Smith International, Inc.

Other

James Carl Minikus

Chris Edward Cawthorne

Gary Ray Portwood

Gary Edward Garcia

Dennis Cisneros

Scott D McDonough

Per Ivar Nese

Michael Allen Siracki

David P Moran

Stephen C Steinke

Quan V Nguyen

Madapusi K Keshavan

Zhigang Zak Fang

Amardeep Singh

Dah-Ben Liang

Jiinjen Albert Sue

Jonathan Bitler

Ying Xiang

Brandon M Moss

A drill bit for cutting a borehole comprises a bit body. In addition, the drill bit comprises a rolling cone cutter mounted on the bit body and adapted for rotation about a cone axis. Further, the drill bit comprises at least one insert having a base portion secured in the rolling cone cutter and a cutting portion extending therefrom. The cutting portion includes a pair of flanking surfaces that taper towards one another to form an elongate chisel crest including a first crest end, a second crest end, and an apex positioned therebetween. A transverse radius of curvature at the first crest end is less than a transverse radius of curvature at the apex, and a transverse radius of curvature at the second crest end is less than the transverse radius of curvature at the apex.

Rock bit and inserts with a chisel crest having a broadened region

Cutting elements offering increased toughness and thermal fatigue resistance can be formed of a wear resistant material having coarse grains disposed in a binder matrix with a binder content of at least about 18% by weight. The coarse grains include grains of at least one selected from the group of a transition metal carbide, a transition metal boride, and transition metal nitride. The binder content and coarse grain size may be selected to provide a Rockwell A hardness of at least about 75 Ra or a wear number of at least about 1.5.

Cutting elements with increased toughness and thermal fatigue resistance for drilling applications

A cutter element for a drill bit has a crest that defines a crest line. The crest can be non-rectilinear. The crest line of each cutter element defines an angle with respect to the axis of the rolling cone on which the cutter element is mounted. The cutter elements define different angles with respect to the cone axis and with respect to each other.

Cutter element with non-linear, expanded crest

An earth-boring bit for drilling a borehole comprises a bit body having a bit axis, at least two rolling cone cutters rotatably mounted on the bit body, a plurality of inner row cutter elements positioned on at least one cone cutter in a first inner row, a plurality of gage-cutting cutter elements positioned in a first fanned-gage row on a first one of the one cutters, and a plurality of gage-cutting cutter elements positioned in a second fanned-gage row on a second one of the one cutters, wherein the gage-cutting cutter elements on the bit define a gage curve and cutter elements in the first fanned-gage row and the second fanned-gage row contact the gage curve at different points. In one embodiment, each cutter element has an extension, and the extensions of the uppermost fanned-gage row cutter element and the first inner row cutter element define a step distance such that the ratio of the step distance to the extension of the first inner row cutter element is greater than 0.5. Alternatively, the first and second fanned-gage rows are positioned to have different oversize angles, positioned such that the ratio of the diameter of the largest fanned-gage row cutter element to the diameter of the first inner row cutter elements is not greater than 0.75, or positioned such that the lowermost fanned-gage row contains more cutter elements than any other fanned-gage row.

Rolling cone bit with elements fanned along the gage curve

A cutter element for a drill bit has a non-rectilinear crest. The cutter element has a base portion and an extending portion and the extending portion has either a zero draft or a negative draft with respect to the base portion. The non-positive draft allows more of the borehole bottom to be scraped using fewer cutter elements. The cutter elements having non-positive draft can be either tungsten carbide inserts or steel teeth.

A rolling cone bit includes at least one cone cutter having a gage row of cutter elements and a first inner row of near but off-gage cutter elements that are positioned so as to divide the sidewall and bottom hole cutting duty so as to enhance bit durability, maintain borehole diameter and improve ROP. The off-gage distance of the first inner row of cutter elements is defined for various bit sizes to optimize the division of cutting duty. The distance that the first inner row of cutter elements are off-gage may be constant for all the cones on the bit or may be varied among the various cones to balance the durability and wear characteristics on all the cones of the bit.

Rolling cone bit with gage and off-gage cutter elements positioned to separate sidewall and bottom hole cutting duty

A cutter element for a drill bit. The cutter element has a non-rectilinear crest. The non-rectilinear or curvilinear crest provides an advantageous distribution of the cutting forces across the body of the cutter elements and thus improves bit life. The curvilinear crest also allows the cutter element to more efficiently lift the portion of the formation that is being cut, thereby improving cutting action in certain formations. The cutter elements can have either positive or non-positive draft and can be tungsten carbide inserts.

Cutter element with non-rectilinear crest

A cutter element that balances maximum gage-keeping capabilities with minimal tensile stress induced damage to the cutter elements is disclosed. The cutter elements of the present invention have a non-symmetrical shape and may include a more aggressive cutting profile than conventional cutter elements. In one embodiment, a cutter element is configured such that the inside angle at which its leading face intersects the wear face is less than the inside angle at which its trailing face intersects the wear face. This can also be accomplished by providing the cutter element with a relieved wear face. In another embodiment of the invention, the surfaces of the present cutter element are curvilinear and the transitions between the leading and trailing faces and the gage face are rounded, or contoured. In this embodiment, the leading transition is made sharper than the trailing transition by configuring it such that the leading transition has a smaller radius of curvature than the radius of curvature of the trailing transition. In another embodiment, the cutter element has a chamfered trailing edge such that the leading transition of the cutter element is sharper than its trailing transition. In another embodiment, the cutter element has a chamfered or contoured trailing edge in combination with a canted wear face. In still another embodiment, the cutter element includes a positive rake angle on its leading edge.

Non-symmetrical stress-resistant rotary drill bit cutter element

A steel tooth particularly suited for use in a rolling cone bit includes a parent metal core having an inner gage facing surface, leading and trailing edges, a root region adjacent to the cone and an outer most edge spaced from the root region. A hardfacing layer that includes at least two hardfacing materials having differing wear characteristics is disposed over the parent metal core in an asymmetric arrangement of regions of the first and second materials. A first of the hardfacing materials has a higher low stress abrasive wear resistance than that of the second material. The second material has a high stress abrasion resistance that is greater than the first material. The first and second materials are applied in generally contiguous regions over the entire gage facing surface of the parent metal core so as to optimize regions of the tooth for the particular cutting duty experience by that region.

Hardfacing on steel tooth cutter element

A rolling cone bit includes a cone cutter having a gage row and an adjacent nestled gage row of cutter elements that are positioned on gage so as to divide or share the borehole corner cutting duty. The wear resistance, hardness, toughness and shape of the cutter elements in the adjacent rows are optimized depending upon the type of cutting the respective rows perform, the characteristics of the formation being drilled and the drilling techniques being employed. In most applications, the nestled gage cutter elements will have cutting surfaces that are more wear resistant or harder than the cutting surfaces of the gage cutter elements which experience more bottom hole duty. The nestled gage cutter elements engage the borehole wall with a negative rake angle for increased durability. Preferably, the nestled gage cutter elements have continuously contoured and non-shearing cutting surfaces.

Rolling cone bit having gage and nestled gage cutter elements having

A steel tooth, particularly suited for use in a rolling cone bit, includes a root region, a cutting tip spaced from the root region and a gage facing surface therebetween. The gage facing surface includes a knee, and is configured such that the cutting tip is maintained at a position off the gage curve. So positioned, the cutting tip is freed from having to perform any substantial cutting duty in the corner on the borehole corner, and instead may be configured and optimized for bottom hole cutting duty. The knee on the gage facing surface is configured and positioned so as to serve primarily to cut the borehole wall. It is preferred that the knee be positioned off gage, but that it be closer to the gage curve than the cutting tip.

Steel tooth cutter element with gage facing knee

A steel tooth bit includes one or more rolling cone cutters having a generally conical surface, a heel surface, and preferably a transition surface therebetween. A row of gage cutter elements are secured to the cone cutter on the transition surface and have cutting surfaces that cut to full gage. A first inner row of off-gage steel teeth is positioned on the conical surface of the cone cutter so that the gage-facing cutting surfaces of the teeth are close to gage, but are preferably off-gage a distance D at a knee that is formed on the gage facing surface. Distance D is strategically selected such that the gage and off-gage cutter elements cooperatively cut the corner of the borehole. The lower most portion of the gage facing surface of these steel teeth are off gage a distance D' which is greater than D so as to bring the cutting tip of the teeth off gage to prevent undesired wear and rounding off of the tip of the cutter element. The upper most portion of the gage-facing surface is also preferably off gage a distance D' that is greater than D so as to optimize the surface area on the gage facing surface that is in contact with the borehole corner.

Rolling cone steel tooth bit with enhancements in cutter shape and

A rolling cone bit includes a cone cutter having a pair of adjacent rows of cutter elements that are positioned so as to divide the sidewall and bottom hole cutting duty. The wear resistance, hardness and toughness of the cutter elements in the adjacent rows are optimized depending upon the type of cutting the respective rows perform. In most applications, the cutter elements experiencing more sidewall cutting will have cutting surfaces that are more wear resistant or harder than the cutting surfaces of cutter elements in rows experiencing more bottom hole duty. Likewise, the cutter elements exposed to more bottom hole duty will generally be tougher than those experiencing substantial sidewall cutting. The material enhancements include varying the grades of tungsten carbide used in the cutter elements and by selectively employing layers of super abrasives, such as PCD or PCBN. The cutter elements may be either inserts or steel teeth.

Rolling cone bit with enhancements in cutter element placement and

A chisel type insert is disclosed having a contoured surface in which the vertical lines located on the surface are bowed outwardly in a convex manner thereby eliminating blend radii from the cutting tip and the high stress concentrations associated therewith.

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Spring, TX, United States of America

James Carl Minikus