Abstract: A lathe 1 includes a first tool rest 10 and a second tool rest 20 disposed to face each other with a spindle axis between them and is configured to, when machining a workpiece W with a tool attached to the first tool rest 10, support the portion to be machined of the workpiece W at a side opposite to the portion to be machined of the workpiece W with a support member 28 attached to the second tool rest 20. A servo motor 24 that moves the second tool rest 20 when supporting the workpiece W is supplied with a current within a preset limiting range. The limiting range is previously set based on a current value detected by driving the servo motor 24 to move the second tool rest 20 and detecting a value of a current supplied to the servo motor 24 during the movement.

Abstract: A machine tool re-machines a workpiece after positioning drive motors, a hob and the workpiece by stopping the drive motors with the rotational positions of the drive motors, the hob and the workpiece corresponding to their respective zero positions. For this purpose, a drive control section recognizes, based on the rotational-speed ratio of the drive motor corresponding to the hob and the hob and/or the rotational-speed ratio of the drive motor corresponding to the workpiece to the workpiece, and detection signals from detection sensors detecting that the rotational positions of the drive motors are at their respective zero positions, detections signals when the rotational positions of the drive motors and the rotational positions of the hob and the workpiece correspond to their respective zero positions, and stops the drive motors with the rotational positions of the drive motors, the hob and the workpiece corresponding to their respective zero positions.

Abstract: A control device of a machine tool includes a first determination unit determining an amount of rotation, rotational speed, and direction of rotation of a rotary handle based on a pulse signal generated by rotation of the rotary handle at a manual pulse generator, and a second determination unit determining which of position control and rotational speed control is selected by selection of an axis through an axis selector switch, based on a signal generated by an axis selection signal generator at an operation device including the manual pulse generator. When a determination is made that position control is selected, the control device controls the amount and direction of travel of a spindle based on the amount of rotation and direction of rotation of the rotary handle. When a determination is made that rotational speed control is selected, the control device controls the rotational speed and direction of rotation of a table based on the rotational speed and direction of rotation of the rotary handle.

Abstract: A machine tool re-machines a workpiece after positioning drive motors, a hob and the workpiece by stopping the drive motors with the rotational positions of the drive motors, the hob and the workpiece corresponding to their respective zero positions. For this purpose, a drive control section recognizes, based on the rotational-speed ratio of the drive motor corresponding to the hob and the hob and/or the rotational-speed ratio of the drive motor corresponding to the workpiece to the workpiece, and detection signals from detection sensors detecting that the rotational positions of the drive motors are at their respective zero positions, detections signals when the rotational positions of the drive motors and the rotational positions of the hob and the workpiece correspond to their respective zero positions, and stops the drive motors with the rotational positions of the drive motors, the hob and the workpiece corresponding to their respective zero positions.

Abstract: A control device of a machine tool includes a first determination unit determining an amount of rotation, rotational speed, and direction of rotation of a rotary handle based on a pulse signal generated by rotation of the rotary handle at a manual pulse generator, and a second determination unit determining which of position control and rotational speed control is selected by selection of an axis through an axis selector switch, based on a signal generated by an axis selection signal generator at an operation device including the manual pulse generator. When a determination is made that position control is selected, the control device controls the amount and direction of travel of a spindle based on the amount of rotation and direction of rotation of the rotary handle. When a determination is made that rotational speed control is selected, the control device controls the rotational speed and direction of rotation of a table based on the rotational speed and direction of rotation of the rotary handle.