An Investigation into the Comparison between Hot and Cold Forming of Copper-Aluminum Composite Tubes by utilizing Hydroforming and Gasforming Processes

Nowadays the formability of multi-layered tubes through different kinds of forming processes has been of interest to researchers due to its vast applications in aerospace, oil and petrochemical industries. This study compares cold forming and hot forming of bi-layered composite tubes via hydroforming and gas blow forming the tubes in geometrical model of a closed die bulge. The effect of these forming processes operational conditions on the bi-layered copper (inside) – aluminum (outside) tubes forming, wrinkling, bursting, buckling and the thickness distribution controlling on the die profile region in various situations were investigated. Hydroforming process was executed at ambient temperature with the maximum pressure of 300 bar. The process of blow gas forming at 550 ° C temperature and 40 bar pressure was implemented. The expansion ratio of the bi-layered tube during the gas blow forming process exceeded 1.35 % in comparison that of hydroforming process. In addition, the die experienced burst before the fitting during the gas blow forming process. The undamaged closed die bulge was formed through 280 bar hydroforming process with the conditions of 6 mm linear loading and 1.65 mm maximum thinning.