Research On The Motion Control System Of Crystal Growth By Cz Method

As a commonly used crystal material,sapphire crystal has excellent physical and chemical properties,so it is widely used in optical,engineering,military,medical and other fields.With the development of industrial technology and technology,the quality and performance requirements for sapphire crystals are getting higher and higher,which in turn requires better crystal growth equipment and more stable and accurate crystal growth control systems.This paper analyzes in detail the preparation process and respective characteristics of sapphire crystals common at home and abroad,uses the CZ method to prepare sapphire crystals as the research object,according to the process characteristics and requirements of crystal growth,first of all,the mechanical part is designed in detail,and the mechanical motion system is added to the lower transmission part(crucible rise and rotation)on the basis of maintaining the original upper transmission(seed crystal lifting and rotating);The following movement of the crucible relative to the seed rod was designed,and the proportional relationship between the crystal rise and the rate between the crystal rise was determined by calculating the follow-up ratio,which effectively solved the temperature field change caused by the decline of the solid-liquid interface in the crucible during the crystal growth process,thereby reducing the defect problem during the crystal growth process.The design adopts high-precision transmission equipment to ensure that crystal growth at ultra-low speed can also be in a stable running state,without crawling,jitter and other phenomena.After realizing the construction of the mechanical system,the control system is designed,the control system adopts semi-closed-loop control of position and speed feedback,takes PLC as the control core,and constructs the control system of "man-machine monitoring system-PLCservo drive",which realizes the four-axis motion control of CZ method growing crystals;In this paper,PLC is used to control the pulse output in a wide range and accurately,and the switch between low-speed and high-speed motion in the crystal ascending and rising motion is realized.Software compilation of the control system,using high-speed pulse output to achieve fast and accurate control of the motion control system.Design a monitoring system that can realize human-computer interaction,and realize realtime data transmission and control through the established communication connection.The design adopts two monitoring modes,on-site and remote,the human-computer interactive touch screen monitors the on-site crystal growth in real time,and the Modbus communication is established through the configuration king on the PC side to achieve remote monitoring and partial control.An experimental platform was built based on the LJ-J50 crystal furnace frame,and experiments were carried out after verification of each part of the motion control system.Observe the operating results of the human-computer interaction touch screen,export the data to the PC for further data analysis and processing,and prove that the CZ crystal growth motion control system designed and built in this paper has high precision and good stability through the comparison of actual operating value and theoretical value,which meets the requirements of fouraxis motion control in actual production.