Hot Feed Extrusion Process
(1) Refining and glue supply
In addition to the cold feeding extruder, the mixing and parking of the cooling rubber must be preheated before extrusion. The process of feeding machine is called hot smelting. The heating method and requirement are the same as that of calendering compound. The temperature and plasticity of the compound vary according to the formulation and process requirements, but the uniformity and stability of the temperature and plasticity of the compound are the same, which is the purpose of hot smelting.
Extrusion process includes selecting extruder, preheating equipment, adjusting die shape, controlling extruder temperature and extrusion speed, etc.
1. Selection of extruder type should be based on the specifications, properties and rubber properties of extruded products. Under the given conditions, the size of the die is the main factor to consider when selecting the equipment. !
The diameter of extruder screw should be in accordance with the size or width of the aperture. Under the condition of given aperture, too small size of extruder will lead to insufficient pressure at the die, which will affect extrusion and rubber density; too large size of extruder will lead to higher pressure in the die and easy to cause scorch. For circular die, the diameter of screw is generally 1.3-3 times of the diameter of die; for flat die (such as tread die), the maximum extrusion width is generally 2.5-3.5 times of the diameter of screw.