一般来说,带底的矩形件都是采用引伸的方法成型。但如图1所示,此矩形件为不带底的,其高度按设计要求有几种尺寸;最长为86mm,最短为67nlm。材料Ly—12,此种零件如果采用弓伸的方法制造,必需经 In general, the rectangular pieces at the end are formed by extension. However, as shown in Figure 1, the rectangular piece is not bottomed, and its height according to the design requirements of several sizes; the longest is 86mm, the shortest is 67nlm. Material Ly-12, such parts if the bow extension method of manufacturing, must pass through