圆（柱）形的接管与简体垂直相贯（它们的轴线相交）简称为管筒直交。这种结构在工程上应用十分普遍。管简直交（包括其它相贯方式）相贯线是一个空间曲线、但管与简都可展开为平面，因而它们的相贯线皆可转换成平面曲线。只要合理地建立坐标，均可建立相贯线展开的函数式。一 Circular (column) -shaped pipe and simplified vertical intersection (their axes intersect) referred to as the tube straight. This structure is very common in engineering applications. Intersection is a spatial curve, but the tube and the simple can be expanded into a plane, so that their intersection line can be converted into a planar curve. As long as a reasonable establishment of coordinates, can establish the function of the expansion of the intersecting line. one