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对于薄壁圆筒胀形加工,如果在内压P作用的同时施加轴向压力Q,则可使工件沿子午线方向产生一压应力σ_3,从而改变简单胀形中双向受拉的应力状态而成为一拉一压(图1),这有利于材料的塑性变形,可促使筒坯沿轴向压缩,故能够获得较高的变形程度和成形质量。据资料介绍,在有轴向压力作用时,胀形系数K(K=胀形后直径/筒坯直径)对于不锈钢可达1.6～1.7、低碳钢可达1.4～1.5,而简单胀形的胀形系数不锈钢为1.26～1.32、低碳钢为1.15～1.2。 带有轴向力的胀形,常采用液压成形装置,图2是示意图。通常使用的波纹管液压
For the thin-walled cylindrical bulging process, if the axial pressure Q is applied while the internal pressure P is acting, a compressive stress σ_3 may be generated along the meridional direction so as to change the stress state of the bidirectional tension in the simple bulging to become a pull A pressure (Figure 1), which is conducive to plastic deformation of materials, can promote the axial compression of the billet, it can get a higher degree of deformation and forming quality. According to the information, under the action of axial pressure, the coefficient of expansion K (K = diameter after bulging / diameter of tube) can reach 1.6-1.7 for stainless steel and 1.4-1.5 for mild steel, while the simple bulging Bulging coefficient stainless steel is 1.26 ~ 1.32, low carbon steel is 1.15 ~ 1.2. Bulging with axial force, often using hydroforming device, Figure 2 is a schematic view. Commonly used bellows hydraulic