In the figure: 1 face guard, 2 casings, 3 backplate, 4 magnetic cores, 5 spring locks, 6 handles, 7 insulator, 8 first dodge holes. In the application, the face shield 1, the shell 2 and other structural components are made of fireproof materials, the surfaces of the PCB and the luminotron are subjected to special fireproof treatment, and