提高轮廓加工误差联机检测精度的研究

在数控机床或加工中心上采用联机检测轮廓加工误差的方法，不用价格昂贵的坐标测量机，具有简单、省时、经济的特点。文章分析了数控机床或加工中心的直线运动误差对联机检测轮廓加工误差精度的影响，并测量出了加工中心的几何运动误差，提出了消除机床几何运动误差影响，提高轮廓加工误差联机检测精度的方法。实验结果表明，所采用的方法可以明显提高轮廓加工误差联机检测精度。     

基于刚度分析的中心架设置有限元优化设计

针对在磨削细长轴时,出现中心架数量以及支撑位置的确定问题,凭借当前经验和加工中进行补偿等方法,提出应用有限元分析优化的方法,借助ANSYS Workbench软件选择满足加工要求的中心架设置方案。对两端顶尖夹紧定位方式进行了载荷和约束分析,以让刀量为优化目标,建立了优化数学模型,提出适合ANSYS Workbench软件的寻优方法;通过对长900 mm、30 mm的光轴参数化建模和分析优化,分析出无中心架时让刀量的变化规律,以及在一个中心架、两个〖JP2〗中心架下让刀量最优时的位置方案,并对分析结果进一步验证,得出3种方案下的前6阶模态振型和模态频率。实验结果表明：该分析结果和实际加工中的选择方案一致,说明该方法的可行性,为细长轴加工中心架的设置提供了一种可行的方法。     

Durability evaluation of software error correction on a machining center

Machine tool software error correction has been successfully demonstrated in laboratories for at least the last 20 years. However, no results could be found that evaluate the durability of such an approach. To be cost beneficial for industry, the time consuming measurement procedure needs to be as infrequent as possible. This study attempts to quantify the durability of such an approach on a commercial 3-Axis machining center. A traditional correction model is created and implemented inside the control system along with a first order thermal correction of the scales. Measurements are made with the Laser Ball Bar, which minimizes data collection to less than 30 min. The compensation system was evaluated over a 9 month period in which the machine experienced normal machining and common mishaps (tool crash). The results show that during this 9 month period, the compensation system was still capable of significantly reducing the machine's inherent errors.     

精密加工中心主轴热误差测量技术的研究

热误差是影响精密加工中心加工精度的主要因素之一,因此减小热误差对提高加工中心的精度至关重要.通过对热误差进行检测、建模,可以从一定程度上消除热误差对精密加工中心的影响,提高加工精度.文章以精密立式加工中心VDM55为研究对象,在分析热误差来源及形式的基础上,利用研制的温度和热误差检测系统,测量了加工中心主轴温度场和热误差.该测量系统具有成本低、测量精度高、结构简单的特点.通过合理设计的热误差测量实验,获得了真实有效的主轴热误差数据.测量数据的分析结果表明,该方法对研究机床热误差规律和建模具有很大的应用价值.     

基于热误差补偿的加工中心在线检测软件的研究

对加工中心在线检测软件误差补偿技术进行研究,基于Windows平台开发了在线检测误差补偿软件,并对软件开发中的关键技术：建立检测系统的几何误差与热误差综合模型,测头误差处理技术进行了研究。该检测软件可以同时对测头误差、机床几何误差与热误差进行补偿,有效地提高了在线检测精度。软件系统在MAKINO立式加工中心上进行丁实验验证。     

基于激光的立铣刀圆角半径测量误差补偿方法

数控加工中心在使用激光对刀仪测量立铣刀圆角半径时，即使经过精度调整和标定依然存在系统误差。分析激光对刀仪测量立铣刀圆角半径的原理，提出激光遮蔽误差是产生该系统误差的主要因素；建立激光遮蔽误差补偿表达式，进行实验验证。结果表明：补偿后测量误差从0.08 mm降低到0.02 mm，证明了该补偿方法的实用性。     

基于AutoCAD的加工中心在线工件自动检测系统

介绍了基于AutoCAD的加工中心在线工件自动检测系统的构成及功能.在ObjectARX的开发环境Visual C 6.0下,对AutoCAD二次开发提取检测数据,制定检测工艺规划,自动生成检测程序.该系统可用于工件的装夹找正,对工件进行自动在线测量、数据处理及质量分析,并能对加工误差进行补偿,以提高加工精度.     

精密卧式加工中心空间误差的建模、测量与补偿技术

采用空间误差补偿技术,可有效提高数控机床的空间定位精度。以一台精密卧式加工中心为对象,系统阐述其几何误差补偿中的关键问题及解决方案。通过三维误差建模与分析,得到该机床的21项几何误差中有17项需要测量和补偿,另外4项误差对机床定位精度的影响甚微。以此为依据,设计误差测量及补偿方案,并给出误差的具体测量方法和补偿结果。结果表明:经过一次系统地误差测量与补偿,精密卧式加工中心的空间定位精度可以提高50%～70%;合理规划和实施空间误差测量,可大幅提高测量效率。     

Novel compensation of axial thermal expansion in ball screw drives

Novel functional materials in the field of machine tools such as shape memory alloys are capable to convert thermal energy into mechanical energy by generating work. Besides, their self-sensing properties and high energy density make them suitable to compensate thermal deformations. Manufacturing requirements concerning machine tools and machining centers can be summarized in a high productivity, a high reliability (low-maintenance) and a high accuracy/precision. The latter machine design parameter depends almost on linear drive systems, which are responsible for the relative distance between workpiece and tool center point. Their positioning performance is limited, among others, to changes in thermal conditions; even with cooling systems that represent about 90 % of the overall energy consumption of the machine. Therefore, thermal errors in machine tools are currently an issue to overcome. Within the scope of this work, shape memory alloys have been integrated in ball screw drives in order to achieve a thermal stable machine transmission component.     

Derivation of machine tool error models and error compensation procedure for three axes vertical machining center using rigid body kinematics

Volumetric positional accuracy constitutes a large portion of the total machine tool error during machining. In order to improve machine tool accuracy cost-effectively, machine tool geometric errors as well as thermally induced errors have to be characterized and predicted for error compensation. This paper presents the development of kinematic error models accounting for geometric and thermal errors in the Vertical Machining Center (VMC). The machine tool investigated is a Cincinnati Milacron Sabre 750 3 axes CNC Vertical Machining Center with open architecture controller. Using Rigid Body Kinematics and small angle approximation of the errors, each slide of the three axes vertical machining center is modeled using homogeneous coordinate transformation. By synthesizing the machine's parametric errors such as linear positioning errors, roll, pitch and yaw etc., an expression for the volumetric errors in the multi-axis machine tool is developed. The developed mathematical model is used to calculate and predict the resultant error vector at the tool–workpiece interface for error compensation.     

Integrated planning for precision machining of complex surfaces—III. Compensation of dimensionai errors

This paper presents an approach that compensates machining errors in ball-end milling processes using the control-surface strategy. In the proposed approach, machining errors induced by cutter deflections are predicted from a surface generation model so that actual machining experiments and dimensional inspections are not required. Therefore, the proposed approach can be integrated into an integrated framework for machining planning in which prediction and compensation of dimensional errors take place in the process development phase rather than in the manufacturing phase of the production cycle. Based on the predictive capability of the surface generation model, a sensitivity function is defined so as to characterize the variations of the machining errors when perturbing the control surface. Using the defined sensitivity function, a compensated control surface can be constructed, based on which new cutting paths can be planned and “near-zero” surface dimensional errors can be accomplished. In order to verify the proposed strategy, actual production of a turbine blade die using a CNC machining center was conducted. By using the control-surface strategy with the sensitivity function approach, the maximum surface dimensional error is reduced from ± 340 to ± 10 μm.     

能够进行热误差补偿的加工中心在线检测软件的研究

研究了加工中心在线检测软件误差补偿技术，基于Windows平台开发了误差补偿软件，并对软件开发中的关键技术：建立检测系统的几何误差与热误差综合模型，测头误差处理技术进行了研究。可以同时对测头误差、机床几何误差与热误差进行补偿，有效地提高了在线检测精度。软件系统在MAKINO立式加工中心上进行了实验验证。     

加工中心几何误差建模分析与误差补偿策略

运用齐次坐标变换原理和刚体假设，建立了加工中心从刀点到工作台的总体误差传递矩阵，推导出了通用的加工中心几何误差计算模型；用此模型对TH6350卧式加工中心进行了几何误差计算，并对误差模型进行了校验和分析，提出了基于PC机的加工中心误差补偿策略。     

四轴联动加工中心几何误差软件补偿技术研究

以多体系统理论为基础,通过分析位移变换矩阵和位置变换矩阵,建立了四轴联动加工中心的几何误差模型.基于Windows平台开发了误差补偿软件,可以对测量数据进行机床几何误差的软件补偿,有效地提高了在线检测精度.软件系统在MAKINO立式加工中心上进行了实验验证,补偿效果明显.     

故障比重比在数控机床故障分析中的应用

在传统故障频次分析方法的基础上,应用故障比重比对所采集的某系列加工中心现场故障信息进行了统计分析,找出了影响该加工中心可靠性的薄弱环节,进一步明确了加工中心可靠性改进工作的主攻方向,弥补了以往只通过故障频次图分析故障信息的缺陷,为其它机电产品的可靠性研究提供了较实用的方法.     

A study of pre-compensation for thermal errors of NC machine tools

Thermally-induced errors are major contributors to the overall accuracy of machine tools. In this paper, an error pre-compensation system is developed to correct the thermal errors of the spindle and lead screws. A simple gauge 1-D ball array is used to accelerate and simplify the error measurement. An auto-regressive model based on spindle rotation speed is then developed to describe the thermal errors. Using the model, the thermal errors can be predicted without measuring the temperature field of the machine tool as soon as the workpiece NC machining program is made. By correcting the program, the errors can be pre-compensated before machining. Thus the process of compensation is greatly simplified and the cost is reduced. The test results on a vertical machining center show that a 70% reduction of thermal errors has been gained after compensation.     

立式加工中心空间误差验证及补偿

为提高某立式加工中心整机加工精度,借助旋量理论建立完备立式加工中心空间误差模型,在此基础上实现机床空间误差有效补偿.以旋量理论为基础推导并建立机床刀具运动链与工件运动链运动学正解,分析机床21项几何误差原理,在考虑21项几何误差的基础上建立该立式加工中心完备空间误差模型;利用九线法完成各项几何误差辨识;基于旋量运动学正解求解机床运动学逆解后得出运动轴实际运动路径,并通过体对角线实验对比补偿前后的效果.结果表明:所提补偿方法补偿效果显著,验证了机床空间误差模型的准确性,实现了提高机床加工精度的目的.     

Integrated machining error compensation method using OMM data and modified PNN algorithm

This paper presents an integrated machining error compensation method based on polynomial neural network (PNN) approach and inspection database of on-machine-measurement (OMM) system. To improve the accuracy of the OMM system, geometric errors of the CNC machining center and probing errors are compensated. Machining error distributions of a specimen workpiece are measured to obtain error compensation parameters. To efficiently analyze the machining errors, two machining error parameters, W_err and D_err, are defined. Subsequently, these parameters can be modeled using the PNN approach, which is used to determine machining errors for the considered cutting conditions. Consequently, by using an iterative algorithm, tool path can be corrected to effectively reduce machining errors in the end-milling process. Required programs are developed using Ch language, and modified termination method are applied to reduce computation times. Experiments are carried out to validate the approaches proposed in this paper. The proposed integrated machining error compensation method can be effectively implemented in a real machining situation, producing much fewer errors.     

提高卧式加工中心可靠性的措施

当前国产卧式加工中心的可靠性与进口产品存在较大差距,这已成为影响国产卧式加工中心口碑和市场的关键因素。通过深入分析某公司生产的14台卧式加工中心在用户现场的故障数据,查清机床整机各故障部位、故障模式及故障原因的概率,找出对整机可靠性影响较大的故障模式和故障原因,并据此提出提高国产卧式加工中心机床可靠性的措施。     

机床变形速度对滚齿加工精度的影响

滚齿加工中,滚刀与工件的相对位置会产生偏差。本文对刀具相对工件在各个方向的位移偏差变化速度与加工齿轮精度间的关系进行了讨论。结果表明,滚刀与工件间的相对偏差变化速度的快慢不仅影响到齿轮加工精度,还影响到误差补偿方法的选取。研究结果对于改进机床设计、减小加工偏差、实现机床的偏差补偿有一定的理论和实际意义。