Armoured cables

Rail transit with the problems in the production of cable and the solution measures

by:AAA     2020-04-23
( Industry news] Rail transit with the problems in the production of cable and rail transit construction solutions SXXLJT P China to speed up the pace, the increase of railway operation mileage, expansion and drive demand for rail transit cable, wire and cable of the demand is higher. Due to the particularity of rail transit construction, security, environmental protection of wire and cable products technology put forward higher requirements, such as wire and cable products in addition to having excellent electrical properties and insulating properties, but also must have a good flame retardant performance, water resistance and rat ant performance, so the product compared with the traditional power cable in material selection and process routes have new updates. Here's products are liable to occur in the production process of the problems and solutions is introduced. Rail transit with the power cable in the main problems in the process of producing insulation eccentricity, comprehensive protection layer of uneven and spark breakdown rate is high; Low smoke zero halogen flame retardant polyolefin material surface is not smooth, such as porosity. After repeated analysis and experiments that the causes of these problems are mainly the following several aspects: one, the three-tier co-extrusion insulation eccentricity. Because the thickness of the insulation is thick, insulating and conductor interface is smaller, so under the condition of high temperature and high pressure in the crosslinking tube, plastic sticky flow, will there is a certain degree of prolapse, so it is easy to appear the phenomenon of eccentricity is unqualified. Second, the comprehensive protection layer of uneven and high electric spark breakdown rate. The main cause of the problem: ( ) Is applied to longitudinally wrap aluminous model with shape when the force is not uniform, causing longitudinal package wrinkle appearance; ( ) Lu: su composite belt longitudinal packages, take the interface not glue cause cock; ( ) Lu: su flanging belt; ( ) Low smoke zero halogen flame retardant polyolefin material foam, punch, etc; Three, low smoke zero halogen flame retardant polyolefin material surface is not smooth and has a hole. The main cause of the problem: ( ) Raw materials stored improperly, lead to be affected with damp be affected with damp; ( ) Due to the material processing temperature is low, foam extrusion temperature too high can lead to material; ( ) Due to the high flame retardant, raw materials more filling agent is added in, cause easily when it is squeezed appearance is not smooth, crack, etc. Four, solving measures. Against the main problems appeared in the course of trial production, the technology of the guangdong southern line cable division of personnel, organization research procedure, procedure, and follow up implementation. By analysis the following solutions, used to achieve the expected effect, better meet the requirement of customers. ( ) For three layers co-extrusion insulation eccentricity problem solution is: when the crosslinking polyethylene plastic viscous flow in the crosslinking tube, we use the dow lower degree of KV crosslinked insulating material, in order to increase the viscosity of plastic itself, thus reducing the material under the high temperature molten state of prolapse, also on three-layer coextrusion equipment with online test instrument, ensure real-time monitoring, and finally, in a timely manner after the insulation wire core cooling roundness slice observation, in this way, products insulation performance and eccentricity are effectively controlled, fully meet the requirements of changsha metro eccentricity within %. ( ) For comprehensive protection layer of uneven and spark breakdown rate high problem solving measures are: the phenomenon is mainly due to the cable core diameter is larger, the aluminium with vertical bag forming caused by non-uniform of deformation and stress is applied to longitudinally wrap the strip after not level off, the first is lu: su composite with longitudinal bag mold, from big to small, a total of two groups before and after must be strict inspection before production mold size, prevent mold caused by large aluminous model with molding difficult; If lu: su from deformation to shaping during production, not in the same level, can appear wrinkling, inequality, then to timely adjust the position of the mold before and after to make sure that lu: su with flat; Lu: su with flanging is aluminous model with motorized and forming mold unaligned, need fixed on the floor of the motorized strictly; For aluminous model with a mouth not glue, timely adjust position and temperature of the heat gun, can better solve the problem; ( ) For low smoke zero halogen flame retardant polyolefin material surface is not smooth, foaming, perforation of the pores, problem solving measures are: one is the fight in the rubber impurities mixed with; Check whether the breakage of the package materials into the factory, found that damage to timely cleaning; 2 it is to make plastic moistureproof, if the weather is wet, plastic should be at least hours before extruded drying process; Three is to improve extrusion mould, we found in production, low smoke zero halogen flame retardant polyolefin material using ordinary mould surface is not smooth, the analysis considered working face of die set, plastic tensile stress is bigger, so we have designed reduce the die set of working face is special mould, and USES the water tank from high to low temperatures segmented cooling method to eliminate internal stress; Four is with low compression screw, reduce screw shear heat; Fifth, control of draw ratio, keep on. The following, reduce the risk of sheath extruded degumming. After trial production, the exterior problems effectively; Finally, through the above measures, not only effectively solve the surface, foaming, porosity, breakdown, and other issues.
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