Mission Reliability Modeling Method of Assembly Process Considering Workpiece Quality Deviation

In recent years, assembly system has been developing towards multi-state, complexity, large-scale and intelligent trend, and complex assembly tasks and assembly processes as well as dynamic and changeable assembly environment have reduced the mission reliability of assembly system, resulting in low quality and low reliability of assembly products. In addition, with the large-scale and complex structure of assembly product and the deterioration trend of service environment is becoming more and more obvious, people have higher and higher requirements for its reliability and quality. Therefore, this paper proposes a mission reliability modeling method of assembly process considering workpiece quality deviation. Firstly, the connotation of assembly process mission reliability is proposed on the basis of clarifying assembly system components and operation principle. Secondly, from the perspective of system theory, the conceptual model of PQR chain, which is embodied as the chain conceptual model of assembly machine performance state (P), assembly process quality (Q) and product reliability (R), is innovatively proposed to analyze the relationship among assembly machine performance state, assembly process quality and assembly product reliability. Thirdly, the assembly process operation quality data is highly integrated and applied to the PQR chain, and the assembly process mission reliability model considering the workpiece quality deviation is established. Finally, the feasibility of the proposed method is verified by a double nozzle flapper valve assembling example.