1. Firstly eliminate the silt with broken screws and cut off the surface layer. Then use the center gun to kill the center of the cross section.After drilling through the hole, remove the small bit, replace the 16mm diameter bit, and expand the hole of the broken bolt again and drill through.

2. Take the following wire diameter of 3.2 mm to choose small and medium electricity flow in the broken bolt holes from the inside out in the beginning of the overlaying welding position to take half of the total length of broken bolt can. Don't be too long in case began when the welding arc burning through the broken bolt face. Welding to the broken bolt hole after surfacing again a 14-16 mm diameter cylindrical high 8-10 mm.

3. After surface welding, hammer the inner hole with a hand hammer to make the broken bolt vibrate along the radial direction of the bolt. The heat caused by the previous electric isolation and the subsequent cooling, together with the vibration at this time, will cause the bolt to loosen between the external thread of the body and the broken bolt.

4. After observation, when the trace analysis of rust is found after knocking, it can take the M18 nut to cover the surfacing column and weld the two together.

5. After welding and drying for a while while it is hot, use a spanner to set the nut up and down and shake it back and forth. You can also shake it back and forth while hitting the hole in the nut with a hammer with both hands so that the broken bolt can be removed.6. Remove the broken bolt and process the wire mouth in the sound card frame with a suitable wire hammer to remove the hole wall rust and other dirt.