Machining method for offset milling of conical outer surface of casing

The invention relates to a machining method for offset milling of the conical outer surface of a casing. The method comprises the following steps that UG software is used for compiling milling operation of the conical outer surface of the casing; the milling sequence and the tool path of the conical outer surface of the casing are planned; a special post processing program of the UG software is customized; the special post processing program is used for creating a G code program recognized by a machine tool; the milling sequence and the tool path of the conical outer surface of the casing are planned as follows: the conical outer surface of the casing is divided into multiple curved face areas, each curved face area serves as an independent drive body, each curved face area is shown with (U,V) parameters, the feed point selects the middle position of each curved face area, and the included angle theta between the feed direction and the cutting direction is greater than 90 degrees but smaller than 270 degrees. The cutting angle of a tool is improved, the cutting range of a side edge is enlarged, cutting of a bottom edge is reduced, and therefore abrasion of the tool is reduced, the machining efficiency is improved, and the numerical control milling problem of the conical outer surface of the casting is successfully solved.