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.

组装精度分析是用于控制产品组装质量的基本技术之一。现有的组装精度分析方法集中于识别由零件的制造误差引起的组装偏差。他们不太重视组装过程中的影响因素，这些因素会显着影响分析结果的可靠性。另外，缺少零件模型的装配知识会导致装配仿真效率低下。为了解决这些问题，本文提出了一种基于通用零件数字孪生模型（PDTM）的装配精度分析方法。提出的PDTM集成了多源异构几何模型，并将装配信息从装配语义映射到几何元素，允许零件的自动装配定位并提高装配仿真的效率。除了制造误差外，还考虑了装配位置误差和配合表面变形，以量化对装配产品关键特性的影响。基于对接面的实际对接状态模拟，结合小位移转矩理论和蒙特卡洛方法，对实际装配中的装配定位不确定性进行了仿真。此外，可以将配合面变形叠加到装配间隙计算的结果中，从而提高了分析结果的可靠性。最后，