基于多体系统运动学的龙门铣床加工精度预测模型

五轴联动数控加工运动复杂,影响零件加工精度的误差因素很多,综合考虑多种误差因素,分析了各级工艺链系统的综合误差,提出了基于多体系统运动学理论建立工艺系统综合误差模型;在零件加工之前对零件的加工精度进行预测;通过切削试加工验证模型的可靠性。切削试加工实验证实了基于多体系统运动学的数学模型对零件加工精度预测的准确性和有效性,为今后进一步的研究及误差补偿提供了依据。     

电火花线切割拐角加工精度的实时预测

提出了一种电火花线切割加工拐角加工精度的实时预测方法,并为此建立了实时预测系统.系统根据实时采集的放电能量等加工参数,通过电极丝振动解析及数控轨迹与电极丝位置关系的分析,可得出电极丝形变量与加工误差,从而可将拐角加工形状实时地再现于计算机上,实现了拐角加工精度的实时预测.     

基于开放式系统的曲面加工误差动态补偿控制

将基于传感器信息的智能型开放加工系统应用于曲面的高精度加工,提出了曲面加工误差的动态补偿方法。为预测加工误差的补偿量,建立了刀具弯曲模型,分析了刀具弯曲对加工误差的影响。实验结果表明,本系统可有效地提高加工精度,使加工误差降低1／3－1／4。     

基于多体系统理论的数控机床加工精度几何误差预测模型

针对多轴联动数控机床加工精度误差补偿问题,从分析数控机床误差产生机制和建立精度误差补偿模型的角度,提出基于多体系统理论的数控机床加工精度几何误差预测模型。分析B-A摆头五轴龙门数控机床的拓扑结构关系、低序体阵列、各典型体坐标变换,推导出B-A摆头五轴龙门数控机床的精度几何误差预测函数模型。采用平动轴十二线法误差参数辨识算法,计算出B-A摆头五轴数控机床21项空间几何误差,为精度几何误差预测函数提供有效的误差参数。该精度误差参数建模方法,对不同结构和运动关系的数控机床具有通用性,为后续数控机床误差动态实时补偿提高切削加工精度提供了理论基础。     

MASTERCAM编程软件在涡旋槽加工中的应用

涡旋机构是涡旋压缩机中重要的结构, 它的工作性能和质量主要取决于涡旋槽的加工精度和表面粗糙度,只简单的运用传统的编程方法加工涡旋槽很难保证其加工精度,文章提出一种借助计算机编程软件MasterCAM自动生成涡旋槽加工程序的方法,首先在其软件中绘制图形,生成刀具路径,经过软件中的后置处理生成程序,再利用软件中的模拟仿真功能来校验程序,最终将成品程序应用于生产.实践证明,该方法提高了涡旋槽曲线绘制以及数控加工的精度.把这种方法投入生产加工,可以改善涡旋的机械性能和使用寿命,同时也提高了加工效率.     

活塞模具浇注系统的数控加工方法探讨

随着数控技术和CAD/CAM技术的发展,数控加工拥有了越来越重要的地位。在活塞模具的加工制造过程中,对浇注系统的精度要求越来越高,因此采用数控加工成为提高其精度的必要手段。通常应用CAD/CAM软件首先绘制出浇道的三维实体模型,然后选择机床、毛坯、加工方法、刀具以及加工参数后生成刀具路径,在验证正确后生成应用于生产的数控加工程序。     

数控车床加工精度预测系统研究

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与切削力变形误差检测与辨识的基础上,给出了可视化交互性的仿真界面,实现对数控车床加工精度在线预报;试验验证了模型的有效性。     

曲面数控加工精度的研究

分析了影响曲面数控加工精度的因素，研究并提出了从数控程序设计、工艺系统和控制系统等方面提高曲面加工精度的方法。结果表明：数控加工工艺系统特性和数控系统误差是影响加工精度的重要因素，应尽量购置高精度的机床和数控系统，或采用工艺手段，或设置相应补偿参数，由系统自动补偿功能消除；程序设计的优劣也是影响加工精度的主要因素，应从刀具、加工方法、进退刀与走刀方式的选择和刀具路径规划的验证等方面采取措施，以保证曲面加工精度。     

内螺纹磨床的几何误差建模及灵敏度分析

为提高内螺纹磨床的加工精度，建立了内螺纹磨床的几何误差模型并对其进行全局灵敏度分析。首先，基于多体系统理论和齐次坐标变换的方法，建立了砂轮磨削加工系统和砂轮修整系统的几何误差模型，通过误差传递推导出整机加工精度模型；其次，考虑到几何误差作用的随机性和耦合性，建立基于Sobol的拟蒙特卡洛法的全局灵敏度分析模型，识别出影响磨床加工精度的关键几何误差因素。利用MATLAB编写软件，以SCS-180TB的内螺纹磨床的加工误差模型进行灵敏度计算，并验证模拟次数的收敛性。     

高速走丝线切割加工工艺效果仿真系统

建立了高速走丝线切割加工工艺效果仿真系统,可预测加工工艺效果,具有较高的预测精度,并能实现加工参数的优化选取。通过训练模型的功能,该仿真系统能适用于各种类型的高速走丝线切割机,有助于进一步提高高速走丝线切割机的自动化程度和开发智能化系统。     

国际特种加工研究趋势——第17届国际电加工会议综述

对第17届国际电加工会议论文进行了综述．介绍了近年来国内外特种加工领域的最新研究进展。主要内容包括电火花加工（EDM）、线切割加工（WEDM）、电化学加工（ECM）、超声加工（USM）、微细加工、激光加工（LBM）及相关复合加工工艺的研究成果。     

微细超声加工技术的发展现状与评析

对国内外微细超声加工技术的发展进行了系统的综述，重点介绍了机床结构与工具制备、加工模式和基础研究等几个方面的现状，并对其中的一些关键问题进行了分析。     

CimatronE7.1典型加工方法与技巧

结合多年工作经验,介绍了CimatronE7.1的加工流程及其加工技巧.     

超声加工技术的现状及其发展趋势

结合近年来超声加工技术的发展状况,综述了超声加工在深小孔、难加工材料、超声复合加工和微细超声加工等方面的现状,并描述了超声加工技术的发展前景.     

“一次过加工”技术的发展及应用

介绍了“一次过加工”技术的概念,分析了超高速切削、磨削,电解、电火花、精锻、精铸的“一次过加工”技术特点,对其适用场合、相互关系和应用前景做了较为详细的阐述。     

电火花加工技术及应用实例

详细介绍了电火花加工技术的有关因素,并列举了应用实例。通过对调整不同加工参数所得的结果进行了总结。     

高速切削技术的优势及经济性

本文综述了高速切削技术的概念、特点、经济性及其应用。     

Analytical model to determine the critical feed per edge for ductile-brittle transition in milling process of brittle materials

Brittle materials like glass are considered difficult-to-machine because of their high tendency towards brittle fracture during machining. The technological challenge in machining such brittle materials is to achieve material removal by plastic deformation rather than characteristic brittle fracture. In ductile mode machining, the material is removed predominantly by plastic deformation and any cracks produced due to possible fracture in the cutting zone are prevented from extending into the machined surface. This is achieved by selecting an appropriate cutting tool and suitable machining parameters. In ductile machining by milling process, fracture induced cracks are diverted away from final machined surface by selecting a suitable feed per edge less than a critical threshold value. Hence determination of critical feed per edge is of paramount importance to achieve ductile mode machining by milling process. This paper presents an analytical model based on fracture mechanics principles to predict the critical feed per edge in milling process of glass. The size and orientation of cracks originating from brittle fracture during machining have been quantified by using indentation test results and the critical value of feed per edge has been determined analytically as a function of intrinsic materials properties governing brittle fracture and plastic deformation. Furthermore, an equivalent tool included angle has been suggested for machining operation as against the indenter included angle to correlate the indentation and machining test results with improved degree of accuracy. Experimental results validated the proposed model fairly accurately. It has been established that if the longest cracks oriented in radial direction to the cutting edge trajectory are prevented from reaching the final machined surface by selecting a feed per edge less than or equal to a critical value, a crack-free machined surface can be achieved.     

Laser milling of ceramic components

Conventional methods of producing ceramic components are based on sintering technology which requires expensive tooling making it uneconomic for small batch fabrication. Laser milling provides a new method of producing parts in a wide range of materials, including ceramics, directly from CAD data. This paper considers the technical capabilities of laser milling when applied to the machining of microcomponents from alumina and silicon nitride ceramics. The main parameters affecting the material removal characteristics of laser milling are reviewed. A new technique for machining alumina components is proposed emphasising the importance of correct set-up design in achieving a high level of accuracy. Process parameters influencing part quality are analysed and guidelines for machine set-ups are formulated. The paper concludes with an assessment of the accuracy of the laser milling process.     

Modelling of cutting induced workpiece temperatures for dry milling

A thermal model has been developed that predicts machining induced workpiece temperatures for peripheral milling. The model was developed to determine the magnitude and distribution of workpiece temperatures for dry milling of aerospace aluminium alloys. The analytical model incorporates elements of the physical nature of the metal cutting process with analytical approaches developed for grinding to produce a peripheral milling thermal model that is directly applicable to industry. Test and model results show that cutting induced workpiece heating reduces significantly as cutting speed and feedrates are increased. The research suggests that dry machining of aluminium should be carried out at high cutting speeds and feeds to minimise temperature rise in the workpiece.