基于实时插补的五轴加工非线性误差控制

五轴联动加工线性插补运动时,因旋转轴的影响,机床控制点的运动将使刀具中心偏离编程轨迹,产生非线性误差.以刀具工作台混合型五轴机床为例,在分析该类型五轴加工中非线性误差形成理论基础上,提出一种基于实时插补的非线性误差控制方法,在基于进给速度规划的轨迹插补之后,对插补中相邻插补点之间的非线性误差进行控制.最后通过仿真分析对该方法进行了验证.     

四元数球面Bézier样条插补算法的研究

为了简化五轴CNC数控系统中的刀具定向运动的编程工作,提出一种基于四元数球面Bézier样条插补算法.该算法根据建立的刀具运动的空间数学模型,实时插补计算出刀具路径点和刀具定向矢量.实验结果表明,该算法不仅保证了刀具平移运动和旋转运动的同步协调性,而且有效的提高了加工精度,满足了五轴高速高精的加工要求.     

一种开放式数控系统刀具运动轨迹验证方法

为了更准确的仿真五轴数控机床各运动轴的运动情况,提出一种开放式数控系统刀具运动轨迹验证方法.本方法从运动控制组件中采集运动控制数据,利用五轴机床机构运动学模型,将运动控制数据转换为工件坐标系下刀具的运动轨迹,并以三维线框方式显示.通过CNC系统与CAD系统STL模型数据的交换,实现了刀具运动轨迹与CAD设计模型的分析比较,并设计了轨迹误差计算模型,可以定量分析仿真的刀具运动轨迹.最后通过实验验证了方法的正确性.     

虚拟制造环境下数控机床的运动学建模与仿真

首先利用Pro/E软件建立三轴数控铣床的虚拟模型,以最简化原则建立运动副的坐标系后,对机床结构进行分析,建立了虚拟环境下任意三轴数控机床的通用运动学模型,实现了任意虚拟三轴数控机床运动的通用求解方法。最后结合ADAMS软件对XH-714型三轴数控铣床的圆周运动进行仿真分析,最终验证了所建虚拟数控机床运动学模型的正确性。     

复杂零件数控自动编程与虚拟加工

复杂零件编程加工时,多采用CAD/CAM软件先对零件进行自动编程,再使用虚拟仿真软件验证程序、进行仿真加工,不仅能够真实地模拟在加工过程中刀具的切削、加工零件、夹具、工作台及机床各轴的运动情况,还可以对加工过程进行修改、优化,最后进行实际加工。本文介绍使用CAXA数控车软件对复杂轴类零件进行自动编程,使用VERICUT软件对     

变结构控制系统的品质控制

本文研究变结构控制系统中动态过程的品质及其改善,提出了趋近律及自由递阶控制的新概念。文中应用趋近律作为综合方法所得到的变结构控制,可以保证非滑动运动具有良好品质。趋近律的应用导致了自由递阶控制,比固定顺序递阶控制更为合理,计算上大大简化。     

基于视觉模型成像的六轴焊接机器人关节运动姿态规划研究

由于传统的六轴焊接机器人关节运动姿态规划方法存在关节运动姿态规划精度低、规划时间长的问题,提出基于视觉模型成像的六轴焊接机器人关节运动姿态规划方法.计算摄像机与机器人坐标关系,并通过图像雅克比矩阵,确定图像特征与机器人关系,在工作空间内把直线的始点与终点轨迹离散化,完成坐标转换,获取每个关节角度值,通过围绕焊接机器人各轴角度值确定欧拉角3个变量,利用欧拉角进行姿态规划,实现六轴焊接机器人关节运动姿态规划.实验结果表明,所提方法的六轴焊接机器人关节运动姿态规划精度较高,规划时间较短.     

UCP710五轴机床中的坐标转换

5轴机床是在3轴机床的基础上增加了两个旋转轴,当旋转轴和平移轴作复合运动时,能使刀具和工件曲面始终保持一个固定的夹角,因此,在加工曲面时5轴机床能加工出很光滑的表面。由于旋转轴运动存在,工件在机床坐标系中的位置随时在发生变化,这使得5轴机床的数控编程比3轴机床复杂的     

虚拟维修拆卸路径规划关键技术研究

如何进行合理的拆卸路径规划是虚拟维修技术必须解决的难题之一。在对虚拟维修中拆卸路径规划基本流程分析的基础上,得出虚拟维修拆卸路径规划的关键技术,并提出了基于vgPicker类的拾取方法、基于鼠标运动与虚拟实体运动关联的拖曳方法和一种快速而精确的碰撞检测方法。相关算法在某型装备虚拟维修训练系统VMTS中得到应用,并对其他复杂装备的拆卸维修训练有指导意义。     

侧铣加工中铣刀形状和运动路径的求解

研究五轴联动数控机床侧铣加工中铣刀的形状确定和运动路径的规划问题.利用旋转曲面铣刀和设计曲面呈相切关系的事实,将一个铣刀的刚体运动描述为一个带约束的优化问题并给出求解方法.该方法以用户交互给出的一个线段作为铣刀轴的初始位置,通过计算铣刀的最优刚体运动生成一个轴线段的运动序列,并再通过对旋转曲面的经线做最小二乘拟合得到一个旋转曲面铣刀.实验结果表明,文中方法得到的刀具的运动生成的加工曲面与设计曲面具有较小的逼近误差,从而提供了一种铣刀运动路径优化算法的初始化方法,对提高已有路径优化算法的效率和结果的质量有重要作用.     

On the effective tool path planning algorithms for sculptured surface manufacture

This paper describes the cutter path planning and cutter interference (gouging) analysis algorithms developed to generate optimal tool path for manufacturing sculptured surfaces on three axes CNC machine tools. Cutter path planning algorithm approximates the parametric curves on three dimensional surfaces by a sequence of straight line segments and generates optimal tool paths by minimizing the number of interpolation points while keeping the path deviations within the specified tolerances. Cutter interference analysis algorithm checks for the self intersection of an offset surface and determines the self-intersection curve. The tool path is then planned over the cutter contact (CC) surface after removing the CC data that lies inside the self-intersection curve. Finally, the effectiveness of these algorithms is demonstrated by implementing them in CAD/CAM system.     

Generation of collision-free 5-axis tool paths using a haptic surface

An intuitive man-machine interface for generating 5-axis tool paths is described in the paper. The system is based on a 5 degree-of-freedom force feedback haptic system, which is used to interface a human with an impenetrable 3D part. In the process of feeling the object, the user ‘teaches’ a milling machine to machine a virtual 3D object. The tool path generation has two phases: recording of access directions at the surface of the object and the post-processing phase. During the recording phase, three functions are carried out simultaneously: first, a fast collision detection algorithm, using hierarchical object representation, to drive the haptic system; second, visual feedback to show the regions that have been accessed by the tool; and third, a system to capture the access directions of the tool as the user touches the object. The post-processing phase involves the use of information generated in the recording phase to generate 5-axis tool paths. First, the access directions at the surface of the part are interpolated; and second, any residual collisions are detected and eliminated. We show the results of the tool path generation for two parts. The system can help an expert user generate, correct and tweak tool paths.     

Virtual machining considering dimensional,geometrical and tool deflection errors in three-axis CNC milling machines

Virtual manufacturing systems can provide useful means for products to be manufactured without the need of physical testing on the shop floor. As a result, the time and cost of part production can be decreased. There are different error sources in machine tools such as tool deflection, geometrical deviations of moving axis and thermal distortions of machine tool structures. Some of these errors can be decreased by controlling the machining process and environmental parameters. However other errors like tool deflection and geometrical errors which have a big portion of the total error, need more attention. This paper presents a virtual machining system in order to enforce dimensional, geometrical and tool deflection errors in three-axis milling operations. The system receives 21 dimensional and geometrical errors of a machine tool and machining codes of a specific part as input. The output of the system is the modified codes which will produce actual machined part in the virtual environment.     

Evolutionary optimization of robotic assembly operation sequencing with collision-free paths

Many problems in the lifecycle of product and production development (PPD) can be formulated as optimization problems. But in most of the real-world cases, they are too complex to be solved by analytical models or classical optimization methods. CAx and virtual manufacturing (VM) tools are on the other hand being employed to create virtual representation of products and processes before any physical realization is conducted. Synergy of these two domains is of interest in this paper where planning a process with the minimum cycle-time for assembling a spot welded sheet-metal product is desired. The methodology suggests an extendible virtual manufacturing-based optimization approach using evolutionary algorithms. Accordingly, a novel toolset with integration of evolutionary optimization and a commercial VM environment is developed. More specifically, the latest feature which takes advantage of the collision avoidant segment path planning functionality of the VM tool and integrates it with the sequence optimizer is described.     

直线伺服6 位置环虚拟轴机床的运动学解耦

使用直线电机驱动虚拟轴机床 ,可满足高速时动态响应和提高精度的要求。如何解决 6位置环虚拟轴机床的强耦合 ,一直是虚拟轴机床伺服控制中的一个难题。为此 ,将局部结构化方法与解耦理论相结合 ,提出一种新的解耦算法 ,从理论上实现了对 6位置环虚拟轴机床的平动和转动之间的解耦     

Holistic methodology using computer simulation for optimisation of machine tools

Virtual machine concepts supporting optimisation of machine tools have been developed in earlier work. The virtual machine concept is a tool that can describe the behaviour of a machine tool while considering the interaction between mechanics of the machines and the control system. Considerable amount of work has been done proving the concept and showing the potential of such a design tool in different contexts. Several studies have shown the potential of using the virtual machine concept, although, no work has been found that is exploring the potential of a full optimisation study.     

On the development of a haptic system for rapid product development

This paper presents a system development that extends haptic modeling to a number of key aspects in product development. Since haptic modeling has been developed based on physical laws, it is anticipated that a natural link between the virtual world and practical applications can be established based on haptic interaction. In the proposed system, a haptic device is used as the central mechanism for reverse engineering, shape modeling, real time mechanical property analysis, machining tool path planning and coordinate measuring machine (CMM) tolerance inspection path planning. With all these features in a single haptic system, it is possible to construct a three dimensional part by either haptic shape modeling or reverse engineering, then performing real-time mechanical property analysis in which the stiffness of a part can be felt and intuitively evaluated by the user, or generating collision free cutter tool path and CMM tolerance inspection path. Due to the force feed back in all of the above activities, the product development process is more intuitive, efficient and user-friendly. A prototype system has been developed to demonstrate the proposed capabilities.     

机床控制流程的一种有限状态机表达方法

面向过程的IEC-1131-3规范已难以满足机床 控制流程表达新的应用需求,为了更好地支持控制器开放式体系结构设计和面向对象系统实 现技术,我们扩展了有限状态机的基本概念,提出了一种机床控制流程表达的分层式有限状 态机(FSM)方法．本文首先对分层式FSM的组织方法、特性、形式定义等进行了详细讨论;为 了进一步阐明这种方法的表达特性,我们介绍了一种分层式FSM表达的机床控制器总体结构 ,并讨论了这种结构下的开放性设计表达和系统实现等相关问题．     

Five-axis pencil-cut planning and virtual prototyping with 5-DOF haptic interface

In this paper, techniques of 5-axis pencil-cut machining planning with a 5-DOF (degree of freedom) output haptic interface are presented. Detailed techniques of haptic rendering and tool interference avoidance are discussed for haptic-aided 5-axis pencil-cut tool path generation. Five-axis tool path planning has attracted great attention in CAD/CAM and NC machining. For efficient machining of complex surfaces, pencil-cut uses relatively smaller tools to remove the remaining material at corners or highly curved regions that are inaccessible with larger tools. As a critical problem for 5-axis pencil-cut tool path planning, the tasks of tool orientation determination and tool collision avoidance are achieved with a developed 5-DOF haptic interface. A Two-phase rendering approach is proposed for haptic rendering and force-torque feedback calculation with haptic interface. A Dexel-based volume modeling method is developed for global tool interference avoidance with surrounding components in a 5-axis machining environment. Hardware and software implementation of the haptic pencil-cut system with practical examples are also presented in this paper. The presented technique can be used for CAD/CAM, 5-axis machining planning and virtual prototyping.     

云环境下基于PLC模拟量优化的机床自动控制系统设计

为解决机床控制过程中存在抖振现象和控制误差过高等问题,在云环境下通过对PLC模拟量的优化,从硬件和软件两个方面优化设计机床自动控制系统;加设可编程逻辑控制器,改装传感器、电机与驱动器,调整系统电路的连接方式,完成机床自动控制硬件系统的优化;根据机床生产任务,规划执行刀具移动轨迹,设定机床加工强度与速度参数;在云环境下自动采集机床模拟量与位姿,根据当前机床运行参数与设定参数之间偏差,利用优化PLC的模拟量并生成机床控制指令,实现机床自动控制功能;通过系统测试得出结论：综合两种实验场景,与传统控制系统相比,优化设计系统在机床执行刀具位置、运行速度和执行应力三个方面的控制误差分别降低约13.8 mm、0.26 mm/s和3.4 N,同时机床抖振现象得到显著抑制。