Twin-screw extruder - main parameters
Screw diameter. The screw diameter refers to the outer diameter of the screw in millimeters. For variable diameter (or tapered) screws, it is a variable value and should indicate which end diameter it is. Twin-screw extruders are generally organized into series by diameter. Most of the meshing counter-rotating parallel twin screws produced at home and abroad are in diameter, and the most commonly used ones are ~. The screw diameters of meshing counter-rotating parallel twin-screw extruders and meshing co-rotating twin-screw extruders are mainly determined based on the extrusion volume and the cross-sectional size requirements of the products used for production. The larger the screw diameter, the larger the extrusion capacity of the machine.
The center distance of the screw. The center distance of the screw refers to the distance between the center lines of the two screws. It is an important parameter. When designing a twin-screw extruder, from formulating the overall plan to specific structural design, it determines the following relationships and determines the relevant design parameters.
①The size of the output shaft of the transmission system (connected to the screw) and related gears determines the effective torque of the screw.
②The size of the outer diameter of the thrust bearing determines the maximum design pressure of the machine head.
③The outer diameter and root diameter of the screw determine the degree of meshing of the two screws, the depth of the screw groove and the maximum theoretical delivery capacity of the twin-screw extruder.
Screw length-to-diameter ratio. The aspect ratio of the screw refers to the ratio between the effective length and the outer diameter of the screw, which reflects the specifications and performance of the twin-screw extruder. Different types of twin-screw extruders have different length-to-diameter ratio ranges. For integral twin-screws, the length-to-diameter ratio is a fixed value, generally: for combined twin-screws, the length-to-diameter ratio is variable, and some can reach.
The steering of the screw. The screws of twin-screw extruders can rotate in two ways: co-rotating and counter-rotating. From the perspective of development trends, co-rotating twin-screw extruders are mostly used for mixing, while counter-rotating twin-screw extruders are mostly used for extruding products.
Driving power. Driving power refers to the motor power that drives the screw.
The torque that the screw bears. Twin-screw extruders are subject to larger torque loads. In order to characterize its load-bearing capacity and protect the safe operation of the extruder, the maximum torque that the screw can withstand and must not be exceeded during operation is generally listed in its specifications. The unit is generally represented by .
The bearing capacity of thrust bearings. The thrust bearing is an important component in the twin-screw extruder. The load-bearing capacity of the thrust bearing is generally given in the product specifications.
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