夹具定位方案的稳健性及其优化设计

对影响机床夹具定位误差的各种因素进行了综合分析,提出了定位方案稳健性的基本概念.通过优化设计,可使夹具定位精度对各种干扰因素具有不灵敏性,提高其定位质量.对定位方案稳健设计的准则函数和约束条件进行了探讨,提出了一种优化设计建模方法,并给出了设计实列.     

A new approach for force measurement and workpiece clamping in micro-ultrasonic machining

Micro-ultrasonic machining (micro-USM) is a promising micromachining technique to meet the increasing demands of high accuracy in processing the micro-components of hard and brittle materials. Unlike the well-established conventional USM, micro-USM still lacks in its commercial viability. The major concerns in micro-USM process are the accuracy of the setup and dynamic behavior of the system associated with precise force monitoring and robust workpiece clamping. In this study, a new micro-USM system with regards to measurement and monitoring of static force as well as tooling and workpiece clamping is developed. A force measurement and control system is proposed which is well suited for machining conditions in micro-USM. Furthermore, a reliable and quick setup for the vacuum chuck is introduced, which is capable of consistently transmitting the ultrasonic vibration from horn to the workpiece. Measurement of acoustic characteristics as well as experimental investigations is carried out to validate the functionality of the proposed system.     

Optimization of the number and positions of fixture locators in the peripheral milling of a low-rigidity workpiece

In this paper, a method is proposed to optimize the fixture layout in the peripheral milling of a low-rigidity workpiece. Because the locators on the secondary locating surface directly influence the deformation of the workpiece in peripheral milling, this paper deals with the optimization of the number and positions of the locators on the secondary locating surface. The method proposed in this paper includes two stages. In the first stage, the initial number and positions of the locators are determined by adding the locators at the position with the maximum deformation. In the second stage, the number and positions of the locators are optimized. Using the method proposed in this paper, the number of locators is reduced, while the machining accuracy of the workpiece is retained.     

Modeling and analysis of workpiece stability based on the linear programming method

After being located on a machine bed, a workpiece will be subject to gravity and cutting forces during the machining operation. In order to keep the locating precision as well as the production safety, it is necessary to maintain the workpiece stability. In this paper, a linear programming method is proposed for stability analysis of the workpiece. Based on the linear approximation of the friction cone, a quantitative criterion is established to verify the workpiece stability in association with the rationality of the clamping sequence, magnitude of clamping forces and clamping placement. This criterion allows designers to plan reasonably the clamping sequence, magnitude of clamping forces as well as clamping placement. Compared with existing methods, the main advantage of this approach lies in that the sophisticated computing of contact forces between fixture elements and the workpiece is avoided. In this work, both friction and frictionless cases can be easily taken into account in stability analysis. Mathematical formulations of the method are given and some numerical tests are finally demonstrated to validate the proposed method.     

调头镗孔工件与刀具装夹位置的合理确定

本文以提高同轴度为目的，推导出在调头镗孔时，工件固定于工作台上，工作台固定于床身上（刀具进给时）以及装夹刀具之镗轴伸出（工件进给时）的最佳位置。     

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.     

基于特征参数化设计中的尺寸约束及其表示

参数化设计将是新一代ＣＡＤ系统的主要特征。本文从工程设计实际需要出发,以尺寸约束与设计意图间的相互关系为基础,提出了基于特征参数化设计中的尺寸模型表达方法,给出了基于特征参数化设计的实现方式,并以实例说明了其应用。     

行星轮系的可靠性优化设计

介绍对2K-H（NGW）行星轮系的优化设计方法，给出了其数学模型建立方法和计算程序，根据具体设计条件，利用该计算程序可以得出满足可靠性要求的优化设计方案。     

简单孔节流静压气体轴承优化设计的一种解析解法

静压气体轴承在工程中应用广泛,但其设计工作涉及的计算繁琐,工程中多采用图表法或数值计算法。为简化工程计算过程,也为研究气体轴承中各参数间的关系提供直观的分析依据,从解析角度研究了静压气体轴承的优化设计问题。以简单孔节流圆盘静压气体止推轴承为研究对象,以轴承刚度最大为优化准则,首先利用数值计算求出与供气压比对应的最佳节流压比,再利用最小二乘法拟合得到它们的解析关系式,以此为基础,进而求出最佳气膜厚度、最佳承载力、最大刚度和最佳气体流量的解析解,并与精确数值解进行了比较验证。得到的解析解,使气体轴承的工程设计简便、有效。     

A system for the design and manufacture of feature-based parts through the Internet

The Internet has enabled the development of applications for supporting the design and manufacturing of industrial parts and products. Some actions have been performed by some research groups in different parts of the world aiming at conceiving product modeling systems based on the technology of features to allow information sharing, both for the activities related to product development and for manufacturing. This paper describes the implementation of the WebMachining system () developed in a context of e-Mfg and concurrent engineering, aimed at integrating CAD/CAPP/CAM for the remote manufacturing of feature-based cylindrical parts with symmetrical and asymmetrical features through the Internet, using an approach based on multi-agent systems. The information referring to the features is manipulated through a relational database management system. The graphic user interface (GUI) is implemented in Java and HTML. In this GUI, the user inputs the information on the design features that compose the part. Then these data are sent to the server. Since the part is cylindrical, the user models the part in two dimensions, and it can be visualized as three-dimensional through VRML. A database was implemented that stores the information on the product modeled by features, containing information associated with the form features, material features, tolerance features and technological features. These combined pieces of information allow the mapping of design features into machining features, which is fundamental for process planning. The database information is described in this article through the IDEF1X information model.     

基于Matlab优化设计的齿轮CAD建模

这里结合优化设计技术和CAD技术，提出了一个基于齿轮优化设计与齿轮建模绘图一体化的总体方案，从而建立了基于优化的齿轮CAD系统；在对斜齿圆柱齿轮传动进行了优化设计以后，通过高级语言VC＋＋与Matlab优化和绘图软件AutoCAD之间的接口，将优化设计所得的结果送入参数化绘图部分，自动完成齿轮传动的零件图。     

一种新的优化设计方法--梯度极值法

机械结构分布参数优化设计是机械优化设计中的一类典型问题 ,优化设计的目的是寻找一个优化曲线 ,使得目标函数取得极值。从机械结构分布参数优化设计问题入手 ,通过分析、变换 ,引入极大值原理 ,结合共轭梯度法进行求解 ,从而得到了求解这类问题的一种新方法———梯度极值法。     

轴向柱塞泵平面配流副的优化设计模型研究

轴向柱塞泵平面配流副的优化设计模型研究李小宁毕诸明路建萍（南京理工大学制造工程学院２１００９４）１引言轴向柱塞泵平面配流副是指由泵缸体与配流盘组成的转动摩擦副。在工作时，配流副之间的高压液体对缸体产生必要的反推力和反推力矩，以平衡柱塞对缸体产生的压紧...     

面向并联机器人驱动器故障的容错纠错方法研究

基于机构类型演化提出了一种具有驱动器故障容错功能的1TP+3TPRS型并联机器人的新结构;研究了机器人的机械系统容错重构策略;在位置反解的基础上导出了机器人的重构规划算法;对于退化机器人容错性能指标的研究,定义了容错空间影响因子,可以用来衡量机器人在发生故障后的容错操作能力;基于这个指标,提出容错并联机器人的结构参数优设计方法;通过模拟动平台按预期轨迹运动时某驱动器在不同时刻发生故障的情况,比较了退化机器人的工作状况,结果表明基于容错空间影响因子的结构参数优设计方法对于提高容错性能具有重要的意义。     

The use of the Petri net reduction approach for an optimal deadlock prevention policy for flexible manufacturing systems

In a flexible manufacturing system (FMS) with multiple products, deadlocks can arise due to limited shared resources, such as machines, robots, buffers, fixtures etc. The development of efficient deadlock prevention policies, which can optimise the use of system resources, while preventing deadlocks from occurring, has long been an important issue to be addressed. In [1], an optimal deadlock prevention policy was proposed, based on the use of reachability graph (RG) analysis of the Petri net model (PNM) of a given FMS and the synthesis of a set of new net elements, namely places with initial marking and related arcs, to be added to the PNM, using the theory of regions. The policy proposed in [1] is optimal in the sense that it allows the maximal use of resources in the system according to the production requirements. For very big PNMs, the reachability graph of the PNMs becomes very large and the necessary computations to obtain an optimal deadlock prevention policy become more difficult. In this paper, we propose the use of the Petri net reduction approach to simplify very big PNMs so as to make necessary calculations easily in order to obtain an optimal deadlock prevention policy for FMSs. An example is provided for illustration.     

An algorithm for the determination of optimal design parameters of x̄control charts

One of the main difficulties in the use of an economic design of reliable optimum values for the design parameters compared with a control chart is the computation of the design parameters n (sample size), h (sampling interval) and k (control limit factor). A very simple procedure is described in this research to determine the design parameters of an x̄ control chart in Duncan’s economic model, such that they minimise the expected total costs per time unit. Numerical examples give more accurate and more published results.     

双圆弧齿轮滚刀齿形计算及优化设计

从理论上分析了由目前广泛采用的近似造形方法引起的滚刀齿形精度问题,总结出影响滚刀齿形精度的主要因素。利用从双圆弧齿轮基本齿廓方程出发推导出的双圆弧齿轮滚刀通用齿面方程,求出双圆弧齿轮滚刀前刀面齿形方程。通过比较双圆弧齿轮滚刀的理论齿形和设计齿形,求解出双圆弧齿轮滚刀的齿形误差计算公式,并以滚刀设计截面内的最大齿形误差最小化为目标进行双圆弧齿轮滚刀齿形优化设计,最后利用双圆弧滚刀齿形优化后的相关设计参数完成三维参数化造型。     

某型矿用防爆柴油机的设计研究

在概述防爆柴油机特殊性的基础上,针对某型防爆柴油铲运机用防爆柴油机的具体要求,分析提出了防爆柴油机各系统在设计过程应考虑的因素,解决了防爆柴油机在铲运机上的安装布置问题。通过在该机型上的成功使用,验证了该防爆柴油机设计的可行性。     

Simultaneous optimization of fixture and joint positions for non-rigid sheet metal assembly

This paper presents an optimization methodology for non-rigid sheet metal assembly variation by considering part variation, fixture variation, fixture layout, and joint positions, as well as the assembly spring back. The proposed algorithm integrates the finite element analysis (FEA) with a powerful global optimization algorithm, called the mode-pursuing sampling (MPS) method to simultaneously search for the optimal fixture and joint positions in order to minimize the assembly variation. An example application study is presented to demonstrate the optimization procedure and its effectiveness.