Numerical Calculation And Strutral Optimization Of Spiral Groove Seal On The End Face Of Mixer Rotor

With the application of automation and intelligence in the production of internal mixers,the quality rubber compounds are becoming more stringent.The shaft seal of rotor is an important part of the mixer,the quality of the sealing device not only affects the composition of the rubber compound,but also affects the working environment and production efficiency.How to improve the sealing ability of the rotor becomes one of the main research contents of the mixer design,and achieving zero leakage of raw materials is the goal that manufacturers are constantly pursuing.The spiral grooves that are inversely conveying of the rubber compound are machined on the end of the rotor,preventing the leakage of the rubber compound from the root source and achieving the sealing of the rotor.The sealing structure retains the original sealing device and forms a double seal,therefore,it has broad application prospects.The main research contents of this article is as follows:1.Through consulting numerous relevant document,the existing internal mixer rotor shaft seals and existing problems were summarized.The mechanical effect of the spiral seal and the upstream pumping mechanism of the spiral groove seal at low viscosity were analyzed.The conveying mechanism of spiral groove of rotor for high viscosity fluid was proposed.A formula for the balance between pumping and leakage was established,and the influence of different factors on the sealing pressure were analyzed,which provided a theoretical basis for the spiral groove sealing of the rotor.2.A three-dimensional model of the spiral groove was established by Solidworks.The distribution of flow field(velocity,pressure,velocity vector)affected by spiral groove,differential pressure and comprehensive action was calculated by POLYFLOW.And effect of speed on sealing pressure was calculated.3.Taguchi method was used to optimize the structural parameters of the spiral groove.25 sets of schemes were designed by using orthogonal simulation tables to simulate the sealing pressure of different parameter combinations.Through the analysis of variance,the optimal parameter combination is obtained: Groove width was 13 mm,groove depth was 1.75 mm,helix angle was 25°,number of grooves were 12,groove bottom radius was 44 mm.The contribution rate of each parameter was calculated,the degree of influence of factors from large to small was Groove depth,helix angle,number of grooves,groove width,groove bottom radius.4.The effect of periodically changing end seal gap on sealing pressure was studied,the causes of the periodic axial agitation of the rotor were analyzed.the axial force and turbulence of the rotor were calculated.Considering the influence of thermal effect on rotor length,the thermal elongation of the rotor is calculated.Combining turbulence and thermal elongation,the range of periodic variations in the seal gap was determined.At last,the sealing pressure at different gaps was calculated.