Study On Parameters Optimization Of Intelligent-Efficient And High Quality Concrete Mixer

As the basic building material, the concrete is used widely in industry, agriculture, transportation, defense, water conservancy, municipal and civil application etc, and is playing an important role in the national economy. Concrete mixing is the key process in the production process, related to the quality and efficiency of the concrete production directly. Twin-shaft mixer is the mixer of the mainstream models. It has the advantages of small size, large capacity, reasonable structure, wide application range, better mixing quality, higher efficiency and so on. As the complexity of the mixing process, the parameters design of the mixing device has been studied by experimental results and working experience as a design basis at home and abroad. So it leads to long design period and slow technological innovation because of the lack of the theoretical support. Through the theoretical analysis of the main parameters of mixer, combined with the simulation of fluid simulation software and the results of existing experiments, the parameter optimization of twin-shaft is studied in this paper and provides theoretical basis and technical support for the same model engine.This paper first analyzed the motion state of materials in the process of mixing and the target relation expression of the parameter optimization was obtained. The criterion of a mixer mixing performance was introduced: to judge by the quality of concrete mixtures.Secondly, the theoretical analysis and software simulation of the main parameters were carried out separately, mainly including: rotation speed, the setting angle of mixing blades, the number of mixing arms, mixer's length-width ratio and mixing arms arrangement.This paper put forward the rational rotation speed determination should be studied by stages on the materials on the vane. Base on the force equilibrium analysis of the materials on the vane in falling state, this paper came to the conclusion that the range of the rational rotation speed of known machine type should be less than 1.53m/s, could reach 1.72m/s in the limiting case; While the materials in the state of squeeze, by using momentum equation of hydrodynamics, the minimum rotation speed corresponding to different coarse aggregate size was obtained. Integrating the results above, the paper draw a conclusion that the range of the rational rotation speed of this machine type was between 0.9063m/s and 1.72m/s.Through the kinematics analysis of the materials on the vane, combined with related knowledge of engineering fluid mechanics, the speed expressions in the axial and radial direction were obtained; Analysis on the movement characteristics of the materials which acquired better stirring effect, the projection region of rational material trajectory was obtained. According to the different mixer's length-width ratio, this paper came to the conclusion that the range of the setting angle of mixing blades were as follows: the range of the setting angle of width-short mixing blades was between 29.142°～32.865°; the range of setting angle of narrow-length mixing blades was about 42.168°. Then making the kinematics analysis of the materials on a single vane, the correctness of theoretical analysis on the setting angle of mixing blades was further verified according to the data calculated by substitution of different number of mixing arms.When to determine the number of the mixing arms, through the kinematics analysis of the materials on the vane, combined with related knowledge of engineering fluid mechanics, the speed expressions in the axial and radial direction were obtained; Analysis on the rotation angle of the single mixing axis which impels the movement of materials one axial length of the trough, according to the different mixer's length-width ratio and the range requirements of the rotation angle, the number of the mixing arms corresponding to different phase angle were obtained; Right to consider the different arrangement form of the twin-shaft mixing arms, the reasonable results came out on the basis of the arrangement principle of the mixing arms and blades eventually.As the goal of saving manufacturing materials, this paper came to the conclution that the mixer's length-width ratio was about 0.7. The range of the reasonable mixer's length-width ratio should be between 0.7 and 1.3 combined with the results of experiments. Through the analysis of the material flow and the mixing arms arrangement, this paper draw a conclusion that the mixing arms surrounding, zheng-zheng and cross arrangement were more reasonable. Finally, integrated the range of the parameters analyzed, the best parameter combination was obtained in theory.This study is not only a further discussion upon the parameters design of the mixing device, but also a further design innovation. And it provides an important reference for the design and the value of related parameters of the same model engine for the future.