Automatic centering center rest for lathe

The utility model relates to an automatic centering center rest for lathe, having compact conformation, simple operation, accurate centering, rapidity, and effective improvement of the working efficiency. The utility model comprises an upper and a lower frame body, and between them, an opening/closing body is provided, and three centering elements are uniformly distributed on the upper and lower frame bodies; the centering element comprises a roller arranged in the space constructed by body elements and closing plates, and flat spiral engaged with a flat plate in the space, and the front end of the roller is equipped with a rolling bearing; the upper frame body is fixed with a gearbox provided with gears and rotating shafts connected by flat keys, and engaged with the excircle gears of the flat plate; the front end of the roller is equipped with an eccentric axis and an eccentric sleeve; and the centering element is equipped with a jack screw simultaneously acting on the eccentric axis and the jack screw groove corresponding to the excircle of the eccentric sleeve.