With the development of society, users have higher requirements for multimedia transmission such as graphics, text, audio, video, and data. As a high-frequency transmission medium in the wiring system of intelligent buildings and residential areas, LAN cables have higher and higher requirements in engineering, especially for the production process requirements of LAN cables. How to avoid various problems in the production process and produce LAN cables that meet the requirements? Read the LAN cable production FAQ manual!
1. Tandem process
The tandem line is a process that plays a decisive role in the entire production process. Therefore, the control accuracy of the tandem process directly determines the various indicators of the LAN cable.
Generally, the tolerance of the conductor is controlled within ±0.002mm. It is necessary to ensure that the conductor is free of burrs, smooth and round, and free of oxidation. After the conductor is stretched by the wire drawing die, the elongation of the conductor should be between 18% and 24%. After the conductor extruding insulation layer, it is necessary to ensure that the tolerance control range of the outer diameter of the insulation is within ±0.005mm, and the eccentricity of the single wire is controlled above 95%, and the insulation elongation should be greater than 300% after stretching, there can be no elongation too small or no elongation.
Problems that are prone to occur in the series process:
① Wire broken is the most serious problem in the tandem production line process. The reasons are:
1). Copper wire is hollow or has impurities
2). The wire drawing die is broken or the die ratio is improper
3). The concentration of the soap solution in the wire drawing machine is wrong, or the flow rate of the soap solution is small
4). The traction of the wire drawing machine is unstable
5). Improper number of turns of copper wire winding
6). The annealed nickel ring is broken or the surface of the annealed pulley hot ring is not smooth
7). The temperature of annealing water is too high or the temperature of annealing and preheating is too high
② Conductor eccentricity will occur during the production process.
After the conductor is fed with current, the insulation layer will be broken down at the link where the conductor has a large eccentricity. In addition to the reason for the installation of the core and mold sleeve, it should also be checked whether the wire is under the sink plate and cannot be cooled by water, otherwise it will cause eccentricity. It can also cause instability in the outer diameter. The production process will show that the outer diameter is normal, and the capacitance and conductor become smaller. When changing the color or adding color masterbatch, the concentration of the color masterbatch will affect the capacitance of the conductor. The greater the concentration of the color masterbatch, the greater the capacitance, and the color The proportion control of the masterbatch can be adjusted according to the brightness and transparency of the masterbatch, generally controlled between 1% and 1.2%.
③ Oxidation of copper wire is also one of the most serious problems in the tandem production process.
The main cause of copper wire oxidation is that the annealing or preheating temperature is too high. It is also necessary to check whether the annealing water is too little or the annealing water contains soap. The concentration of the soap should not be too high, and is generally controlled at 5% to 6%. Whether there is a problem of poor sealing inside the annealing furnace, and check whether the drying equipment is not well ventilated, etc.
2. Twisting process
The twisting process is to twist two single wires together at a certain pitch, and two points should be controlled: the pitch and the tension of the take-up and pay-off. The pitch and the tension of the take-up and pay-off mainly control the attenuation, crosstalk, return loss, impedance and other indicators. During production, it is necessary to ensure that the pitch is stable and the tension of the take-up and pay-off frame must be consistent. Otherwise, the pitch fluctuation range will be large, the thickness of the conductor is uneven, which affects the propagation of the speed and causes amplitude distortion.
The problems often occur during the twisting process:
①Twisted wires often have rough surfaces. Before starting the machine, check whether the single wire is in the guide. If it is not in the guide, it will easily get scratched and damage the insulation layer structure;
②The pitch of the twisted pairs is disordered. Before starting the machine, check whether the gear used is correct. If the gear is used incorrectly, the pitch deviation will be large;
③The insulation resistance of twisted pair wires with joints often has unsatisfactory conditions. During cold rolling, the joints should be as smooth as possible. If there are cold-rolled burrs, the casing on the surface will be punctured; Staggering a certain distance, and the two connectors being too close may also cause poor insulation resistance.
3. Cabling process
The cabling process is roughly the same as the twisting process. Four sets of twisted wires or multiple pairs of twisted wires are arranged and produced according to a certain pitch and color sequence. The tension and pitch must be strictly controlled. When making oil-filled cables, the temperature of the oil must be controlled. If the temperature is too high, the insulation layer of the conductor will be scalded. Secondly, when producing oil-filled cables and outdoor cables, polyester tape and binding yarn must be added. The tension of the polyester tape and the wrapping speed of the binding yarn must be controlled well, otherwise stripping or lumps may occur during the sheathing process.
4. Sheathing process
The sheathing process is the same as the series process, which is a key special process. During the production process of the sheath, the temperature must be controlled according to the process. If the temperature is too high, the extruded material has a high viscosity, and the surface of the sheath is frosted; If it is too low, the material will break easily and become dull.
During this process, the following questions often arise:
① During the sheathing production process, scratches or peeling off the surface of the product most often occur. The main reasons for the above are:
1). First, determine whether the sheathing material is mixed with gravel or impurities;
2). Whether the shutdown time is too long. Long-term shutdown will cause burnt material to be produced at the outlet of the machine head. Whether the inside of the screw of the machine head is clean. If there are impurities left, scratches will be produced on the surface of the sheath in mild cases. In severe cases, it will cause scratches on the surface of the sheath. Material will come off;
3). The mold sleeve is not round and has unevenness or defects. If it is not round, it will be bent and flat, and it will also cause uneven wall thickness;
4). The linear speed is too fast and the screw speed is small;
5). Because outdoor cables and oil-filled cables need to be covered with polyester tape when forming the cable. If the polyester tape is not wrapped tightly, the sheathing material at the machine head cannot be completely protected on the cable, resulting in stripping. This phenomenon is more obvious in large logarithms;
6). The probability of shielding wire stripping is small, but the tension of the aluminum foil must be controlled well. If the aluminum foil is not wrapped well, the surface of the sheath will be uneven, and in severe cases, there will be holes on the surface of the sheath.
② When bulging occurs in the sheath, the non-shielded wire is more likely to appear. There are several reasons:
1). The thickness of the sheath is too thick;
2). When the cable is started and shut down, the yarn binding speed is not well controlled, resulting in the accumulation and congestion of the yarn binding. Of course, the cause of the material cannot be ruled out.