关键词: 汽车桥壳, 液压胀形, 初始胀形内压, 经向应力比, 预胀形管坯

Abstract:

The  hydroforming technology of light axle housing was introduced.The formula of initial internal pressure was  deduced,and the influences of the relation of the internal pressure and axial thrust (axial stress ratio)in the pre-bulging process  on  the deformation sequence was predicted. The hydroforming experiments were done on general hydraulic machine under two different  load  paths.Under the first load path,the initial axial stress  ratio  was negative and the pressure  was constant throughout  the  feeding process,the pre-bulging tube was first deformed to a double-drum type with the diameter of two sides larger than the central, and the central part was finally bulged by increasing the internal pressure. Under the second load path,the initial axial stress ratio was positive and the pressure  was  constant throughout the feeding process, the central of the tube cracked axially. The common concave defects  of the samples of two load paths were observed at the transition region between flat cone and bulging area, and it will not disappear after the final bulging.Both of the theoretical analyses  and experiments  demonstrate that the initial deformation conditions have an important influence on the pre-bulging process of light axle housing.

Key words: automobile axle housing;hydroforming;initial pressure;axial , stress ratio;pre-bulging , tube