US 12,312,866 B2
Drill assembly for percussive drilling, a drill bit and a drill string element
Mika Koskinen, Tampere (FI); and Kimmo Ala-Kanto, Tampere (FI)
Assigned to ROBIT PLC, Lempäälä (FI)
Appl. No. 18/004,481
Filed by ROBIT PLC, Lempäälä (FI)
PCT Filed Jul. 8, 2020, PCT No. PCT/FI2020/050486
§ 371(c)(1), (2) Date Jan. 6, 2023,
PCT Pub. No. WO2022/008786, PCT Pub. Date Jan. 13, 2022.
Prior Publication US 2024/0263525 A1, Aug. 8, 2024
Int. Cl. E21B 10/36 (2006.01); E21B 6/00 (2006.01); E21B 17/042 (2006.01)
CPC E21B 10/36 (2013.01) [E21B 6/00 (2013.01); E21B 17/0426 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A drill assembly for percussive drilling, the drilling assembly comprising:
a drill bit extending along a longitudinal direction and having:
a downhole portion having a downhole end surface equipped with inserts configured for transferring percussive impacts to points of contact with a borehole, and
an attachment portion extending from the downhole portion towards an uphole direction, the attachment portion having a cylindrical male coupling thread; and
a cylindrical hollow drill string element configured for transferring at least percussive impacts from a percussion device to the drill bit, the drill string element extending along the longitudinal direction and having, on a downhole-side end thereof, a female coupling thread for threadedly coupling with the male coupling thread;
wherein the drill bit includes a first annular impact surface arranged on an uphole-side end the downhole portion, the first annular impact surface surrounding the attachment portion;
wherein the drill string element includes, at a downhole-side end thereof, a second annular impact surface;
wherein the drill bit is configured to be threadedly coupled with the drill string element such that the first annular impact surface abuts the second annular impact surface so as to transfer percussive impact during operation from the drill string element to the drill bit through the first and second impact surfaces; and
wherein the first annular impact surface, and respectively, the second annular impact surface are inclined with respect to a plane perpendicular to the longitudinal direction.