Parallel and conical twin screw plastic extruder

Update:26-01-2019
Summary:

Parallel twin-screw extruders are limited by the small […]

Parallel twin-screw extruders are limited by the small center-to-center distance of the two screws. In the transmission gearbox, the space for the radial and thrust bearings supporting the two output shafts and the associated transmission gears is limited, although the designer has exhausted Brain juice, but it can not solve the bearing capacity of the bearing, the modulus of the gear, the small diameter, and the small diameter of the tail of the two screws, resulting in poor torque resistance. The output torque is small and the load resistance is poor, which is the most significant defect of the parallel twin-screw extruder. However, the plasticity of aspect ratio is the advantage of parallel twin screw. It can increase and decrease the aspect ratio to meet the requirements of plastic processing technology according to the difference of molding conditions, and can expand the application range of parallel twin screw, but this cone Twin screw extruders are difficult to achieve.

The conical twin-screw extruder has two conical screws arranged horizontally, and the two axes are inserted into the barrel at an angle. The center distance of the two axes gradually increases from the small end to the big end, so that the two output shafts of the transmission gear box have With a large center distance, the gears and gear shafts in these transmission systems and the radial and thrust bearings supporting these gear shafts have a large installation space, which can accommodate larger radial bearings and thrust bearings, each The drive shaft has a shaft diameter sufficient to meet the transmission torque, so the large working torque and large load capacity are a major feature of the conical twin-screw extruder. This parallel twin-screw extruder is unmatched. When the twin-screw extruder's anti-backing twin-screw extruder is working, the melt will generate a very large pressure (head pressure) at the head of the screw. The pressure is usually around 14MPA, sometimes even as high as 30MPA or more. The pressure creates a strong axial thrust on the screw, and the thrust is the function of the thrust bearing.