目的 为提高M型预制袋包装机袋口折合机构轨迹输出点的运动精度，对袋口折合机构进行运动精度可靠性优化。方法 在运动学分析的基础上，用环路增量法建立考虑杆长误差时袋口折合机构的位置误差模型，接着对轨迹输出点进行可靠性分析及蒙特卡洛法验证，通过灵敏度分析确定关键误差影响因素，最后进行运动精度可靠性优化。结果 建立的可靠性模型可以有效地反映杆长误差对机构运动精度的影响，x分量轨迹的可靠度由82.5%提高至92.91%，y分量轨迹可靠度由65.34%提高至89%。结论 经过可靠性优化能够使袋口折合机构运动精度满足设计要求。

The work aims to improve the kinematic accuracy of the trajectory output point of the M-shaped prefabricated bag opening folding mechanism, and optimize the kinematic accuracy reliability of the opening folding mechanism. Based on kinematic analysis, a position error model of the opening folding mechanism considering rod length errors was established according to the loop increment method. Then, reliability analysis and Monte Carlo verification were performed on the trajectory output points, and key error influencing factors were determined through sensitivity analysis. Finally, reliability optimization of motion accuracy was performed. The results showed that the reliability model established could effectively reflect the impact of rod length errors on the kinematic accuracy of the mechanism. The reliability of the x-component trajectory was increased from 82.5% to 92.91%, and the reliability of the y-component trajectory was increased from 65.34% to 89%. In summary, the reliability optimization can make the movement accuracy of the opening folding mechanism meet the design requirements.