Single VS Twin Screw Precision Plastic Extruder

The main components of the twin-screw precision plastic extruder production line are similar to the single-screw precision extrusion production line. The differences between the two extruders are: There are two screws with the same structure in the barrel of the twin-screw plastic extruder machine; The feeding part of the barrel is a screw forcibly feeding into the barrel; the specifications and arrangement of the bearings for the two screws are more complicated. The main components of the twin-screw precision extruder are as follows:

1. Screw structure

1) The screw structure is divided into components according to the threaded part

Integral screw structure twin-screw extruder and combined screw structure twin-screw extruder, the integral screw is divided into the cylindrical screw and conical screw with gradually changing outer diameter according to whether the diameter of the threaded part is the same. It is divided into pitch gradually changing screw and thread wide changing screw.

2) According to whether the axis lines of the two screws are parallel or not, the twin screws are divided into two cylindrical screws with the same diameter, and the two screws are parallel to the forehead axis after assembly, and the diameter of the two screws gradually changes from large to small. The two conical screws with non-parallel screw axis after chemical and assembly.

2. Barrel structure

The barrel structure of the twin-screw extruder is the same as the barrel structure of the single-screw extruder. It is also divided into an integral barrel and a segmented combined barrel; in a twin-screw extruder, a counter-rotating twin-screw is engaged And conical twin-screw extruders generally use integral barrels; only a few large extruders use segmented combined barrels, the purpose is to facilitate machining and save some more expensive alloy steel; meshing co-rotating double Most screw extruders use segmented barrels. The segmented barrel is divided into several sections of equal length. Some barrels are provided with a feeding port, some barrels are provided with an exhaust port, and some barrels are provided with an additive port, and then the sections are connected with screws Into a twin-screw combined barrel.

3. Bearing arrangement for bearing axial force of twin-screw

4. Feeding device

The working characteristics of the twin-screw in the twin-screw extruder require that the feeding device adopts the metering feeding method to feed the barrel. The structure of the metering and feeding device is like an independent single-screw extruder. The screw that rotates the raw material is driven by a DC motor through a worm gearbox. The speed of the screw and the amount of material conveyed are determined by the working speed of the twin-screw and the barrel Temperature, mold forming pressure and the amount of material used to produce the product are determined. This feeding uses the screw thread, but single-head or double-head, generally single-head thread is used. If powdered materials are used for extrusion, in order to prevent the "bridging" phenomenon of the raw materials in the hopper, a spiral stirring device should be added to the hopper.