Proposed is a machine tool unit with a stator unit and a rotor unit which is rotatable about an axis of rotation, wherein the rotor unit comprises a spindle head with a tool-holding unit having a tool-clamping device, wherein a testing device is provided for testing the clamping state of the tool, the testing device having precisely one sensor head for sensory detection. To improve the precision, the sensor head is arranged at a fixed position on the stator unit in such a manner that it measures the distance to an end-side part of the spindle head rotating relative to the sensor head, wherein the testing device is designed to record a temporal/position-related sequence of at least two distance values and/or of at least two successive series of in each case at least two distance values, in order to determine an axial run-out error.

There is proposed a method for examining the clamping state of a tool holder or tool which is clamped in a tool clamping device of a rotor unit of a motor-driven machine tool unit, with the spacing of the sensor head from a component of the rotor unit being measured, with a recording of at least one time and/or position-related sequence of the spacing values measured with the sensor head, wherein for improved integration of the method the recording of a first and a second time and/or position-related sequence is carried out during an acceleration of the rotation of the rotor unit with respect to the stator unit, in particular when the rotor unit is started up, wherein the time and/or position-related information of the sequence vectors of the first and/or second sequence is scaled using the respective associated current speed (v.sub.0).

A machine tool includes: a hollow spindle including a hollow portion along an axial direction; a plurality of chuck claws openably mounted at a distal end portion of the hollow spindle, and configured to hold a workpiece; an operation rod inserted into the hollow portion of the hollow spindle in a movable manner, and configured to close the plurality of chuck claws with movement of the operation rod toward one side in the axial direction and open the plurality of chuck claws with movement of the operation rod toward the other side in the axial direction; and a measuring apparatus configured to measure an opening dimension of the plurality of chuck claws based on a movement amount of the operation rod.

A workpiece holding device includes: a chuck including a chuck body, and a plurality of chuck claws openably supported on the chuck body and configured to hold a workpiece; an operation rod configured to drive the plurality of chuck claws for opening and closing with movement of the operation rod; and a measuring apparatus configured to measure an opening dimension of the plurality of chuck claws based on a movement amount of the operation rod.

An ascent-detecting air supply port (33), a descent-detecting air supply port (43), and an air discharge port (44) are provided to a housing (2). The ascent-detecting air supply port (33) is communicatively connected to an air outlet (38) by an ascent-detecting air passage (39). The descent-detecting air supply port (43) is communicatively connected to the air discharge port (44) by a descent-detecting air passage (45). The descent-detecting air passage (45) is closed by a valve mechanism (49) including: a valve surface (50) provided on a piston portion (15); and a valve seat (51) provided on an inner surface of the housing (2), when an advance piston (14) is retracted to a lowered position.

The present invention makes a rotary movement smooth, the rotary movement allowing direct detection of the movement of an output member of a rotary clamp. In a clamp, an output member is accommodated in a cylinder hole. A first valve chamber, to which compressed air is supplied, is provided between a lower wall of a housing and the output member. A second valve chamber is a hollowed out portion of the output member so as to be provided open toward the first valve chamber. A valve rod is inserted into the second valve chamber from the lower wall. A valve rod passage that allows the second valve chamber to communicate with outside air is provided in the valve rod, and a seal section is provided in a peripheral gap where the valve rod and the second valve chamber move relatively to one another. The gap is formed so that, as the valve rod and the second valve chamber are in relative movement, there is a region which is sealed by the seal section against movement of the compressed air through the gap between the valve rod and the second seal chamber and the there is a region which is open from the seal.

A plurality of detection valves (12 and 13) are provided to a housing (1), and at least one air passage (14 and 15), which communicatively connects the detection valves (12 and 13) to each other in series, are provided to the housing (1). One or some of the detection valves (12 and 13) are each configured as a throttle detection valve (13) including a throttle passage (56a).

A clamping apparatus is provided with: a metallic detector that is provided to a pivot shaft pivotally moving integrally with a clamp arm under the operation of a driving unit, in such a manner as to extend along the pivot shaft so as to be around the axis thereof; and one proximity sensor that is arranged so as to be opposed to the detector and that detects the magnetic loss of the detector. The detector is formed so that the area of a sensor opposing part opposed to a detection surface of the proximity sensor changes in association with the pivotal moving of the pivot shaft.

A position detecting device having a clamp body with a movable piston rod. A plurality of energy harvesting microswitches is mounted along a bottom of the piston rod using pin actuators to operate each microswitch depending on the piston rod position. The piston rod has a plurality of cutouts constructed and arranged to engage said pin actuators upon actuation of each microswitch, indicating a position which is transmitted wirelessly through the antenna. The antenna used to transmit a signal upon activation of a microswitch.

A motion error of a machine tool in a coordinate system having its origin at an arbitrary position is identified by means of error data measured by a commonly-used method. An X-axis feed mechanism, a Y-axis feed mechanism, and a Z-axis feed mechanism are operated in a three-dimensional space of a machine coordinate system to measure translational errors, angular errors, and perpendicularity errors thereof, and error data for translational error parameters, angular error parameters, and perpendicularity error parameters in a three-dimensional space of a set coordinate system having its origin at a preset reference position X.sub.a, Y.sub.a, Z.sub.a are derived based on the measured actual error data. Subsequently, a relative motion error between a spindle and a table in the three-dimensional space of the set coordinate system is derived based on the derived error data.