Research On The On-line Quality Control Mechanism Of Remanufacturing Assembly Process For Complex Mechanical Products Under Uncertainty

In the present world, the resource depletion and environmental disruption have seriously influenced the rapid development of manufacturing industry. Application and promotion of remanufacturing is one of the most optimal approaches to solve this problem, and has become an important technology for the realization of sustainable development and ecological civilization.However, there are two contradictions existing in remanufacturing engineering currently. For one thing, the remanufactured product is low-carbon and environmentally friendly, but the quality of remanufactured product could not meet the requirement of customers. For another, the market demand of remanufacturing market is huge, while the scale of remanufacturing industry is small. Therefore, the key factor for the scale development of remanufacturing industry is to guarantee the quality of remanufactured product not less than that of the original one. To ensure the reassembly quality and the performance of remanufactured product in uncertain reassembly environment, it is urgent to conduct on-line quality control during the large-scale reassembly process. And it has become one of the key matters to be resolved in prompting the core competitiveness of remanufacturing industry.Initially, this dissertation illustrates the current situation of remanufacturing industry at home and abroad, and elaborates the development situation of remanufacturing industry policy in our country. Meanwhile, it summarizes the current research status of reassembly quality, analyzes the overall characteristics of reassembly quality research, and also introduces research purpose, research significance, and general framework.Then, to improve the reassembly quality of complicated mechanical equipment in uncertain environment, this thesis explores the definition, measurement and optimization mechanism for reassembly uncertainty. It also studies the online quality control method for reassembly process. The main content of this part is as follows:(1) This dissertation analyzes the uncertainty of remanufacturing assembly. The relative uncertainty potential is established by making a comparison among ideal manufacturing and original manufacturing and remanufacturing. This dissertation analyzes the uncertainty of remanufacturing assembly. The relative uncertainty potential is established by a comparison among ideal manufacturing, original manufacturing and remanufacturing. It also quantitatively represents the reassembly uncertainty in introducing the concept of entropy into reassembly uncertainty measurement. Taking remanufactured engine cylinder block and head as the research object, the effectiveness and feasibility of the uncertainty measurement model is verified.(2) On analyzing the input vectors, state vectors and output vectors of each reassembly station, the state space model of reassembly station is constructed. The error transfer function of reassembly process is built and the decoupling control algorithm is established to reveal the engendering, transmission, fusion, and coupling mechanism of reassembly uncertainty. The error transfer function provides the theoretical basis for reassembly error compensation, precision adjustment and the on-line quality control.(3) This thesis establishes the uncertainty measurement model of remanufactured parts, and researches the dimension entropy coupling mechanism of parts’ generalized assembly. Taking complex mechanical product assembly as the research object, with consideration of the minimized cost and quality assurance for the product, the remanufacturing classification matching method oriented to uncertainty is put forward by the particle swarm intelligent algorithm. The application example verifies that the method can decrease the uncertainty of reassembly process, improve the reassembly quality and prompt the production efficiency effectively.(4) On the basis of the state space model for reassembly process, the reassembly quality transfer function is built, and the technological operation modified index of reassembly station is calculated. Then, the on-line quality control equation of reassembly process is given by classification theory. Moreover, this dissertation studies the on-line quality control method for the axial clearance and gyroscopic moment of remanufacturing crankshaft. These two examples indicate that the on-line quality control method can promote the assembly precision of remanufactured crankshaft effectively, while the attribute bound of remanufactured parts is expanding.Finally, the reassembly quality control platform is designed and developed to apply the on-line quality control method to actual reassembly process. This platform can realize the definition, measurement and optimization of the reassembly uncertainty, and provide technical support t for reassembly on-line quality control.