Positioning mechanism for press machine

The utility model relates to the technical field of press machines, in particular to a positioning mechanism for a press machine, which comprises a press machine body and a workbench. The workbench is arranged above the press machine body, two frame rods are transversely and fixedly connected to the top of the workbench, sliding plates are slidably connected to the tops of the two frame rods correspondingly, a first guide block and a second guide block are fixedly connected to the bottoms of the two sliding plates correspondingly, and a supporting plate is fixedly connected to one side of each sliding plate. The top of the supporting plate is fixedly connected with an air cylinder, the output end of the air cylinder is fixedly connected with a clamping plate through the supporting plate, the first guide block and the second guide block are inserted into the frame rod, and once the frame rod is fixedly connected with a motor, when the part, needing to be machined, of a plate is moved to the machining head of t