数控机床在车削变速杆中的应用

随着科学技术的发展，数控机床已在生产中得到了广泛的应用。数控加工是采用数字信息对零件加工过程进行定义，并控制机床进行自动运行的一种自动化加工方法。数控车削是数控加工中使用最多的方法之一。     

数控车削加工工艺分析

在数控加工过程中,工艺分析对于机床的加工效率和零件的加工精度都有重要影响,本文以一个数控车削加工范例对数控车削加工工艺进行了详细的分析.     

模具零件数控车削加工工艺分析研究

随着我国社会生产力的大力发展,我国模具零件数控加工工艺得到很大的发展,数控车削加工工艺对模具零件的加工是十分重要的,通过介绍模具零件数控车削加工的工艺内容,在工艺加工内容的基础之上对模具零件数控车削加工的工艺进行研究和探讨。     

数控加工仿真中的优化离散矢量模型

数控加工仿真是利用计算机模拟数控加工的过程。采用离散知音一法可以有较好的实时性和观察性。但在采用离散矢量法时，离散模型的建立对仿真的效果有很大的影响。而对于常用的彩和均匀离散方式建立起来的仿真模型，对仿真精度与仿真速度的要求无法同时得到满足，本文采用了一种基于非均匀离散的优化模型可以有效地解决此点不足，并将详细论述这种仿真模型的建立、数据更新及其显示等内容。     

航空发动机中小零件数控车削的高效加工探讨

在航空发动机中小零件加工中,采用先进可控的数控车削技术,有利于提升零件的加工质量,提高航空发动机的整体性能。使用复杂零件的超精密加工发发,对小零件进行成型加工,使用小工具CCOS技术完成零件的切削和磨削,技术人员应该在数字化工业设计中做好工艺设计层、工艺工控层和数据转化层的辅助性工作,满足发动机零件的加工要求。本文从航空发动机中小零件数控车削加工特点进行讨论,提出几点有利于小零件数控车削加工效率加强的可行性建议。     

Z-Map模型精简技术的研究

在数控编程技术向着智能化发展的情况下,留量模型在数控加工系统中得到了广泛的应用.文章指出了留量模型在数控编程技术中的重要性,分析了Z-Map模型作为加工用几何模型的优缺点,针对Z-Map模型数据量大的不足提出了一种在Z向误差控制下对Z-Map模型进行精简的算法,建立了一种数据压缩的精简留量模型.文章最后探讨了精简留量模型在刀具轨迹的仿真、生成和优化中的应用情况.     

三角Bézier曲面数控加工刀轨生成算法研究

针对目前三角Bézier曲面数控加工刀轨生成效率与精度较低且难以有效解决刀轨干涉等问题,提出了一种基于三角Bézier曲面的数控加工刀轨快速生成算法,该算法依据三角Bézier曲面模型的型面特征规划刀位驱动点,基于三角Bézier曲面的动态索引获取瞬时加工区域,迭代求解瞬时加工区域中各三角Bézier曲面片对应刀位点,...     

数控仿真系统的开发与研究

介绍了数控原理、数控机床、数控仿真技术以及数控仿真系统开发的原理及方法；通过基于OpenGL的数控加工仿真软件系统验证了可行性。此仿真系统的实现，是基于OpenGL，用Visual C＋＋6．0编写的．其中调用了多个OpenGL库函数。     

数控加工仿真系统在设计制造业中的应用

在数控加工技术在设计制造业得到大规模应用的今天，数控加工仿真系统——作为数控加工技术的必要保障，也得到了越来越多的重视。数控加工仿真系统在制造行业的应用范围广泛，小到一个螺钉的制造，大到飞机、导弹的研制都离不开数控加工仿真系统的作用。本文将从分析数控加工仿真系统的概念及特点出发，对其在设计制造行业中的应用进行探讨。     

飞机结构件加工域单元分层识别及构造方法

加工域的自动识别是自动数控加工编程的关键技术之一。为实现飞机结构件自动数控加工程序编制过程中工序件加工域的自动识别,建立了加工域模型,提出了一种实用、可行的域元分层识别方法。首先,根据工序件构建分层面,截切零件和毛坯;其次,依据层交结果构建层域元轮廓,生成层域元;然后,建立规则合并层域元生成域元;最后,通过匹配域元间纵向关系,构建域元树状模型。通过对飞机结构件的测试,证明了该方法的有效性和实用性。     

Multivariate statistical process control for autocorrelated processes

Multivariate statistical process control is often used in chemical and process industries where autocorrelation is most prevalent. We present a realistic model that generates autocorrelation and crosscorrelation and provides a useful approach to characterizing process data. We show how our model relates to the widely-used method of principal component analysis, distinguish between types of assignable causes, and present a useful control statistic based on a principal component decomposition that is not autocorrelated. The control chart for this statistic can be developed by a routine analysis even when the input data is autocorrelated. Furthermore, to characterize our results, we show that any linear combination of the input data that is not autocorrelated is related to our control statistic.     

基于拉普拉斯网格变形的三维植物叶片建模

论文提出一种基于拉普拉斯网格变形的三维植物叶片交互式设计方法。该方法以叶片轮廓及叶片主脉中轴点数据输入并生成网格曲面,通过拉普拉斯网格变形技术对叶片的曲面网格进行交互式编辑。轮廓中轴数据点既可以通过三维数字化获得,也可以根据叶脉形态计算得到。实验证明,该方法具有较好的普适性,变形计算快速,能够达到实时交互设计的需要,所生成的叶片不仅能够很好地保持叶片的面积特征,同时在形态上具有较强的真实感。     

Real‐time Reliability Evaluation for an Individual Product Based on Change‐point Gamma and Wiener Process

Reliability evaluation based on degradation data has received significant attentions in recent years. However, existing works often assume that the degradation evolution over time is governed by a single stochastic process, which may not be realistic if change points exist. Here, for cases of degradation with change points, this paper attempts to capture the degradation process with a multi‐phase degradation model and find the method to evaluate the real‐time reliability of the product being monitored. Once new degradation information becomes available, the evaluation results are adaptively updated through the Bayesian method. In particular, for a two‐stage degradation process of liquid coupling devices (LCDs), a model named as change‐point gamma and Wiener process is developed, after which issues of real‐time reliability evaluation and parameters’ estimation are addressed in detail. Finally, the proposed method is illustrated by a case study of LCDs, and the corresponding results indicate that trustful evaluation results depend on the fitting accuracy in cases of multi‐phase degradation process. Copyright © 2013 John Wiley & Sons, Ltd.     

二阶线性时不变测量系统动态特性的补偿与动态不确定度评估

采用一种新的设计测量系统补偿滤波器的方法,根据校准得到的测量系统频率响应数据直接设计补偿滤波器,避免了系统辨识过程。通过接近实际测量条件的仿真实验表明,该方法能有效地提高测量系统的带宽,减小动态误差。同时,按照GUM推荐的不确定度评定准则,对整个动态测量过程,包括动态补偿以及滤波运算过程的不确定度进行了评估,得到了经过补偿后系统输出的被测量以及对应的动态不确定度曲线。     

On the toughness of particulate filled polymers

An approach for predicting trends in the toughness of particulate filled polymers has been presented. The approach is based on independent knowledge of the constitutive law that describes the non-linear behaviour in the process zone. An idealized law is used to demonstrate expected trends with particulate volume fraction and size. The trends are correlated with experimental data. Some discussion of the non-linear process zone mechanisms, such as debonding and microcracking, is presented as a basis for developing more realistic constitutive laws and hence, providing superior predictions of toughness.     

基于自由变形技术的二维机织物细观模型

为了避免理想化织物模型横截面恒定、纱线间相互渗透的问题,生成具有真实感的二维机织物三维细观模型,提出一种基于自由变形技术的几何变形方法。首先通过理想化的纱线中心线轨迹、横截面建立织物初始几何模型,然后应用自由变形技术对纱线进行变形。在变形过程中,所有纱线横截面在空间位置和参数的约束下进行自由变形,所有横截面变形后的控制网格组成纱线的控制网格,以驱动纱线的整体变形,最终生成具有真实感的织物细观模型。变形过程中纱线间的接触应用基于射线的碰撞检测技术处理。该方法可以扩展并应用于其他织物结构,且可以输出到其他软件中进行模拟计算。      

Modelling and analysis of the sugar cataract development process using stochastic hybrid systems

Modelling and analysis of biochemical systems such as sugar cataract development (SCD) are critical because they can provide new insights into systems, which cannot be easily tested with experiments; however, they are challenging problems due to the highly coupled chemical reactions that are involved. The authors present a stochastic hybrid system (SHS) framework for modelling biochemical systems and demonstrate the approach for the SCD process. A novel feature of the framework is that it allows modelling the effect of drug treatment on the system dynamics. The authors validate the three sugar cataract models by comparing trajectories computed by two simulation algorithms. Further, the authors present a probabilistic verification method for computing the probability of sugar cataract formation for different chemical concentrations using safety and reachability analysis methods for SHSs. The verification method employs dynamic programming based on a discretisation of the state space and therefore suffers from the curse of dimensionality. To analyse the SCD process, a parallel dynamic programming implementation that can handle large, realistic systems was developed. Although scalability is a limiting factor, this work demonstrates that the proposed method is feasible for realistic biochemical systems.     

Probabilistic Fatigue Life Prediction and Structural Reliability Evaluation of Turbine Rotors Integrating an Automated Ultrasonic Inspection System

The paper presents a general method and procedure for fatigue reliability assessment integrating automated ultrasonic non-destructive inspections. The basic structure of an automated ultrasonic inspection system is presented. Fatigue reliability assessment methodology is developed using uncertainty quantification models for detection, sizing, and fatigue model parameters. The probability of detection model is based on a classical log-linear model coupling the actual flaw size with the ultrasonic inspection reported size. Using probabilistic modeling, the distribution of the actual flaw size is derived. Reliability assessment procedure using ultrasonic inspection data is suggested. A steam turbine rotor example with realistic ultrasonic inspection data is presented to demonstrate the overall method. Calculations and interpretations of assessment results based on risk recommendations for industrial applications are given.     

Production system redesign using realistic visualisation

The process of redesigning production systems is usually complex, for which virtual design tools are available. These tools are used to analyse and evaluate planned changes prior to implementation, making it possible to identify and prevent costly design mistakes. Despite this, design mistakes arise during and after the implementation. A source for design mistakes is incorrect or insufficient spatial data of the production systems used in the virtual design tools. The aim of this paper is to show how to reduce the time required for planning and implementing the redesign by supporting the process with realistic visualisation, created from accurate spatial data of the real production systems. Three industrial studies were carried out to evaluate how address realistic visualisation in order to support the redesign process. The result shows terrestrial 3D laser scanning to be suitable for capturing spatial data for realistic visualisation of production systems. The realistic visualisation can be used to virtually analyse design alternatives of the production systems, by, for example, combining the 3D laser scan data with 3D CAD models. The realistic visualisation enabling effective and accurate planning, which gives the opportunity to reduce the time required for planning and implementing redesigned production systems.     

A numerical simulation to relate the shot peening parameters to the induced residual stresses

This paper presents a computational modelling of the shot peening process, in which the finite element method was employed to study the elastic–plastic dynamic process of shots impacting on a metallic target, and the discrete element method was used to study the multiple particles dynamics. The results demonstrated the capability of the method to capture realistic behaviour including the interaction between incoming shots and rebounding shots. Statistical analyses of the shots impact data reveal the relationships between peening process parameters and peening quality, which are useful for identifying the parameters which need to be controlled and regulated in order to produce a more beneficial compressive residual stress distribution within the target.