Common welding methods:
1, traditionally, copper and aluminum are welded by hanging tin and melting tin. This method is not well formed and has no good strength. Because of the low melting point of tin, it can't be welded to the workpiece working at high temperature, so this technology is only suitable for small workpieces at low temperature (only suitable for welding multi-strand copper wires and small-size aluminum enamelled wires), and it is difficult to be applied to the production of other products.
2. When welding copper and aluminum by welding methods such as fusion welding, friction welding, cold pressure welding, explosive welding, electron beam welding and ultrasonic welding, the welded joint is brittle, and cracks and pores are easy to occur, and the welded workpiece will inevitably break, which may break the conductor and make the pipeline leak, so the required effect is often not achieved in actual production.
3. Copper and aluminum are welded together by brazing (usually by flame brazing, furnace brazing and high frequency brazing). ), and copper and aluminum are welded together by brazing process with solder as the intermediate medium (in fact, metallurgical reaction occurs, and solder penetrates into the molecular structure of copper and aluminum through capillary action). After welding, the joint is well formed, with good tensile and shear properties, good conductivity and corrosion resistance. It is a common welding method of copper and aluminum at present, and the solder that can be used for copper and aluminum welding on the market is from Shanghai.
Introduction of copper-aluminum brazing method;
Before welding, thoroughly remove oil, dirt, insulation, etc. On the basic materials; When welding, the base material is heated first, then the thick part is heated, and then the thin part is heated; Firstly, heating the copper parts, and then heating the aluminum parts; Move the welding gun back and forth to evenly heat the welding part. When the temperature of the weldment reaches 450-500℃, add the welding wire to the welding position to make the welding wire melt evenly and flow into the weld (it is not allowed to direct the flame at the welding wire for heating, and the welding wire is melted mainly by the temperature of the base metal). Then gently sweep the welding part with flame to ensure the spreading and positioning of solder at the welding part, remove the welding torch and let it cool naturally, and then complete the welding.
Introduction to the use of copper-aluminum solid-core welding wire and copper-aluminum solder paste;
Suitable for welding large-area copper-aluminum bars, foils and large-diameter copper-aluminum pipes. Before welding, the oil stain, dirt and insulation layer of the base material should be thoroughly removed. Copper-aluminum solder paste can be evenly coated on the welding part with a brush, and the copper-aluminum base material should be sealed to keep the weldment flat. The weldment should be fixed with a suitable fixture, and the thick part should be heated first, and then the thin part should be heated with flame. Heat the copper parts first, and then heat the aluminum parts to ensure that the weldments are heated evenly. When heating, it can be seen from the weld that the solder paste first changes from paste to white solid, and then continues to heat. When the solid becomes liquid, the solder paste reaches the active temperature, and the welding wire is added to the weld in time. When the welding seam is full of solder, the welding position is lightly swept by flame, so that the residual solder is discharged from the welding seam to avoid slag inclusion. Take off the welding gun and wait for the workpiece to cool naturally to complete welding.