EVCOME EV charging stations for better life---Top EV charging stations manufacturers & suppliers in China.
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EVCOME EV charging stations for better life---Top EV charging stations manufacturers & suppliers in China.
Wire and cable are industrial products that are inspected annually by the Market Supervision Administration. We often see such a situation: the thickness of the cable sheath is unqualified. How does an unacceptable specific sheath thickness affect the cable? What kind of sheath is qualified? How do we make qualified cables in production? Unqualified sheath thickness 1. Reduce the service life of wire and cable products This is easy to understand. After long-term operation, especially after direct burial, the insulation level and mechanical level of the thinnest point of the sheath will decrease due to long-term corrosion by external media, exposure to open air or corrosive environments, especially after direct burial. Coupled with regular sheath testing or line ground faults, the thinnest point can be broken down. In this way, the protective effect of the cable sheath is lost. In addition, internal consumption cannot be ignored. Long-term power on will generate a lot of heat. A little common sense is added here: the allowable operating temperature of the conductor is 70°C, and the temperature for long-term use of polyvinyl chloride should not exceed 65°C. So the wires and cables are actually“Internal and external troubles”situation. 2. Increased difficulty in the laying process With the development of global industry, more and more environments require high-voltage cable products to be small, and gaps need to be considered during laying to release heat from wires and cables, and the thickness of the sheath will increase It is difficult to lay, so the thickness of the sheath strictly complies with the relevant standards, otherwise it cannot play the role of protecting wires and cables. Nor can blindly pursue its thickness. What kind of sheath is considered qualified? According to the above two analysis, it is not difficult to see whether the product quality is good or bad. The first feature of the advantages and disadvantages is to reflect the appearance quality of the product. No matter what kind of product or semi-finished product, we must pay attention to the appearance quality in production, and strictly control and inspect it. The sheath is the appearance of the cable, which is required to be smooth and round, with uniform luster, no eccentricity (not exceeding the specified deviation), no mechanical damage, flattening, no visible debris, bubbles, trachoma, obvious particles, slub shape, twist shape, etc. In addition to the above quality requirements, the thickness of the sheath also has a certain impact on the quality of the cable. As we all know, the function of the cable sheath is to protect the insulated core of the cable from damage under the action of external force and play a protective role. If the thinnest point of the cable jacket does not meet the requirements, the cable jacket will be damaged before reaching the normal maximum external destructive force. If the thickness of the cable sheath in production is lower than the standard requirements, it is unqualified, and if the thickness exceeds the standard requirements, it is unqualified. For example: the cable model is DLD-KYJV223*1.5mm2, and the average thickness of the measured sheath thickness is 1.7mm. If this model refers to the requirements of the GB9330-88 standard, the thickness should be 1.2mm. Points to pay attention to in the production of the sheath 1. The calculation formula for controlling the thickness of the sheath is calculated according to the standard: D (outer diameter before extrusion)×0.035+12. On-line measurement of sheath thickness Sheath thickness = (perimeter after extrusion sheath - circumference before extrusion sheath) / 2πor sheath thickness = (perimeter after extrusion sheath - extrusion Circumference before sheath)×0.15923. Thinnest point of single core sheath: Nominal value:×85%-0.14. The thinnest point of the thinnest sheath: Nominal value:×85%-0.15. Increase the temperature of the low-density polyethylene sheath extruder to increase the stress cracking resistance, because the extrusion temperature is too high, it is easy to burn the plastic or appear“slippery”Phenomenon; in addition, the shape stability of the extruded layer is poor, the shrinkage rate increases, and even cause color changes and bubbles in the extruded plastic layer. 6. Do a good job of extruding body and screw cooling system to eliminate frictional overheating and maintain extrusion The heat balance in the process can stabilize the extrusion pressure, promote the uniform mixing of plastics, and improve the quality of plasticization. To sum up, in the production process, we can only carefully operate the equipment and strictly control the thickness of the sheath in accordance with the standard requirements, which can not only save resources for the enterprise, reduce material consumption, increase profits, but also ensure the quality of cables and create high-quality products. , Low-priced products. .
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