Provided is a machine tool that makes it possible to prevent a reduction in accuracy of a lathe turning process. The machine tool holds a lathe turning tool by means of a tool holder attached to a main shaft and processes a workpiece placed on a rotating table with the lathe turning tool. The machine tool is provided with a fixing member (a gripping member, a pin, a plate) that comes into contact with the main shaft or the tool holder to inhibit rotation of the main shaft and the tool holder.

In order to provide a tool changer that can detect an entry of a foreign substance into a turret mechanism portion or wear of a turret mechanism part, a tool changer of the present invention includes a reference phase false detection sensing portion that monitors load variations which occur in a turret drive source and detects an entry of a foreign substance into the turret mechanism portion based on a difference between the load variations and a reference load used as a reference. Moreover, the reference phase false detection sensing portion can also detect the progress of wear of the turret mechanism part based on the integral of the absolute value of a difference between the load variations which occur in the turret drive source and the reference load used as a reference.

A workpiece holder device for workpieces to be machined on multiple sides, wherein the workpiece can be held axially and radially relative to the first axis between a first workpiece holder, operatively connected to at least one support spindle of the workpiece holder device and rotatable about the first axis, and at least one second workpiece holder, operatively connected to at least one drive spindle of the workpiece holder device and rotatable about the first axis, by force locking by means of a clamping force which can be built up in the manner of a vice between the first workpiece holder and the second workpiece holder in the axial direction of the first axis and acting on the opposite sides of the workpiece.

A machine tool includes a turning position adjustment unit configured to control a turning drive unit so that, when a tool is transferred between a spindle and a grip, if an amount of sway of the tool is greater than or equal to a threshold value, a turret is turned and the amount of sway of the tool becomes less than the threshold value, and an origin point correcting unit configured to correct an origin point in accordance with a turning position of the turret acquired by a turning position acquisition unit, when the turret is turned by the turning drive unit so that the amount of sway of the tool becomes less than the threshold value.

A workpiece holder device for workpieces to be machined on multiple sides, wherein the workpiece can be held axially and radially relative to the first axis between a first workpiece holder, operatively connected to at least one support spindle of the workpiece holder device and rotatable about the first axis, and at least one second workpiece holder, operatively connected to at least one drive spindle of the workpiece holder device and rotatable about the first axis, by force locking by means of a clamping force which can be built up in the manner of a vice between the first workpiece holder and the second workpiece holder in the axial direction of the first axis and acting on the opposite sides of the workpiece.

A machine tool includes a turning position adjustment unit configured to control a turning drive unit so that, when a tool is transferred between a spindle and a grip, if an amount of sway of the tool is greater than or equal to a threshold value, a turret is turned and the amount of sway of the tool becomes less than the threshold value, and an origin point correcting unit configured to correct an origin point in accordance with a turning position of the turret acquired by a turning position acquisition unit, when the turret is turned by the turning drive unit so that the amount of sway of the tool becomes less than the threshold value.

A workpiece holder device for workpieces to be machined on multiple sides, wherein the workpiece can be held axially and radially relative to the first axis between a first workpiece holder, operatively connected to at least one support spindle of the workpiece holder device and rotatable about a first axis, and at least one second workpiece holder, operatively connected to at least one drive spindle of the workpiece holder device and rotatable around the first axis, by force locking by a clamping force which can be built up in the manner of a vice between the first workpiece holder and the second workpiece holder in the axial direction of the first axis and acting on the opposite sides of the workpiece.

In order to provide a tool changer that can detect an entry of a foreign substance into a turret mechanism portion or wear of a turret mechanism part, a tool changer of the present invention includes a reference phase false detection sensing portion that monitors load variations which occur in a turret drive source and detects an entry of a foreign substance into the turret mechanism portion based on a difference between the load variations and a reference load used as a reference. Moreover, the reference phase false detection sensing portion can also detect the progress of wear of the turret mechanism part based on the integral of the absolute value of a difference between the load variations which occur in the turret drive source and the reference load used as a reference.

A table clamp device includes a reference rail, a slider section, and a movement mechanism. The reference rail is provided on a mounting surface of a base on which a rotary table is rotatably supported. The rotary table has a first engagement part. The slider section is provided to slide along the reference rail and has a second engagement part. The movement mechanism moves the slider section along the reference rail so that the second engagement part engages with the first engagement part such that the rotary table is positioned and clamped to the base.

A table clamp device includes a reference rail, a slider section, and a movement mechanism. The reference rail is provided on a mounting surface of a base on which a rotary table is rotatably supported. The rotary table has a first engagement part. The slider section is provided to slide along the reference rail and has a second engagement part. The movement mechanism moves the slider section along the reference rail so that the second engagement part engages with the first engagement part such that the rotary table is positioned and clamped to the base.