| Assembly is an important link of aeroengine manufacturing process, the workload of which is more than half of the whole machine production, and how to control assembly precision is one of the key technologies of aeroengine manufacturing. The rotor of aeroengine is working in an environment of high temperature and high pressure. If the concentricity of rotor is not up to standard during assembly process, the rotor will be unbalanced. When engine is working, the imbalance may cause unnecessary vibration or friction between rotor and stator. This problem will reduce the propulsive efficiency or broken the engine. So the assembly precision of aeroengine rotor has a great influence on the whole engine performance.At present, engineers of our country only consider the effect of size tolerance on assembly accuracy in the stage of aeroengine rotor structure design. They assume the tolerances are all normal distribution, and calculate dimens ion chains by hand. The solving method is limited to worst case method and root sum square method. This design method is of low effic iency, and ignoring geometric tolerances and the fact that in practical manufacturing tolerances are non-normal distributions. It also leads to low qualified rate and repeatedly debugging in actual assembly process.The above questions that the assembly quality of aeroengine rotor is difficult to control at the design stage are solved through three aspects in this article. First of all, in the early stage of design, according to the fact that three-dimens ional entity model is not set up, we establish a 2-D rigid dimension chain model containing size tolerance and geometric tolerance. Then we study the assembly quality when tolerances are with different probability distributions and MATLAB is used to do the simulation. Secondly, in detail design stage, we use commercial tolerance analys is software Vis VSA to build a 3-D dimension chain model. Then we study the various factors influencing assembling deviation. At last, in the stage of optimization, in order to control the assembly quality of aeroengine rotor, we consider the actual manufacturing process, optimize the various influence factors, and summarizes a set of optimal design process.The main research work of this article is as follows:(1) The structure and assembly characteristics of aeroengine rotorThis part introduces the overall structure of aeroengine rotor, the structure characteristics of turbine rotor and compressor rotor, the assembly characteristics of rotor parts and the requirements of precision control. A CAD drawing of aeroengine is explained in detail about its transitive relation of dimension chain, tolerance annotation and measurement requirements. This drawing is the input of following research.(2) 2-D dimension chain modeling and analysis of aeroengine rotorIn this part, we establish a 2-D dimension chain model containing size tolerance and geometric tolerance about aeroengine rotor. Then we use Pearson distribution family to study the assembly quality when tolerances are with different probability distributions. The accuracy of the model was verified by Monte Carlo simulation.(3) 3-D dimension chain modeling and analysis of aeroengine rotorIn this part, we use commercial tolerance analysis software Vis VSA to build a 3-D dimension chain model. Through the calculation of assembly qualified rate and contribution rate, we study how assembly quality of aeroengine rotor is influenced by factors like s ize of tolerance, probability distribution of tolerance, assembly benchmark, measurement benchmark and assembly sequence.(4) Design optimization of aeroengine rotor for manufacturingIn this part, according to the results of the former research, we summarize a set of optimal design process for aeroengine rotor. Eight measurements of an engine are optimized using this process, which proves the effectiveness of the process. We also use genetic algorithm to optimize the installation angle of rotor parts. This method can effectively guide the actual assembly process. |
PDF Full Text Request