用一般的挤压方法挤制管材时,通常要使用比管径大的坯料,因而必须大能量的设备,且因管壁厚度取决于挤压模内径和挤压杆外径之差,它们的中心轴线难以重合,故存在大的壁厚差。针对上述存在问题,几年前(1976年)Rowell 提出了拉夫洛(Raflo)挤压法。拉夫洛挤压法原理见图1。图1 a 可视为第一阶段成形、挤压时,坯料从模子的扩展平面与比挤压简内径大的紧固心棒端平面间隙 When extruding a pipe by a usual extrusion method, it is usually necessary to use a material having a larger diameter than that of a pipe. Therefore, a large-sized equipment is required. Since the thickness of the pipe depends on the difference between the inner diameter of the extrusion die and the outer diameter of the extrusion rod, Center axis difficult to coincide, so there is a big difference in wall thickness. In response to the above problems, Rowell proposed Raflo squeeze several years ago (1976). Love Lu squeeze method shown in Figure 1. Figure 1 a can be considered as the first stage of forming, extrusion, the blank from the mold of the expansion plane and the extrusion diameter larger than the diameter of the fixed mandrel plane end clearance