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Process flow of seamless elbow

times   2016-08-30

Seamless elbow: elbow is a kind of pipe fitting used for turning of pipe. In the pipeline system used in all the pipe fittings, the largest proportion, about 80%. In general, different forming processes are selected for different materials or wall thicknesses. At present, the factory used seamless elbow forming process, hot stamping, extrusion have.

Hot forming

The hot pushing elbow forming process is the use of special elbow producing machine, mould and heating device, the set of billet in the mold on the forward movement in the push machine under the process in motion is heated, expanding and forming. The deformation characteristics of the hot pushing elbow is based on the law of constant volume plastic metal materials before and after deformation to determine the tube diameter, tube diameter less than the diameter of the elbow, the deformation process of mould blank control, the metal flow in the arc compressed, compensation due to expanding and reducing other parts of thin, so get the uniform wall thickness of elbow.

Has a beautiful shape, uniform wall thickness and continuous operation of the forming process of the hot pushing elbow, is suitable for mass production, and thus become the main forming method of carbon steel, alloy steel elbow, forming and application in some specifications of stainless steel elbow.

The heating method of forming process has the intermediate frequency or high-frequency induction heating (the heating coil can be multi circle or single ring), the flame heating and the reflection furnace heating.

Stamping forming

Stamping elbow is first used in the forming process, batch production of seamless elbow at present, in the production of specifications used in elbow has been hot forming process or other alternatives, but in some specifications of the elbow due to the production quantity and the wall thickness too thick or too thin.

Products have special requirements are still in use. The stamping of the elbow is formed by using the tube blank equal to the outside diameter of the elbow.

Before stamping, the tube blank is placed on the lower die, and the inner core and the end mould are filled in the tube blank, and the upper die downward movement begins to press down.

Compared with the hot stamping process, the appearance quality is inferior to the former; stamping elbow when formed outside the arc in tension, no other metal parts of excess compensation, so the outer arc wall thickness thinning of about 10%. However, due to the characteristics of the single piece production and low cost, the stamping elbow process is used for the manufacture of small batch and thick wall elbow.

Stamping elbow points cold stamping and hot stamping two kinds, usually based on the properties of materials and equipment selection of cold stamping or hot stamping.

The cold extrusion forming process is the use of special elbow bend forming machine, tube into the outer mold, lower mold clamping, driven by the push rods, tubes reserved along the inner mold and the external mold of the clearance and finish forming process.

The elbow made by cold extrusion technology of internal and external mold is beautiful, uniform wall thickness and small size, so it is used for stainless steel elbow, especially for stainless steel elbow. The precision of internal and external die used in this process is high, and the requirement for the wall thickness deviation of tube blank is also very strict.

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Medium plate welding system

Half of the bend section is made by using the medium plate press, and then the two sections are welded together. This process is generally used for DN700 above the elbow.

Other forming

In addition to the above three kinds of forming process, and the seamless elbow forming tube extrusion die to the outside, and then through the forming process of tube in ball shaping. But this process is relatively complicated, and the operation is troublesome, and the forming quality is inferior to that of the preceding process, so it is less used.

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