Girder machining method and girder machining device for crane and crane span collecting-mounting method

The invention relates to a girder machining method and a girder machining device for a crane and a crane span collecting-mounting method. The girder machining method for the crane comprises the following steps of step 1, welding girder hanging plates onto corresponding positions of two ends in the length direction of the girder, and enabling the side faces of the girder hanging plates to face the outside of the length direction of the girder; step 2, placing a girder bracket onto a corresponding girder support, fixing by a girder fixing device on the girder support, and utilizing corresponding machining equipment to machine a pressing plane used for being pushed and matched with corresponding matching faces on end beams; step 3, machining thread connecting holes penetrating through the girder hanging plates along the thickness direction in set positions of the girder hanging plates; finally, jointing the end beams with the girder and fixing the end beams and the girder by bolts. By adopting the technical scheme, the collecting-mounting quality of a crane span is prevented from being influenced by welding deformation.