A tool holder assembly and insert body and activation system used with the assembly. The insert body of the tool holder assembly can be configured to shift as needed to engage tooling when the assembly is activated. In some cases, the insert body can be configured to shift further to better engage the tooling. The activation system can be electrical.

A flinger reducing a noise associated with rotation of an electric motor, and an electric motor with the flinger. The flinger fixed to a rotating shaft of the electric motor includes a plurality of tapped holes provided in an end face on an electric motor, and a cut-out cutting out a part of each of the tapped holes. The tapped hole of the flinger has a depth less than a depth of a tapped hole of a flinger in the related art by a distance equivalent to a depth of the cut-out, so that a natural frequency of an air column formed in the tapped hole increases. Thus, when the flinger is used, rotation speed causing increase in noise during rotation can be shifted to higher rotation speed.

A dental milling machine is provided with a tool which is guided in a chuck. A workpiece arm is mounted opposite the tool to be able to be moved at least in the direction of the spindle axis. With a control device it can be moved in relation to the workpiece, especially by means of a drive motor at the workpiece arm. The workpiece arm has an abutment element, whereby the control device moves the tool and the abutment element towards each other until they abut each other. The control device can be used to detect abutment of the abutment element with respect to the tool, in particular with respect to its tip, in particular by decelerating the (relative) movement of the tool and the abutment element towards each another, upon contact of the tool and the abutment element. This position may be signaled as a reference position and, especially may be stored.

A dental milling machine is provided with a tool which is guided in a chuck. A workpiece arm is mounted opposite the tool to be able to be moved at least in the direction of the spindle axis. With a control device it can be moved in relation to the workpiece, especially by means of a drive motor at the workpiece arm. The workpiece arm has an abutment element, whereby the control device moves the tool and the abutment element towards each other until they abut each other. The control device can be used to detect abutment of the abutment element with respect to the tool, in particular with respect to its tip, in particular by decelerating the (relative) movement of the tool and the abutment element towards each another, upon contact of the tool and the abutment element. This position may be signaled as a reference position and, especially may be stored.

A spindle device includes a spindle shaft, a spindle housing, and a chuck portion as a rotating member. The chuck portion has, formed therein, a suctioning passage through which air suctioned from the outside flows. The spindle shaft has a first guide passage which guides air flowing through the suctioning passage to a clearance between the inner wall of the spindle housing defining a through hole in which the spindle shaft is inserted and the outer wall of the spindle shaft facing the inner wall, by way of the interior of the spindle shaft. The spindle housing has, formed therein, a second guide passage configured to guide the air guided to the clearance, to the outside.

A spindle device includes a spindle shaft, a spindle housing, and a chuck portion as a rotating member. The chuck portion has, formed therein, a suctioning passage through which air suctioned from the outside flows. The spindle shaft has a first guide passage which guides air flowing through the suctioning passage to a clearance between the inner wall of the spindle housing defining a through hole in which the spindle shaft is inserted and the outer wall of the spindle shaft facing the inner wall, by way of the interior of the spindle shaft. The spindle housing has, formed therein, a second guide passage configured to guide the air guided to the clearance, to the outside.

A machine tool having a tool holder for exchangeably holding a tool is provided, the machine tool including: a machine tool housing; a spindle rotatably mounted in the machine tool housing a drive end being connected to a drive for rotating the spindle about an axis of rotation and a holding end being coupled to the tool holder; and a locking device arranged in the machine tool housing and which has a locking element reversibly movable between a release position and a locking position, a locking end of the locking element having an interlocking connector and the spindle having a mating interlocking connector, the interlocking connector being disengaged from the mating interlocking connector in the release position to enable rotational motion of the spindle, and the interlocking connector being engaged with the mating interlocking connector in the locking position to prevent rotational motion of the spindle and to enable an exchange of the tool of the tool holder, the locking device also including an electrically insulating mounting device for mounting the locking element in the machine tool housing to electrically insulate the locking element from the machine tool housing.

A machine tool having a tool holder for exchangeably holding a tool is provided, the machine tool including: a machine tool housing; a spindle rotatably mounted in the machine tool housing a drive end being connected to a drive for rotating the spindle about an axis of rotation and a holding end being coupled to the tool holder; and a locking device arranged in the machine tool housing and which has a locking element reversibly movable between a release position and a locking position, a locking end of the locking element having an interlocking connector and the spindle having a mating interlocking connector, the interlocking connector being disengaged from the mating interlocking connector in the release position to enable rotational motion of the spindle, and the interlocking connector being engaged with the mating interlocking connector in the locking position to prevent rotational motion of the spindle and to enable an exchange of the tool of the tool holder, the locking device also including an electrically insulating mounting device for mounting the locking element in the machine tool housing to electrically insulate the locking element from the machine tool housing.

A main shaft device is attached to a work machine. The main shaft device is provided with a main shaft that supports a tool or a workpiece, and a main shaft motor that causes the main shaft to rotate. The main shaft device is provided with bearings that are rolling bearings which support the main shaft in an inner race, and a housing and a rear housing that secure an outer race of the bearings. The housing and the rear housing are formed of a material having a coefficient of thermal expansion greater than that of the main shaft.

A main shaft device is attached to a work machine. The main shaft device is provided with a main shaft that supports a tool or a workpiece, and a main shaft motor that causes the main shaft to rotate. The main shaft device is provided with bearings that are rolling bearings which support the main shaft in an inner race, and a housing and a rear housing that secure an outer race of the bearings. The housing and the rear housing are formed of a material having a coefficient of thermal expansion greater than that of the main shaft.