Copper Pipe Welding Technology

Copper pipe welding technology is the most important part, and it is an important guarantee whether the copper pipe can be successfully put into use in various industries.
The position of filler metal is about 2 mm above the nozzle, and the position of filler metal must be guaranteed in the front and back of the flame heating, so that the hot copper tube can melt the welding rod, and the solder can flow uniformly and spread on the surface of the gap.

After the feeding welding is completed, the flame is heated uniformly by swinging down the Z-shaped line until the added solder is fully penetrated into the weld; the function of the lower part of the heating pipe is to make the solder fully melt and penetrate.
After the “Z” word is used to heat downwards, then the “Z” word is used to heat upwards; while heating the upper pipe mouth, the solder is added at the same time until the solder is even and full. After the filling, the flame must be slowly drawn to 30-50 mm at the tip of the flame, and then stay for 2-3 seconds to heat the solder joint, and then remove the electrode. Complete the whole welding procedure.
Copper pipe welding technology needs to wrap sensors, four-way valves, expansion valves, check valves, needle valves and other components with wet cloth immersed in water; it requires that the moisture of wet cloth should not flow into components, pipelines and other systems; the surface of copper pipe oxidizes sharply at brazing temperature, in order to effectively reduce the production of oxide skin inside copper pipe, copper pipe should be treated. The pipe is protected by nitrogen charging. After the copper pipe is assembled, the copper pipe joint is filled with nitrogen. Nitrogen pressure is about 0.2 (relative pressure). Hand feel airflow. Nitrogen flow should not be too large, or there will be gas holes during welding, which will affect the welding quality. Nitrogen filling should be advanced 10 seconds before welding; Nitrogen filling should be delayed 10 seconds after welding; impurities and oil contamination should be cleaned up before welding, and alcohol can be used to assist cleaning.
When welding branch pipelines such as sensors, it is necessary to pre-install welding offline, and then weld them to the unit system; in order to avoid the flow of welding debris and other materials into the unit system; the welding joints near the condenser and other places need baffle protection; after welding, let the weldments cool naturally, and do not use low-temperature materials such as wet cloth to quickly weld the parts. Cooling; Nitrogen filling from the stop valve during welding on the whole machine.

Why should nitrogen be filled to protect the inner wall of copper pipe when brazing?
Because flame brazing is widely heated and accumulated in the heating process, the common metals will be oxidized when heated. Therefore, the welding joints will be heated during the welding process, which will lead to the internal heating of copper tubes, resulting in internal oxidation. Therefore, it is necessary to protect the inner wall of copper tubes by nitrogen filling.
Electronic expansion valve tube group is the key component of air conditioning system, which is related to the operation status of the whole unit. The electronic expansion valve is a very precise component, and its internal stepper motor and other components are very vulnerable to damage at high temperature, so the welding of the electronic expansion valve needs to do enough protection:
1. Immerse the whole water through the electronic expansion valve, pay attention to the water can not enter the pipeline.
2. Nitrogen filling protection from both ends during welding at the same time, in order to prevent the nitrogen filling from being heated to high temperature gas passing through the valve core and damaging the electronic expansion valve.
3. When welding the whole electronic expansion valve parts with heat exchanger, it is also necessary to protect the wet cloth of the electronic expansion valve package.
4. If the valve body is close to the solder joint, the valve body can be treated with water sprinkler on the basis of the wetting cloth.