A counter bearing for machining spindles of machine tools has at least one expansion bushing with an elastically deformable wall that delimits at least one pressure chamber. The pressure chamber accommodates a pressure medium. A supply line for the pressure medium opens into the pressure chamber. A pressure conduit opens into the pressure chamber. A mechanically actuatable pressure element is disposed in the pressure conduit and actuated by an actuating tool. A piston is slidably arranged in the pressure conduit and actuated by the pressure element, wherein the piston loads the pressure medium.

A tool holder for ultrasonic machining used in a machine which supplies power via a spindle is provided with a connector received in the spindle; a conductive ring disposed on the connector and electrically connected to the spindle so as that power is configured to supply to the tool holder; a tool mounting member including an axial hole for fastening a portion of a tool; and an oscillator for producing ultrasonic vibration disposed in the tool mounting member, the oscillator for producing ultrasonic vibration electrically connected to the conductive ring so that power supplied to the oscillator for producing ultrasonic vibration is configured to produce ultrasonic vibration of high frequency. The produced ultrasonic vibration of high frequency is transmitted to the tool via the axial hole.

A tool holder for ultrasonic machining used in a machine which supplies power via a spindle is provided with a connector received in the spindle; a conductive ring disposed on the connector and electrically connected to the spindle so as that power is configured to supply to the tool holder; a tool mounting member including an axial hole for fastening a portion of a tool; and an oscillator for producing ultrasonic vibration disposed in the tool mounting member, the oscillator for producing ultrasonic vibration electrically connected to the conductive ring so that power supplied to the oscillator for producing ultrasonic vibration is configured to produce ultrasonic vibration of high frequency. The produced ultrasonic vibration of high frequency is transmitted to the tool via the axial hole.

A modular tool holder for ultrasonic machining used in a machine which supplies power via a spindle is provided with a connector in the spindle; a conductive ring on the connector and electrically connected to the spindle; a tool mounting member including an axial hole; an oscillator for producing ultrasonic vibration in the tool mounting member and electrically connected to the conductive ring so that power supplied to the oscillator may produce ultrasonic vibration of high frequency; and a chuck releasably secured to an end of the axial hole.

A modular tool holder for ultrasonic machining used in a machine which supplies power via a spindle is provided with a connector in the spindle; a conductive ring on the connector and electrically connected to the spindle; a tool mounting member including an axial hole; an oscillator for producing ultrasonic vibration in the tool mounting member and electrically connected to the conductive ring so that power supplied to the oscillator may produce ultrasonic vibration of high frequency; and a chuck releasably secured to an end of the axial hole.

Systems and methods are provided for automatic tool loading of a milling machine. One embodiment is an apparatus for loading tools into a milling machine. The apparatus includes a base platform configured to rest on a table of the milling machine, and a support column extending vertically from the base platform. The apparatus also includes a holding member slidably coupled with the support column above the base platform, the holding member extending horizontally from the support column and configured to translate vertically along the support column, and to support a tool holder in an upright position for loading the tool holder into a spindle of the milling machine.

A cutter holder has a body and a retention knob connected to the body by threading. The body has a connecting hole having an internal threaded segment and a straight segment. The retention knob has a head, an abutting portion, and an external threaded portion. The abutting portion has a flange and an extending portion. The extending portion and the straight segment are in a clearance fit, and a sealing member seals the clearance between the extending portion and the straight segment. The external threaded portion is engaged with the internal threaded segment by threading, and has a first threaded segment and a second threaded segment. The first threaded segment is away from the head of the retention knob, and a tolerance class of the second threaded segment is higher than a tolerance class of the first threaded segment.

A clamping device for clamping a workpiece or a tool or, more specifically, a tool holding fixture in a machine part of a machine tool includes a tension rod slidably mounted within the machine part; a clamping set movable by the tension rod between clamped and released positions; a tension spring dedicated to the tension rod so as to generate the pull-in force of the clamping set; and a release mechanism, by which the clamping set can be moved against the force of the tension spring into the released position by the tension rod. To make possible effective clamping at optimum force, the tension spring is clamped between first and second rod parts of the tension rod. The second rod part can move relative to the first rod part, and, as the clamping set moves into the released position, is compressed on both ends by the release mechanism by moving the two rod parts in opposite directions.

A rotating-tool main shaft includes a hollow ram, a hollow main shaft, a collet, a draw bar that moves the collet in the axial direction, a hydraulic cylinder that moves forwardly the draw bar, and a disc spring that moves backwardly the draw bar. The draw bar includes a spring catch which is retained in the hollow main shaft so as to be movable, and which catches the disc spring. The disc spring is placed in the hollow main shaft, and is placed within a distance that is at least a half of a distance from a tip of the draw bar to the spring catch in the axial direction.

A spindle unit for machine tools that includes a working spindle rotationally bearing-mounted in axially spaced spindle bearings in a spindle case, and an electric driving motor. The working spindle includes at its head side a clamping device for a tool and at its rear side a non-rotating ring cylinder for activating said clamping device via a rotating tie rod, and rotational bushing for supplying said tool with cooling and/or lubricating agents through a hydraulic conduit extending longitudinally through said working spindle. At least a segment of the non-rotating ring cylinder may be received in the rear end portion of said working spindle.