用管状毛坯制造空心零件的产量逐年增加。但得到这种毛坯的方法(如机床切割、摩擦锯切割及其他方法),按其技术指标来说,往往不能满足生产发展的需要。这些方法虽然有其工艺性广和毛坯质量高等不可否认的优点,但也有本质上的缺点:生产率低、废料多、工具寿命短。 The production of hollow parts from tubular blanks is increasing year by year. However, the method of obtaining such blank (such as machine tool cutting, friction saw cutting and other methods), according to its technical indicators, often can not meet the needs of production development. Although these methods have the undeniable merits of wide technology and high quality of blank, they have the essential disadvantages of low productivity, more scrap and short tool life.