A tool coupling device for coupling a tool can comprise a drive shaft for coupling to the drive, an output shaft for coupling to the tool, the output shaft being rotatable about a central axis (A), a transmission unit connected between the drive shaft and the output shaft and translating a rotational movement of the drive shaft at an input speed (n.sub.S) into a rotational movement of the output shaft at an output speed (n.sub.W) greater than the input speed (n.sub.S) and a non-rotating housing, wherein the transmission unit, and at least a part of the input shaft and a part of the output shaft that are both coupled to the transmission unit, are arranged within the housing, wherein the drive shaft is rotatably mounted on the housing; and wherein the output shaft is rotatably supported solely on the input shaft and is not rotatably supported on the housing.

A tool holder of a machine tool, in which the machine tool includes a spindle head and a spindle supported by the spindle head, includes: a shank portion attached to the spindle; a rotary portion integrally provided to the shank portion and to which a welding tool (processing tool) used for friction stir welding is attachable; a bearing mechanism (bearing) supporting the rotary portion so that the rotary portion is rotatable; and a bearing holder holding the bearing mechanism, in which the bearing holder is disposed facing the spindle head and is capable of transmitting a load applied to the bearing mechanism to the spindle head.

A newly configured centerpoint drill and a drill attachment device that can be attached to a conventional cordless drill include configurations that require a user's hand to be in direct alignment with the keyless chuck of the drill to enable a user or operator to apply maximum pressure or force during use of a drill to reduce time and effort spent by a user/operator.

A tool spindle for machine tool includes a tool spindle having a front end in which a tool is mounted and installed to be rotatable, and a vibration damping device mounted in a rear end of the tool spindle to damp cutting vibration generated at the front end of the tool spindle, and including a rigid member coupled to the rear end of the tool spindle and a tuned mass member elastically supported by the rigid member.

A tool spindle for machine tool includes a tool spindle having a front end in which a tool is mounted and installed to be rotatable, and a vibration damping device mounted in a rear end of the tool spindle to damp cutting vibration generated at the front end of the tool spindle, and including a rigid member coupled to the rear end of the tool spindle and a tuned mass member elastically supported by the rigid member.

A power tool includes a motor including a rotor and multi-phase stator windings; a driver circuit having multiple switch elements for outputting switch signals to drive the motor to rotate; and a controller electrically connected to at least the driver circuit and the motor. The controller is configured to acquire rotor position information of the motor and adjust a resultant magnetic potential of the motor according to the rotor position information such that an output electrical parameter of the motor corresponding to the resultant magnetic potential is within a preset parameter range.

A power tool includes a motor including a rotor and multi-phase stator windings; a driver circuit having multiple switch elements for outputting switch signals to drive the motor to rotate; and a controller electrically connected to at least the driver circuit and the motor. The controller is configured to acquire rotor position information of the motor and adjust a resultant magnetic potential of the motor according to the rotor position information such that an output electrical parameter of the motor corresponding to the resultant magnetic potential is within a preset parameter range.

A vibration damping device for a machine tool spindle is provided. An annular support plate is mounted at a lower portion of a distal end of the spindle, a plurality of support bars is fixed to the support plate in a vertical direction and installed in a longitudinal direction of the spindle adjacent to an outer periphery of the spindle, a pair of weight disks stacked by a plurality of arc-shaped disks made of a tuned mass member is fixed to be in close contact with the outer periphery of the spindle, facing each other, and a damping sheet made of an elastic member is inserted between the outer periphery of the spindle and the weight disks. The vibration damping device of the present invention may maximize a vibration damping effect by installing the vibration damping device at a position closest to the spindle where a vibration occurs. Furthermore, the vibration damping device of the present invention may effectively attenuate a variety of vibration phenomena having various resonant frequencies of a machine tool spindle by constituting the vibration damping device in a plurality of modular types which have different resonant frequency bands, respectively.

A method for joining or machining, in particular a friction stir welding method, using an apparatus, in which a tool, in particular a friction stir welding tool, is driven via a spindle with a spindle axis. To achieve high process reliability, even when the method is applied in poorly accessible positions, an adapter, in particular an angle head, is arranged between the spindle and the tool so that the tool axis about which the tool rotates does not coincide with the spindle axis. A force acting on the spindle is measured and the method is controlled depending on the force measured at the spindle. The apparatus for joining or machining, in particular for friction stir welding, includes a headstock with a spindle, which can be rotated about a spindle axis and a tool, in particular a friction stir welding tool, which can be driven about a tool axis by the spindle.

A handheld cut-off saw (300) for cutting concrete and stone, the handheld cut-off saw comprising a drive arrangement (100, 200, 600, 800) for driving a circular cutting tool (110), the drive arrangement comprising: a belt drive portion (120) comprising a first pulley (121) and a second pulley (122), wherein the first pulley is arranged to be powered by a power source (130) and to drive the second pulley via a belt (123), wherein the second pulley (122) has a larger pitch diameter than the first pulley (121); and a gear transmission portion (140) comprising a first gearwheel (141) and a second gearwheel (142), wherein the first gearwheel (141) is co-axially connected to the second pulley (122) and radially connected to the second gearwheel (142), and wherein the second gearwheel (142) is arranged to be co-axially connected to the circular cutting tool (110).