基于三并联机床螺旋面钻尖刃磨机运动学仿真

介绍了三并联螺旋面钻尖刃磨机床的结构组成,分析并联机床的运动原理.利用ADAMS/View虚拟样机技术建立并联刃磨机床的模型并对机床模型简化处理,设置模型的约束并添加驱动.通过输入运动平台一般条件下运动学参数,更改运动平台不同运动学参数条件,得出机床不同的仿真形态,分析并联机床动平台在不同参数下的并联杆位移速度和加速度关系,为机床系统设计提供理论基础.     

基于ADAMS的并联机床运动学和动力学仿真

以Stewart型并联机床为研究对象，应用ADAMS软件建立了由定平台、动平台、传动杆和工作台等构成的并联机床虚拟样机模型，包括详细的模型简化方法、模型的ADAMS描述及参数化、仿真过程控制，并利用该模型对并联机床的运动学和动力学进行了仿真，实现了在计算机上仿真分析并联机床的运动和动力性能，为并联机床工程设计提供了一套有效的分析方法。     

基于蒙特卡洛法的并联机床误差分析

以3-TPT并联机床为样机,就驱动杆杆长误差以及铰链点间隙误差对其运动平台位置误差的影响建立了误差模型,然后根据蒙特卡洛法对误差模型进行抽样,并用Matlab软件对其进行了仿真分析。从仿真结果可以看出,同时作用所产生的并联机床运动平台的位置综合误差在0.56～0.75mm之间,为连杆杆长误差以及虎克铰累积间隙误差的1/2.3～1/1.7,即小于输入累积误差之和。进而说明3-TPT并联机床的累积误差较小,且误差小于分别作用时的误差之和。     

采用配重法分析3-PRS并联机床静态平衡

配重法分析3-PRS并联机床的静态平衡问题,验证其优缺点。首先设计了平衡机构,动平台通过平行四边形伸缩机构平衡,其它三杆分别通过三个配重滑轮机构进行平衡。分析了并联机床各运动构件的质心,推导出了驱动杆质心和动平台的质心的方程表达式,通过平衡分析和算例得出,可以实现机床在整个工作空间任意位姿下驱动杆均不需要输出关节力克服机床重力。最后利用ADAMS仿真软件对施加配重的并联机床仿真验证,证明了理论分析是正确,配重法不需要对机床进行维护,并可以完全实现并联机床的静平衡。     

虚拟轴并联机床多柔体运动误差分析

主要介绍了在Adams中对虚拟轴并联机床进行正逆解仿真分析的方法,在考虑机构柔性的情况下,结合Malab对一种五自由度虚拟轴并联机床的逆解和正解及额定负载下的运动误差进行分析。先用点驱动定义该机构末端的运动轨迹,仿真后测量得到各主动副的位移时间曲线即为逆解曲线。然后通过后处理模块对曲线进行处理,得到主动幅的驱动样条函数,再把该函数施加在五个主动幅上进行仿真,得到的机器末端位姿曲线即为正解轨迹。采用该方法分别对多刚体虚拟轴并联机床的运动轨迹和多柔体虚拟轴并联机床的运动轨迹进行了分析,通过分析发现该虚拟轴并联机床具有刚度大、精度高等优点。     

一种新型三自由度虚轴坐标测量机机构的误差建模与仿真

设计了一种新型三自由度虚轴坐标测量机机构,给出了其运动学正解模型,依据全微分理论,导出测头位置误差与结构参数误差及3个并联驱动杆长度误差之间的相互关系,从而建立起这种新型并联机构的误差模型;然后利用计算机仿真方法,验证了误差模型的准确性,分析了3个并联驱动杆长度变化以及结构参数误差变化对测头位置误差的影响,为该虚轴坐标测量机机构的加工制造及其误差补偿奠定了理论基础,该并联机构还可用于运动模拟器、并联机床等其它并联运动装备.     

基于虚拟样机技术的3-UPS并联机床仿真研究

以3-UPS并联机床为研究对象，应用虚拟样机技术建立参数化仿真模型，给出了并联机床虚拟样机设计流程和系统结构。利用该样机模型对并联机床进行了运动学和动力学分析，为并联机床结构和数控系统设计提供了主要参数和理论依据。     

并联机床运动仿真与运动学分析的新方法

为了不建立数学模型完成并联机床机构的运动仿真和运动学分析，提出综合利用CAD软件所具有的装配约束和尺寸驱动功能实现运动仿真和运动学分析的方法。给定刀具位置与姿态的驱动尺寸和杆件长度的被驱动尺寸，在装配约束作用下驱动尺寸带动整个机构运动，实现运动仿真，记录杆件长度的被驱动尺寸，得到杆长的值。用Matlab软件拟合杆长数据，得到刀具位姿（驱动尺寸）与每个杆长值（被驱动尺寸）的拟合曲线和拟合方程，求解了杆件的速度和加速度方程。计算机模拟结果表明，并联机床运动仿真与运动学分析方法简捷直观，速度快，求解精度高，可完成其他多自由度并联机构的运动仿真和运动学分析，是并联机构的运动仿真和运动学分析的有效工具。     

基于运动分析平合的并联机床加工运动仿真研究

针对6自由度纯并联机床，提出了以运动分析软件为平台，利用刀位信息驱动机床运动进行数控机床加工运动仿真的技术方案。描述了系统信息流程和算法细节，通过加工仿真试验验证了系统的有效性，为并联机床虚拟产品设计系统的实现和加工技术研究提供了新的仿真方法和技术手段。     

并联机床虚拟概念设计平台的开发

以提高并联机床设计效率和质量为目标,研究了并联机床虚拟概念设计的主要内容,开发出基于ADAMS的并联机床虚拟概念设计平台,建立并联机构型谱库和功能模块组件库,并实现对型谱库和模块组件库的管理.开发并联机床虚拟装配人机交互界面,以帮助设计者完成并联机床的虚拟装配.利用ADAMS的动画技术和仿真分析功能,实现了对样机模型的运动学仿真和分析.     

并联机床数控加工过程仿真方法的开发

针对六自由度数控铣床－并联机床的数控加工,本文提出一种新的加工过程仿真算法。该算法基于观察坐标系,利用扫描线算法在精度范围内表示工件和刀具,从而将复杂的三维布尔运算简化的一维布尔运算。笔者在微机上利用ＶＣ＋＋,根据这种新算法,开发出并联机床数控加工过程仿真系统,实现了并联机床数控加工过程仿真。     

Computer simulation machining a 3D free surface by using a 3-RPRU parallel machine tool

A novel computer aided geometric approach is proposed to machine a 3D free surface by adopting a 3-RPRU parallel machine tool. Based on the geometry constraint and dimension-driving technique, a 3-RPRU parallel simulation mechanism is first created. Next, a 3D free surface and a guiding plane of tool path are constituted. Finally, the 3-RPRU parallel simulation mechanism, the 3D free surface, and the guiding plane of the tool path are combined together, and a novel 3-RPRU simulation parallel machine tool is created for machining a 3D free surface. In the light of two specified tool paths, the extension of the three driving rods and the position of the moving platform are solved and visualized dynamically. Based on the computer simulation results, some analytic formulas are derived to solve the extension of driving rods of the 3-RPRU parallel machine tool in a reverse solving process. From the simulation and analytic results, it is proven that the computer simulation machine tool approach is equivalent to the analytic approach to machine 3D free surfaces. The computer simulation machine tool approach is straightforward without compiling computer programs, and is also advantageous from the viewpoint of accuracy and repeatability. This project is supported by NSFC 50575198.     

并联机床数控加工碰撞干涉检验算法研究

由于并联机床与通用数控机床在结构上差别较大 ,因此在开发与其配套的CAD/CAM系统时 ,考虑到并联机床的结构特点 ,针对哈尔滨工业大学研制的并联机床BJ -30的结构形式 ,提出了并联机床的数控加工碰撞干涉检验算法。该算法较好地解决了刀具过切、少切 ,以及动平台与工件、刀具夹具与工件的碰撞等数控加工中较难解决的问题。仿真结果证明了该算法具有运算速度快、检验效率高等优点     

并联机床加工船用螺旋桨及CAM技术研究

主要研究用并联机床加工整体式船用螺旋桨的技术以及用CAD／CAM系统进行螺旋桨辅助加工的方法。研究了并联机床加工螺旋桨的工艺方案，提出了加工螺旋桨的并串联多轴数控加工系统，分析了螺旋桨数控加工的工艺过程；介绍了在UG／CAM环境下进行螺旋桨加工的刀具轨迹编程和用Vericut加工仿真系统进行加工仿真的方法和过程；并进行加工实验。用于加工螺旋桨的并联机床具有结构简单，造价低和占地面积小等优点，具有广泛的应用价值和发展前景。     

梯形螺纹宏程序的数控仿真加工

介绍了VNUC数控加工仿真软件的仿真加工过程.通过搭建数控车床模型、安装工件、安装刀具、载入程序文件等的仿真环境,尝试用35°硬质合金外圆精车刀加工梯形螺纹,并进行工艺分析与程序设计.利用VNUC软件支持的宏程序功能对梯形螺纹程序仿真并验证,加工的螺纹效果很好.     

Study on symmetrical machining technology

In order to promote machining efficiency of large symmetrical freeform surfaces, a new concept of symmetrical machining is put forward. In addition, problems of collision among cutters or headstocks and machining residue in symmetrical machining are studied in this paper. Through an example of a twin-skeg ship model surface, the design principles of 4-axis symmetrical machine tool are proposed and tool path planning of symmetrical machining is investigated. Based on the above research work, a 4-axis symmetrical machine tool for a ship model surface has been developed. The machining efficiency of the symmetrical machine tool is 85% higher than that of traditional machine tool with a single cutter. Furthermore, the overall cost of the symmetrical machine tool is reduced by saving one set of servo drive system.     

基于变量几何法的两种并联机床法向加工自由曲面仿真

采用CAD变量几何法,用两种新型5自由度3SPS+RRPU和2SPS+RRPRR并联机床对任意3D自由曲面进行法向加工。通过CAD几何约束和尺寸驱动技术,首先建立两种并联机床的模拟机构,再在并联机构动平台上构造任意3D自由曲面和刀具轨迹的引导平面,与并联机构合成,得到模拟并联机床。保持刀具与自由曲面垂直关系,给定加工路径,各驱动杆长和动平台的位置能自动求解和动态显示。结果表明:CAD变量几何法不仅简单直观,而且省去了大量的编程计算。     

Time domain coupled simulation of machine tool dynamics and cutting forces considering the influences of nonlinear friction characteristics and process damping

A higher machining ability is always required for NC machine tools to achieve higher productivity. The self-oscillated vibration called “chatter” is a well-known and significant problem that increases the metal removal rate. The generation process of the chatter vibration can be described as a relationship between cutting force and machine tool dynamics. The characteristics of machine tool feed drives are influenced by the nonlinear friction characteristics of the linear guides. Hence, the nonlinear friction characteristics are expected to affect the machining ability of machines. The influence of the contact between the cutting edge and the workpiece (i.e., process damping) on to the machining ability has also been investigated. This study tries to clarify the influence of the nonlinear friction characteristics of linear guides and ball screws and process damping onto milling operations. A vertical-type machining center is modeled by a multi-body dynamics model with nonlinear friction models. The influence of process damping onto the machine tool dynamics is modeled as stiffness and damping between the tool and the workpiece based on the evaluated frequency response during the milling operation. A time domain-coupled simulation approach between the machine tool behavior and the cutting forces is performed by using the machine tool dynamics model. The simulation results confirm that the nonlinear frictions influence the cutting forces with an effect to suppress the chatter vibration. Furthermore, the influence of process damping can be evaluated by the proposed measurement method and estimated by a time domain simulation.     

Process parameter definition with respect to the behaviour of complex kinematic machine tools

The definition of machining processes with respect to complex kinematic machine tool behaviour involves the control of machine accuracy and kinematic performances. The aim is to propose process settings and tool paths which guarantee the required machining quality while maximizing productivity. This article presents an experimental protocol which enables the determination of machine tool structure behaviours which have an influence on machining quality. In parallel, an experimental analysis of the different kinds of settings which can improve machining quality is carried out. Two kinds of settings appear: the first class of settings improves machining quality or machining time, and the second class has an antagonistic influence on machining quality and machining time. Thus, the definition of the second class of settings arises from an optimisation between first-order defects, second-order defects and machining time. The developed method is illustrated on a parallel kinematic machine tool, the Tripteor X7. Note that this study is a first step towards controlling machine tool behaviour during machining.     

Integrated simulation method for interaction between manufacturing process and machine tool

The interaction between the machining process and the machine tool (IMPMT) plays an important role on high precision components manufacturing. However, most researches are focused on the machining process or the machine tool separately, and the interaction between them has been always overlooked. In this paper, a novel simplified method is proposed to realize the simulation of IMPMT by combining use the finite element method and state space method. In this method, the transfer function of the machine tool is built as a small state space. The small state space is obtained from the complicated finite element model of the whole machine tool. Furthermore, the control system of the machine tool is integrated with the transfer function of the machine tool to generate the cutting trajectory. Then, the tool tip response under the cutting force is used to predict the machined surface. Finally, a case study is carried out for a fly-cutting machining process, the dynamic response analysis of an ultra-precision fly-cutting machine tool and the machined surface verifies the effectiveness of this method. This research proposes a simplified method to study the IMPMT, the relationships between the machining process and the machine tool are established and the surface generation is obtained.