1. Welding of aluminum tubesThe use of high-frequency electric resistance welded steel pipe in China began in the 1950s. This process has been widely used, but the high-frequency power supply is used to weld the aluminum tube. Currently, it is still in the experimental stage. The foreign high-frequency welding aluminum tube started in 1955. In 1966, the number of high-frequency welded aluminum tubes in the United States reached about 50% of the total aluminum tubes. High-frequency welding of aluminum tubes, the welding speed is faster than the straight seam submerged arc welded pipe, the weld heat affected area is narrow, the weld quality is good, and the production efficiency is high. Therefore, in the industry of manufacturing aluminum tubes, this will be a development. Process.

Technical difficulties in the welding process of aluminum tubesa. Aluminum has a low melting point, high thermal conductivity, large heat capacity, and large thermal expansion coefficient.b. Aluminum and oxygen have a great affinity, and their oxides can cause inclusions in the weld.c. Aluminum can absorb a large amount of hydrogen when it is in a liquid state, so the welding of aluminum tends to generate pores.d. When the heating temperature of aluminum and its alloy reaches the melting point, the process proceeds from the solid state to the liquid state, and the process proceeds quickly, and there is no color change, so there is a certain difficulty in welding.2. Requirements for high frequency power supplyFor the technical difficulty of the aluminum tube welding process, the following requirements are imposed on the high frequency power supply:a. Use a higher frequency, so that the weld heat affected zone is narrow and the pipe inner wall current is reduced.b. The power density of the weld is required to be large, and the faster the welding speed, the better the weld quality.c. The anode voltage of the tube anode is required to be stable and smooth, and its pulsation coefficient is required to reach about 1%.3. Several measures adopted for welding aluminum tube high frequency power supplya. Use a higher frequency, 600 ~ 700KHz for 100KW equipment, 700 ~ 800KHz for 60KW equipment.b. The tube anode power supply adopts 12-phase rectification and is equipped with a smoothing filter. Because of the thyristor voltage regulation, it should be operated Butt fusion welding machines in a small conduction angle state to reduce the pulsation coefficient after rectification.c. has a higher output power, so that the aluminum tube has a higher welding speed.d. reasonable oscillation circuit, should be easy to adjust the load.4. Application prospectsAluminum has the characteristics of large reserves, high strength, light weight and corrosion resistance. Therefore, the welded aluminum tubes with large output and low cost are widely used in agricultural sprinkler irrigation systems, chemical, textile, light construction and furniture to replace steel pipes.. At present, domestic welding aluminum tubes are mostly argon-arc welded, the speed is very low, and high-frequency welding is used instead, which can achieve high speed.

The equipment manufactured by our company can achieve a welding speed of more than 120m/min for small-diameter thin-walled tubes. In addition, high-frequency welding can also be used to weld stainless steel pipes, copper pipes, brass pipes, etc., and non-magnetic metal pipes. This new technology is expected to attract the attention of the pipe manufacturing professional factory.2. Welding of copper and brass tubesIn 2001, we also succeeded in welding copper tubes and brass tubes with high-frequency power supplies. The welded tubes were tested by techniques such as pressing, reaming, and biasing, and were all qualified products.3. Welding of stainless steel pipeThe technology of welding stainless steel tubes with high-frequency power in foreign countries has been widely applied. We have not yet practiced it, and we are willing to cooperate with enterprises that need it to complete it.