Crankshaft journal straightness correcting method

The invention relates to the technical field of crankshaft machining, in particular to a crankshaft journal straightness correcting method. The method mainly comprises the following steps of (1) finely grinding a crankshaft journal; (2) carrying out nitrogen treatment on the finely ground crankshaft journal; (3) mounting a supporting rolling post on a lower rolling head; (4) mounting the crankshaft journal between an upper rolling head and the lower rolling head, and clamping the crankshaft journal; (5) mounting a rolling wheel onto the upper rolling head; (6) starting a motor to drive a crankshaft to rotate, wherein the rolling wheel rolls the crankshaft journal, the supporting rolling post corrects a crankshaft journal rolling bump and comprises a cylindrical part positioned on the middle part and a rotary curve surface part positioned on the end part, and in a rolling process, the rotary curve surface part on the end part is in contact with a crankshaft journal rolling bump line. The method has the advantages that rolling bump caused by plastic deformation nearby a crankshaft journal fillet can be corrected, and the crankshaft journal straightness is corrected.