The article mainly talks about the characteristic of common and fine punching and the quality of shearing edge. Although the common punching has been widely applied, the quality of shearing edge is very poor. The fine punching work-piece is better in quality. But it isn’t still been widely applied, because the structure of die is complicated and the manufacture of die and using pressure machine are expensive. A new fine punching processing without burr is put forward by discussing the plastic status and press stress status of the material which influence the quality of the punching work-piece in the deformation zone, it provides the plastic status of material to determine the parameter in the new processing and presents the maximum value of plastic deformation specific energy when the material reaches the plastic status. The author has analyzed the initializing clearance and instantaneous clearance of the ordinary punching. The instantaneous clearance of the ordinary punching process is instable. By studying the author brings forward a kind of punching process which initializing clearance and instantaneous clearance are stable, that is the negative clearance fine punching process. Because of using the negative clearance fine punching process, the material of sheared distorting section comes into the plastic state. The surface quality of the punching sheared edge is advanced 1.5 times than that of the ordinary punching. The recommended value of depth of the negative clearance punching has been given in this article.
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