基于Web的虚拟机床加工仿真研究

随着计算机技术和网络技术的迅猛发展,虚拟制造技术成为当前制造业研究的新热点,虚拟加工过程仿真是虚拟制造中的关键技术.论文对基于网络的数控加工仿真关键技术进行了研究.在分析了VRML与JavaScript交互技术、材料去除算法、碰撞检测算法及NC代码编译等建立仿真平台关键技术的基础上,提出了一种基于Web的虚拟机床加工仿真系统.系统可实现Web环境下机床三维浏览、运动仿真、装配显示等功能,同时内嵌基于OpenGL技术开发的曲面加工仿真功能.使用者只需要通过安装相应插件的浏览器,即可对系统进行访问.相对于其他CAM商业软件,其具有系统文件简单,易于模块化扩展等特点.     

数控机床运动误差检测技术(待续)

从数控机床的误差分类、误差模型建立和误差检测装置等三方面综述了数控机床运动误差检测的研究。根据数控机床运动误差检测的实时性、高效性等特点,提出了“工件即基准”为核心的,基于虚拟基准的数控机床运动误差检测方案,该方案具有高柔度、不需要基准件,可实现在机检测等优点。     

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。     

机床导轨直线度误差计算机可视化评定

利用计算机评定直线度误差,克服了手工作图评定直线度误差的繁琐、粗糙性以及计算法的不可观性.介绍了展示程序评定直线度误差的过程,为制造加工与质量鉴定提供了精确误差值和可视化平台.     

基于双模同步预测的机械臂末端轮廓精确跟踪控制

为减小机械臂末端在进行轨迹跟踪运动时的轮廓误差,提出一种机械臂轮廓误差同步预测控制策略.该策略将操作空间轮廓误差映射到关节空间,从而定义机械臂各关节的同步行为,有效减小了末端轮廓误差,提高了机械臂各关节的运动协调性.为解决常规预测控制器不能保证系统稳定的问题,提出双模同步预测控制方法,通过在预测时域外切换到局部控制率来...     

基于支持向量机的加工误差预测建模方法研究

误差补偿是提高机械加工精度的有效途径,其中误差的建模是关键.在分析现有加工误差预测技术不足的基础上,提出基于支持向量机的加工误差回归建模和预测方法,并对实际应用中的问题进行了分析和总结.通过实例验证及与其它建模方法的对比,表明该方法具有优良的预测性能,为加工误差预测提供了一种新的可行方法.     

砂轮磨损对球头立铣刀制造误差的影响研究

球头立铣刀是加工复杂高精度曲面的重要刀具.在磨削加工球头立铣刀的制造过程中,随着磨削时间的增加,砂轮会出现磨损,球头立铣刀的刃形曲线会随之发生变化.文章以SolidWorks为开发平台,基于球头立铣刀前刀面的磨削加工运动关系,利用Visual Basic语言进行二次开发,开发出球头立铣刀前刀面的磨削仿真加工系统和刀具参数分析系统,分析了砂轮磨损对球头立铣刀刃带宽度和刃形曲线的影响.分析结果可为实际加工过程提供理论指导,有助于制定正确的磨削制造工艺,并为后续制定正确误差补偿策略提供重要指导.     

涉及制造因素的水下自航行平台结构强度性能分析

对水下自航行平台(AUV)制造过程中可能产生的主要制造误差进行了分析,针对水下自航行平台的两种主要制造误差-圆柱度和焊接质量,进行了结构有限元计算和强度性能分析.文章指出:圆柱度误差在一定范围内既可满足性能要求又可降低加工难度和加工成本,但是圆柱度误差过大会降低平台结构强度;焊接质量对平台结构强度的影响很明显,应尽量保证焊接质量以避免平台强度不足引起破坏.     

提高快速成型制件精度方法研究

提高快速成型制件质量是快速成型技术研究的热点.快速成型制件的的误差分为尺寸误差、形状误差和表面粗糙度.在熔融堆积成形制造中,形状误差有翘曲变形、台阶效应等形式.产生误差的原因有原理性误差、材料收缩引起的误差、工艺参数引起的误差及设备误差等.分析了各种快速成型制件误差产生的原因,提出减小误差的方法.     

Stewart单三角平台的机构参数标定

通过分析Stewart单三角平台机构各个运动副的安装误差和制造误差以及这些误差对Jacobian矩阵的影响,利用静力影响系数GF f和Jacobian矩阵之间的对偶关系,提出了基于广义力平衡原理Stewart单三角平台机构的标定方法.并运用该方法通过理论推导直接给出了参数标定的解析式,再结合最小二乘法拟合出实际的静力影响系数GF f ,最终标定出各个铰链点的空间坐标.为提高并联机构平台的定位精度提供了一种强有力的方法.     

Digital manufacture of large-grade hydro turbine's blades

The blade is one of the vital components and the most difficulty in manufacturing of large hydro turbines. In order to cost-effectively and productively manufacture these kinds of blades, a series of innovative digital techniques have been developed. It includes the digital design of hydro turbine blades based on manufacturers’ requirements, computer-aided location and the machined error evaluation with three-dimensional digitized measure, tool path generation strategy for enhancing machining efficiency and controlling deviation in NC machining, tool path generation and NC machining simulation by means of a virtual NC machining environment for blades, and feasible strategy and the systematic scheme for manufacturing of large blades with 5-axis simultaneous CNC machining technology. The developed innovative digital manufacture techniques have been successfully applied in the manufacturing of both the large grade Kaplan and Francis hydraulic turbine blades. It has been shown that the higher efficiency and the better surfaces finish accuracy can be achieved in practical engineering.     

虚拟制造技术在模具设计与制造中的应用

讨论了虚拟制造技术在模具设计与制造中的应用，提出了以Solidworks软件为应用平台，利用VBA编程来实现虚拟设计和虚拟装配，并结合Surfcam软件进行虚拟加工的虚拟制造系统开发模式。     

Feed speed scheduling method for parts with rapidly varied geometric feature based on drive constraint of NC machine tool

As the existence of rapidly varied geometric feature and during the NC manufacturing process of this kind of parts, the actual moving speed of the workbench of the NC machine tool cannot reach the feed speed set in the NC program timely due to the drive constraint of NC machine tool. Furthermore, the machine tool would vibrate violently with the drive constraint when employing the constant machining parameter to process the parts with rapidly varied geometric feature, which seriously restricts the improvement of processing this kind of parts with high quality and high efficiency. In order to manufacture such parts with high quality and high efficiency, a sub-regional processing method with variable machining parameters is proposed. Firstly, the generation mechanism of the machining error is studied, and its mathematical model is built. Then the change rule of the machining error influenced by the curvature and the NC programmed feed speed is found out. Finally, taking the drive constraint and the machining error requirement into account, the relationship between the programmed feed speed and the curvature is established, and the corresponding programmed feed speeds to different curvatures are obtained. Taking the NC machining of the edge line of spiral microstrip antenna, which is an equiangular spiral, for example, the experiment results show that compared with the machining result with constant machining parameter, the maximum machining error of the sub-regional processing method with variable machining parameters decreases by 35.51% and the average value of the machining error decreases by 46.65%. For another example, the clover rose line is machined and the processing quality is also improved. This study proves that the method distributing the programmed feed speeds based on the curvature variation can improve the machining precision and ensure processing efficiency, and provides an effective method to manufacture parts with rapidly varied geometric feature.     

基于VERICUT的异型石材罗马柱数控加工仿真

应用VERICUT及UGNX软件,对新开发的八轴双五联动数控异型石材多功能复合加工中心进行虚拟建模,并使用VERICUT软件对异型石材典型制品——罗马柱进行加工仿真研究。通过仿真检测出由UGNX软件自动生成的程序中存在的过切、干涉等问题,并对加工程序进行修改,改善数控加工工艺。通过此法不仅提高了数控机床加工功能和效率,而且降低了生产成本。     

螺旋锥齿轮数控铣齿加工过程几何仿真研究

利用面相对象技术和CAD系统的三维建模功能及其ObjectARX技术，根据螺旋锥齿轮的加工原理，提出了CNC铣齿机、齿坯和刀具三维模型的构建方法以及基于全局光照明的加工环境光照计算的具体方法。利用齿坯实体模型和刀具实体模型做布尔减运算，来实现模拟工件材料的去除过程；同时，采用全局光照明模型建立了具有真实感的数控加工虚拟现实环境。实际应用表明，该系统不但实现了螺旋锥齿轮的计算机辅助铣齿，提高了加工效率，降低了加工成本；而且还提供了非常真实的仿真效果。所获仿真结果可为齿面接触分析、有限元应力分析、齿轮的数控加工等提供精确的三维几何模型。     

虚拟机床加工系统的组件化设计

虚拟机床加工系统的组件化设计使我们建立了一个多总线的、并行的虚拟系统。这个系统能够完成虚拟加工,实现优化加工工艺,预计和检测加工质量的目标。本文对该系统体系结构的一些基本问题进行了研究。由于运用了组件技术,使系统的开放性、可扩展性可强,结构更另灵活。并使虚拟机床加工系统与其他虚拟系统以及ＣＡＤ／ＣＡＭ系统、制造网络上加工地之间的协作更加默契。同时也为今后工作的开展奠定了良好和基础。     

Virtual High Performance Milling

The goal of future manufacturing is to design, test and manufacture parts in a virtual environment before they are manufactured on the shop floor. This paper presents a generalized process simulation and optimization strategy for 2 1/2 axis milling operations to increase Material Removal Rate (MRR) while avoiding machining errors. The process is optimized at two stages. Optimal spindle speed, radial and axial depth of cut are recommended to process planner by considering the chatter, and spindle's torque/power limits. The cutter-part engagement conditions are extracted from CAD system by geometrically processing the NC program and part geometry. Long tool path segments are broken into smaller segments whenever the geometry varies. The spindle speed and feed fields of the NC program are automatically optimized by constraining maximum torque, power, tool deflection and chip load set by the user. The acceleration and speed limits of the machine tool feed drives are considered to prevent frequent variations of the feed unnecessarily. The optimization is experimentally verified by milling a helicopter gear box cover on a high speed, horizontal machining centre.     

Enhanced virtual machining for sculptured surfaces by integrating machine tool error models into NC machining simulation

Sculptured surface machining is a time-consuming and costly process. It requires simultaneously controlled motion of the machine axes. However, positioning inaccuracies or errors exist in machine tools. The combination of error motions of the machine axes will result in a complicated pattern of part geometry errors. In order to quantitatively predict these part geometry errors, a new application framework ‘enhanced virtual machining’ is developed. It integrates machine tool error models into NC machining simulation. The ideal cutter path in the NC program for surface machining is discretized into sub-paths. For each interpolated cutter location, the machine geometric errors are predicted from the machine tool error model. Both the solid modeling approach and the surface modeling approach are used to translate machine geometric errors into part geometry errors for sculptured surface machining. The solid modeling approach obtains the final part geometry by subtracting the tool swept volume from the stock geometric model. The surface modeling approach approximates the actual cutter contact points by calculating the cutting tool motion and geometry. The simulation results show that the machine tool error model can be effectively integrated into sculptured surface machining to predict part geometry errors before the real cutting begins.