SPR self piercing riveting belongs to the cold connection method, and when used, the upper and lower layers of plates do not require pre-treatment and punching. The edge pressing ring pre presses the two layers of plates onto the bottom mold. Then punch the needle to press the rivet towards the sheet metal, and the rivet pierces into the sheet metal. The rivet penetrates the upper sheet metal and continues downwards, causing the sheet metal to flow towards the concave part of the bottom mold due to pressure. The hollow part of the rivet expands outward during the downward process due to the filling of the piercing plate and the protrusion of the concave part of the bottom mold. Until the lower surface of the punching needle is flush with the upper surface of the upper plate, the riveting is completed, and the rivet forms a "several" ("π") shaped rivet lock with the plate.