Preheating of the hot stamping extrusion line, cable preheating is necessary for both insulation extrusion and jacket extrusion. For the insulating layer, especially the thin layer insulation, the existence of the pores cannot be allowed, and the core can completely remove the moisture and oil on the surface by preheating before high temperature. For sheath extrusion, its main function is to dry the core to prevent the possibility of voids in the jacket due to moisture (or moisture surrounding the cushion).
The preheating of the hot stamping extrusion line also prevents the internal pressure of the plastic from being quenched during extrusion. In the process of squeezing plastic, preheating can eliminate the disparity temperature difference formed when the cold wire enters the high temperature machine head and contact with the plastic at the die mouth, avoiding the fluctuation of the plastic temperature and causing the fluctuation of the extrusion pressure, thereby stabilizing the extrusion amount and ensuring Extrusion quality. The electric heating core preheating device is used in the extrusion unit, which requires sufficient capacity and ensures rapid heating, so that the core preheating and core drying efficiency are high. The preheating temperature is limited by the speed of the line, and is generally similar to the temperature of the head.
The formed plastic extrusion layer of the hot stamping extrusion line should be cooled and set immediately after leaving the machine head, otherwise it will be deformed under the action of gravity. The cooling method is usually cooled by water and divided into quenching and slow cooling depending on the water temperature. Quenching is the direct cooling of cold water. Quenching is beneficial to the shaping of plastic extrusion coating. However, for crystalline polymer, due to the rapid cooling, it is easy to residual internal stress in the extrusion layer, resulting in cracks during use. The plastic layer is quenched.www.cnyudajixie.com