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With the development of society, users are increasingly demanding multimedia transmissions such as teletext video and data. Data cables are used as a high-frequency transmission medium in intelligent building and residential wiring systems. The requirements for data cables in engineering are getting higher and higher, especially the production process requirements for data cables. How to avoid problems in various production processes and produce data cables that meet the requirements? Read the data cable production FAQ manual!
Frequent problems in the production of data cables.
1, tandem process
The serial line process is a process that plays a decisive role in the entire production process. Therefore, the accuracy of the serial process control directly determines the various indicators of the cable.
The tolerance of general conductor is controlled within ±0.002mm. To ensure that the conductor is free of burrs, smooth and round, and no oxidation, after the conductor is stretched through the drawing die, the elongation of the conductor should be between 18% and 24%. Hard wire phenomenon occurs; after extruded insulation of the conductor, ensure that the tolerance of the outer diameter of the insulation is within ±0.005mm, and the eccentricity of the single wire is controlled above 95%. The tensile elongation of the insulation after stretching should be greater than 300. %, there is no case where the elongation is too small or there is no elongation.
The following problems often occur in the series process:
1 Broken wire is the most serious problem in the serial production process. The causes of wire breakage are:
1). Copper hollow or impurities;
2). Bad drawing die or improper mold ratio;
3). Drawing machine soap concentration is not right, or soap flow is small;
4). Drawing machine instability
5). The amount of winding of the copper wire is improper;
6). Annealed nickel ring is broken or the surface of the annealed pulley hot ring is not smooth;
7). Annealing water temperature is too high or annealing, preheating temperature is too high
2 Conductor eccentricity may occur during production.
After the conductor is connected to the current, the insulation layer will be broken at the large eccentricity of the conductor. In addition to the reasons for the installation of the mold core mold, it is also required to check whether the wire is under the sink plate and not be cooled by the water, in addition to causing eccentricity. Outside also causes instability of the outer diameter. The production process will show that the outside diameter is normal, and the capacitance and the conductor will become smaller. When the color is changed or the color masterbatch is added, the concentration of the color masterbatch will affect the capacitance of the conductor. The greater the concentration of the color masterbatch, the larger the capacitance and the color. Masterbatch ratio control can be adjusted according to the masterbatch brightness and transparency, generally controlled between 1% and 1.2%.
3 Copper oxidation is also one of the most serious problems in the tandem process.
Caused by the oxidation of copper wire is mainly because the temperature of annealing or preheating is too high. At the same time, it is also necessary to check whether the annealing water is too little or the bath water contains soap liquid. The concentration of the soap liquid should not be too large, generally controlled at 5% to 6%. The inside of the annealing furnace has a problem of poor sealability, and at the same time, it is checked whether the blow-drying equipment is poorly ventilated or not.
2, twisting process
The twisting process is to twist two single wires together at a certain pitch. In the twisting pair, two points should be controlled: the pitch and the tension of the take-up and release line. Pitch and pay-off line tension mainly control attenuation, cross-talk, return loss, impedance and other indicators. During production, it is necessary to ensure that the pitch size is stable and the tension of the retractable wire rack must be the same. Otherwise, the pitch fluctuation range will be large. The uneven thickness of the conductor affects the propagation of the velocity and causes distortion of the amplitude.
The following problems often occur in the twisting process:
1 The surface of the twisted pair often appears rough. Before starting the machine, it is necessary to check whether the single wire is in the guide wheel. It is not easy to wipe the hair in the guide wheel and destroy the insulating layer structure.
2 The twist-to-line pitch is disordered. Before starting the machine, check whether the used gear is correct. If the gear is used incorrectly, the pitch deviation is large.
3 The twisted pairs of joints often have unsatisfactory insulation resistance. When cold rolling, joints should be as smooth as possible. If cold rolling burrs are left, the surface of the casing will be punctured; Staggering a distance, too close to two joints may also result in poor insulation resistance.
3, cable process
The cable forming process is almost the same as the twisting process. Four pairs of twisted pairs or multiple pairs of twisted pairs are arranged according to a certain pitch and color sequence. The tension and pitch must be strictly controlled. In the case of oil-filled cables, the temperature of the oil must be controlled. If the temperature is too high, the insulating layer of the conductor will be burnt. Secondly, in the production of oil-filled cables and outdoor cables, polyester belts and yarns must be added. The tension of the polyester belts and the winding speed of the yarns must be controlled. Otherwise, the material will be stripped or have a knob in the sheathing process. phenomenon.
4, sheathing process
The sheathing process is the same as the in-line process and is a key special process. During the production process of the sheath, the temperature must be controlled according to the process, the temperature is too high, the viscosity of the extruded material is large, and the surface of the sheath is frosted; if the temperature Too low, the material is easily broken and dull.
In the process, the following questions often appear:
1 In the production process of the sheath, the surface of the product is often scratched or missing. The main causes are as follows:
1). First of all, to determine whether the sheath material mixed with sand or impurities;
2). whether the downtime is too long, a long shutdown will lead to the head of the outlet there is a coke production, the head screw is clean, if there are impurities, light will cause scratches on the jacket surface, when serious Will remove material;
3). The mold sleeve is not round and has irregularities or defects. If it is not round, there will be flattening and uneven wall thickness.
4). Line speed is too fast and screw speed is small;
5). Because the outdoor cable and the oil-filled cable need to be covered with polyester tape when it is cabled, if the polyester tape does not cover tightly, the jacket material at the head cannot be fully protected on the cable, resulting in material loss. The phenomenon of large logarithm is more obvious;
6). Shielding wire has a low probability of stripping, but the shielded wire should control the tension of the aluminum foil. If the aluminum foil is coated badly, the surface of the sheath will not be even. In severe cases, there will be holes on the surface of the sheath.
2 The bulging phenomenon occurs in the sheath. The probability of non-shielded wires is high. There are several reasons:
1). Jacket wall thickness is too thick;
2) When the cable is turned on and off, there is no control over the speed of the yarn, causing the yarn to gather and jam. Of course, the reason for the material cannot be excluded.