Optimization Of Loading Path For Hydroforming Of T-shaped Tube

Hydroforming is an advanced technology used to manufacture hollow lightweight part. Compared to stamping, tube hydroforming offers light weight, good rigidity, less components, less subsequent machining and assembly operations, etc. This technology has been widely used in the field of automobile, aviation and aerospace industry. Three-way tube formed by hydroforming technology has some other advantages, such as higher precision, tighter tolerance, higher reliability and smaller exhaust resistance as it can improve the gas flow characteristics in the tube. These advantages are the important guarantee for improving reliability and power of automobile, aircraft and rocket. In the process of tube hydroforming, the loading path is crucial to the quality of formed parts. Thus the design and optimization of loading path is an important issue for tube hydroforming.Optimization of loading path for T-shaped tube hydroforming was investigated through numerical simulation and experiments. An adaptive simulation software based fuzzy control algorithm was developed to optimize loading path for hydroforming of T-shaped tube. It includes six evaluation functions which are adopted for identifying geometrical shape and quality of T-shaped tube during the forming process simulation, 848 fuzzy control statements in the fuzzy controller summarized from expert experience is used to adjust forming parameters. Working together with LS-DYNA, the software can automatically design optimized loading path instead of traditional trail-and-error FEA approach. In this way, design time for reasonable loading path is greatly shortened.In this paper, the software was used to optimize the loading path for hydroforming process of stainless steel tube with 103mm diameter, in which different initial position of the middle punch was used. T-shaped tubes are successfully formed by using these optimized loading paths. Numerical simulation and experimental results show that the thickness distribution of formed part is affected by different initial position of the middle punch. In addition, the software was also used to optimize the loading paths respectively for hydroforming of stainless steel reducing T-shaped tube with 86mm diameter and aluminum reducing T-shaped tube with 145mm diameter. Reliability, adaptability and versatility of the software were demonstrated by numerical simulation and experiment.In this paper, a new T-shaped tube hydroforming process with elastic middle punch is studied. The forming process is divided into two steps. With the same feed loading path, experimental results show that, in the first step, the thickness of the tube formed by new process is thicker than that by traditional process, but thinner in the second step.