BOTTOM COLLAR FOR ROLLER-BIT DRILLING Russian patent published in 1995 - IPC

FIELD: mining industry. SUBSTANCE: bottom collar for roller bit drilling has body 1, upper adapter 2, lower adapter 3, shock absorber including rod 4 with central passage 5, set of flexible members 7 precompressed by nut 6, spline pair 8 for torque transmission. Rod 4 has cuttings-protective valve 9 and roller bit 10 with oil deflecting bushing 11. Upper part of central passage 5 of rod 4 movably connected with central air pipe 12, sleeve 13 and cover 14 forming space 15 for lubricant, and they form from outside together with body 1, moisture separator 16 and upper adapter 2 - channel communicating through radial holes 18 of body 1 with casing string-borehole annulus. Installed in upper adapter 2 is filter-valve 19. Running from vessel 15 is branch pipe 20 with lubricant metering device 21. Rod 4 has radial holes 22 communicated with spaces of flexible members 7 and spline pair 8. Outer surface of lower adapter 3 has longitudinal ribs 23 reinforced with hard alloy or wear-resistant facing. EFFECT: higher strength of tool and intensified roller-bit drilling. 1 dwg