SUBMERSIBLE DRILLING TOOL Russian patent published in 1994 - IPC

FIELD: drilling. SUBSTANCE: drilling tool has block of working cylinders 1, striking pistons 2 and 3, ring valve 4, eccentric 5, seat 6 and valve box 7. Seat 6 and eccentric 5 are fixed with pins 8 and 9. Drill bits 13 and 14 are mounted in frontal part of working block of cylinders fixed with key 15. Striking pistons 2 and 3 with increased and decreased working areas by specific mass and energy of impact are balanced. Such drilling tool provides for effective cleaning of face and removal of slime to entrance of borehole. Design makes it possible to develop a number of versions of drilling tools intended for drilling of boreholes having diameter 220-500 mm. Effective distraction of whole area of face is achieved thanks to increased diameter of at least one of working cylinders with striking piston face part of drill bit overlaps distance from outer contour to axis of drilling tool. EFFECT: simplified design, improved efficiency. 2 dwg