盘套类零件铸造毛坯及工序模型自动生成方法

针对盘套类零件三维工序模型构建问题，提出一种盘套类零件铸造毛坯模型和工序模型自动生成方法。首先将零件设计模型转化为包含候选分割面序列和加工方法链等信息的集成信息模型；然后对设计模型的最小包围盒添加机加余量生成初始毛坯模型，并通过布尔运算获得材料移除体；将材料移除体分割为单元体，对各单元体执行映射和分类操作，获得铸造单元体和机加单元体；最终通过机加余量分离及加工特征映射等操作，生成铸造毛坯模型和工序模型。以典型盘套类零件为案例对所提方法的有效性进行了验证。     

基于加工特征的铸造毛坯生成与合理化

针对现有的CAPP研究很少涉及到铸造毛坯的设计问题,且一般毛坯模型的生成过程比较简单,甚至常常忽略铸造工艺对铸造毛坯制造的要求.以某齿轮箱生产企业的齿轮箱下体箱零件为例,基于该零件的加工特征,在毛坯初始尺寸计算的基础上,将铸造工艺知识引入到CAPP的工艺决策过程,生成初始毛坯的合理化尺寸,并进行合理化修改.同时,对生成的零件加工特征文件进行直接操作,方便快捷地生成合理化的毛坯特征文件,有力地支持了铸造毛坯的设计,实现了CAPP向铸造毛坯领域的有效拓展.     

基于毛坯模型的自动工艺规划

针对大多数现有CAD／CAM系统还不能自动获取并处理尺寸公差、形位公差、表面粗糙度等制造信息，在完成产品设计后无法自动生成相应工艺规划的现状，着重研究对零件设计模型补偿面、体加工特征自动生成毛坯模型后，基于毛坯模型自动提取面、体制造特征的工艺约束信息参数，毛坯模型总体信息参数，结合制造资源数据库、工艺知识库完成工艺规划。将毛坯模型逆变换为设计模型，实现了加工工序过程的拟实验证。     

三维机加工工艺工序间模型快速创建方法

为达到机加工零件快速工艺设计的目的,对快速创建工序间模型的方法进行了研究。根据机加工零件模型加工特征的生成方式及特点,将加工特征分为凹陷特征、凸起特征和过渡特征;以特征识别技术为基础、特征面组为研究对象,结合工艺知识识别出所需加工特征的面组;运用半空间思想及基本建模方法,获取制造特征体并保存;获取所有制造特征体后生成零件毛坯模型,与获取的制造特征体进行布尔操作,快速创建工序间模型。以某机加工零件为例,对该算法进行了实例验证。     

毛坯模型的自动形成技术研究

以铸造毛坯为研究对象，进行了毛坯模型的自动形成技术的研究。首先建立零件的三维特征模型，再提取相关工艺信息，从面加工特征和体加工特征两方面进行加工特征的识别，然后根据相关铸造毛坯知识模型补偿，最终形成毛坯模型。     

零件的设计模型向毛坯模型转换技术研究

为了实现CAD／CAPP／CAM的集成，提出了一种由设计模型向毛坯模型转换、进而向制造模型转换的思想。文章重点研究了由设计模型向毛坯模型转换的技术。具体研究了毛坯模型的定义与生成技术，包括毛坯建模、毛坯模型的生成、切削区域的定义、分解性实体几何造型思想，以及结构实体几何特征模型向分解性实体造型的转化。还研究了设计模型向毛坯模型转换的实现方法。给出了实现这一转换的具体步骤为：识别零件表面、余量补偿、体加工面的识别和立体形状的构建、采用半空间法构建被移去的体特征和偏移量补充。     

基于制造特征的三维工序模型构建方法

为了在零件加工过程中能给实现制造毛坯的动态演变,提出了一种基于制造特征的三维工序模型构建方法。首先,提出了一种制造特征库的构建方法,包括制造特征的表达、加工元的表达以及制造特征与加工元关联关系的定义。接下来,基于制造特征库,从零件的几何模型中自动获取制造特征的定位参数和定形参数,然后通过给定的刀具半径和加工余量,实现加工元的定位和实例化,与毛坯做布尔运算,生成三维工序模型。最后,通过实例验证了该方法的有效性和可行性。     

基于CAD技术的法兰26963工艺工装设计

据图纸要求铸造零件毛坯,进行模具设计及制造,分析零件结构特点拟定合理的工艺规程,依据工艺规程选择相应的机床,设计合适的夹具。运用Pro/E软件完成零件的三维实体造型以及模具的开模。确定改零件的加工工艺路线。     

基于STL模型支撑生成算法的研究

针对快速成型制造中须对零件加支撑的需求,提出一种新的支撑生成方法。它首先提取零件待支撑区域的关键特征(如悬吊点、下棱线、待支撑下表面的轮廓线等),同时指出各种支撑的基本构件实质就是单边对应的多边形支撑面,并采用了局部斜板支撑的方案实现其生成算法,在此基础上生成零件的特征支撑;然后采用对生成的特征支撑STL模型分层后分区扫描填充加强支撑线来实现对待支撑下表面内部区域的有效支撑。应用表明：该方法实现了对成型零件关键特征的准确支撑和对待支撑面域的有效支撑,生成支撑效果良好。     

面向制造特征的数控车削系统构架的研究

针对轴类零件的加工特点,定义轴类加工基元,建立了加工基元工序组,并对该工序组进行优化,建立了基于制造特征的数据模型及在该模型上实现的轴零件数控车削系统,建立了以该模型为基础设计制造软件体系。与现有的国内外数控系统相比,该系统CAD功能部分零件图的生成是从选择毛坯开始,零件图的绘制过程就是从毛坯到制件的不断去除材料的布尔运算过程,系统对这些运算过程进行优化,形成CAM部分的加工工序,更符合中国人的绘图习惯。     

A rapid and intelligent approach to design forming shape model for precise manufacturing of flanged part

Adjusting the part shape with complex flanges to compensate springback deformation is key to forming shape design for manufacturing rapidly and precisely. Classical forming shape design by displacement adjustment (DA) method using finite element (FE) simulation is usually time-consuming and not accurate enough for complex surface part in industrial application. In this paper, the forming shape is modeled by changing the relations of geometric features of part model with the new flange control surfaces directly. Control surface processing (CSP) method is presented including control surface trimming, cross section division, springback compensation, and extending to design forming shape model of doubly curved flange part with joggles rapidly. The algorithms of cross section curves division of control surfaces and subsequent subdivision of each curve with circular arc and line segments are proposed. A case-based reasoning (CBR) technique and gray relation analysis (GRA) are used to support the intelligent springback prediction of each bending segment of the cross section curve. The geometric data of control surface is expressed in XML format to realize the integration of the CAD-based tools of control surface division and compensation with the Web-based springback prediction system. The approach is demonstrated on an industrial aircraft wing rib part. The forming shape model could be designed rapidly by comparison with DA method. The part shape deviations of flange angle (?0.465° ~ 0.528°) and surface position (?0.3 mm ~ 0.3 mm) were detected by comparing the desired geometry with the actual digital formed part shape, and the results indicate that the approach can achieve the industrial part manufacturing rapidly and precisely.     

Extraction of manufacturing information from design-by-feature solid model through feature recognition

Feature recognition is the key to the computer-aided design (CAD) and computer-aided manufacturing (CAM) integration to build a computer-integrated manufacturing system. There are two approaches to CAD feature recognition: platform-dependent and platform-independent. In the platform-independent approach, the part’s geometrical data are extracted from a neutral file such as DXF, IGES, or STEP. In contrast, the platform-dependent approach extracts the information of the design features directly from a design-by-feature solid model through the object-oriented model of a part. This paper explains a platform-dependent approach which is implemented to translate design features into manufacturing information. This approach begins with simplification using the suppression of fillets, and clustering non-intersecting design features is done. Then, the rule-based method is employed in order to recognize machining features. Finally, the needed manufacturing information such as tool accessing direction, dimensions, material removal regions, and geometrical and topological data is recognized. The application of the proposed system would be exhibited in generating machine path code for rapid prototyping and CNC machines and providing a database for computer-aided process planning. The proposed system was implemented on Autodesk Inventor and successfully tested for many complex 3D models.     

满足已有制造依据的飞机外形曲面重建原则

在航空企业推广无纸设计、制造技术的第一步,是建立飞机外形的数字化模型。本文详细介绍了某型号飞机在建立符合设计要求,满足已有制造依据的数字化模型过程中应该遵循的原则,即协调关系不变、曲线、曲面原始定义不变、按设计特点构造曲面、参照理论模线设计规定误差。     

面向制造的曲面设计系统

为了支持面向制造的曲面设计,提出了一个基于计算机辅助设计／计算机辅助制造系统的嵌人式计算平台,该计算平台主要包括约束信息建模和可制造性分析2个功能模块。通过对曲面可制造性判据的抽象,建立了应用信息模型,用于从曲面几何形状中提取制造约束信息。应用于曲面加工问题,给出了根据约束信息计算可行刀具方向的具体方法。面向模具零件分型曲面的设计,建立了可制造性分析工具。针对一个雕塑曲面零件设计实例,通过对模具分型方向和加工约束进行分析,给出了可行的分型曲面设计结果,验证了所提出的曲面可制造性分析方法的可行性。     

Tolerance evolutionary model and algorithm in product growth design

To guarantee the successful transformation from product functional requirement to geometry constraints and finally to dimension constraints between components in a product, an evolutionary tolerance design strategy is proposed on the basis of automation technology in product structure design. In the first part of this paper, the theory of the growth design and the process of tolerance evolutionary design are introduced. Following the evolution of product structure, product tolerance grows from its initial state, defined by accuracy requirements, to its final state, defined as dimension tolerance and geometric tolerance. In this growing process, the basic units in the product growth design, known as functional surfaces and their nominal features, are used as evolutionary carriers. With the help of these basic units, the method for the construction of a two-layer correlation network is proposed. In the second part, the tolerance assertions to assist tolerance evolutionary design are given, based on which the basic process for an evolutionary design of dimensions chain and geometric tolerance are presented. In order to optimize the allocation of the dimension tolerance, a mathematical model is developed in which a correlated sensitivity function between the cost and the tolerance is created. In the model, the design cost, the manufacturing cost, the usage cost, and the depreciation cost of the product are used as constraints to the tolerance allocation. Considering these costs, a multifactor cost function to express quality loss of the product is developed and is applied into the model. The minimum cost is used as the objective function, and the depreciation cost in the objective function is expressed by the discount rate—terminology in economics. The aim was to achieve a final and ideal balance around assembly, manufacturing, and usage through the control of product precision. In the last part, the successful usage of the proposed tolerance evolutionary strategy in the incremental growth product design is demonstrated through a design example.     

并行设计系统中的工艺咨询与决策模型

应用模糊理论的思想,提出一种实现计算机辅助工艺咨询的方法,该方法描述了零件功能与零件特征、零件特征与特征的加工方法、特征的加工方法与设备资源之间的映射关系,从而建立了工艺咨询的模型,解决了替代特征、替代加工方法和替代设备资源的咨询问题。     

Design and machining of the epicycloid planet gear of cycloid drives

This paper presents a mathematical model and design procedures to design the epicycloid planet gear of cycloid drives. It is based on coordinate transformation, envelope theory, and theories of conjugate surfaces, from which the equation of meshing is derived, while the path of machining tools is obtained by the equidistant curve principle. In addition, a program is developed to solve the equations of meshing and conjugate surfaces. Therefore, the epicycloid-profile is obtained. Then, these data are used to construct the 2D drawing and solid modeling of the epicycloid-planet-gear using AutoCAD and Pro/E (a CAD software package), respectively. The CAD data is used for machining, in this case by a wire-cutting machine. The manufactured component is presented to demonstrate that the design procedures and manufacturing are feasible. The design approach and machining method are suitable for applying CAD and CAM in industrial fields.     

云制造下设计任务与知识资源双边匹配方法

设计任务与知识资源的匹配大多是以业务流程为基础的单向匹配,为解决研发设计任务与知识资源之间的双边匹配问题,提出面向云制造模式的研发设计任务与知识资源双边匹配总体框架,该框架包括双边匹配满意度评价指标体系构建、多指标满意度评价信息处理和多目标双边匹配决策模型构建与求解等关键步骤。以卫星产品研制工艺知识为例,验证了所提方法在解决设计任务和知识资源双边匹配,以及提升产品设计任务执行效率与质量方面的有效性。     

UG的参数化建模方法及三维零件库的创建

UGNX是美国EDS公司的CAD/CAE/CAM一体化软件,具有强大的参数化设计功能,在设计和制造领域得到了广泛的应用.其参数化功能能够很好反映设计意图,参数化模型易于修改.本文以UGNX为支撑平台,介绍了三维参数化建模的基本思想和实现方法,结合实例分析了三维零件参数化模型的建立步骤,并创建立一个简单的零件库.