Clamp for turning outer circle of gearbox shell and application of clamp

The invention discloses a fixture for turning the outer circle of a gearbox shell. The fixture comprises a fixture bottom plate, and a pre-guiding sizing block is fixedly connected to the top of the fixture bottom plate; a positioning pressing plate assembly is assembled and connected to the center of the top of the clamp bottom plate. The positioning pressing plate assembly comprises a pressing rod assembled on the clamp bottom plate, and an auxiliary positioning pressing plate is assembled and connected to the upper end of the pressing rod. The top of the pressing rod is in threaded connection with a nut, and the auxiliary positioning pressing plate is positioned through the nut. A plurality of workpiece side edge abutting parts are assembled and connected to the top of the clamp bottom plate, and when a gearbox shell workpiece is placed on the clamp bottom plate, the workpiece side edge abutting parts abut against the side edge of the gearbox shell workpiece. The invention further discloses application of