An assembly precision analysis method based on a general part digital twin model

Assembly precision analysis is one of the fundamental technologies used for controlling the assembly quality of products. Existing assembly precision analysis methods focus on identifying the assembly deviation caused by manufacturing errors of parts. They place less emphasis on the influencing factors in the assembly process, which significantly affect the reliability of the analytical results. Additionally, the lack of assembly knowledge for part models leads to a low efficiency of the assembly simulation. To address these problems, this paper presents an assembly precision analysis method based on a general part digital twin model (PDTM). The proposed PDTM integrates multi-source heterogeneous geometric models and maps assembly information from assembly semantics to geometry elements, allowing automatic assembly positioning of parts and improving the efficiency of assembly simulation. In addition to the manufacturing errors, the assembly-positioning error and mating-surface deformation are considered to quantify the impact on the key characteristics of the assembled product. Based on the real mating status simulation for the mating surfaces, the uncertainty of assembly positioning in an actual assembly is simulated by combining the small displacement torsor (SDT) theory and the Monte Carlo method. Furthermore, the mating-surface deformation can be superposed to the result of the assembly-gap calculation, improving the reliability of the analytical results. Finally, a prototype system and a case study involving a load-sensitive multi-way valve assembly process are introduced to demonstrate the applicability of the proposed method.