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Single screw extruder As the screw and machine design is simple, easy to manufacture, low prices, so in the plastic processing industry has been widely used. But with the development of the plastics industry, in the processing of new materials and their blends, and rigid PVC powder, single screw extruder showed a lot of limitations, mainly in the following areas:

① because the single screw extruder is mainly dependent on the role of friction, so the feeding performance is limited, powder, fiberglass, inorganic fillers more difficult to join;

② because the single screw exhaust extruder material in the exhaust area of the surface update effect is small, so the exhaust effect is poor;

③ Part of the mechanical single screw extruder is not suitable for certain processes, such as polymer coloring; because these processes require the material in the barrel of the residence time is short, but also fixed. The residence time of the material in the single screw extruder is generally longer, and the residence time of the material is not equal. Another example is the mixing of thermosetting powder, the temperature, pressure and other conditions are very strict, single screw extruder can not meet the requirements.

In order to solve the above problems, a twin screw extruder was developed. Twin screw extruder has the following characteristics:

① easy to charge: twin-screw extruder by the principle of positive displacement of the material, there will be no pressure back. In the single-screw extruder is difficult to join, there are very high or very low viscosity, and with a wide range of metal surface friction coefficient of materials, such as ribbon, paste, powder, glass, etc. can be added ; Glass fiber can also be added in different parts. Twin screw extruder is particularly suitable for processing PVC powder, powder can be directly extruded PVC pipe, profiles.

② material in the twin-screw extruder to stay short time: suitable for those who stay too long will cure or cohesion of the material coloring and mixing, such as thermosetting powder coating material extrusion.

③ excellent exhaust: due to the twin screw extruder meshing part of the effective mixing, exhaust part of the self-cleaning function makes the material in the exhaust section can get a complete surface update.

④ excellent mixing and plasticizing effect: As the two screw meshing, the material in the extrusion process than the single screw extruder more complex movement, subject to vertical and horizontal two-way shear mixing.

⑤ lower than the power consumption: the twin screw extruder screw diameter is relatively short, the material energy from the external heat input; and single screw extruder screw diameter to diameter ratio of 20 to 30%, and The head and manifold screens increase resistance, so the same yield of twin screw extruders is 50% lower than the energy consumption of single screw extruders. Zhangjiagang City Huade Machinery

⑥ twin-screw extruder volumetric efficiency is very high: the screw characteristic line is hard, the flow rate of the mold pressure changes are not sensitive to the extrusion of large cross-section of the product is more effective, especially when the extrusion is difficult to process the material. The flow rate of the single screw extruder is relatively sensitive to the change in the die pressure.