Abstract

A fluid pressure hitting device comprises a piston inserted in a cylinder, a chisel, and a first, second, and third chambers. The chisel is fitted in the cylinder such that a part of the chisel projects from one axial end of the cylinder and is configured to further project from that axial end due to being hit by the piston as the piston slides toward the one axial end. The first through third chambers are partitioned by an inner peripheral surface of the cylinder and an outer peripheral surface of the piston. The first through third chambers are arranged in the axial direction in order fluid the one axial end to another axial end of the cylinder. A flow path is configured to supply fluid from a fluid supply portion when the piston hits the chisel, to the first chamber.

IPC Classes  ?

• B25D 17/02 - Percussive tool bits
• B25D 9/18 - Valve arrangements therefor involving a piston-type slide valve
• B25D 9/14 - Control devices for the reciprocating piston

Abstract

A fluid pressure striking device (1): has a tubular cylinder (2), a piston (3) that is fit inside the cylinder (2) and that can slide in the axial direction of the cylinder (2), and a rod-shaped chisel (4) that is inserted so that a portion thereof projects from one end of the cylinder (2) in the axial direction and that projects further from the one end of the cylinder (2) by being struck by the piston (3) sliding inside the cylinder (2) in the axial direction to the one end; has a first chamber (5), a second chamber (6), and a third chamber (7) partitioned from the one end side in the axial direction to the other end side in the axial direction of the cylinder (2) by the inner circumferential wall (2a) of the cylinder (2) and the outer circumferential wall (3s) of the piston (3); and has, formed therein, a channel capable of supplying a fluid to the first chamber (5) from a fluid supply unit, which has a higher fluid pressure than the first chamber (5) when the piston (3) strikes the chisel (4).

IPC Classes  ?

• B25D 9/14 - Control devices for the reciprocating piston

Abstract

In this fluid pressure hammering device, which automatically switches/controls the stroke of a piston in accordance with the rock quality of a rock to be pulverized, control accuracy is increased. A strike-switching pilot hole (40) for removing high-pressure oil during hammering is provided to a reversal chamber (5). By means of a fluid ejection valve (41) that operates by incurring the hydraulic pressure from the stroke-switching pilot hole (40), oil is successively collected in a fluid chamber (32) provided to a stroke switching valve (30), and when the amount of oil in the fluid chamber (32) exceeds a baseline amount, short strokes are switched to long strokes by means of the switching of the stroke switching valve (30).

IPC Classes  ?

• B25D 9/26 - Control devices for adjusting the stroke of the piston or the force or frequency of impact thereof
• E21B 1/26 - Percussion drilling with a reciprocating impulse member the impulse member being a piston driven directly by fluid pressure by liquid pressure