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摘要
With the ever-increasing demands on miniaturization, the requirement on good forming quality and high-dimensional accuracy of micro-parts is dramatically motivated. As a decisive factor affecting the accuracy of micro-bent parts, the springback is significantly influenced by size effects. In order to explore size-effect-associated springback behaviour and evaluate the forming quality of micro-bent parts, an experimentally based investigation on the influence of foil thickness, grain size and their interactive effect on the springback behaviour of CuZn37 brass foils with different thicknesses and grain sizes was carried out. The experimental results obtained via micro-tensile tests revealed that the yield strength, Young's modulus and elongation had a close correlation with the thickness-to-average-grain-size ratio. A micro W-bending process was used to perform the bending tests. Both springback and negative springback phenomena were observed. It was found that how size effects may influence the amount of springback would depend on the springback behaviours, for example, positive springback or negative springback. In addition, scatter phenomenon of the springback behaviour was analysed quantitatively. An increased scatter was observed for the 50-mu m-thick specimens when the thickness to average grain size decreased, whereas an inverse tendency of the decreased scatter of the negative springback was found for the 75- and 100-mu m-thick specimens with the increase in the grain size. Finally, forming quality of the W-shaped micro-bent parts was assessed.
