| In recent years,with the progress of science and technology,a large number of electronic hand-held devices influx the market,the application of artificial crystals in electronic product equipment has received widespread attention.Synthetic sapphire crystal is currently in the LED industry,smart phones,watches,camera lenses and other products in large use,the future market demand is relatively large,the application prospects are more extensive.Therefore,the market demand for sapphire crystal quality is relatively high,the current quality of artificial sapphire crystal on the market uneven,from the production process to analyze the factors that affect the sapphire crystal quality,of which long crystal furnace cooling water system is one of the important factors,Constant water temperature is an important guarantee for high quality crystals.This thesis mainly aims at the problems such as inaccurate temperature control,low degree of automation,lack of emergency automatic protection device and so on existing in the 60 kg sapphire crystal furnace cooling water system of the bubble generation method in the current market.After the requirements of the water temperature for the bubble generation sapphire crystal growth process After the analysis,a set of automatic control system of cooling water for sapphire single crystals grown by bubble generation method was designed.Through continuous debugging and improvement in actual application,the temperature control of cooling water system was finally achieved in the entire crystal growth stage.Constant pressure and automatic operation of the operation,making the water temperature through the crystal growth furnace sapphire crystal growth process to achieve the required set temperature 25 ± 0.1 ℃.The main contents of this paper include the following parts:(1)In order to achieve the entire cooling water system of constant temperature and pressure control,the PLC controller as the core design of a set of automated system devices.Through the analysis of the mathematical model of the temperature of the heat in the process of the single crystal furnace,the simulation effect of the water temperature is analyzed by the conventional PID and the fuzzy PID control scheme.According to the site technology to collect feedback data and system settings parameters and other data,combined with PLC programming algorithm to achieve automatic adjustment of the scene of the electric control valve and inverter unit.According to process design structure automatically run two-stage circulation system,so thatthrough the crystal furnace inlet temperature reaches the sapphire crystal growth process set the desired temperature.(2)Based on the analysis of the cooling water system of the whole 60 kg sapphire crystal furnace,a stable and reliable two-stage circulating water control system is proposed.According to the calculation and selection of the required parameters of the system process Required PLC hardware and frequency conversion refrigeration unit hardware equipment.(3)In order to make the whole control system better serve the production of sapphire crystal,this paper uses the C / C ++ language to develop the PC operating software based on Windows platform in VisualStudio MFC development environment.According to the requirements of the site craft more reasonable and simple design of the entire cooling water system interface.Based on the theoretical foundation of the traditional cooling tower and PLC controller,according to the special requirements of water temperature for the growth of sapphire single crystal furnace,the technical composition of the cooling water system,the overall design of hardware and software and the content of performance index are designed.The set of automatic control system for cooling water with PLC controller as its centralized control system has some practical value in the automatic control of cooling water during the process of sapphire crystal growth through the verification of its effect in practical application. |
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