Research On Control System Of Large Size EFG Sapphire Crystal Growth Equipment

With excellent physical and chemical properties,sapphire crystals are widely used in military,industrial,and electronic equipment fields.Among them,large-sized sapphire crystals are often used as substrates for the windows of armored vehicles.The crystal growth furnace,as a crystal preparation equipment,has a very important influence on the quality of sapphire crystals.In this paper,we focus on improving the automation of crystal growth equipment from the point of view of isometry control.First of all,after a comprehensive analysis and mastering the working principle and process characteristics of various conventional sapphire crystal growth,this paper selects the EFG(edgelimited thin-film feeding and pulling growth technology)method for growing large-size sapphire crystals as the focus,and studies the isometric control strategy based on the law of energy conservation of crystal growth and the principle of crystal growth isometric control.The LJ-B85 single crystal furnace is used as the object,and the main components of it,such as the lifting motion device,motion control system,upper weighing and temperature control system,are focused on the study.From the EFG process,the crystal growth pulling motion device is designed to meet the requirements of Isometric growth,and the pulling motion control system is designed and studied.According to the functional requirements of the pulling motion,Taiwan Yonghong PLC is used as the motor controller,combined with servo motor and servo driver,and reasonable program design to ensure the accuracy of the pulling motion.Based on the actual growth rate of sapphire crystal compared with the theoretical growth rate and the difference of the two values to regulate the temperature,we designed the hardware platform for the up-weighing system and temperature control system,wired the equipment with a reasonable wiring method,and used C#.net for up-weighing according to the standard communication protocol of weight transmitter and programming requirements.software design.Finally,the software test platform was built to simulate the actual process of sapphire crystal growth using water droplets,obtain experimental data,plot theoretical crystal growth rate curves,and compare the experimental results with them to verify the reliability of the up-weighing software and the feasibility of the isometry control method.