Use a copper tube, flatten eight copper wires and flat copper wires that are sleeved side by side in the copper tube with a hammer, and then punch a few holes in the flattened copper tube with a foreign punch for anti-loosening treatment.

Finally, the copper tube is heated with an electric soldering iron, and the solder is melted and filled from the gap of the copper tube. This method has the advantages of less equipment, low cost, simplicity and reliability.

Because the copper wire is too thin, it is easy to blow off when welding with oxygen, and it is not easy to weld. If welding with a copper welder, intermittent heating is needed to prevent overheating from burning the copper wire.

The thread end can be directly melted and welded by gas welding, and a small welding gun can be used. If you feel unsafe, use silver-copper gas welding, or use copper welding machine and 303 silver welding piece for welding.

Flat copper wire can be called conductive ring. Copper wire can be wound on the flat copper wire (or a layer of copper wire can be wound on the wound copper wire for reinforcement), and then it can be reinforced by soldering (if there is no electric soldering iron with power greater than 200W, it can be slightly heated with oxygen before welding) or silver-copper welding.