Seamless pipe stainless steel tubing –weld elbow :Elbow is a kind of pipe fittings used in pipeline turns. In the piping system used in all the pipe fittings, the largest proportion, about 80%. Usually, different forming processes are selected for elbows of different materials or wall thicknesses. Seamless elbow forming process commonly used in manufacturing plants are hot push, stamping, extrusion and so on.
Hot push molding
Hot push elbow forming process is the use of special elbow pushing machine, mandrel and heating device, so that the set of billet on the mold in the pushing machine pushed forward in the movement is heated, expanding and bending forming process. The deformation characteristics of the hot push elbow is based on the law of plastic deformationof metal materials before and after the volume is unchanged to determine the diameter of the billet, the diameter of the billet used is smaller than the diameter of the elbow, through the mandrel to control the billet's deformation process, so that the inner arc of the compressed metal flow, to compensate for the thinning due to the expansion of the other parts of the elbow, so as to get a uniform wall thickness of the elbow.
Hot push elbow forming process has a beautiful appearance, uniform wall thickness and continuous operation, suitable for mass production characteristics, and thus become the stainless steel crimp fittings,stainless steel threaded pipe fittings of the main forming method, and also used in some specifications of the stainless steel elbow forming.
Forming process heating methods are medium-frequency or high-frequency induction heating (heating circle can be multi-turn or single-turn), flame heating and reflective furnace heating, the type of heating depending on the requirements of the molded product and the energy situation to decide.
Stamping and forming
Stamping forming elbow is the earliest application in the mass production of steel seamless tube -weld elbow
forming process, in the production of common specifications of the elbow has been replaced by the hot push method or other forming processes, but in some specifications of the elbow due to the production of a small number of wall thickness is too thick or too thin.
Products with special requirements are still in use. Stamping of elbow forming using a billet equal to the outer diameter of the elbow, the use of presses in the mold directly pressed into shape.
Before stamping, the billet is placed on the lower mold, the inner core and end mold into the billet, the upper mold downward movement to start pressing, through the outer mold constraints and the support of the inner mold to make the elbow forming.
Compared with the hot push process, the appearance of stamping forming quality is not as good as the former; stamping elbow in the forming of the outer arc is in the state of stretching, there is no other parts of the excess metal to compensate, so the outer arc of the wall thickness of about about 10% thinner. However, due to the application of single-piece production and low-cost features, so the stamping elbow process is used for small quantities, thick-walled elbow manufacturing.
Stamping elbow is divided into two kinds of cold stamping and hot stamping, usually according to the nature of the material and equipment capacity to choose cold stamping or hot stamping.
Cold extrusion elbow forming process is to use a special elbow forming machine, the billet into the outer mold, the upper and lower mold mold, in the push rod, the billet along the inner mold and the outer mold gap reserved for the completion of the forming process.
Cold extrusion process using internal and external mold elbow manufactured in a beautiful appearance, uniform wall thickness, small size deviation, so the stainless steel elbow, especially thin-walle stainless steel elbow
molding more than the use of this process. The internal and external mold used in this process requires high precision; wall thickness deviation requirements for the billet is also relatively harsh.
Plate welding
Use the center pipe to plate weld with a press to make half of the elbow profile, and then weld the two profiles together. This process is generally used for more than DN700 elbow.
Forge heat treating process
The use of forging machinery to exert pressure on the metal billet, so that it produces plastic deformation in order to obtain a certain mechanical properties, a certain shape and size of the forge heat treating process methods. Through the continuous pounding of the steel pipe fittings, so that the original segregation within the ingot, loose, porosity, slag and other compaction and welding, the organization becomes more compact, improving the plasticity and mechanical properties of the metal.l.
The main materials of forged pipe fittings are q235, q345, 16mn, 20#, 35#, 45#, 40Cr, 12Cr1MoV, 30CrMo, 15CrMo, 20G and so on. With forging fittings corresponding to the casting fittings, casting mechanical properties lower than the mechanical properties of the same material forgings, cast iron fittings will be melted into a metal to meet certain requirements of the liquid and poured into the casting, after cooling and solidification, finishing treatment to get a predetermined shape, size and performance of the casting (part or blank) process.
One of the forged elbow and 45 ° forged elbow, 90 ° forged elbow, forged socket weld elbow pressure level is divided into: 3000LB, 6000LB, 9000LB, socket weld elbow 3000LB suitable for the pipe wall thickness level of Sch80, XS; 6000LB suitable for the pipe wall thickness level of Sch60; 9000LB suitable for the pipe wall thickness level of XXS; stainless steel threaded pipe pressure level is divided into: 2000LB, 3000LB, 6000LB, threaded elbow 2000LB suitable for pipe wall thickness grade Sch80, XS; 3000LB suitable for pipe fittings wall thickness grade Sch60; 6000LB suitable for pipe fittings wall thickness grade XXS.
Post time: Sep-08-2023