The Research Of Mechanical Property Of Contact System Of Rotary Kiln With Multi-supports And Parameters Optimization

Rotary kiln is the key equipment in many industrial departments, such as building materials industry, metallurgical industry, special waste treatment industry etc. One malfunction will bring interruption to the whole procedure, and make great loss, so safe and efficient running is the crux to improve benefit of the relevant enterprise. For building a whole design and adjustment theory system of rotary kiln, its mechanical mechanism, structure optimization and running condition adjustment are studied deeply.The formulae of dynamic repose angle is deduced, the mathematic model of convective heat transfer between bed and covered wall is set up, the formulae of radiant heat transfer among gas, bed and wall is obtained, the complex heat transfer model is established under the condition of multi-parameters and high coupling. A fourth-order Runge-Kutta method is employed for the solution of the complex model, as a result the axial temperature distribution of gas, bed, wall and shell are obtained.According to the deflection coordination condition of shell, the distribution rule of contact angle and the contact pressure between shell and tyre are obtained. The decomposing method of contact problems is put forward, and the large contact system of rotary kiln is decomposed into the contact system between shell and tyre, between tyre and roller, and between tyre and roller axle. By setting forth pseudo contact element, the contact system between roller and roller axle is solved with FEM method. The contact FEM model between tyre and roller under oblique pressure is studied. Adopting uniform design method and FEM method, the mechanical property formulae are fitted. By applying sub-structure technology, the multi-body contact model between shell and tyre is set up. Thus the following conclusions can be drawn out from these studies: the contact stress between roller and tyre is reduced gradually from contact center to contact boundary; the cross-section equivalent stress of tyre will alter 5 times per cycle, the periodic variational stress will lead to the fracture of tyre; the equivalent stress of support shell is far larger than that of middle shell, the strength of support shell is weaker than that of middle shell and the strength of middleshell is higher than needed.The general FEM solution of kiln support force under complex condition is studied. The formulae between kiln support force and axis deviation are obtained. Some conclusions can be drawn from the study: the axis deviation at the middle support has greater effect on the kiln support force than that at the boundary support; the kiln support force is effected deeper by its own support and the adjoining supports than other supports; middle deviation influence load distribution mostly. The vertical deviations influence load distribution on every support while horizontal deviation affect roller force.Combined fuzzy optimization with FEM, the optimization model of shell structure is set up. With the help of sub-problems approximate method, the results are achieved which show that the maximal equivalent stress, the maximal support force and the ellipticity of shell are reduced, so that the fatigue safety coefficient of shell is increased and the ability to resist abrupt load is strengthened by the structure optimization of shell.By applying nominal stress method and local stress-strain method, the fatigue damage models of support system are set up, the selective principle is the local plastic deformation. By minimizing the fatigue damage of tyre and of support system, the optimization model of support angle of tyre is built up. By solving the model, the conclusion can be drawn as follows: when the support angle of tyre is 30°, the tyre life is far less than that of the optimal support angle of tyre, and it is unsuitable to stipulate such support angle as 30° in traditional design.Based on the adjustment of the running condition of rotary kiln, taking the equilibrium of the roller force and the minimization of the relative axis deviation as the optimizing goal, considering the fuzzy factors of axis adjustment such as the single adjustment quantity of axis, absolute axis deviation, transmission system, the seal of the head and the end of rotary kiln, the tyre deformation and the contact stress between roller and tyre, the fuzzy optimization model of running condition adjustment of rotary kiln is set up. The fuzzy model is solved by applying maximum-minimum method, weighted average method, and fuzzy synthetic evaluation method It is showed that fuzzy optimization can distribute kiln load more evenly andmake axis deviation straighter under the condition of large axis deviation than common optimization and routine adjustment. It is ideal to improve the running condition of rotary kiln by employing fuzzy optimization.To sum up the theoretical harvest, the monitoring and optimizing system is developed which contains monitoring, analyzing, managing function. Applying the system, the past axis status can be consulted, the variational trend of axis can be forecasted, the roller force can be showed, and the adjustment parameters can be optimized. The system has friendly surface, stable function, high reliability and strong adaptability to bad environment with high temperature and much dust.