虚拟数控车削加工系统结构初探

根据实际加工情况提出了一种虚拟NC车削加工系统的设计方法及实现原理。系统在Visual C 平台上进行开发，利用OpenGL技术建立虚拟加工机床数字化模型；用C 语言实现几何仿真指令的建立并完成物理仿真相关的各个数学模型的建立，在虚拟环境下进行数控车削加工的几何仿真及物理仿真，实现产品的虚拟车削制造。     

高真感虚拟车削加工系统中工件模型的建立

提出对虚拟车削加工中工件物理信息处理的问题，使用扫描体方法实现了实时虚拟加工。同时提出了工件的形状误差和表面误差模型以及切屑生成模型。此方法实现了虚拟车削的高真感仿真，克服了以往的代码校验软件中无工件物理信息和工件的成品信息的缺陷，同时增强了软件的沉浸感。     

虚拟加工物理仿真中的误差分析研究

基于虚拟制造的理论与方法,模拟真实加工条件,建立了面向虚拟数控车削加工环境的加工精度分析系统。该系统基于有限元方法,用有限元法计算刀具-工件在切削要素（切削力、夹紧力、切削温度等）作用下的变形,通过求工件-刀具的布尔差集获取切削后的工件轮廓;利用MATLAB优化工具箱,分析工件轮廓,预测零件加工误差。     

基于虚拟制造技术的复杂曲面工件加工质量分析

随着航天、航空等技术的发展,复杂曲面零件的应用日益广泛,复杂曲面工件加工过程受力情况复杂,因此该类工件是公认的制造工艺难题。将虚拟制造技术应用到曲面工件加工中,并以"S"试件为例详细建立了曲面工件的虚拟加工模型,最后通过五轴机床铣削实验验证了虚拟加工模型的实用性与正确性。说明了虚拟加工技术为提高曲面工件加工精度及加工效率提供了有力的技术支撑。     

面向加工质量预测的虚拟加工检测单元的研制

虚拟制造是在制造科学理论,计算机技术和现代信息技术基础上发展起来的数字化制造技术,建立虚拟物理单元是虚拟制造的基础和关键。提出 虚拟加工检测单元的概念,定义了虚拟加工检测单元的体系结构,分析了影响加工质量的主要因素,建立了虚拟加工检测单元的误差融合模型,提出了虚拟加工检测单元的工件描述模型,开发了虚拟加工检测单元的原型系统。     

一种基于工件几何特征优化的能耗模型及应用

制造过程中能耗的影响因素很多,加工工艺、工艺路线、工件加工特性等都会影响制造系统能耗。针对工件加工制造过程能耗优化问题,首先在工件加工特征层面,提出特征能耗单元概念,并建立特征能耗单元模型。然后利用物元法,结合工件几何特征类树,构建了以特征能耗单元为基础的工件几何特征能耗物元模型。从该模型中提取能耗影响因子k,优化工件几何特征,直观地达到控制工件特征来优化加工制造过程能耗的目的,为控制需加工实现的工件几何特征的目标能耗提供理论参考。最后,以轴类工件外圆特征车削加工为例验证分析了该模型的有效性。     

虚拟数控车削加工误差建模技术研究

对虚拟数控车削加工中影响加工误差的因素进行了分析,并建立了加工误差模型。在VisualC++6.0平台上结合OpenGL图形库对该模型进行了分析验证,结果表明该模型可以有效地计算虚拟数控车削加工中的加工误差,为多重复杂因素物理仿真打下了基础。     

虚拟制造中的车削过程仿真系统研究

车削加工是应用最广泛的加工方法之一,对车削加工过程进行仿真具有重要的理论研究与实际应用价值。为此,基于C++ Builder软件进行了虚拟制造中的车削过程仿真系统研究。该系统可对工件进行仿真加工,并将加工过程显示在屏幕上,以发现制造过程中可能出现的问题,在产品实际生产之前就采取预防措施,从而达到产品一次性制造成功。降低了成本,缩短了产品开发周期;还可以对想象中的制造活动进行仿真,而不消耗现实的资源和能量。     

虚拟数控车削加工精度预测研究

加工质量预测是虚拟制造实用化的重要标志之一。基于虚拟数控加工环境研究车削加工直径尺寸形成机理，简化工艺系统尺寸链得出三瞬心法预测工件加工精度的理论模型；在对工艺系统运动误差和切削力变形误差检测与辨识的基础上，给出了可视化交互式的仿真界面，实现对虚拟数控车削加工精度在线预测；通过试验验证了预测模型的有效性。该研究方法可以用于其他切削加工方式的加工精度预测。     

零件工艺信息的提取与加工过程的三维动态仿真

通过分析虚拟制造中数控加工仿真的相关技术,建立相关数学模型,进行了面向虚拟制造的数控加工仿真系统的研究,在VisualC++6.0开发环境下,基于DXF文件中的工艺信息,开发了以车削为主的数控加工程序自动编制系统,并基于OpenGL三维显示机制,编制了数控车削过程的三维动态仿真系统,实现了由AutoCAD二维几何模型自动编制数控加工程序,并实现三维动态仿真的一体化。利用本系统可以实现自动编制数控加工程序,并可直观、实时地检验数控程序的正确性,观察加工过程。     

Workpiece representation for virtual turning

In order to stay competitive with international markets, companies must deliver new products with higher quality in a shorter time with a broader variety of versions at minimum costs. Virtual manufacturing (VM) is quickly becoming an interesting strategy for product development. Primarily aimed at reducing the lead times to market and costs associated with new product development, VM offers a test-bed for the time-consuming and expensive physical experimentation. In this paper, several key issues for developing a virtual turning test-bed by using virtual manufacturing technology are discussed, i.e., representation of a workpiece with the capability of transferring error data used for machining accuracy prediction and reflecting the machining accuracy, representation of the swept volume of a tool for simulating turning process with high efficiency. The construction of surface topography, a basic model for machining accuracy prediction is also highlighted. The representations and relevant algorithms discussed in this paper are implemented in a virtual turning test-bed. A virtual machining and inspection system (VMIS) for ultra-precision diamond turning is presented and experiments are carried out to demonstrate it.     

Machining fixture layout design using ant colony algorithm based continuous optimization method

In any machining fixture, the workpiece elastic deformation caused during machining influences the dimensional and form errors of the workpiece. Placing each locator and clamp in an optimal place can minimize the elastic deformation of the workpiece, which in turn minimizes the dimensional and form errors of the workpiece. Design of fixture configuration (layout) is a procedure to establish the workpiece–fixture contact through optimal positioning of clamping and locating elements. In this paper, an ant colony algorithm (ACA) based discrete and continuous optimization methods are applied for optimizing the machining fixture layout so that the workpiece elastic deformation is minimized. The finite element method (FEM) is used for determining the dynamic response of the workpiece caused due to machining and clamping forces. The dynamic response of the workpiece is simulated for all ACA runs. This paper proves that the ACA-based continuous fixture layout optimization method exhibits the better results than that of ACA-based discrete fixture layout optimization method.     

砂轮约束磨粒喷射加工表面材料去除机理

基于磨粒特征尺寸与砂轮、工件间液膜厚度比值的变化研究了磨粒喷射光整加工的材料去除机理,建立了两体研磨及三体冲蚀单颗磨粒的材料去除模型和材料去除率模型。试验在MB1332A外圆磨床上完成,加工试样为Sa=06μm左右的45钢。加工表面形貌和微观几何参数分别用SEM和MICROMESVRE2表面轮廓仪测量,试验结果和材料去除模型相吻合。试样表面连续的方向一致的沟槽被随机不连续的微坑所代替,随着加工循环的增加,Sa值由06μm下降到02μm左右。此外,光整加工可以获得各向同性网纹交错的表面,表面轮廓的支撑长度率提高,对工件的耐磨性有利。      

Vector model-based workpiece update in multi-axis milling by moving surface of revolution

This paper presents a parametric approach to updating workpiece surfaces in a virtual environment. The workpiece surfaces are represented by a series of discrete vectors, which may be orientated in different directions. The methodology is developed for multi-axis machining in which a tool can be arbitrarily oriented in space. The cutter is modeled as a surface of revolution, which is a canal surface formed by sweeping a sphere with varying radius along a spine curve. To define the tool swept envelope, the cutter surfaces are decomposed into a set of characteristic circles which are generated by a two-parameter family of spheres. Then, the grazing points, at which the discrete vectors can intersect the tool envelope, are obtained by considering the relationships between these circles and feed vector of the cutter. From this, the envelope-vector intersections are transformed into a single-variable function. Examples of this technique are generated for typical milling tools with both linear and circular spine curves. The vector/tool envelope intersection calculations for cutters with linear spine curves can be performed analytically. However, the intersection calculations for cutters having circular spine curves require solving a system of nonlinear equations. For this purpose, a root-finding analysis is developed for guaranteeing the root(s) in the given interval. Finally, to improve the efficiency when updating the workpiece, a vector localization scheme is developed based on the Axis-aligned Bounding Box method.     

并联机床加工精度保障体制

文章对并联机床加工精度的保障系统进行了介绍,该系统涉及分辨率分析、复位位置保证、结构参数标定、工件坐标系建立、刀具长度检测、非线性误差控制、加工零件表面测量以及加工数据基准修正等多个环节,贯穿于机床的设计、制造、控制及加工产品检验等整个过程中.     

面向加工特征的工件制造过程能耗预测方法

在工件的制造过程中,具有多个特征的工件在加工时,其加工特征的能耗属性不同,为了研究在工件不同的加工特征对能耗的影响,创建了面向加工特征的工件制造过程能耗预测模型。首先,将工件看成单个加工特征的集合体,其次对工件特征切削功率的分析,创建有关切削功率的能耗数学模型;然后采用GM(1,1)模型完成工件加工时其切削功率的灰色建模,实现整个工件能耗的预测过程,最后通过对冲床顶支座的加工过程为例,说明了该模型的准确性。     

On-line Estimation of Workpiece Height by Using Neural Networks and Hierarchical Adaptive Control of WEDM

Wire breakage and unstable machining drastically reduce the machining efficiency and accuracy in wire electrical discharge machining (WEDM). When a stair-shaped workpiece is machined, poor electrolyte flow around the steps leads to wire rupture or unstable machining. This paper presents a WEDM adaptive control system that maintains optimal machining and improves the stability of machining at the stair section where workpiece thickness changes. A three-layer back propagation neural network is used to estimate the thickness of a workpiece. The developed adaptive control system is executed in the hierarchical structure of three control loops, using fuzzy control strategy. In the first control loop, the total sparking frequency is controlled within a safe level for wire rupture suppression. In the second control loop, the proportion of abnormal sparks is maintained at a pre-determined level for process control purposes. Based on the estimated thickness of a workpiece, adaptive parameter optimisation is carried out to determine the optimal machining settings and to provide the reference targets for the other two control loops. Experimental results demonstrate that the workpiece height can be estimated by using a feed-forward neural network. The developed adaptive control system results in faster machining and better machining stability than does the commonly used gap voltage control system.     

用触发式测头实现牙掌在线检测

在SSK—U6035五轴加工中心上，利用触发式测头（英国雷尼绍的MP10工件测头）系统和相应的检测自动编程系统实现牙掌在线定位、测量、数据处理、误差校正控制和加工一体化，大大提高了加工中心利用率和工件加工精度，降低了废品率。同时增加了该机床的功能，提高了检测自动化的程度，并且为其他类型的工件检测提供了新的方法。     

弱刚度件加工变形分析与控制对策研究

针对弱刚度件在机械加工中容易产生变形从而影响其加工精度和加工质量的情况,首先分析了引起弱刚度件加工误差以及加工变形的原因,比较了其与大型结构件加工的区别.其次,采用通用有限元软件ANSYS10.0对具有典型结构的特征弱刚度件加工变形进行了数值模拟,从数值方法上预测分析了其变形规律.最后,根据引起弱刚度构件加工变形的原因以及变形规律,对弱刚度件加工工艺方法以及加工变形控制对策进行了探讨.