Systems and methods for mounting a cutter in a drill bit
Rotary drill bits may include on or more cutting element assemblies which include a cutter and a mounting system. In one embodiment, the mounting system includes a housing, a first bearing component disposed within the housing, and a second bearing component associated with the cutting element. In certain embodiments, the bearing components may comprise a table of superhard material bonded with a substrate. In one or more embodiments, the bearing components may include bearing surfaces that are arcuate. For example, the bearing surfaces may be substantially spherical (a portion of a sphere). The bearing components may be arranged to act as a radial bearing as well as a thrust bearing for the cutting element, enabling the cutting element to rotate about a longitudinal axis of the cutter, relative to the housing, while also enabling the longitudinal axis of the cutter to be displaced (change angles) relative to the housing.
1. A cutting insert assembly comprising:
a cutting insert;
a housing having a side wall and a floor defining a pocket, the pocket being sized and configured to receive a portion of the cutting insert;
a spherical bearing, the spherical bearing and the cutting insert being cooperatively configured to enable the cutting insert to rotate about a rotational axis relative to the housing;
a retaining member having a portion extending through the floor of the housing and engaging the cutting element, the retaining member being configured to retain the cutting insert within the pocket; and
a spherical seat member disposed between a portion of the retaining member and the floor of the housing.
2. The cutting insert assembly of claim 1 , wherein the spherical bearing and the cutting insert are cooperatively configured to enable the rotational axis to vary angularly relative to the housing.
3. The cutting insert assembly of claim 1 , wherein the cutting insert and the housing are arranged such that a clearance gap is maintained between an external sidewall of the cutting insert and an internal sidewall of the housing while the cutting insert rotates relative to the housing.
4. The cutting insert assembly of claim 1 , further comprising at least one seal disposed between the housing and the cutting insert.
5. The cutting insert assembly of claim 4 , wherein the housing, the cutting insert and the at least one seal are arranged to maintain a pressure within the pocket within a defined range.
6. The cutting insert assembly of claim 1 , wherein the housing includes at least one passage for communication with a pressure compensating system.
7. The cutting insert assembly of claim 1 , wherein the cutting insert is substantially cylindrical and includes a plurality of grooves formed in a peripheral region of the cutting insert.
8. The cutting insert assembly of claim 7 , wherein the plurality of grooves are each at least partially formed in a side surface of the cutting insert.
9. The cutting insert assembly of claim 1 , wherein the spherical bearing comprises a table of superhard material bonded to a substrate, wherein a bearing surface is formed in the table of superhard material.
10. A rotary drill bit for drilling a subterranean formation, the drill bit comprising:
a bit body;
at least one cutting insert assembly coupled to the bit body and configured to rotate with the bit body about a first axis, the cutting insert assembly comprising:
a cutting insert;
a housing coupled with the bit body, the housing having a pocket formed therein, the pocket being sized and configured to receive a portion of the cutting insert;
a spherical bearing, the spherical bearing and the cutting insert being cooperatively configured to enable the cutting insert to rotate about a second axis relative to the housing;
wherein the spherical bearing and the cutting insert are cooperatively configured to enable the second axis to vary angularly relative to the housing.
11. The rotary drill bit of claim 10 , wherein the housing is brazed to the bit body.
12. The rotary drill bit of claim 10 , wherein the housing includes a first housing component brazed to the bit body and a second housing component threadably coupled to the first housing component.
13. The rotary drill bit of claim 10 , further comprising at least one seal disposed between the housing and the cutting insert, wherein the housing, the cutting insert and the at least one seal are arranged to maintain a pressure within the pocket within a defined range.
14. The rotary drill bit of claim 10 , further comprising a vibrational member coupled with the cutting insert and configured to induce vibration between the cutting insert and the housing when external cutting forces are applied to the cutting insert.
15. A method of drilling a subterranean formation, the method comprising:
providing a drill bit having a body, a cutting insert coupled with the body via a housing having a pocket formed therein, at least a portion of the cutting insert being disposed in the pocket;
providing a spherical bearing component between the cutting insert and the housing;
providing a seal between the housing and the cutting insert;
engaging a subterranean formation with the drill bit while rotating the drill bit about a first rotational axis;
rotating the cutting insert about a second rotational axis relative to the housing while rotating the drill bit about the first rotational axis;
angularly varying the second rotational axis relative to the housing.
16. The method according to claim 15 , further comprising maintaining a clearance gap located between the housing and the cutting insert that extends from the seal towards the at least one spherical bearing component while rotating the cutting insert about the second rotational axis.