【作者】 李涛；

【导师】 杨军良； 白云飞；

【作者基本信息】 西安理工大学 ， 机械工程（专业学位）， 2021， 硕士

【摘要】 蓝宝石晶体作为一种物理、化学性质突出的晶体材料,在半导体照明、微电子、手表手机镜面、国防工业等领域得到了广泛的应用。随着蓝宝石晶体用途越来越广,市场对蓝宝石晶体的需求也越来越大,尺寸要求越来越大,品质要求越来越高,因此,当前需要改进蓝宝石晶体生长工艺,提高生长设备的自动化程度,降低生产成本来满足上述要求。本文对比分析了几种当今主流的蓝宝石晶体生长工艺,确定选用改良泡生法——冷心放肩微量提拉法作为本次生长蓝宝石晶体的工艺方法,从能量守恒的角度,针对蓝宝石晶体生长的等径控制和生长速率方面进行了分析,初步确定了晶体控径方法。对泡生法蓝宝石晶体生长设备的整体方案进行了设计,并对各个系统的组成及功能进行了分析,重点研究了上传动及称重系统。对三种主流的晶体控径技术进行了对比分析,选用上称重控径技术符合本次设计要求,分析了上称重等径控制的原理,更进一步得到了泡生法蓝宝石晶体等径控制的方法。上传动系统主要包含籽晶杆的旋转和提拉运动,为保证籽晶杆在运行过程中长期保持低速、无抖动、无爬行、控制精准的要求,对上传动系统的机械结构进行了设计,并根据上传动控制系统原理,设计了运动控制的硬件接线图,对运动控制系统进行了搭建。称重传感器是称重系统的核心部件,通过对比称重传感器类型,确定选用电阻应变片式称重传感器更具优势,对其工作原理进行了分析。并对三组不同孔径的称重传感器弹性体采用ANSYS Workbench软件进行满负载状况下静力学仿真,根据其贴片区域的应力曲线以及弹性体变形特性,为应变片贴片区域的确定和传感器固定方式的选择提供理论指导;通过分析对比不同布置方式的下籽晶杆偏移量,为称重传感器实际布置方式的选择提供数据参考。生长设备在运行过程中分为空载和负载两种工况,为了得到上传动及称重系统在实际运行过程中的运动特性,就需要对其结构进行模态分析,得到其相应的模态参数(固有频率和模态振型),为避免设备运行出现共振并为设备故障分析提供数据参考。根据泡生法蓝宝石晶体生长工艺特点建立了晶体生长模型,利用MATLAB软件编写了模型脚本。在晶体实际生产之前,需提前设计好晶体外形尺寸,通过向脚本中输入蓝宝石晶体相关的尺寸参数,得到晶体生长的理想生长曲线,对实际晶体的生长过程进行指导。采用MATLAB软件中的Simulink仿真模块分别建立了常规PID控制和模糊PID控制仿真框图,对比仿真结果发现模糊PID控制算法在系统控制的稳定性、响应性和抗干扰能力都比常规PID控制算法略胜一筹,控制效果更佳,为实际控制算法的选取提供理论指导。更多还原

【Abstract】 As a crystal material with outstanding physical and chemical properties,sapphire crystal has been widely used in the fields of semiconductor lighting,microelectronics,watch and mobile phone mirrors,and national defense industry.As sapphire crystals are used more and more widely,the market demand for sapphire crystals is also increasing,the size requirements are increasing,and the quality requirements are getting higher and higher.Therefore,it is currently necessary to improve the sapphire crystal growth process and improve the growth equipment.The degree of automation can reduce production costs to meet the above requirements.This article compares and analyzes several current mainstream sapphire crystal growth processes,and decides to choose the improved Kyrgyzstan method-the cold-hearted micro-lifting method as the process method for growing sapphire crystals.From the perspective of energy conservation,the iso-diameter control and growth rate of sapphire crystal growth were analyzed,and the crystal diameter control method was initially determined.The overall scheme of the Kyrgyzstan method sapphire crystal growth equipment was designed,and the composition and function of each system were analyzed,with emphasis on the upper transmission and weighing system.The three mainstream crystal diameter control technologies were compared and analyzed,and the upper weighing diameter control technology was selected to meet the design requirements of this time.The principle of the upper weighing equal diameter control is analyzed,and the method for equal diameter control of the Kyropoulos sapphire crystal is further obtained.The upper drive system mainly includes the rotation and lifting motion of the seed rod.In order to ensure that the seed rod maintains a low speed,no jitter,no crawling,and precise control requirements during operation,the mechanical structure of the upper drive system is designed.And according to the principle of the upper transmission control system,the hardware wiring diagram of the motion control is designed,and the motion control system is built.The load cell is the core component of the weighing system.By comparing the types of the load cell,it is determined that the resistance strain gauge type load cell is more advantageous,and its working principle is analyzed.And use ANSYS Workbench software to perform statics simulation under full load for three groups of load cell elastomers with different apertures.According to the stress of the patch area and the deformation characteristics of the elastic body,provide theoretical guidance for the selection of the patch area and the selection of the sensor fixing method;By analyzing and comparing the offset of the lower seed rod in different layouts,it provides a data reference for the selection of the actual layout of the load cell.The growth equipment is divided into two working conditions,no-load and load,during operation.In order to obtain the motion characteristics of the upper transmission and weighing system in the actual operation process,it is necessary to conduct a modal analysis of its structure to obtain its corresponding modal parameters(natural frequency and modal shape),To avoid resonance in equipment operation and provide data reference for equipment failure analysis.A crystal growth model was established according to the characteristics of the Kyropoulos sapphire crystal growth process,and the model script was written using MATLAB software.Before the actual production of the crystal,it is necessary to design the crystal size in advance.By inputting the sapphire crystal-related size parameters into the script,the ideal growth curve for crystal growth is obtained,and the actual crystal growth process is guided.The simulation block diagrams of conventional PID control and fuzzy PID control are established respectively using Simulink simulation module in MATLAB software.Comparing the simulation results,it is found that the fuzzy PID control algorithm is slightly better than the conventional PID control algorithm in the stability,responsiveness and anti-interference ability of the system control,and the control effect is better,which provides theoretical guidance for the selection of the actual control algorithm.更多还原