Polishing machine tool center bracket and using method

The invention discloses a center bracket of a polishing machine tool, and belongs to the field of polishing machine tools, the center bracket of the polishing machine tool comprises a supporting arm and a limiting mechanism, the inner side of the supporting arm is in a semi-arc shape, and the supporting arm is arranged on a lathe guide rail through a base and comprises a first frame body and a second frame body; the limiting mechanisms comprise a first limiting mechanism, a second limiting mechanism and a third limiting mechanism; a first limiting mechanism and a second limiting mechanism are arranged on the first frame body, the first limiting mechanism is arranged at the lower end part of the first frame body, the second limiting mechanism is arranged at the upper end part of the first frame body, and the second frame body is arranged at the upper part of the second limiting mechanism; the first limiting mechanism, the second limiting mechanism and the third limiting mechanism are located on the supporting