Due to the large equipment required for the hydraulic expansion process of tee, the current market in China is mainly made of tee with standard wall thickness less than dn400. The suitable forming materials for this process are mainly low alloy steel, stainless steel and low carbon steel with low degree of cold work hardening, and some non-ferrous metals, such as aluminum and titanium, can also be used. The hot pressing forming of tee is mainly to flatten the tube embryo with relatively large diameter to the size of tee diameter, and at the same time, open a hole in the part of the drawing branch pipe; put the tube embryo into the tube Before the forming die is heated, a die for drawing branch pipe is installed in the tube blank; the tube blank is compressed radially under the action of pressure, at the same time, the metal in the tube blank flows to the direction of the branch pipe in this process, and finally the branch pipe is formed under the action of drawing of the die.
The whole forming process is realized by radial compression of tube embryo and stretching of branch pipe. Compared with the hydraulic expansion tee, the metal of the hot pressed tee is realized by the radial movement of the tube embryo. So we call this process radial compensation process. Because the heated tube embryo will restrict the tee, the required tonnage should be reduced in the process of material forming. For the practicality of materials, hot pressing tee is relatively wide, which is more suitable for alloy steel, stainless steel and other materials; especially for tee with larger diameter and thicker pipe wall, this process is often used.
The hydraulic expansion forming process of tee is a forming process of expanding branch pipe through the axial compensation of metal materials. This process must use a special hydraulic press to inject liquid into the tube embryo with the same diameter as the tee, and use the hydraulic press to squeeze the two horizontal side cylinders synchronously. When the tube embryo is under certain pressure, the overall volume becomes smaller. Due to the change of volume, the tube becomes smaller The liquid in the embryo will change with the volume of tube embryo, and the pressure will increase gradually. Once the pressure required for expansion of the tee branch pipe is reached, the metal material inside will expand out of the branch pipe under the liquid pressure in the tube embryo and the liquid pressure in the side cylinder.
Because of the particularity of the process, it is widely used in many industries.