A guide bush adjusting device includes a drawbar (a mobile body) displaceable relative to a guide bush sleeve (cylindrical body). The drawbar is formed from a screw connection member (a connection member) which is connected to a guide bush housed in the guide bush sleeve (a cylindrical body), and an operation member configured to displace the screw connection member. The guide bush adjusting device adjusts an inner diameter of the guide bush by releasing the operation member from its fixation, displacing the drawbar, moving the guide bush with respect to the guide bush sleeve via the drawbar to thereby position the guide bush, and fixing the operation member of the drawbar (mobile body) at a predetermined position.

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 machine tool includes: a joint portion processing control for controlling the processing of the joint portion in a joined workpiece such that a first workpiece is gripped by a grip section, and a predetermined region extending from a joint portion of a joined workpiece toward a second workpiece is processed over a range of not less than a predetermined width to have an outer diameter of not more than an outer diameter of the first workpiece; and a movement control for controlling the movement of the joined workpiece so as to slidingly move the joined workpiece relative to the support section, from a state in which the first workpiece is supported by the support section, up to a state in which the second workpiece is supported by the support section.

A machine tool has a front spindle that rotatably holds a bar, a front spindle drive motor that rotationally drives the front spindle, an encoder that detects a rotation angle of the front spindle drive motor, a rotary guide bush that is installed on a guide bush support in front of the front spindle to support the bar extending from the front spindle while allowing the bar to rotate around a rotation axis and move in a rotation axis direction and rotate synchronously with the front spindle, a back spindle that is arranged opposite to the front spindle and rotatably holds the bar, a back spindle drive motor that rotationally drives the back spindle, and a controller that controls operations of the front spindle and the back spindle.

A guide bush apparatus that supports a rod-shaped workpiece so that the workpiece is free to slide in the axis direction of the workpiece includes a guide bush sleeve, a guide bush that is disposed inside the guide bush sleeve, has a bush screw formed thereon, and has an inner diameter that changes in accordance with the relative position thereof relative to the guide bush sleeve in the axis direction, a retraction sleeve which is disposed inside the guide bush sleeve and on which a first screw that engages with the bush screw and a second screw having a different thread pitch from the first screw are formed, and a differential attachment/detachment body on which a differential screw that engages with the second screw is formed, and which can be fixed to and released from the guide bush sleeve.

An arrangement for forming grooves in a board element. The arrangement includes a support member for supporting the board element during the forming and cutting elements arranged on a spindle member configured to rotate around a rotational axis. The cutting elements are configured to form the grooves by removing material from the board element. The spindle member is arranged in a pivot body configured to be pivoted with respect to the support member. The arrangement includes a driving device configured to drive the pivot body, wherein the driving device is configured to rotate in a single direction during a groove forming cycle.