By analyzing machining error that made by installing tool on higher position and quantitative law in turning cone, two countermeasures are put forward, and macroprogram is utilized to eliminate the error.

The definition of conicity of a cone is presented.

As for the point data are affected by noise in point cloud,the initial estimates are usually unstable that often leads to failure or incorrect result in the process of fitting point cloud to cone or cylinder.

Parameterization drawing on intersection curve of cone surface and oblique helic oids based on the circular arc projection method;

The parameter equation for the projection of the traverseline of the ring surface through the cone surfaceand its application in computer graphing;

When cylinder surface and cone surface penetrate each other,if their axises intersect slantly and are parallel to the frontal projecting plane,there will he special points in the penetrating line.