Research On Process Optimization Of Aeroengine Rotor Assembly

Assembly is the final stage and the core of aeroengine manufacturing.The service performance of the engine is affected directly by Assembly quality.High-pressure compressor is the main power component of aero-engine.It is often in the state of rapid rotation,high temperature and high pressure at work.Once the assembly precision is disqualification,there will be vibration or friction between rotors during operation,affecting the reliability and stability of the engine.The structure of rotor is precise and the assembly process is complex.According to the project requirements,this paper mainly considers two steps: installation phase adjustment and connection bolt tightening process.Concentricity is one of the important indices for evaluation of multi-stage rotor assembly accuracy.The concentricity calculation model after rotor assembly is created based on the measured pulse data.Taking the results of prediction as the objective function and the installation phase as control variables,multi-stage rotor assembly precision optimization equation is derived and the equation is solved by the improved genetic algorithm.When all levels of the rotor assembly phase is used in assembly,the fitting precision of the rotor is improved.The bolt tightening process is improved from single bolt and bolt group tightening.The influence of tightening sequence,times and steps is analyzed by finite element method and the principle of tightening process design of bolt group is obtained through experimental verification.The main research contents of this paper are as follows:The research on the determination of the rotor assembly phase of assembly step 1 was carried out.Firstly,the concentricity is used as the evaluation quantity to analyze the acquisition method of rotor assembly error under a certain phase.This paper proposes a calculation method of rotor assembly deviation under specific phase based on micro-morphology data.According to the special joint structure of the rotor,the eccentricity and deflection are calculated in axial and radial directions respectively and the assembly connection model based on coordinate transformation is established in the stacking process.The deviations of the rotors at all levels are transferred and accumulated in the corresponding coordinate system and finally,the concentricity of the composite parts of the rotor is extracted.Experiments show that the prediction based on runout data is more accurate than other methods.Then considering assembly phase optimization for multi-stage rotors,an assembly precision prediction model is introduced and a phase optimization equation for rotor concentricity is established with the characteristics of rotor structure constraints.Based on the form of the problem and the optimization equation,the operator and parameters of the genetic algorithm are adjusted.Finally,the Accuracy and efficiency of algorithm is analyzed.By analyzing the optimization results of the genetic algorithm,it can be found that when the rotor concentricity is used as the optimization target,the concentricity deviation of the intermediate rotor is larger than standard.It means the multi-stage rotor’s coaxiality error is overlarge.In this chapter,a multistage rotor assembly phase optimization method for rotor coaxiality is studied.Coaxiality constraints are added into the assembly phase optimization equation and a hierarchical/adaptive dynamic penalty function is designed as a penalty function term in the genetic algorithm to make the algorithm suitable for solving the coaxiality optimization problem.Finally,the optimization results are verified.After the installation phase is determined,considering the tightening process in the rotor connection.When the aeronautical rotor bolt group is tightened,it is important to study the final pre-tightening force with lower dispersibility by improving the tightening process.Firstly,the tightening process of single bolt is analyzed,including determining the calculation method of target pre-tightening force and comparing the differences of torque method and torque/angle method.In addition,based on the finite element model of bolt group,the elastic interaction during tightening is simulated and the influence of tightening sequence/times/steps on the final pre-tightening force of bolt group is obtained.Finally,the simulation analysis and test results are compared to analyze the actual influence of the above factors on the final pre-tightening force dispersion and summarize the rules when design the multi-bolt tightening process.