Abstract: The invention relates to an axial bearing and to a rock drilling machine pro-vided with an axial bearing. The axial bearing (100) comprises a first piston (20) and a second piston (21). Axial contact surfaces (60, 43a) between the pistons (20, 21) are arranged in the same pressure space (28). The same pressure fluid fed to the axial bearing acts on the contact surfaces and on working pressure surfaces of the pistons.

Abstract: A method of generating a stress pulse, and an impact device. In the method, pressure fluid is fed as pressure pulses to a working chamber residing between the frame of the impact device and a tool such that the resulting force presses the tool towards the material to be processed. The impact device comprises a working chamber and means for conveying pressure fluid as pressure pulses thereto such that a force is produced between the frame of the impact device and a tool to press the tool towards the material to be processed.

Abstract: A pressure fluid operated impact device comprising a frame (2) whereto a tool (3) is mountable movably in its longitudinal direction, and control means (7) for controlling pressure fluid feed to the impact device (1), as well as a method of generating a stress pulse in a pressure fluid operated impact device. The impact device (1) comprises a working chamber (8) and a transmission piston (9) moving therein. Energy charging means for charging energy of pressure fluid and the control means are coupled to allow periodically alternately pressure fluid to flow to the working chamber (8) and, correspondingly, to discharge pressure fluid from the working chamber (8). In the method, pressure fluid is fed to the working chamber (8), which produces a force pushing the transmission piston (9) in the direction of the tool (3), thus generating a stress pulse in the tool (3).

Abstract: A rock drill includes a string of components interconnected by screw threads and connected to a shank. A percussion piston is reciprocated against the shank during a drilling operation, while a support device applies axial support to the rear of the shank, to enhance the drilling action. When the components are being unscrewed, the percussion piston is actuated to strike the rear end of the drill string, after the support device has at least partially released the axial support of the shank, to enable tensile stress to be generated in the components by the percussive impacts to facilitate unscrewing of the components.

Abstract: A rock drill includes a shank. A percussion piston is arranged to hit the back end of the shank. Further, a pulling element is arranged around the shank, to which a pulling force can be directed in such a manner that the shank can, by the pulling force, be moved toward the percussion piston, when stuck drilling equipment is freed. During rock drilling, a push force is arranged to act on the pulling element, the push force being opposite with respect to the pulling force. The push force is designed in such a manner that during drilling the pulling element moves due to the push force toward the front section of the drill to be at a predefined distance from the position corresponding to the impact point of the shank.

Abstract: A rock drill that comprises a shank (6), the back end of which a percussion piston (10) is arranged to hit. Further, a pulling element (17, 29) is arranged around the shank, to which a pulling force can be directed in such a manner that the shank (6) can by means of said pulling force be moved toward the percussion piston (10), when stuck drilling equipment is freed. During rock drilling, a push force is arranged to act on the pulling element (17, 29), the push force being opposite with respect to the pulling force. The push force is designed in such a manner that during drilling the pulling element (17, 29) moves due to said push force toward the front section of the drill to be at a predefined distance from the position corresponding to the impact point of the shank.

Abstract: The invention relates to a method of opening joints of drilling components attached to a rock drill, and to a rock drill which enabling this. According to the idea of the invention, in striking compression stress, which proceeds towards a drill bit (10), is generated in the drilling equipment (5) by striking with a percussion piston. When the drilling components are struck off, the axial bearing included in the drilling machine does not substantially support the drilling equipment, but the compression stress generated by striking is reflected from the drill bit (10) as stress of the opposite sign and generates the desired tensile stress in the drilling equipment. After striking the threaded joints of the drilling components can be opened easier by rotating the rotating device in the opposite direction.

Abstract: The invention concerns an arrangement for controlling a hydraulic rock drilling device. The arrangement includes a pressure ratio valve that is used for adjusting the relation between the pressures in the pressure channel leading to the percussion device and/or another actuator, such as a shank stabilizer, and the pressure channel leading to the feed mechanism. The pressure ratio valve is arranged to keep the relation between the pressures of the actuator and the feed mechanism constant over the normal drilling range.

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 an axial bearing in a drilling machine. The drilling machine includes a frame (6), a percussion device (1) fitted in the frame, and a shank (2) positioned on an axial extension of the percussion device. The frame (6) further includes an axial bearing formed by a number of pistons (4a, 4b) to receive axial forces acting on the frame (6) through the shank (2). The length of travel of some pistons (4b) towards the forward portion of the drilling machine is limited so that when they are in their forward position and the shank (2) is supported by the pistons (4a, 4b), the shank (2) is substantially at its optimal percussion point.

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 coupling arrangement for a percussion drilling machine for coupling of a shank (7) unrotatably to a frame bushing (2) rotatably mounted in a frame and rotated by a rotating device. The frame bushing is provided with axial driving grooves (12) opening towards the shank and the shank is provided with axial counter grooves (13) opening towards the frame bushing. Rod-like wedge pieces (11) are mounted each in a pair of grooves formed by the grooves. The cross-section of each wedge piece comprises an arched surface portion (11a) and at least one planar surface portion (11b). Such wedge piece can adjust its position by turning in one groove of the pair of grooves so that the planar surface of the wedge piece is pressed into a planar contact with the planar surface of the other groove.