Drum brake shoe double-station automatic outer arc grinding machine

The utility model discloses a double-station automatic external arc grinding machine for drum brake shoes. The double-station automatic external arc grinding machine comprises an operation platform, apressing plate folding and unfolding mechanism, a pressing plate, a pressing plate pressing mechanism, a grinding mechanism and a hoisting mechanism used for carrying the brake shoes. Two workpiece positioning tools are arranged on the working platform, a hollow rotating shaft is arranged on one side of each workpiece positioning tool, and a grinding positioning tool is arranged at the upper endof each rotating shaft. Workpiece correcting mechanisms are arranged on the two sides of the grinding positioning tool. The pressing plate folding and unfolding mechanism comprises a pressing plate advancing and retreating air cylinder, a lifting arm lifting air cylinder and a lifting arm, the lifting arm is fixed to an end plate of the lifting arm lifting air cylinder, and electromagnets are arranged at the two ends of th