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.

An improved spindle assembly for a Davenport multi-axis screw machine is adapted to adequately hold one-inch round bar-stock in a collet against movement relative thereto attributable to machining operations performed on a cantilevered length of bar-stock held in and extending beyond the collet. The spindle assembly may permit the use of the screw machine on materials thought heretofore to be too difficult to machine on a screw machine. Cam surfaces on the inner spindle and collet may be coated with a low-friction material. A stress-relieving connection between the inner spindle and collet is provided.

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.

An apparatus for feeding bars to a machine tool including an end adjacent a working zone in which a spindle is provided; a drum element, rotatable around an axis; a movable support provided on the drum element for supporting and guiding a bar parallel to the axis. The movable support slidably drivable on the drum element parallel to the axis between a disengagement retracted configuration and an engagement extended configuration. The movable support having telescopic tube configured for being received inside tubular housing and guide for coupling with the spindle. The telescopic tube defines, a cylindrical containing structure configured for enclosing and supporting in a distributed manner a respective bar along the entire supporting zone, so as to prevent the bar from flexing because of the centrifugal actions generated by rotation.

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 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.

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.