一种孔系组合夹具夹紧装置构形设计方法

介绍一种针对棱柱形工件的孔系组合夹具夹紧装置的自动构形方法。首先确定工件的夹紧区域并离散化,然后根据工件的形状确定夹紧装置的个数,进而确定候选夹紧方案,并提出夹紧方案的质量评价标准。最后通过实例验证上述方法的可行性和精确性。     

孔系组合夹具定位方案通用设计方法

提出一个面向孔系组合夹具的定位方案通用设计方法,该方法的通用性体现在以下几个方面:1)工件的侧面定位 基准可以是平面和圆柱面,以及两者的各种组合。2)定位元件的类型可以是圆柱销和V形块、半V形拼块,以及同一次 装夹中采用不同形式定位元件的混合定位。3)可以进一步扩展到适用于任意曲线柱面作为定位基准。     

A geometrical approach to computer-aided process planning for computer-controlled machine tools

This paper documents part of a research program which has been under way at the CIM Centre at Swinburne University of Technology since 1989. The purpose of the research program was to develop an open-architecture machine tool control system and then to see how that system could be used to change the distribution of traditional manufacturing design, planning and control functions. This paper examines one part of that research program and focuses on a methodology which could prove to be useful in the machine tool selection, cutter selection and cutter path generation phases of process planning for cutting operations on workpieces in computer-controlled machine tools.It is suggested that a configuration space transform be used for each cutter/machine tool combination to find the volume that the combination could remove from the uncut workpiece without removing any of the material that will form the final workpiece. A method of comparing these volumes from different combinations is then outlined. The output of this method is a reasonable sequence of machine tools and cutters. Path planning can then be carried out for each of the chosen combinations using a method similar to the one used to find the possible volume to be removed.Possible implementation techniques, and their limitations on existing computer hardware, are discussed and the most promising of these are identified, based upon some properties of configuration space transforms.     

A model management systems approach to manufacturing systems design

Manufacturing systems design involves the solution of a complex series of interrelated problems. This complexity will increase in the future as manufacturing practices change to meet increased global competition. Research within manufacturing systems design has mainly been focused on finding improved models for solving particular problems, or extending existing modeling techniques. This has resulted in numerous modeling tools being available to support manufacturing systems design. However, little research work has been carried out into consolidating the existing theories and models. As a result, a large body of this work has not been applied in industry.Model management has evolved as a research area which investigates methods for storing, modifying, and manipulating models. This article describes a prototype model management system for manufacturing systems design. The objective here is not to develop another decision support system for manufacturing design, but to illustrate, through the development of a prototype system, a number of key ideas of how concepts from the area of model management systems can be used to support manufacturing systems design. The prototype model management system utilizes the structured modeling framework and uses an extended version of the structured modeling language. An important aspect of the prototype model management system is the incorporation of the model development task, thus allowing the system to be easily updated and adapted. The prototype system was evaluated using a range of queueing network models for manufacturing systems design.     

PDM/CAFD集成技术研究

PDM作为 CAD/CAPP/CAM的集成平台越来越受到人们的重视 ,但其对计算机辅助夹具设计 (CAFD)的支持却很少有人关注。本文在分析了基于 PDM的集成化夹具设计系统体系结构后 ,着重研究了基于 PDM的组合夹具设计模型构建技术 ,并在此模型基础上实现夹具的快速设计和装配 ,以有效地支持并行工程的实施。     

面向并行工程的产品设计生命系统模型探讨

本文探讨了并行工程和生命系统理论与产品设计的联系以及它们是如何提高设计效率的，在此基础上，本文提出产品设计过程模型。该模型从产品需求分析出发，结合生命系统理论，为设计人员有层次、并行地展开设计工作提供了一个概念框架。模型具有开放性，设计人员可以运用多种学科理论和技术进行工作，并多方位地采纳各部门的意见。本文还初步构造了一个用于产品设计建模工具软件的图形系统。     

价值工程与面向成本的设计

价值工程 (VE—ValueEngineering)方法是降低产品成本的常用方法 ,随着并行工程的深入发展 ,面向成本的设计 (DFC -DesignForCost)应运而生 ,它是DFX方法的一个分支。通过VE与DFC两者的分析和对比认为两者既有区别又有联系 ,两者在信息收集、改进设计、研究范畴等方面有相同之处 ,因此在DFC中可以使用价值工程中的情报收集、功能分析、方案创造和评价等方法 ,并给出了这些方法在DFC中的应用环节和途径 ,为DFC与价值工程方法相结合指出了方向。     

Production engineering-oriented virtual factory: a planning cell-based approach to manufacturing systems design

In the traditional process of designing a manufacturing system, a sequential approach treats each of the design steps individually, without considering the requirements of concurrent design activities. The lack of systematic and concurrent consideration of the interactive impact of design decisions leads to repeated and excessive changes in the design and process. To resolve this problem, this research develops a production engineering-oriented virtual factory – a planning cell-based manufacturing systems design approach. The manufacturing systems design process based on a planning cell is reengineered according to the concept of concurrent engineering. The process modeling of a production engineering-oriented virtual factory is proposed at generic and particular levels. An illustrative example of an engine assembly plant demonstrates the effectiveness of the new approach.     

并行工程环境下的飞机工装设计数据管理

论述了飞机工装设计数据管理与产品设计的关系 ,介绍了并行工程环境下的飞机工装设计数据管理系统的体系结构 ,运用 IDEF3建立了过程模型 ,运用 IDEF1X建立了信息模型 ,定义了工装产品数据对象的层次结构 ,介绍了与传统数据管理模式的转换接口设计     

A morphological approach to product design in a concurrent engineering environment

The development of product design in a concurrent engineering environment requires the consideration and inclusion of life cycle factors early in the design process. This paper proposes a product design framework where these factors are considered. The phases of product design in a concurrent engineering environment include: design requirements, design functions, design alternatives, design attributes, and design environments. A five-step algorithm is proposed by which the optimal design alternative, among all the feasible alternatives, is selected. In order to illustrate the proposed framework, the design of a braking system is presented in each phase. A morphological approach to product design is proposed that consists of two related morphologies. Morphology 1 addresses the innovative aspect of product design. Morphology 2 considers the computational and optimisation aspect of product design. In conclusion, an integrated approach which reconciles both morphologies is suggested.     

Interface between CAD and Rapid Prototyping systems. Part 2: LMI — An improved interface

The STL (STereoLithography) file format, as developed by 3D Systems, has been widely used by most Rapid Prototyping (RP) systems and is supported by all major computer-aided design (CAD) systems. However, it is necessary to improve the STL format to meet the development needs of RP technologies. In Part 1, several existing and proposed formats have been discussed. This paper, Part 2, will present an improved interface between CAD and RP systems. The new interface is a file format that supports the STL format, removes redundant information in the STL format and adds topological information to balance storage and processing cost. In addition to supporting facet boundary models, the new interface supports precise models by using the edge-based boundary representation. This paper discusses the design considerations of the new interface and data structures for both facet models and precise models. Finally, a comparison of the new interface and the STL file format will be made.     

A new approach to generation of ruled surfaces and its applications in engineering

Based on the Study displacive theory that there is a one-to-one correspondence between an oriented straight line in three-dimensional Euclidean space (E ³) and a dual point on the surface of a dual unit sphere (DUS) in three-dimensional dual space (D ³), this paper presents a new methodology for the generation of ruled surfaces by planning (fitting or interpolating) the motion locus of a point on the surface of a DUS and discusses its applications in engineering. Some geometric problems and an optimal generation model for ruled surfaces are dealt with in detail. The correctness and effectiveness of this methodology are illustrated by examples and application in practice.     

A mathematical approach to analysis and optimal design of a fixture locating scheme

In manufacturing engineering, localization accuracy is a key concern in the design of a fixture to specify a locating scheme and tolerance allocation. This paper presents a general analysis methodology that is able to characterize the effects of localization source errors based on the position and orientation of the workpiece. From this methodology, a fixture model is formulated by taking into account the overall errors among the system consisting of the workpiece and the fixture in the design of the fixture locating scheme. With this model, the locating principle and a criterion of the robust optimal design are then proposed to improve the localization quality of the fixture. Some examples are provided and allow for a detailed discussion about how to carry out the optimal design of the locating scheme. A comparative study is also made between the optimal solution and the empirical one. Finally, an experiment is made to validate the fixture locating scheme for a cylindrical workpiece. We conclude that this robust design method effectively achieves stable machining precision in workpieces.     

A structured approach to the automatic planning of machining operations for rotational parts based on computer integration of standard design and process data

The traditional procedure for developing a manufacturing process plan involves a number of interconnected steps beginning with the initial design and culminating in the instructions for the machine that makes the part. When performed manually, the procedure is very tedious, time consuming, and often, inconsistent. This paper presents an alternative method, called the Automated Machining-Operations Process-Planning System (AMOPPS), to automatically generate the process plan and the numerical control (NC) instructions to machine a part that has been previously designed by a computer-aided design (CAD) system. AMOPPS combines preset planning logic and data from three databases (viz., workpiece material, machine tool, and cutting tool) with appropriate data from a CAD database and information from the user about the workpiece to calculate the optimal machining parameters, print a process plan, print the corresponding NC program listing, and provide an on-screen animation of the cutting passes. Although AMOPPS is a prototype, it can be extended by adding other modules, and it does provide a structure through which a fully integrated manufacturing system can be developed.     

SMT-TAB: A process planning system for PCB assembly using TAB and SMT

Process planning is a critical function in any manufacturing domain. This is especially true in the electronics manufacturing area where substantial heuristic and experiential knowledge is commonly used during process plan development. While research in computer-aided process planning (CAPP) has tended to concentrate in the machining realm, few CAPP systems have been developed for electronics manufacturing applications and more specifically for the printed circuit board (PCB) assembly domain. Besides, the CAPP systems that have been developed for this area have dealt with either insertion mount or surface mount PCB assembly processes only.Tape automated bonding (TAB), though a relatively new technology, is gaining importance in electronics assembly owing to its inherent advantages. The advent of fine pitch technology together with the ever increasing need for more inputs/outputs and greater pin counts in integrated circuit applications has enhanced the use of TAB technology in electronics manufacturing. This trend has been further augmented by the increasing need for compactness in consumer electronics.This research designed and developed a prototype CAPP system for the PCB assembly domain. The system developed generates a process plan for PCBs populated with surface mount and/or TAB components. An artificial-intelligence based expert system approach has been used in the design and development of the CAPP system. Outputs generated by the system are presented along with ideas for future research.     

先进设计技术在船舶设计中的应用策略

中国加入WT0后，造船企业将面临更激烈的竞争。通过对船舶行业概况的分析，指出我国的造船企业与先进国家的造船企业有如下一些差距：造船产量不够高；技术差距大，高技术产品少；串行设计周期长，质量难以保证，生产效率低；成本偏高；生产模式落后；信息化水平低，信息集成度差。针对所存在的问题，我们认为可以通过实现并行设计、虚拟设计和虚拟企业来提高船舶设计能力，以迎接WTO的挑战。     

A blackboard-based process planning system for the surface mount manufacture of PCBs

This paper describes a real-time computer-aided process planning (CAPP) system for printed circuit board (PCB) assembly using surface mount technology. The prototype, dynamic, realtime CAPP system described uses a blackboard to integrate multiple knowledge sources (knowledge bases) in implementing the process planning procedure. The CAPP system is implemented using the expert system environment (ESE) and structured query language (SQL). The system uses two subsystems (knowledge bases). They are a planning subsystem which performs the static process planning task and a dynamic information processing subsystem which considers the real-time changes on the shop floor and routes the PCB assembly flow. The integrated system developed generates process plans that can be implemented in real time. The use of the blackboard concept for CAPP architecture is unique and well suited for this task.     

A novel approach to delay-fractional-dependent stability criterion for linear systems with interval delay

This paper considers the problem of delay-fractional-dependent stability analysis of linear systems with interval time-varying state delay. By developing a delay variable decomposition approach, both the information of the variable dividing subinterval delay, and the information of the lower and upper bound of delay can be taken into full consideration. Then a new delay-fractional-dependent stability criterion is derived without involving any direct approximation in the time-derivative of the Lyapunov–Krasovskii (LK) functional via some suitable Jensen integral inequalities and convex combination technique. The merits of the proposed result lie in less conservatism, which are realized by choosing different Lyapunov matrices in the variable delay subintervals and estimating the upper bound of some cross term in LK functional more exactly. At last, two well-known numerical examples are employed to show the effectiveness and less conservatism of the proposed method.     

Robust design approach to the minimization of functional performance variations of products and systems

Frontiers of Mechanical Engineering - Functional performance variations of products and systems are often used to measure the qualities of products and systems considering the changes in the design...