Research On Control System Of Cooling Power For The Cubic Synthetic Diamond Press

The cubic synthetic diamond press is the main production equipment of synthetic diamond with static high-temperature and high-pressure technique. The stability and accuracy of pressure and temperature in a long time are the prerequisite for producing high grade diamond. The temperature control is crucial and become difficult of high grade diamond’s synthesis because of immeasurability. The temperature of synthesis depends on the heating conditions and cooling conditions.Heating conditions are controlled by heating system. Cooling conditions are associated with cooling water, environmental temperature, humidity, air flow, and the temperature of press body. The cooling water is the main way of heat dissipation. The workers adjust the flow of cooling water according to the different synthesis process,hammer temperature and quality after synthesis. The operation process is under human experience, which can not be quantified. It’s aimless, uncontrolled,inefficiency. Cooling conditions are controlled by aiming at the water’s cooling power,which realized quantitative and controlled cooling process. The system increased the controllable factors, creating favorable conditions for the high grade synthetic diamond.The water cooling system is designed. Six channels of water cooling power are calculated respectively by collecting inlet temperature, six outlet temperatures and six flow signals. The current cooling power is controlled by using PID algorithm and stepper motor. The indoor temperature has impact on thermal dissipation of cubic synthetic diamond press. Indoor temperature module is designed, aiming at wireless networking and low power. Variation of room temperature is compensated according to the compensation algorithm.In terms of hardware design, the cooling power control system of the whole circuit is completed, including power module with flyback converter, indoor temperature collection module, water temperature collection module, flow collection module, stepper motor driver interface and communication interface etc. Signalscollection, stepping motor driver and data transmission are realized. The system adopts photoelectric isolation technique to increase anti-jamming performance.In terms of software design, RS485, RS232 and wireless communication interface based on Modbus protocol are designed. Automatic calibration technology of circuit and high precision fitting method are used to get high precision of temperature measurement. Flow signals are measured in equal precision using the timer and external interruption. Six channels of stepper motor deceleration in S type curve is achieved by using iteration method, costing very little CPU time. Ascending curve method is used to obtain system model parameters, calculating PID parameters according to the Z- N method. It achieves a good control effect by combination of normal PID and multi mode PID.