Clamping tool for grading ring machining

The clamping tool comprises a clamping base, a positioning structure used for sleeving a top ring body and two clamping jaws used for clamping a bottom ring body, the positioning structure comprises a fixed cone frustum and a plurality of movable positioning columns, the fixed cone frustum is fixedly connected to the upper end face of the clamping base, and the movable positioning columns are fixedly connected to the lower end face of the clamping base. The movable positioning column is coaxially placed at the top of the fixed cone frustum, an assembling groove allowing the top of the fixed cone frustum to enter is formed in the bottom face of the movable positioning column, the fixed cone frustum is arranged in the assembling groove, the side face of the assembling groove is attached to the arc-shaped side face of the fixed cone frustum, and the movable positioning column is detachably connected with the clamping base through a movable threaded cover; according to the utility model, by utilizing the structur