Some Functions Of The Three-screw Granulator
The three-screw granulator is determined by its structural principle. After the material is fed into the machine, it has been plasticized in the 6D length due to strong shearing, and then banburying is mainly carried out in the central area formed by the three screws. Taking a 3-Φ60 machine as an example, when the length-diameter ratio is 32 and the screw speed is 500 rpm, the number of times the material is repeatedly and strongly kneaded in the central area is (32-6)×500×3=39000 times/min . Just imagine what kind of material can not be fully plasticized and evenly dispersed?
The three-screw granulator has a wide range of residence time, which is more conducive to the processing technology with short residence time and long residence time. The process of reducing the molecular weight of cross-linked polyethylene requires that the long carbon chain of cross-linked polyethylene be degraded as completely as possible into small molecular substances with narrow molecular weight distribution. As long as the aspect ratio is about 36:1, the straight three-screw can achieve better plasticizing and mixing effect. The powerful shearing function and excellent self-cleaning performance of the three-screw make the material exchange and flow repeatedly between the screws. Due to the excessively fast rotating speed of the main engine, the residence time in the barrel is short, and the plasticization is not completely uniform, and the residence time is relatively prolonged. In order to ensure the reduction degree of the cross-linked polyethylene molecular chain, the three-screw control of the reaction temperature and screw speed is more accurate than that of the twin-screw, which is very beneficial to extrusion.
In the polyethylene graft reaction extrusion process, the material is required to stay in the barrel for as long as possible, and the amount of the initiator is limited, which requires the dispersion of the initiator in the system to be uniform, so that the grafted product can be dispersed in the initiator. Grafting to the resin as uniformly and completely as possible under the action of The advantage of twin screw is obvious, it is often formed by its high speed and high shear. When preparing engineering plastics such as pet and PBT, and alloy materials such as PC/PBT, a straight three-screw with a small aspect ratio is used to make the residence time of the material as short as possible to avoid thermal decomposition of the ester bond, and the shearing is uniform and effective. Excellent plasticizing effect can also be achieved. The advantages of triangular three-screw in this respect are more prominent, requiring smaller aspect ratio and better shear dispersion effect. The three-screw granulator has low energy consumption. With the increase of screw speed, the output of the three-screw granulator is larger than that of the twin-screw, and the positive displacement conveying capacity is strong. Its aspect ratio is short, and the screw length is only half of the conventional twin-screw, which greatly reduces the energy consumption. It increases the free flow space of the material in the barrel, which is beneficial to reduce the screw torque, thereby reducing the energy consumption. It occupies less space than the general twin-screw machine, and consumes much less energy such as water and electricity.
For more inquiries, please pay attention to Nanjing Kelongweier Chemical Machinery Co., Ltd.!