Abstract
Dieless drawing technique, which can achieve a large reduction in the area of metal tubes in a single pass by local heating and cooling, is a flexible metal drawing process without dies. In this study, we suggested the effective drawing path control in the early drawing stage to restrain the unstable deformation, which leads to fracture. The actual deformation limit of the material is evaluated by coupled thermo-mechanical finite element analysis and experiments of the dieless drawing. The metal tubular materials used in the experiment are SUS304 alloy tubes of 2mm outer diameter. A high-frequency induction heating apparatus with a water-cooling box is used for the dieless drawing. Results show that effective drawing speed control enhances the forming limit in the dieless drawing. Moreover, the effect of heating length, which affects the temperature distribution, on the deformation behavior is investigated in the use of effective drawing speed control under the condition of avoiding the fracture by unstable deformation in the early drawing stage. It is found that the forming limit slightly improves with increasing heating length. Consequently, we clarified that it is possible to make the dieless drawing process successfully even if the local heating is not always realized.
