Generally, it can be divided into the following categories. The first type is one-to-one forming, which is divided into a middle mold and upper and lower punching; the second type is one-to-two forming, which is a middle mold, upper punching, lower outer punching, and lower inner punching; the third type is two-team two-forming, including Upper outward punching, upper inner punching, lower outer punching, lower inner punching, etc. There is another type which is relatively rare and can be formed by two to three. This type is more complicated. This pair has relatively high requirements on the machine. I hope it will be helpful to you. You are useful!