فهرست نشریات علمی دسترسی آزاد ایران

Given the widespread applications of tubes in the aerospace, automotive, and shipbuilding industries, incremental forming of thin-walled tubes has emerged as a novel and promising process for tube forming. However, incremental forming of tubes with high strength-to-weight ratios, such as titanium alloys, at room temperature is subject to significant limitations. In this study, an electric high temperature incremental forming (EHTIF) process has been developed for flanging the ends of thin-walled titanium tubes. To this end, a transformer was employed as the electric current source alongside incremental forming equipment comprising a CNC machine, dies, and forming tool. During the incremental forming process, the transformer supplies a high current intensity at low voltage between the forming tool and the workpiece, resulting in localized heating and an increase in the workpiece temperature. An experimental study was carried out to evaluate the formability of titanium tubes in the developed process, along with an investigation of the factors affecting it. The results demonstrated that the proposed EHTIF process significantly enhances the formability of titanium tubes compared to conventional cold incremental forming. Specifically, while cold incremental forming can achieve complete flange formation up to a height of 15 mm at a 90° angle, the EHTIF process allows for flange heights up to 30 mm. Furthermore, it was found that the application of solid lubricants, including heat-resistant grease, copper-based anti-seize, and graphite-based anti-seize, is crucial in preventing process defects such as poor surface quality and flange thinning. This approach not only improves the surface finish of the tubes but also reduces flange thinning.