Research On Nitrogen Protection Control System For Reflux Sintering Plate

Reflow sintering is an important process,and the level of sintering directly affects the sintering quality of components.According to the development of the sintering process and the research of the existing technology,the sintering equipment often uses vacuum as the sintering atmosphere.The temperature control precision is high,but the structure is complicated,the volume is large,and the cost is high.A small-scale and cost-effective sintering scheme for small and medium-sized processing enterprises is proposed.The nitrogen gas protection control system of reflux sintering plate is designed.The nitrogen gas is used as the sintering atmosphere to protect the sintering process.The pre-feedback decoupling control strategy based on integral separation fuzzy PID improves the temperature control accuracy,which has important practical significance for the development of industrial sintering technology and the updating of sintering equipment.The focus of this paper is to study the sintering temperature control algorithm and complete the system software and hardware design and debugging.Firstly,it is determined that the sintering control system designed in this paper consists of three parts: computer,system console and sintering plate.According to the design requirements,a detailed design scheme is proposed and the device selection is completed.Then according to the selected device,design the hardware circuit based on STM32F407,including system power supply circuit,temperature acquisition and control circuit,nitrogen concentration acquisition and control circuit,draw schematic diagram with Altium Designer and design PCB to make hardware circuit board to realize sintering plate Control of temperature and nitrogen concentration.Secondly,considering the timeliness and complexity of the computer control system,the integral separation fuzzy PID control algorithm is designed to control the sintering temperature.The simulation is compared with PID,fuzzy PID and integral discrete fuzzy PID to verify the integral discrete fuzzy PID designed in this paper.The control strategy is superior to conventional PID control.At the same time,for the coupling effect of multivariable control system,the pre-feedback decoupling control strategy is designed.After MATLAB simulation comparison,it shows that the decoupled temperature and nitrogen concentration data are better than decoupling,and the decoupled temperature is not over-adjusted.The adjustment time has increased by 31%.Finally,the console software is written on the Keil5 platform to complete the algorithm migration.The human-computer interaction interface is designed by LabVIEW.The data is sent and received with the STM32 through the RS485 serial port.The temperature setting module,the automatic running module and the data query module are written according to the functional requirements.Designed and planed the front panel layout,so that the human-computer interaction interface is neat,beautiful,and focused,which is convenient for testers to use.In order to ensure the reliability of the system,the entire system is tested before being put into operation,including functional testing and accuracy testing.First step in the upper machine to complete the cycle test and automatic run test.The value detected by the detector with higher precision than the design requirement is taken as the standard value,and compared with the actual measured value,the temperature and nitrogen concentration data are analyzed in the form of a table,and the control precision of the system is verified to meet the design requirements.