| Because of the complexity of blade surface features,the special material properties and the poor conditions where it works,the blades are limited to many restrictions when machined.Besides,it also brings some unique and high demands for its machine process technique.With the rapid development of numerical control technology,the manufacturing quality has also became better and better.And the machine method has gradually shifted from the previous profiling machien to the CNC machining due to the development of the numerical technology.The NC technology contains the already mature three-axis CNC and the popular five-axis machining which has been getting many scholars' and large business' s attention because of its high machining precision,high processing efficiency and good quality.But there are also some shortages for five-axis machining,such as expensive production costs and so on.Some manufacturers still use the previous outdated technology because of lacking of money.This raises a number of technical requirements to the three-axis machining blade process and the work of this paper is carried out on the basis of this requirements.(1)A clamp scheme of blade is proposed based on the anaylsis of the blade structure and a analysis of the machining method is also carried out.After the theoretical analysis,an inclined milling method is put forward.After the comparision of the commonly used vertical milling and inclined milling methods and the setting of the tool path which is set by the function of the MasterCam that can plan tool path automatically,an experiment is carried out under the same cutting parameters to analysis the features of each method.Then an instantaneous milling force model that can match this condition was built combined with the previous theory of other scholars in such inclined condition.Besides,the forces that participate in the milling and their effects to the quality of the blades are also analyzed.(2)The reasons that lead to to errors are also elaboraterd one by one,and appropriate and corresponding measurements were proposed in order to decrease even eliminate the effects.Except for those,the contact process of the milling tool and the blade was also analyzed along with the full calculation theoretically of error that caused by the tool deformation and its inaccurate position.Meanwhile the bend and torsional deformation of blade and the biggest deflection and rotation when it bears the milling force are calculated according to the knowledge of Mechanics of Material.In order to reduce error which bring by blade deformation and the milling tool deformation,the error control and compensation measurement were proposed inspired by the thinking of increasing the feed can reduce the deformation.(3)Finally the finite element model of milling machining of blade is established and simulated.The deformation of vertical milling and helical milling machining of blade can be analyzed by the finite element simulation,and then the deformation data are output to analyze and summarize the deformation law.Besides the experiment in the second part is also used to verify the correctness of the finite element analysis.Entering the error compensation technique after all the analysises are completed when the other experment is carried out under the same parameters as the first experiment to verify the validity of the technique.In addition,after inputing the error compensation technique,the finite element simulations of turbine blade under different direction of the cutter and different parameters are also carried out to analyze the effects of cut direction and parameters on deformation of blade,and choose the best cut direction and machining parameters for processing. |
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