Lathe positioning apparatus

A lathe positioning apparatus for positioning a chucked work in a main shaft direction, the lathe positioning apparatus comprising:

• an apparatus body having a shaft center along the main shaft direction and arranged such that an abutting portion that abuts the work is formed on a chuck-side end of the apparatus body;
• and
• an extension/contraction mechanism provided inside said apparatus body to advance or withdraw the abutting portion with respect to a chuck by extending or contracting the apparatus body in the main shaft direction,
• wherein said apparatus body has the same shaft center as the main shaft, and extending or contracting of the apparatus body is provided on the shaft center of the main shaft by said extension/contraction mechanism,
• said apparatus body has a fixed body and a movable body both having the same shaft center as the main shaft, said fixed body is axially fixed in position, said movable body is connected to the fixed body slidably in the main shaft direction, and said extension/contraction mechanism is provided to change a length of said apparatus body in the main shaft direction by moving said movable body slidably in the main shaft direction with respect to the fixed body,
• said extension/contraction mechanism has a screw mechanism for moving said movable body slidably in the main shaft direction with respect to the fixed body, and an operation shaft arranged inside said fixed body so as to have the same shaft center as said fixed body in order to actuate the screw mechanism by rotation about an axis of the operation shaft itself,
• the chuck is attached to one end of the main shaft and a chuck cylinder is attached to another end of the main shaft, a chuck cylinder side end of the operation shaft is provided to rotate the operation shaft about an axis of the operation shaft itself, and the chuck cylinder is provided to permit the work to be held or released by the chuck.