The Study On The Microstructure Flow And Hardening In Fine-blanking With Negative Clearance

Fine-blanking with negative clearance is one of fine-blanking technologies, its unique make it can be used in ordinary blanking machine and achieve precision blanking. Because low cost, high efficiency, the range of applications is wide and outlook is relatively good. It is generally applied to the field of sheet metal forming.The paper further studied the fine-blanking with negative clearance process material changes and the hardening of blanking piece cross-section by analysing punch stroke and force, blanking piece cross-section microstructure changes of fine-blanking with negative clearance, under the principle of metal plastic forming. In addition, the paper also used the rigid-plastic large deformation finite element method(FEM), simulating the whole process of fine-blanking with negative clearance by DEFORM to predict the damage and deformation under different blanking clearances and reserve volumes.This paper take Q235 steel, 20Mn steel, stainless steel, chrome bronze and other materials as studied objects, the curve of hardening of blanking piece cross-section and blanking punch stroke was ploted. The blanking process and work-hardening changes by the curves from mechanics were understanded. Metallofraph of fine-blanking with negative clearance in rollover zone, fracture band, burr zone, shear zone, etc were observed by optical microscopy, scanning electron microscope. The changes of blanking piece cross-section microstructure and micro-morphology were observed and the whole process of fine-blanking with negative clearance was further analysed.A large number of experimental datas and experimental photographs provide a basis for the fine-blanking with negative clearance process research and analysis. The research and analysis of this paper further evidence the material extrusion forming principle of fine-blanking with negative clearance. The degree of hardening, cross section quality were increased and the area of brightness was expanded in the fine-blanking with negative clearance.The combination of theoretical analysis and scientific experiments make the analysis of fine-blanking with negative clearance process more in-depth, which helps to comprehensive grasp the deformation mechanism and crack propagation mechanisms of fine-blanking with negative clearance process, and optimize it, improve the quality of blanking piece cross-sections and labor productivity. This study will deeper the study of fine-blanking with negative clearance, make it more conducive in the industrial production.