Turning-over auxiliary device for steel box girder welding

The invention discloses a turnover auxiliary device for steel box girder welding, which comprises a turnover frame, and a movable steel plate is movably hinged to the bottom of one side of the turnover frame. By arranging the turnover frame, the hoisting holes, the movable steel plates and the connecting bolts, two bridge cranes between the two bridge cranes are prepared to be matched for use according to the weight of a beam section during turnover, one bridge crane hoists the turnover frame through the hoisting hole in the highest position of the turnover frame, and the other bridge crane hoists the hoisting hole in the side face of the other turnover frame; after the two bridge cranes lift the box girder off the ground, 90-degree overturning can be carried out through cooperation, after overturning is completed, the box girder falls to the ground, the position of the lifting hole is adjusted, 90-degree overturning is carried out again, and then 180-degree overturning of the top face and the bottom face of