以具有外胀式套筒的夹紧机构为研究对象。设液性介质无压力时夹具套筒(下面筒称套筒)外壁与工件孔壁之间存在径向间隙△_0[mm]如图1所示。当液性介质达到工作压力p[MP_a]时,若套简不受工件孔壁约束自由扩涨,它的直径将产生扩涨△_m[mm]。实际上由于工件孔壁的限制,套筒直径真实扩涨量为△_c,(△_0<△_c<△_m)。这相当于套筒与工件形成过盈配合,过盈量为(△_m—△_0)[mm],两者接触面之间产生 Taking the clamping mechanism with the expansion sleeve as the research object. Suppose there is no radial pressure Δ_0 [mm] between the outer wall of the fixture sleeve (below the sleeve called the sleeve) and the hole wall of the workpiece. When the liquid medium reaches the working pressure p [MP_a], if the sleeve is not free to expand restrictions by the hole wall of the workpiece, its diameter will produce expansion △ _m [mm]. In fact, due to the limitation of the hole wall of the workpiece, the real expanding diameter of the sleeve is △ _c (△ _0 <△ _c <△ _m). This is equivalent to the sleeve and the workpiece to form an interference fit, the amount of interference is (△ _m- △ _0) [mm] between the two contact surface