How its made---Elbow Two

How its made----Elbow two

1.Cold push forming

Cold push forming is a kind of elbow forming method which uses the tunnel forming principle to push the tube blank into the bending cavity of the die under the action of the hydraulic press. Cold push forming can be divided into cold push forming with mandrel and cold push forming without mandrel.

The advantages of cold push forming are simple process, no preheating of tube blank, one-time cold bending forming, small thinning rate of outer wall thickness, good quality of finished product, small local deformation, simple die structure, easy operation, fast forming speed and low production cost, so it is suitable for mass production.

The common defects of cold pushing elbow are thinning of outer arc, thickening of inner arc, wrinkling, fracture, surface scratch, etc. This is because in the process of cold pushing elbow, the outer arc of elbow is lengthened due to tangential tension, and the inner arc is shortened due to tangential compression.

The main pressure f makes the upper die move downward, the upper die and the lower die close the die, the push rod pushes the tube blank to enter the die cavity through the guide section under the action of the force F, and the tube blank is formed into an elbow under the action of the mandrel . In order to avoid the situation that it is not easy to demould the elbow after forming, it is usually necessary to add lubricant to the tube blank before forming to make demoulding easier .

Hot push forming

The hot push forming technology is to use the induction heating method to heat the tube blank to enhance the plasticity of the material, and then use the two-step hydraulic push bending to expand the diameter under the action of the mandrel inside the tube blank to form an elbow with a larger diameter than the tube blank. Hot push forming elbow is suitable for continuous production with fast production rate and can produce different specifications of elbow. It is a low production cost forming method in the existing elbow forming methods, so it is widely used in the elbow production. However, when forming carbon steel elbow, there is a high red hardness requirement for the internal angle mandrel, and the heating temperature of elbow during forming needs to be controlled between 750 ℃ ~ 950 ℃

The elbows produced by the hot push process are beautiful in appearance, good in forming quality and even in wall thickness, and are very suitable for continuous mass production. Therefore, the hot push process is usually used in the forming of alloy steel, stainless steel and carbon steel elbows.

It is very important to use what kind of heating method when the elbow is formed by the hot push forming method

There are three heating modes: induction heating, reverberatory furnace heating and flame heating. In the actual production, a suitable heating method is usually selected according to the product demand and the actual situation of the factory.

 stamping

The so-called stamping forming is a method that the tube blank with inner core is directly pressed by die to form elbow. In the initial production of seamless elbow, the stamping method realizes the mass production of elbow, and is widely used in the elbow production. The stamping method has some disadvantages, that is, the forming quality of the elbow formed by stamping is not good, the wall thickness deviation of the elbow is large and the appearance of the elbow formed is not beautiful, and the mold cost is also very high when forming large-scale elbow. Therefore, in today's elbow production, stamping has been gradually replaced by other forming methods. But in the production of some special elbows, stamping is still used.

When the elbow is produced by stamping, it is necessary to determine whether to make cold stamping or hot stamping according to the actual production needs and the tonnage of production equipment.

Other forming methods

Extrusion method: the method of forming elbow by extrusion of upper and lower dies. The elbow formed by this method has good quality and beautiful appearance, which is usually used in manufacturing some thin-walled elbows. However, the extrusion method requires a very high precision of the upper and lower dies, and the required deviation of the wall thickness is also very small.

Contact: Mr.Dong                             Email: [email protected]

Web: www.limingbending.com                   Mobile:0086 13931703233