Defect repair mechanism of metal surface repair machine Due to the strong chemical activity of aluminum and its alloys, it is easy to form oxide films on the surface, and most of them are refractory (for example, the melting point of Al2O3 is about 2050 °C, and the melting point of MgO is about 2500 °C). ) In addition, aluminum and its alloys have strong thermal conductivity, and it is easy to cause non-fusion phenomenon during welding. Since the specific gravity of the oxide film is very close to that of aluminum, it is also easy to become inclusions in the weld metal. At the same time, aluminum and its alloys have a large coefficient of linear expansion and strong thermal conductivity, and are prone to warping deformation during welding. This is a difficult problem when welding aluminum and its alloys. At present, the most commonly used argon arc welding in fusion welding relies on "cathode atomization" to break the oxide film, and under the protection of argon gas, the oxide film cannot be regenerated. However, when welding the aluminum alloy after heat treatment strengthening, the strength of the near seam area is greatly weakened, and warpage deformation will inevitably occur. The metal surface repairing machine is mainly used to repair casting defects. It consists of an inverter high-frequency + pulse power supply, a welding torch that can rotate the welding wire at a high speed, and a control part. The mechanism of repairing defects is as follows: using high frequency + pulse voltage to break down the gas to form a plasma gas, thereby generating an electric spark with a temperature of over 6000 ℃, and the electric spark will instantly (10-5 -10-6 seconds) and the base metal in contact with it are melted at the same time, relying on the combined action of the instantaneous high temperature and the mechanical friction between the rotating welding wire and the base metal and the rotating electric field force, the oxide film is broken, and under the protection of argon, the oxide film is broken. The film cannot be regenerated, thereby completing the metallurgical bonding of the wire to the base metal. Due to the short action time of the electric spark, the base metal in direct contact with the welding wire is partially melted, and the thermal conductivity of aluminum is very good. Defects are repaired after machining of aluminum castings without affecting dimensional accuracy. After repairing, the surface can be filed and polished or machined, and the appearance can be consistent with the base.
