科研之友
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摘要
Miniaturization of micro blanking process caused changes in the relative contribution of relevant process parameters and the grain size of metal foil reaches the same order with the blanking clearance. As a result, the size effects occur, which is different from the other micro forming processes, such as micro upsetting, micro tensile, and micro bending. In the paper, the size effects of micro blanking of metal foil with miniaturization were investigated. Similar to the traditional blanking process, the micro blanking process is still composed of three stages of elastic deformation, plastic shearing deformation, and fracture separation. However, the maximum blanking force appeared at punch stroke of foil thickness, which is much larger than the transitional blanking process of 1/3 of work material thickness. The cross section of micro-hole is also composed of rollover, smoothly shearing zone, fraction zone, and burr. But the distribution of the fraction zone and burr is uneven, which is caused by the influence of the material anisotropy with the decreasing of the foil thickness. The results show that the ultimate shear strength of micro blanking is decreasing with the increasing of the length scale lambda, not only for the brass foil, but also for the stainless steel foil. The fracture mechanism of micro blanking of brass foil is significantly changed from shear dimple to slip separation with the decreasing of length scale lambda, but the fracture mechanism of micro blanking of stainless steel is not changed and kept ductile fracture with equiaxed dimples
- 出版日期2011-9
- 单位哈尔滨工业大学
