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在拉延过程中,为了防止工件的边壁或凸缘起皱,应使毛坯在被拉入凹模圆角以前保持稳定状态。在毛坯相对厚度较小的情况下,经常采用压边圈压边。但压边的压力应该适当,如果压边力过大,就会增加毛坯危险断面的拉应力,引起严重变薄超差甚至拉裂破坏,当压边力过低时,则防皱的效果不好而产生废品, 根据资料介绍,在拉延过程中,凸缘起皱的趋势是变化的,其变化规律与最大拉应力的变化相似。事实上,要使压边装置产生的压边力按需要的变化规律而变化是十分困
In the drawing process, in order to prevent the workpiece wall or flange wrinkles, the rough should be pulled into the die before fillet to maintain a stable state. Blank relatively blank in the case of relatively small, often using blank holder crimping. However, the pressure of the blank holder should be appropriate. If the blank holder force is too large, it will increase the tensile stress of the blank dangerous cross-section, causing serious thinning and even the tensile failure. When the blank holder force is too low, Good and produce waste, according to the information introduced in the drawing process, the trend of wrinkling flange changes, the variation of the maximum tensile stress and similar changes. In fact, it is very difficult to make the blank holder force generated by the blank holder change according to the changing rule