SECTIONAL DRILL BIT Russian patent published in 1995 - IPC

FIELD: mining industry. SUBSTANCE: sectional drill bit has nut 9 positioned inside body 1. Nut 9 interacts with body 1 and bushing 8 by means of threads 11 of different pitches. Threads 11 are located on outer surface of nut 9 and annular recess 19 is made between threads 11. Recess 19 is communicated with annular bore 16 with the aid of inclined holes 18. Cylindrical surface 17 is made under tapered surface 14. Bore 16 is located below recess 19. Coaxial radial holes 20 and 21 are made in bushing 8, shanks 4 and body 1. Holes 21 are closed with screws 25. Lugs 6 has longitudinal holes 22 communicating overrunning surface of lug 6 with hollow of radial hole 21. Inclined grooves 23 and screw grooves 24 may be made on overrunning surfaces of lugs 6 and on body surface, respectively. Grooves 23 and 24 are conjugated to each other. Holes 22 are opened to inclined grooves 23. Section of shank 4 adjacent to bushing 8 is made in form of wedge protrusion 7 to rock breaking tool. Outer surface of bushing 8 has groove mating protrusion 7. EFFECT: higher efficiency. 3 cl, 4 dwg