A guide bush control device includes a guide bush motor that rotates and drives a guide bush; and a controller that controls driving of the guide bush motor, the guide bush control device controlling rotation of the guide bush by controlling the driving of the guide bush motor with the controller, wherein the controller includes a fixing unit that fixes the guide bush non-rotatably by exciting the guide bush motor in a rotation stop state.

A guide bush control device includes a guide bush motor that rotates and drives a guide bush; and a controller that controls driving of the guide bush motor, the guide bush control device controlling rotation of the guide bush by controlling the driving of the guide bush motor with the controller, wherein the controller includes a fixing unit that fixes the guide bush non-rotatably by exciting the guide bush motor in a rotation stop state.

The invention provides a machine tool eliminating the need of keeping the removed feed-mechanism-protection cover outside the machine. The machine tool comprises a headstock provided with a main spindle for gripping a workpiece; a driving unit provided with a feed mechanism extended along a main spindle axis to move the headstock in a main spindle axial direction; a supporting bed provided with a guide bush in a removable manner; a first cover mounted on the headstock to protect a portion of the feed mechanism with respect to the main spindle axial direction; and a second cover removably mounted on the headstock on the front side of the first cover to protect another portion of the feed mechanism. The second cover is detachably attached to the first cover when removed from the headstock.

The invention provides a machine tool eliminating the need of keeping the removed feed-mechanism-protection cover outside the machine. The machine tool comprises a headstock provided with a main spindle for gripping a workpiece; a driving unit provided with a feed mechanism extended along a main spindle axis to move the headstock in a main spindle axial direction; a supporting bed provided with a guide bush in a removable manner; a first cover mounted on the headstock to protect a portion of the feed mechanism with respect to the main spindle axial direction; and a second cover removably mounted on the headstock on the front side of the first cover to protect another portion of the feed mechanism. The second cover is detachably attached to the first cover when removed from the headstock.

A main spindle located in a region of a rotary guide bush device where the rotary guide bush device (has been attached to be disposed in a position of a front (F) along an axis (C) direction when the rotary guide bush device having a guide bush, which is supported in a removable manner by a guide bush-supporting base (supporting base) provided in the front (F) along the axis (C) direction of the main spindle, is removed. A seal member (fixed to the guide bush-supporting base has contact with an outer circumferential surface of a main spindle cover over an entire circumference, so that processing with or without the guide bush can be selected and a complicated process required for switching the processing with or without the guide bush can be simplified.

A main spindle located in a region of a rotary guide bush device where the rotary guide bush device (has been attached to be disposed in a position of a front (F) along an axis (C) direction when the rotary guide bush device having a guide bush, which is supported in a removable manner by a guide bush-supporting base (supporting base) provided in the front (F) along the axis (C) direction of the main spindle, is removed. A seal member (fixed to the guide bush-supporting base has contact with an outer circumferential surface of a main spindle cover over an entire circumference, so that processing with or without the guide bush can be selected and a complicated process required for switching the processing with or without the guide bush can be simplified.

A lathe capable of facilitating maintenance of a chucking mechanism. A chuck operating apparatus includes a claw and a shifter to open and close a chuck provided on a spindle. The tilt claw provided outside the spindle has a first posture to bring the chuck into the opened state and a second posture to bring the chuck into the closed state. The shifter provided outside the spindle and movable in a spindle axis direction is brought in a first position to bring the claw into the first posture and in a second position to bring the claw into the second posture. A roller is mounted on the shifter in a contact position with the claw to roll in the spindle axis direction.

A chuck operating apparatus includes a claw, a shifter, and a shifter drive unit. The rotatable claw has a first posture to bring the chuck into the opened state and a second posture to bring the chuck into the closed state. The rotatable shifter is brought in a first position to bring the claw into the first posture and in a second position to bring the claw into the second posture. The shifter drive unit has a shifter lever having an insertion part provided with a shifter bearing capable of being brought into contact with a side surface of an outward groove of the shifter. A roller is provided on one of the claw and the shifter in a contact position with the other to roll in a spindle axis direction and a groove is formed on the other to receive the roller when the chuck is in the opened state.