DRILL BIT HAVING SHEAR AND PICK-TYPE CUTTERS
A drill bit includes a bit body defining a plurality of blades extending from a selected distance from an axis of rotation of the bit body to a gage face. A plurality of only gouging cutters is mounted on the bit body. At least one of the plurality of blades has a blade top surface longitudinally behind the tips of the gouging cutters at a selected distance from the tips of the gouging cutters.
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BACKGROUNDThis disclosure relates generally to the field of fixed cutter drill bits. More specifically, the disclosure relates to drill bits having both shear cutters and “gouging” type cutters.
Fixed cutter bits known in the art include PDC bits, wherein a plurality of PDC cutters are affixed to a bit body in a selected arrangement on one or more blades formed in the bit body.
Gouging type cutters are used in drill bits for drilling mine shafts or tunnels, among other uses. Such bits are known in the art as “claw” bits, one example of which is sold under the trademark QUI-KLAW, which is a trademark of Drillhead, Inc. Such bits are known to be useful in drilling clay, unconsolidated sand, loose rock and gravel.
U.S. Pat. No. 8,505,634 issued to Lyons et al. describes a drill bit having gouging cutting elements disposed adjacent to shearing cutting elements on a blade on the bit body. The shearing cutting elements have a planar cutting face, while the gouging cutting elements have a non-planar cutting face, e.g., dome shaped or cone shaped.
SUMMARYA drill bit according to one aspect of the disclosure includes a bit body defining a plurality of blades extending from a selected distance from an axis of rotation of the bit body to a gage face. A plurality of only gouging cutters is mounted on the bit body. At least one of the plurality of blades has a blade top surface longitudinally behind the tips of the gouging cutters at a selected distance from the tips of the gouging cutters.
Other aspects and advantages will be apparent from the description and claims that follow.
An example drill bit according to the present disclosure is shown in oblique view at 10 in
At least one or each blade 12 may define a stepped, dual “profile” or curved shape. In the present example, a forward (with respect to direction of rotation of the bit) step of at least one or all of the blades 12 may be longitudinally lower or behind (further back or rearward with respect to the direction the bit will drill) than a rearward step of blade 12, as will be further explained below with reference to
The shear cutters 16 may be mounted on the blade 12 at a selected backrake angle. In the present example, the backrake angle may be about 20 degrees with respect to a plane parallel to the axis of rotation of the bit. A range of backrake angles within about 10 to 30 degrees is within the scope of the present disclosure. The gouging cutters 18 may be mounted in openings (
A space between circumferentially adjacent blades 12 may form a flow path or waterway to enable space for cuttings generated by the bit 10 to be disposed until they are forced out by the action of drilling fluid pumped through one or more nozzles or “jets” 20 inserted into the bit body 11 as shown in
In the present example drill bit, shear cutters are used, as shown in
In other examples, the rearward step 24 may omit the mounting pockets 16A and the shear cutters (16 in
In some examples, the blades (12 in
An example shear cutter 16 is shown in side view in
The cutter body 34 may taper toward a cutter tip 36. The cutter tip 36 may be substantially ballistically shaped and made from a hard or superhard material, e.g., tungsten carbide, diamond impregnated tungsten carbide, cubic boron nitride, polycrystalline diamond or other hard or superhard material. The gouging cutter 18 may be removed from the pocket 18A at any convenient location, where the bit (10 in
In other examples, gouging cutters may be mounted on one or more blades and shear cutters may be mounted on one or more blades. In such examples, as in the other examples described above, the gouging cutters and shear cutters may be affixed to the blades within the stated respective ranges of rake angles, and the gouging cutters may extend longitudinally ahead of the cutting surface defined by the shear cutters by the distances described above.
In the examples of
Drill bits made according to the present disclosure have demonstrated ability to drill through vary coarse, unconsolidated sediments, with rock fragments in the centimeter size range, substantially without failure of either the gouging cutters or the shear cutters.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims
1-19. (canceled)
20. A drill bit, comprising:
- a bit body having a plurality of only gouging cutters mounted on the bit body; and
- means for limiting cutting depth of the gouging cutters to a selected distance longitudinally behind tips of the gouging cutters.
21. The bit of claim 20 further comprising a plurality of blades extending from a selected distance from an axis of rotation of the bit body to a gage face, wherein a blade top surface of each of the plurality of blades defines the means for limiting cutting depth.
22. The bit of claim 21 wherein at least one of the plurality of blades further comprises a plurality of shear cutters affixed thereon, and wherein the gouging cutters extend a selected distance longitudinally ahead of a cutting surface defined by the shear cutters, the gouging cutters mounted on at least one of the bit body or on a surface of at least one of the plurality of blades.
23. The bit of claim 22 wherein the gouging cutters are mounted to the bit body rotationally ahead of the shear cutters.
24. The bit of claim 22 wherein the gouging cutters are mounted to the bit body rotationally behind the shear cutters.
25. The bit of claim 22 wherein the shear cutters comprise at least one of polycrystalline diamond compact cutters, tungsten carbide cutters, diamond impregnated tungsten carbide cutters and cubic boron nitride cutters.
26. The bit of claim 22 wherein the shear cutters are disposed at a backrake angle in a range of 10 to 30 degrees.
27. The bit of claim 22 wherein the shear cutters are disposed at a backrake angle of about 20 degrees.
28. The bit of claim 22 wherein the selected longitudinal extension of the gouging cutters is within a range of ⅛ inch (3 millimeters) to ¾ inch (19 millimeters) beyond the defined cutting surface.
29. The bit of claim 28 wherein the selected longitudinal extension of the gouging cutters is about 0.5 inches (13 millimeters) beyond the defined cutting surface.
30. The bit of claim 20 wherein the gouging cutters comprise a steel body and a tip made from at least one of tungsten carbide, diamond impregnated tungsten carbide, polycrystalline diamond and cubic boron nitride.
31. The bit of claim 20 wherein the gouging cutters are disposed at a forward rake angle in a range of 15 to 45 degrees.
32. The bit of claim 31 wherein the forward rake angle of the gouging cutters is about 15 degrees.
33. The bit of claim 20 wherein a selected longitudinal extension of the gouging cutters is within a range of ⅛ inch (3 millimeters) to ¾ inch (19 millimeters) beyond the means for limiting cutting depth.
34. The bit of claim 33 wherein the selected longitudinal extension of the gouging cutters is about 0.5 inches (13 millimeters).
35. The bit of claim 20 further comprising at least one gage insert in the gage face of each of the blades.
36. The bit of claim 35 wherein the gage inserts comprise at least one of polycrystalline diamond, cubic boron nitride, diamond impregnated tungsten carbide and tungsten carbide.
37. The bit of claim 20 wherein the gouging cutters are rotatably mounted on the bit body.
38. The bit of claim 20 wherein the gouging cutters are removably mounted on the bit body.
39. The bit of claim 38 wherein each of the gouging cutters is locked into the bit body by a snap ring.
Type: Application
Filed: Sep 4, 2013
Publication Date: Mar 5, 2015
Applicant: Shear Bits, Ltd. (Calgary)
Inventors: John James Herman (Cypress County), Dallas Wilkins (Calgary), Ryan J. C. Marley (Airdrie), Timothy P. Beaton (Calgary)
Application Number: 14/018,339
International Classification: E21B 10/567 (20060101); E21B 10/08 (20060101);