Fabrication of Miniature Shell Structures of Stainless Steel Foil and Their Forming Limit in Single Point Incremental Microforming
Toshiyuki Obikawa* and Tsutomu Sekine**
*Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
**Department of Precision Engineering, School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan
Single Point Incremental Microforming (SPIMF) using neither dies nor a backing plate is applied to the fabrication of miniature shell structures of stainless steel foil in meso-scale. A piece of 8 µm-thick blank, which is held in a blank holder on a desktop forming machine, is incrementally formed with a thin, round-tip tool. Three kinds of polygonal pyramids are formed, and their forming limits are compared to those when 12 µm-thick aluminum foil is used. It is found that the forming limit of stainless steel foil in forming pyramids depends only on the tensile strain of a triangular lateral face, whereas that of aluminum foil depends on the sum of two principal tensile strains on the surface of a rounded lateral edge. It is also found that the forming limit of stainless steel foil can be drastically increased by SPIMF.
-  T. Obikawa, S. Satou, and T. Hakutani, “Dieless Incremental Micro Forming of Miniature Shell Objects of Aluminum Foils,” Int. J. of Machine Tools and Manufacture, Vol.49, pp. 906-915, 2009.
-  T. Sekine and T. Obikawa, “Single Point Micro Incremental Forming of Miniature Shell Structures,” J. of Advanced Mechanical Design, System and Manufacturing, Vol.4, pp. 543-557, 2010.
-  T. Obikawa, T. Hakutani, T. Sekine, S. Numajiri, T. Matsumura, and M. Yoshino, “Single-Point Incremental Micro-Forming of Thin Shell Products Utilizing High Formability,” J. of Advanced Mechanical Design, System and Manufacturing, Vol.4, pp. 1145-1156, 2010.
-  M. Arai and T. Ogata, “Development of Small Fatigue Testing Machine for Film Materials,” Trans. of Japan Society of Mechanical Engineers (A), Vol.68, pp. 801-806, 2002. (in Japanese)
-  J. Jeswiet, F.Micari, G. Hirt, A. Bramley, J. Duflou, and J. Allwood, “Asymmetric Single Point Incremental Forming of Sheet Metal,” Annals of the CIRP, Vol.54, pp. 88-114, 2005.
-  H. Iseki, “An Approximate Deformation Analysis and FEM Analysis for the Incremental Bulging of Sheet Metal Using a Spherical Roller,” J. of Material Processing Technology, Vol.111, pp. 150-154, 2001.
-  K. Jackson and J. Allwood, “The Mechanism of Incremental Sheet Forming,” J. of Material Processing Technology, Vol.209, pp. 1158-1174, 2009.
-  W. C. Emmens and A. H. van den Boogaard, “Cyclic Stretch-Bending: Mechanics, Stability and Formability,” J. of Material Processing Technology, Vol.209, pp. 196singlesingle5-1981, 2011.
This article is published under a Creative Commons Attribution-NoDerivatives 4.0 Internationa License.