Durable rock bit for blast hole drilling

Patent metadata

Field	Value
Publication number	US-10364610-B2
Application number	US-201715670118-A
Country	US
Kind code	B2
Filing date	Aug 7, 2017
Priority date	Aug 9, 2016
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

A rock bit for blast hole drilling includes: a bit body having a coupling formed at an upper end thereof, a plurality of lower legs, a dome formed between the legs, and a bore formed through the coupling and the dome; a plurality of skirts, each skirt covering a gap formed between adjacent legs and each skirt mounted to edges of adjacent legs; a plurality of roller cones, each rotary cone rotatably mounted to a respective bearing shaft of a respective leg; a row of gage cutters mounted to each roller cone; a row of inner cutters mounted to each roller cone; one or more nose cutters mounted to each roller cone; and a center jet secured in the bore. Each cutter is an insert.

First claim

The invention claimed is:

1. A rock bit for blast hole drilling, comprising:
a bit body having a coupling formed at an upper end thereof, a plurality of lower legs, a dome formed between the legs, and a bore formed through the coupling and the dome;
a plurality of skirts, each skirt covering a gap formed between adjacent legs and each skirt mounted to edges of adjacent legs;
a plurality of roller cones, each rotary cone rotatably mounted to a respective bearing shaft of a respective leg;
a row of gage cutters mounted to each roller cone;
a row of inner cutters mounted to each roller cone;
one or more nose cutters mounted to each roller cone; and
a center jet secured in the bore and comprising:
an orifice plate having a plurality of ports or a single port with a plurality of branches, each port or branch aimed at an interface between adjacent roller cones; and
a back flow valve operable to open in response to injection of drilling fluid down the bore and to close for blocking upward flow through the bore,

wherein:
each cutter is an insert, and
inner and outer surfaces of each skirt extend straight across the respective gap.

2. The bit of claim 1 , wherein:
the bit further comprises a plurality of sets of roller bearings, each set disposed between a respective cone and a respective bearing shaft, and
each leg has a passage extending from the bore to the respective set of bearings.

3. The bit of claim 2 , wherein:
the center jet comprises a tube having a plurality of sets of slots aligned with inlets of the passages, and
each set of slots is oriented to face a respective passage.

4. The bit of claim 1 , wherein the orifice plate has the plurality of ports.

5. The bit of claim 4 , wherein the orifice plate further has a center port aimed downward.

6. The bit of claim 4 , wherein the orifice plate further has a plenum formed therein.

7. The bit of claim 1 , wherein the orifice plate has the single port with a center portion aimed downward and the plurality of branch portions.

8. The bit of claim 1 , further comprising a set of interstitial protectors mounted on each roller cone.

9. The bit of claim 8 , wherein the interstitial protectors are located between adjacent nose cutters.

10. The bit of claim 1 , wherein at least a portion of each cone is treated to resist erosion.

11. The bit of claim 10 , wherein the treatment is case hardening.

12. The bit of claim 10 , wherein the treatment is hardfacing.

13. The bit of claim 10 , wherein the treated portion is located between the inner cutters and the nose cutters and at a mouth of each cone.

14. The bit of claim 1 , wherein the coupling is a threaded pin.

15. The bit of claim 1 , wherein the center jet is the only nozzle or port of the drill bit for discharging fluid to remove cuttings.

16. A rock bit for blast hole drilling, comprising:
a bit body having a coupling formed at an upper end thereof, a plurality of lower legs, a dome formed between the legs, and a bore formed through the coupling and the dome;
a plurality of skirts, each skirt covering a gap formed between adjacent legs and each skirt mounted to edges of adjacent legs;
a plurality of roller cones, each rotary cone rotatably mounted to a respective bearing shaft of a respective leg;
a row of gage cutters mounted to each roller cone;
a row of inner cutters mounted to each roller cone;
one or more nose cutters mounted to each roller cone; and
a center jet secured in the bore and comprising:
an orifice plate having a plurality of ports or a single port with a plurality of branches, each port or branch aimed at an interface between adjacent roller cones; and
a back flow valve operable to open in response to injection of drilling fluid down the bore and to close for blocking upward flow through the bore,

wherein:
each cutter is an insert, and
each skirt is arcuate and extends along a curved path across the respective gap, such that when the rock bit is viewed from a bottom thereof, a foot print of the skirts and gage lands of the cones resembles a circle.

Assignees

• Varel Int Ind Lp

Inventors

• Beavers Tony Jack
• Kongamnach Amnach

Classifications

• E21B10/22

  characterised by bearing, lubrication or sealing details · CPC title

• E21B10/18

  characterised by conduits or nozzles for drilling fluids · CPC title

• E21B10/16 Primary

  characterised by tooth form or arrangement · CPC title

• E21B10/08 Primary

  Roller bits (E21B10/26 takes precedence; roller core bits E21B10/06; characterised by wear resisting parts E21B10/50) · CPC title

• E21B10/61

  characterised by the nozzle structure · CPC title