新型并联机床曲面加工的运动控制与后置处理算法

以六自由度6PM2混联数控机床为研究对象,阐述其独特结构及特性,指出混联机床数控加工后置处理中的两个关键问题,即刀位数据转换和运动控制算法,给出了后置处理中刀位数据的转换方法和过程,提出了一种基于并联结构和串联结构的新型并联机床即混联机床的运动控制算法。     

新型并联机床曲面加工的运动控制与后置处理算法

以六自由度6PM2混联数控机床为研究对象,阐述其独特结构及特性,指出混联机床数控加工后置处理中的两个关键问题,即刀位数据转换和运动控制算法.给出了后置处理中刀位数据的转换方法和过程,提出了一种基于并联结构和串联结构的新型并联机床即混联机床的运动控制算法.     

新型5自由度并联机床运动控制算法研究

在分析 5 UPS/PRPU 5自由度并联机床机构的基础上 ,介绍了并联机床运动控制的基本原理 ,确定了具体的运动控制算法 ,将输入控制系统的数控刀位数据转化为驱动轴的控制指令 ,从而实现对机床加工过程中刀具位姿的控制。根据该算法编制的数控软件已成功地应用于实际的并联机床控制 ,取得了较好的效果。     

3-(2SPS)并联机床数控编程后置处理

并联机床在进行运动控制时,必须通过位置反解模型,将刀具位姿及速度信息变换为伺服系统各杆杆长的控制指令,所以传统的数控代码不能直接应用在并联机床上。并联机床后置处理器的功能是根据刀位数据文件和机床特性文件,得到机床数控系统能够接受的程序代码。介绍了一种三平动并联机构-3-(2SPS)并联铣床,基于此机构阐述其后置处理,并研究其后置处理过程的一些关键算法。     

面向并联机床的叶片加工程序后置处理及仿真软件研究

采用专用汽轮机叶片编程软件所生成的叶片刀具轨迹具有良好的工艺性,但其针对的是专用机床,不能直接被其他机床使用.通过对专用机床、并联机床的结构进行分析和对加工程序代码的后置处理,开发了面向并联机床的叶片加工程序后置处理软件,实现了专用机床叶片加工程序代码转换为并联机床加工程序代码.同时为了对转换后的叶片刀位轨迹进行仿真,采用OpenGL和多线程技术开发了叶片加工刀位轨迹仿真软件,实现了叶片加工刀位轨迹的仿真.     

并联机床后置处理算法与系统

以6自由度6-TPS型并联机床为模型,阐述了生成控制数据的一般流程,指出后置处理必须解决的两个关键问题——工件坐标系定位和动平台位姿获取。针对不同位形,提出利用综合误差系数和综合误差度来评价终端运动精度,并据此将工件坐标系定位归结为一类兼顾作业空间和运动精度的有约束非线性规划问题;提出了一种利用5自由度刀位文件获得6自由度动平台位姿的方法;研究了笛卡儿空间的插补算法,并比较了两种不同方法所产生的不同刀具插补轨迹。最后介绍了基于以上算法所开发的后置处理系统的结构。     

七轴并联机床数控加工后置处理技术研究

七轴并联机床是在六轴并联机床的基础上，在工作台上串联一个数控转台，实现七轴联动，从而提高了并联机床的加工能力。为了利用七轴并联机床进行数控加工，必须对刀位文件进行后置处理，生成六根驱动杆的杆长和数控转台的转角等数据来驱动并联机床。本文研究了七轴并联机床数控加工的后置处理技术，提出了后置处理的过程以及相关的算法。     

基于并联机床的Pro/E后置处理系统研究

因为并联机床结构的特殊性 ,通用的刀具轨迹后置处理程序无法生成并联机床的数控指令。本文研究基于并联机床的Pro/E后置处理系统的开发 ,解决并联机床编程困难的问题 ,提出后处理的流程和相关算法。     

3-TPS混联机床的运动控制算法的研究

针对一种新型立卧转换式混联机床的运动控制算法进行了研究。根据不同的控制要求。分别对该机床提出了几种运动控制算法。这些算法从控制对象到机床本体的加工运动之间一系列的转换。正是混联机床控制的基础,为数控系统的控制设计提供了参考依据。     

新型5轴混联加工单元的后置处理算法

5轴混联加工单元因其高刚性、快速响应及灵活调姿等优点,已被视为复杂铝合金结构件高效加工的一种替代方案。后置处理是改善此类装备加工能力的重要环节。以一种新型5轴混联加工单元为研究对象,提出一种可提高其加工件表面质量的后置处理算法。首先,基于B样条曲线构造一种双参数曲线插补算法,进行刀尖和刀轴轨迹的光顺处理,并采用参数同步化保证刀尖点与刀轴点的同步插补。其次,通过推导混联加工单元的速度映射模型,构造驱动轴的速度分配算法以确保刀尖进给速度的稳定性;接着,运用混联加工单元的位置逆解与速度分配策略,将其末端的进给速度、光顺处理后的刀尖插补点及刀轴插补点转换成驱动轴的位置与速度运动控制点集,实现混联加工单元刀具轨迹的后置处理;最后,基于前期开发的实验样机开展一组S形试件的切削实验,验证所提后置处理算法的有效性。     

混联数控机床虚拟加工系统的研究与开发

针对混联机床加工过程中干涉检查、空间刀具半径补偿及编程难等问题,分析了混联机床运动学逆解,提出了一种空间任意面内的刀具半径补偿方法,给出了干涉检查的判断条件。以V is-ual C++为开发环境,应用AutoCAD二次开发工具ObjectARX,建立了由NC代码驱动的混联数控机床加工仿真系统,实现了以真实加工条件为依据的加工过程实时动态模拟,预估加工的过程和结果,为检查NC代码的正确性提供了可靠的依据。     

Post-Processor Development for a Six Degree-of-Freedom Parallel-Link Machine Tool

A coordinate system with multiple non-orthogonal axes, defined for a parallel-link machine tool is very different from that for a conventional serial-type machine. Therefore, a special post-processor that can automatically transfer the cutter location data (CL-data) into machine specific NC commands is essential for real machining applications of a parallel-link machine tool. Parallel-link machine tools have been investigated by many previous workers. However, work on the theory of post-processors for this machine tool is very sparse, and most is focused on the orthogonal serial motion. The potential benefits of the parallel-link machine tools make work necessary and urgent on the transformation of the CL-data from a CAD/CAM system into NC commands for special parallel-link machine tools. A six degrees-of-freedom (DOF) parallel-link machine tool constructed as a 6-3-3 mechanism was selected in this work to investigate the theory of post-processing, and the effects of the cutter shapes and the machine construction on it. The parametric representations of different cutter shapes defined by the DIN standard were adopted in the work, increasing the usefulness of the post-processor theory developed. Specific parameters must be modified in the post-processor for different tools applied for real cutting. The tilt angle and yaw angle of the cutter, relative to the normal direction of the cutting surface, is also included in the theory. Finally, the NC code is generated using LabVIEW software, and simulations were performed to investigate the correctness based on several designed tool paths.     

Postprocessor development of a five-axis machine tool with nutating head and table configuration

The postprocessor is an important interface that transforms cutter location data into machine control data, and in a five-axis machine tool is highly complex because the simultaneous linear and rotary motions occur. Since most works of the five-axis postprocessor method have dealt only with the orthogonal machine tool’s configuration, this study presents a postprocessor scheme for two types of five-axis machine tools, each with a nutating head and a table whose rotational axes are in an inclined plane. The benefit of such a configuration is that it allows switching from vertical to horizontal machining by a single machine. The general analytical equations of NC data are obtained from the forward and inverse kinematics and the homogeneous coordinate transformation matrix. The linearization algorithm for the postprocessor is developed to ensure the machining accuracy. The presented algorithm is implemented using a window-based five-axis postprocessor with nutating axes, and programmed in Borland C++ Builder and OpenGL. A simulation is performed using solid cutting software and a trial-cut experiment was conducted on a five-axis machine tool with a nutating table to elucidate the accuracy of the proposed scheme.     

面向并联机床的后置处理方法

为了解决并联机床的后置处理问题,克服现有方法开发的难度和工作量大的缺点,提出了直接转化传统数控机床数控代码,得到并联机床数控代码的方法。对5-虎克铰-移动副-球铰／移动副-转动副-移动副-虎克铰并联机床和刀具双摆动5轴数控机床进行运动学分析,得出并联机床动平台的两个可变化的姿态角具有与刀具双摆动5轴数控机床中两个摆动转角相同的性质;然后直接利用智能制造后置处理软件进行后置处理得到刀具双摆动5轴数控机床的数控程序;再经过适当的变换,得到并联机床的数控程序。曲面加工的计算机模拟结果表明,该方法正确、有效。     

奥里康制齿轮数控加工运动变换分析

分析了普通奥里康制齿轮机床和六坐标数控切齿机的运动规律，根据传统机床的刀盘和机床调整参数推导出六坐标数控机床加工的运动模型。     

NC Machining of Freeform Pockets with Arbitrary Wall Geometry Using a Grid-Based Navigation Approach

A tool path must be determined in an efficient manner to generate NC (numerical control) code for machining. This is particularly important when machining freeform pockets with arbitrary wall geometry on a three-axis CNC machine. In this paper, a grid-based 3D navigation algorithm for generating NC tool-path data for both linear interpolation and a combination of linear and circular interpolation is presented for three-axis CNC milling of general pockets with sculptured bottom surfaces. The pocket surface is discretised by defining a grid and the navigation algorithm plans the tool motion. The grid size and the cutter diameter are chosen so that a predefined tolerance for surface roughness is satisfied. The grid-based navigation algorithm is simulated graphically and verified experimentally.     

A manufacturing model of helical groove on rotary burr and a universal post processing method

A systematic machining theory and precision method to determine cutter location in a grinding system is presented for rotary burr. First, the helical cutting edge on various kinds of revolving surfaces is built. Then, based on the geometry model of the helical cutting edge, the smooth spiral rake surface with constant normal rake angle and flank surface can been formed during the one-pass grinding process by this method. No interference between the grinding wheel and workpiece happens by the wheel special rotation. The method has the characteristic of detaching the grinding wheel path solution from specified machining conditions. The grinding wheel path is suitable for different NC machine tools through post processing. Meanwhile, a mechanism kinematic model of the NC machine tool is built, and a generalized algorithm for post-processing of multi-axis NC machine tools is presented. This model is applied to arbitrary configuration of NC machine tool, and the motion value for each axis will be generated by the inputting structure and motion parameters of the machine tool. The model, together with the machining method mentioned in this paper, make the calculation and generation of the grinding wheel path simpler and universal. At last, the validity of the method given in the paper is identified by an example of grinding.     

圆环面刀具五坐标数控加工复杂曲面优化刀位算法

本文分析了圆环面刀具的特点 ,提出了一种针对圆环面刀具的五坐标数控宽行加工复杂曲面的刀位计算方法。该算法把曲面离散为点 ,从宏观范围考察瞬时刀位下刀具和型面的接触误差分布 ,并按宏观曲率吻合原则对刀位进行调整优化 ,实现了宽行线接触加工。通过对叶片曲面试算证明了该算法准确。用本算法对UGⅡ软件给出的刀位进行了评估 ,证明其刀位不是优化的     

Research on an algorithm for an NC machining hypoid pinion

Based on the flexibility characteristics of the NC machine tool, which means that various motions can be performed arbitrarily on NC machine tools, a new algorithm for manufacturing a hypoid pinion is proposed. This gets rid of the limitation of traditional mechanical machine tools and their algorithms. When the cutter tilt method is combined with the modification method, a method of manufacturing the pinion with a prescribed-size cutter on an NC machine tool can be realised. This helps to simplify cutter specifications and realise the error compensation of the cutter size. In this paper the algorithm is derived. According to the equations of cutting, the machine settings are calculated.