The invention concerns a rock drill (2) for activating a rotatable and reciprocable drill steel assembly (FIG. 1 ). A reversible motor (50) is coupled to a striking bar (3) for rotating the drill steel. The striking bar is struck by a percussion piston (10). A rotary fluid valve (15) is operating the piston. A disconnectable coupling (37,38,43) in normal operation couples both the valve (15) and the striking bar (3) with the motor (50). In special modes the motor operates only the percussion piston, e.g. for retracting a drill rod, or only rotates the striking bar (3), e.g. for connecting and disconnecting drill rods.
A percussion drill 10 has a tubular fluid transmitting body 14, with a drill bit 16 mounted on a drill bit support 20 itself mounted in body 14 via a spring 22 and salines 24. A mass 28 is spring mounted in the body 14 and is movable to impact on a face 26 of the support 20. Mounted to the mass 28 is a rotating valve 32 comprising two valve plates 34, 36. Each plate 34, 36 defines a slot 38, 40, such that rotation of one of the valve plates 36 relative to the other moves the slots 38, 40 into and out of alignment; the change in alignment of the slots 38, 40 alters the flow of drilling fluid through the valve 32, so altering the drilling fluid pressure force acting on the mass 28, so causing mass 28 to push against the spring 30, and impact on the drill bit support 20 providing a percussive act ion at the drill bit 16.
A drilling apparatus 1 having a twin-impact system can work continuously with a shank end 5 is provided with a compensation ring 10 on the rotary impact side, which has a material with hardness that is lower than that of the material of the pipe and striker 8 and/or corresponding to the adjacent end portion 11 of the shank end 5 and has a shape and/or surfaces 21, 22 to compensate for the applied forces.
An impact device 1 that is continuously controllable in terms of impact rate and impact force contains a percussion piston 25 that can move back and forth in the inner boring of the cylinder 3, and that is controlled via a rotary valve 15 having as rotary engine 16. The rotary valve 15 and the rotary engine 16 are positioned separately from the percussion piston 25, either on or in the cylinder 3, and are linked only via portings 20, 22, 24 to the pump connection 21 and the tank connection 23, or to the double-sided piston areas A1, A2, so that the valve can be used with practically any type of impact device, without requiring substantial alteration of its structural dimensions. In addition, an advantageous continuous control of impact rate and impact force with a constant power output is ensured.
A rock drill includes a housing in which are disposed a reciprocable percussive device, slidably mounted in the housing, a rotary device, and a shank adapter aligned with the percussive device. The shank adapter includes first and second adapter portions. The first adapter portion has a front end and a rear end, the rear end arranged to be impacted by the percussive device and rotated by the rotary device. The second adapter portion has a rear end releasably connected to the front end of the first adapter portion, and a front end carrying a coupling adapted for connection with a drill rod component.
A hydraulic rock drill comprises a housing having a piston and valve bore formed therein, a rotation motor, and a fluid connection and fluid reservoir interposed between the housing and the rotation motor. Fluid connections to the hydraulic rock drill comprise a single inlet fluid connection to the housing and a single exhaust fluid connection from the rotation motor. The working shoulder areas of the piston are proportioned so that the exhaust stroke of the piston will pressurize the fluid in the reservoir, providing a fluid inlet source for the rotation motor. When the rotation torque demand increases, pressure in the fluid reservoir and pressure in the fluid inlet connection will rise accordingly, thus providing higher rotation torque while maintaining impact power. When fluid inlet pressure reaches a predetermined limit, rotation and impact will lessen or cease altogether.
