The Investigation Of Counter-Gravity Casting PLC Control Technology

Counter-gravity casting(CGC) technology is an ideal method of producing large-size high-quality parts .The pressurizing control system of the counter-gravity casting is the core of counter-gravity casting equipment, and also the key of obtaining qualified castings. Based on the research about the characteristics and methods of PLC control system in the CGC equipment, and combined with the project of the large and multifunction counter-gravity casting equipment, the paper presents the design of the electrical-pneumatic system, PLC system and the computer monitoring system.The pressurizing pattern of counter-gravity casting is analyzed. The filling process and solidification process are defined in the view of control. Inlet parameters used to realize process control are determined. The effect of key parameters on the casting quality is analyzed, and several pressurizing patterns under different conditions are researched, which is the foundation of the realization of the filling process control of counter-gravity casting.The paper uses STEP7-Micro/WIN, provided with two kinds of programming languages, STL and LAD, to build the program for Siemens PLC S7-200. The program can finish data acquisition, data processing and control according to the technological requirement.In the master system design of CGCE, InTouch is used to build dynamic operation pictures with Windows style, such as parameter setting frame, process monitor frame, data processing frame, fault location and system animation, etc..According to the characteristics of different parts, the control loop of multifunctional CGC equipment is designed. And based on the control loop, this paper adopts PID+ Fuzzy controlling algorithm to implement the control system of CGC molten shaping process. Test results indicate that the system runs reliably with good tracing property, high accuracy and good usability.