Positioning mandrel capable of effectively controlling coaxiality of outer surface of bearing bush and vibration damping groove

The utility model provides a positioning mandrel capable of effectively controlling the coaxiality of the outer surface of a bearing bush and a vibration damping groove. The positioning mandrel comprises a mandrel body, a flat nut and a threaded rod. The mandrel body is divided into three sections including a first mandrel polished rod, a second mandrel polished rod and a third mandrel polished rod in sequence; the positioning end face of the second mandrel polished rod is perpendicular to the axis of the mandrel body; the threaded rod is arranged on the first mandrel polished rod; the flat nut is matched with the threaded rod; the left end face of the mandrel body is provided with a left end center hole, and the right end face of the mandrel body is provided with a right end center hole. By adopting the positioning mandrel, all the outer surfaces of the bearing bush are subjected to grinding through one-time positioning and clamping, and the coaxiality of all outer circles is guaranteed; the positioning mandrel facilitates clamping, repeated alignment is not needed in other procedures after alignment is conducted once; the positioning mandrel is applicable to coupling bearing bushes with different lengths and wide in machining range.