Experimental and numerical analysis of titanium microtube elliptical flaring

Traditional tube flaring processes focuses on expanding one end of the tube without changing its cross-sectional shape. This paper presents a new two-step tube flaring process for expanding one end of a titanium alloy microtube while simultaneously changing its cross-sectional shape from circular to elliptical. Experiments were performed to investigate and verify this process. Furthermore, an analytical model was developed to analyze the forming process and investigate the relationship between punch feed and maximum plastic strain during the flaring process. The analysis shows that the two-step flaring process used is effective in expanding the circular cross section to an elliptical cross section without failure. It is also shown that the developed analytical model can predict the fracture of the tube end during the flaring process approximately. Finally, a FEM simulation was performed to further investigate the two-step flaring process.