Process and die for forming self-flowing drill screw with specific tail shape

The invention discloses a forming process and a die for a self-flowing drill screw with a specific tail shape, and the process comprises the following steps: continuously finishing shearing and blanking, blank rounding and shaping, tail extrusion forming, head upsetting forming, and upsetting and extruding composite forming of a rod part triangular characteristic and a screw head characteristic on a multi-station cold forming die, namely extruding a fillet at one end of a blank; synchronously shaping the other end to obtain a flat section; a specific tail shape is formed through extrusion of an extrusion die with molded surface characteristics, and the other end is subjected to upsetting deformation to obtain a large bowl-shaped head step; upsetting-extruding composite forming is carried out through a die with a floating structure, and the triangular characteristic of the screw rod part and the flange shape, with the inner plum blossom sinking groove, of the screw head part are obtained; and then a rod thread