基于KBE的汽车覆盖件冲压工艺方案设计

汽车覆盖件的冲压工艺方案设计是一个复杂且经验性强的创造性过程,需要一种支持多种知识表达模式和多智能决策技术的方法,解决工艺方案决策问题.通过以工艺特征为核心来表达知识,建立了基于KBE的覆盖件工艺知识模型,采用基于知识驱动决策树表达模式的特征转换机制来实现设计特征到工艺特征的映射,在工艺知识库的支持下完成工艺方案设计.实现了知识的多种描述形式及其应用,有效地解决了工艺方案设计中基于图形、规则及经验知识的决策判断,提高了汽车覆盖件工艺方案设计的智能化程度.     

基于KBE实施体系的研究

基于知识的工程技术(Knowledge Based Engineering,KBE)是人工智能、CAD系统、计算机软件技术相结合的产物。其在工程设计领域产生了广泛影响,大量应用在航空航天、汽车、船舶等行业,具有广泛的应用前景和发展潜力。本文提出了一种KBE的实施体系和利用拓扑规则处理领域知识的方法。该体系捕捉和重用工程知识,向工程师提供自动化的设计手段。     

汽车覆盖件冲压工艺设计KBE系统中的知识表示技术

根据汽车覆盖件冲压工艺设计的特点,阐述了与汽车覆盖件冲压工艺设计有关的不同类型知识的表示方法,主要有一阶谓词逻辑、语义网络、产生式规则、框架和剧本、可视化文本和图象,以及面向对象的方法等,并比较了各种方法的优缺点.面向对象的集成知识表示等方法成功地应用于汽车覆盖件冲压工艺设计KBE系统的知识表示.     

冲压件结构工艺研究

冲压件具有良好的工艺性和经济性,衡量其水平的重要标志有冲压件的工序数、车身总成的分块数目和尺寸大小、冲压件的结构等因素。针对加工工过程中的设计与加工工艺,做进一步研究。     

数控编程KBE系统的基础性使能技术研究

针对数控编程领域知识的特点,对KBE系统实现的基础性使能技术进行了研究,介绍了基于实例和规则的数控编程领域知识表示方法和知识获取的概念、途径及过程,阐述了CBR在复杂零件数控编程中的应用,提出了以人工知识获取为主、机器学习为辅的数控编程领域知识获取方式和基于双向混合推理控制策略的CBR／RBR集成数控编程领域知识推理方法,研究成果在开发的原型系统中得到了应用,证明方法可行．     

基于KBE技术的机械产品数字化设计

为了提高企业对市场的响应能力,满足用户多样化、个性化的需求,设计者常常需要借鉴一些相似产品的设计范例.为此本文介绍了KBE技术的结构层次,并将其应用到机械产品的设计中去.通过基于知识的数字化建模,在相似产品的基础上设计出可以知识复用的产品模板,从而为设计者提供正确有效的设计工具.     

基于冲压件的Autoform数值模拟分析

论述了椭圆花样冲压件的有限元模拟主要步骤,以椭圆花样冲压件为研究背景,采用Autoform软件对零件进行了冲压成形过程的有限元分析,完成了相关数值模拟,预测了板料成形过程中的缺陷,根据仿真结果对工艺方案再次CAE仿真优化,证明了前期数值分析对模具设计周期及成形质量具有重要意义。     

大型复杂冲压件CAPP的发展趋势

讨论了大型复杂冲压件计算机辅助工艺设计中数值模拟技术的应用、系统模型与工艺决策等关键技术的发展,以及CAPP与相关系统的集成,分析了大型复杂冲压件计算机辅助工艺设计的发展趋势.     

基于KBE的摩托车车架的有限元分析系统的研究

研究了基于 KBE 的摩托车车架有限元分析系统的框架结构,提出了面向对象的知识表达方法和基于实例的推理与基于规则的推理相结合的混合推理机制,并结合摩托车车架设计分析实例进行了试验。     

有限元与田口实验设计中冲压加工模具参数稳健性设计

本文提出了一种稳健的对冲压模具参数设计方法,以V形件冲压过程研究对象,采用有限元仿真软件ABAQUS建立了V形件冲压加工过程仿真模型,并利用田口方法,分析了所有建模因子对仿真模型的稳健性影响,找出最有利于提高模型稳健性的建模因子及水平设置.采用正交实验设计,就模具参数的稳健设计进行了分析,并以试验对本研究方法进行了验证.确认了在现有的仿真实验和试验水平下,本文提出的方法是可行的,结论是合理的.     

Feature-based metal stamping part and process design. Part II: stamping process planning

In metal stamping development, stamping process planning plays quite an important role for the related die design. As mentioned in Part-I [Feature-based metal stamping part and process design. Part 1: stampability evaluation, 2007, 45, 2673–2695], the feature can encapsulate comprehensive engineering information; this paper proposes to realize stamping process planning based on feature mapping. A feature mapping system, between a stamping design feature space and a stamping process feature space, has been presented. The inherent mechanism of such feature mapping has been investigated with formal representations. The substance of feature mapping is the processing of related knowledge and information. Mapping rules are established to generate the stamping operation and stamping direction. Four mapping manners (direct mapping, conjugate mapping, syncretic mapping, and sequential mapping) are presented for generating the form of process feature, through geometrical information transformation from design features. Meanwhile, considering a stamping process plan as an ordered tree, this paper has introduced how to build a stamping process plan through organizing the stamping operations mapped from design features, and an illustrative example is demonstrated.     

Feature-based metal stamping part and process design. Part I: stampability evaluation

It is essential to devise a representation scheme for the metal stamping part design which allows the designer to capture and reason the design information, and ultimately, to take various considerations into account and make evaluation decisions. In our research, the feature-based approach is used to represent the metal stamping part, and feature-based metal stamping part and process design has been studied and presented in a two-part paper. This is the first of a two-part paper focusing on stampability evaluation. In Part II a feature-based stamping process planning approach is investigated. This paper presents a feature- and knowledge-based stampability evaluation system. Tasks of this research include identification of the aims, criteria, and procedure of stampability evaluation, as well as the formalization of the stampability evaluation knowledge. Stampability evaluation is classified into stampability verification and stampability measurement. Stampability verification is used to determine whether a part design is stampable or not. Stampability measurement can be employed to select a best design from stampable candidate designs. Based on the stamping design feature definition, a stampability-coding scheme with incorporated knowledge has been developed to enable comprehensive stampability evaluation. Finally, a case study demonstrates the feasibility of such stampability evaluation system.     

Performance of die cooling system design in hot stamping process

This study examined the cooling channel design of hot stamping tools to provide an effective method for the cooling system design. A flat plate tool model was investigated to determine the effects of cooling channel and manufacturing parameters on the cooling rate and cooling uniformity of the sheet blank by conducting finite element analysis. The fractional factor method was also employed to establish empirical equations for describing the cooling performance of the flat plate model. The empirical equations established in the present study can efficiently predict the cooling rate and cooling uniformity of sheet blanks with various cooling channel designs, and are of much help in providing an initial cooling system design for hot stamping tools. To validate the accuracy of the finite element analysis, experiments on sheet blank cooling process were conducted using the proposed flat plate tool design. The cooling processes were cyclically repeated for the validation of blank temperature distribution. The temperature evolution of sheet blanks obtained from the finite element simulations agree well with the experimental results and the validity of the finite element model is confirmed, and thus the effectiveness of the empirical equations is established.     

基于系统工程过程的维修性设计要求生成过程研究

维修性设计要求的生成是维修性工作的一个重要组成部分,然而目前还没有有效的方法和过程支持该项工作的开展.借鉴系统工程过程的基本步骤,结合产品的一般研制程序,提出维修性设计要求的一体化生成过程,该生成过程包括维修方案的生成、维修性指标的确定与分配、维修性设计要求的生成三个主要工作,并对各项工作过程进行了详细的阐述.     

热压成形在车身上的典型应用与研究

依托于新车型的开发,基于热压成形特性及零部件性能要求,选取某车型B柱加强板进行热压成形技术的可行性分析.通过分析热成形钢的材料及工艺特性,考察采用热成形钢后的B柱加强板侧碰过程中的侵入量、侵入速度、车体加速度以及顶部加压性能的优劣势,提出了结构优化方向,归纳了热压成形技术的关键点.分析结果表明,应用热压车型技术对工程化影响不大,可实现白车身轻量化效果并可大大提升白车身侧碰被动安全性能.     

Die shape design optimization of sheet metal stamping process using meshfree method

A die shape design sensitivity analysis (DSA) and optimization for a sheet metal stamping process is proposed based on a Lagrangian formulation. A hyperelasticity‐based elastoplastic material model is used for the constitutive relation that includes a large deformation effect. The contact condition between a workpiece and a rigid die is imposed through the penalty method with a modified Coulomb friction model. The domain of the workpiece is discretized by a meshfree method. A continuum‐based DSA with respect to the rigid die shape parameter is formulated using a design velocity concept. The die shape perturbation has an effect on structural performance through the contact variational form. The effect of the deformation‐dependent pressure load to the design sensitivity is discussed. It is shown that the design sensitivity equation uses the same tangent stiffness matrix as the response analysis. The linear design sensitivity equation is solved at each converged load step without the need of iteration, which is quite efficient in computation. The accuracy of sensitivity information is compared to that of the finite difference method with an excellent agreement. A die shape design optimization problem is solved to obtain the desired shape of the workpiece to minimize spring‐back effect and to show the feasibility of the proposed method. Copyright © 2001 John Wiley & Sons, Ltd.     

空调用冲压管路件失效机制及结构优化

分析空调用冲压管路件失效机制,通过引用压力容器回转壳体无力矩理论及无力矩理论应用中用以计算椭球壳薄膜应力的方程式,对冲压管路件结构开展优化研究,将冲压管路件结构尺寸参数化、标准化,以提高冲压管路件承受脉冲压力的冲击能力,提高整机质量的可靠性。     

可淬火硼钢板热冲压成形实验研究

为研究淬火加热温度、保温时间及冷却水流速等热冲压工艺参数对热冲压零件力学性能及微观组织的影响规律,通过在不同工艺参数条件下进行弯曲件热冲压工艺试验,测量弯曲件的力学性能并观察其金相组织.结果表明,在所设计的模具上可实现高强硼钢热成形零件的有效淬火,热冲压弯曲件的抗拉强度可达到1500MPa以上,主要形成均匀细小的马氏体组织.确定了热冲压工艺参数的选择范围.     

高强度钢板U形件热冲压凹模结构拓扑优化

为降低热冲压凹模的生产成本和使用成本,基于板料热冲压数值模拟对凹模结构进行了拓扑优化设计.运用有限元软件ABAQUS建立热力耦合有限元模型,对高强钢板U形件的热冲压成形和淬火过程进行了数值仿真.提取凹模与板料间关键工况下接触应力作为凹模拓扑优化的外在载荷,建立约束凹模结构关键区域节点位移的体积最小化拓扑模型,对热冲压凹模结构进行拓扑优化设计,最终实现结构减重20%,且优化后凹模的变形和应力与优化前的结果相差甚微.研究内容对热冲压过程数值模拟和模具结构拓扑优化研究具有一定参考价值.