在生产中,当用正常翻边所形成的筒壁,不能达到制件的要求高度时,就可采用变薄翻边。这种翻边方法具有节省原材料的优点。要使壁都产生很大的变薄,需预先冲孔。然后在压力机的一次行程中(当闭合高度不够时,也可两次),将翻边材料厚度逐渐变薄,使其达到所要求的翻边高度。在这里首先遇到的是计算变薄翻边预冲孔的直径问题。教科书和参考书上对常用翻边 In production, when formed with the normal flange of the cylinder wall, can not reach the required height of the workpiece, you can use thin flange. This flanging method has the advantage of saving raw materials. To make the walls have a great thinning, pre-punching. Then in a stroke of the press (when the closing height is not enough, it may be twice) to reduce the thickness of the flange material to the required flange height. The first problem encountered here is the calculation of the diameter of the reduced burring pre-punched hole. Textbooks and reference books on the common flanging