Copper tubes are called the "blood vessels" of air conditioners. The quality of the "blood vessels" will directly determine the quality of the air conditioner. Therefore, the welding quality of copper pipes is also highly valued. Today we will share an article about the welding o

2025/04/1113:46:38 home 1684

Copper tube is called the "blood vessel" of air conditioners. The good or bad of the "blood vessels" will directly determine the quality of the air conditioner. Therefore, the welding quality of copper pipes is also highly valued. Today we will share an article about the welding of refrigeration air conditioning copper pipes.

1. Basic knowledge of air conditioning

1. First, let’s introduce the basic knowledge of air conditioning.

air conditioners are divided into indoor units ( evaporator ); outdoor units ( condenser ); refrigerant is circulated in indoor and outdoor units through compressor .

is the schematic diagram of air conditioner cooling and heating:

controls the flow direction of refrigerant through the conversion of four-way valve to complete the cooling and heating conversion.

. Principle of cooling system

The components in the air conditioner are connected by copper pipes and are completely sealed to form a pipeline. The pipeline is sealed with "refrigerant". The welding work is to weld the pipeline and not leak, so that the refrigerant flows in the pipeline and cannot be leaked. This can improve the quality of the air conditioner, reduce the manufacturing cost of the air conditioner, and reduce the impact on the environment.

Refrigeration: compressor → four-way valve → outdoor unit → indoor unit, so that the air-conditioning system can complete the refrigeration.

Heating: Compressor → Four-way valve → Indoor unit → Outdoor unit, so that the air conditioning system can complete the heating.

. The structure and function of various air conditioners:

. The function of each component:

Compressor: Make the refrigerant in a high temperature and high pressure state in the compressor so as to liquefy the refrigerant and circulate the refrigerant in the pipeline. The compressor must have compressor oil . The function of the compressor oil is to improve lubrication for the reciprocating movement of the compressor, reduce friction, and can play a cooling role.

filter: filter impurities and dry moisture.

heat exchanger : cooling refrigerant;

four-way valve: cooling and heating conversion;

pipeline system: refrigerant circulation pipeline;

valve plate: switch connected to indoor unit;

electronic expansion valve : controls the flow of refrigerant.

Key management projects to ensure the quality of the cooling system

2. Key points of welding

①Safety education

②Heating method

Welding torch ignition method and flame adjustment method

Heating copper tubes until it can be visually judged that the tube color has reached 740-840℃.

actually experience the temperature of the melting of the copper tube (the appearance of holes). (1038℃)

is maintained for 10 seconds in welding temperature (740~840℃).

③Soldering method

Use 1.6mm×0% solder

Soldering position (opposite to heating method)

Time to add solder

Soldering dripping phenomenon (dripping caused by temperature difference)

④Soldering practical skills (outside the production line)

⑤Soldering practical skills (inside the production line)

First practice with 4.95mm and 4.76mm copper pipe parts.

is started with 1/2 units, and then gradually increase the frequency later.

should not be guided in the processing state, but should be guided by temperature.

Welding rod type:

html ml20%

Welding rod type

Ag content

BCUP-3

BCUP5

BCUP6

BAg30CuZn

The function of flux :

, thermal stability

, wetting

, cleaning

, isolate air, prevent re-oxidation, and do not produce slag inclusions. Types of

flames:

neutral flame: oxygen and acetylene volume ratio is between 1 and 1.2; copper.

Carbonization flame: the volume ratio of oxygen to acetylene is <1;>

oxidation flame: the volume ratio of oxygen to acetylene is >1.2 Iron and iron welding

The main causes of leakage during welding

3. Welding practical

For the welding practical steps, let's make a summary:

. Prepare welding gas, set Preparation and materials;

. Wear protective supplies;

. Check the status of welding equipment and tools;

. Open the bottle valve and adjust the oxygen pressure reducer to control the outlet pressure to 0.15~0.2MPa, and adjust the acetylene pressure reducer to control the outlet pressure to 0.01~0.02MPa;

. Open the acetylene regulating valve-ignition-adjust the acetylene regulating valve to make the flame length moderate;

. Open the oxygen pressure regulator- Slow withering makes the flame neutral flame;

. Use the flame in the order of neutral flame (small) → add acetylene → increase the feather flame → add oxygen → adjust to neutral flame (large);

. Use the flame in the order of neutral flame (large) → reduce oxygen → appear feather flame → reduce acetylene → wither to neutral flame (small) ;

. Make the tip of the flame heart 2~4mm away from the weld, perpendicular to the tube, and heat the full length of the weld evenly to red;

10. Apply flux . When the flux becomes a transparent liquid and evenly soaks the weld, send the solder coated with the flux to heat until the solder melts fully and fills the weld;

1. Remove the flame and keep the welds from being misaligned with each other before the solder solidifies completely;

2. Turn off the acetylene valve, then turn off the oxygen valve;

3. Loosen the pressure reducer and close the bottle valve;

4. Organize tools and equipment, and clean the site.

4. Welding quality check

check whether the sealing at the welding is good. After adding refrigerant or nitrogen gas for a certain period of time, you can use soapy water or other methods to ensure that there is absolutely no leakage in the welding area. After welding, necessary inspections should be carried out.

When the refrigeration and air conditioner is running, the welding area cannot be cracked (slit) due to vibration. The pipeline should not enter debris and be blocked during welding, nor should it enter moisture if it is improperly operated. When the refrigeration and air conditioning is working, the surface of the welding part should be clean and free of oil and stains.