Abstract: The copper clad aluminum wire is a "replacement" product of the inner conductor of the pure copper wire of CATV coaxial cable. This article describes the specifications of copper clad aluminum wire and the requirements for the quality and performance of copper clad aluminum wire. The characteristics of the copper clad aluminum wire produced by the domestic welding method are introduced, and the coaxial cable made of domestic steel ladle aluminum wire is introduced. The characteristics. ã€Key Feed】CATV Coaxial Cable Copper Clad Aluminum Wire Cladding Welding Method The copper clad aluminum wire is a bimetallic composite wire that concentrically covers the copper layer on the lead core and forms a metal-bonded interface between copper and aluminum. It is the "replacement" product of the CATV coaxial cable pure copper wire inner conductor, which has the advantages of rational use of natural resources, stable transmission of television signals, reduction of cable production costs, and ease of network engineering construction. CATV cables in the United States used copper-clad aluminum wire as early as the 1970s. In recent years, due to the advent of domestic copper clad aluminum wire, CATV cables such as 75-9, 75-12, and 540 produced in China have also begun to use copper clad aluminum wire as internal conductors. With the rapid development of China's information industry, cable television networks will continue to be built or updated, and a three-in-one network of cable television, telephone and computer will be developed. The use of coaxial cables with copper clad aluminum wire will have broad application prospects. Therefore, this article mainly introduces the relevant knowledge of copper clad aluminum wire, the characteristics of domestic copper clad aluminum wire, and the characteristics of coaxial cable with copper clad aluminum wire as the inner conductor, for reference by network construction personnel. 1 Copper Clad Aluminum Specifications and Their Quality and Performance Requirements 1.1 Copper Clad Aluminum Specifications The copper clad aluminum wire is divided into two types according to the volume ratio of the copper layer (the ratio of the volume of the copper layer to the volume of the copper clad aluminum wire): the volume ratio of the copper layer is 10% in the range of 8 to 12% (abbreviated as 10). The volume ratio of the copper layer in the range of 13 to 17% is 15% (15 in short). The copper clad aluminum wire is divided into two kinds according to the different hard and soft states: the unfired ones after drawing are in a hard state (indicated by H); and the annealed ones after drawing are in a soft state (indicated by A). Therefore, copper clad aluminum wire can be divided into four categories: 10H, 10A, 15H and 15A. Various types of copper clad aluminum wire can be drawn into different nominal diameters. The copper clad aluminum wire is denoted by code name CCA (Copper Clad Aluminum). Its specification is: For example, for a soft copper-clad aluminum wire with a diameter of 2.77 and a copper layer volume ratio of 15%, its specification is marked: CCA-15A-2.77. 1.2 The quality of copper clad aluminum wire (1) The copper layer thickness should be evenly distributed along the circumference. The standard stipulates that the copper layer is thinner in the circumferential direction. For 10A and 10H copper clad aluminum wire, it should not be 3.5% of the diameter of the small dry wire. For 15A and 15H, it should not be less than 5% of the wire radius, otherwise it will affect the TV signal. transmission. (2) The copper layer should have good adhesion to ensure no cracking during use. It is desirable to use a copper-clad aluminum wire clamped at both ends at a diameter of 15 times, twist it three times in the forward direction and then reverse three times in the reverse direction to check. (3) The interatomic bonds between the copper layer and the aluminum core should be formed, that is, they have better copper-aluminum adhesion. Generally, the copper clad aluminum wire can be bent off by any method and observed to be broken and checked. If the copper and aluminum layers on the fractures show that they are not bonded well. 1.3 To the performance of copper clad aluminum wire (1) Requirements for tensile strength and elongation. The tensile strength and elongation of hard and soft copper-clad aluminum wires of different diameters have different requirements, which have clear numerical rules in foreign countries and China's copper clad aluminum wire standards. Generally, the hard copper-clad aluminum wire has higher tensile strength and lower elongation. In the soft state, the tensile strength is lower and the elongation is higher. The selection of hard and soft states depends mainly on the cable manufacturer's cabling requirements. (2) Requirements for DC resistivity. The DC resistivity depends on the quality of Tong Village, copper thickness, copper-aluminum adhesion, and softening annealing process, reflecting the copper cladding aluminum wire material and processing technology level. 2 The main industrial production mode of copper clad aluminum wire and the characteristics of its products 2.1 Industrial production mode of copper-colored aluminum wire There are mainly three types of industrial production modes for copper clad aluminum wire. (1) Aluminum wire copper plating method. It is a method of electroplating a copper layer on the surface of an aluminum core wire to obtain a copper clad aluminum wire. This method is relatively simple, but the composition of the copper plating layer is impure and its performance is brittle. The copper plating layer and the aluminum core wire are often different, and it is difficult to meet the production and use requirements of the coaxial cable. At present, China is no longer producing. (2) Roller crimping method. The two copper strips that have been cleaned and heated cover the aluminum core wire from both the upper and lower directions, and the copper strip and the aluminum core wire are crimped together using the strong pressure of the roll. The two lugs of the copper tape seam are then cut off to form a line. The wire is then drawn to obtain the desired diameter and the desired properties are imparted by the heat treatment. This kind of process is more complicated, and the investment in rolling equipment is relatively large. As the welding equipment is covered, the cleaned copper strip is gradually formed into a circular tube, wrapped around the cleaned aluminum core wire, and the longitudinal seam of the copper tube is welded by argon arc welding. Continuously welding to form the wire blank. Then by pulling and heat treatment to obtain the desired diameter and performance. This process mode is relatively simple, the equipment is less complicated and the investment is less. The quality of the copper clad aluminum wire produced is better, which is currently the main production method in China. The coating welding device used in this method has obtained national patent. Datongfafa New Material Development Co., Ltd. will industrialize and commercialize the innovative technology of the production of copper-clad aluminum wire by the cladding and welding method, which has filled the domestic gap. 2.2 Characteristics of copper-colored aluminum wire produced by color-coating welding The copper-clad aluminum wire produced by the Tongfa Company using the cladding welding method is taken as an example to introduce its quality and performance. (1) The structure of the copper clad aluminum wire. The distribution of the copper layer in the circumferential direction is very uniform. Therefore, the copper layer and the aluminum core wire have better concentricity. (2) Metallurgical bonding of copper and aluminum interfaces. Due to thorough cleaning and strict protection measures for the copper tape and the aluminum core wire before the cladding welding, there is no black non-metallic inclusion on the boundary between the copper layer and the wrong core wire, which is a bond between the two metal atoms. Together created the conditions. When the finished product is bent or broken off, the delamination of the coating cannot be seen from the fracture. (3) The performance of copper clad aluminum wire. The mechanical properties (tensile strength and elongation) and direct current resistivity of the copper-clad aluminum wire through the inspection results of the Electronic Industry Information Transmission Line Quality Supervision Testing Center are listed in Table 1. US ATMM B 566-93 is also given in the table. The requirements for the mechanical properties and DC resistivity of copper-clad aluminum wire in the "Standard Specification for Copper-clad Aluminum Wire" and the "China Copper Clad Aluminum Wire" (approved for approval) in China's electronic industry standard are compared for comparison. The annealing process has a great influence on the mechanical properties and electrical resistivity of the soft copper-clad aluminum wire. During the annealing process, the copper clad aluminum wire forms a white bright metal compound (CuA12) layer on the copper and aluminum border due to heating. This The compound layer is very brittle. When its thickness is large, it will reduce the elongation and conductivity of the silver-clad aluminum wire. From practical considerations, if the annealing process is appropriate and the thickness of the compound layer is small, the performance of the copper clad aluminum wire will not be adversely affected. 3 Characteristics of coaxial cable with ladle aluminum wire as inner conductor Zhuhai Hansheng Special Wire Co., Ltd. adopts copper clad aluminum wire imported from the United States and copper clad aluminum wire 10 from Datong Communication Development Co., Ltd. to make a 12C-FT/A coaxial cable, which has passed the quality supervision, inspection and test center of the CATV system of the State Administration of Radio Film and Television. The tests were conducted according to the requirements of the industry standard GY/T135-1998 promulgated by the State Administration of Radio Film and Television. The test results are in favor of Table 2. Type Tensile Strength (Mpa) Elongation (%) Resistivity (Ω·m2/m) Standard Requirements Measured Value Standard Requirements Measured Value Standard Required Measured Value CCA-15A-3.76 ≤ 138 113.3 ≥15 37.5 0.02676 0.02578 CCA-15H -3.50 ≥172 210.0 ≥1.0 3.2 0.02538 CCA-15A-2.77 ≤138 125.0 ≥15 33.2 0.02560 CCA-15H-2.77 ≥186 221.8 ≥1.0 3.8 0.02557 CCA-15A-2.15 ≤138 133.3 ≥15 24.1 0.02509 CCA-15H-2.15 ≥200 230.0 ≥1.0 3.4 0.02565 Test Project Unit Technical Requirements Test Results Copper Clad Aluminum Conductor Copper Clad Aluminum Conductor Continuity Continuity of Outer and Outer Conductors Qualified Resistance Characteristic Resistance Ω 75.0±3.0 2.6*103 2.3*103 Attenuation Constant dB/100m 5MHz ≤ 0.7 0.6 0.65 50MHz≤1.9 1.74 1.78 200MHz≤3.9 3.68 3.72 550MHz≤6.7 6.45 6.54 800MHz≤8.2 8.05 8.10 1000MHz≤9.5 9.07 9.22 Return Loss dB VHF≥20 32.5 25.7 UHF≥18 26.2 28.6 Core dielectric constant kV ≥1.240-60Hz , 1min pass qualified From the data in the table, the technical indicators of the coaxial cable with the copper clad aluminum wire as the inner conductor are all superior to those in the industry standard; the coaxial cable made of pass-through copper clad aluminum wire and copper used in the United States The same products made of aluminum wire are all qualified products. Each cable TV construction unit can use it with confidence. It must be pointed out that since the mechanical properties of the copper clad aluminum wire and the pure copper wire are not exactly the same, attention should be paid during the construction of the project, and the experience of using the copper clad aluminum wire cable should be accumulated, and the transition to the use of the copper clad aluminum wire cable should be laid down. basis.