Air-conditioning is mainly composed of compressor, heat exchanger and automatic control system. The copper tube in heat exchanger is called "blood vessel" of air-conditioning. The quality of air-conditioning will be directly determined by "blood vessel" , problems often occurred in the application of copper pipe in air conditioning. Copper tube is an important raw material for manufacturing refrigeration unit. It has two main uses: 1. Making heat exchanger. It is an important part of evaporator and condenser of air conditioning. 2. Make connecting pipes and fittings. Either way, it serves as a channel for the refrigerant, which is very important. In the application process, on the one hand, we require copper pipe production enterprises to provide high-quality copper pipe, on the other hand, we also require air conditioning refrigeration enterprises to properly use copper pipe.

Brief introduction of copper tube for air conditioner 011.1 process flow the manufacture of copper tube can be divided into two processes at present. ● Flow 1: Traditional extrusion process: Casting Foshan (cross-piercing) extrusion disk tension into coil annealing. : : Process 2: New Roll Casting Process:

NEW CAST rolling production process flow diagram 1.2 copper pipe external supply of several states copper coil: currently mainly used for the two main pipe, connecting pipe, pipe fittings. FEATURES: convenient transportation, user in the use of the process is not limited by the length.

MOSQUITO COIL: mainly used in maintenance market. Features: Easy to use. STRAIGHT PIPE: mainly used for central air conditioning, connecting pipe. Features: Transport Inconvenience, the use of the length of the limitations. Copper Tube leak copper tube leak is the fatal flaw of air conditioning, once the leak, all the refrigerant in the air conditioning will leak out, the air-conditioning unit lacks "blood" for heat transfer and is therefore ineffective. The reasons for the leakage of copper pipe are more complex, the following reasons for frequent leakage to be described. ● MANUFACTURING REASONS 1 EDDY current inspection missed. GB stipulates that 100% eddy current testing must be carried out on copper tubes, and the diameter of the artificial defect (through hole) on the sample tubes used for checking the flaw detector is specified to ensure the sensitivity of Eddy current testing and to prevent over-standard defects from being missed. This requirement is fully guaranteed in regular large copper tube plants because the flaw detection is on line, and this on Line Eddy current detection ensures that all lengths of Tube; Pipe; Drinking Straw are Eddy current tested, which is 100% . Some copper pipe factory is not so, or not through eddy current testing, or with low-standard Eddy current testing instrument sampling. In this way, copper pipe there are over-standard defects missed detection or not detected, resulting in the use of air-conditioning users leak. The defects were detected by Eddy current testing, but the marks on the surface of the copper pipe were not made or were inaccurate and unclear. In the production process of copper pipe, the defects detected by Eddy current inspection require that the ink is used to cover the over-standard defects so that the users can get rid of the defective copper pipe in the process of use. However, due to the reasons such as insufficient adhesion of the ink, improper adjustment of the inkjet gun, incomplete drying and high temperature fading of the ink components, it is impossible to pick out the defects detected by Eddy current inspection. Once the defective copper pipe is used on the air conditioner, it will cause leakage. Reasons for user's use user uses copper pipe to make two-piece process flow: cut-bend-expand pipe-clean-weld-test pressure. 1. The defective tube detected by misuse of eddy current testing. Under the normal production condition of copper tubes, the eddy current testing of copper tubes not only marks the number of damage points on each coil of copper tubes, but also marks the damage points in black so that the users can identify and pick out the "black tube" in use. Air conditioning and refrigeration enterprises to operators, especially the new workers to explain clearly, in order to prevent this wound pipe installed on the air conditioning and refrigeration devices. We have found this problem many times in our customer service, some workers asked us about the black on this pipe, some are dissecting substandard products, it is precisely because of the "black pipe" installed on the product caused the air conditioning refrigeration device leakage. 2 processing problems. In the process of forming the two units, the air-conditioner supervisor should go through the steps of pipe bending, pipe expanding, expanding, welding, etc. . In the process of pipe bending, because the bending part has to go through local force, resulting in local over-stretching, resulting in cracking, crack and other problems, once filled with refrigerant, often occurs here refrigerant leakage.

After the copper tube passes through the fin, it is necessary to expand the tube on the tube expander. The Tube expander is divided into two types: vertical and horizontal. In the process of tube expansion, the outer diameter of the copper tube is in full contact with the heat sink of the aluminum foil. In the process of tube expansion, it is very easy to scratch the copper tube with the expansion head, resulting in penetrating injury and leakage of the copper tube. 3 leakage due to poor welding. In order to make the connection between copper pipe and aluminum foil with holes, a small elbow joint is needed. In the production process, a small elbow and a copper pipe are welded together with solder, when welding, because of the quality of solder, the copper tube mouth, the welding surface has the foreign body and so on the reason, causes the welding not to be real, forms the false welding, causes the refrigerant to leak. 2.2 The cracking of copper tube is mainly concentrated in the process of expanding and expanding. In the production of the two devices, copper tube expansion, expansion is a continuous process, often compound to a process complete. There are many reasons for the cracking of copper pipe, the main reasons are as follows: 1 the reasons for the quality of copper pipe itself. The quality of copper tube itself can be divided into external surface defects, internal surface scratches, internal surface oxidation and so on. When there is a deep scar on the outer surface of the Copper Tube, the outer surface of the copper tube can not bear the surface tension stress, what we see is a crack in the outer surface of the copper pipe. The cracking mechanism caused by the scratch on the inner surface of the copper tube is similar to that caused by the scratch on the outer surface. When there is oxidation on the inner surface of the copper tube, the friction force on the inner surface of the copper tube is not equal to that on the inner surface of the copper tube without oxidation, so the length of the lower pier of the copper tube of the same length is not the same, the length of the copper tube with small amount of lower pier is long when the tube is flared, resulting in the excessive flared and cracked. 2 reasons why users use it. Copper pipe in use, is often coil straightening, cutting length, cutting often used chip-free cutting. The surface of copper pipe is soft after heat treatment. When cutting without chip, when cutting knife is bad or cutting knife is too big, the copper pipe will have too big or too many burrs, which will form the flanging and hardening of the port, and cause the crack when expanding the port. A heat exchanger consists of a number of "U" tubes. The length of each "u" Tube and the length of the two ends of each "U" tube require very high consistency, the length of each "u" Tube and the length of the two ends of each "U" tube are too different (larger than 2mm) due to equipment or adjustment reasons, therefore, there will be excessive length of the copper tube due to excessive length of the port extension caused by excessive expansion and cracking. 2.3 Bend Crinkle, Broken Copper Bend Crinkle, broken occurred in the production of "U"-type pipe process, copper pipe in this process is often scrapped more. The causes of wrinkling and fracture of the elbow are shown in the table below.

Left: Outer wrinkle right: Inner wrinkle

The problem of Copper Elbow 03 in the process of copper pipe welding, if the operation is not appropriate, it is easy to produce such defects as virtual welding, melting and piercing, over-burning and burning through, etc. . Virtual welding is a common quality problem in the welding process of the two devices. The main causes are: ● small expansion, brazing solder is not easy to enter, resulting in weak welding; ● uneven heating during welding, some brazed solder is not completely melted by heating, there are oil, oxide, carbon residue on the surface of the copper pipe at the welding point, and the quality problem of the solder itself. Causes the solder not to fill the socket joint full length or can not completely weld the socket joint full length, causes the leakage. Corrosion and penetration caused the leak. In a word, there are many factors that cause the failure of copper pipe, such as inner and outer surface oxidation, so we should strengthen the process control and master the process requirements. Classification of common copper tubes 04 COPPER TUBES:

The copper content is over 99.90% . It has good properties of copper metal, which is a high quality base metal. It is widely used in industry and civil fields, and plays an important role. There are three main types of TP2, T2 and TU1. TP2 is dephosphorized copper, containing 0.015-0.04% phosphorus, with good welding and cold bending properties. It is widely used in the manufacture fields of air conditioning and refrigeration connecting pipe, stove gas connection pipe, electric heating pipe and so on. T2 is pure copper, the copper content is higher than 99.90% , when the customer has the high electric conductivity request to the material, the T2 copper tube will be the first choice. TU1 is oxygen-free copper, copper content ≥99.97% , oxygen and impurity content very low, high purity, excellent conductivity, thermal conductivity, good ductility, processing performance and welding, corrosion resistance, cold resistance are good. Because of the high demand and high cost of its production, the price of its products is much higher than other categories of copper pipe. BRASS: copper-zinc Alloy Tube, the number after the letter h in the brand often represents its copper content of the middle value, zinc content for the remaining amount. Brass tubes of different brands, with higher and higher copper content, generally show better quality and extensibility. The utility model is mainly used as a water pipe and a connecting piece for wading. FEATURES: Copper Pipe with strong, corrosion-resistant characteristics, light weight, good thermal conductivity, low-temperature strength, can be used in a variety of environments.

 Source: Web Collation

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