复杂曲面零件在线检测与误差补偿方法

复杂曲面零件的高精度加工与精密检测一直是数字化制造领域的研究热点。为提高复杂曲面零件的加工精度、检测精度,提出一种集数控机床在线检测、加工误差分解与补偿加工为一体的集成化方法。介绍集成化在线检测方法及补偿系统的基本原理,分析数控加工后曲面零件测点数据的误差组成,提出一种基于空间统计分析的加工误差分解方法,在建立基于B样条曲面的确定性曲面回归模型的基础上,对回归模型残差进行空间独立性分析,分解出系统误差和随机误差,进而通过数控代码的修改,实现零件加工过程的系统误差补偿。列举一个曲面零件的加工与检测实例,进行方法有效性验证。通过加工工件的在线检测、误差分解、代码修改及补偿加工等环节,实例零件的加工精度有了大幅提高,而该系统的检测精度也通过与三坐标测量机(Coordinate measuring machine, CMM)检验结果的对比,得到了有效验证。     

精密复杂零件数控加工在线检测与误差补偿技术研究

针对精密复杂零件数控加工离线检测误差大、效率低,在线检测尺寸、形状受限制等问题,建立了基于B样条曲面的确定性曲面回归模型,通过对回归模型残差空间独立性分析,将复杂零件的数控加工误差分解为系统误差和随机误差,通过修改数控代码,实现了精密复杂零件数控加工在线检测及误差补偿。为验证有效性,进行了大量试验,将试验结果与CMM检测结果对比,结果显示提出的在线检测及误差补偿方法行之有效,实现了精密复杂零件数控加工"加工-测量-补偿加工"的闭环制造。     

精密复杂零件数控加工在线检测误差补偿研究

精密复杂零件数控加工产生误差的影响因素较多,难以精确找出各影响因素与加工误差之间的对应关系。从精密复杂零件数控加工精度检测数据出发,建立了基于B样条的精密复杂零件回归模型。通过对回归模型残差空间独立性进行分析,将加工误差分解为系统误差与随机误差。根据分解出的系统误差大小,修改数控代码,进行补偿加工,有效提高了精密复杂零件的数控加工精度。将试验结果与三坐标测量机检测结果进行对比,结果显示在线检测误差补偿方法行之有效。     

复杂曲面零件加工精度的原位检测误差补偿方法

为提高复杂曲面零件的数控机床原位检测精度,分析影响接触式检测系统精度的各项因素及其误差补偿方法。对检测系统的主要误差来源如机床几何误差、测头预行程误差和测头半径误差进行分析研究。在对数控机床的几何误差进行分析和建模的基础上,采用激光干涉仪进行三轴数控机床的单项误差测量和补偿;针对测头检测过程中存在的预行程误差,提出基于径向基函数(Radial basis function, RBF)的预行程误差预测方法,获得测头预行程误差分布图,并对检测系统进行实时预行程误差的补偿;提出改进的三角网格模型顶点法矢计算方法,有效进行三维测头的半径补偿。通过实例零件的加工精度原位检测试验及其与三坐标测量机CMM检验结果的比较,验证了原位检测方法的有效性。     

基于经验模态分解方法的曲面加工误差补偿

采用误差补偿技术对曲面的加工误差进行补偿是提高该类零件加工精度的有效方法。针对加工误差进行经验模态分解,将加工误差分解为若干个固有模态函数(IMF)和一个res趋势项函数。根据系统误差的特征,趋势项函数中一定存在系统误差,利用自相关分析法和频谱图对固有模态函数分析是否存在周期性变化系统误差,最终分解出系统误差和随机误差。搭建了数控机床在线检测的实验平台,实现了曲面零件的系统误差补偿。通过一个曲面零件的加工实验表明,补偿加工后的曲面精度提高了86.0%。仿真算例和实验结果表明,基于经验模态分解方法的加工误差补偿能有效提高曲面零件的加工精度。     

复杂曲面的数控加工误差分析

针对复杂曲面的多轴数控加工,应用数学知识建模,从理论上分析了平底铣刀刀具加工复杂曲面时的误差,得出了影响数控加工精度的主要因素并提出了误差补偿方法,为控制多轴数控加工的误差提供了理论依据与补偿算法,对高精度复杂曲面的数控加工具有借鉴意义。     

复杂曲面零件在线检测系统的开发与应用

复杂曲面零件特别是大型零件加工精度检测问题是先进制造技术领域急需解决的重要问题.数控机床在线检测技术则是实现被加工零件加工精度检测的新手段,因其方便、快捷、无需二次装夹,具有良好的应用前景.给出了面向复杂曲面零件加工精度在线检测的系统总体结构,描述了系统所包含的主要功能模块,给出了系统开发中需要解决的测点分布、测量路径生成与仿真、测量误差补偿等模块的实现方法和技术路线.     

复杂曲面零件数控加工的关键问题——解读《复杂曲面零件五轴数控加工理论与技术》

复杂曲面零件在航空、航天、能源和国防等领域有着广泛的应用,其制造水平代表着一个国家制造业的核心竞争力。五轴数控铣削加工具有高可达性、高效率和高加工精度等优势,成为复杂曲面零件的常用加工方式。在此背景下,毕庆贞、丁汉、王宇晗结合五轴数控铣削加工领域的实践经验和关键技术,共同撰写了《复杂曲面零件五轴数控加工理论与技术》一书,针对五轴加工中后置处理、刀具路径规划、路径光顺、误差检测与补偿、原位测量与自适应补偿等数字化制造的关键问题展开了详细叙述。     

航空薄壁件原位检测与补偿加工方法研究

航空结构件、航空叶片等薄壁零件是航空制造的关键零件,具有若刚性、材料难加工、工艺优化不足等特点,其加工精度难以控制。针对航空薄壁零件的在机测量与误差补偿方法展开研究,针对规则航空薄壁零件提出均值误差补偿方法,并在此方法的基础上延伸为针对自由曲面的分段误差补偿方法,最后对航空叶片进行了数控加工、原位检测及补偿加工实验,实验结果表明,补偿前后误差区间从0.15 mm~0.35 mm缩小到了-0.04 mm~0.06 mm,验证了分段误差补偿方法在加工几何偏差控制上的效果。     

空间曲面电火花线切割CAD/CAM系统

为解决高速走丝电火花线切割机床加工空间曲面的难题,实现大锥度空间复杂曲面零件的加工,以空间曲面数学模型和数控模型为基础,开发了一种计算机辅助设计/计算机辅助制造(Computer aided design/computer aided manufacturing,CAD/CAM)系统.其硬件系统以研制的数控转摆摆工作台为核心装置,并与现有高速走丝电火花线切割机床结合,组成空间曲面线切割加工系统.其软件系统可以根据上下导线的参数方程进行分析计算,建立空间曲面的三维模型,自动生成NC加工代码,进行加工仿真和空间曲面零件的加工.利用本系统进行典型空间复杂曲面零件的加工试验,结果表明加工结果与仿真结果基本相似.此外,还分析数控模型以及回摆间隙角对加工误差的影响.这些工作为解决高速走丝电火花线切割加工空间曲面的难题打下基础.     

精密数控机床主轴热伸长补偿技术研究

针对目前精密数控机床热误差补偿问题,在基于主轴热误差测量系统的基础上,提出一种基于FCM聚类、多元线性回归的热误差补偿模型。通过对某卧式加工中心主轴恒定转速和变速工况下进行温敏点测量,建立关键温敏点与机床主轴热伸长的几何关系,通过补偿结果和切削试验表明该方法可以有效地降低主轴热伸长误差,提升零件的加工精度。     

龙门式多轴联动机床的几何误差建模

设计一台集加工、检测于一体的小型龙门式多轴联动加工系统,以实现小型或微小型零件的铣、钻、磨削加工。机床除了从结构上提高精度外,也采取了误差补偿的措施,通过对机床进行几何误差建模,得到几何误差模型,以便进行补偿,提高精度。     

An integrated error compensation method based on on-machine measurement for thin web parts machining

Thin webs are widely used in the aerospace industry for the advantages of compact structure, light weight and high strength-to-weight ratio. Due to its low rigidity, serious machining error may occur, therefore, Finite Element method and mechanism analysis are usually utilized to modeling its deformation. However, they are very time-consuming and only suitable for elastic deformation error. In this study, an integrated error compensation method is proposed based on on-machine measurement (OMM) inspection and error compensation. The OMM inspection is firstly applied to measure the comprehensive machining errors. The Hampel filtering is then used to eliminate outliers, followed by the triangulation-based cubic interpolation as well as a machine learning algorithm which are used to establish the compensation model. At last, the real time compensation of high-density cutting points is realized by developing the compensation system based on External Machine Zero Point Shift (EMZPS) function of machine tool. Three sets of machining experiment of a typical thin web part are conducted to validate the feasibility and efficiency of the proposed method. Experiment results revealed that after compensation, the comprehensive machining errors were controlled under different machining conditions and 58.1%, 68.4% and 62.6% of the machining error ranges were decreased, respectively. This method demonstrates immense potential for further applications in efficiency and accuracy improvement of thin-walled surface parts.     

Prediction and compensation of machining geometric errors of five-axis machining centers with kinematic errors

Kinematic errors due to geometric inaccuracies in five-axis machining centers cause deviations in tool positions and orientation from commanded values, which consequently affect geometric accuracy of the machined surface. As is well known in the machine tool industry, machining of a cone frustum as specified in NAS979 standard is a widely accepted final performance test for five-axis machining centers. A critical issue with this machining test is, however, that the influence of the machine's error sources on the geometric accuracy of the machined cone frustum is not fully understood by machine tool builders and thus it is difficult to find causes of machining errors. To address this issue, this paper presents a simulator of machining geometric errors in five-axis machining by considering the effect of kinematic errors on the three-dimensional interference of the tool and the workpiece. Kinematic errors of a five-axis machining center with tilting rotary table type are first identified by a DBB method. Using an error model of the machining center with identified kinematic errors and considering location and geometry of the workpiece, machining geometric error with respect to the nominal geometry of the workpiece is predicted and evaluated. In an aim to improve geometric accuracy of the machined surface, an error compensation for tool position and orientation is also presented. Finally, as an example, the machining of a cone frustum by using a straight end mill, as described in the standard NAS979, is considered in case studies to experimentally verify the prediction and the compensation of machining geometric errors in five-axis machining.     

基于车削加工工件测量的误差补偿技术

提出两种基于车削工件测量的误差补偿方法 ,即误差反向叠加的微进给补偿法与逆变刀具路线的软件补偿法 ,介绍这两种方法的原理与实现方法     

An accurate probe pre-travel error compensation model for five-axis on-machine inspection system

On a five-axis CNC machine tool, the pretravel errors of touch-trigger probes are severely affected by gravity and must be compensated to ensure the required measurement accuracy. The situation is more complex than that of the three-axis on-machine inspection system. This paper proposes a simple and accurate modeling and compensation method for the probe pretravel error of a five-axis on-machine inspection system. First, the pretravel error for the 5-axis CNC tool is decoupled into three parts, which are analyzed based on the probe's mechanical structure. Then, a new calibration point selection strategy is proposed to obtain the accurate reference sphere center. Finally, we carry out calibration tests to validate the proposed method. The compensation results show that the proposed compensation method for the probe pretravel error under the influence of gravity (PPEUG) can improve the accuracy considerably.     

五轴数控机床几何误差建模方法研究

五轴数控机床是实现工件复杂表面精密加工的重要设备,而机床本身精度是保证加工精度的重要前提。以一台大型五轴数控加工机床为研究对象,分析各项误差,应用多体系统运动学理论,建立移动轴与旋转轴的几何误差数学模型,推导出刀具相对工件坐标系的位置与姿态误差表达式,为误差补偿提供精确数学模型,提高机床加工精度。     

A Novel Method of Efficient Machining Error Compensation Based on NURBS Surface Control Points Reconstruction

A novel method to improve the efficiency of error compensation in free-form surface machining based on the Non-Uniform Rational B-Splines (NURBS) surface control points reconstruction is proposed in this article. With the presented method, a relatively small number of inspection points are needed to be measured for error compensation. The machined surface is obtained by reconstructing the control points of the designed surface based on the on-machine measurement data. The machining error of the surface is obtained by calculating the difference between the machined surface and the designed one. Then a compensate surface is achieved using the mirror symmetry model and surface modification method to compensate the machining error. Experimental validation for the milling of a NURBS surface shows that the machining accuracy of the surface is improved by 62.57% through use of the proposed method.