Elbow is used for pipeline turning of a stainless steel pipe fittings, with a 90 degree elbow and 45 degree elbow. elbow production manufacturing process have the hot pushing elbow, stamping elbow, extrusion elbow, butt welding elbow of these methods.
First, the hot pushing pipe elbow is seamless elbow manufacturing use a kind of craft, the Elbow push processing machine core mold and a heating device, using sets in the mold of billet in the Elbow push system promote to run in front, in the running of the pipe for heating and expanding diameter and bending forming process. The deformation characteristics of the hot pushing elbow is based on the metal plastic deformation before and after constant volume law to determine the tube diameter, the tube diameter less than the diameter of the elbow, the through mandrel control the blank deformation process, the arc by the compression of the metal flow, compensation for expanding and other parts of the thin, in order to get uniform wall thickness of elbow. The hot pushing elbow forming process has the advantages of beautiful appearance, uniform thickness and continuous operation, suitable for mass production. Therefore, it becomes the main processing method of carbon steel, alloy steel elbow, and is also used in some specifications of stainless steel elbow forming.
Second, stamping pipe elbow is first used in mass production, the forming process of seamless elbow, currently in the production of the elbow of the commonly used specifications has been hot pushing pipe method or other forming techniques of alternative, but in some specifications of elbow due to less number of production, wall thickness too thick or too thin, products are special requirements are using stamping manufacturing process. The bending of the elbow is equal to the diameter of the elbow, which is directly pressed and shaped by the press. Before stamping, the tube is placed in the lower mold, the inner core and the end of the tube into the tube blank, the upper mold is pressed down, and the elbow is formed by the external and internal model. Compared with the hot pushing process, forming the appearance quality is inferior to the former, stamping elbow in the forming of outer arc in tension and other parts of excess metal is not the compensation, so outside the arc wall thickness reduction thin about 10%. However, due to the characteristics of single piece production and low cost, it is suitable for the manufacture of small batch and thick wall elbow.
Third, Use a dedicated bend forming machine to squeeze the pipe elbow, the pipe into the mold, the push of the push rod, tube blank along the inner mold and the outer mold to complete the clearance movement and the completion of the forming process. The shape of elbow is beautiful, the wall thickness is uniform and the size deviation is small, so the cold extrusion production process is suitable for the manufacture of thin wall stainless steel elbow.
Fouth, butt welding pipe elbow production manufacturing process of large diameter elbow butt welding production process is used, the plate in the shape of rolled into the elbow, and then welding, after welding, then to the elbow film in, large diameter elbow. In general, the butt welding elbow, elbow butt welding appearance than other manufacturing processes is beautiful, but other processes of DN800 above the elbow production can not manufacture, the production process of butt welding pipe elbow.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)