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. When categorized by the stamping equipment, they can also be classified 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 blank holder device (elastic blank holding and rigid blank holding). Stretching dies can also be categorized into initial deep drawing dies and subsequent process deep drawing dies, with the main difference lying in the structure and positioning method of the blank holder rings.