摆头转台五轴机床倾斜面加工的后处理研究

针对五轴机床加工带倾斜面类零件时使用刀尖跟随功能,不能输出圆弧插补且加工时没有锁定旋转轴导致加工精度差及刚性不高的问题,采用五轴联动数控系统的倾斜面加工功能,提出了基于齐次坐标变换的后处理算法。通过在加工时将工件坐标系围绕原点进行旋转使X/Y平面与加工平面平行,然后利用齐次变换矩阵,分析摆头转台混合型五轴数控机床空间运动坐标系,并对其进行齐次变换运算得到机床运动坐标。最后,使用UG NX8.5/Post Builder编写后处理文件,通过NC代码分析、程序仿真及实际加工验证了后处理方法的正确性。     

双转台五轴机床加工代码的转换与应用

通过分析双转台五轴机床结构与运动方式,研究了该机床结构的加工点位坐标转化规律和数控系统的代码转换规律,并推导出相应的公式。结合自动编程软件进行自由曲面叶轮的加工编程,通过上述推导的公式将编程得到的刀位文件转换为机床能够识别的代码,对生成的代码进行了仿真验证并基于此进行了实际加工,证明了所推导公式的正确性。该研究为用双转台五轴机床加工自由复杂曲面提供了理论基础。     

五轴联动3D刀补矢量后处理算法的研究

研究五轴3D刀补矢量的计算方法,针对A/C轴双转台五轴机床结构模型,分析了五轴数控后置处理过程的相关算法,并针对UG NX6.0五轴刀位数据源文件的数据格式开发了一个专用后处理器,实现了带刀补矢量的五轴NC代码输出转换。为了提高加工效益,提出一种小角度的旋转变换求解算法,实际计算结果表明该算法是正确可行的。     

虚拟仿真技术在多轴机床后处理定制中的应用

对FIDIA五轴立式加工中心后处理的定制过程进行研究,并利用虚拟仿真技术对后处理的正确性进行验证。通过NX软件的后处理构造器定制了适用于FIDIA C1系统的后处理。为了验证后处理的正确性,在NX中建立简化的机床几何模型,将机床各部件以STL格式文件导出至VERICUT软件中,在VERICUT中进行相应的配置,完成虚拟仿真环境的构建;以鼠标模型作为加工对象,在NX加工模块中创建刀具轨迹,通过定制好的后处理将刀轨源文件转换为机床能够识别的NC代码,在虚拟仿真环境中进行模拟加工,验证无误后传输至机床进行零件的实际加工。结果表明:虚拟仿真技术可以有效避免由于后处理定制不当而导致的机床碰撞,确保机床安全、高效地运行。     

五轴数控机床后置处理开发及奇异点规避

机床后处理开发是数控加工技术的关键问题之一,五轴机床运动过程中可能出现的奇异点及其对加工造成的影响在后处理开发过程中极易被忽略。对此,文章基于刚体变换原理,推导了B-C轴式双转台五轴数控机床的运动转换关系,对五轴机床运动可能出现的奇异点现象进行了分析及规避,开发了实验室德玛吉DMU50五轴数控机床专用后置处理文件,经过加工仿真及实验验证,该后置处理对坐标转换计算正确,可以在机床上实际应用,有效的提高了机床的利用效率。     

一体化舱体狭小空间孔的数控加工

某型号一体化加工航天器产品安装孔位于舱体内部,且上部存在特征干涉,常规加工方式无法实现该部位的加工。针对此问题,通过分析直角铣头的结构特点,研究华中数控系统刀尖点补偿算法,实现机床控制器与直角铣头刀尖点的双向补偿;结合龙门五轴机床结构及坐标系变换特点,开展基于NX的后处理开发,完成基于直角铣头坐标系补偿的后处理文件开发,在原后处理不改变的情况下,以事件形式实现直角铣头补偿程序的自动输出,成功解决了超薄舱体内部狭小部位安装孔加工,提高了华中数控系统龙门五轴机床的适用性。     

双摆台五坐标铣削后置处理软件Star-Fpost研究

针对MIRON UCP800双摆台立式五坐标加工中心,研究其五坐标加工的数学模型.推导出刀心和刀轴矢量六坐标转换成AC双摆台式五坐标的算法公式.利用坐标矩阵转换的方法实现直线圆弧插补刀轨源文件到机床代码的后置处理过程.使用面向对象程序,采取逐行读取刀轨文件关键字触发的方式,开发了专用的五坐标铣削后置处理软件Star-Fpost,在VERICUT仿真环境中完成五坐标机床的建模,在UGNX通过三元整体轴径流式叶轮的仿真加工,仿真结果验证了后置处理软件的功能,可以为MIKRON UCP800五坐标机床实际加工提供参考.     

基于NCSIMUL的五轴机床虚拟仿真技术研究

针对五轴加工机床存在程序编制复杂,人工检查困难,加工过程中易碰撞等问题,以Mikron HEM 500 U五轴加工中心机床为例,研究了双摆台五轴加工中心结构,提出了应用NCSIMUL软件构建虚拟机床的方法,搭建了虚拟加工环境,通过叶轮零件仿真加工,完成了APT刀位源文件到NC代码的自动转换,实现了零件五轴联动加工,验证...     

基于UG8.5足球杯座的5轴数控加工

分析了足球杯座的5轴联动数控加工工艺,通过合理设置UG CAM的驱动方法,刀轴控制,投影矢量等参数,运用定轴加工和5轴联动加工的方法生成程序,经后处理生成NC代码。并通过VERICUT仿真软件进行仿真加工,验证程序正确后可以传输到机床进行实际加工,提高了加工效率,保证产品加工质量,对实际加工具有较强的借鉴意义。     

非正交四轴加工的坐标后处理算法

针对在三轴数控机床上配备回转工作台以构成非正交四轴联动的加工方法,研究了其坐标后处理计算方法,推导了相应的坐标变换公式,最后以一特定工件为例,根据坐标变换公式对刀位数据进行计算,并将机床运动坐标值计算结果编制成NC代码用于实际加工,结果表明该算法正确、可靠.     

基于UG8.5五轴联动机床构建后置处理模块的研究

后置处理是CAM技术中自动数控编程不可或缺的。重点研究了基于UG/Post Builder 8.5后置处理构造器构造适合的通用后置处理模块,阐述了构造后置处理模块的方法和基本过程,构造用于双转台五轴加工中心的后置处理模块。以女神维纳斯三维模型为例,运用该后置处理模块进行后置处理自动生成加工程序。实践证明:女神维纳斯实例加工结果完全符合实际加工的要求,该种构建匹配的后置处理模块的方法可以推广运用,具有很强的实用价值。     

Design of a generic five-axis postprocessor based on generalized kinematics model of machine tool

This paper presents a generic five-axis postprocessor system for various five-axis machine tools. The generalized kinematics model of common five-axis machines is constructed by combining two rotational degrees of freedom on the fixture table and two rotational degrees of freedom on the spindle. The complete analytical equations for NC data are obtained through homogeneous coordinate transformation matrix and inverse kinematics. The derived five-axis NC code expression is a general form suitable for all kinds of five-axis machine tools with three orthogonal linear axes and two orthogonal rotational axes. A window-based postprocessor software written by Borland C++ Builder and OpenGL has been developed according to the presented algorithm. The wireframe model of the configured five-axis machine tool can be promptly shown and rotated/zoomed dynamically on the screen to assist the user to input relevant parameters correctly and efficiently. Through the implementation of the developed postprocessor and the verification by the solid cutting simulation software as well as the real machining experiment, the effectiveness of the proposed scheme was confirmed.     

五轴联动数控加工进给率规划方法

针对五轴联动数控加工中恒定机床进给率下加工刀尖点速度波动的问题,提出了同时考虑机床坐标系和工件坐标系下运动学性能约束的进给率规划方法.首先推导了机床坐标系和工件坐标系之间的运动学变换关系,然后综合考虑了机床各轴运动速度和加速度约束条件,以及刀尖点与工件相对运动速度与加速度约束条件,对各程序段中的机床进给速度进行规划.将该方法主要应用于后置处理,仿真结果表明,规划进给率后,加工时间比恒定进给速度下缩短了32.9%,加工速度更为平滑.     

Total differential methods based universal post processing algorithm considering geometric error for multi-axis NC machine tool

Multi-axis numerical control machining for free-form surfaces needs CAD/CAM system for the cutter location and orientation data. Since these data are defined with respect to the coordinate of workpiece, they need converting for machine control commands in machine coordinate system, through a processing procedure called post processing. In this work, a new universal post processing algorithm considering geometric error for multi-axis machine tool with arbitrary configuration. Firstly, ideal kinematic model and real kinematic model of the multi-axis NC machine tool are built respectively. Difference between the two kinematic models is only whether to consider the machine tool's geometric error or not. Secondly, a universal generalized post processing algorithm containing forward and inverse kinematics solution is designed to solve kinematic models of multi-axis machine tool. Specially, the inverse kinematics solution is used for the ideal kinematic model, while the forward kinematics solution is used for the real kinematic model. Then, a total differential algorithm is applied to improve the calculation speed and reduce the difficulty of inverse kinematics solution. Realization principle of the total differential algorithm is to transform the inverse kinematics solution problem into that one of solving linear equations based on spatial relationship of adjacent cutter locations. Thirdly, to reduce the complexity of geometric error calibration experiment, effect weight of geometric error components is determined by the sensitivity analysis based on orthogonal method, and then the real kinematic model considering geometric error is established. Finally, the universal post processing algorithm based on total differential methods is implemented and demonstrated experimentally in a five-axis machine tool. The results show that the maximum error value can be decreased to one-fifth using the proposed method in this paper.     

五轴数控三维曲线空间刀具姿态求取方法

针对中国眼镜厂商提出以三维曲线为驱动的眼镜框加工技术,设计了以五轴数控机床为目标机床的专用型CAM加工软件,提高了生产效率。根据五轴加工特点,计算刀具姿态向量成为实现三维曲线驱动CAM系统中的关键一步。通过两个规则来确定刀具姿态向量,运用参数方程法求取并优化计算过程,以得到刀触点处所需要的刀具姿态。应用该方法在CAM软件中生成每一刀触点的刀具姿态,并生成G代码,在目标机床上验证了该方法的可行性。     

A new compensation method for geometry errors of five-axis machine tools

The present study aims to establish a new compensation method for geometry errors of five-axis machine tools. In the kinematic coordinate translation of five-axis machine tools, the tool orientation is determined by the motion position of machine rotation axes, whereas the tool tip position is determined by both machine linear axes and rotation axes together. Furthermore, as a nonlinear relationship exists between the workpiece coordinates and the machine axes coordinates, errors in the workpiece coordinate system are not directly related to those of the machine axes coordinate system. Consequently, the present study develops a new compensation method, the decouple method, for geometry errors of five-axis machine tools. The method proposed is based on a model that considers the tool orientation error only related to motion of machine rotation axes, and it further calculates the error compensations for rotation axes and linear axes separately, in contrast to the conventional method of calculating them simultaneously, i.e. determines the compensation of machine rotation axes first, and then calculates the compensation associated with the machine linear axes. Finally, the compensation mechanism is applied in the postprocessor of a CAM system and the effectiveness of error compensation is evaluated in real machine cutting using compensated NC code. In comparison with previous methods, the present compensation method has attributes of being simple, straightforward and without any singularity point in the model. The results indicate that the accuracy of positioning was improved by a factor of 8–10. Hence, the new compensation mechanism proposed in this study can effectively compensate geometry errors of five-axis machine tools.     

VMC850F五轴联动机床坐标变换的研究

以某数控机床研究所研发的VMC850F五轴联动机床为例,通过坐标系统间的变换关系,推导出了刀轴矢量及刀位点运动换模型,对该模型方程进行了求解。根据此算法开发了后置处理器,通过在VMC850F机床上加工叶轮样件得到了验证,为五轴后置处理器的开发提供了参考。     

Bézier polygons for the linearization of dual NURBS curve in five-axis sculptured surface machining

Motivated by the excellent performance of three-axis NURBS interpolation, this paper presents a numerically efficient and accuracy controllable five-axis sculptured surface machining method with dual NURBS curve. Unlike the traditional three-axis NURBS interpolation, a dual NURBS format of the five-axis toolpath is developed to accurately and smoothly describe the tool movement in the part coordinate system. Different from the subdivision methods using the Taylor series expansion or inverse function, a piece-wise Bézier curve method is implemented to fast subdivide the NURBS curve within the user-defined tolerance. A generic rotation tool center point management module is also designed to realize the coordinate transformation and adaptive nonlinear error control for major five-axis machine tools. The overall effectiveness of the proposed five-axis NURBS machining scheme is demonstrated by the five-axis machining of an impeller’s flow channel.     

基于Pro/E的特殊五坐标机床的后置处理器的开发

文章分析了带倾斜转台的特殊五坐标数控机床的结构形式和坐标运动关系,给出了其详细的后置处理算法,并基于Pro/E开发出了相应的后置处理器,基于VER ICUT构建了DMU70V五联动加工中心的几何模型,通过实例仿真和实际加工实验对经开发的后置处理器生成的数控程序进行了仿真加工验证和几何干涉检验,结果表明开发的后置处理器是有效可行的。