Abstract
In a fixed cutter drill bit, a hybrid cutter with a cutting edge including a substantially continuous curve interrupted by at least one arc discontinuity. In a fixed cutter drill bit, a contoured cutter with a contoured cutting face including a raised shape, wherein the raised shape has a raised shape axis which is oblique to a drill bit body axis. In a cutter for a fixed cutter drill bit, a chamfer including a side bevel and a cutting face bevel, wherein a cutting face bevel length is at least two times a side bevel length.
Claims
1. A fixed cutter drill bit comprising: (a) a drill bit body having a distal end and a drill bit body axis; and (b) a contoured cutter positioned on the distal end of the drill bit body, wherein the contoured cutter comprises a cutter element, wherein the cutter element defines a cutting face, wherein the cutting face is a contoured cutting face, wherein the contoured cutting face is comprised of a raised shape extending away from the distal end of the drill bit body in a distal direction, wherein the raised shape defines a raised shape axis, wherein the raised shape axis is oblique to the drill bit body axis, wherein the contoured cutter is a center cutter, and wherein the center cutter is positioned on the distal end of the drill bit body such that the raised shape axis of the center cutter intersects the drill bit body axis.
2. The fixed cutter drill bit as claimed in claim 1 wherein the drill bit is comprised of a plurality of contoured cutters, wherein each of the contoured cutters is positioned on the distal end of the drill bit body, wherein each of the contoured cutters comprises a cutter element, wherein the cutter element defines a cutting face, wherein the cutting face is a contoured cutting face, wherein the contoured cutting face is comprised of a raised shape extending away from the distal end of the drill bit body in the distal direction, wherein the raised shape defines a raised, shape axis, and wherein the raised shape axis is oblique to the drill bit body axis.
3. The fixed cutter drill bit as claimed in claim 1 wherein the center cutter defines a center cutter axis and wherein the center cutter axis is coincident with the drill bit body axis.
4. The fixed cutter drill bit as claimed in claim 1 wherein the raised shape is cone-shaped between a base and a tip.
5. The fixed cutter drill bit as claimed in claim 4 wherein the raised shape is selected from the group of shapes consisting of a straight cone, a concave cone, a convex cone, and a polygonal cone.
6. The fixed cutter drill bit as claimed in claim 5 wherein the tip of the raised shape is spherical.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1) Embodiments of the invention will now be described with reference to the accompanying drawings, in which:
(2) FIG. 1 is a pictorial view of a first embodiment of drill bit including features of the invention.
(3) FIG. 2 is a pictorial view of a second embodiment of drill bit including features of the invention.
(4) FIG. 3 is an end view of the distal end of the second embodiment of drill bit depicted in FIG. 2.
(5) FIG. 4 is a depiction of geometric shapes which may be represented in hybrid cutters according to the invention.
(6) FIG. 5 is a pictorial view of an embodiment of a hybrid cutter according to the invention which incorporates features of the geometric shapes of FIG. 4.
(7) FIG. 6 is a detail view of the curved cutter tip of the hybrid cutter depicted in FIG. 5.
(8) FIG. 7 is a view of the cutting faces of a pair of adjacent hybrid cutters according to an embodiment of the invention, arranged in an embodiment of a combined cutter configuration according to the invention.
(9) FIG. 8 is a view of the cutting faces of a pair of adjacent hybrid cutters according to an embodiment of the invention, arranged in an embodiment of a combined cutter configuration according to the invention.
(10) FIG. 9 is a view of the cutting faces of a pair of adjacent hybrid cutters according to an embodiment of the invention, arranged in an embodiment of a combined cutter configuration according to the invention.
(11) FIG. 10 is a view of the cutting face of an embodiment of a hybrid cutter according to the invention.
(12) FIG. 11 is a view of the cutting face of an embodiment of a hybrid cutter according to the invention.
(13) FIG. 12 is a view of the cutting face of an embodiment of a hybrid cutter according to the invention.
(14) FIG. 13 is a view of the cutting face of an embodiment of a hybrid cutter according to the invention.
(15) FIG. 14 is a view of the cutting face of an embodiment of a hybrid cutter according to the invention.
(16) FIG. 15 is a view of the cutting face of an embodiment of a hybrid cutter according to the invention.
(17) FIG. 16 is a view of the cutting face of an embodiment of a hybrid cutter according to the invention.
(18) FIG. 17 is a pictorial view of an embodiment of a cutter for a fixed cutter drill bit, depicting an alignment aid associated with the cutter.
(19) FIG. 18 is a pictorial view of an embodiment of a cutter for a fixed cutter drill bit, depicting an alignment aid associated with the cutter.
(20) FIG. 19 is a pictorial view of an embodiment of a cutter for a fixed cutter drill bit, depicting an alignment aid associated with the cutter.
(21) FIG. 20 is a pictorial view of an embodiment of a cutter for a fixed cutter drill hit, depicting an alignment aid associated with the cutter.
(22) FIG. 21 is a pictorial view of an embodiment of a cutter for a fixed cutter drill bit, depicting an alignment aid associated with the cutter.
(23) FIG. 22 is a pictorial view of an embodiment of a cutter for a fixed cutter drill bit, depicting an alignment aid associated with the cutter.
(24) FIG. 23 is a schematic view of the distal end of a prior art fixed cutter drill bit body and a borehole being contacted by the drill bit, depicting a core of undrilled material being formed at the drill bit body axis.
(25) FIG. 24 is a pictorial view of the distal end of the first embodiment of drill bit depicted in FIG. 1, detailing an embodiment of a contoured cutter according to the invention.
(26) FIG. 25 is a side view of an embodiment of a contoured cutter according to the invention.
(27) FIG. 26 is a side view of a contoured cutter according to the invention.
(28) FIG. 27 is a side view of an embodiment of a contoured cutter according to the invention.
(29) FIG. 28 is a side view of an embodiment of a contoured cutter according to the invention.
(30) FIG. 29 is a schematic view of an embodiment of an embodiment of a chamfer of a cutting edge of a cutter according to the invention.
DETAILED DESCRIPTION
(31) The present invention relates to fixed cutter drill bits and to features of a fixed cutter drill bit.
(32) A first embodiment of a fixed cutter drill bit incorporating embodiments of features of the invention is depicted in FIG. 1 and FIG. 24. A second embodiment of a fixed cutter drill bit incorporating embodiments of features of the invention is depicted in FIG. 2 and FIG. 3.
(33) Exemplary embodiments of hybrid cutters according to the invention are depicted in FIGS. 5-16. Exemplary embodiments of alignment aids for hybrid cutters according to the invention are depicted in FIGS. 17-22. Exemplary embodiments of contoured cutters according to the invention are depicted in FIGS. 24-28. An exemplary embodiment of a chamfer for a fixed cutter according to the invention is depicted in FIG. 29.
(34) Referring to FIGS. 1-3, a fixed cutter drill hit (20) is comprised of a drill bit body (22) and has a gauge diameter (24).
(35) The drill bit body (22) has a drill bit body axis (26). The drill bit body (22) has a proximal end (28) which is adapted for connecting with a drill string (not shown), a distal end (30) and a plurality of blades (32). The drill bit body (22) defines a bit bore (not shown) which extends through the drill bit body (22) from the proximal end (28) and a plurality of nozzles (36) adjacent to the distal end (30) which communicate with the bit bore to provide a path for a drilling fluid (not shown) to be passed through the drill string and the drill bit (20). The drill bit body (22) also defines a cone recess (38) having a cone recess diameter (40). The center of the cone recess diameter (40) coincides with the drill bit body axis (26).
(36) In the embodiments depicted in the Figures, the drill bit body (22) may be constructed of steel and the drill bit body (22) may be milled as one piece from a single block of steel. Alternatively, the drill bit body (22) may be constructed from a plurality of components which are subsequently connected together.
(37) In the embodiments depicted in the Figures, the proximal end (28) of the drill bit body (22) is comprised of a threaded pin connector (44).
(38) In the embodiments depicted in the Figures, the drill bit body (22) is comprised of five blades (32) which extend as spirals from the distal end (30) of the drill bit body (22) toward the proximal end of the drill bit body (22). Two of the blades (32) are primary blades (50) which extend radially to the drill bit body axis (26) and three of the blades (32) are secondary blades (52) which do not extend radially to the drill bit body axis (26).
(39) The blades (32) define a cutting profile (54) which extends radially between the drill bit body axis (26) and the gauge diameter (24).
(40) A plurality of cutters (60) is attached to the blades (32). The cutters (60) are distributed on the blades (32) in a cutter layout (62) along the cutting profile (54).
(41) The cutters (60) are comprised of cutter elements (64) and substrates (66). The cutter elements (64) are affixed to the substrates (66).
(42) In the embodiments depicted in the Figures, the cutter elements (64) may be constructed of polycrystalline diamond compact (PDC) or any other suitable material. The cutter elements (64) comprise cutting faces (68). The cutting faces (68) contact the borehole (not shown) during drilling to perform a shearing action.
(43) In the embodiment of the invention depicted in the Figures, the substrates (66) may be constructed of tungsten carbide or any other suitable material.
(44) The drill bit body (22) defines cutter pockets (70) along the blades (32). The cutters (60) are received in the cutter pockets (70) for positioning of the cutters (60) on the blades (32). In the embodiment depicted in the Figures, the cutters (60) may be attached to the blades (32) by brazing the substrates (66) into the cutter pockets (70).
(45) In addition to the cutters (60) which are provided in the cutter layout (62), a plurality of gauge cutters (72) are located on each of the blades (32) between the proximal end (28) and the distal end (30) of the drill bit body (22). As depicted in the Figures, the gauge cutters (72) include active gauge trimmer cutters and passive gauge or gauge pad cutters.
(46) The cutter layout (62) defines exposures, siderake angles, backrake angles, cutting edges and cutting paths for individual cutters (60) in the cutter layout (62). The cutter layout (62) also defines effective cutting edges and effective cutting paths for all of the cutters (60) in the cutter layout (62), having regard to cutter offsets and relative exposures of the cutters (60).
(47) Referring to FIG. 1 and FIG. 24, the cutter layout (62) of the first embodiment of fixed cutter drill bit (20) includes a plurality of hybrid cutters (80) and one contoured cutter (82). Referring to FIG. 2 and FIG. 3, the cutter layout (62) of the second embodiment of fixed cutter drill bit (20) includes a plurality of hybrid cutters (80) and a plurality of contoured cutters (82).
(48) Referring to FIG. 4, a number of possible geometric shapes for fixed cutters are depicted schematically. These geometric shapes illustrate the manner in which the hybrid cutters (80) of the invention combine features of angular cutters and curved cutters and depict the evolution of the hybrid cutters (80) from angular cutters and curved cutters, culminating in the hybrid cutter (80) shown at the far right side of FIG. 4.
(49) Referring to FIG. 5 and FIG. 6, an embodiment of a hybrid cutter (80) is depicted, wherein the embodiment is a refined version of the hybrid cutter (80) shown in FIG. 4. In FIG. 5, the hybrid cutter (80) is comprised of a cutter element (64) and a substrate (66). The cutter element (90) defines a cutting face (68). The cutting face (68) has a perimeter (88). In the embodiment of FIGS. 5-6, the cutting face (68) is comprised of a substantially continuous curve (90), interrupted by two arc discontinuities (92). In the embodiment of FIGS. 5-6, the substantially continuous curve (90) is substantially circular, and the two arc discontinuities (92) are straight discontinuities which may be described as chords in the cutting face (68). In the embodiment of FIGS. 5-6, the two arc discontinuities (92) extend for the full length (93) of the cutter (60).
(50) In the embodiment of FIGS. 5-6, the cutting face (68) is further comprised of a curved cutter tip (94) between the two arc discontinuities (92). The curved cutter tip (94) is a portion of the substantially continuous curve (90).
(51) The embodiment of hybrid cutter (80) depicted in FIGS. 5-6 is substantially symmetrical about the curved cutter tip (94). When the embodiment of hybrid cutter (80) of FIGS. 5-6 is positioned on the drill bit body (22), a portion of the cutting face (68) will exhibit an exposure (96) which defines a cutter centerline (98) normal to the drill bit body (22). The perimeter around the portion of the cutting face (68) which exhibits the exposure (96) will provide a cutting edge (100). Preferably, the hybrid cutter (80) is positioned on the drill bit body (22) no that the two arc discontinuities (92) do not intersect the cutter centerline (98) and so that the cutter centerline (98) intersects the curved cutter tip (94). More preferably, the hybrid cutter (80) is positioned on the drill bit body (22) so that the portion of the cutting face (68) which exhibits the exposure (96) is substantially symmetrical about the cutter centerline (98).
(52) Referring to FIGS. 7-16, various embodiments of hybrid cutters (80) and configurations of hybrid cutters (80) are depicted. In the description of FIGS. 7-16 which follows, features of the hybrid cutters (80) which correspond to features of the embodiment of hybrid cutter (80) of FIGS. 5-6 share the reference numbers used for the embodiment of FIGS. 5-6.
(53) FIGS. 7-9 depict combined cutter configurations (110) for several embodiments of two hybrid cutters (80) according to the first aspect of the invention. In all of FIGS. 7-9, the combined cutter configuration (110) is comprised of a hybrid cutter (80) and a second hybrid cutter (112). The hybrid cutter (80) and the second hybrid cutter (112) are depicted in FIGS. 7-9 as positioned on the drill bit body (22).
(54) In each of FIGS. 7-9, the hybrid cutter (80) and the second hybrid cutter (112) are substantially identical to each other. In all of FIGS. 7-9, each of the hybrid cutter (80) and the second hybrid cutter (112) is comprised of a substantially continuous curve (90) interrupted by one arc discontinuity (92). In all of FIGS. 7-9, the substantially continuous curve (90) is substantially circular. In FIG. 7, the one arc discontinuity (92) is a substantially straight discontinuity. In FIG. 8, the one arc discontinuity (92) is a substantially concave discontinuity. In FIG. 9, the one arc discontinuity (92) is a substantially convex discontinuity. In all of FIGS. 7-9, the arc discontinuities (92) extend for the full length (not shown in FIGS. 7-9) of the cutter (60).
(55) In each of FIGS. 7-9, the hybrid cutter (80) defines a cutter centerline (98) normal to the drill bit body (22) and the second hybrid cutter (112) defines a second cutter centerline (114) normal to the drill bit body (22). In each of FIGS. 7-9, the cutter centerline (98) and the second cutter centerline (114) are substantially parallel to each other. In each of FIGS. 7-9, the combined cutter configuration (100) defines a combined cutter centerline (116).
(56) In each of FIGS. 7-9, the one arc discontinuity (92) of the hybrid cutter (80) does not intersect the cutter centerline (98) and the one arc discontinuity (92) of the second hybrid cutter (112) does not intersect the second cutter centerline (114). In each of FIGS. 7-9, the one arc discontinuity (92) of the hybrid cutter (80) and the one arc discontinuity (92) of the second hybrid cutter (112) are facing each other. In each of FIGS. 7-9, the combined cutter configuration (110) is substantially symmetrical about the combined cutter centerline (116).
(57) FIGS. 10-12 depict several further embodiments of hybrid cutters (80) according to the first aspect of the invention.
(58) In all of FIGS. 10-12, each of the hybrid cutters (80) is comprised of a substantially continuous curve (90) interrupted by two arc discontinuities (92). In all of FIGS. 10-12, the substantially continuous curve (90) is substantially circular. In all of FIGS. 10-12, the cutting edge (100) of the hybrid cutters (80) is further comprised of curved cutter tips (94) between the arc discontinuities (92). In FIG. 10, each of the two arc discontinuities (92) is a substantially straight discontinuity. In FIG. 11, each of the two arc discontinuities (92) is a substantially concave discontinuity. In FIG. 12, each of the two arc discontinuities (92) is a substantially convex discontinuity. In all of FIGS. 10-12, each of the two arc discontinuities (92) extends for the full length (not shown in FIGS. 10-12) of the cutter (60).
(59) In each of FIGS. 10-12, the hybrid cutter (80) defines a cutter centerline (98) normal to the drill bit body (22).
(60) In each of FIGS. 10-12, the two arc discontinuities (92) of the hybrid cutter (80) do not intersect the cutter centerline (98). In each of FIGS. 10-12, the cutter centerline (98) intersects one of the curved cutter tips (94). In each of FIGS. 10-12, the hybrid cutter (80) is substantially symmetrical about the cutter centerline (98).
(61) FIGS. 13-16 depict several further embodiments of hybrid cutters (80) according to the first aspect of the invention.
(62) In all of FIGS. 13-16, each of the hybrid cutters (80) is comprised of a substantially continuous curve (90) interrupted by at least three arc discontinuities (92). In all of FIGS. 13-16, the substantially continuous curve (90) is substantially circular. In all of FIGS. 13-16, the cutting edge (100) of the hybrid cutters (80) is further comprised of curved cutter tips (94) between the arc discontinuities (92). In FIG. 13, each of the three arc discontinuities (92) is a substantially concave discontinuity. In FIG. 14, each of the three arc discontinuities (92) is a substantially convex discontinuity. In FIG. 15, each of the nine arc discontinuities (92) is a notch discontinuity. In FIG. 16, each of the nine arc discontinuities (92) is a substantially concave discontinuity. In all of FIGS. 13-16, each of the arc discontinuities (92) extends for the full length (not shown in FIGS. 13-16) of the cutter (60).
(63) In each of FIGS. 13-16, the hybrid cutter (80) defines a cutter centerline (98) normal to the drill bit body (22).
(64) In each of FIGS. 13-16, the arc discontinuities (92) of the hybrid cutter (80) do not intersect the cutter centerline (98). In each of FIGS. 13-16, the cutter centerline (98) intersects one of the curved cutter tips (94). In each of FIGS. 13-16, the hybrid cutter (80) is substantially symmetrical about the cutter centerline (98).
(65) In each of FIGS. 13-16, the arc discontinuities (92) are substantially evenly spaced around the perimeter (88) of the cutting face (68). As a result, the cutter pockets (70) for the hybrid cutters (80) of FIGS. 13-16 may be provided with complementary surfaces (not shown) to receive one or more of the arc discontinuities (92). The arc discontinuities (92) and the complementary surfaces may assist in positioning the hybrid cutters (80) on the drill bit body (22) and may thus function as alignment aids. In addition, a worn or damaged cutting face (68) on the hybrid cutter (80) can be changed by turning the hybrid cutter (80) to change the portion of the cutting face (68) which exhibits the exposure (96) so that the hybrid cutter (80) can be re-used instead of discarded.
(66) FIGS. 17-22 depict several embodiments of alignment aids (120) which may be suitable for hybrid cutters (80) and for other cutters (60) positioned on the drill bit body (22). FIG. 17 depicts a single hole which may be provided on the end of the substrate (66) opposite the cutter element (64) and which may be complementary with a lug (not shown) in a cutter pocket (70). FIG. 18 depicts a single lug which may be provided on the end of the substrate (66) opposite the cutter element (64) and which may be complementary with a hole (not shown) in a cutter pocket (70). FIG. 19 depicts a single groove which may be provided on the end of the substrate (66) opposite the cutter element (64) and which may be complementary with a lug (not shown) in a cutter pocket (70). FIG. 20 depicts a plurality of holes which may be provided on the end of the substrate (66) opposite the cutter element (64) and which may be complementary with a plurality of lugs (not shown) in a cutter pocket (70). FIG. 21 depicts a plurality of lugs which may be provided on the end of the substrate (66) opposite the cutter element (64) and which may be complementary with a plurality of holes (not shown) in a cutter pocket (70). FIG. 22 depicts a plurality of grooves which may be provided on the end of the substrate (66) opposite the cutter element (64) and which may be complementary with a plurality of lugs (not shown) in a cutter pocket (70).
(67) Referring again to FIG. 1 and FIG. 21 depicting the first embodiment of drill bit (20) and FIGS. 2-3 depicting the second embodiment of drill bit (20), each of the first embodiment and the second embodiment include a similar configuration of hybrid cutters (80). Specifically, each of the five blades (32) of the drill bit (20) includes four hybrid cutters (80). Of these four hybrid cutters (80), three hybrid cutters (80) are similar to the embodiment of hybrid cutter (80) depicted in FIGS. 4-5 and FIG. 10 and are positioned on the distal end (30) of the drill bit body (22).
(68) The fourth hybrid cutter (80) on each blade (32) is similar to the embodiment of hybrid cutter (80) depicted in FIG. 7 and is positioned on the side of the drill bit body (22). As depicted in FIG. 1 and FIG. 24 and FIGS. 2-3, the one arc discontinuity (92) of the fourth hybrid cutter (80) is tapered along the length of the cutter element (64) and does not extend to the substrate (66) or along any portion of the length of the substrate (66).
(69) In other embodiments of a drill bit (20) according to the invention, fewer or more hybrid cutters (80) may be provided than are depicted in FIG. 1 and FIG. 24 and FIGS. 2-3, the hybrid cutters (80) may be configured on the drill bit body (22) in a different manner than is depicted in FIG. 1 and FIG. 24 and FIGS. 2-3, and the hybrid cutters (80) may consist of or may include other embodiments of hybrid cutter (80) as described herein than are depicted in FIG. 1 and FIG. 24 and FIGS. 2-3.
(70) Referring to FIG. 23, a schematic view is provided of the distal end (30) of a fixed cutter drill bit body (22) and a borehole (122) being contacted by the drill bit (20), depicting a core (124) of undrilled material being formed at the drill bit body axis (26). Although this core (124) of undrilled material may enhance the stability of the drill bit (20), the core (124) may also impose undesirable side loading on cutters (60) positioned adjacent to the drill bit body axis (26).
(71) FIGS. 24-28 depict several embodiments of contoured cutters (82) according to the second aspect of the invention. FIG. 1 and FIG. 24 provide an exemplary configuration for contoured cutters (82) on the first embodiment of drill bit (20). FIG. 2 and FIG. 3 provide an alternate exemplary configuration for contoured cutters (82) on the second embodiment of drill bit (20).
(72) Referring to FIG. 1 and FIG. 24, an exemplary configuration of contoured cutters (82) is depicted on the first embodiment of drill bit (20). As depicted in FIGS. 1 and 24, the first embodiment of drill bit (20) is comprised of a single contoured cutter (82).
(73) FIG. 24 is a detail view of the distal end (30) of the drill bit body (22) at the drill bit body axis (26) of the first embodiment of drill bit (20) depicted in FIG. 1. FIG. 24 depicts an embodiment of a contoured cutter (82) which is configured as a center cutter. The contoured cutter (82) depicted in FIG. 24 comprises a cutter element (64) and a cutter substrate (66). The cutter element (64) defines a cutting face (68).
(74) The cutting face (68) is a contoured cutting face which is comprised of a raised shape (130) extending away from the distal end (30) of the drill bit body (22) in a distal direction. The contoured cutter (82) defines a center cutter axis (132). The raised shape (130) defines a raised shape axis (134). As depicted in FIG. 24, the raised shape axis (134) is coincident with the center cutter axis (132). As a result, the contoured cutter (82) is tilted in its cutter pocket (70) so that the raised shape axis (134) is oblique to the drill bit body axis (26). As depicted in FIG. 24, the raised shape axis (134) intersects the drill bit body axis (26).
(75) As depicted in FIG. 24, the raised shape (130) is substantially cone-shaped between a base (136) and a tip (138). In particular, as depicted in FIG. 24, the raised shape (130) is substantially a straight cone in which the sides of the raised shape (130) are substantially straight and provide a taper between the base (136) and the tip (138). As depicted in FIG. 24, the tip (138) of the raised shape (130) is substantially spherical.
(76) Referring to FIG. 2 and FIG. 3, an alternate exemplary configuration of contoured cutters (82) is depicted. As depicted in FIGS. 2-3, the second embodiment of drill bit (20) is comprised of five contoured cutters (82).
(77) Referring to FIG. 3, one of the contoured cutters (82) is configured as a center cutter, two of the contoured cutters (82) are positioned on the drill bit body (22) so that the tips (138) of the contoured cutters (82) are located at a first diameter (146) from the drill bit body axis (26) and two of the contoured cutters (82) are positioned on the drill bit body (22) so that the tips (138) of the contoured cutters (82) are located at a second diameter (148) from the drill bit body axis (26).
(78) The first diameter (146) and/or the second diameter (148) may be considered to define a center portion of the drill bit (20) so that the contoured cutters (82) may be considered to be positioned within a center portion of the drill bit (20). In some embodiments of the second aspect, one of the first diameter (146) or the second diameter (148) may coincide with the cone recess diameter (40).
(79) The configuration of a plurality of contoured cutters (82) depicted in FIGS. 2-3 is exemplary only, and other configurations of a plurality of contoured cutters (82) may be provided.
(80) In the alternate configuration of contoured cutters (82) depicted in FIGS. 2-3, each of the contoured cutters (82) comprises a cutter element (64) and a substrate (66). The cutter element (64) of each of the contoured cutters (82) defines a cutting face (68).
(81) The cutting face (68) of each of the contoured cutters (82) depicted in FIGS. 2-3 is a contoured cutting face which is comprised of a raised shape (130) extending away from the distal end (30) of the drill bit body (22) in a distal direction. The center cutter defines a center cutter axis (132) and the other contoured cutters (82) define a contoured cutter axis (160). The raised shape (130) of each of the contoured cutters (82) defines a raised shape axis (134). As depicted in FIGS. 2-3, each of the contoured cutters (82) is tilted in its respective cutter pocket (70) so that the raised shape axis (134) of each of the contoured cutters (82) is oblique to the drill bit body axis (26). The raised shape axis (134) of the center cutter intersects the drill bit body axis (26).
(82) As depicted in FIGS. 2-3, the raised shape (130) of each of the contoured cutters (82) is substantially cone-shaped between a base (136) and a tip (138). In particular, as depicted in FIGS. 2-3, the raised shape (130) is substantially a straight cone in which the sides of the raised shape (130) are substantially straight and provide a taper between the base (136) and the tip (138). As depicted in FIG. 24, the tip (138) of the raised shape (130) of each of the contoured cutters (82) is substantially spherical.
(83) FIGS. 25-28 provide side views depict various embodiments of contoured cutters (82) in which the raised shapes (130) are substantially cone-shaped. FIG. 25 depicts a substantially straight cone, FIG. 26 depicts a substantially concave cone, FIG. 27 depicts a substantially convex cone, and FIG. 28 depicts a substantially polygonal cone. In some embodiments of the second aspect, other substantially cone-shaped shapes may be provided for the raised shape (130), and shapes other than cones may be utilized for the contoured cutters (82).
(84) In other embodiments of a drill bit (20) according to the invention, fewer or more contoured cutters (82) than are depicted in FIG. 1 and FIG. 24 and FIGS. 2-3 may be provided, the contoured cutters (82) may be configured on the drill bit body (22) in a different manner than is depicted in FIG. 1 and FIG. 24 and FIGS. 2-3, and the contoured cutters (82) may consist of or may include other embodiments of contoured cutter (82) as described herein than are depicted in FIG. 1 and FIG. 24 and FIGS. 2-3.
(85) Referring to FIG. 29, an exemplary embodiment of a chamfer for a cutter (60) according to the third aspect of the invention is depicted. The chamfer may be applied to hybrid cutters (80) or to other types of fixed cutter. The chamfer may be applied to all of the edges of a fixed cutter, only to some of the edges of a fixed cutter, and/or only to portions of one or more edges of a fixed cutter.
(86) As depicted in FIG. 29, the cutter (60) is comprised of a cutter element (64) and a substrate (66). The cutter element (64) defines a cutting face (68) and a side (168) adjacent to the cutting face (68). The cutting face (68) has a perimeter (88). The perimeter (88) of the cutting face (68) defines an edge between the cutting face (68) and the side (168) of the cutter element (64).
(87) At least a portion of the edge is chamfered to provide a transition between the cutting face (68) and the side (168) of the cutter element (64). The chamfer is comprised of a side bevel (180) and a cutting face bevel (182). The side bevel (180) has a side bevel length and the cutting face bevel (182) has a cutting face bevel length.
(88) In the third aspect of the invention, the cutting face bevel length is at least two times the side bevel length. In some embodiments of the third aspect, the side bevel length is less than about 0.3 millimeters (about 0.012 inches).
(89) In some embodiments of the third aspect, the chamfer of the invention may be subjected to finish grinding or to some other finishing procedure or procedures to enhance the performance of the cutter (60) and/or the chamfer. In some embodiments of the third aspect, the finish grinding may be comprised of providing a micro bevel or a round to the angles between the cutting face (68), the side (168) and/or the bevels (180, 182).
(90) In this document, the word comprising is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article a does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements.
