The mold used for stretching is called a stretching die, which is a tool for mass processing materials (metal or non-metal) into required stampings. According to the type of assembly, stretching dies can be divided into single-stroke deep-drawing dies, compound dies, and progressive deep-drawing dies. They can also be categorized by stamping machinery as single-action press stretching dies, double-action press stretching dies, and triple-action press stretching dies, with the main distinguishing factor being the difference in the edge holding device (elastic or rigid edge holding). Stretching dies can also be classified into first-stage deep-drawing dies and subsequent process deep-drawing dies, with the main difference lying in the structure and positioning of the edge holding rings.