Development Of The Mixing Equipment With Differential Intermeshing Rotors

Differential intermeshing mixer was developed to study the homogenizing effect and the mastication effect. Based on the characteristics of twin-rotor engagement, the unified profile equations were established by relative motion law, and a variety of differential elements were designed. Finite element method was used to analyzed the characteristics of the flow field and mixing effects. The bench of the mixer was built to study the mixing effects. The work and conclusions of this test were as follows:1. The constitutive equation parameters of high-density polyethylene were tested by the rheometer. Numerical method was used to analyze the shear rate and the pressure of the entire flow field and critical monitoring points. As a result, the optimum clearance between the rotor and the feed chamber was 0.3 mm. By means of mixing index and separation scales, mixing effectiveness of 1D cross-section of the intermeshing counter-rotor was compared. The speed ratios were 2:1,4:1 and 5:2. The mixing effectiveness of the rotors whose speed was 2:1 was better. The residence time, the maximum value of mixing index, shear rate and shear stress were used to compare the mixing effectiveness of the co-rotor(-3:1) and counter-rotor(3:1). The conclusions were as follows:The distribution ability of the differential counter-screw was better than co-rotating differential screw, but the dispersion ability was poorer; the distribution effectiveness and the tensile properties of the co-rotating differential kneading block were better, but the shearing effect was poorer than the counter kneading block. In addition, differential screw was simulated. The flow rate was linearly related to the speed, and a low speed leaded to a superior distribution efects.2. The bench of the differential twin-rotor extruder was built. The spiral rotor(4:1) was designed, and the drive motor and the inverter were selected. Also, the gear box and the cylindrical die were designed. Under different speeds and materials systems, the production and the outlet pressure were linely related to the speed. Minimum residence time of the material was short at high speeds by using tracer particle method, which was unfavorable for distributive mixing. High fluctuations of the outlet pressure caused by material viscosity leaded to the instability of the production. The bench of the differential disk-rotor mixer was built, and the rotors whose speed ratios were 3:2 and 5:2 was designed. Also,the adjustable gearbox and the material cavity were designed. The torque curves of the material were given at different rotor speeds. Under a high speed, peaks of the feeding and the plastics appeared earlier, and the corresponding torque values were grearer. According to the comparative analysis of the torque equilibrium value, and the maximum torque at differenti times, it was concluded that the mixing effects of 3:2 rotors was better. Mixing process of the materials were analyzed according to the appearance of the samples collected at different times. Polarizing microscope was used to view the mixing effects of the samples.3. Non-equal differential rotor mixer, star differential rotor mixer, and the ring differential rotor mixer were designed, and the design scheme of the transmission device was put forward. Research on cross-sectional mixing behavior of differential rotors (-3:1 and 3:1) was analyzed by numerical methods, the results showed that:Regardless of the configurations of the rotors, distribution effects of the co-rotor were better than the counter-rotor. For ring differential rotor mixer, the relationship between the differential ratios of the rotors and the number of polygon edges were received through the establishment of the regular polygon model to achieve the right peripheral engagement.