【作者】 刘军；

【导师】 叶寒；

【作者基本信息】 南昌大学 ， 机械工程， 2024， 硕士

【摘要】 五轴加工中心作为高端机床装备,可以实现对复杂零件的高精度加工,提高制造灵活性,并降低生产成本,在现代制造业中扮演着不可或缺的关键角色。高速电主轴作为五轴加工中心的重要零部件,其在高速旋转时,会随着工作温度的不断升高,产生热变形现象,热伸长量将影响着加工零件的尺寸精度和表面质量。本文以国产某型号五轴加工中心上装备的电主轴为研究对象,通过理论计算,仿真分析和测量实验的方法研究电主轴在不同转速下的温度特性和受热变形现象,并设计基于电涡流式位移传感器的闭环补偿装置,利用西门子系统的机械原点偏移功能,实现对电主轴热误差的补偿。首先,分析电主轴内部主要结构,包括中心出水方式和混合陶瓷角接触球轴承等。在此基础上,进一步研究电主轴的生热及传热过程,详细计算电主轴的主要热源—电机和轴承的发热量及生热率,同时以传热学知识为基础,计算主要传热表面的传热系数。其次,拆装并测量电主轴各零件尺寸,利用Solid Works软件建立电主轴的三维模型,在ANSYS Workbench软件中设置模型的生热率和主要传热系数等边界条件,进行有限元分析,得到电主轴的稳态温度场和瞬态温度场,并建立电主轴的热-结构耦合仿真模型。研究发现电主轴在24000r/min和6000r/min时的最高温度分别为55.8℃和36.7℃,最大轴向热伸长量分别为44.9μm和28.1μm。进行电主轴热特性的实验研究,设计不同连续转速,利用K型热电偶测量电主轴三个位置温度,同时记录电机和冷却水的回液温度,通过雷尼绍对刀仪测量电主轴的轴向热伸长量,并将实验结果与仿真结果对比,验证了仿真结果的准确性。最后,提出一种基于电涡流位移传感器的闭环补偿装置,通过电涡流位移传感器实时检测电主轴被测表面的位移值,建立传感器与数控系统的通信,利用西门子数控系统的机械原点偏移功能进行热补偿。进行不同转速下空载补偿实验得出补偿后的电主轴热伸长量减少了60%至70%左右。进行平面加工验证实验,铣削边长为180mm的方形平面,发现补偿后的加工平面的平面度在10μm以内。为了提高装置补偿的准确性,对位移传感器采集的位移数据进行限幅滤波、均值滤波和高斯滤波,可有效地去除由转速变化引起的数据凸起,并降低位移数据波动。更多还原

【Abstract】 As a high-end machine tool equipment,the five-axis machining center can realize high-precision machining of complex parts,improve manufacturing flexibility,and reduce production costs,which plays an indispensable role in modern manufacturing.As an important part of the five-axis machining center,the high-speed electric spindle will produce thermal deformation with the continuous rise of the working temperature when rotating at high speed,and the thermal elongation will affect the dimensional accuracy and surface quality of the machined parts.In this paper,the electric spindle equipped on a domestic five-axis machining center is taken as the research object,and the temperature characteristics and thermal deformation phenomenon of the electric spindle at different speeds are studied by theoretical calculation,simulation analysis and measurement experiment.A closed-loop compensation device based on eddy current displacement sensor is designed to compensate the thermal error of electric spindle by using the mechanical origin offset function of Siemens system.Firstly,the main internal structure of the electric spindle is analyzed,including the center outlet mode and the mixed ceramic angular contact ball bearing.On this basis,the heat generation and heat transfer process of the electric spindle is further studied,and the heat generation and heat generation rate of the main heat source of the electric spindle-motor and bearing are calculated in detail.At the same time,the heat transfer coefficient of the main heat transfer surface is calculated on the basis of heat transfer knowledge.Secondly,disassemble and measure the dimensions of each part of the motorized spindle,establish the three-dimensional model of the motorized spindle with Solid Works software,set the boundary conditions of the model such as heat generation rate and main heat transfer coefficient in ANSYS Workbench software,and conduct finite element analysis to obtain the steady-state temperature field and transient temperature field of the motorized spindle.The thermal-structural coupling simulation model of the motorized spindle is established.It is found that the maximum temperature of the motorized spindle at 24000r/min and 6000r/min is55.8℃and 36.7℃respectively,and the maximum axial thermal elongation is44.9μm and 28.1μm,respectively.The experimental study on the thermal characteristics of the motorized spindle was carried out,different continuous speeds were designed,the temperature of the three positions of the motorized spindle was measured by K-type thermocouple,and the liquid return temperature of the motor and cooling water was recorded at the same time.The axial thermal elongation of the motorized spindle was measured by Renishaw cutter.The experimental results are compared with the simulation results to verify the accuracy of the simulation results.Finally,a closed-loop compensation device based on eddy current displacement sensor is proposed.Through the eddy current displacement sensor,the displacement value of the measured surface of the spindle is detected in real time,and the communication between the sensor and the CNC system is established.The mechanical origin offset function of Siemens CNC system is used for thermal compensation.The no-load compensation experiment at different speeds shows that the thermal elongation of the compensated motorized spindle is reduced by about60%to 70%.The surface machining verification experiment was carried out.The square plane with a side length of 180mm was milling.It was found that the flatness of the compensated machining plane was less than 10μm.In order to improve the compensation accuracy of the device,limiting filtering,mean filtering and Gaussian filtering are applied to the displacement data collected by the displacement sensor,which can effectively remove the data bump caused by the speed change and reduce the displacement data fluctuation.更多还原