Researches On Nitrogen Pressure Control Strategy In The Production Process Of Fine Aluminum Powder

With the innovative application of aluminum powder in laser or surface engineering, enterprises raise higher demands about tiny volume, high purity and spherical characteristic of aluminum powder. This trend requires a more effective control system of manufacturing. Based on the study of process principle and basic control requirements, this paper proposed a control strategy of nitrogen pressure during atomization and grading.Aiming at the nonlinear characteristic between valve open degree and nitrogen flow during atomization process, a compound controller called Fuzzy-PID is proposed. By means of switching operator to realize smooth transition between Fuzzy controller and PID controller, this method not only keeps transient advantage of Fuzzy algorithm, but also achieves steady advantage of PID algorithm. The application in production site verified that the compound controller can eliminate the limitation of either controller in nonlinear system and achieve satisfactory results.Aiming at the long-time fluctuation of grader caused by pressure disturbance from cyclone cluster, feeder and balance tank during grading procedure, a cascade control strategy with Smith predictor is proposed, which takes grader pressure as main parameter and takes balance tank pressure as auxiliary parameter. Above-mentioned methods achieve a better response speed and regulating time, moreover, it improves the anti-jamming ability and the efficiency of classification system.Siemens redundancy PLC is chosen as core controller to work with IPC and manufacturing machine in process control network. STEP7and WinCC are chosen as software development platform to design PC interface which can realize start or stop operation, parameter configuration, etc. The control system can achieve precise and real-time regulation of production process, and improve the economic efficiency of enterprise.