Abstract: A hydraulic hammering device enables an auto-stroke mode and an idle strike prevention mode to coexist with a simple circuit configuration. A first control valve controls advancing and retracting movements of a piston and a second control valve select either the auto-stroke mode and the idle strike prevention mode. To the second control valve, a shared spool is slidably fitted and a mode selection means is disposed. When the mode selection means allows supply of pressurized oil to an auto-stroke setting portion of the shared spool and prohibits discharge of pressurized oil from an idle strike prevention setting portion, the auto-stroke mode is selected. When prohibiting supply of pressurized oil to the auto-stroke setting portion and allowing discharge of pressurized oil from the idle strike prevention setting portion, the idle strike prevention mode is selected.

Abstract: A hydraulic hammering device includes a piston front chamber and a piston rear chamber defined between an outer circumferential surface of the piston and an inner circumferential surface of the cylinder and disposed separately from each other at front and rear, respectively, in an axial direction. A switching-valve mechanism drives the piston by switching at least one of the piston front chamber and the piston rear chamber into communication with at least one of a high pressure circuit and a low pressure circuit. An acceleration piston is disposed behind the piston and is configured to come into contact with the piston during a retreat stroke thereof to urge the piston forward, in which a timing where the acceleration piston itself starts to come in contact with the piston is set to be earlier than a timing where the piston is braked by the switching-valve mechanism.

Abstract: Provided is a hydraulic striking device in which a reverse operation circuit and a forward operation circuit can switch connection states to a high pressure circuit and a low pressure circuit by means of an operation switching valve. Further, the hydraulic striking device is configured to be selectable between a reverse operation mode or a forward operation mode by operating the operation switching valve. A high/low pressure switching portion is provided with a shortening portion for reducing the time required for high/low pressure switching operation in piston front and rear chambers in association with retraction of a valve to be shorter than the time required for high/low pressure switching operation in the piston front and rear chambers in association with advancement of the valve.

Abstract: Provided is a two-piston hydraulic striking device that has stable operativity. This two-piston hydraulic striking device includes two striking mechanisms for striking one transfer member. Each striking mechanism has a pressure receiving area ratio between the front and rear of a piston thereof set in such a way that the two striking mechanisms have the same cycle time.

Abstract: Hammering power of a hydraulic hammering device is improved by shortening a piston stroke, while keeping hammering energy. The device includes a cylinder, a piston slidingly fitted in the cylinder, and a piston front chamber and a piston rear chamber defined between an outer circumferential surface of the piston and an inner circumferential surface of the cylinder and disposed separately from each other at front and rear, respectively, in an axial direction. The device also includes a switching-valve mechanism driving the piston by switching at least one of the piston front or rear chamber into communication with at least one of a high pressure circuit or a low pressure circuit, and an acceleration piston disposed behind the piston and coming in contact with the piston during a retreat stroke of the piston to urge the piston forward in cooperation with braking force by pressurized oil acting on the piston.

Abstract: A hydraulic hammering device is capable of sufficiently transmitting blow energy to bedrock while further strengthening cushioning action and suppressing damage to equipment. The device includes a pushing piston disposed behind a transmission member and having a smaller propulsive force than that of a main body, a damping piston positioned behind the pushing piston to slide reciprocally forwards and backwards and having a greater propulsive force than that of the main body, a direction-restrictor in a high-pressure circuit between pushing and damping chambers, to which hydraulic fluid is supplied for providing the pistons with propulsive forces, and a fluid supply source. The direction-restrictor restricts an outflow from the chambers side to the fluid supply source side while allowing fluid inflow from the fluid supply source side to the chambers and the pushing chamber sides. A throttle in a drain circuit discharges leaked fluid from a sliding contact location to a tank.

Abstract: Provided is a two-piston hydraulic striking device that has stable operatively. This two-piston hydraulic striking device includes two striking mechanisms for striking one transfer member. Each striking mechanism has a pressure receiving area ratio between the front and rear of a piston thereof set in such a way that the two striking mechanisms have the same cycle time.

Abstract: A hydraulic hammering device that uses a scheme in which a front chamber is switched into communication with a low-pressure circuit when a piston advances, wherein occurrences of “galling” to the piston at a sliding contact portion with a front-chamber liner is reduced. The front chamber has the front-chamber liner fitted to an inner surface of a cylinder. A hydraulic chamber space communicating with the front chamber and filled with hydraulic oil is formed as a cushion chamber on the inner peripheral surface of a rear portion of the front-chamber liner. The cushion chamber has a second drain circuit (from first end face grooves to slits to second end face grooves), which is provided separately from a drain circuit that guides the hydraulic fluid passing through a liner bearing of the front-chamber liner to the low-pressure circuit.

Abstract: A hydraulic hammering device is capable of sufficiently transmitting blow energy to bedrock while further strengthening cushioning action and suppressing damage to equipment. The device includes a pushing piston disposed behind a transmission member and having a smaller propulsive force than that of a main body, a damping piston positioned behind the pushing piston to slide reciprocally forwards and backwards and having a greater propulsive force than that of the main body, a direction-restrictor in a high-pressure circuit between pushing and damping chambers, to which hydraulic fluid is supplied for providing the pistons with propulsive forces, and a fluid supply source. The direction-restrictor restricts an outflow from the chambers side to the fluid supply source side while allowing fluid inflow from the fluid supply source side to the chambers and the pushing chamber sides. A throttle in a drain circuit discharges leaked fluid from a sliding contact location to a tank.

Abstract: Provided is a hydraulic hammering device having improved hammering efficiency and of low cost. A piston has a valve switching groove between large-diameter sections thereof. A cylinder has three control ports at positions corresponding to the valve switching groove. A switching valve mechanism has a valve presser for always pressing a valve in one direction and also has a valve controller for moving, when supplying pressurized oil, the valve in the opposite direction against the pressing force of the valve presser. A valve control port communicates with the valve controller so as to supply the pressurized oil to the valve controller and is separated from a piston front chamber and a piston rear chamber. Only either a piston retraction control port or a piston advance control port communicates with the valve control port depending on advance or retraction of the valve switching groove.

Abstract: A drilling device with improved fuel efficiency, reduced impact on the environment, and the like is provided. Specifically, a drilling device performs unload control of a compressor when an engine starts up, and brings the air pressure in an air tank to a first air pressure. Moreover, the air pressure in the air tank is kept at the first air pressure while the engine is driven and a flushing mechanism is not driven. In addition, unload control of the compressor is performed when the flushing mechanism starts up, and the air pressure in the air tank is increased to a second air pressure that is higher than the first air pressure. For example, the first air pressure and the second air pressure are a low pressure (0.5 MPa) and a high pressure (1.03 MPa), respectively.

Abstract: Hammering power of a hydraulic hammering device is improved by shortening a piston stroke, while keeping hammering energy. The device includes a cylinder, a piston slidingly fitted in the cylinder, and a piston front chamber and a piston rear chamber defined between an outer circumferential surface of the piston and an inner circumferential surface of the cylinder and disposed separately from each other at front and rear, respectively, in an axial direction. The device also includes a switching-valve mechanism driving the piston by switching at least one of the piston front or rear chamber into communication with at least one of a high pressure circuit or a low pressure circuit, and an acceleration piston disposed behind the piston and coming in contact with the piston during a retreat stroke of the piston to urge the piston forward in cooperation with braking force by pressurized oil acting on the piston.

Abstract: A drilling device is brought into an idling state by maintaining the engine speed at a first speed while waiting for a drilling operation. The engine speed is increased to a second speed that is higher than the first speed when any one of a rotation operation, a feeding operation, a rod exchange operation, or a boom operation is performed for a rock drill. The engine speed is increased to a third speed that is higher than the second speed when a striking operation or a flushing operation is performed, and the engine speed is decreased from the third speed to the first speed after the striking operation and the flushing operation finish. For example, the first speed is a low speed, the second speed is a medium speed, and the third speed is a high speed.

Abstract: A drilling device with improved fuel efficiency, reduced impact on the environment, and the like is provided. Specifically, a drilling device performs unload control of a compressor when an engine starts up, and brings the air pressure in an air tank to a first air pressure. Moreover, the air pressure in the air tank is kept at the first air pressure while the engine is driven and a flushing mechanism is not driven. In addition, unload control of the compressor is performed when the flushing mechanism starts up, and the air pressure in the air tank is increased to a second air pressure that is higher than the first air pressure. For example, the first air pressure and the second air pressure are a low pressure (0.5 MPa) and a high pressure (1.03 MPa), respectively.

Abstract: A drill rod has a fitting portion protruding toward the distal end of the drill rod. The drill rod fitting portion further encompasses a parallel male thread portion in which a minimum distance from a first axial line in a cross-section perpendicular to the first axial line is constant; and a male thread ending portion is continuous with a proximal end of the parallel male thread portion. The minimum distance of the ending portion increases as a proximal end is approached. Furthermore, the fitting portion is formed such that the minimum distance does not decrease as the proximal end is approached from a distal end thereof. Additionally, the proximal end of the male thread ending portion is positioned where a distance from the first axial line gradually increases as the proximal end of the male thread ending portion is approached from the parallel male thread.

Abstract: A drill rod having a fitting portion protruding toward the distal end and of the drill rod and extending along a first axial line, wherein the fitting portion includes: a parallel male thread portion in which a minimum distance from the first axial line in a cross-section perpendicular to the first axial line is constant; and a male thread ending portion which is continuous with a proximal end of the parallel male thread portion, and in which the minimum distance increases as approaching toward a proximal end thereof; wherein the fitting portion is formed such that the minimum distance does not decrease as approaching from a distal end to a proximal end thereof; and the proximal end of the male thread ending portion is positioned on a face where a distance from the first axial line gradually increases as approaching from the parallel male thread to the proximal end of the male thread ending portion.