基于光纤光栅传感的重型机床立柱热变形监测研究

发布时间：2018-06-25 04:39

本文选题：光纤光栅传感 + 重型机床立柱　；参考：《武汉理工大学》2015年硕士论文

【摘要】：重型数控机床在加工制造业中扮演着相当重要的角色,提高其加工精度一直是备受关注的重要研究课题。研究表明,热误差占机床总误差的45%左右,同时精度要求越高,其所占比重越大。为了能减少或后期抵消热误差,目前对热误差的研究主要集中在机床温度场分析、温度变化与热变形建模等方面。由于机床是个复杂的物理结构,并且存在外界环境的不可控干扰,温度场难以重构,而所建模型的精确性、鲁棒性和运算效率也影响着热误差补偿装置的效果。机床热误差是机床各部件在热源影响下产生形变的共同作用效果,而热变形建模是热误差补偿技术的基础,通过所建模型可以根据实时温度变化预测并补偿形变量而实现热误差的减少。从物理结构上看,立柱的弯曲会引起横梁前倾,从而导致加工主轴发生热漂移。本文以机床的大型构件—立柱为研究对象,围绕其与机床热变形之间的关系开展了如下工作:(1)对机床的热源分布进行分析,运用光纤光栅温度传感器针对立柱的温度场进行了初步测量,同时运用CCD激光位移传感器同步采集主轴热漂移(机床Y方向热变形),并对立柱温度变化与热变形数据之间的相关性进行分析。(2)并非所有温度测点与热变形之间有明显关系,因此运用模糊聚类方法对温度测量点进行分组,然后以不同的侧重点,分别采用偏相关分析、最大灵敏度和灰关联分析方法从分组中筛选出关键温度测量点,并基于筛选结果存在交叉性,提出一种更为平衡的综合测点优化策略。(3)基于所得到的关键温度测量点分别运用多元线性回归模型、BP神经网络模型和基于遗传算法改进的BP网络模型建立其与机床热变形的关系模型,并对模型进行评估得到最佳的预测模型。同时根据评估结果也验证了不同测点优化策略的优劣,进而提出测点优化和建模方法改进的建议。(4)为了更方便和深入的研究立柱形变对机床热误差的影响机理,基于光纤光栅的应变量测量,推导了柱形结构应变量与自身形变状态之间的关系。同时设计了柱形结构二维形变实时监测模型和实现方案,运用该模型能够在线监测机床柱形结构的弯曲变化特点,对后续热误差补偿的研究甚至是柱形结构的设计都有重要参考意义。
[Abstract]:Heavy CNC machine tools play a very important role in the manufacturing industry, and improving their machining accuracy has been an important research topic. The results show that the thermal error accounts for about 45% of the total error of the machine, and the higher the precision is, the greater the proportion of the thermal error is. In order to reduce or offset the thermal error, the research on the thermal error is mainly focused on the analysis of the temperature field of the machine tool, the modeling of the temperature change and the thermal deformation, etc. Because the machine tool is a complex physical structure and there exists uncontrollable disturbance in the external environment, it is difficult to reconstruct the temperature field, and the accuracy, robustness and operational efficiency of the established model also affect the effect of the thermal error compensation device. The thermal error of machine tool is the common effect of deformation produced by the components of machine tool under the influence of heat source, and the thermal deformation modeling is the basis of thermal error compensation technology. The thermal error can be reduced by predicting and compensating the shape variables according to the real time temperature change. From the point of view of physical structure, the bending of the column will cause the beam to lean forward and cause the heat drift of the machining spindle. In this paper, a large component of machine tools-columns as the research object, around the relationship between the thermal deformation of the machine tools carried out the following work: (1) the distribution of heat sources of machine tools are analyzed. The temperature field of the column is preliminarily measured by using the fiber Bragg grating (FBG) temperature sensor. At the same time, CCD laser displacement sensor is used to synchronously collect the thermal drift of spindle (thermal deformation in the Y direction of machine tool), and the correlation between the temperature change of the column and the thermal deformation data is analyzed. (2) not all the temperature measuring points have obvious relationship with the thermal deformation. Therefore, the temperature measurement points are grouped by fuzzy clustering method, and then the key temperature measurement points are selected from the grouping by using the partial correlation analysis, the maximum sensitivity and the grey correlation analysis, respectively, with different emphases, and the method of maximum sensitivity and grey correlation analysis is used to select the key temperature measurement points from the groups. And based on the results of the screening, A more balanced optimization strategy for integrated measurement points is proposed. (3) based on the obtained critical temperature measurement points, the multiple linear regression model / BP neural network model and the improved BP neural network model based on genetic algorithm are used to establish the computer respectively. The relation model of bed thermal deformation, The best prediction model is obtained by evaluating the model. At the same time, according to the evaluation results, the merits and demerits of different measuring points optimization strategies are verified, and the suggestions for improving the measurement point optimization and modeling methods are put forward. (4) in order to study the influence mechanism of column deformation on the thermal error of machine tools more conveniently and deeply, Based on the strain measurement of fiber grating, the relationship between the strain of cylindrical structure and its deformation state is derived. At the same time, the real time monitoring model and realization scheme of two-dimensional deformation of cylindrical structure are designed. The model can be used to monitor the bending characteristics of cylindrical structure of machine tools on line. It is of great significance to study the subsequent thermal error compensation and even the design of cylindrical structure.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG659

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