| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 96 === Fine blanking is widely used in stamping process. Fine blanking products have many advantages, like high precision, high rigidity and secondary process is not needed. However, in micro scale, the investigation of the influence of each parameter of fine blanking process on the shearing surface is still needed.
This thesis studies the fine blanking process of C2600 brass sheet with thickness 0.4mm. The finite element analysis was conducted for the simulation in fine blanking. The influence of different levels of thickness/grain size ratio, clearance, blank holder force and counterpunch force on the shearing surface is evaluated by Taguchi method. The material tests of the sheets with different grain sizes were performed and the flow stresses and critical fracture values were obtained and then were input into DEFORM 2D software to simulate the fine blanking process. The accuracy of
fracture criteria was studied. Finally, fine blanking experiments were carried out, and compared with the results of the simulation.
The results indicate that Ayada criterion, considering hydrostatic pressure, has better prediction for fine blanking simulation of micro sheets. The thickness/grain size ratio and blank holder force have greater effect on
shearing surface quality than the counterpunch force do. In addition, for getting complete burnish surface, the clearance should be least within 2% of the sheet thickness.
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