The Optimization Design And Analysis About The Surface Pressure Pneumatic Servo System Of The Low Pressur Casting

The low pressure casting technology is an important special casting technology.Compared with the traditional casting technology, it has the advantage of high materialutilization and which is also easy to get clear outline of castings, etc. At present, theautomation of domestic low pressure casting equipment is not high, and the foreignequipments are too expensive to be afforded. These factors restrict the development of thefoundry industry, therefore, to speed up research and development of the low pressurecasting technology is very important.This research aims at solving the problems of the surface pressure control precisionof the low pressure casting in the actual production, have finished the improvements onthe original system, and add the appropriate control strategy. First of all, according to thecharacteristics of the low pressure casting process, this paper introduces the workingprinciple of the low pressure casting. With the intent to achieve ideal control effect whichthe surface pressure pneumatic system should do, design the closed-loop control ofpneumatic servo system. In order to ensure the safe operation of the system and preventthe system pressure is too high, three parallel pressure relief ways are proposed in thispaper, enhanced the reliability of the work.Secondly, the max air consumption which the pneumatic system need wascalculated,and on this basis to select the appropriate electrical servo valve,of course, thecalculation and design selection about the other critical element are finished at the sametime. Calculating the increase of the gas space velocity in the heat holding furnace duringthe max air is consumpted, which can lay a foundation for building the variable volumeelement model in the simulation software AMESim.Thirdly, aiming at the improved pneumatic servo system, this paper build thephysical modeling in the simulation software AMESim, adding the logic control signalsinstead of all kinds of converters in the actual production, And all the components’parameters are set up according to the actual situation.Then by the simulation, to verifywhether the improved surface pressure system is conform to the requirements of the low pressure casting process, is better than the original system control precision.Finally, aiming at the problems in the process of the low pressure casting, such as thepressure control is not very accurate, the pressure response lag and so on, building themathematical model of the whole system, and attempt to add to the PID control strategy toimprove the systems’ performance. Through the analysis of the interference factors suchas the temperature and changes in the gas space that can destroy the pressure controlprecision in the process of liquid surface pressure, determining the surface pressurepneumatic system is actually a time-varying nonlinear system, so this paper bring theco-simulation technology is present with AMESim and Matlab to solve the aboveproblems. Then, design the self-tuning fuzzy PID controller and use the software ofMATLAB/Simulink and AMESim to emulate, Finally, simulation results prove that theself-tuning fuzzy PID controller is very suitable for being used in surface pressurepneumatic servo system of the low pressure casting, The quickness and accuracy of thepressure have made great improve and the control effect is the best.