Crosses can be divided into equal-diameter and reduced-diameter, and the nozzle ends of equal-diameter crosses are of the same size; The main pipe size of the reducing cross is the same, while the branch pipe size is smaller than the main pipe size. The stainless steel cross is a kind of pipe fitting used at the pipe branch. For the manufacturing of the cross with seamless pipe, there are currently two commonly used processes: hydraulic bulging and hot pressing.
A. Hydraulic bulging of hydraulic bulging cross is a forming process of expanding branch pipe through axial compensation of metal material. The process is to use a special hydraulic press to inject liquid into the pipe blank with the same diameter as the cross, and extrude the pipe blank through the synchronous centering movement of the two horizontal side cylinders of the hydraulic press. The volume of the pipe blank becomes smaller after being squeezed, and the pressure of the liquid in the pipe blank increases with the volume of the pipe blank becoming smaller. When the pressure required for the expansion of the cross branch pipe is reached, Under the double action of liquid pressure in the side cylinder and tube blank, the metal material flows along the inner cavity of the mold and expands out of the branch pipe. The hydraulic bulging process of the cross can be formed at one time, with high production efficiency; The wall thickness of the main pipe and shoulder of the cross increased. Due to the large tonnage of equipment required for the hydraulic bulging process of seamless cross, at present, it is mainly used for the manufacturing of standard wall thickness cross less than DN400 in China. The applicable forming materials are low carbon steel, low alloy steel and stainless steel with relatively low cold work hardening tendency, including some non-ferrous metal materials, such as copper, aluminum, titanium, etc.
B. Hot pressing forming of cross is to flatten the pipe blank larger than the diameter of the cross by about the diameter of the cross, and open a hole at the part where the branch pipe is stretched; The tube blank is heated and put into the forming die, and the die for drawing the branch pipe is put into the tube blank; Under the action of pressure, the tube blank is compressed radially. During the process of radial compression, the metal flows towards the branch pipe and forms the branch pipe under the drawing of the die. The whole process is formed through the radial compression of the tube blank and the stretching process of the branch pipe. Unlike the hydraulic bulging spool, the metal of the hot-pressed spool is compensated by the radial motion of the pipe blank, so it is also called the radial compensation process. The tonnage of equipment required for material forming is reduced due to the heating and pressing of cross. Hot-pressed cross has wide adaptability to materials, and is applicable to materials of low carbon steel, alloy steel and stainless steel; Especially for the cross with large diameter and thick pipe wall, this forming process is usually adopted.
Post time: Mar-07-2023
