虚拟数控铣削几何及物理仿真系统的研究

本文讨论了一套虚拟数控铣削几何及物理仿真系统,提出了仿真系统的总体框架,建立了几何模型和物理仿真模型,分析了铣削加工过程中的影响因素,并建立了各种标准件库,进行了加工参数优化,实现了虚拟数控几何仿真与物理仿真的集成。     

西门子802D数控仿真系统设计

数控仿真技术对于数控程序可靠性检验和切削过程预测有良好的效果。文章对数控仿真系统各项功能进行了研究,选择Delphi7作为开发环境,实现了西门子802D数控仿真系统的交互界面设计,开发西门子802D数控仿真系统的界面及菜单,实现了仿真系统对用户操作的响应。     

数控机床加工仿真技术及应用

该文简要论述了数控机床加工仿真技术及其研究现状，介绍了目前国外成熟的数控机床加工仿真软件VERICUT，并且充分应用这种软件的各项功能进行了具体的机床加工仿真和干涉检查及代码优化。     

数控加工仿真技术研究综述

数控加工仿真技术可以形象、直观地模拟数控加工的全过程,为验证数控加工程序的可靠性及预测切削加工过程提供了强有力的工具。介绍了数控加工仿真的关键技术——几何仿真技术、物理仿真技术和图像可视化技术,并分别对此3个数控加工仿真关键技术的研究成果进行分析评述,最后提出了数控加工仿真技术的发展趋势。     

数控仿真技术的回顾与评述

本文在对当前国内外数控切削加工几何仿真和切削过程力学仿真的两个并行发展的研究领域的研究现状和成果的分析评述的基础上，指出了仿真的发展趋势，并提出一种几何仿真和力学仿真相结合的更精确的试切模型。     

大型雕塑曲面零件数控加工编程的关键技术

多轴联动数控加工编程是大型雕塑曲面零件加工的最重要任务之一.本文介绍五轴联动数控加工大型雕塑曲面编程中涉及到的刀位轨迹计算、切削仿真、机床运动碰撞仿真、后置变换等关键技术.针对这些技术进行研究开发,实现了大型水轮机叶片的五轴联动数控加工,并成为叶片加工的编程工具.     

基于OPENGL数控仿真软件的开发

利用计算机图形技术对已编制的数控程序进行加工过程模拟演示,不但可以检验数控程序的正确性和合理性,而且大大降低了以往采用工艺试切方法所带来的高消耗和高成本.本文对数控仿真建模和数控加工仿真实现技术进行了深入的研究.     

燃气轮机速度调节过程的仿真研究

该文针对燃气轮机半实物仿真系统的特点 ,根据惯性容积思想建立了非迭代的燃气轮机模块化仿真模型 ;对半实物仿真系统中的物理部件速度调节器特性进行了实验研究 ,根据物理部件的特性 ,建立了相应的物理部件仿真模型。在EASY5仿真平台上将燃气轮机各模块和速度调节模块组装 ,对影响燃气轮机速度调节过程的各个因素进行了仿真分析 ,仿真结果和实际过程有较好的一致性 ,从而为物理部件与模型模块的连接提供参考和依据     

基于虚拟制造的三维数控仿真系统开发

本文评述了虚拟制造技术和三维数控仿真的含义和发展,结合虚拟制造技术对数控仿真系统进行了研究,提出了三维可视化虚拟加工环境的系统结构,通过对设计过程中相关技术要点的探讨,运用OpenGL、VB和VC 等软件,开发出基于虚拟制造的三维数控仿真系统。     

数控加工三维仿真系统

本文采用Windows98作为开发平台，选择OpenGL作为工具，开发了数控车、铣、钻加工三维仿真系统，系统由数控程序编辑，数控程序检查与解释，仿真计算及仿真显示等模块组成，其特点是基于数控代码的反向仿真，更接近实际车削、铣削、钻削的加工过程。     

Off-line feed rate scheduling using virtual CNC based on an evaluation of cutting performance

This paper presents an advanced technology to automatically determine optimum feed rates for 2 axis CNC machining, without requiring the expertise of a machinist or the information contained in a machining data handbook. Present CAM technology does not consider important physical properties such as cutting forces and machined surface errors. However, the virtual machining system developed in this study can simulate real machining for a given set of NC codes. An analytical model for off-line feed rate scheduling is formulated to improve productivity and machining accuracy. Using this model, it is possible to regulate the cutting force, which drastically improves the overall form accuracy of the machined surface.     

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。     

A knowledge base model for complex forging die machining

Recent evolutions on forging process induce more complex shape on forging die. These evolutions, combined with High Speed Machining (HSM) process of forging die lead to important increase in time for machining preparation. In this context, an original approach for generating machining process based on machining knowledge is proposed in this paper. The core of this approach is to decompose a CAD model of complex forging die in geometrical features. Technological data and topological relations are aggregated to a geometrical feature in order to create machining features. Technological data, such as material, surface roughness and form tolerance are defined during forging process and dies design. These data are used to choose cutting tools and machining strategies. Topological relations define relative positions between the surfaces of the die CAD model. After machining features identification cutting tools and machining strategies currently used in HSM of forging die, are associated to them in order to generate machining sequences. A machining process model is proposed to formalize the links between information imbedded in the machining features and the parameters of cutting tools and machining strategies. At last machining sequences are grouped and ordered to generate the complete die machining process. In this paper the identification of geometrical features is detailed. Geometrical features identification is based on machining knowledge formalization which is translated in the generation of maps from STL models. A map based on the contact area between cutting tools and die shape gives basic geometrical features which are connected or not according to the continuity maps. The proposed approach is illustrated by an application on an industrial study case which was accomplished as part of collaboration.     

加工过程的模糊自适应PID控制

经典的加工过程模型随切削深度、主轴转速、加工材料、刀具形状和磨损程度不同而不同,因而具有时变性。实际加工过程要比理论上推导出的模型复杂得多,是一种具有非线性、时变性和影响因素不确定的复杂系统,甚至难以用合适的数学模型来表示。结合PID和模糊控制两者的优点,建立一种加工过程的模糊自适应PID的控制方法。对模糊自适应PID控制算法进行了理论分析,基于Matlab建立了铣削加工过程的仿真模型。仿真结果表明,运用模糊自适应PID控制方法,系统的调节时间缩短,响应速度加快,抗干扰能力和适应参数变化的能力要优于增益自适应的PID控制。     

A semi-analytical approach to un-deformed chip boundary theory and cutting force prediction in face-hobbing of bevel gears

Rule-of-thumb based design for cutting tools and machining settings in face-hobbing of bevel gears result in cutting tool failures and quality issues. Lack of a virtual machining environment, to efficiently obtain the instantaneous un-deformed chip geometry and predict cutting forces in face-hobbing, causes undesirable production costs in industries. In the present paper, semi-analytical representation of the projection of the un-deformed chip on the rake face of the cutting blades is presented. The proposed approach is drastically fast and more accurate in comparison with numerical methods and can be implemented in a virtual gear machining environment. The cutting system intricate geometry, multi-axis machine tool kinematic chains and the variant cutting velocity along the cutting edge are taken into consideration to obtain the chip geometry efficiently. Then, cutting forces are predicted during face-hobbing by implementing oblique cutting theory using the derived chip geometry and converting face-hobbing into oblique cutting. The proposed methods are applied on two case studies of face-hobbing of bevel gears, and the chip geometry is derived and the cutting forces are predicted.     

人工神经网络预测刀具磨损和切削力

刀具磨损和切削力预测与控制是切削加工过程中需要考虑的重要问题.本文介绍了利用人工神经网络模型预测刀具磨损和切削力的步骤并且针对产生误差的因素进行分析.首先将切削速度、切削深度、切削时间、主轴转速和不同频带的能量值通过归一化法处理,作为输入特征值,对改进的神经网络模型进行训练.然后利用训练完成的神经网络模型预测刀具磨损和切削力.结果表明:神经网络模型能够综合考虑加工过程中更多的影响因素,与经验公式结果对比,具有更高的预测精度.研究结果表明神经网络模型预测刀具磨损和切削力具有可行性和准确性,为刀具结构的优化及加工参数的选择提供了依据.     

三维工序模型切削载荷动态变化的工艺优化策略

综合零件的加工特征及约束条件并引入布尔差运算,可以分解出零件典型面组并 生成对应的工艺路线谱系,达到零件加工工艺快速优化设计的目的。通过分析三维工序模型典 型面组加工时的动态特性,采用B 样条曲线插值参数化的方法构建刀具-工件接触区域动态边界 的统一数学模型,预测切削载荷动态变化状况,并进行切削参数优化达到有效控制切削载荷的 目的。最后以某零件的车削加工为例进行分析,验证该工艺优化策略的可行性。     

Simulation of cutting forces in ball-end milling

The paper presents a simulation system (SCP) that determines the cutting forces in the ball-end milling process. The system is based on numerical methods, computer programme, theoretical knowledge of technological processes, machining and tests performed. The system for simulation of the cutting process combines the technological data base, the analytical and experimental model and the data base SCP. The experimental model contains a collection of variables of the cutting process by means of sensors and transformation of those data into numerical values, which are a starting point for data calculation of characteristic coefficients of materials. The analytical model is used to estimate the tangential, radial and axial cutting forces, along with a material data base obtained from cutting experiments. Ball-end milling test has been conducted to verify simulation results. The simulation results, are the basis for the development of the tool-designing model and for the model of optimization of the machining process cutting parameters.     

Process planning for Floor machining of 2½D pockets based on a morphed spiral tool path pattern

This work proposes a process planning for machining of a Floor which is the most prominent elemental machining feature in a 2½D pocket. Traditionally, the process planning of 2½D pocket machining is posed as stand-alone problem involving either tool selection, tool path generation or machining parameter selection, resulting in sub-optimal plans. For this reason, the tool path generation and feed selection is proposed to be integrated with an objective of minimizing machining time under realistic cutting force constraints for given pocket geometry and cutting tool. A morphed spiral tool path consisting of G¹ continuous biarc and arc spline is proposed as a possible tool path generation strategy with the capability of handling islands in pocket geometry. Proposed tool path enables a constant feed rate and consistent cutting force during machining in typical commercial CNC machine tool. The constant feed selection is based on the tool path and cutting tool geometries as well as dynamic characteristics of mechanical structure of the machine tool to ensure optimal machining performance. The proposed tool path strategy is compared with those generated by commercial CAM software. The calculated tool path length and measured dry machining time show considerable advantage of the proposed tool path. For optimal machining parameter selection, the feed per tooth is iteratively optimized with a pre-calibrated cutting force model, under a cutting force constraint to avoid tool rupture. The optimization result shows around 32% and 40% potential improvement in productivity with one and two feed rate strategies respectively.     

Process planning for Floor machining of 2½D pockets based on a morphed spiral tool path pattern

This work proposes a process planning for machining of a Floor which is the most prominent elemental machining feature in a 2½D pocket. Traditionally, the process planning of 2½D pocket machining is posed as stand-alone problem involving either tool selection, tool path generation or machining parameter selection, resulting in sub-optimal plans. For this reason, the tool path generation and feed selection is proposed to be integrated with an objective of minimizing machining time under realistic cutting force constraints for given pocket geometry and cutting tool. A morphed spiral tool path consisting of G¹ continuous biarc and arc spline is proposed as a possible tool path generation strategy with the capability of handling islands in pocket geometry. Proposed tool path enables a constant feed rate and consistent cutting force during machining in typical commercial CNC machine tool. The constant feed selection is based on the tool path and cutting tool geometries as well as dynamic characteristics of mechanical structure of the machine tool to ensure optimal machining performance. The proposed tool path strategy is compared with those generated by commercial CAM software. The calculated tool path length and measured dry machining time show considerable advantage of the proposed tool path. For optimal machining parameter selection, the feed per tooth is iteratively optimized with a pre-calibrated cutting force model, under a cutting force constraint to avoid tool rupture. The optimization result shows around 32% and 40% potential improvement in productivity with one and two feed rate strategies respectively.