并行微处理系统及其在实时控制中的应用

本文介绍了并行处理中广泛应用的Transputer系统及其对工业实时控制的适用性，并论述了实时控制的并行处理方法。     

Biological cardio-micro-pumps for microbioreactors and analytical micro-systems

Bio-hybrid microsystems actuated by living cells, as micro-bio-actuators and micro-bio-pumps have been developed recently. In these devices biological cells may be powered without external energy sources and the movement or the contraction of muscle cells trigger off the flow of fluid (i.e. culture medium or blood) through microchannels in micro-multi-bioreactor systems. Isolated and in vitro cultured cardiomyocytes (cardiac cells) are the most promising bio-material, which can be used to design a micro-bio-pump/actuator. These spontaneously contracting cells are autonomously powered with glucose as an energy source without any external power supply or stimulus, unlike conventional micro-actuators/micro-pumps. Cardio-micro-bio-pumps/actuators are using collective, synchronous contracting forces of cardiac cells or cardiac cell sheets to drive the flow of fluid. The feasibility of building such actuators was demonstrated in a few examples of bio-hybrid microsystems actuated by single or sheeted cardiomyocytes.     

Sensor guided handling and assembly of active micro-systems

Positioning accuracies in the range of a few micrometers and below are necessary for the assembly of active micro-systems. In order to reach these accuracies, an assembly system for sensor guided micro-assembly is developed in the Collaborative Research Centre 516 “Design and manufacturing of active micro-systems”. The combination of a parallel robot with an integrated 3D vision sensor and a micro-gripper enables to reach relative positioning accuracies below 1 μm.     

数控加工中加工误差预测模型的研究

提出了一个在球头端铣加工中预测复杂曲面加工误差的理论模型.在理论模型的基础上,计算出了曲面各个部分的由刀具变形引起的加工误差.对影响加工误差的诸如切削模式、铣削位置角、曲面几何形状等各种切削状况进行了研究.最后,使用加工中心,在各种加工状况下.通过一系列实验对理论模型进行了验证.并利用计算机图形学工具对二者进行了建模仿真,结果显示理论值与实验值非常吻合.恰好证明了趣论模型在预测表面加工误差方面的适应性非常好.     

虚拟加工中心加工过程算法研究

在虚拟加工环境的建造过程中,关键技术是三维实体的数据结构和加工仿真的逐步成型算法。该文重点研究了毛坯的数据结构特点,四边形离散化方法和毛坯文件的存储格式等,并且分析了三坐标加工中心的加工特点,同时还给出了虚拟加工过程中毛坯被加工成工件的逐步成型算法。该算法在虚拟加工环境中得到了成功应用,文中给出了该算法在三坐标加工中心的验证实例。     

机械加工的误差分析

任何机械加工中都有加工尺寸的概念,无论是加工大型机械上使用的尺寸为?10的螺栓,还是加工手机上使用的尺寸为?0.5的螺钉,它们都具有一定的基准尺寸和公差,且加工后的尺寸会影响到该工件的使用。无论加工误差是0.1 mm,还是0.0001 mm,都可能无法达到工件的加工要求,进而生产出不合格的产品。因此,分析机械加工误差产生的原因,并从根源上解决问题,对提高产品加工的良品率有很大帮助。     

数控加工G代码程序三维加工仿真软件开发

笔者利用Qt平台与OpenGL库开发了一款针对数控加工G代码程序的三维加工仿真软件。该软件能够根据加载的G代码程序提取加工图像点位信息并绘制加工图像并且可以模拟刀具的加工过程,同时可以检测G代码程序的错误并给出错误信息,方便用户提前验证G代码的可行性。通过使用该软件,技术人员无须试加工就可以验证G代码的加工效果,从而能减少资源浪费与缩短开发周期。     

混合加工特征识别方法

介绍一种集成了自动特征识别和用户交互特征定义的混合特征识别方法，该方法采用基于广义痕迹的特征识别建立零件的加工特征模型，通过交互特征定义对已建立的加工特征模型进行局部修改和再解释，在交互特征定义中，用户只需通过选取要修改的特征面定义自己的特征，剩余的面则调用自动特征识别算法处理，特征参数由系统提供的统一算法计算，从而减少了交互的工作量，这种混合特征识别方法有助于提高加工特征识别系统的实用性和健壮性。     

Machining of aerospace titanium alloys

The performance of PCBN (AMBORITE*) and PCD (SYNDITE) has been compared with that of coated tungsten carbide tool currently being used to machine titanium aerospace alloy. Tests confirm that SYNDITE gives a better surface finish, longer tool life and more manageable swarf than other tools. In addition, the “quick-stop” technique establishes that, for all three cutting tools, a layer is formed between the rake face and the underside of the emerging chip which has a fundamental effect on cutting and wear mechanisms.     

Evolutionary Optimization of Machining Processes

Optimization of machining processes plays a key role in meeting the demands for high precision and productivity. The primary challenge for machining process optimization often stems from the fact that the procedure is typically highly constrained and highly non-linear, involving mixed-integer-discrete-continuous design variables. Additionally, machining process models are likely discontinuous, non-explicit, or not analytically differentiable with the design variables. Traditional non-linear optimization techniques are mostly gradient-based, posing many limitations upon application to today’s complex machining models. Genetic Algorithms (GAs) has distinguished itself as a method with the potential for solving highly non-linear, ill-behaved complex machining optimization problems. Unlike traditional optimization techniques, GAs start with a population of different designs and use direct search methods stochastically and deterministically toward optimal and feasible direction. However, GAs still has its own drawbacks when it is applied to machining process optimization, including the lack of efficiency due to its binary representation scheme for continuous design variables, a lack of local fine-tuning capabilities, a lack of a self-adaptation mechanism, and a lack of an effective constraint handling method. A novel and systematic evolutionary algorithm based on GAs is presented in this paper in the areas of problem representation; selection scheme; genetic operators for integer, discrete, and continuous variables; constraint handling method; and population initialization to overcome the underlying drawbacks. The proposed scheme has been applied to two machining problems to demonstrate its superior performance.     

提高机器人扫描加工系统加工精度的方法

将机器人三维扫描系统应用到工业加工中,建立了机器人在线测量加工系统.利用已知半径的标准球体作为参照工具,提出一种基于几何约束的非线性优化方法.在线精确地标定了便携式三维扫描系统和机器人的位姿关系,提高了测量精度.同时,提出一种使用虚拟刀具工具中心点和预补偿机器人系统误差的方法,提高了机器人的加工精度.对吉他的边缘进行扫描和加工的实验结果表明:该系统具有稳定、高精度、易于自动化等优点.     

Towards High-Fidelity Machining Simulation

The main purpose of any machining simulation system is to reveal or mimic the real machining process as accurately as possible. Current simulation systems often use G-code or CL data as input that has inherent drawbacks such as vendor-specific nature, incomplete data, irreversible data conversions and lack of accuracy. These limitations hinder the development of a truthful simulation system. Hence, there is a need for higher-level input data that can assist with accurate simulation for machining processes. In addition, there is also a need to take into account of true behaviour and real-time data of a machine tool. The paper presents a High-Fidelity Machining Simulation solution for more accurate results. STEP-NC is used as the input data as it provides a more complete data model for machining simulations. The status-quo of the machine tool is captured by means of sensors to provide true data values for machining simulation purposes. The outcome of the research provides a smart and better informed simulation environment. The paper reviewed some of the current simulation approaches, highlighted the current simulation problems, discussed input data sources for smart machining simulation and introduced the high-fidelity simulation system architecture.     

加工面点云数据深度学习的加工特征自动识别

加工特征识别是实现CAD/CAPP/CAM系统集成的关键技术.针对传统基于符号推理加工特征识别模式存在鲁棒性问题,提出一种基于加工面点云数据深度学习的加工特征自动识别方法;基于PointNet点云识别框架,构建了一个面向加工面点云数据的加工特征自动识别卷积神经网络;通过收集CAD模型中的加工特征面集和采样点云,构建了适...     

虚拟数控加工系统的构建

讨论实体建模技术和AutoCAD的三维实体建模方法,给出数控加工仿真环境建模方法,包括毛坯、刀具、夹具和机床工作台构建与管理,构建基于实体的数控加工可视化仿真环境.     

数控仿真的实时真实感图形显示

数控仿真是 CAD/ CAM集成系统中一个重要的组成部分 .文中提出的方法 ,从动画显示方式、数据结构和消隐算法三个方面进行了改进 ,大大加快了仿真过程中真实感图形显示的速度 .在微机上实现了实时、动态地显示良好的真实感图形 .     

一种数控铣床的仿真算法

介绍一种在PC机上实现的三轴数控铣床仿真算法，该算法用矩阵网格表示被加工工件的形状，给出在三种常用铣刀下节点深度的计算公式，并 可以在仿真过程中随时放大、缩小、旋转、平移工件。采用该方法已开发出仿真软件。     

纳米级定位应用于工业加工

曾几何时,万分之几英寸就被认为是高精度了,而如今,人们对精度的要求已经达到了亚微米量级。     

加工中心在线检测仿真技术

该文对加工中心在线检测仿真技术进行了研究。详细阐述了虚拟检测环境的建立、检测信息的提取以及虚拟侧头的驱动等问题,并采用面向对象的程序设计思想进行了系统结构设计。该仿真系统采用解释的编译方式,逐行对检测宏程序进行扫描,驱动虚拟侧头进行检测仿真,实现了对检测过程的图形化模拟,可有效地避免检测宏程序的编制错误,提高编程的质量与效率。     

虚拟切削加工系统的设计与实现

虚拟制造是近年出现的一种先进制造技术,虚拟切削加工在虚拟制造中占有重要地位。为了提供虚拟的加工环境和验证工艺设计的正确性,对切削加工过程的计算机仿真方法进行了研究,以OSG作为图形支持系统,用VC++开发了切削加工仿真系统。该系统实现了对毛坯切割的仿真,可对刀具运动切割情况进行实时监控,较好的再现了加工中毛坯的成型过程。