Screw sleeve(extruder parts)
The screw sleeve wrapped outside the screw can be made into an integral structure, but it is usually equipped with a jacket to be used for circulating heating of steam or superheated oil or cooling of circulating water. Its purpose is to enable the extruder to accurately adjust the temperature of each working section. Most screw sleeves are equipped with pressure sensors, temperature sensors and temperature control devices. The inner surface of the screw sleeve is usually made into a groove shape, some linear grooves and some spiral grooves. Spiral grooves produce boost downstream, while linear grooves hinder downstream. Therefore, the linear groove will lead to lower flow velocity, but its mechanical shear effect is greater. The clearance distance between the screw and its sleeve is usually kept to a minimum to reduce leakage flow.
Die head(extruder parts)
The end of the screw sleeve is usually equipped with a molded disc with holes of various shapes, which is generally called die head. The die head has dual functions: pressing the extruded material into the required shape; It is used as a choke to increase the pressure in the ripening section of the extruder. Determining the geometry of die hole plays a very important role in the shape and quality of extrusion products. A variety of hole forms of one-way die have been developed and applied, such as cylindrical hole die, slot hole die, annular hole die, and two-way die. The feed in the two-way molding die head comes from the discharge port of one-way molding of two extruders, which can be processed into extruded products with dual color or dual taste.