Do you really know how the elbow works?

The role of elbow:

In the piping system, the elbow is to change the direction of the pipe fittings. According to the angle, there are 45 ° and 90 ° 180 ° three most commonly used, in addition, according to engineering needs also include 60 ° and another non-normal angle elbow. Elbow materials are cast iron, stainless steel, alloy steel, malleable iron, carbon steel, non-ferrous metals, and plastics.

Connected to the pipe are direct welding (the most common way) flange connection, hot fusion connection, electrofusion connection, threaded connection, and socket connection. The production process can be divided into welding elbow, stamping elbow, pushing elbow, casting elbow, butt welding elbow, etc. Other names: 90-degree elbow, right angle bend, etc.

 

Elbow Introduction.

Elbow is a common connection pipe fitting used in plumbing installation, for the connection of the pipe bend, used to change the direction of the pipe.

Other names: 90 ° elbow, right angle bend, love and bend, stamping elbow, pressed elbow, mechanism elbow, welded elbow, etc.

Use: Connect two nominal diameters of the same or different pipes, so that the pipeline for 90 °, 45 °, 180 °, and various degrees of the turn.

A bending radius less than or equal to 1.5 times the diameter of the pipe belongs to the elbow, and more than 1.5 times the diameter of the pipe belongs to the elbow.

 

Pipeline installation of a common connection with pipe fittings, connecting two nominal diameters of the same or different pipe, so that the pipeline to do a certain angle turn, nominal pressure of 1-1.6Mpa.

 

Elbow process.

① Seamless elbow:

Elbow is a pipe fitting used for pipe bends. Of all the pipe fittings used in the pipeline system, the largest proportion is about 80%. Usually, choose different forming processes for elbows of different materials or wall thickness. Manufacturing plants commonly used seamless elbow forming process are hot push, stamping, extrusion, etc.

② hot push forming

The hot push elbow forming process is the use of a special elbow pushing machine, core mold, and heating device so that the set of billet on the mold in the pushing machine moves forward, in the movement is heated, expanded, and bent into the process. The deformation characteristics of the hot push elbow are based on the law of plastic deformation of metal materials before and after the volume of the bullet diameter, the diameter of the billet used is less than the diameter of the elbow, through the core mold to control the deformation process of the billet, so that the inner arc of the compressed metal flow to compensate for the expansion and thinning of other parts, so as to obtain a uniform wall thickness elbow.

The hot push elbow forming process has a beautiful appearance, uniform wall thickness, and continuous operation, suitable for mass production, thus becoming the main forming method of carbon steel, alloy steel elbow, and also applied in the forming of certain specifications of stainless steel elbow.

Forming process heating methods are medium frequency or high-frequency induction heating (heating circle can be multi-turn or single turn), flame heating, and reflection furnace heating, the use of which heating method depending on the requirements of the forming product and the energy situation.

③ Stamping forming

Stamping forming elbow is the earliest used in the mass production of seamless elbow forming process, in the production of commonly used specifications elbow has been replaced by hot push method or another forming process, but in some specifications of the elbow due to the production of small quantities, wall thickness too thick or too thin.

The product is still in use when there are special requirements. Elbow stamping and forming using a billet equal to the outside diameter of the elbow, using a press in the mold directly pressed into shape.

Before stamping, the billet is placed on the lower die, the inner core and end die are loaded into the billet, the upper die moves down to start pressing, and the elbow is formed by the constraint of the outer die and the support of the inner die.

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 in a tensile state, no other parts of the excess metal to compensate, so the wall thickness of the outer arc is about 10% thinner. But because of the characteristics of single-piece production and low cost, so the stamping elbow process is mostly used in small quantities, thick-walled elbow manufacturing.

The stamped 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.

The cold extrusion elbow forming process is the use of a special elbow forming machine, the billet into the outer die, the upper and lower die after they die, under the push rod, and the billet along the inner and outer die reserved for the gap movement and complete the forming process.

The use of cold extrusion process inside and outside the die manufacturing elbow beautiful appearance, uniform wall thickness, small size deviation, so for stainless steel elbow, especially the thin-walled stainless steel elbow forming more than the use of this process manufacturing. This process requires high accuracy of the internal and external die; the wall thickness deviation requirements of the billet are also relatively harsh.

 

Elbow range of application.

Because the elbow has a good overall performance, it is widely used in chemical, construction, water supply, drainage, petroleum, light and heavy industry, refrigeration, sanitation, plumbing, fire, electric power, aerospace, shipbuilding and another basic engineering.

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