Investigation on dimensional accuracy in micro cross wedge rolling of metals
A novel microforming process - Micro Cross Wedge Rolling (MCWR) has been developed. It is a very promising technology in the field of microforming due to its advantages such as high product rate and minimised material consumption. How to control geometrical accuracy of the produced micro parts is one of the major challenges in the development of microforming technology. Geometrical accuracy was still concentrated in term of springback. When the wedge tools loads are removed after forming step, a portion of the deformation recovers, which causes a change in the shape of micro parts. In other word, springback happens, which should be determined and controlled especially in microforming technology. A series of MCWR experiments of pure copper and aluminium have been carried out using the machine designed by authors in this study. Cylindrical workpieces were deformed into stepped shafts with cross-sectional area reductions of 35, 52.73 and 75%. Corresponding finite element simulation has also been conducted in consideration of the size effect on the material flow. The springback was proposed to account for the geometrical error of micro products. The effect of grained heterogeneity on the height of surface asperity after rolling was assessed quantitatively.
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