GB2300437A - Cutting elements for rotary drill bits - Google Patents
Cutting elements for rotary drill bits Download PDFInfo
- Publication number
- GB2300437A GB2300437A GB9608172A GB9608172A GB2300437A GB 2300437 A GB2300437 A GB 2300437A GB 9608172 A GB9608172 A GB 9608172A GB 9608172 A GB9608172 A GB 9608172A GB 2300437 A GB2300437 A GB 2300437A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cutting element
- peripheral surface
- element according
- substrate
- chamfer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000002093 peripheral effect Effects 0.000 claims abstract description 42
- 239000000758 substrate Substances 0.000 claims abstract description 30
- 239000000463 material Substances 0.000 claims abstract description 20
- 230000007704 transition Effects 0.000 claims abstract description 15
- 230000000875 corresponding effect Effects 0.000 claims 1
- 229910003460 diamond Inorganic materials 0.000 abstract description 9
- 239000010432 diamond Substances 0.000 abstract description 9
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 abstract description 7
- 238000004901 spalling Methods 0.000 abstract description 5
- 230000015572 biosynthetic process Effects 0.000 description 8
- 238000005755 formation reaction Methods 0.000 description 8
- 238000005553 drilling Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 238000007493 shaping process Methods 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910052582 BN Inorganic materials 0.000 description 1
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 230000032798 delamination Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B10/00—Drill bits
- E21B10/46—Drill bits characterised by wear resisting parts, e.g. diamond inserts
- E21B10/56—Button-type inserts
- E21B10/567—Button-type inserts with preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts
- E21B10/5673—Button-type inserts with preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts having a non planar or non circular cutting face
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Geology (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Drilling Tools (AREA)
- Earth Drilling (AREA)
Abstract
A preform cutting element for a rotary drag-type drill bit includes a facing table 32 of superhard material bonded to a less hard substrate 33, the peripheral surface of the facing table including a substantially straight cutting edge 35, at least one end of which has a chamfer 36 providing a transition at the junction 37 between the end of the cutting edge and the remainder of the peripheral surface. The chamfer may be smoothly curved or in the form of a part circular arc radius of curvature r. Both ends of the cutting edge 35 may be chamfered. The smooth transition may reduce the spalling or other damage which may be caused by steady state and impact loads in this region. The facing table may be polycrystalline diamond and the substrate may be tungsten carbide.
Description
"Improvements in or relating to cutting elements for rotary drill bits"
The invention relates to cutting elements for rotary drill bits and particularly to preform cutting elements for use in rotary drag-type drill bits for drilling or coring holes in subsurface formations. The preform elements are of the kind comprising a facing table of superhard material having a front face, a peripheral surface, and a rear surface bonded to a substrate of material which is less hard than the superhard material.
The facing table is usually formed from polycrystalline diamond, although other superhard materials are available, such as cubic boron nitride. The substrate of less hard material is often formed from cemented tungsten carbide, and the facing table and substrate are bonded together during formation of the element in a high pressure, high temperature forming press. This forming process is well known and will not be described in detail.
Each preform cutting element may be mounted on a carrier in the form of a generally cylindrical stud or post received in a socket in the body of the drill bit. The carrier is often formed from cemented tungsten carbide, the rear surface of the substrate being brazed to a surface on the carrier, for example by a process known as "LS bonding". Alternatively, the substrate itself may be of sufficient thickness to provide, in effect, a cylindrical stud which is sufficiently long to be directly received in a socket in the bit body, without being brazed to a carrier. The bit body itself may be machined from metal, usually steel, or may be moulded using a powder metallurgy process.
In one common form of drill bit, the operative end face of the bit body is formed with a number of blades radiating from the central area of the bit, the blades carrying cutting elements spaced apart along the length thereof. The bit also has a gauge section including kickers which contact walls ofthe borehole to stabilise the bit in the borehole.
It is common practice to mount on the bit body, in the intermediate region where the kickers meet the blades, so called gauge cutters the purpose of which is to cut and form the side walls of the borehole as the cutting elements on the blades cut into the bottom of the borehole and the drill bit progresses downwardly.
The cutting elements mounted on the blades on the end face of the bit body are commonly initially circular so as to provide a part-circular cutting edge to engage the formation at the bottom of the borehole. Gauge cutters, however, commonly have a substantially straight cutting edge which, in use, extends generally parallel to the longitudinal rotational axis of the drill bit so as to cut the side walls of a cylindrical borehole.
All such cutting elements are subjected to extremes of temperature during formation and mounting on the bit body, and are also subjected to high temperatures and heavy loads, such as impact loads, when the drill is in use down a borehole. It is found that as a result of such conditions spalling and delamination of the superhard facing table can occur, that is to say the separation and loss of the diamond or other superhard material over the cutting surface of the table. The present invention sets out to provide a novel form of preform cutting element, particularly suitable for use as a gauge cutter, which may be less susceptible than prior art gauge cutters to such spalling and other forms of damage.
According to the invention there is provided a preform cutting element for a rotary drag-type drill bit including a facing table of superhard material having a front face, a peripheral surface, and a rear surface bonded to a substrate of a material which is less hard than the superhard material, the peripheral surface of the cutting element including a substantially straight cutting edge having at opposite ends thereofjunctions with the remainder of said peripheral surface, at least one of said junctions being formed with a chamfer which provides a transition between the end of the cutting edge and the adjacent portion of the remainder of the peripheral surface of the cutting element.
In some cases both junctions may be chamfered.
Although said transition chamfer may be angled, preferably the chamfer is smoothly curved to provide a continuous transition between the end of the cutting edge and the adjacent portion of the remainder of the peripheral surface. For example, the chamfer may be in the form of a part-circular arc, opposite ends of which are substantially tangential to the cutting edge and the remainder of the peripheral surface respectively. In the case where both junctions are in the form of part-circular arcs, the arcs may be of the same, or different, radii.
It is considered that the chamfering of one or both junctions between the cutting edge and the remainder of the peripheral surface may reduce the high contact loading, both steady state and impact loads, which may occur at these locations, and thus reduce the spalling or other damage which may be initiated or caused by such loads.
In a preferred embodiment of the invention, the remainder of the peripheral surface of the cutting element is part-circular. Said part-circular portion of the peripheral surface preferably has an angular extent which is greater than 1800, for example it may be in the range of 210 -270 .
In the case where the chamfer is in the form of a part-circular arc, and said remainder of the peripheral surface of the cutting element is part-circular, the ratio of the radius of curvature of the chamfer to the radius of curvature of the peripheral surface may be in the range of 1:1.4 to 1:1.8.
For example, if the radius of curvature of the peripheral surface is 6.5mm, the radius of curvature of the chamfer may be about 4mm, and if the radius of curvature of the peripheral surface is 9.5mm the radius of curvature of the chamfer may be about 6.5mm. Cutters of 4mm and 2.5mm radius are also used, and the invention is applicable to cutters of any size.
The following is a more detailed description of embodiments of the invention, reference being made to the accompanying drawings in which:
Figure 1 is a side elevation of a typical drag-type drill bit in which cutting elements according to the present invention may be used,
Figure 2 is an end elevation of the drill bit shown in Figure 1,
Figure 3 is a plan view of a prior art gauge cutter used in such drill bit,
Figure 4 is a diagrammatic section through the prior art gauge cutter of Figure 3,
Figure 5 is a plan view of a gauge cutter in accordance with the present invention,
Figure 6 is a diagrammatic section through the gauge cutter of Figure 5,
Figure 7 is a plan view of a further form of gauge cutter in accordance with the invention, and
Figure 8 is a side view of the cutter of Figure 7.
Figures 1 and 2 show a typical full bore drag bit of a kind to which the cutting elements of the present invention are applicable. The bit body 10 is machined from steel and has a shank formed with an externally threaded tapered pin 11 at one end for connection to the drill string. The operative end face 12 ofthe bit body is formed with a number of blades 13 radiating from the central area of the bit, and the blades carry cutter assemblies 14 spaced apart along the length thereof. The bit has a gauge section including kickers 16 which contact the walls ofthe borehole to stabilise the bit in the borehole. A central passage (not shown) in the bit and shank delivers drilling fluid through nozzles 17 in the end face 12 in known manner.
Each cutter assembly 14 comprises a preform cutting element 18 mounted on a carrier 19 in the form of a post which is located in a socket in the bit body. Each preform cutting element is the form of a tablet comprising a facing table of superhard material, usually polycrystalline diamond, bonded to a substrate which is normally of cemented tungsten carbide. The rear surface of the substrate is bonded, for example by
LS bonding, to a suitably orientated surface on the post 19.
The cutting elements 18 mounted on the operative end face 12 of the bit body
are commonly initially in the form of circular tablets so as to provide a part-circular cutting edge so that the cutting elements cut concentric grooves in the bottom of the borehole. However, in an intermediate region 20 of the bit body, at the junction between the blades 13 and the kickers 16, the cutter assemblies comprise gauge cutters 21 of a different form. As best seen in Figures 3 and 4, each gauge cutter normally comprises a facing table 22 of polycrystalline diamond or other superhard material bonded to a substrate 23 of a less hard material such as cemented tungsten carbide. The gauge cutter has a substantially straight cutting edge 24, the remainder of the peripheral surface 25 of the cutting element being part-circular.In use the gauge cutter is orientated on the bit body, in the intermediate region 20, so that the straight cutting edge 24 extends generally parallel to the central longitudinal rotational axis of the drill bit and therefore forms the cylindrical side walls of the borehole as drilling progresses.
In the prior art arrangement the junctions between the opposite ends of the straight cutting edge 24 and the rest ofthe peripheral surface 25 of the cutting element are sharply angled, as indicated at 26 in Figure 3. It is believed that the sharp angling of thesejunctions can lead to stress concentrations at the junctions, when the drill bit is in use, both as a result of steady state loads and also as a result of impact loads of short duration. It is believed that this stress concentration can initiate spalling and other forms of damage to the cutting element resulting in loss of cutting efficiency, or at worst failure, of the cutting element.
Figures 5 and 6 show one improved form of gauge cutting element according to the present invention.
In the arrangement according to the invention the overall shape of the gauge cutting element is generally similar to the prior art arrangement in that it comprises a substantially straight cutting edge 27 and the rest of the peripheral surface 28 of the cutting element is part-circular. However, in accordance with the present invention, the junctions 29 between the opposite ends of the straight cutting edge and the remainder
of the peripheral surface 28 of the cutting element are both chamfered to provide a
gradual transition between the ends of the cutting edge and the peripheral surface so as
to reduce stress concentrations in this region. In the arrangement shown the chamfer is
in the form of a part-circular arc.In the case where the remainder of the peripheral
surface of the cutting element has a radius R of 9.5mum the radius of curvature r of the
chamfer 29 may be about 6.5mm. Similarly, if the radius of curvature R is 6.5mm, the
radius of curvature r ofthe chamfer may be about 4mm. It will be seen that the ends of
the arcuate chamfer are tangential to the cutting edge 27 and the remainder of the
peripheral surface 28 respectively.
As will be seen, the angular extent of the peripheral surface 28 of the cutting
element is greater than 180 , and may for example be in the range of 210"-270".
Instead of both junctions being chamfered, as shown, only one of the junctions
may be chamfered. This is preferably the junction which is lowermost when the bit is drilling downwardly, since this is the junction which is most subject to impact and
damage. The advantage of chamfering only one of the junctions is that it causes less
reduction in the length of the straight cutting edge.
As in the prior art arrangement the cutting element comprises a facing table 30
of polycrystalline diamond, or other superhard material, bonded to a substrate 31 of less
hard material, such as cemented tungsten carbide.
Although the chamfers 29 are preferably in the form of part-circular arcs, other
smoothly curved arrangements may provide similar advantage. Some advantage may also be given by chamfers which are not smoothly curved, for example the junctions may be provided with one or more angled chamfers, but in this case the reduction in stress concentration may be less. The part-circular configuration of the rest of the peripheral surface of the cutting element is shown by way of example only, and it will be appreciated that other shapes of cutting element may be employed.
The cutting edge 27 and chamfers 29 may be formed by shaping an initially circular cutting element. The shaping may, for example, be effected by grinding, EDM or other suitable shaping process. Alternatively, the cutting element may be manufactured to the required shape ab initio in the high pressure, high temperature forming process.
The diamond layer 30, and the substrate 31, may also be chamfered as viewed in crosssection, the chamfer being tangential to the surface of the formation which the cutter engages, so that the part of the cutter rearwards of the cutting edge serves as a buttress to bear some of the radial loads applied to the cutters and drill bit.
Such an arrangement is shown in Figures 7 and 8. In this case the cutter comprises a facing table 32 of polycrystalline diamond bonded to a cylindrical substrate 33 of cemented tungsten carbide. The substrate 33 is of sufficient axial length that it may be directly mounted in a socket in the bit body and does not require to be brazed to a carrier as is the case with thinner cutters.
The diamond facing table 32 is bevelled round its periphery as indicated at 34.
In the present instance the bevel 34 is frusto-conical, but it could equally well be radiused as viewed in cross-section.
As in the previous arrangements the cutter has a substantially straight cutting edge 35. However, in this case the substrate 33 is circular in cross section and the straight cutting edge 35 is formed by forming a flat chamfer 36 across one side of the substrate 33 adjacent the facing table 32.
The angle of the chamfer 36 is such that when the cutter is mounted in the appropriate orientation in the gauge section of the drill bit, the chamfer 36 is substantially tangential to the surrounding formation in the wall of the borehole so that the chamfer portion provides an increased area to absorb lateral impact loads due to engagement ofthe cutter with the formation. Although the chamfer 36 is shown as flat, it might also be slightly curved to the overall radius of the drill bit, as it extends away from the straight edge, so as to be concentric with the surrounding formation.
In accordance with the present invention the junction 37 between one end of the straight cutting edge 35 and the remainder of the peripheral surface 38 of the cutter is chamfered, in the form of a part-circular arc, to provide a gradual transition between the end of the cutting edge and the peripheral surface so as to reduce stress concentrations in this region. In the case where the cutter has an overall radius R of 6.7mm, the radius of curvature ofthe chamfer 37 may be 3.8mm. In this case, where only one junction is chamfered, the chamfer junction 37 is disposed lowermost when the bit is drilling downwardly.
In any ofthe arrangements according to the invention, a buffer or transition layer may be provided between the superhard facing table and the substrate. For example, the transition layer may comprise a material the critical properties of which are intermediate the properties of the materials of the facing table and the substrate. Alternatively or additionally, the interface between the facing table and the substrate, the interface between the facing table and the transition layer, and/or the interface between the transition layer and the substrate, may be configured and non-planar to enhance the bonding between the layers.
Claims (18)
1. A preform cutting element for a rotary drag-type drill bit including a facing table of superhard material having a front face, a peripheral surface, and a rear surface bonded to a substrate of a material which is less hard than the superhard material, the peripheral surface of the cutting element including a substantially straight cutting edge having at opposite ends thereofjunctions with the remainder of said peripheral surface, at least one of said junctions being formed with a chamfer which provides a transition between the end of the cutting edge and the adjacent portion of the remainder of the peripheral surface of the cutting element.
2. A cutting element according to Claim 1, wherein both said junctions are chamfered.
3. A cutting element according to Claim 1 or Claim 2, wherein the chamfer is smoothly curved to provide a continuous transition between the end of the cutting edge and the adjacent portion of the remainder of the peripheral surface.
4. A cutting element according to Claim 3, wherein the chamfer is in the form of a part-circular arc, opposite ends of which are substantially tangential to the cutting edge and the remainder of the peripheral surface respectively.
5. A cutting element according to Claim 2 and Claim 4, wherein the two partcircular arcs are of substantially the same radius.
6. A cutting element according to any of the preceding claims, wherein the remainder of the peripheral surface of the cutting element is part-circular.
7. A cutting element according to Claim 6, wherein said part-circular portion of the peripheral surface has an angular extent which is greater than 180 .
8. A cutting element according to Claim 7, wherein the angular extent of the partcircular portion of the peripheral surface is in the range of210"-270".
9. A cutting element according to any of the preceding claims, wherein the chamfer is in the form of a part-circular arc, and the remainder of the peripheral surface of the cutting element is part circular, the ratio of the radius of curvature of the chamfer to the radius of curvature of the peripheral surface being in the range of 1:1.4 to 1:1.8.
10 A cutting element according to Claim 9, wherein the radius of curvature of the peripheral surface is about 6.5mm and the radius of curvature of the chamfer is about 4mm.
11. A cutting element according to Claim 8, wherein the radius of curvature of the peripheral surface is about 9.5mm and the radius of curvature of the chamfer is about 6.5mm.
12. A cutting element according to any ofthe preceding claims, wherein the straight cutting edge is formed at the junction between the facing table and a flat on the substrate which extends substantially at right angles to the facing table and across the entire thickness of the substrate.
13. A cutting element according to any of Claims 1 to 11, wherein the straight cutting edge is formed at the junction between the facing table and an inclined surface on the substrate which extends at an angle from the cutting edge to the peripheral surface of the substrate.
14. A cutting element according to any of the preceding claims wherein at least part of the peripheral edge of the facing table is bevelled.
15. A cutting element according to any ofthe preceding claims wherein the interface between the facing table and the substrate is configured and non-planar.
16. A cutting element according to any ofthe preceding Claims 1 to 14, wherein a transition layer is provided between the facing table and the substrate having at least one property which is intermediate the corresponding property of the facing table and substrate.
17. A cutting element according to Claim 16, wherein the interface between the transition layer and the facing table and/or the substrate is configured and non-planar.
18. A cutting element for a rotary drag-type drill bit substantially as hereinbefore described with reference to Figures 5 and 6 or Figures 7 and 8 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9608172A GB2300437B (en) | 1995-05-02 | 1996-04-19 | Improvements in or relating to cutting elements for rotary drill bits |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GBGB9508892.8A GB9508892D0 (en) | 1995-05-02 | 1995-05-02 | Improvements in or relating to cutting elements for rotary drill bits |
| GB9608172A GB2300437B (en) | 1995-05-02 | 1996-04-19 | Improvements in or relating to cutting elements for rotary drill bits |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9608172D0 GB9608172D0 (en) | 1996-06-26 |
| GB2300437A true GB2300437A (en) | 1996-11-06 |
| GB2300437B GB2300437B (en) | 1998-07-22 |
Family
ID=26306962
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9608172A Expired - Fee Related GB2300437B (en) | 1995-05-02 | 1996-04-19 | Improvements in or relating to cutting elements for rotary drill bits |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2300437B (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2353550A (en) * | 1996-09-25 | 2001-02-28 | Smith International | Drill bit cutting element |
| US6564886B1 (en) | 1996-09-25 | 2003-05-20 | Smith International, Inc. | Drill bit with rows of cutters mounted to present a serrated cutting edge |
| GB2413575A (en) * | 2004-04-30 | 2005-11-02 | Smith International | Cutter having working surface with an edge chamfer of varying geometry |
| US7726420B2 (en) | 2004-04-30 | 2010-06-01 | Smith International, Inc. | Cutter having shaped working surface with varying edge chamfer |
| USD924949S1 (en) | 2019-01-11 | 2021-07-13 | Us Synthetic Corporation | Cutting tool |
| US20220389768A1 (en) * | 2021-06-07 | 2022-12-08 | Baker Hughes Oilfield Operations Llc | Cutting elements for earth-boring tools and related earth-boring tools and methods |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USD1026979S1 (en) | 2020-12-03 | 2024-05-14 | Us Synthetic Corporation | Cutting tool |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2294069A (en) * | 1994-10-15 | 1996-04-17 | Camco Drilling Group Ltd | Rotary drill bits |
-
1996
- 1996-04-19 GB GB9608172A patent/GB2300437B/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2294069A (en) * | 1994-10-15 | 1996-04-17 | Camco Drilling Group Ltd | Rotary drill bits |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2353550A (en) * | 1996-09-25 | 2001-02-28 | Smith International | Drill bit cutting element |
| GB2353550B (en) * | 1996-09-25 | 2001-04-11 | Smith International | Cutting element |
| US6564886B1 (en) | 1996-09-25 | 2003-05-20 | Smith International, Inc. | Drill bit with rows of cutters mounted to present a serrated cutting edge |
| GB2413575A (en) * | 2004-04-30 | 2005-11-02 | Smith International | Cutter having working surface with an edge chamfer of varying geometry |
| GB2413575B (en) * | 2004-04-30 | 2006-07-26 | Smith International | Cutter having shaped working surface with varying edge chamfer |
| US7726420B2 (en) | 2004-04-30 | 2010-06-01 | Smith International, Inc. | Cutter having shaped working surface with varying edge chamfer |
| US8037951B2 (en) | 2004-04-30 | 2011-10-18 | Smith International, Inc. | Cutter having shaped working surface with varying edge chamfer |
| USD924949S1 (en) | 2019-01-11 | 2021-07-13 | Us Synthetic Corporation | Cutting tool |
| USD947910S1 (en) | 2019-01-11 | 2022-04-05 | Us Synthetic Corporation | Drill bit |
| USD1026982S1 (en) | 2019-01-11 | 2024-05-14 | Us Synthetic Corporation | Cutting tool |
| US20220389768A1 (en) * | 2021-06-07 | 2022-12-08 | Baker Hughes Oilfield Operations Llc | Cutting elements for earth-boring tools and related earth-boring tools and methods |
| US11828109B2 (en) * | 2021-06-07 | 2023-11-28 | Baker Hughes Oilfield Operations Llc | Cutting elements for earth-boring tools and related earth-boring tools and methods |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9608172D0 (en) | 1996-06-26 |
| GB2300437B (en) | 1998-07-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20000419 |