接头定位器在装配型架设计中自动选取的研究与实现

阐述了接头定位器在飞机装配型架装配中的定义和表示的概念,根据飞机装配型架设计的几何约束关系,得到基于几何约束不等式方程组和求解不等式方程组的最优解,并将最优解驱动接头定位器在装配型架设计中自动选取。     

装配型架定位器推理设计技术研究与实现

针对装配型架接头定位器设计步骤繁琐、效率低下等问题,在深入分析接头定位器结构和归纳总结接头定位器类型的基础上,提出并实现了接头定位器推理设计算法以及"紧密-松散"装配约束模式,建立了接头定位器推理设计流程.开发了基于CATIA平台的接头定位器推理设计系统,提高了定位器设计效率,缩短了设计周期,取得了良好的效果.     

基于Abaqus的复杂飞机装配型架有限元仿真技术研究

装配型架是飞机零部件装配过程中不可或缺的关键工艺装备,其刚度和强度直接影响着飞机零部件的装配精度。然而,飞机零部件装配的复杂性导致型架承载情况不明确,致使设计分析人员难以准确评估型架的装配性能,因此急需一种契合飞机零部件装配过程的型架计算方法以提升型架刚强度计算的准确性。针对型架的强度和刚度计算问题,以飞机部件装配过程为例,从型架几何模型的简化、结构力系的离散和边界条件的离散对型架有限元模型的建立进行了梳理,探究了目前常用的常规型架计算方法。为提升型架计算的准确性,基于飞机部件建立了更贴合飞机装配过程的型架计算模型。根据含有飞机部件的型架计算结果,对比分析了常规型架计算的可靠性和稳定性。结果表明,通过常规型架计算方法求得的刚强度计算结果能够简单评估飞机装配型架的刚度和强度,但具有一定的保守性,使得型架设计安全裕度较大,难以契合高效低成本的设计理念。研究结果为复杂飞机装配型架的有限元计算提供了指导。     

基于参数化的飞机装配型架有限元分析方法

装配型架的刚度对飞机装配品质具有重要影响.在深入分析型架结构的基础上,结合型架结构离散化原则和力系约束以及边界条件的简化,将参数化设计技术与型架分析相结合,提出了一种参数化的型架有限元分析方法.利用有限元软件MSC.Patran提供的PCL语言,将参数化设计与有限元分析相结合,自动生成分析模型并完成型架有限元结构分析,大大提高了型架分析的效率.     

基于参数化的飞机装配型架有限元分析方法

装配型架的刚度对飞机装配品质具有重要影响。在深入分析型架结构的基础上,结合型架结构离散化原则和力系约束以及边界条件的简化,将参数化设计技术与型架分析相结合,提出了一种参数化的型架有限元分析方法。利用有限元软件MSC．Patran提供的PCL语言,将参数化设计与有限元分析相结合,自动生成分析模型并完成型架有限元结构分析,大大提高了型架分析的效率。     

飞机大部件对接机构驱动分析与优选

飞机大部件对接装配一般通过多个定位器协调运动来实现,由于支撑需求,定位器存在驱动冗余,驱动方式存在多个方案,需要对不同方案进行分析和优选。文章分析定位器的空间布置和驱动方式对装配对接精度和效率的影响,将对接系统抽象为对接并联机构,采用螺旋理论分析了不同定位器布置和驱动方式的运动自由度,计算了不同驱动方式对位姿调整误差的影响。分析和比较了冗余驱动度小于2的几种典型驱动方式,得出了最优方案,为飞机大部件对接装配定位器的设计和控制提供了理论基础。     

基于Patran&Nastran飞机装配型架刚度分析模块开发及应用

现行飞机装配型架设计中刚度分析大多数依赖于工程经验,在深入研究型架基础上,基于PatranNastran软件平台,利用PCL语言,开发飞机装配型架刚度分析模块。该模块具有较强针对性,简易实用,设计人员可以根据需求快速转换分析模型,从而极大地提高设计效率,缩短设计周期。通过某装配型架设计分析与应用,表明装配型架分析模块的开发带来了较大的经济效益,取得了良好效果。     

模具装配中求解约束的自由度分析算法

采用符号法求解几何约束，能够避免建立和求解大型非线性约束方程组。基于符号法提出并构造了用于求解模具装配约束的自由度分析算法，能够快速有效地求解装配约束，同时较好的解决装配中的欠约束和过约束问题，更易实现模具装配设计过程中的智能化、自动化。     

基于改进遗传算法的装配序列优化

针对虚拟装配序列规划过程的特点和要求,提出了使用装配体在空间坐标系中的干涉矩阵和添加装配零件的装配方向,装配工具和装配类型等约束信息的基因组片相结合的方法,通过几何约束和工艺约束,排除不可行的装配序列,缩小解空间,使算法快速收敛,实现最优序列,最后通过马铃薯种植覆膜机的减速器进行实例验证。     

计算机辅助几何可行装配顺序推理及其优化分析

针对装配优先关系分析、几何可行装配顺序推理以及最优几何可行装配顺序选择3个层次的问题,提出了一种系统化的分析方法——几何约束分析方法。该方法从装配体中各个零件之间的约束方向分析出发,可以自动求解出正确和完备的装配优先关系在装配优先关系的约束下,可以计算出所有的几何可行装配顺序规划;并从操作空间大、装配方便角度出发,设计出几何可行装配顺序优选算法,可以从大量的几何可行装配顺序中求解出几何性能最佳的装配顺序规划。应用具体实例分析演示了几何约束分析方法在计算机中的实现过程,并证实了该方法的实用性和有效性。     

FLEXIBLE ASSEMBLY FIXTURING LAYOUT MODELING AND OPTIMIZATION BASED ON GENETIC ALGORITHM

There are many welding fixture layout design problems of flexible parts in body-in-white assembly process, which directly cause body assemble variation. The fixture layout design quality is mainly influenced by the position and quantity of fixture locators and clamps. A general analysis model of flexible assembles deformation caused by fixture is set up based on "N-2-1" locating principle, in which the locator and clamper are treated as the same fixture layout elements. An analysis model for the flexible part deformation in fixturing is set up in order to obtain the optimization object function and constraints accordingly. The final fixture element layout could be obtained through global optimal research by using improved genetic algorithm, which effectively decreases fixture elements layout influence on flexible assembles deformation.     

Multi-objective optimization design of a fixture layout considering locator displacement and force–deformation

The fixture determines the workpiece position in a machining process; therefore, an increasing amount of attention has been given to fixture layout design. While machining, the workpiece position is affected by two major sources: (a) the locator displacement and (b) the force–deformation of the workpiece–fixture system. In the beginning of this paper, a geometric model considering the shape of a locator is developed to analyze the location performance, followed by the presentation of a simplified solving method and a location layout performance index. Second, to complete the force–deformation analysis, a finite element method-based force–deformation model is built and accelerated by a new method with a lower computer memory cost. Based on these two models, multiple objects of fixture layout optimization problems are proposed, and a multi-objective genetic algorithm-based optimization method is constructed. Finally, testing examples are approved to examine the validity of the method represented in this paper. These methods can provide a more accurate prediction of the locating performance in more widely used cases, and they have faster calculating speeds with lower computer memory costs.     

LOCATORS OPTIMIZATION FOR MEASURING FIXTURE DESIGN

"N-2-1" principle is widely recognized in the fixture design for deformable sheet metal workpieces, where N, the locators on primary datum, is the key to sheet metal fixture design. However, little research is done on how to determine the positions and the number of N locators. In practice, the N locators are frequently designed from experience, which is often unsatisfactory for achieving the precision requirement in fixture design. A new method to lay out the N locators for measuring fixture of deformable sheet metal workpiece is presented, given the fixed number of N. Finite-element method is used to model and analysis the deformation of different locator layouts. A knowledge based genetic algorithm (KBGA) is applied to identify the optimum locator layout for measuring fixture design. An example of a door outer is used to verify the optimization approach.     

基于灰数逼近理想解排序法的夹具设计方案评价

夹具设计的优劣直接影响着工件的质量和精度。分析了定位基准的选择方法,构造了定位基准指标因子表达式,并建立了定位方案层次结构模型。在此基础上,建立了基于约束自由度因子、加工刚度因子和工艺成本因子等指标的夹紧方案评价模型。采用灰数逼近理想解排序法方法对定位方案进行了评价,并利用其评价结果对夹紧方案进行了评价。最后,通过实例验证了所提方法的可行性并确立了最优夹具设计方案。     

组合夹具设计的几何原理

提出孔系基础板组合夹具设计的系统方法。该方法利用连杆机构原理自动确定由直线和圆弧组成定位边界的零件的全部候选定位方案。根据３个定位销和工件轮廓边界的几何关系，提出将工件装卸运动分为平移装卸运动和旋转装卸运动两种运动形式，并提出定位销可见锥概念和定位销转动支点概念，进行定位方案的装卸可行性分析和定位质量分析。根据对３个定位销的反作用力之间的几何和力学分析，进一步提出瞬心三角形概念和同向边概念，并利用这些概念进行工件的可夹紧性分析，确定工件边界的可行夹紧边范围。     

基于变动几何的机床夹具误差预测

将变动几何约束网络应用于夹具误差预测.提出一种针对夹具的变动几何约束网络的建立方法;给出公差向变动几何旋量矩阵的映射关系,以及旋量参数约束式,依据约束式采用极值法计算夹具误差.最后用实例验证方法的有效性.     

Computer-Aided Fixture Design Verification. Part 2. Tolerance Analysis

Tolerance analysis is the most important issue in computer-aided fixture design (CAFD), and it is an important part of computer-aided fixture design verification (CAFDV). This study presents a new approach for fixture tolerance analysis that is more generalised and can be used to assign locator tolerances based on machining surface tolerance requirements. The tolerance analysis is also generalised to handle any type of fixture design, workpiece, datum feature, and machining feature tolerance. Locator tolerance assignment distributes tolerances to locators based on a sensitivity analysis.     

飞机型架设计中流程导航技术的研究与应用

对飞机型架设计流程进行了提炼与划分,明确了各个设计阶段之间的关系.在此基础上,提出了基于CATIA平台的飞机型架设计流程导航技术,将飞机型架设计的知识、规则、经验等融合到系统中,提高了飞机型架设计效率,实现了飞机型架设计的模块化和自动化.     

A Clamping Design Approach for Automated Fixture Design

In this paper, an innovative clamping design approach is described in the context of computer-aided fixture design activities. The clamping design approach involves identification of clamping surfaces and clamp points on a given workpiece. This approach can be applied in conjunction with a locator design approach to hold and support the workpiece during machining and to position the workpiece correctly with respect to the cutting tool. Detailed steps are given for automated clamp design. Geometric reasoning techniques are used to determine feasible clamp faces and positions. The required inputs include CAD model specifications, features identified onthe finished workpiece, locator points and elements.     

A setup planning methodology for prismatic parts considering fixturing aspects

Setup planning is an important part of process planning that has been widely investigated by various researchers. However, the output of the traditional setup planning approaches is limited and insufficient for the upstream process planning activity, fixture design. In this work, a setup planning system is developed that provides sufficient inputs to the fixture designer in terms of recommended depth of cut and feed, fuzzy clamping forces, near optimal locator and clamp layout, and sizes of the locators and clamps. The fixture designer can further optimize the fixture plan by taking these inputs. The methodology is illustrated with the help of an example.