Method and apparatus for hydroforming metallic tube

摘要

A method and apparatus for hydroforming a metallic tube (1) including the steps of: preliminarily expanding the metallic tube (1) over an axial section (W0) longer than the length of the expanded portion (W1) of a final product as measured in the axial direction of the metallic tube (1); and compressing the preliminarily expanded portion (W0) in the axial direction of the metallic tube so as to form the shape of the expanded portion (W1) of the final product. According to the method and apparatus of the invention, frictional resistance between the metallic tube (1) and processing tools can be reduced, and moreover, the internal pressure within the metallic tube (1) can be reduced during expansion processing. Furthermore, the cost for the manufacture of metallic die is reduced, and in addition, yield is improved.