Seamless steel elbow: steel elbow is a kind of pipe fitting used in the turning of pipelines. 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. The commonly used seamless bending steel head forming processes in the manufacturing plant include hot pushing, stamping, extrusion, and so on. The hot pushing steel elbow-forming process is to use a special elbow-pushing machine, core mold, and heating device so that the billet set on the mold moves forward under the push of the pushing machine and is heated, expanded, and The process of bending and forming. The deformation characteristics of the hot push steel elbow are to determine the diameter of the tube blank according to the law that the volume of the metal material remains unchanged before and after plastic deformation. The diameter of the tube blank used is smaller than the diameter of the steel elbow. The metal flow compressed at the arc is compensated by other parts that are thinned due to diameter expansion, to obtain a steel elbow with uniform wall thickness.
The hot push steel elbow forming process has the characteristics of a beautiful appearance, uniform wall thickness, and continuous operation, and is suitable for mass production. Therefore, it has become the main forming method of carbon steel and alloy steel elbows and is also used in certain specifications of stainless steel. The elbow is being formed.
The heating methods in the forming process include medium-frequency or high-frequency induction heating (the heating ring can be multi-circle or single-circle), flame heating, and reverberatory furnace heating. The heating method depends on the requirements of the formed product and the energy situation. Stamping forming steel elbow is the earliest forming process used in the mass production of seamless steel elbow. It has been replaced by the hot push method or other forming processes in the production of steel elbows of common specifications, but in some specifications In the steel elbow, due to the small production quantity, the wall thickness is too thick or too thin.
It is still used when the product has special requirements. The stamping forming of the steel elbow adopts a tube blank with the same outer diameter as the steel elbow, which is directly pressed and formed in the mold by a press.
Before stamping, the tube blank is placed on the lower die, the inner core and end die are put into the tube blank, the upper die moves downward to start pressing, and the steel elbow is formed through the constraint 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 stamped 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 reduced by about 10. %about. However, due to the characteristics of being suitable for single-piece production and low cost, the stamping steel elbow process is mostly used in the manufacture of small batches and thick-walled steel elbows.
Stamped 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 cold extruded steel elbow is to use a special elbow forming machine to put the tube blank into the outer mold. The remaining gap moves to complete the forming process.
The steel elbow manufactured by the cold extrusion process of the inner and outer molds has a beautiful appearance, uniform wall thickness, and small dimensional deviation. Therefore, this process is often used for the forming of stainless steel elbows, especially thin-walled stainless steel elbows. The precision requirements of the inner and outer dies used in this process are high; the requirements for the wall thickness deviation of the tube blank are also relatively strict.
Middle plate welding: Use the middle plate to make half of the steel elbow section with a press, and then weld the two sections together. This process is generally used to make steel elbows above DN700. In addition to the above three commonly used forming processes, the forming of seamless steel elbows also uses a forming process in which the tube blank is extruded to the outer mold, and then the tube blank is passed through the ball to shape it. However, this process is relatively complicated, and cumbersome to operate, and the forming quality is not as good as the aforementioned process, so it is rarely used
Post time: May-26-2023