Cutting Elements with Ridged and Inclined Cutting Face

Abstract

A drill bit for cutting formation comprises a bit body, a plurality of cutters, and a plurality of blades with pockets to accommodate the cutters, respectively. Each of the plurality of cutters has a substrate, an ultra-hard layer, an inclined surface on the top of the ultra-hard layer, wherein the inclined surface slants downward from a cutting edge to a trailing edge. The cutter can improve cutting efficiency and service life.

Claims

1. A cutter comprising a substrate; an ultra-hard layer; an inclined surface on top of the ultra-hard layer; and wherein the inclined surface slants downward from a cutting edge to a trailing edge.

2. The cutter of claim 1, further comprising a chamfer extending from a periphery of the inclined surface to the cutting edge at a side wall of the ultra-hard layer.

3. The cutter of claim 1, wherein the inclined surface comprises a cutting ridge extending from the cutting edge to the trailing edge diametrically on top of the inclined surface and two side surfaces slanting downward respectively from the cutting ridge to a periphery of the inclined surface.

4. The cutter of claim 3, wherein a profile angle at the trailing edge is larger than a profile angle at the cutting edge.

5. The cutter of claim 3, wherein the cutting ridge is a round cutting ridge.

6. The cutter of claim 1, wherein the cutter height at the cutting edge is taller than the cutter height at the trailing edge.

7. The cutter of claim 1, wherein the inclined surface comprises two cutting ridges intersecting at a cutting point on the cutting edge and extending from the cutting point to the trailing edge.

8. The cutter of claim 7, wherein the two cutting ridges separate the inclined surface into two side flat surfaces and a central flat surface; wherein the two side flat surfaces slant downward from the two cutting ridges to a periphery of the inclined surface; and wherein the central flat surface slants downward from the cutting edge to the trailing edge.

9. The cutter of claim 7, wherein the two cutting ridges separate the inclined surface into concave or convex surfaces.

10. The cutter of claim 1, wherein the inclined surface comprises two converging ridges and a central cutting ridge intersecting at a point away from the cutting edge, and the two converging ridges and the central cutting ridge divide the inclined surface into two side surfaces and one central surface.

11. The cutter of claim 10, wherein the two side surfaces are flat and the one central surface is flat.

12. The cutter of claim 10, wherein the two side surfaces intersect at the central cutting ridge and the two side surfaces intersect the central surface at the two converging ridges.

13. The cutter of claim 10, wherein the two cutting ridges separate the inclined surface into concave or convex surfaces.

14. The cutter of claim 10, wherein an outer end of the central cutting ridge meets the cutting edge at a cutting point; wherein the central cutting ridge is parallel to a cutter bottom surface of the substrate; and wherein the central surface has an inclination toward the trailing edge.

15. The cutter of claim 10, wherein the central cutting ridge is a round cutting ridge and forms a curved central surface; and wherein generating lines of the curved central surface are parallel to a bottom surface of the cutter or have a sloped angle to the bottom surface of the cutter.

16. The cutter of claim 15, wherein the curved central surface can be a concave or convex surface.

17. The cutter of claim 1, wherein the inclined surface comprises two cutting ridges which do not intersect at a point on a cutting surface and extend from a cutting point to the trailing edge.

18. The cutter of claim 17, wherein the two cutting ridges separate the inclined surface into two side flat surfaces and a central flat surface.

19. The cutter of claim 17, wherein the two cutting ridges are round; wherein a central flat surface slants downward from the cutting edge to the trailing edge; and wherein two side flat surfaces slant downward from the two cutting ridges to a periphery of the inclined surface.

20. The cutter of claim 17, wherein the two cutting ridges separate the inclined surface into concave or convex surfaces.

21. The cutter of claim 1, wherein the ultra-hard layer is formed of polycrystalline diamond.

22. The cutter of claim 1, wherein the inclined surface is loft cut by electrical discharge machining, by laser processing, by grinding, by other material reduction methods, or net shaping from a sintering process.

23. A drill bit comprising at least one cutter of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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:

[0023] FIG. 1 is a sectional view of a prior art drill bit;

[0024] FIG. 2A is a perspective view of a prior art cutter with planar cutting face;

[0025] FIG. 2B is a sectional view of the cutter in FIG. 2A;

[0026] FIG. 2C is a top view of the cutter in FIG. 2A;

[0027] FIG. 3A is a schematic illustration of a planar cutter cutting formation with larger back rake angle;

[0028] FIG. 3B is a schematic illustration of a planar cutter cutting formation with smaller back rake angle;

[0029] FIG. 4A is a perspective view of the cutter with nonplanar cutting face, which comprises two inclined side surfaces and one inclined cutting ridge in accordance with one embodiment of the present invention;

[0030] FIG. 4B is a front view of the cutter with nonplanar cutting face in FIG. 4A;

[0031] FIG. 4C is a sectional view of the cutter with nonplanar cutting face in FIG. 4A;

[0032] FIG. 5 is a schematic illustration of the cutter in FIG. 4A cutting formation with reduced back rake angle;

[0033] FIG. 6A is a perspective view of the nonplanar cutter in FIG. 4A with a round cutting ridge;

[0034] FIG. 6B is a front view of the nonplanar cutter in FIG. 6A;

[0035] FIG. 6C is a side view of the nonplanar cutter in FIG. 6A;

[0036] FIG. 7A is a perspective view of the cutter with nonplanar cutting face, which comprises three inclined flat surfaces converging at the cutting edge in accordance with one embodiment of the present invention;

[0037] FIG. 7B is a front view of the cutter with nonplanar cutting face in FIG. 7A;

[0038] FIG. 7C is a side view of the cutter with nonplanar cutting face in FIG. 7A;

[0039] FIG. 7D is a top view of the cutter with nonplanar cutting face in FIG. 7A with three inclined flat surfaces converging on the cutter periphery before the chamfer is constructed;

[0040] FIG. 8A is a perspective view of the cutter with three flat surfaces and three cutting ridges in accordance with one embodiment of the present invention;

[0041] FIG. 8B is a front view of the cutter with nonplanar cutting face in FIG. 8A;

[0042] FIG. 8C is a side view of the cutter with nonplanar cutting face in FIG. 8A;

[0043] FIG. 9 is a schematic illustration of the cutter in FIG. 8A cutting a highly heterogeneous formation with interbedded soft and hard sections;

[0044] FIG. 10A is a perspective view of the cutter with nonplanar cutting face, which comprises three inclined flat surfaces which do not intersect at a point on the cutting surface;

[0045] FIG. 10B is a front view of the cutter with nonplanar cutting face in FIG. 10A;

[0046] FIG. 10C is a side view of the cutter with nonplanar cutting face in FIG. 10A;

[0047] FIG. 11A is a perspective view of the nonplanar cutter in FIG. 8A with a round central cutting ridge;

[0048] FIG. 11B is a front view of the cutter with nonplanar cutting face in FIG. 11A;

[0049] FIG. 11C is a side view of the cutter with nonplanar cutting face in FIG. 11A.

DETAILED DESCRIPTION

[0050] 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.

[0051] 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 11th Edition.

[0052] FIGS. 4A-4C illustrate an embodiment of a cutter 51 of the present disclosure. In accordance with the present invention, the cutter 51 has a substrate 504 and an ultra-hard layer 502 disposed thereon. The ultra-hard layer 502 can be formed of polycrystalline diamond, cubic boron nitride, silicon carbide, and the substrate 504 can be formed of tungsten carbide. The cutter 51 is substantially cylindrical and symmetrical about a longitudinal cutter axis 505, although such symmetry is not required, and nonsymmetrical cutters are known in the art. A chamfer 507 extends from the periphery of a top surface 503 to a side wall 512 of the ultra-hard layer 502. Chamfer 507 may extend about the entire periphery of the ultra-hard layer 502 as shown or only a portion to be located adjacent to a cutting edge 521. Although the chamfer 507 can increase the durability of the cutting edge, it should be noted that cutters exhibiting substantially no visible chamber may be employed for certain applications in selected outer regions of a bit.

[0053] The top surface 503 of the cutter in the invention comprises two side surfaces 531, 533 which intersect at the center of the cutter and form a cutting ridge 541. The top surface 503 can be constructed from a typical flat cutter by removing materials with a method called loft cut. The cutting ridge 541 extends downward from the cutting edge 521 to the trailing edge 523 diametrically on the top surface 503. The two side surfaces 531, 533 are slanted downward respectively from the cutting ridge 541 to the periphery of the inclined top surface 503 along the perpendicular direction with respect to the cutting ridge. The intersection of the cutting ridge 541 and the cutting edge 521, the lowest point on the side surface 531, and the lowest point on the side surface 533 define three vertices of a cutting triangle. The projection of the cutting triangle on a plane perpendicular to the cutting ridge 541 will form a cutting triangle profile with three vertices 542, 524, 525. Similarly, the intersection of the cutting ridge 541 and trailing edge 523, the lowest point on the side surface 531, and the lowest point on the side surface 533 define three vertices of a trailing triangle. The trailing triangle projecting onto a plane perpendicular to the cutting ridge 541 will create a trailing triangle profile with three vertices 543, 524, 525.

[0054] The vertex 542 of the cutting triangle profile is higher than the vertex 543 of the trailing triangle profile. An angle between the line connecting vertices 542, 524 and the cutter axis 505 is defined as the first cutting edge profile angle 551, and an angle between the line connecting vertices 542, 525 and the cutter axis 505 is defined as the second cutting edge profile angle 552. An angle between a line connecting vertices 543, 524 and the cutter axis 505 is defined as the first trailing edge profile angle 555, and an angle between the line connecting vertices 543, 525 and the cutter axis 505 is defined as the second trailing edge profile angle 556. Using the line connecting the vertices of the triangle profiles as the guide curve, a convex surface can be formed. The slopes of the side surfaces are determined by the profile angles. The profile angles at the trailing edge are larger than the profile angles at the cutting edge to keep a reasonable diamond table thickness at the trailing edge 523. Specially, the first trailing edge profile angle 555 is larger than the first cutting edge profile angle 551, and the second trailing edge profile angle 556 is larger than the second cutting edge profile angle 552. The cutting ridge 541 is typically located at the center of the top surface. The profile angles of each profile may be equal or different. The loft cut is executed by Electrical Discharge Machining (EDM), Laser Ablation, Grinding, or other material reduction methods. It can also be net shaped through sintering process.

[0055] By constructing the cutter using the aforementioned methods, the cutter height 506 at the cutting edge is taller than the cutter height 508 at the trailing edge. The cutting ridge 541 is declining from the cutting edge to the trailing edge with an angle 509 larger than 90 degrees. The cutting ridge inclination is measured between the cutting ridge 541 and the cutter axis 505.

[0056] The advantage of the nonplanar cutter described in FIGS. 4A-4C can be explained in FIG. 5 and FIG. 3A. FIG. 3A shows a planar cutter cutting formation with a back rake angle 610 and a relief angle 620. FIG. 5 shows a cutter 51 with the inclined cutting face of FIG. 4A cutting formation with the same relief angle. When cutting into a formation 410, the planar cutter 5 and the non-planar cutter 51 have the same relief angle 620 in FIGS. 3A and 5. Because of the inclined cutting face, the back rake angle 613 of the cutter 51, which equals to the back rake angle 610 minus the inclination angle 509 in FIG. 4C plus 90 degrees, is smaller than the back rake angle 610 of the planar cutter 5. The reduced back rake angle and the sharp ridge of the nonplanar cutter in FIGS. 4A-4C requires less cutting force to fracture the formation while maintaining a reasonable relief angle.

[0057] There are some other advantages of the cutter described in FIGS. 4A-4C. The cuttings will remain in contact with the cutting face for a shorter period of time with the reduced back rake angle, resulting in less frictional heat. The frictional heat will deteriorate the properties of the ultra-hard layer such as wear resistance and impact resistance. The nonplanar cutting face provides a favorable fluid path, allowing the drilling fluid to cool the cutter more efficiently. The cutting ridge 541 and inclined side surfaces 531, 533 will break down the cuttings and reduce the tendency of cutting compaction in front of the cutting ridge, which might lead to other drilling dysfunctions such as poor cooling and even cutter balling.

[0058] In an embodiment of the present disclosure, the inclined cutting surface may have a round cutting ridge in the middle. FIGS. 6A-6C illustrate a cutter 52 having inclined surface and a round cutting ridge. Specifically, the cutter 52 has a substrate 504 and an ultra-hard layer 502 disposed thereon. A chamfer 507 extends from the periphery of the top surface 503 to the side wall 512 of the ultra-hard layer 502. The top surface 503 of the ultra-hard layer 502 is inclined. A cutting ridge 541 extends downward from a cutting edge 521 to a trailing edge 523 diametrically on the top surface 503. The two side surfaces 531, 533 are slanted downward respectively from the cutting ridge 541 to the periphery of the inclined top surface 503 along the perpendicular direction with respect to the cutting ridge 541. At the same time, the two side surfaces 531, 533 are slanted downward respectively from the cutting edge 521 to the trailing edge 523.

[0059] As will be recognized by those skilled in the art, there are other cutter designs in accordance with the features of this invention. In a preferred embodiment, Referring to FIGS. 7A-7D, a cutter 53 having inclined surface is illustrated. The cutter 53 has a substrate 504 and an ultra-hard layer 502 disposed thereon. A chamfer 507 extends from the periphery of a top surface 503 to the side wall 512 of the ultra-hard layer 502. The top surface 503 of the ultra-hard layer 502 is inclined.

[0060] The top surface 503 comprises two inclined flat side surfaces 531 and 533 and an inclined flat central surface 532. The central surface 532 has an inclination α between the central surface 532 and the bottom surface of the cutter. The inclination α, in the range of 1-45 degrees, preferred in the range of 3-15 degrees, determines the back rake angle reduction compared to a flat cutter. The side surfaces 531, 533 have inclinations β and γ with their lower sides intersecting cutter cylindrical surface. The inclinations β and γ are measured between the side surfaces 531, 533 and a cutter axis 505, respectively. The three surfaces intersect at two cutting ridges 541, 561. Specifically, the flat side surface 531 intersects with the central surface 532 at the cutting ridge 541, and the flat side surface 533 intersects with the central surface 532 at the cutting ridge 561. Referring to FIG. 7D, the cutting ridges 541, 561 intersect the cutter periphery at the point 571 before the chamfer is constructed and extend from the point 571 to the trailing edge, such that the two cutting ridges form a substantially “V” type pattern. Referring to FIG. 7A, after the chamfer 507 is constructed, the cutting ridges 541, 561 intersect the cutting edge 521 at the points 572 and 573. The two side surfaces 53 land 533 and the central surface 532 slant downward respectively from the cutting edge 521 to the trailing edge 523, at the same time, the side surfaces 531, 533 slant downward respectively from the two cutting ridges 541, 561 to the cutter periphery. The side surfaces are symmetric with regard to the plane which passes through point 522 having equal distance to the points 572 and 573 and the cutter axis 505 in FIGS. 7A-7B, in which case the inclinations β and γ are equal, but they can be asymmetric in other embodiments.

[0061] FIGS. 8A-8C illustrate an alternative embodiment of a cutter 54 of the present disclosure. Similar to the cutter in FIGS. 7A-7D, the cutting face features three inclined flat surfaces, but they intersect at a point away from the cutting edge. The cutter 54 has a substrate 504 and an ultra-hard layer 502 disposed thereon. A chamfer 507 extends from the periphery of the top surface 503 to the side wall 512 of the ultra-hard layer 502. The central cutting ridge is parallel to the cutter bottom surface and two diverging cutting ridges extend downward to the cutter periphery at the trailing edge.

[0062] The top surface 503 of the ultra-hard layer 502 is inclined and provided with three cutting ridges 541, 562 and 563. The inner ends (away from the cutter periphery) of the three cutting ridges converge at a point 545 on the top surface 503, and the outer ends (close to the cutter periphery) of the three cutting ridges extend to the outer edge of the top surface 503. Viewed from the top of the cutter, the three cutting ridges form a substantially “Y” type pattern, and the three cutting ridges divide the top surface into two flat side surfaces 531, 533 and one flat central surface 532. The two flat side surfaces 531, 533 intersect at the central cutting ridge 541. The outer end (close to the cutter periphery) of the central cutting ridge 541 meets the cutting edge 521 at a cutting point. The two flat side surfaces 531, 533 intersect the central surface 532 at two diverging cutting ridges 562 and 563, respectively. In one embodiment, the central cutting ridge 541 is parallel to the cutter bottom surface and two diverging cutting ridges 562, 563 extend downward to the cutter periphery at the trailing edge 523. A slope is measured between the central flat surface and a plane parallel to the cutter bottom surface. In FIG. 8B, the central surface 532 has a slope angle S. It is worth mentioning that the central cutting ridge 541 is parallel to the cutter bottom surface in FIGS. 8A-8C, but it can slant downwards from the cutting edge to the central flat surface with a slope angle which is smaller than the slope angle δ of the central surface.

[0063] The central ridge cuts the formation and its length can be optimized based the depth of cut in highly heterogeneous formation where soft and hard layers are alternating. The embodiment in FIGS. 8A-8C can adapt to the formation change with a stepped back rake configuration. Referring to FIG. 9, formation 410 is a highly heterogeneous formation with hard and soft layers. When a bit is in a relative hard layer within the highly heterogeneous formation 410, a larger back rake angle is preferred to maintain cutter edge strength in preventing breakage or chipping due to high cutting forces acting on the cutters. However, when the bit is cutting a relative soft layer within the highly heterogeneous formation, a smaller back rake angle is preferred to improve the cutting efficiency. Particularly, when cutting into the hard layer of the formation 410, a cutter 54 produces a hard formation ribbon 414 with a low depth of cut 415. In the low depth of cut, the cutting ridge 541 contact with the hard formation ribbon, and a back rake angle α is the angle between the cutting ridge 541 and the line 411 normal to the surface of formation 410. When cutting into the soft layer of the formation 410, the cutter produces a soft formation ribbon 418 with a high depth of cut 419. In the high depth of cut, a back rake angle β is the angle between the central surface 532 and the line 411. Because of the slope angle δ of the central surface 532, the back rake angle β is smaller than the back rake angle α, which allows higher rate of penetration. Therefore, the cutter of the present invention can adjust the back rake angle in a heterogeneous formation with the same relief angle, such that the cutter can improve cutting efficiency and service life.

[0064] FIGS. 10A-10C illustrate an alternative embodiment of a cutting element 55 of the present disclosure. Similar to the cutter in FIGS. 7A-7D and FIGS. 8A-8C, the cutting face features three inclined flat surfaces, but the three inclined flat surfaces do not interest at a point on the cutting surface.

[0065] The cutter 55 has a substrate 504 and an ultra-hard layer 502 disposed thereon. A chamfer 507 extends from the periphery of the top surface 503 to the side wall 512 of the ultra-hard layer 502. The top surface 503 comprises two inclined flat side surfaces 531, 533 and an inclined flat central surface 532. The central surface 532 has an inclination α between the central surface 532 and the bottom surface of the cutter. The side surfaces 531, 533 have inclinations β and γ with their lower sides intersecting cutter cylindrical surfaces. The inclinations β and γ are measured between the side surfaces 531, 533 and a cutter axis 505, respectively. The three surfaces intersect at two cutting ridges 541, 569. Specifically, the flat side surface 531 intersects with the central surface 532 at the cutting ridge 541, and the flat side surface 533 intersects with the central surface 532 at the cutting ridge 569. The cutting ridges 541, 569 intersect the cutting edge 521 at points 567 and 568 and intersect the trailing edge 523 at points 553 and 554. The two side surfaces 53 land 533 and central surface 532 slant downward respectively from the cutting edge 521 to the trailing edge 523, at the same time, the side surfaces 531, 533 slant downward respectively from the two cutting ridges 541, 569 to the cutter periphery. It is worth mentioning that the side surfaces are symmetric with regard to the plane which passes through the point having equal distance to the points 567 and 568 and the cutter axis 505 in FIGS. 10A-10B, in which case the inclinations β and γ are equal, but they can be asymmetric in other embodiments. The cutting ridge 541, 569 in the present disclosure are sharp, but they can also be round to improve their impact resistance. FIGS. 11A-11C illustrate an alternative embodiment of a cutting element 56 of the present disclosure. Similar to the cutter in FIGS. 8A-8C, but the central ridge is rounded and forms a curved surface 534 where the generating lines 547 are parallel to each other. Specifically, the cutter 56 has a substrate 504 and an ultra-hard layer 502 disposed thereon. A chamfer 507 extends from the periphery of the top surface 503 to the side wall 512 of the ultra-hard layer 502. The top surface 503 includes a central curved surface 534, a central flat surface 532 and two flat side surfaces 531 and 533. The two flat side surfaces 531, 533 intersect the central curved surface 534 at the cutting ridges 541 and 566 and intersect the central flat surface 532 at the cutting ridges 564 and 565. The central curved surface 534 intersects the central flat surface 532 at the cutting ridge 570 and intersects the side wall 512 of the ultra-hard layer 502 at the edge 546, as part of the cutting edge 521.

[0066] The top surface 503 of the ultra-hard layer 502 is inclined. The central surface 532 has a slope angle S. The two side surfaces 531, 533 are slanted downward respectively from the cutting ridges 541 and 566 to the periphery of the inclined top surface 503 along the perpendicular direction with respect to the cutting ridges 541 and 566, respectively. At the same time, the two side surfaces 531, 533 are slanted downward respectively from the cutting edge 521 to the trailing edge 523. The generating lines 547 of the central curved surface 534 are parallel to the bottom surface of the cutter or have a sloped angle to the bottom surface of the cutter (not shown).

[0067] For the cutters in FIGS. 7A-7D, FIGS. 8A-8C, FIGS. 10A-10C, and FIGS. 11A-11C, the cutting faces are constructed by three flat surfaces except the additional central curved surface in FIGS. 11A-11C. Other shapes of the surfaces, such as any convex or concave surfaces, shall also be included in the disclosure.

[0068] In some embodiments, the present invention also provides a drill bit, which comprises at least one cutter disclosed in this invention in any position.

[0069] 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 both chemically 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.