The twin-screw extruder is divided into an engaging type and a non-engaging type according to the relative positions of the two screws. The mesh type is divided into a partial mesh type and a full mesh type according to the degree of meshing. The twin-screw extruder is divided into two types: the same direction rotating screw and the reverse rotating screw according to the screw rotating direction.
Below, Xiaobian will give you a brief introduction about the technical problems of twin-screw extruders.
1. Increase the screw speed, which is conducive to bubble formation, growth and rupture, which is beneficial to reduce the filling length of the material in the screw groove, enhance the renewal effect of the material mass transfer surface, and improve the devolatilization efficiency; however, the excessively high speed makes the material The residence time in the devolatilization section is drastically reduced, and the devolatilization efficiency is rather decreased.
2. The main screw speed, feed amount and barrel set temperature are the main influencing factors of the devolatilization process in the twin-screw extruder. These factors can affect the material temperature, the groove fullness, the residence time and the effective full length, thus affecting the devolatilization in many ways. For a specific process, there is an optimum working point, and in the case of stable operation, the highest devolatilization efficiency can be obtained.
3, appropriate reduction of feed can reduce the filling rate of the exhaust section, so that the devolatilization efficiency is improved; but too low feed volume not only reduces the amount of extrusion and fluctuations, but also because the filling rate is too low, not enough to form a melting The pool reduces the efficiency of foaming and devolatilization, so the amount of feed must be moderate.
4. Increasing the residence time of the material in the devolatilization section and increasing the length of the devolatilization section can improve the devolatilization efficiency. For this reason, it is considered to increase the length of the exhaust section and adopt multi-stage exhaust in the screw structure design.
Post time: May-16-2019