数控机床误差补偿技术及热误差补偿技术

热变形误差是影响机床定位精度的重要因素之一，文章在分析我体系统基本变换的基础上，建立了计及几何误差，载荷误差和热变形误差的机床不空间综合误差计算模型。对ＸＨＦＡ２４２０加工中心的丝杠和滑枕系统的热变形误差进行了和补偿，实验结果表明热误差补偿量达６５％以上。     

重型数控机床热学模型及热误差补偿技术研究

研究了重型数控机床主轴系统温度场及主轴热变形误差,分别测试了机床不同工况下的温升情况及主轴三个方向上的热变形。基于测试数据获取了机床主轴热变形的变化规律,并建立起了机床的热误差建模预测模型,针对西门子840D系统的补偿模块,应用预测模型实现对热误差的补偿并进行了实验验证。     

基于外部机床坐标系偏移的热误差实时补偿

基于数控系统的外部机床坐标系偏移功能，通过修改数控系统中的PLC程序，将数控机床的热变形误差，即工件与刀具间的相对热运动值读入数控系统，利用外部机床坐标系的偏移而实现热误差的实时补偿，开发研制了高精度、低成本、满足实际要求的热误差实时补偿系统。经实际生产应用，机床的加工精度得到了大幅度提高。     

卧式数控机床主轴温度场分布及对机床热变形的影响

分别应用红外热像仪测温技术和激光测距技术对机床温度场和机床热误差开展研究.着重分析三轴卧式数控机床的温度场分布、机床运行中的热行为以及两者之间的联系.经试验发现,主轴热误差是数控机床的主要误差源之一,主轴热误差与机床运行中的温度分布有紧密联系,主轴各方向变形量呈现出随主轴温度升高而明显增大趋势,并且主轴Z方向的伸长量远大于X和Y向的变形量.提出通过改善冷却和散热条件而降低主轴温度,以达到有效控制主轴热误差以及建立热变形补偿模型实施补偿等措施,经验证热变形改善效果明显.     

两种膨胀系数热变形计算误差分析

本文从热膨胀系数基本定义出发对热变形计算进行了较深入分析。理论上建立了平均线膨胀系数同瞬间线膨胀系数计算热变形的误差数学模型 ,并通过实验论述了精密工程应用中使用平均线膨胀系数计算的工件热变形误差较大 ,提出广泛使用瞬间热膨胀系数替代平均线膨胀系数是提高机器设备精度的发展趋势。     

数控机床温度与热误差检测系统

数控机床热变形补偿模型研究和应用中须快速采集大量温度与热误差信号.针对温度和热误差信号的特点开发了检测系统,此系统具有方便快速测量机床各部位温度和机床热误差的功能.     

全工况齿轮传动振动特性的研究

本文提出了在齿轮装置热系统下求解齿轮本体温度分布的方法。并根据本体温度上升导出轮齿的热变形。将热变形考虑为对齿轮正确轮廓的误差，考察了综合热变形误差对齿轮振动特性的影响，本文系重庆大学机械传动国家重点实验室基金资助项目。     

精密测量中零件热变形系数研究

本文提出了零件热变形系数的概念，初步研究了现代高精度测量中热变形系数与热膨胀系数之间的关系以及对测量精度的影响，指出了传统的热变形误差计算方法严重不足之处，阐明了形体边界条件在零件高精度热变形计算中的影响问题。     

基于热态特性仿真的龙门铣床主轴系统热关键点选择方法

数控机床主轴系统热误差建模的难点之一，是使用少量的热关键点建立热误差的精确模型。文章以一台龙门铣床为研究对象，首先通过有限元法仿真分析了机床主轴系统的温度场、热应力、热模态和热变形，根据仿真结果在主轴系统上选择了3个热关键点；然后试验测量了热关键点的温度变化和主轴系统沿x、y、z向的热变形；最后通过多元线性回归模型建立了主轴系统的热误差模型。结果表明：x、y、z向热误差模型的拟合精度都超过95%，证明了文章主轴系统热关键点选择方法的正确性。     

数控机床主轴热变形伪滞后研究及主轴热漂移在机实时补偿

为研究数控机床热变形规律,实现数控机床误差在机实时补偿,进行数控机床主轴热变形理论及试验分析,结果表明,数控机床主轴热变形与主轴温变在距热源约1/3位置存在近似线性关系,即主轴热变形存在伪滞后现象,这一结果为数控机床测温点优化布置及热误差鲁棒建模提供理论依据。为验证机床热变形伪滞后现象,对VM850加工中心主轴热漂移误差在机实时检测并建模,通过自主研发数控机床误差在线实时补偿系统对主轴热漂移误差进行实时补偿,经补偿,机床主轴热漂移误差减少90%以上,有效提高了数控机床主轴精度。     

量化误差对周期信号总失真度评价的影响及修正

讨论了量化误差对周期信号失真度测量评价结果的影响,详细阐述了两者之间的关系,并给出了量化误差对周期信号失真度测量造成的影响及其修正关系的数学公式。在正弦波失真度评价中进行的仿真实验结果,验证了本文结论及过程的正确性及切实可行性。     

Equivalent thermal conductivity of heat pipes

In precision machining, the machining error from thermal distortion carries a high proportion of the total errors. If a precision machining tool can transfer heat fast, the thermal distortion will be reduced and the machining precision will be improved. A heat pipe working based on phase transitions of the inner working liquid transfers heat with high efficiency and is widely applied in spaceflight and chemical industries. In mechanics, applications of heat pipes are correspondingly less. When a heat pipe is applied to a hydrostatic motorized spindle, the thermal distortion cannot be solved during the heat transfer process because thermal conductivity or equivalent thermal conductivity should be provided first for special application in mechanics. An equivalent thermal conductivity model based on equivalent thermal resistances is established. Performance tests for a screen wick pipe, gravity pipe, and rotation heat pipe are done to validate the efficiency of the equivalent thermal conductivity model. The proposed model provides a calculation method for the thermal distortion analysis of heat pipes applied in the motorized spindle.     

振镜二维扫描的图形畸变校正和曝光量补偿

主要讨论了物镜前振镜二维扫描光学系统中图形畸变的产生原因,分析比较了图形畸变与振镜布放、像面坐标系方位及fθ特性误差等的关系,并结合视场大小为75×75的实际物镜fθ特性误差的最小二乘拟合,给出了校正图形畸变的准确关系式.另外,在矢量扫描方式中光斑移动速度的非线性会导致扫描图形各部分曝光不均匀,文中也给出了对扫描图形曝光量加以补偿的方法和公式.     

用热电偶测量薄板温度时的导热误差分析

用热电偶测量恒热流条件下薄板的温度时,沿热电偶丝的热量导出将引起接触区域的温场畸变,从而产生导热误差。本文对该导热误差公式进行了详细推导,分析了影响导热误差的各种因素,并且提出了减小导热误差的方法。     

Improving waviness of bore in precision hard turning by pressurized coolant

Precision hard turning is an emerging innovated machining technology for machining hardened workpiece (60~62 HRC) with characteristic of better flexibility, high production rate, and cost saving. However, one of problem in this process is that it is difficult to remove the thermal distortion of the workpiece induced by the heat generated during the process, especially in the case of precision hard turning of bore. In this paper, pressurized coolant was used in a precision hard turning of bore, with polycrystalline cubic boron nitride as the tool materials, to reduce the thermal distortion of the machined part such as form error and to improve its waviness. The pressurized coolant jet was directly delivered under the chip on the rake face. Experimental result indicated that form error induced by the heat has been reduced, and waviness of the bore was improved with use of pressurized coolant. Crater wear is smaller under pressurized coolant compared to dry cut due to lower rake face temperature and shorter contact length between chip and workpiece.     

Investigations on welding residual stress and distortion in a cylinder assembly by means of a 3D finite element method and experiments

In the present work, both experimental and numerical simulation methods are used to investigate the characteristics of welding distortion and residual stress distribution. A 3D thermo-mechanical Finite Element Analysis (FEA) method is used to predict the welding distortion and residual stress of cylinder-shaped multi-pass layer weldments. Each weld pass is performed using a quarter-circle balanced welding procedure. To investigate the influence of deposition sequence and welding heat input on the welding distortion and residual stress, a continuous welding procedure is also calculated. The corresponding FEA models considered a moving heat source, the deposition sequence, and temperature-dependent thermal and mechanical properties. The results predicted by 3D FEA model are generally in good agreement with the measurements. Finally, the numerical and experimental results suggest that both deposition sequence and heat input affect welding distortion and residual stress distribution. Furthermore, the 3D thermal-mechanical FEA method can predict cylinder-type welding distortion.     

锂离子动力电池组发热功率试验研究

锂离子动力电池的性能和寿命与电池热管理密切相关,而电池产热模型的建立是其热管理的基础。通过理论计算、试验测试和模拟分析对额定容量为50 A·h、额定电压为3.65 V的三元锂离子动力电池的充放电发热特性进行了研究。结果表明:Newman公式在电池发热功率计算中准确度较高,与试验测得发热功率相比误差为8.7%。将理论发热功率应用于模拟仿真后,模组最高温度与试验测得最高温度误差为9.5%,模拟结果可为锂电池的性能研究及热管理设计提供参考。     

透视投影变换中椭圆中心畸变误差模型及其仿真研究

针对在三维视觉检测应用中，空间椭圆中心的透视投影变换存在畸变误差的问题进行了研究。基于透视投影变换和空间解析几何理论，建立了在摄像机的像平面上该畸变误差的数学模型，并进行了仿真研究，获得了该畸变误差的变化规律，从而为圆孔(椭圆孔)或圆柱(椭圆柱)类工件的中心位置的视觉检测、结构光三维视觉检测应用及视觉检测中的CCD摄像机内部参数标定等问题的有效解决，提供了一个有效的理论依据，具有一定的理论意义和工程实际应用价值。     

Consideration of residual stress and geometry during heat treatment to decrease shaft bending

In automotive industry, heat treatment of components is implicitly related to distortion. This phenomenon is particularly obvious in the case of gearbox parts because of their typical geometry and precise requirements. Even if distortion can be anticipated to an extent by experience, it remains complex to comprehend. Scientific literature and industrial experience show that the whole manufacturing process chain has an influence on final heat treatment distortions. This paper presents an approach to estimate the influence of some factors on the distortion, based on the idea of a distortion potential taking into account not only geometry but also the manufacturing process history. Then the idea is developed through experiments on an industrial manufacturing process to understand the impact of residual stress due to machining on shaft bending and teeth distortion during heat treatment. Instead of being measured, residual stress is being neutralized. By comparing lots between each other, connections between gear teeth geometry and manufacturing steps before heat treatment are obtained. As a consequence, geometrical nonconformities roots can be determined more easily thanks to this diagnosis tool, and corrective actions can be applied. Secondly, the influence of product geometry on bending is experimentally considered. Moreover, metallurgical observations enable to explain the influence of workpieces geometry on shaft bending. Thanks to the obtained results, process and product recommendations to decrease shafts bending are proposed.     

虚拟NC车削加工过程中刀具变形研究

对刀具变形影响的相关因素作了深入的研究,建立了相应的数学模型,首次提出了利用悬臂梁的理论来计算刀具的受力变形,并且进行了一系列的公式推导,合理地对刀具的受热变形和受力变形进行了矢量叠加。利用VC++编程,实现了NC加工过程中刀具变形的预测与显示。