基于装配载荷自适应的飞机大型整体结构件柔性精准定位策略研究

There is manufacturing variance between different aeronautical Large-size monolithic components, and over-constraints and forced locating often occur during the process of locating, so the locating process control is difficult, the locating result is difficult to reproduce, the locating quality is instability and so on. The concept of assembling load adaptive-based flexible precise locating, that is the digitized measured values of the locating quality are analyzed, calculated to obtain the adaptive readjustment plan of the assembling load for improving Location accuracy and lowering assembly stress, is proposed. The inspection requirements of the locating quality is analyzed, and the evaluation standard is quantized, the digitized measured values of the locating quality which can reflect the whole deformation and the assembly stress distribution of the component can be obtained, based on the optimization of the digital measuring point layout. The placing restrictions of the location hole is analyzed, the optimization model is built to optimizing location hole layout. Based on the unit load response method, the sensitivity matrix of the locating quality is built. The linear relationship between the assembling load at the location hole and the locating deviation, the stress magnitude is matched, and the aim of the assembling load adjustment can be obtained for guiding locating operation. One monolithic reinforced frame is taken to validate this technique, the general theory and method of the flexible precise location of the aeronautical large size monolithic component based on force control technology can be formed.

飞机大型整体结构件由于存在制造差异，加之定位过程中的过约束与强迫定位，造成定位过程管控性差、定位结果难以复现，定位质量不稳定等问题。项目提出基于装配载荷自适应的柔性精准定位概念，即基于飞机大型整体结构件定位质量的数字化测量值，通过分析、计算获得装配载荷自适应调整方案，调整装配载荷达到提高定位精度，降低装配应力的目的。分析定位质量检测要求，量化评价标准，在优化数字化检测点布局的基础上，通过数字化测量获得能反映结构件整体变形及装配应力分布的定位质量数字化测量结果；分析定位孔设置限制，建立优化模型，优化定位孔布局；通过单位载荷响应法建立定位质量敏感度矩阵，基于最小二乘法拟合定位孔处装配载荷与定位偏差、应力大小之间的线性关系，获得各定位孔处装配载荷调整目标，引导定位操作。以某型机后机身整体加强框为例进行试验验证，形成基于力控制的飞机大型整体件柔性精准定位的一般理论和方法。

针对飞机大型整体结构件定位过程管控性差、定位结果难以复现，定位质量不稳定等问题，项目从设计、加工、装配定位与定位质量检测四方面开展了改善性研究。首先，分析工艺孔在结构件加工、装配定位及定位质量检测中承担工艺功能的不同，将其分为定位孔与普通工艺孔两类；以铣削变形最小为目标，针对初始化主定位孔布局，面向加工过程优化普通工艺孔位；利用萤火虫算法优化定位孔孔位，优选出数组加工孔位布局；以单次定位调整变形最小，普通工艺孔凸台处能最大限度反应定位调整变形为标准，加权孔数评价、优选孔位布局，实现了孔位确定从单一工艺过程优化到兼顾产品制造全工艺过程的转变。接着，通过分析大型整体结构件槽腔过渡特征，构建过渡特征线段，准确获取各槽腔加工特征边界和刀具进刀位置；将刀具进刀位置坐标赋予加工元，计算不同槽腔特征之间的空间距离；分别采用遗传算法与蚁群算法对加工工步序列进行优化，合并、排序加工元实现了加工工步的自动决策，加工效率分别比“之字形”走刀路径规划方式降低了13%和19.38%，也有助于加工一致性的改善。最后，结合定位质量检测点坐标偏差值和应力值量化大型整体结构件装配定位质量评价标准，正视定位对象加工差异，基于数字化柔性工装自调功能，通过正交试验法在设计允许范围内设定定位孔孔位，分析定位孔处装配载荷、定位质量检测点处装配应力的变化规律，根据实际定位状态，加权定位偏差得出优选定位孔孔位对应定位孔处装配载荷量值，实现了基于力控制的飞机大型整体件柔性精准定位。