Research On The Weighing And Diameter Control System For Large Sapphire Crystal Growth

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.