Forming method of steel automobile fender

The invention relates to a forming method of a steel automobile fender for automobile part heat machining. The method comprises the steps of preparing material, discharging material, forming machining, post-machining and the like; establishing a digital pre-machining model and removing large-variable-radius arc and setting process cutting seam of the fender while carrying out the material preparing and the material discharging process; manufacturing flanges according to the equal-part parts to be planed to replace the large-variable-radius arc after the large-variable-radius arc of the fenderis equally divided, flattening the fender, generating a two-dimensional graphic element, correcting a cutting contour, and generating a blank by discharging the material to cut the plate; during forming machining, the bending pre-forming, the correcting and the sectional welding are carried out; a arc knife is bent for many times, the flanges are corrected one by one, the flanges are welded on the fender on the outer cont