近来,液压胀形成形技术已成功地引用于焊接管 T 形接头、自行车三角架前接头和中接头以及汽车排气管接头等等的大批生产中。然而,这种方法用在汽车差速器壳体的胀形中,需要对延用模具作许多改进。延用模具表示于图1(a)。如果图1(b)中 Lm 大时,模具与管子间的接触面识较大,内胀力在这些面积上引起的摩擦力随之增大。因此,作轴向压缩的内滑塞杆作用于工件端部产生的轴向力,抵消摩擦力后对要胀形的部位就再不起有效作用。在模具(b)结构中,芯 Recently, hydraulic bulge forming techniques have been successfully used in mass production of welded pipe T-joints, bicycle tripod front and center joints, and automobile exhaust pipe joints and the like. However, this method is used in the bulging of the automobile differential case, and many improvements are needed to extend the mold. Extension mold shown in Figure 1 (a). If Lm in Fig. 1 (b) is large, the contact surface between the mold and the pipe is large, and the frictional force caused by the inner expansion force in these areas increases accordingly. Therefore, the axial compression of the inner slide rod acting on the end of the workpiece axial force, to offset the friction force to bulging the area will no longer have an effective role. In the mold (b) structure, the core