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• Time of issue:2020-02-15
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(Summary description)The refractory layer uses a new material "ceramic siliconized rubber", which is a new type of polymer composite material. In the case of flame ablation at 750 ℃ ​​× 90min, it will not be burned into powdery ash, which can form a hard ceramic shell, which plays the role of insulation and fire protection. And the higher the temperature, the longer the burning time, and the harder the shell. This material is used as a cable refractory layer and can withstand certain spray and impact effects. And has excellent electrical properties, good mechanical properties and other characteristics, according to the special process performance of materials, we determined to trial production on φ85 silicone rubber extruder. During the trial production process, we found through multiple tests that the tensile strength and elongation at break of its physical and mechanical properties always failed. Therefore, in the trial production, we adjusted its key operations multiple times, and after repeated debugging and testing, we finally succeeded. The fireproof layer extrusion process is as follows:

1. Cold extrusion should be adopted. The temperature of the screw, head and fuselage of the extruder should be lower than 30 ° C, and the highest temperature should not exceed 50 ° C. The lower the cooling water temperature is, the better; Sulfur, clogging the head;

2. The electric heating oven or oven is according to the first stage temperature: 160 ～ 180 ℃, the second stage temperature is 165 ～ 185 ℃, the third stage temperature is 170 ～ 175 ℃, the fourth stage temperature is 175 ～ 180 ℃, and the last stage The temperature is set and heated at 200 ～ 230 ℃, and the vulcanization temperature of each section can be set according to different models of equipment and cables of different structures. The principle is that there are no micropores in the cross section of the product, and there is no air bubble in the longitudinal direction of the wire and cable. First, the temperature of the first and second stages should be lowered by 5 to 10 ° C, and the temperature should be gradually lowered by 5 to 10 ° C until no bubbles are generated;

3. Production speed is a key parameter that directly affects the degree of vulcanization. According to vulcanization curve data, after repeated verification, it is determined that it is about 10m / min. It is necessary to slow down at the beginning of extrusion and then increase the speed slowly. It can guarantee qualified physical and mechanical properties.

4. The cable extruded by extrusion die has good appearance quality, smooth and round surface. According to the properties of the ceramic silicon rubber material, after repeated tests, it was finally decided to use extrusion mold production. The length of the mold section molding section is shorter than ordinary rubber. The length of the molding section is recommended. The length of the molding section of the small cross section is 1.5-3mm. The length of the shaping section is 2-5mm.

5. Mold polishing. In order to improve the appearance quality of the cable extrusion, the ceramic silicon rubber mold must be polished before extrusion. If the extrusion surface is rough and not smooth after polishing, adjust the distance between the extrusion die sleeve and the die core. At the same time, the extruded material should be slightly larger than the diameter of the finished wire, and the die sleeve should be slightly smaller than the ordinary silicone rubber wire and cable. Some, in the end, are subject to actual production site commissioning.

(Southern Cable Network)