom of the substrate 266 using laser cut or electrical discharge machining (EDM) cuts to create protrusions. The alignment structure 272 can be located at any place at the bottom of the substrate 266 except the center of the substrate 266. In one embodiment, the alignment structure 272 aligns at least with one cutter ridge. Referring to FIG. 6, a line 280 coincide with a ridge 263c and align the center of the alignment structure 272.

(19) EDM is a kind of method to process the size of materials which employs the corrosion phenomena produced by spark discharge. In a low voltage range, EDM performs spark discharge in liquid medium. EDM is a self-excited discharge, which is characterized as follows: before discharge, there is a higher voltage between two electrodes used in spark discharge, when the two electrodes are close, the dielectric between them is broken down, spark discharge will be generated. In the process of the break down, the resistance between the two electrodes abruptly decreases, the voltage between the two electrodes is thus lowered abruptly. Spark channel must be promptly extinguished after maintaining a fleeting time, in order to maintain a “cold pole” feature of the spark discharge, that is, there's not enough time to transmit the thermal energy produced by the channel energy to the depth of the electrode. The channel energy can corrode the electrode partially. When processing diamond composite sheet with EDM, since the residual catalyst metal cobalt produced in the process sintering diamond composite sheet having conductivity, the diamond composite sheet can be used as electrodes in the EDM, and thus can be machined by EDM.

(20) EDM can avoid the error caused by the inability to accurately control the diamond shrinkage during sintering process. EDM technology can effectively control the machining accuracy, and can reduce the damage to the substrate 266 during the machining process. The alignment structure 272 formed by electric spark machining have characteristics of high processing precision, low cost, small damage to the substrate 266 and so on. When processing the alignment structure 272, one can prefabricate plane bottom type substrate 266 at first, and then perform precision machining through EDM. The whole process cost can be reduced, the machining accuracy is satisfied, and the damage to the surface of the diamond composite layer is minimal. There is no need to develop sintering cavity assembly for the diamond composite layer, thus having good flexibility and low-cost. Referring to FIG. 7, a virtual plane 285 is flush with both the bottom of the substrate 266 and the bottom of the alignment structure 272, which means that the alignment structure 272 is fabricated from a plane bottom type substrate.

(21) FIG. 8 illustrates an embodiment of another type of shaped cutter 560 of the present disclosure. The shaped cutter has a cylindrical cemented carbide substrate 566 and a top ultra-hard layer 568. The substrate has a generally cylindrical side surface 570. The ultra-hard layer includes a shaped working surface 567. The cutter 560 includes two side facets 569. The side facets 569 extend obliquely inward from the substrate 566 to the top surface 567. Thus, they can be regarded as portions of the substrate 566 and ultra-hard layer 568. The side facets 569 are generally planar. A partial circular section 563 is formed between the two side facets 569 and becomes the cutting edge. The center point 571 of the cutting edge becomes the preferred cutting point of this type of shaped cutter.

(22) FIG. 9 illustrates an embodiment of yet another type of shaped cutter 660 of the present disclosure. The shaped cutter has a cylindrical cemented carbide substrate 666 and a top ultra-hard layer 668. The substrate has a generally cylindrical side surface 670. The ultra-hard layer includes a concave working surface 667. The edge 673 of the concave surface 667 meets the cylindrical side surface 670 to form cutting edge 663. The center point 674 of the cutting edge 663 is the preferred cutting point for this type of shaped cutter 660.

(23) FIG. 10 illustrates a section of a blade 400 of a bit according to an embodiment of present disclosure. Two shaped cutters 260 described above are separately secured into Two pockets 415 along the profile 413 at different position. The three shaped cutters have different orientations relative to the profile 413, embodiments of the present disclosure may provide desired orientation of cutting face with respect to the formation. The desired orientation of the cutting face can be back rake angle, side rake angle, etc. as described in U.S. Pat. No. 7,441,612 to Bala, which is incorporated herein by reference.

(24) The blade profile 413, the position and orientation of the pockets 415 relative to the blade 400 and orientations of the shaped cutter 260 relative to the pockets 415 can determine the orientation of cutting face with respect to the formation. As described above, because the cutter 260 is not axially symmetrical, the orientation of cutting face with respect to the formation will varied by rotating the shaped cutter 260 in the pockets 415 even if the position and orientation of the pockets 415 relative to the blade 400 is determined. In order to determine the orientation of cutting face with respect to the formation, at least one counter alignment structure 412 is provided on the bottom of the pocket to fit at least an alignment structure 272 of the shaped cutter 260 to align the shaped cutter 260 such that the shaped cutter 260 has a desired orientation of cutting face with respect to the formation. In some embodiments, the counter alignment structure 412 is a depression at the bottom of a substrate of the cutter and the depression is formed integrally with the substrate. In some embodiments, the depression is formed by cutting the bottom of the substrate. In an embodiment, the counter alignment structure 412 is a slot.

(25) The number of the counter alignment structures 412 in the pocket can be arbitrary and equals to the number of alignment structures 272 on the shaped cutter 260. The slots are distributed asymmetrically along the circumference of the bottom of the pockets 415, and alignment structures 272 are located on the corresponding position at the bottom of the shaped cutter 260 such that the shaped cutter 260 has a determined rotary orientation relative to the pockets 415 when counter alignment structures 412 fit the alignment structures 272. In one embodiment, referring to FIG. 10, the pockets 415 provides three slots 180 degrees apart of the cutting ridge.

(26) The bit body in this embodiment can be a matrix body bit. Matrix bits include a mass of metal powder, such as tungsten carbide particles, infiltrated with a molten, subsequently hardened binder, such as a copper based alloy. Optionally, the bit may also be a steel or other bit type, such as a sintered metal carbide. Steel bits are generally made from a forging or billet, then machined to a final shape. The disclosure is not limited by the type of bit body employed for implementation of any embodiment thereof.

(27) In some other embodiments, the present disclosure provides a process to arrange a shaped cutter to a drill bit. The process includes configuring a bit body coupled to a plurality of blades; configuring a shaped cutter which is axially asymmetrical; based on the performance of the bit, determining the desired orientation of cutting face with respect to the formation of the shaped cutter; this step can be implemented by methods presented in U.S. Pat. No. 7,693,695 to Sujian, which is incorporated herein by reference.

(28) And then, according to the desired orientation of cutting face with respect to the formation of the shaped cutter, a blade profile of the blade, the position and orientation of a pocket relative to the blade profile and rotary orientation of the shaped cutter relative to the pocked is determined.

(29) Cutting at least one counter-alignment structure on the bottom of the pocket, fabricating corresponding alignment structure on the bottom of the shaped cutter, such that the shaped cutter has a determined rotary orientation relative to the pockets when the counter-alignment structures fit the alignment structures.

(30) In some embodiments, the performance of the bit is the weight on bit (WOB) or ROP. The alignment structure can be fabricated to cut the bottom of the substrate using laser cut or electrical discharge machining (EDM). The alignment structure can be a protrusion at the bottom of the substrate. The number of the slots in the pocket can be arbitrary, and equals to the number of alignment structures on the shaped cutter. The slots are distributed asymmetrically aterie along the circumference of the bottom of the pockets. In one embodiment, the pocket provides three slots 180 degrees apart of the cutting ridge. In one embodiment, the alignment structure is aligned a ridge of the shaped cutter.

(31) All of the compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this disclosure have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit and scope of the disclosure. More specifically, it will be apparent that certain agents which are related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the disclosure as defined by the appended claims.