前已述及,一般情况下应优先选用双圆柱来代替V形架,定位圆柱的结构形式如图19所示。定位圆柱的结构形式主要有四种:图19a为基本形式,这种形式的两只定位圆柱的组合作用相当于一个短V形架,可限制工件的二个自由度。图19b为长定位圆柱,二只长定位圆柱的组合作用相当于一个V形架,可限制工件的四个自由度。图19c为带轴向定位台阶的短圆柱,二只组合起来的作用相当于一个短V As mentioned before, under normal circumstances should be preferred to replace the double-cylinder V-shaped frame, positioning the cylindrical structure shown in Figure 19. There are mainly four types of positioning cylinders: Figure 19a shows the basic form. The combination of two positioning cylinders in this form is equivalent to a short V-shaped frame that limits the two degrees of freedom of the workpiece. Figure 19b shows a long positioning cylinder. The combination of two long positioning cylinders is equivalent to a V-shaped frame, which can limit the four degrees of freedom of the workpiece. Figure 19c shows a short column with an axial positioning step, the two combined acting as a short V