Production process control differences

As single-screw extruder and twin-screw extruder in the structure and working principle of the difference in the PVC profile production process control is also very different, in particular in:
1, temperature control
Single-screw extruder generally use the temperature gradually increased control method, the material in the feeding section should be in an unmelted solid state in order to facilitate the ability to achieve solid delivery, if the material premature melting will hold in the feed section of the screw synchronization with the screw Rotate to prevent the material moving forward, can not form a solid plug delivery capacity, the extruder squeeze out of material, a long time will result in the decomposition of PVC. From the feeding
Mouth to the nose of the temperature distribution shown:
Feed section
Melting section
Homogenization section
Head body
Die
140 ~ 150 ℃
160 ~ 170 ℃
170 to 180 ° C
180 ~ 185 ℃
180 ~ 185 ℃
Twin screw extruder and single screw extruder delivery mechanism of the material is different, it is the use of mandatory feeding side
law. As soon as the PVC material enters the extruder, it passes through the radial gap between the two screws and is strongly sheared, stirred and calendered, and quickly plasticized to vent into the exhaust section. If the PVC material is not well plasticized, not only to increase the load of screw extrusion, while entering the exhaust section, the powdery PVC material will be with the air together.