GB1402082A - Down-the hole hydropercussive device for use in drilling wells - Google Patents

Abstract

1402082 Boring earth &c SPETSIALNOE KONSTRUKTORSKOE BJURO GIDROIMPULSNOI TEKHNIKI SIBIRSKOGO OTDELENIA AKADEMII NAUK SSR 9 March 1973 [10 March 1972] 11505/73 Heading E1F A down-the-hole hydro-percussive drilling tool comprises a housing 1 slidably mounted on a hollow rod 3 and having a percussive mass 2 rigidly secured thereto, the interior 4 of the rod being in communication with an acceleration cavity 6 in the mass 2 and connectable to a source 5 of highly-pressurized liquid, a piston 9 being movable between two fixed stops 7, 8 on the rod and dividing the interior of the housing into two compartments 10, 11, the piston having ports 15 therein for providing communication between the two compartments. For cocking of the tool, the piston 9 is in its lowermost position and the ports 15 therein are closed by the stops. Pressurized liquid from a hydroaccumulator 5 enters compartment 11 via the hollow rod 3 and ports 14 therein, and forces housing 1 and mass 2 upwardly until a thrust pipe 16 therein urges the piston against the upper stop 7, the piston being held in this position by liquid entering a cavity 12 in the piston via ports 13. In this position pressure in the compartments is equalized by the piston ports 15 and the housing and mass are accelerated downwardly under the effect of liquid pressure in the cavity 6, and gravity. Following percussion a liner 18 falls downwardly abutting the piston to force it to its lowermost position once more. The drill string may be employed as the hydroaccumulator.