| The hot-pressing is one of the most crucial process in product line of wood-based panel, the work capacity of hot press determines production capacity of product line of wood-based panel, and its technical performance determine quality of wood-based panel. But the continuous press is not a single pressure equipment, it is electromechanical hot pressing equipments with high intensive, referred to wood-based materials, mechanism, micro-electronics, computer, micro-electronics, micro-electronics, instruments, etc. more and higher request were proposed pointing to control system, include more accurate detection and monitoring of speed, pressure, temperature, thickness and strip deviation, the logic control and interlock control for coordination of moving parts in subsystem, and the request that communication, analysis, display, handle, and manage of real-time data, also timely diagnose and deal with failures during processing.The high automatization and intellectuality of control system had been realised for continuous presses abroad, which play a important role in increasing of production,saving of materials,high efficiency,high quality and Energy Saving.The network communication of whole control system was mainly researched,and temperature control system with microcontrollers was developed, based on the mastery of network information technology and data communication, data processing and anti-jamming ability of host PC and microcontrollers, according to the status and development of product line for wood-based panel in china.The continuous press distributed control system was built based on RS-485 Bus by combining the design of control system with both hot-pressing processing and work principle, according to the characteristic of continuous hot press, which included enormous body, vast amount of data, long transmission distance, and complicated control.The data communication between master-control in central monitoring layer and five sub-systems in local monitoring layer was finished by using RS-485 Bus. The visual display and centralized monitoring of large data was achieved though utilizing the human-machine interface of big touches screen.The storage, deal with, and manage of data were completed, which made both control and management were real-time, the data management and data communication also were solated in a certain extent. The system could communicated with other equipments in Intranet and remote user in internet, and shared in certain data and message.The storage, analysis and supervision of data were carried out by using databank technology, which resulted to the field control,production, and data managements all with real-time capability, also made the data management and data communication to be disconnected to a certain degree.The temperature control system was designed based on the feature of independent heating for each of four areas in system, by using MCU. The aim, that heat system would automatically and safely run, when operator set several process parameter on human-machine interfaces of each four temperature control units, and real-time monitoring control, display, alarm was completed. Meanwhile, the real-time data was transmitted to master-control for other purpose. It concluded mainly three parts in the system designed.The temperature control agile algorithm of system was designed though find the relationship among hot-pressing boards thermal error, inlet oil temperature, feed temperature and aperture of the adjusting valve, based on the principle of heating-processing. The second heating circuit entered temperature stabilization status quickly and start to the normal production. The results of the operation showed that, temperature error was less than ±1℃, the accurate temperature control was realized, and made the system with certain agility, stability, and reliability. Lastly, the shortening of heating time played a critical role on efficient and energy saving of production.The rational and effective distribution of multitask by using modular design method of colony controllers and their circuit. The problems of anti-interference were solved in system. And certain redundant was reserved for system expansion.The real-time and multitask control of microcontroller system was achieved by using time-sharing technology and modules of hierarchical method in software designed, with rational hierarchy structure of software, module partition and task scheduling, according to the characteristic of temperature control system. In addition, the stability of system was assured.The combination of software and hardware in temperature control system made the expansion and reconfiguration of system was easy to realizing. And the temperature control system had main characteristic of intelligent system, based on the implement of each temperature control unit on autonomy, initiative, reactivity and interactive. The intelligence of whole continuous press distributed control system would achieve in next step, if putting this method on other subsystem.The hydraulic pressure and other control subsystem could be built and achieved related function swiftly in this system network architecture by using the designed method of temperature control system, and to completing the continuous press control system. |
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