Patent Application
20120111638
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1. Field of the Invention
The present inventions relate in general to earth-boring drill bits and, in particular, to a bit having a combination of rolling and fixed cutters and cutting elements and a method of drilling with same.
2. Description of the Related Art
U.S. Pat. No. 3,294,186 discloses the use of nickel shims for brazing of rock bit components.
U.S. Pat. No. 3,907,191 discloses a “rotary rock bit is constructed from a multiplicity of individual segments. Each individual segment includes two parting faces and a gage cutting surface. The individual segments are positioned adjacent each other with the parting faces of the adjacent segments in abutting relationship to one another. A ring gage is positioned around the segments and the individual segments are moved relative to one another causing the parting faces of an individual segment to slide against the parting faces of the adjacent segments. The segments are moved until the gage cutting surfaces of the segments contact the ring gage thereby insuring that the finished bit will have the desired gage size. The segments are welded together over a substantial portion of the parting faces.”
U.S. Pat. No. 5,439,067 discloses a “rotary cone drill bit for forming a borehole having a one-piece bit body with a lower portion having a convex exterior surface and an upper portion adapted for connection to a drill string. A number of support arms are preferably attached to the bit body and depend therefrom. Each support arm has an inside surface with a spindle connected thereto and an outer surface. Each spindle projects generally downwardly and inwardly with respect to the associated support arm. A number of cone cutter assemblies equal to the number of support arms are mounted on each of the spindles. The support arms are spaced on the exterior of the bit body to provide enhanced fluid flow between the lower portion of the bit body and the support arms. Also, the length of the support arms is selected to provide enhanced fluid flow between the associated cutter cone assembly and the lower portion of the bit body. The same bit body may be used with various rotary cone drill bits having different gauge diameters.”
U.S. Pat. No. 5,439,068 discloses a “rotary cone drill bit for forming a borehole having a one-piece bit body with a lower portion having a convex exterior surface and an upper portion adapted for connection to a drill string. The drill bit will generally rotate around a central axis of the bit body. A number of support arms are preferably attached to pockets formed in the bit body and depend therefrom. Each support arm has an inside surface with a spindle connected thereto and an outer surface. Each spindle projects generally downwardly and inwardly with respect to the longitudinal axis of the associated support arm and the central axis of the bit body. A number of cone cutter assemblies equal to the number of support arms are mounted respectively on each of the spindles. The spacing between each of the support arms along with their respective length and width dimensions are selected to enhance fluid flow between the cutter cone assemblies mounted on the respective support arms and the lower portion of the bit body. A lubricant reservoir is preferably provided in each support arm to supply lubricant to one or more bearing assemblies disposed between each cutter cone assembly and its associated spindle. Either matching openings and posts or matching keyways and keys may be used to position and align a portion of each support arm within its associated pocket during fabrication of the resulting drill bit.
U.S. Pat. No. 5,595,255 discloses a “rotary cone drill bit for forming a borehole having a bit body with an upper end portion adapted for connection to a drill string. The drill bit rotates around a central axis of the body. A number of support arms are preferably extend from the bit body. The support arms may either be formed as an integral part of the bit body or attached to the exterior of the bit body in pockets sized to receive the associated support arm. Each support arm has a lower portion with an inside surface and a spindle connected thereto and an outer shirttail surface. Each spindle projects generally downwardly and inwardly with respect to its associated support arm. A number of cutter cone assemblies equal to the number of support arms are mounted respectively on the spindles. A throat relief area is provided on the lower portion of each support arm adjacent to the associated spindle to increase fluid flow between the support arm and the respective cutter cone assembly.”
U.S. Pat. No. 5,606,895 discloses a “rotary cone drill bit having a one-piece bit body with a lower portion having a convex exterior surface and an upper portion adapted for connection to a drill string. The drill bit will generally rotate around a central axis of the bit body to form a borehole. A number of support arms are preferably attached to pockets formed in the bit body and depend therefrom. The bit body and support arms cooperate with each other to reduce initial manufacturing costs and to allow rebuilding of a worn drill bit. Each support arm has an inside surface with a spindle connected thereto and an outer shirttail surface. Each spindle projects generally downwardly and inwardly with respect to the longitudinal axis of the associated support arm and the central axis of the bit body. A number of cone cutter assemblies equal to the number of support arms are mounted respectively on each of the spindles. The radial spacing of the support arms on the perimeter of the associated bit body along with their respective length and width dimensions are selected to enhance fluid flow between the cutter cone assemblies mounted on the respective support arms and the lower portion of the bit body. The resulting drill bit provides enhanced fluid flow, increased seal and bearing life, improved downhole performance and standardization of manufacturing and design procedures.”
U.S. Pat. No. 5,624,002 discloses a “rotary cone drill bit having a one-piece bit body with a lower portion having a convex exterior surface and an upper portion adapted for connection to a drill string. The drill bit will generally rotate around a central axis of the bit body to form a borehole. A number of support arms are preferably attached to pockets formed in the bit body and depend therefrom. The bit body and support arms cooperate with each other to reduce initial manufacturing costs and to allow rebuilding of a worn drill bit. Each support arm has an inside surface with a spindle connected thereto and an outer shirttail surface. Each spindle projects generally downwardly and inwardly with respect to the longitudinal axis of the associated support arm and the central axis of the bit body. A number of cone cutter assemblies equal to the number of support arms are mounted respectively on each of the spindles. The radial spacing of the support arms on the perimeter of the associated bit body along with their respective length and width dimensions are selected to enhance fluid flow between the cutter cone assemblies mounted on the respective support arms and the lower portion of the bit body. The resulting drill bit provides enhanced fluid flow, increased seal and bearing life, improved downhole performance and standardization of manufacturing and design procedures.”
U.S. Design Pat. No. D372,253 shows a support arm and rotary cone for modular drill bit.
The inventions disclosed and taught herein are directed to an improved hybrid bit having a combination of rolling and fixed cutters and cutting elements.
The inventions disclosed and taught herein are directed to an earth boring drill bit designed for a specific performance, within a finished product tolerance, using components built to a looser manufacturing tolerance, and a method of assembling the bit. The bit may be assembled by selecting one or more legs from a plurality of pre-manufactured legs; selecting a bit body from a plurality of pre-manufactured bit bodies, the bit body having a slot for receiving the leg; placing the leg within the slot; and fixing the leg within the slot within the finished product tolerance by placing one or more shims between the leg and the slot. The leg and shims may be welded or bolted into the bit body. The number and/or thickness of the shims may be selected to bring the earth boring drill bit within the finished product tolerance. The shims may be used to adjust an axial position, a radial position, and/or circumferential position of the leg with respect to the slot, thereby adjusting the position of roller cone cutting elements associated with the leg with respect to fixed cutting elements secured to a blade of the bit body. The leg and the bit body may be selected, or produced, such that the leg will not fill the slot. For example, the bit body may be manufactured to ensure the bit will not meet the specification, given the manufacturing tolerance, without the shims. Additionally, or alternatively, the leg may be manufactured to ensure the leg will not meet the performance specification, given the manufacturing tolerance, without the shims.
The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicants have invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present inventions will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of skill in this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. Lastly, the use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims.
Applicants have created an earth boring drill bit designed for a specific performance, within a finished product tolerance, using components built to a looser manufacturing tolerance, and a method of assembling the bit. The bit may be assembled by selecting one or more legs from a plurality of pre-manufactured legs; selecting a bit body from a plurality of pre-manufactured bit bodies, the bit body having a slot for receiving the leg; placing the leg within the slot; and fixing the leg within the slot within the finished product tolerance by placing one or more shims between the leg and the slot. The leg and shims may be welded or bolted into the bit body. The number and/or thickness of the shims may be selected to bring the earth boring drill bit within the finished product tolerance. The shims may be used to adjust an axial position, a radial position, and/or circumferential position of the leg with respect to the slot, thereby adjusting the position of roller cone cutting elements associated with the leg with respect to fixed cutting elements secured to a blade of the bit body. The leg and the bit body may be selected, or produced, such that the leg will not fill the slot. For example, the bit body may be manufactured to ensure the bit will not meet the specification, given the manufacturing tolerance, without the shims. Additionally, or alternatively, the leg may be manufactured to ensure the leg will not meet the performance specification, given the manufacturing tolerance, without the shims.
Referring to
Rolling cutters 21 are mounted to respective ones of the bit legs 17. Each of the rolling cutters 21 is shaped and located such that every surface of the rolling cutters 21 is radially spaced apart from the axial center 15 by a minimal radial distance 23. A plurality of rolling-cutter cutting inserts or elements 25 are mounted to the rolling cutters 21 and radially spaced apart from the axial center 15 by a minimal radial distance 27. The minimal radial distances 23, 27 may vary according to the application, and may vary from cutter to cutter, and/or cutting element to cutting element.
In addition, a plurality of fixed cutting elements 31 are mounted to the fixed blades 19. At least one of the fixed cutting elements 31 may be located at the axial center 15 of the bit body 13 and adapted to cut a formation at the axial center. In one embodiment, the at least one of the fixed cutting elements 31 is within approximately 0.040 inches of the axial center. Examples of rolling-cutter cutting elements 25 and fixed cutting elements 31 include tungsten carbide inserts, cutters made of super-hard material such as polycrystalline diamond, and others known to those skilled in the art.
As illustrated, bit 111 comprises a shank portion or section 113, which is threaded or otherwise configured at its upper extent for connection into a drillstring. At the lower extent of shank portion 113, a generally cylindrical receptacle 115 is formed. Receptacle 115 receives a correspondingly shaped and dimensioned cylindrical portion 117 at the upper extent of a bit body portion 119. Shank 113 and body 119 portions are joined together by inserting the cylindrical portion 117 at the upper extent of body portion 119 into the cylindrical receptacle 115 in the lower extent of shank 113. For the 12¼ inch bit shown, the receptacle is a Class 2 female thread that engages with a mating male thread at the upper extent of the body. The circular seam or joint is then continuously bead welded to secure the two portions or sections together. Receptacle 115 and upper extent 117 need not be cylindrical, but could be other shapes that mate together, or could be a sliding or running fit relying on the weld for strength. Alternatively, the joint could be strengthened by a close interference fit between upper extent 119 and receptacle 115. Tack welding around, and/or fully welding, the seam could also be used.
A bit leg or head 121 (three are shown for the three-cutter embodiment of
As shown in
Thus, the roller cone cutting elements 25 and the fixed cutting elements 31 combine to define a common cutting face 51 (
For example, assuming the fixed cutting elements 31 are fixed due to the integration of the blades 19 with the bit body 13, one may wish to manipulate the axial and/or radial position of the legs 17, thereby controlling the axial and/or radial position of the roller cone cutting elements 25 with respect to the fixed cutting elements 31 and/or the cutting profile 41. As shown in
More specifically, one or more shims 200 may be placed in any or all of the slots 123 between the leg 17 and an axial wall 150 of the slot 123 in the bit body 13 to adjust the axial position of the roller cone cutting elements 25 with respect to the fixed cutting elements 31 and/or the cutting profile 41, as shown in
The shims 200 may have two parallel opposing surfaces, as shown, such that the leg 17 is positioned substantially parallel to the bit body 13, axis 15, and/or the walls 150,155 of the slot 123. Alternatively, the opposing surfaces may be convergent and/or divergent along the length of the shim 200, such that an angle between the leg 17 and the bit body 13, axis 15, and/or the walls 150,155 of the slot 123 may be manipulated. The shims 200 preferably extend the entire length of the walls 135,150,155,160 of the slot 123, but may be longer or shorter, as desired.
The shims 200 are preferably between 0.003 and 0.005 inches thick. However, the shims 200 may be between 0.003 and 0.015 inches thick. For example, the shims 200 may be between 0.005 and 0.015 inches thick. Alternatively, the shims 200 may be between 0.010 and 0.015 inches thick.
The shims 200 may also include apertures, such as those in leg 121 through which bolts 127 extend. The apertures may be oblong to allow adjustment of their position relative to the bolts 127. Alternatively, the apertures may be circular, thereby fixing their position relative to the bolts 127. In this case, the shims 200 may be fixed with respect to the bit body 13, but still allow the legs 17 to move relative thereto.
Furthermore, rather than the legs 16 being bolted to the body 13, the legs 17 may be welded, brazed, or otherwise fixedly secured to the bit body 13. In this case, the shims 200 may act as filler and included in the welding, brazing, or other process. In some embodiments, each shim 200 may be individually welded in place, one after another and/or on top of another, as needed, with the leg 17 thereafter being welded to the shims 200 and/or weld bead built up with the shims 200.
In any case, it can be seen how the shims 200 may be used to accommodate relatively loose manufacturing tolerances, and still allow the finished bit 11 to meet relatively tight finished product tolerances. This is done by selecting the number and/or thickness of shim(s) 200 necessary to meet a given finished product tolerance, with parts made to virtually any manufacturing tolerances. To further ensure this capability, the slots 123 may be oversized, i.e. larger, wider, and/or deeper than ultimately desired, and the legs 17 may be undersized, i.e. smaller, narrower, and/or shallower than ultimately desired, thereby allowing the excess space to be occupied, or made up, by more and/or thicker shims 200.
The shims 200 allow adjustment of the axial position, radial position, and/or circumferential position up to approximately one tenth of an inch, or even one eighth of an inch. For example, using current manufacturing capabilities, most bits appear to need between 0.020 and 0.030 inches of adjustment. However, other ranges of adjustment are contemplated, such as between 0.010 and 0.075 inches of adjustment, between 0.020 and 0.030 inches of adjustment, between 0.010 and 0.050 inches of adjustment, between 0.020 and 0.050 inches of adjustment, or between 0.015 and 0.030 inches of adjustment. Furthermore, one bit 11 may require difference ranges of adjustment of each position, such that the axial position is adjusted a different amount than the circumferential position, etc.
In this manner, as shown in
The use of the shims 200 also allows preassembly of multiple bits without the need of expensive and complex jigs to hold the assembled bit while waiting to be welded. In this regard, the legs 17, with shims 200, may be assembled and then bolted together and/or tack welded before final welding occurs.
Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of the invention. For example, the shims 200 may also be used along any of the walls of the slots 123, to accommodate independent adjustment of the axial position, radial position, or circumferential position, or any combination thereof. Further, the various methods and embodiments of the present invention can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa.
The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions.
The inventions have been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intend to fully protect all such modifications and improvements that come within the scope or range of equivalent of the following claims.
