Nylon sheath of cable extrusion process
Nylon sheath of cable extrusion process
1, material drying: nylon material easy to absorb moisture can not be opened in the nylon material exposed in the air too long, and the poor thermal stability, easily oxidized at high temperatures. To prevent raw materials absorb moisture from the air, to ensure continuous and stable product quality, out of 70 ℃ in advance before drying for 2-4 hours, preferably by vacuum suction conveyor drying nylon materials for continuous production.
2, core Preheat: To ensure the nylon sheath and cable core insulation layer extruded dense to prevent the sheathing bend wrinkle, wire core nylon jacket should be carried out in the crowded online preheating, the preheating temperature can be controlled within 60 ~ 90 ℃.
3, Die Option: nylon extrusion is different from the extrusion of PVC, nylon, high melting point, melt flow is good, is conducive to forming high-strength thin-wall jacket, but must use a special mold. Matching in the mold, in order to adapt to the thin nylon jacket extrusion, nylon extrusion extrusion die used for extrusion and tube extrusion, mold core insulation diameter = OD + (1 mm ~ 2mm), die set diameter = punch diameter + 2 + 3 times the thickness times the modulus of nylon sheath thickness; out of the mold required before, sub-feeder such as a thorough clean-up, replace the filter, clear barrel, screw and die on the existence of residual glue, impurities and coke.
5, temperature control: temperature control requirements of the extrusion of nylon high body heating zone are to prevent the temperature is too high or too low nylon material. Temperature is too high, the material will turn yellow, thinning, not stretching, crystallization temperature is too low too early, causing the material difficulties, the extrusion temperature and extrusion speed is also affected by the amount of qualifying the impact of molten nylon, poor thermal stability, prone to degradation leaving sheath degradation, it does not allow the barrel at a high temperature nylon stay too long, nylon 6 melting point temperature is 280 ℃, so processing extruder temperature of each section can not be over the temperature.
6. Vacuum: In order to close sheath extruded, nylon sheath and remove the air between the PVC insulation to increase adhesion and reduce the nylon in the extrusion process by the tensile stress and improve the mechanical properties of the finished product, nylon Care sets used in the extrusion process method of vacuum, vacuum pressure to not to fall nylon material subject to different specifications of the product should be used in different vacuum pressures.
7. Cooling shaping: The sub-cooling means for cooling, air cooling which is about half a meter in length; the first paragraph of the cooling temperature of the cooling water tank 43 ~ 60 ℃, tank length of about 1 to 3.5 meters. This gradual cooling step, you can guarantee there is a good nylon crystal alignment, to prevent nylon by the sudden increase in cold and brittle and cracking, and eliminate the stress of nylon, and the second can be used for cooling water.| Updated:2010.11.28 Source: Clicks:7776
