Reduced Bends (Reducing Elbows) are pipe fittings used for varying pipe diameters. The commonly used forming processes include reducing extrusion, expanding extrusion, or a combination of both. For certain sizes of reducing elbows, stamping forming can also be employed.

a. Coning/Extrusion Shaping

The reduction forming process for male and female ends involves placing a billet with a diameter equal to the male end of the pipe into a forming die, then pressing it along the axial direction of the billet to cause the metal to move and contract within the die cavity. Depending on the size of the diameter change in the eccentric pipe, it is classified into single-stage or multi-stage forming.

b. Stamp forming

In addition to using steel pipes as raw materials for manufacturing elbows, steel plates can be utilized for certain specifications, and formed through stamping processes. The shape of the stamping die used for stretching is designed based on the inner surface dimensions of the elbows, and the steel plate, after being cut to size, is stamped and stretched into the desired shape.