Automatic feeding and discharging device of printing machine

The utility model relates to the technical field of printing, in particular to a printing device which comprises a conveyor, a printing machine is fixedly installed on the top of the conveyor, material tables are fixedly installed at the left end and the right end of the bottom of the conveyor, the material tables are rectangular, the ends, away from the conveyor, of the material tables are open, supports are fixedly installed on the tops of the material tables, and installation bases are fixedly installed on the tops of the supports. The mounting seat is U-shaped, two ends of the mounting seat are rotatably connected with screw rods, a motor is fixedly mounted on one side, far away from the conveyor, of the mounting seat, an output shaft of the motor is connected with the corresponding screw rod, the outer wall of the screw rod is in threaded connection with a moving block, a cylinder is fixedly mounted at the bottom of the moving block, and a pneumatic vacuum chuck is fixedly mounted at the bottom of the cy