Clamping device for mechanical part machining

A clamping device for mechanical part machining comprises a workbench, supporting plates, a to-be-machined part, a left limiting plate, a rotating pressing plate, a hydraulic jacking cylinder, a fixing base, a mounting base, a rotating holding plate, a connecting plate and a sliding jacking rod, the lower portion of each supporting plate is connected with the workbench, the lower surface of the to-be-machined part is attached to the supporting plates, and the supporting plates are distributed on the lower portion of the to-be-machined part; the supporting plate is provided with supporting plate protruding plates, the side faces of the to-be-machined part are attached to the supporting plate protruding plates, the supporting plate protruding plates are symmetrically arranged on the front side and the rear side of the to-be-machined part, the lower portion of the left limiting plate is connected with the workbench, the left side face of the to-be-machined part is attached to the left limiting plate, and the upp