Effect of Drawing Speed on Deformation Behavior in Dieless Drawing of Metal Microtubes
Dieless drawing is a flexible metal drawing technique without some conventional dies and mandrels. In dieless drawing, tubes are subjected to axial load and are going through heating area to cooling area, so that necking takes place at the heating area continuously. Dieless drawing limit is determined by difference in flow stresses between heating and cooling areas. Meanwhile, in dieless drawing, the strain rate affects flow stress written in σ = Kε~m ε~m at deformation area. Therefore, the strain rate is an important factor in the dieless drawing, especially, for micro-scale high speed drawing with superior dieless drawing limit. However it is not enough to clarify the effect of strain rate on deformation behavior for fabricating microtubes with high efficiency. In this study, the effect of strain rate on deformation behavior in high speed drawing is investigated to evaluate effectiveness of dieless drawing for fabrication of microtubes. Firstly, dieless drawing experiments are conducted for SUS304 stainless steel with various drawing speeds in micro scale. Outer diameter profile is measured to calculate mean strain rate in deformation area. The result shows that the mean strain rate increases with increasing drawing speed. Additionally, the dieless drawing limit decreases with increasing drawing speed. In order to enhance dieless drawing limit, it is necessary to decrease the strain rate in deformation area, so that it is important to lead to gradual deformation profile in deformation area. Secondarily, dieless drawing experiments with expansive induction heating coil for gradual deformation profile are conducted. The result shows that expansion of the heating coil changes deformation profile into gradual, so that the mean strain rate decreases with increasing heating length. Consequently, it is suggested that the dieless drawing limit can be enhanced with decreasing the strain rate due to more gradual deformation profile, and the evaluation of effectiveness of dieless drawing for fabrication of microtubes is discussed.
Microtube Dieless drawing Deformation profile Strain rate Heating band
Tsuyoshi FURUSHIMA Yuta NODA Ken-ichi MANABE
Department of Mechanical Engineering, Tokyo Metropolitan University 1-1 Minami-ohsawa, Hachioji, Tokyo, Japan
国际会议
2nd Asian Workshop on Macro/Nano Forming Technology(AWMFT-2009)(第2届亚洲微米纳米技术研讨会)
长沙
英文
640-643
2009-10-25（万方平台首次上网日期，不代表论文的发表时间）