隔框类航空整体结构件变形校正关键技术研究

Research on key technologies for straightening pocketed aircraft frame parts

针对隔框类整体结构件截面形状复杂,数控加工变形校正操作困难,无法用解析表达式求得校正参数的工程难题,在研究变形校正基本原理的基础上,给出了校正载荷的施加原则.提出了基于反求思想,通过搜索特征曲线拐点确定校正支点位置的方法.进一步研究了基于有限元模拟技术,采用二分法计算校正参数的方法,并分析了不同载荷形式对校正效果的影响.对于复杂弯曲变形零件,在科学确定支点位置和校正载荷形式的基础上,提出了兼顾局部和整体校正质量的分步校正方法,并进行了实例分析.最后给出了工件初始变形量、支点距离与所需要的校正反弯压下位移量的关系曲线,可用于指导隔框类整体结构件的校正生产.

For pocketed aircraft frame parts, due to their complicated cross-section, straightening parameters cannot be expressed as simple analytic expression. The engineering problem of how to choose and apply straightening load can be resolved by research on the straightening theory. A method for determining the support position on the principles of reverse engineering was put forward. The support position was determined by the inflexion point of the distorted part's characteristic curve. FEM (finite element method) revealed that the curve's dichotomy adopted could be used to calculate the straightening load. For a given supporting plan and the type of straightening load, the influence of different kinds of load must be analyzed and the step-by-step method recommended for straightening the deformed parts at various bending points must be followed. Experiments on many samples yielded the experimental curves for initial deformation versus downstroke and for supporting distance versus downstroke. These curves can be used to guide straightening production.