Abstract: The invention provides an improved drain structure of a cutting fluid supplied to a spindle of a milling spindle. The milling spindle 100 comprises a spindle 20 supported within a housing via a bearing 16, and a drawbar 24 having a through coolant passage 22. The cutting fluid C1 passing through the rotary joint 40 and 50 is sent to the through coolant passage 22, but a portion thereof is collected in a drain chamber 110. When the pressure within the drain chamber rises, the drain device 150 pushes open the ball 160 resisting against the spring 170, and the cutting fluid C1 is discharged to the exterior.

Abstract: The invention provides an improved seal structure of cutting fluid supplied to a spindle of a milling spindle. The milling spindle 100 comprises a spindle 20 supported within a housing via a bearing 16, and a drawbar 24 having a through coolant passage 22. The cutting fluid C1 passing through the rotary joint 40 and 50 is sent to the through coolant passage 22, but a portion thereof is collected in a drain chamber 105. A rotation member 110 is attached to a rear end portion of the spindle 20, which is equipped with a labyrinth device 150 having a lip seal member 152. An air supply member 120 has two air seal members 142 and 144, and air A1 is sent toward the labyrinth device 150, by which an air seal is formed.

Abstract: It is an object of the invention to provide a technique for further improving the vibration reducing performance in an impact tool. A representative impact tool includes a tool body, a cylinder housed within the tool body, a dynamic vibration reducer having a weight that linearly moves under a biasing force of an elastic element, wherein the dynamic vibration reducer reduces vibration of the tool body during hammering operation by the movement of the weight in the axial direction of the tool bit, and a mechanical vibration mechanism that actively drives the weight by applying external force other than vibration of the tool body to the weight via the elastic element. The weight and the elastic element are disposed on the axis of the tool bit and between an inner wall surface of the tool body and an outer wall surface of the cylinder in such a manner as to cover at least part of the outer wall surface of the cylinder in the circumferential direction.

Abstract: It is an object of the invention to provide an effective technique for further enhancing the effect of reducing a reaction force inputted during hammering operation. Representative impact tool comprises a tool body, a hammer actuating member, a cylinder and a compression coil spring. The compression coil spring contacts the hammer actuating member and thereby positions the tool body with respect to the workpiece when the hammer actuating member is pressed against the workpiece and pushed rearward in advance of the hammering operation. In such position, the compression coil spring absorbs a reaction force that is caused by rebound from the workpiece and acts upon the hammer actuating member when the hammer actuating member performs the hammering operation on the workpiece. The cylinder is inserted into the tool body from the front along the axial direction of the hammer actuating member and thereby housed within a predetermined housing part of the tool body.

Abstract: An electric hammer comprising a hammer bit performing hammering work on a work, a drive motor, a hammering piece driven by the drive motor to apply a hammering force to the hammer bit, and a mechanism for damping vibration generated during hammering. The damping performance of the electric hammer is enhanced by causing the driving amount applied to the damping mechanism to vary between a first mode where the damping mechanism generates vibration of the hammer bit subjected to an external force from the work during the load driving time and thereby optimizes the damping and a second mode where the damping mechanism generates vibration corresponding to the vibration of the hammer bit not subjected to an external force from the work during the no-land driving time and optimizes damping.

Abstract: It is an object of the invention to reduce noise caused by run-out of a tool bit in an impact tool. The representative impact tool according to the invention includes a tool holder 137 that houses a tool bit 119 in such a manner that the tool bit can linearly move in its axial direction, and a barrel 108 that is integrally connected to the tool holder 137 The impact tool further includes an elastic element 155 that is disposed between an inner circumferential surface of the tool holder 137 and an outer circumferential surface of the tool bit 119 in an end region of the tool bit 119 on the barrel side and connected in close contact with the tool holder 137 and the tool bit 119 over a predetermined length of the tool bit 119 in the axial direction. The elastic element 155 applies a biasing force to prevent a run-out of the tool bit 119 in a direction transverse to the axial direction. Further, an intermediate element 145 comes in point contact with the tool bit 119 on its axial center line.

Abstract: An electric hammer comprising a hammer bit (313) performing hammering work on a work, a drive motor, a hammering piece (334) driven by the drive motor to apply a hammering force to the hammer bit, and a mechanism (371) for damping vibration generated during hammering. The damping performance of the electric hammer is enhanced by causing the driving amount applied to the damping mechanism (371) to vary between a first mode where the damping mechanism (371) generates vibration of the hammer bit (313) subjected to an external force from the work during the load driving time and thereby optimizes the damping and a second mode where the damping mechanism (371) generates vibration corresponding to the vibration of the hammer bit (313) not subjected to an external force from the work during the no-land driving time and optimizes damping.

Abstract: The invention provides an improved seal structure of cutting fluid supplied to a spindle of a milling spindle. The milling spindle 100 comprises a spindle 20 supported within a housing via a bearing 16, and a drawbar 24 having a through coolant passage 22. The cutting fluid C1 passing through the rotary joint 40 and 50 is sent to the through coolant passage 22, but a portion thereof is collected in a drain chamber 105. A rotation member 110 is attached to a rear end portion of the spindle 20, which is equipped with a labyrinth device 150 having a lip seal member 152. An air supply member 120 has two air seal members 142 and 144, and air A1 is sent toward the labyrinth device 150, by which an air seal is formed.

Abstract: The invention provides an improved drain structure of a cutting fluid supplied to a spindle of a milling spindle. The milling spindle 100 comprises a spindle 20 supported within a housing via a bearing 16, and a drawbar 24 having a through coolant passage 22. The cutting fluid C1 passing through the rotary joint 40 and 50 is sent to the through coolant passage 22, but a portion thereof is collected in a drain chamber 110. When the pressure within the drain chamber rises, the drain device 150 pushes open the ball 160 resisting against the spring 170, and the cutting fluid C1 is discharged to the exterior.

Abstract: The invention provides a power tool which includes a tool bit, a first operating mechanism that linearly drives the tool bit and thereby causes the tool bit to perform a predetermined operation, and a dynamic vibration reducer 151 that reduces vibration in the operation of the tool bit. The dynamic vibration reducer includes a weight 153 that can linearly move under the action of biasing forces of a plurality of biasing springs 157 acting upon the weight 153 toward each other. The weight 153 is driven by a second operating mechanism 116 that mechanically excites at least one of the elastic elements, via the elastic element.

Abstract: It is an object of the invention to provide an effective technique for improving the durability of a torque limiter utilized in a power tool. The object is achieved by a representative power tool comprising a tool bit, a driving mechanism and a torque limiter. The torque limiter includes first and second rotating members, a ball, a pressing member and an elastic member. The second rotating member includes a power transmitting region with a groove continuously formed from a deepest groove part to a shallowest groove part to allow torque transmission and a power transmission interrupted region with a groove shallower than the shallowest groove part of the power transmitting region to interrupts the torque transmission. According to this construction, when the ball is in the power transmitting region, the pressing member contacts the first rotating member and is held in a position in which the biasing force of the elastic member is prevented from acting upon the ball.

Abstract: It is an object of the invention to provide a technique that contributes to further improvement of an impact tool. A representative impact tool includes a motor, a tool body that houses the motor, a dynamic vibration reducer and a driving mechanism part that is driven by the motor and forcibly drives the dynamic vibration reducer by applying an external force other than vibration of the tool body to the dynamic vibration reducer, during hammering operation. At least one of the dynamic vibration reducer and the driving mechanism part is mounted to the tool body in a form of an assembly into which at least one of a plurality of component parts forming the dynamic vibration reducer and a plurality of component parts forming the driving mechanism part are assembled in advance.

Abstract: An electric hammer comprising a hammer bit (313) performing hammering work on a work, a drive motor, a hammering piece (334) driven by the drive motor to apply a hammering force to the hammer bit, and a mechanism (371) for damping vibration generated during hammering. The damping performance of the electric hammer is enhanced by causing the driving amount applied to the damping mechanism (371) to vary between a first mode where the damping mechanism (371) generates vibration of the hammer bit (313) subjected to an external force from the work during the load driving time and thereby optimizes the damping and a second mode where the damping mechanism (371) generates vibration corresponding to the vibration of the hammer bit (313) not subjected to an external force from the work during the no-land driving time and optimizes damping.

Abstract: It is an object of the invention to provide a technique for further improving the vibration reducing performance in an impact tool. A representative impact tool includes a tool body, a cylinder housed within the tool body, a dynamic vibration reducer having a weight that linearly moves under a biasing force of an elastic element, wherein the dynamic vibration reducer reduces vibration of the tool body during hammering operation by the movement of the weight in the axial direction of the tool bit, and a mechanical vibration mechanism that actively drives the weight by applying external force other than vibration of the tool body to the weight via the elastic element. The weight and the elastic element are disposed on the axis of the tool bit and between an inner wall surface of the tool body and an outer wall surface of the cylinder in such a manner as to cover at least part of the outer wall surface of the cylinder in the circumferential direction.

Abstract: It is an object of the invention to provide an effective technique for further enhancing the effect of reducing a reaction force inputted during hammering operation. Representative impact tool comprises a tool body, a hammer actuating member, a cylinder and a compression coil spring. The compression coil spring contacts the hammer actuating member and thereby positions the tool body with respect to the workpiece when the hammer actuating member is pressed against the workpiece and pushed rearward in advance of the hammering operation. In such position, the compression coil spring absorbs a reaction force that is caused by rebound from the workpiece and acts upon the hammer actuating member when the hammer actuating member performs the hammering operation on the workpiece. The cylinder is inserted into the tool body from the front along the axial direction of the hammer actuating member and thereby housed within a predetermined housing part of the tool body.

Abstract: It is an object of the invention to provide a technique that contributes to rationalization of a mechanism relating to reduction of vibration in an impact tool. Representative impact tool includes a tool body, a hammer actuating member, a dynamic vibration reducer and a positioning elastic element. The positioning elastic element contacts the hammer actuating member and thereby positions the tool body with respect to the workpiece so as to absorb a reaction force caused by rebound from the workpiece and acts on the hammer actuating member when the hammer actuating member performs the hammering operation on the workpiece. The positioning elastic element includes the elastic element formed as a component part of the dynamic vibration reducer.

Abstract: [Problem] To provide an effective technique for further improving the vibration reducing performance of a power tool. [Means for Solving the Problem] The invention provides a power tool which includes a tool bit, a first operating mechanism that linearly drives the tool bit and thereby causes the tool bit to perform a predetermined operation, and a dynamic vibration reducer 151 that reduces vibration in the operation of the tool bit. The dynamic vibration reducer includes a weight 153 that can linearly move under the action of biasing forces of a plurality of biasing springs 157 acting upon the weight 153 toward each other. The weight 153 is driven by a second operating mechanism 116 that mechanically excites at least one of the elastic elements, via the elastic element.

Abstract: It is an object of the invention to provide an effective technique for improving the durability of a torque limiter utilized in a power tool. The object is achieved by a representative power tool comprising a tool bit, a driving mechanism and a torque limiter. The torque limiter includes first and second rotating members, a ball, a pressing member and an elastic member. The second rotating member includes a power transmitting region with a groove continuously formed from a deepest groove part to a shallowest groove part to allow torque transmission and a power transmission interrupted region with a groove shallower than the shallowest groove part of the power transmitting region to interrupts the torque transmission. According to this construction, when the ball is in the power transmitting region, the pressing member contacts the first rotating member and is held in a position in which the biasing force of the elastic member is prevented from acting upon the ball.

Abstract: It is an object of the invention to provide a reciprocating power tool having a further improved power transmitting mechanism for converting a rotating output of a driving motor into linear motion in the axial direction of the tool bit. The representative reciprocating power tool may comprise a tool bit, a driving motor and a power transmitting mechanism that converts a rotating output of the driving motor into linear motion in the axial direction of the tool bit. The power transmitting mechanism includes an internal gear, a planerary gear, a power transmitting part, a rotation preventing mechanism and an internal gear rotation lock. Further, an internal gear rotation lock prevents the internal gear from rotating in a direction opposite to said predetermined direction. Therefore, the internal gear rotated only in one direction via the internal gear rotation lock and as a result, the internal gear can be reliably locked in a predetermined position without causing rattling.

Abstract: It is an object of the invention to provide a technique for further improving the vibration reducing performance in the power tool, while avoiding complicating the construction of the power tool. According to the present invention, a representative power tool may comprise a striker, a tool bit and a vibration reducer. The vibration reducer serves to reduce vibration on the striker by reciprocating in a direction opposite to the reciprocating direction of the striker. The path of the center of gravity of the vibration reducer is arranged to coincide with a path of the center of gravity of the striker. With such construction, because rotating moment is not exerted onto the reciprocating cylinder during the operation of the power tool, vibration reduction can be performed in a stable manner.