The size head is a kind of pipe fitting for reducing the diameter of pipe. Usually the forming process for reducing, expanding or reducing and expanding, for some specifications of the size of the head can also be used stamping forming. The size of the head is characterized by significantly higher strength than carbon steel with the same carbon content, good toughness and plasticity, good weldability and corrosion resistance, etc. The shrinking forming process of the large and small heads is to put the tube blank with the same diameter as the large and small heads into the forming die, and make the metal move along the die cavity and shrink to form by pressing along the axial direction of the tube blank. According to the size of the diameter of the head, it can be divided into one pressing forming or multiple pressing forming. Expanding forming is formed by expanding along the inner diameter of the tube billet which is smaller than the diameter of the large end of the reducing tube with an inner die. The process of expanding diameter mainly solves the problem that it is difficult to form the large and small head through reducing diameter. Sometimes, the methods of expanding and reducing diameter are combined according to the requirements of material and product forming. In the process of reducing or expanding deformation pressing, according to different materials and reducing diameter, it is determined to use cold pressing or hot pressing. As far as possible to use cold pressure, but for multiple diameters caused by severe work hardening, thick wall thickness or alloy steel material should be used hot pressure. In addition to using steel pipe as raw material to produce reducing pipe, some specifications of reducing pipe can also be produced by stamping forming process with steel plate.