Forming of stainless steel elbow

　　Stamping bending is the first forming process for mass production of stainless steel elbow. At present, it has been replaced by hot push or other forming processes in the production of common specifications, but the production quantity is less, the thickness of the wall is too thick or too thin in some specifications.

　　Stamping: the product is still in use when it has special requirements. The stamping process of stainless steel elbow is made of tube blank equal to the stainless steel elbow diameter, and the press is directly pressed in the mould by pressing machine. Before stamping, the tube blank is placed on the lower die, the inner core and the end die are loaded into the tube billet, and the upper die starts to press down, and the stainless steel elbow is formed by the constraint of the outer die and the support of the internal mold. When the stainless steel elbow is formed, the outer arc is stretched, no other parts of the metal are compensated, so the wall thickness of the outer arc is reduced by about 10%. However, due to the characteristics of single piece production and low cost, the stamping stainless steel elbow technology is mostly used for the manufacture of small batch and thick wall ASTM A234 Wp11 Stainless Steel Elbow.

　　Stamping stainless steel elbow is divided into two parts: cold stamping and hot stamping. Cold stamping or hot stamping is usually selected according to material properties and equipment capabilities. The forming process of the cold extrusion stainless steel elbow is to use a special elbow forming machine and put the tube into the outer die. After the upper and lower die closing, the forming process is completed by the clearance movement of the inner and outer dies under the push of the push rod. The bending head made with internal and external die cold extrusion process has beautiful shape, uniform wall thickness and small size deviation, so the stainless steel elbow, especially the thin-walled stainless steel elbow, is made by this process. This process requires high accuracy of internal and external mold, and very strict requirements for the wall of the tube blank.