The mold used for stretching is called a stretching die, which is a tool for mass-processing materials (metal or non-metal) into the required stampings. According to the type of assembly, stretching dies can be categorized into single-stroke deep drawing dies, compound dies, and progressive deep drawing dies. When differentiated by stamping equipment, they can also be classified into 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 edge holding and rigid edge holding). Stretching dies can also be divided into initial deep drawing dies and subsequent process deep drawing dies, with the primary difference lying in the structure and positioning of the edge holding rings.