Home  /  News

Do You Know The Process Of Making Elbows?

Jan. 09, 2020

In piping systems, elbows are fittings that change the direction of the piping. According to the angle, there are three most commonly used angles of 45 ° and 90 ° and 180 °. In addition, according to the needs of the project, it includes other abnormal angle elbows such as 60 °. Elbow materials are cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non-ferrous metals and plastics. Seamless steel pipe China supplier introduces you:

Seamless bend: Elbow is a kind of pipe fittings used for pipe turning. Of all the fittings used in the piping system, the largest proportion is about 80%. Generally, different forming processes are selected for elbows of different materials or wall thicknesses. The common elbow forming processes commonly used by manufacturers include hot pushing, stamping, and extrusion.

Hot push forming:

The hot push elbow forming process uses a special elbow pusher, core mold and heating device to make the blank set on the mold move forward under the push of the pusher, and it is heated, expanded and bent during the movement. the process of. The deformation characteristic of the hot push elbow is to determine the diameter of the tube blank according to the constant volume before and after the plastic deformation of the metal material. The diameter of the tube blank is smaller than the diameter of the elbow. The metal flow is compensated to other parts that are thinned due to the diameter expansion, so as to obtain an elbow with uniform wall thickness.

Hot push elbow forming process has the characteristics of beautiful appearance, uniform wall thickness and continuous operation, which is suitable for mass production. Therefore, it has become the main forming method of carbon steel and alloy steel elbow, and it is also applied to some specifications of stainless steel elbow Forming.

Seamless Elbow

Seamless Elbow

The heating methods in the forming process include intermediate frequency or high frequency induction heating (the heating ring can be multi-turn or single-turn), flame heating and reverberatory furnace heating. Which heating method is used depends on the requirements of the formed product and the energy situation.


The stamping elbow is the earliest forming process used for mass production of seamless elbow. It has been replaced by the hot push method or other forming processes in the production of commonly used elbows, but in some elbow specifications Due to the small production quantity, the wall thickness is too thick or too thin.

The product is still used when there are special requirements. The bending of the elbow uses a pipe blank with the same outer diameter as the elbow, and it is directly pressed into the mold using a press.

Before punching, the tube blank is placed on the lower mold, the inner core and the end mold are loaded into the tube blank, and the upper mold moves downward to start pressing. The elbow is formed by the restraint of the outer mold and the support of the inner mold.

Compared with the hot push process, the appearance quality of stamping is not as good as the former. When the stamping elbow is formed, the outer arc is stretched, and there is no excess metal in other parts to compensate, so the wall thickness at the outer arc is reduced by about 10%. . However, due to the characteristics of single-piece production and low cost, stamping elbow technology is mostly used in the manufacture of small batches and thick-walled elbows.