虚拟轴机床模块化设计CAD系统

考虑到虑拟轴机床结构简单、易于模块化设计的特点 ,该系统在虚拟轴机床的设计中引进模块化设计的思想 ,并采用面向对象思想进行虚拟轴机床主要参数及加工空间的计算和三维实体模块库的建立 ,使该系统具有自动化程度高及可扩充的特点 ,大幅度地提高设计效率 ,降低设计与生产成本 ,有利于虚拟轴机床的推广应用     

Development of a die design system for die casting

This paper presents a research work of a computer-aided die design system for die casting. The proposed system consists of seven distinct modules. Through these modules, the die designers are able to create a die casting die from a product part model. It is a user-friendly system that allows both experienced and novice die designers to easily accomplish the task of die design.The practical goal of this research is twofold: (1) to develop a system that integrates the different stages of die design process and (2) that at the same time facilitates the editing of die casting design during or after the course of the design process. The approach undertaken in this research includes (1) feature-based and constraint-based modelling, (2) parametric design and (3) a geometric and topological information extraction technique from a B-rep model. A prototype system has been developed using this approach and the system is able to aid the automation of the die casting die design process, thus improving the efficiency and quality of, and reducing the cost of die design for die casting.     

SPARK,a kernel of software programs for spatial reconstruction in electron microscopy

SPARK, an acronym for ‘SPAtial Reconstruction Kernel’, is the nucleus of a software library being developed for the three-dimensional (3-D) reconstruction of objects observed by the electron microscope. A unifying concept is used: the Fourier transform, known in several central sections, is resampled to obtain a 3-D Cartesian grid, which is inverted by a fast Fourier transform. This technique is used for both single-axis tilting (of 2-D periodic layers or of isolated objects) and for the random conical-tilt technique. The principles that make it possible to recover Cartesian grids in the two different geometries are illustrated and some preliminary results are reported. SPARK resamples the Cartesian grids with the use of a fast and efficient algorithm of Shannon interpolation developed by the authors. Compared to back-projection techniques the method shows a considerable improvement in execution time with no sacrifice in accuracy; it therefore allows the effects of a variety of parameters in a given reconstruction to be scrutinized in a reasonable time. Some new possibilities and future extensions of the library are briefly outlined.     

基于LabVIEW的P-Q阀性能测试

P-Q阀是一种能对执行元件的运动速度及输出压力进行控制的新型双比例控制复合节能阀。P-Q阀组成元件数量少且整体结构尺寸小,从而简化了液压控制系统,所以在各行业中的应用越来越广泛。P-Q阀的性能直接影响到工作系统的可靠性,因此有必要对其性能参数进行测试。简略介绍了P-Q阀测试原理,然后分析了其测试方法,对阀的输入压力、输出压力、输出流量等相关参数进行测试,得出其相应的性能参数及性能曲线,来判断阀的性能是否达到相关标准的要求。     

基于SolidWorks的中小孔数控内圆磨床参数化设计方法的研究

利用VisualBasic和SolidWorks作为开发工具,开发一种基于SolidWorks的中小孔数控内圆磨床参数化设计方法。阐述了这种参数化模板设计方法,包括中小孔数控内圆磨床功能模块划分、模块结构尺寸设计参数分类、模块零部件间关联参数的处理方法、三维模板库的建立等,运用模块参数化设计方法构建了一个中小孔数控内圆磨床模块库。     

基于产品质量的注塑模浇注系统设计

浇注系统设计是注塑模具结构设计中的核心组成部分,其几何形状及结构尺寸设计得合理与否,直接影响塑件成型质量和模具整体结构设计。通过阐述注塑模浇注系统的设计要点,从浇注系统的基本构成（主流道、分流道、浇口、冷料穴）着手分析了其功能,归纳了导致产品产生质量缺陷的原因,主要探讨浇注系统设计技术、方法及应用,在结合理论分析和经验总结的基础上,给出设计推荐参数和设计原则。     

基于实例推理的数控刀具智能化设计的研究及应用

文中根据数控刀具的设计特点 ,建立了基于实例推理的数控刀具智能化设计系统。该系统由数控刀具的实例库和建立在实例库基础上的编码匹配推理机制构成。实例库的建立采用编码对应设计参数的模式 ,从而避免了图形库的存储 ,既节约存储空间 ,又可以加快实例的匹配检索速度     

CAID材质设计子系统的研究与实现

讨论了针对不同情况的两种材质设计方法 :基于色光和基于纹理映射 ,并开发了相应的材质设计子系统。前者利用不同材质的物体对光具有不同的反射、折射特性 ,用参数来描述物体材质 ;后者针对具有纹理、凸凹等特性的材质 ,采用纹理映射来处理。对凸凹纹理的产生、纹理的控制等关键技术进行了详细讨论 ,提出了中间框架的概念。基于关系 -对象数据库建立了材质库和纹理库。实践证明 ,该系统能有效地辅助工业设计师进行材质设计     

Tolerance design of robot parameters using Taguchi method

A robotic arm must be able to manipulate objects with high accuracy and repeatability. As with every physical system, there are number of noise factors cause uncertainty in the performance. A probabilistic approach has been used to model, the otherwise difficult to model, noise effects. This paper presents the approach utilised in selection of tolerance specification of robot kinematic and dynamic parameters using experimental design technique for reduction of performance variations. The concept of inner and outer orthogonal arrays proposed by Taguchi is employed to identify the significant parameters and select the optimal tolerance range. The performance measure, i.e. signal-to-noise ratio is utilised to validate by Monte Carlo simulations and to complement above study individual parameter tolerance sensitivity are investigated. To provide insight to investigation, parameter sensitivity maps are plotted. The tolerance specification selection methodology of a manipulator is illustrated by taking 2-DOF RR planar manipulator with payload.     

A computational system for process design of injection moulding: Combining a blackboard-based expert system and a case-based reasoning approach

Process design of injection moulding involves the selection of the injection moulding machine, mould design, production scheduling, cost estimation, and determination of injection moulding parameters. An expert system approach has been used to derive the process solution for injection moulding over the past few years. However, this approach is found to be incapable of determining the injection moulding parameters owing to the fragile nature of the knowledge for setting the moulding parameters. In addition, the existing expert systems for process design lack proper architecture for organising heterogeneous knowledge sources. In this paper, the combination of a blackboard-based expert system and a case-based reasoning approach is introduced to eliminate the deficiency of the existing expert-system approach to process design, from which a computational system for the process design of injection moulding, named CSPD, has been developed. CSPD first derives the process solution including the selection of the injection moulding machine and the mould base, tooling cost, processing cost estimation, and production scheduling based on the blackboard-based expert-system approach. It is then followed by the determination of the injection moulding parameters based on the case-based reasoning approach and the previously derived partial solution.     

基于UG和Moldflow的手机壳注塑模具优化设计

针对注塑模具设计过程复杂、生产周期长、质量难以保证的不足,在手机壳模具设计过程中应用三维设计软件和有限元分析软件,创建手机壳的实体模型及其型腔的有限元模型。通过对模具注射过程的模流仿真分析,发现浇注系统和注塑工艺参数是实际生产过程中产生质量不足的主要原因,并以此对模具结构进行优化,从而缩短模具生产周期,提高产品质量。     

Geometry-oriented knowledge-based system for preliminary process design of cold-forged parts

This paper presents an integrated architecture of a geometry-oriented knowledge-based process-design system (GEOPDE) for multistage cold forging of solid and hollow parts. It deals with the unit processes of upsetting, forward extrusion, backward extrusion and with combinations of these processes. By using the notion of group technology, the forging processes and forging part geometries are classified. With Prolog as the building tool, the inherited backward chaining reasoning was used for solving the deduction problems. The formation approach, such as “generate and test” and backtracking control strategy, was also employed for generating weighted alternative process plans. Using design rules, empirical formulae and material properties as integrated knowledge, the billet dimensions and the forging sequences are generated automatically once the product dimensions are given by the user. The developed system is a prototype expert system for the preliminary process design of cold-forged products for the forging industry.     

基于Pro/E压铸模浇注系统零件库的构建研究

分析研究了采用Pro/E族表功能构建压铸模浇注系统零件库的方法,并利用族表功能创建了典型卧式压铸机模具的浇注系统零件库,以便在压铸模设计过程中直接调用该浇注系统零件库中的相应零件。这种方法有效地提高了压铸模具设计的效率和质量,具有很好的实用价值和推广效应。     

铸件浇注系统设计数据库软件的开发

介绍了一个计算机软件系统（包括软件开发平台和软件的结构）。系统主要由人机接口模块、数据库数据查询模块，浇注系统计算模块和结果输出模块4部分组成；围绕浇注工艺，讨论了浇注系统的类型和阻流组元之间的比例关系，并进行了系统的计算；最后介绍了系统特点，部分源程序和应用效果。     

工业机器人机械本体模块化设计

基于工业机器人机械本体模块化设计思想,以机器人的结构功能分解为基础,创建了标准机械结构模块库并实现了模块的自动装配。将人体手臂参数作为标准结构模块缩放的内置参数,建立了尺寸不同、功能相似的扩展结构模块库。基于边界曲线的几何特征对工作空间进行了类型划分,并依据关键点位置分析法及改进的CAD变量几何法将工作空间求解模块化。将坐标系模块库生成的D-H参数作为各模块的共享数据,实现了运动学与工作空间的自动求解。以库卡机器人KR6-2的正运动学与工作空间模块化自主求解为例,对比分析软件运行结果与理论计算结果,验证了该方法可满足机器人柔性化自主设计需求。     

磁芯模具的参数化设计及压制模拟

论述了在AutoCAD平台上开发磁芯模具设计系统时的模块设计、模具零件图全参数化设十的方法以及压制模拟算法。     

Design justification of manufacturing systems—a review

The development of design systems which ensure economic feasibility has been the focus of recent research in the manufacturing area. Traditional design and justification approaches have been cited as having shortcomings; thus, there have been a variety of modifications and enhancements developed. An approach that is conceptually different from the traditional approaches seeks the integration of the economic analysis within the design process. We denote this approach as thedesign justification method. This paper reviews literature related to the explicit and implicit integration of economic factors in the manufacturing system design process, followed by supporting issues for the implementation of the design justification concept.     

A gradient-based decomposition approach to optimize pressure path and counterpunch action in Y-shaped tube hydroforming operations

In tube hydroforming, the concurrent actions of pressurized fluid and mechanical feeding allows obtaining tube shapes characterized by complex geometries such as different diameters sections and/or bulged zones. Main process parameters are material feeding history (i.e., the punches velocity history), internal pressure path during the process, and (in T- or Y-shaped tube hydroforming) counterpunch action. What is crucial, in such processes, is the proper design of operative parameters aimed to avoid defects (for instance underfilling or ductile fractures). Actually, the design of tube hydroforming operations is mainly aimed to prevent bursting or buckling occurrence and such issues can be pursued only if a proper control of process parameters is performed. In this paper, a design procedure for Y-shaped tube hydroforming operations was developed. The aim of the presented approach is to calibrate both internal pressure history during the process and counterpunch action in order to reach a sound final component. The approach utilized to optimize the aforementioned parameters is founded on gradient-based techniques and the optimization problem here addressed depends on a considerable number of design variables. In order to reduce the total number of numerical simulations/experiments necessary to reach the optimal values of the design variables, the basic idea of this paper is to develop a sort of decomposition approach aimed to take into account subsets of design variables in the most effective way. The proposed decomposition approach allows avoiding about 50% of the numerical simulations necessary to solve the same problem by traditional gradient technique.     

Stress fields in a compressed unconstrained elastomeric O-ring seal and a comparison of computer predictions and experimental results

A finite element stress analysis computer program, FEMALES (an acronym for Finite Element Mechanical Analysis of Large Elastic Strain), has been written at the University of Bologna, Italy. It was developed specifically for the analysis of large deformations in elastomeric materials. In this paper the program is reviewed for use in elastomeric sealing applications. The principle of operation of the program is described, and its performance is compared with experimental and analytical results for the case of an O-ring compressed between flat plates. The comparison is divided into two parts: a comparison of stress-related parameters and a comparison of displacement-related parameters. Also, two main methods for specifying elastic material properties are considered: firstly an elaborate method which involves a range of measurements from elastomer specimens, and secondly another known as the neo-Hookean model which only requires estimates of Young's modulus and the bulk modulus. In this particular application it was found that the two models gave similar results. This supports the use of the simpler model, since the materials data can be very readily obtained. The overall conclusion drawn from the work was that FEMALES is a workable system that produces results in good agreement with experiment. This gives confidence in its use and development for more complicated geometries, and as such it should become a useful tool for seal design and assessment.     

Integrating mechanism synthesis and topological optimization technique for stiffness-oriented design of a three degrees-of-freedom flexure-based parallel mechanism

This paper introduces a new design approach to synthesize multiple degrees-of-freedom (DOF) flexure-based parallel mechanism (FPM). Termed as an integrated design approach, it is a systematic design methodology, which integrates both classical mechanism synthesis and modern topology optimization technique, to deliver an optimized multi-DOF FPM. This design approach is separated into two levels. At sub-chain level, a novel topology optimization technique, which uses the classical linkage mechanisms as DNA seeds, is used to synthesize the compliant joints or limbs. At configuration level, the optimal compliant joints are used to form the parallel limbs of the multi-DOF FPM and another stage of optimization was conducted to determine the optimal space distribution between these compliant joints so as to generate a multi-DOF FPM with optimized stiffness characteristic. In this paper, the design of a 3-DOF planar motion FPM was used to demonstrate the effectiveness and accuracy of this proposed design approach.