Design And Analysis Of Impeller Blade

Along with the industrial development in our country, shot blasting equipments have been widely applied to the surface cleaning of forging, casting, pieces that have been welded and piecese that have been heat treated; to the surface preparation of rolled steel and section steel; to the surface intensifying of pieces like springs and gears wich support high stress. Besides, shot blasting equipments can also been applied to the surface treatment of vehicles, boats and areoplane. After development of one hundred year, the technics and equipments of shot blasting have been mature so that shot blasting not only is used in heavy industry, but also be used in the construction of roads. The quality and service life of the shot blasting directly depend on impeller blade. Rapidly rotating blades have the function of accelerating the pills and making the pills acquire some absolute velocity that be needed by the treated surface. So the blades had to be repeated impacted and wore by pills until they cease to be effect. According imperfect statastics, every year lost material only because of blades'attrition wear count for more than ten million in our country. That increasing service life of the impeller blades and reducing the lost material is the linchpin of costing down and enhancing the availability factor of throwing machine. That is the reason that the research institutes and experts who are dominal this area constantly study and explor how to increase the service life of impeller blades. They studied about how the blades cease to be effective, what material is better for the blades, what structure is better for the blades'carrying capacity and so on. But this paper is about to design the shape and structure of blades and to analysize the blades by method of finite element analysis and in the end to ameliorate the design of blades. The following paragraphs are about main content of this paper.Firstly, set the kinematic differential equation of pills according to a series analysis such as the pills'moving process on the blades and what and how force, velocity and acceleration is applying on the pills during this process. Via working out the differential equation we can know the pills'absolute velocity at the time it is thrown out of the blades and the pills'forces applied by the blades when the pills move on them. Thus the relation of the velocity and the parameters of blades and the relation of the foces and the parameters of blades are determined.Secondly, the inside and outside diameters of different structure blades can be worked out if the velocity that the treated surface needs and the rotate speed restricted by the bearing which drive the impeller rotate are given. In this way, the elementary design of different blades is completed. And then the loads apllied on the blades can be affirmed by analysizing how the forces applied on the blades. The constraints apllied on the blades can be affirmed by the way blades fixed on the impeller. In the end the simplified models of different blades are building in CATIA and the .CATPart files will be set.Thirdly, after transferring the .CATPart files into the ANSYS program, analysis of the blades in ANSYS can be done. Before analysis, it is necessary to pre-process the transferred models. This pre-processing includes building reasonable coordinate system for the models and choosing befitting element to mesh and defining material properties for the models and applying correct boundary condition on the models. Correct pre-processing key to working out more exact result of finite element analysis. Here the elements of SOLID45 and SURF154 are choosen to mesh the models after comparing the analysis results of different ways to mesh. And nodal loads are choosen after comparing nodal loads with element loads. It is very difficult to apply loads on the nodals of the modal because the loads, pressure force and fictional force, are different in value and direction at different nodal of the work surface. The loads which like this are nonlineal loads can not be applied by GUI of ANSYS. So apllying loads and constraints need to creat respective macros with ANSYS Parametric Design Language. Not only creating macros deal with the diffcult of applying nonlinear boundary condition. But also it makes features of the model parameters so that one macro can apply boundary condition on different size of blades.Finally, after analyse the results of finite element anlysis of different blades, drawing the conclusions is listed following:Firstly, pressure loads applied by pills and inertial force because of rotation are the major factors which affected the stress distribution on the blades. After modal analysis and dynamic force analysis of blades, the results of static are enough because the first ten rank frequencies of the dynamic force are far fewer than the natural frequency of the blades.Secondly, the major part of the blade is in the low stress condition. But stress concentration will happen around the point which exist constraints saltation. The blades are broken just because it is affected by this repeated stress. So in terms of stress analysis and other literatures blades have two types of failure, one is wearing and the other is fatigue. Just because this two types of failure all come from stress concentration, reducing the degree of stress concentration can increase the blades'service life.Thirdly, the theory checking the blades intension is choosen via stress analysis and failure analysis. The first intension theory is used to check because the material of the blades is fragile material. The forth intension theory is used to check because the blades'failure come from local plastic deformation.Finaly, via studying how the parameters affect stress distribution, such as the length of the blades'constraints, the thickness of the blades, the curvature of the curve blades, the structure of the blades, the ways of ameliorate the blades'design are put forward. Above is the content of this paper. But the analysis of the blades is just elementary. This paper isn't involved in the anlysis of fatigue and wearing. So the service life of the blades can not be confirmed.