The process flow of the steel elbow

Seamless Steel Elbow: Steel Elbow is a type of pipe fitting used in pipe bends. Among all the pipe fittings used in the piping system, the proportion is about 80%. Usually, different forming processes are selected for steel elbows of different materials or wall thicknesses. Commonly used seamless steel elbow forming processes in manufacturers include hot pushing, stamping, extrusion, etc. The hot push steel elbow forming process uses a special steel elbow push machine, a core mold, and a heating device, so that the blank set on the mold moves forward under the push of the push machine, and is heated, expanded, and bent during the movement. the process of. The deformation characteristic of the hot push steel elbow is to determine the diameter of the tube blank according to the law that the volume of the metal material does not change before and after plastic deformation. The diameter of the tube blank used is smaller than the diameter of the steel elbow. The metal flow is compensated to other parts thinned by the expansion, to obtain a steel elbow with a uniform wall thickness.

The hot push steel elbow forming process has the characteristics of beautiful appearance, uniform wall thickness, and continuous operation, and is suitable for mass production, so it has become the main forming method of carbon steel and alloy steel elbows and is also used in certain specifications of stainless steel elbows. is taking shape. The heating methods in the forming process include medium frequency or high-frequency induction heating (the heating coil can be multi-turn or single-turn), flame heating, and reverberatory furnace heating. The heating method used depends on the requirements of the formed product and energy conditions. Stamping and forming steel elbow is the earliest forming process applied to the mass production of seamless steel elbows. It has been replaced by the hot push method or other forming processes in the production of steel elbows of common specifications. Less, the wall thickness is too thick or too thin. The product is still in use when there are special requirements. The stamping forming of the steel elbow adopts the tube blank equal to the outer diameter of the steel elbow, which is directly pressed in the mold using a press. Before stamping, the tube blank is placed on the lower die, the inner core and end die are loaded into the tube blank, the upper die moves downward to start pressing, and the steel elbow is formed by the restraint of the outer die and the support of the inner die.

Compared with the hot push process, the appearance quality of stamping is not as good as the former; the outer arc of the stamping steel elbow is in a stretched state during forming, and there is no excess metal in other parts to compensate, so the wall thickness at the outer arc is about 10% thinner. . However, due to the characteristics of being suitable for single-piece production and low cost, the stamping steel elbow process is mostly used for the manufacture of small batches and thick-walled steel elbows. Stamping steel elbows are divided into cold stamping and hot stamping. Usually, cold stamping or hot stamping is selected according to material properties and equipment capabilities. The forming process of the cold extrusion steel elbow is to use a special steel elbow forming machine to put the tube blank into the outer die. Clearance movement to complete the forming process. The steel elbow manufactured by the internal and external die cold extrusion process has a beautiful appearance, uniform wall thickness, and small size deviation. Therefore, this process is mostly used for the forming of stainless steel elbows, especially thin-walled stainless steel elbows. The inner and outer molds used in this process have high precision requirements; the requirements for the wall thickness deviation of the tube blank are also relatively strict.

Welded plate. Use a medium plate to make half of the steel elbow section with a press, then weld the two sections together. This process is generally used for steel elbows above DN700. In addition to the above three commonly used forming processes, the seamless steel elbow forming also adopts the forming process of extruding the tube blank into the outer die and then shaping the tube blank through the ball. However, this process is relatively complex, troublesome to operate, and the forming quality is not as good as the previous process, so it is rarely used.