A machine tool includes: a cutting tool; rotating means; feeding means; and vibration means for reciprocatingly vibrating the cutting tool and the workpiece relative to each other; wherein the cutting process is carried out by a relative rotation of the workpiece and the cutting tool, and feeding of the cutting tool, to thereby move the cutting tool continuously along a plurality of predetermined movement paths each having a different machining feeding direction. The machine tool further includes vibration restriction means that operates as the movement of the cutting tool changes from one movement path of two consecutive movement paths to the other movement path, for restricting the reciprocating vibration for a predetermined period from the movement starting position of the movement paths, and starting the reciprocating vibration after the lapse of said predetermined period.

A control device for a machine tool and a machine tool, for which settings of the number of vibrations per rotation become easy, is provided. The control device of the machine tool controls a relative rotation between a workpiece and a cutting tool and a relative reciprocal movement between the workpiece and the cutting tool in a feed direction to perform vibration cutting to the workpiece. The control device includes a control section for controlling a spindle headstock, a first tool post, and a second tool post, the workpiece W being installed on the spindle headstock, the first tool post being provided to be reciprocally movable along the feed direction with respect to the spindle headstock and installed with a first cutting tool for cutting the workpiece, and the second tool post being provided to be reciprocally movable along the feed direction with respect to the spindle headstock independently of the first tool post and installed with a second cutting tool for cutting the workpiece.

An estimating device estimating a rotary axis position of a workpiece includes first and second position acquisition units acquiring tool positions in first and second directions, a load acquisition unit acquiring first and second directional loads of the tool in the first and second directions, a determination unit determining whether or not the first and second directional loads each are a threshold or less, a turning control unit performing a lathe turning on the workpiece until the first directional load becomes the threshold or less and thereafter performing a lathe turning thereon until the second directional load becomes the threshold or less, and an estimating unit estimating the rotary axis position based on a first directional position of the tool when the first directional load has become the threshold or less, and a second directional position thereof when the second directional load has become the threshold or less.

An estimating device estimating a rotary axis position of a workpiece includes first and second position acquisition units acquiring tool positions in first and second directions, a load acquisition unit acquiring first and second directional loads of the tool in the first and second directions, a determination unit determining whether or not the first and second directional loads each are a threshold or less, a turning control unit performing a lathe turning on the workpiece until the first directional load becomes the threshold or less and thereafter performing a lathe turning thereon until the second directional load becomes the threshold or less, and an estimating unit estimating the rotary axis position based on a first directional position of the tool when the first directional load has become the threshold or less, and a second directional position thereof when the second directional load has become the threshold or less.

A machine tool includes: a cutting tool; rotating means; feeding means; and vibration means for reciprocatingly vibrating the cutting tool and the workpiece relative to each other; wherein the cutting process is carried out by a relative rotation of the workpiece and the cutting tool, and feeding of the cutting tool, to thereby move the cutting tool continuously along a plurality of predetermined movement paths each having a different machining feeding direction. The machine tool further includes vibration restriction means that operates as the movement of the cutting tool changes from one movement path of two consecutive movement paths to the other movement path, for restricting the reciprocating vibration for a predetermined period from the movement starting position of the movement paths, and starting the reciprocating vibration after the lapse of said predetermined period.

A control device for a machine tool and a machine tool, for which settings of the number of vibrations per rotation become easy, is provided. The control device of the machine tool controls a relative rotation between a workpiece and a cutting tool and a relative reciprocal movement between the workpiece and the cutting tool in a feed direction to perform vibration cutting to the workpiece. The control device includes a control section for controlling a spindle headstock, a first tool post, and a second tool post, the workpiece W being installed on the spindle headstock, the first tool post being provided to be reciprocally movable along the feed direction with respect to the spindle headstock and installed with a first cutting tool for cutting the workpiece, and the second tool post being provided to be reciprocally movable along the feed direction with respect to the spindle headstock independently of the first tool post and installed with a second cutting tool for cutting the workpiece.