Special-shaped steel pipes are economic section steel pipes. Including non-circular cross-sectio最终轮廓、壁厚均匀、变量墙thickness, variable diameter and variable wall thickness along the length, symmetrical and asymmetrical cross-section, etc. Such as square, rectangle, cone, trapezoid, spiral, etc. Special-shaped steel pipes can better adapt to the particularity of use conditions, save metal and improve the labor productivity of parts manufacturing. It is widely used in aviation, automobiles, shipbuilding, mining machinery, agricultural machinery, construction, textiles and boiler manufacturing. The methods of producing special-shaped tubes include cold drawing, electric welding, extrusion, hot rolling, etc. The cold drawing method has been widely used.