Chuanzhi Sun, Danyang Chen, Chengtian Li, Yongmeng Liu, Zewei Liu, Ming Hu and Jiubin Tan
This paper aims to provide a precision assembly method to improve the aircraft engine quality of initial unbalance with the purpose of founding the process for mass eccentricity…
Abstract
Purpose
This paper aims to provide a precision assembly method to improve the aircraft engine quality of initial unbalance with the purpose of founding the process for mass eccentricity propagation and demonstration of assembly process. The proposed method can be used for assembly guidance, tolerance allocation and so on, especially for the assembly with a large number of rotors and the assembly requirements of initial unbalance and coaxiality in high precision.
Design/methodology/approach
This paper proposes a constrained optimization-build method to minimize initial unbalance of aircraft engine assembly, which takes amount of unbalance and concentricity of each rotor into account. A constrained nonlinear programming model is extracted by choosing the initial unbalance as the objective function, and choosing the coaxiality and assembly orientations as the nonlinear constraints. The initial unbalance is reduced stage-by-stage by controlling the assembly angle of each rotor.
Findings
The validity and accuracy of the proposed method is verified by the multistage rotors assembly through experiments run with the measuring instruments. Compared with the direct-build method, the initial unbalance of final assembly using proposed method is reduced by 22.2% in four rotors assembly.
Originality/value
Different from the geometric eccentricity propagation control methods to reduce the initial unbalance indirectly, this paper establishes mass eccentric propagation model in multistage rotors assembly of aircraft engine for the first time. It provides a new idea to establish the relationship between the amount of unbalance of each rotor and the initial unbalance of multistage rotors.
Details
Keywords
Chuanzhi Sun, Yin Chu Wang, Qing Lu, Yongmeng Liu and Jiubin Tan
Aiming at the problem that the transmission mechanism of the assembly error of the multi-stage rotor with saddle surface type is not clear, the purpose of this paper is to propose…
Abstract
Purpose
Aiming at the problem that the transmission mechanism of the assembly error of the multi-stage rotor with saddle surface type is not clear, the purpose of this paper is to propose a deep belief network to realize the prediction of the coaxiality and perpendicularity of the multi-stage rotor.
Design/methodology/approach
First, the surface type of the aero-engine rotor is classified. The rotor surface profile sampling data is converted into image structure data, and a rotor surface type classifier based on convolutional neural network is established. Then, for the saddle surface rotor, a prediction model of coaxiality and perpendicularity based on deep belief network is established. To verify the effectiveness of the coaxiality and perpendicularity prediction method proposed in this paper, a multi-stage rotor coaxiality and perpendicularity assembly measurement experiment is carried out.
Findings
The results of this paper show that the accuracy rate of face type classification using convolutional neural network is 99%, which meets the requirements of subsequent assembly process. For the 80 sets of test samples, the average errors of the coaxiality and perpendicularity of the deep belief network prediction method are 0.1 and 1.6 µm, respectively.
Originality/value
Therefore, the method proposed in this paper can be used not only for rotor surface classification but also to guide the assembly of aero-engine multi-stage rotors.
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Keywords
Lei Wang, Chuanzhi Sun, Jiubin Tan, Bo Zhao and Gu Wan
This paper aims to provide an assembly method to improve cylindrical components assembly quality. The proposed method not only could be applied to tolerance allocation, but also…
Abstract
Purpose
This paper aims to provide an assembly method to improve cylindrical components assembly quality. The proposed method not only could be applied to tolerance allocation, but also could guide the assembly of cylindrical components.
Design/methodology/approach
The paper claims to provide a stack-build assembly method using a connective assembly model to take the location and orientation tolerances of a rotor stage into account. Through the separate analysis of the location and orientation tolerances propagation process in the assembly, the quality of the final assembly of the rotationally symmetric cylindrical components assembly could be improved by properly selecting component orientations to minimize the eccentric deviation in the assembly.
Findings
The effectiveness of the proposed stack-build assembly technique in improving the tolerance propagation in the assembly of cylindrical components was verified through experiments run with a measuring machine. A real aero-engine rotor was assembly using the proposed method; compared to the direct-build assembly technique, which had the component orientations without consideration, the stack-build assembly technique could be used to reduce the eccentric deviation in cylindrical components assembly by nearly 50 per cent.
Originality/value
Different with the old methods, the new method defined the tolerances in detail, such as perpendicularity and angle of the lowest point, and could guide the assembly by the features of surfaces on different components. Through measuring the special tolerances of surfaces on the components, the best assembly angle for each component could be obtained.
Details
Keywords
Qian Li, Wei Gao and Jiubin Tan
The purpose of this paper is to justify the algorithm optimization based on a consideration of its accuracy characteristics in a pure coning motion, which is widely used in…
Abstract
Purpose
The purpose of this paper is to justify the algorithm optimization based on a consideration of its accuracy characteristics in a pure coning motion, which is widely used in optimizing strapdown attitude algorithms to describe the special angular motion of a vehicle.
Design/methodology/approach
Two more general angular motions of a vehicle were given: generalized vibration describing periodical motions and benign dynamic describing aperiodical motions. The algorithm performances were evaluated in these two motions.
Findings
The theoretical analysis and numerical results show that errors of the algorithm optimized in pure coning motion are null or neglectable in these two motions, and performance of the optimized algorithm in a pure coning motion is superior to that of the non-optimized algorithm.
Originality/value
The value of the paper lies in that the authors justify the concept optimizing strapdown attitude algorithms in a pure coning motion.