The process of small cross-section profile pipe is very special for the reason of its structure (such as small cross-section, lots of holes, and different wall thickness).

A new type of construction mold in taking shape of unusual tube;

The processing technology of twinextrusion diehead for PVC profile shapes and pipes,namely the technology of one extruder extruding twin product at the same time,was introduced.

Hydro-forming's principal and technic processing are introduced and two kinds of the machine design approaches for different section tube are offered in this paper.