Development of Warm and Cold Tube Forming of Ti-6Al-4V Alloy by Press Forming

The low ductility of Ti–6Al–4V alloy at forming temperatures below 780 ℃ is still a problem. Ti–6Al–4V is usually hot press formed at 780 to 900 ℃. Hence, it is necessary to develop a new press forming for Ti–6Al–4V alloy sheets at forming temperatures below 780 ℃ to improve productivity. We developed a method to achieve of warm and cold press forming of Ti–6Al–4V alloy sheets by combining press motion control and clearance between a die and a blank. In this study, we tried tube forming by developed press forming method. In this method, the following two processes were separated: punch motion process without BHF and BHF motion process without punch motion. These two processes were carried out alternately during deep drawing or drawing and ironing. Three forming parameters, namely, the punch speed Spi, punch stroke Psi, and blank holding force BHFi, were controlled separately and the effect of forming conditions on deformation behavior was investigated by using experiment and finite element analysis (FEA). As a result, warm and cold tube forming of Ti–6Al–4V alloy was achieved without any undesirable deformation by applying the developed press forming method.