With the rapid development of my country’s electric power, the requirements for copper-aluminum butt joints are becoming more and more widely used and the requirements are getting higher and higher. Common copper-aluminum welding processes on the market today include: flash butt welding, rolling friction welding and brazing. The following editor will introduce the characteristics of these processes for you.
Friction rolling welding is currently only limited to welding bars, and welded bars can also be forged into plates, but it is easy to cause cracking of interlayers and welds.
Brazing is widely used, and it is mostly used for large-area and irregular copper-aluminum butt joints, but there are factors such as low fastness, low efficiency, and unstable quality.
Flash butt welding is currently the best way to weld copper and aluminum. Flash butt welding has high requirements on the power grid, and there is still burning loss. However, the welded workpiece has no pores and dross in the weld seam and the strength of the weld seam is very high. It can be seen that its disadvantages are obvious, but its advantages have overshadowed its disadvantages.
The copper-aluminum flash welding butt welding process is complex, and the parameter values are various and intricately restricting each other, each of which will affect its welding quality. At present, there is no good detection method for the quality of copper-aluminum welding, and most of them implement destructive detection to ensure its strength (reaching the strength of aluminum material), so that it can operate reliably in the power grid.
Requirements for welding materials of copper-aluminum butt welding machine
1. Material requirements of flash butt welding machine;
The grade of welding consumables should not be lower than the standard
2. Change to flash butt welding machine material surface requirements:
There should be no oil stains and other substances that affect conductivity when welding on the surface of the parts, and there should be no paint on the welding end surface and both sides.
3. Change to flash butt welding machine material preliminary preparation requirements:
When the strength of the material is too high, it must be annealed first to ensure low hardness and high plasticity of the weldment, which is conducive to the extrusion of liquid metal slag during upsetting.
4. Change to the material size of the flash butt welding machine;
When selecting the thickness of the welding workpiece according to the weldable size of the welding machine, select a negative value for copper and a positive value for aluminum (generally 0.3~0.4). The thickness difference between copper and aluminum should not exceed this value, otherwise it will cause insufficient or excessive upsetting flow, which will seriously affect the welding quality.
5. Requirements for material section of flash butt welding machine:
The end face of the weldment should be flat, and the cutout should not be too large, which will cause uneven heat generation at both ends of the weld and cause uneven weld
6. Flash butt welding machine workpiece blanking size:
When blanking the weldment, the amount of flash burning and upsetting should be added to the drawing according to the welding process.