Abstract: An arrangement in a rock drill comprising a shank and a percussion piston and lifting sleeve for moving the shank towards percussion piston, and a method of controlling rock drilling. The arrangement comprises a lifting sleeve around the shank and a plurality of cylindrical lifting pistons around the shank. In the method, upon downward drilling, the magnitude of the feed force of the rock drill is decreased as the number of extension rods increases, and a force is set to act on some lifting pistons to move the shank towards the percussion point.

Abstract: A method for adjusting percussion pressure and a drilling machine. In the method the percussion power of a drilling machine is adjusted by moving a shank in the longitudinal direction of the drilling machine forwards when a smaller percussion power is to be transferred from the percussion piston to the shank. The drilling machine comprises at least two groups of pistons moving in the axial direction of the drilling machine, the pistons being connected to act on the shank by means of a pressure medium acting behind the pistons towards the front end of the drilling machine. The drilling machine comprises at least two separate groups of pistons whose travel with respect to one another is different and where pressure medium channels separate from one another lead to the cylinder spaces of both piston groups.

Abstract: During the drilling of rock by a rock drill bit, percussive impacts are applied to the drill bit by a reciprocating piston which impacts a shank that transmits the impacts to the drill bit. Secondary pistons are provided to push the shank forwardly in response to a pressure medium acting on rear surfaces of the secondary pistons. The secondary pistons push the shank to its optimum point of impact. During a drilling operation, as the piston applies percussive impacts, return pulses are reflected back to the secondary pistons. Pressure sensors detect the return pulses in the form of pressure pulses, which indicate whether the drill bit has encountered weaker or stronger materials. Based upon characteristics of the detected pressure pulses, the operation of the drilling machine, e.g., the feed and/or impact power thereof, is regulated, so that the shank is returned to its optimum point of contact.

Abstract: The invention relates to an arrangement for the axial bearing of the drilling machine. The drilling machine thereby comprises a body (6), a percussion device (1) fitted in the body, and a rotation bushing (3) functioning as a rotating means of a shank (2) positioned on an axial extension of the percussion device. Furthermore, an axial bearing is fitted within the body (6) for receiving the axial forces exerted on the body (6) through the shank (2). In order to provide resilience, the axial bearing is arranged to be displaceable in the axial direction under the influence of a pressure medium acting thereon. To resiliently receive a percussion impulse reflected from the rock during the drilling process, the pressure and volume flow of the pressure medium of the axial bearing is adjustable so that the position (Y) of the axial bearing is between the extreme positions (0,.DELTA.X) of the axial bearing under the normal operating conditions of the drilling machine.

Abstract: A method for optimizing percussive drilling, especially rock drilling, in which method the operation of the drilling device is adjusted for a desired drilling result to be obtained. According to the invention, a stress wave created in a drill rod as a result of a stroke is measured and the drilling device is adjusted on the basis of the measured stress wave. The adjusting is carried out e.g. by means of the damping rate or the spectrum of the measured stress wave or the shape of the stress wave and/or the energy fed by the different portions thereof.