Based On The Sapphire Single Crystal Growth Cooling Water System Design And Implementation

With the development of technology, sapphire, as a kind of very important technical crystal, has been widely used in many fields such as phone’s screen and camera lens. Therefore, it is very impendent to increase the size and improve crystal quality of sapphire for the application. However, the growth temperature of sapphire will be a key factor of crystal quality, which depends heavily on the flow of cooling water. Then, it is very important to control a stable cooling water system for high crystal quality of sapphire.This paper aims to design the constant temperature and pressure cooling water system to solve this problem after reading and analyzing related literature. The following are the main research procedure:1. In order to achieve the constant temperature, we put forward a method which combines PID with PLC to achieve automatic control. The controller output based on PID was calculated according to the difference between the set temperature of system and the actual monitoring temperature. The electric two-way valve opening degree was automatically adjusted by the PLC program. In that case, the amount of water could also be automatically adjusted in the cooling tower to achieve the set temperature.2. In order to achieve the constant pressure, we put forward a method which combines PID with PLC to achieve automatic control. The controller output based on PID was calculated according to the difference between the set pressure of system and the actual monitoring pressure. The frequency of inverter was automatically adjusted by the PLC program. In that case, the pressure could also be automatically adjusted in the pump to achieve the set pressure.3. In order to make the cooling water system serve the production of sapphire, an applicable touch screen which displays the running status of the cooling water is developed. The window of the cooling water system was designed by drawing tools of touch screen software. The user could set the variable parameter by the screen, which made it easier to operate the cooling water system.