Four Station Vacuum Forming Machine Control System Design And Development

In the production-line of refrigerator, vacuum-forming machine plays an important part and is used to produce inner case. The main function of control system is to heat the sheet to a proper temperature before shaped, meanwhile, sequential logic control is demanded. Vacuum-forming machine with four service positions introduced by Kelong company from Japan 1993 is a complete equipment composed of mechanical, oil pressure, pneumatic, electrical and control system. At that time, the control system belongs to advanced technology in the world. The efficient machine contributed a lot to the prosperity of Kelong. However, with the fast development of large-scale and very large-scale integrated circuit technology, the speed of PLC gets faster and faster. Industrial computer with higher performance is widely used.system failed to work because of bad modules. As to the HMI program, rough interface and not support mouse bring a lot of inconvenience to the operator to operate the system. Both hardware and software need to be upgraded. The hardware of original control system is behind the times. OMRON stops to supply modules of C2000H PLC and 386 industrial computer. Maintenance problem appears and is hard to be handled. In the end, the whole system failed to work because of bad modules. Setting out from actual problem, we keep the advanced parts of the vacuum-forming machine, like the servo system. We upgrade the control system.1, Understood the mechanism of the vacuum-forming system, the control methods of the pneumatic equipment, the fluid equipment and the electrical equipment. Has communicated with the technical personnel and known the function request and the interrelation of the stations, to make the whole control plan.2 , Has compartmentalized and optimized the control plan, analyzed the characteristic of each controlled object, known the scheduling logic request of the different movements. Selected the PLC module on this foundation, and chose the Kingview as the HMI software. The sheet carrying machine reserved the original servo control system, researched it and integrated it into the new control system. 3, The temperature detection and control is the key point and the difficulty of the control system. After summarized the open-loop control, the PID control which were often used domestically, studied the controlled object thoroughly, has decided to use the cascade control. And communicated with the experienced operators, has introduced their experience into the heating control of the sheet.4, Has carried on connection layout and construction, PLC programming, servo system programming, HMI program development, commissioning, unceasingly consummated the control performance, until the system can run normally and stably.The control system of vacuum-forming meets the productive demand. The original mechanical device and electric equipment are kept which saves a lot money for the company. High control performance and friendly HMI gain good comment of the operators.