1. First, remove the sludge on the surface of the broken screw head, use the center clamp to kill the center of the section, and then use an electric drill to install a drill bit with a diameter of 6-8 mm, drill a hole in the center of the section, pay attention to the hole must be drilled. After the hole is drilled, the small drill bit is removed, replaced with a drill with a diameter of 16 mm, and the hole of the broken bolt is continued to be enlarged and drilled through.
2. Take the welding rod with a diameter of 3.2 mm or less, use small and medium current, in the drilling hole of the broken bolt from the inside to the outside for surfacing welding, and take half of the entire length of the bolt.
3. After surfacing welding, hammer its end face with a hand hammer to make the broken head bolt vibrate along its axial direction. Due to the heat generated by the previous arc and the subsequent cooling, coupled with the vibration at this time, the broken bolt will loosen the thread between the broken bolt and the body.
4. Observe carefully, when it is found that a trace amount of rust leaks out from the fracture after knocking, you can take the nut of M18 and put it on the column head of the surfacing weld, and weld the two.
5. After welding, slightly cool, while hot, use a plum wrench glove to twist back and forth on the nut, or you can use a small hand hammer to hit the end face of the nut while twisting back and forth, so that the broken bolt can be taken out.
6. After taking out the broken bolt, use a suitable tap to process the wire buckle in the frame to remove rust and other debris in the hole.