Positioning device and method for semi-closed cone annular groove machining

The invention discloses a positioning device and method for machining a semi-closed cone annular groove. The positioning device comprises a fixing ring and a base which are arranged in an up-down spaced mode. The fixing ring and the base are connected through a plurality of vertical stand columns. The fixing ring is used for being arranged on the cylindrical surface section of the mounting edge of the cone part in a sleeving mode, and the top face of the fixing ring is used for abutting against the step face of the mounting edge of the cone part. A plurality of bolt holes are evenly distributed in the fixing ring, and bolts are assembled in the bolt holes. The method comprises the following steps that the positioning device is installed on a workbench of the numerical control vertical lathe and fixed; the cone part is placed in a positioning device, the cylindrical surface section of the mounting edge of the cone part is sleeved with a fixing ring in the positioning device, and the top face of the fixing ring