Irregular-section tubular body and axle beam for torsion beam and method of manufacturing the same

摘要

The invention provides a method of manufacturing an irregular section tubular body and axle beam. The axle beam has a tubular worked body that has sealed liquid therein and is press-formed by upper and lower press molds. One of the press molds has a convex mold portion to form a concave portion concaved in an axis perpendicular direction at an axial part of the axle beam. The press-forming of the tubular worked body is completed by a one stroke process using liquid pressure that increases as the internal volume of the worked body decreases due to formation of the concave portion. The concave portion extends substantially the length of the axle beam and has a substantially U-shaped or V-shaped cross-section forming a closed and sealed space.