【作者】 王匀；

【导师】 刘全坤；

【作者基本信息】 燕山大学 ， 材料加工工程， 2003， 博士

【摘要】 大型铝型材整体壁板（以下简称壁板、型材），和装配式铆接结构或焊接结构相比，具有比强度高、造型美观、耐腐蚀性和气密性好等优点。随着交通运输的高速化、节能降耗、减轻环境污染等要求的日益高涨，研制挤压壁板作为车厢地板、壁板、顶板等结构件就愈加重要。但壁板具有断面宽高比大(50～100以上)、形状复杂、精度高、壁薄、以及外形轮廓与长度尺寸大等特点，该特点对挤压工艺和模具提出了更高的要求，一般需要在大型挤压机上采用扁挤压筒才能生产。到目前为止，国内大型扁挤压筒的正确设计与制造技术问题一直没有得到很好的解决。本文以扁挤压筒为研究对象，开展大型整体壁板挤压用扁挤压筒强度分析与设计方法研究，对于提高大型壁板挤压模具的设计水平和产品质量，减少进口，实现这类挤压产品的国产化，都具有极其重要的意义。本文在吸纳国内外先进技术的基础上，综合运用理论分析、数值模拟和物理模拟相结合的方法，对壁板挤压模具强度、变形、结构优化和CAD系统进行了深入的研究和实验验证，取得了有实际意义的重要结论和创新性成果。首先系统研究了有限元模拟扁挤压筒的关键技术，为后续的数值分析提供了技术条件。在此基础上，应用接触单元和耦合方法，对组合式圆挤压筒和扁挤压筒进行了数值模拟。建立了预紧圆挤压筒有限元分析模型，通过和理论解的比较论证了接触单元法模拟过盈装配的可行性。在分析组合圆挤压筒的基础上，建立了预紧作用组合扁挤压筒的实体和平面有限元分析模型，并分别考虑了扁挤压筒单独受内压力、预紧力和热载荷以及相互耦合作用的受力情况，获得了接触应力和接触变形分布、等效应力分布、应力集中区以及产生原因。为了建立有实际意义的扁挤压筒应力解析解，本文结合单连体复变函数保角映射法和留数定理推导出受内压力作用的扁挤压筒的应力求解公式，更正了国外文献中相应公式的错误，开发了受内压扁挤压筒的应力计算程序，实现了应力计算的程序化。和数值模拟解的比较表明该方法的正确性，克服了保角映射法应用于扁挤压筒实际工程应力计算的主要障碍，为模具强度设计提供了计算手段。利用建立的有限元模型，探讨了扁挤压筒内腔位移分布情况和内孔变形规律，提出了变过盈量设计的概念，并对缝隙度Km对内孔长短轴变形的影响作了分析，得出Km的取值范围。在此基础上，提出变过盈量的施加和检验条件，以达到等强度设计；还建立了“CAE—数据处理—变形曲线拟合—CAM—检验精度”的修模新流程，为扁挤压筒修模、装配和结构优化提供了依据。 <WP=5>提出了椭圆度概念下的扁挤压筒结构优化思想。通过对不同椭圆度下的数值模拟结果比较，指出了降低不均匀度的椭圆度取值范围，分析了采用椭圆形加强套的可行性。根据椭圆度和扁挤压筒内孔变形特点，建立了扁挤压筒结构优化数学模型，结合增广乘子法和FEM实现了扁挤压筒的结构优化，得出最佳椭圆度和过盈量分配，解决了等强度设计的关键技术问题。为了研究作用于扁挤压筒内壁的内压力分布规律，进行了光弹性实验，并分析了不同截面上的径向和周向应力分布规律。最后将所有有关的扁挤压筒设计经验整合到壁板挤压模具CAD系统，提出了基于RDBMS和FNN的壁板挤压模具ICAD系统，设计并构造了系统框架。系统引入消息触发主控机制，基于OOP的智能推理机和基于关系型数据库的事实库与知识库，同时利用ActiveX Automation技术实现了与CAD的无缝集成。为了解决壁板挤压模具CAD专家系统关于特征识别的前处理瓶颈，本文针对铝型材整体壁板的外形特征和设计要求，构建出壁板特征矩阵和目标矩阵。并采用神经网络分别对带与不带噪声的整体壁板特征识别进行了研究、训练和测试，论证了矩阵构造的神经网络在壁板特征识别中应用的可行性。本文的研究结果，可以为扁挤压筒设计、优化和模型的建立提供技术帮助，对于完善壁板挤压模具设计理论具有指导意义。更多还原

【Abstract】 Compared with riveted and welded structures, the over-all aluminum wallboard profiles (wallboard or profile in short term), have the advantages of high strength/density ratio, fine airtightness and reliable properties, being widely used in ship, traffic and special containers etc. However, because of great width/height ratio (above 50~100), shape complexity, high precision, and large dimensions of the wallboard, it is recommended that the profiles be extruded by the flat receptacle in large extruder. By far, the design and manufacture technology of the flat receptacle have not been pleasingly solved. Therefore, it is important to work on the strength analysis and design method of the flat receptacle for large profiles. Furthermore, the work can reduce the import of extrusion dies for large profiles and improve the quality of extrusion dies.With theoretical analysis, numerical simulation and physical simulation, the strength, deformation, optimization and CAD system of extruding profile die are investigated and verified on experiment. Then, some important and practical conclusions and achievement are obtained.Firstly, the key technology of numerical simulation theory is discussed to offer the technique support to subsequent analysis. Then, the numerical simulations for cylindrical and the flat receptacles are made by contact element and coupling method. The FEA model of prestressed cylindrical receptacle is built, and it shows contact element can be applied to simulate shrink-fit by the comparison with theoretical solution. After that, the planar and 3D FEA models of prestressed flat receptacle are built. Moreover, the flat receptacles under the conditions of pressure, prestress, thermal load and their coupling load are simulated respectively, and get the corresponding results and causes.In order to get the stress analytic solution, the stress equations are deduced with conformal mapping method and residue theorem, the defaults of equations in the reference are corrected. This method overthrows the obstacle in the engineering stress calculation for the flat receptacle with conformal mapping. In this paper, the stress calculation of pressed flat receptacle is developed.Using the established FE model, the deformation Law and displacement distribution of the flat receptacle are researched. Then, the concept of changeable shrinkage (CS) <WP=7>design is initialized. After analyzing the influence of gap ration (Km) on the deformation of major and minor axis, the Km span is obtained. During analysis, the implement and verification of CS are presented, the new die-repair process, CAE-----data processing----deformation curves fitting---CAM---accuracy test, is established. These results give support to mold repair, design of shrink-fitting and structural optimization.The structure optimization for the flat receptacle under the condition of ellipticity is proposed. By comparing with the numerical results of different ellipticity, the ellipticity span to reduce the unevenness is got. The feasibility of elliptical inner layer is also got. According to the characteristics of ellipticity and deformation of the flat receptacle inner-hole, the model for structure optimization of the flat receptacle is built combined with FEM and argumented multiplier method, the structure of the flat receptacle is optimized, and the optimal ellipticity and shrinkage are obtained.The Law for the axial, radial and tangential stresses along the flat receptacle sidewall is obtained by photoelastic experiment.Finally, all the design experiences are introduced into mould CAD system. The CAD system and its framework for profiles have been built based on RDBMS and neural net. In this system, message trigger control mechanism, the fact base and knowledge base based on RDBMS, and the intelligent inference engine based on OOP are introduced respectively. Using the ActiveX Automation technology, CAD can be seamlessly integrated. Furthermore, the bottleneck of preprocessing occurring in extrusion die CAD expert system for wallboard can be solved更多还原