Development Of ACE-Based Level2System For Plate Mill

In recent years, the successful introduction of plate production line from abroad promotes the development of domestic plate production technology. But unfortunately, the technology which was introduced is not digested and mastered completely, especially the black-box of process control system of mill. So that it is very difficult to improve the process technology or upgrade the control system. In addition, the rolling automation level and control precision such as plate shape and thickness in most of the domestic plate production line need to be improved urgently.This pater sets the development and application of process control system for plate mill as research object, and was supported by the open research fund "Development of L2System for Plate Mill" from the State Key Laboratory of Rolling Technology and Automation of Northeasten University. By researching on process control systerm design and founction realization, the ACE based level2system for plate mill was development, by learning from foreign advanced design idea and technology of process control system of plate mill. This system not only can be used in domestic plate production line, but also can provide support for decrypting the black-box. The main original works of this paper are present as follows:(1) Consulted the foreign and domestic system design of process control system, and considered the development trend of rolling automation, the multi-process architecture was adopted. The system is composed of15processes, which has single function and is relatively independent. In this way, the system stability can be improved, and any anomaly on anyone process can not cause system collapse. Moreover, multi-process architecture can also improve the flexibility of system. The system can be flexibly adjusted by adding/deleting process.(2) Through investigating the key technology thoroughly, such as communication middleware CORBA, ACE, TAO and OO4O, a new level2communication platform for plate mill was proposed, which based on ACE and OO4O. Using ACE_Malloc to creat a shared memory pool and all of the processes can realize communication by it. The communication between host computers can be realized by ACE Socket. Compared with traditional Socket, the ACE Socket has higher transmission efficiency and better stability. Using OO4O to access database is because that the access speed of OO4O is higher than common used ODBC.(3) According to the characteristics of single-stand/two-stand, different rolling strategys were developed. These rolling strategys can enhance the generality of schedule calculation model, so the schedule calculation model can suitable for different plate production line. Using the traditional method of schedule calculation usually cause flatness problem, when the plate mill has no hydraulic bending device. By analyzing this problem, last pass force lock-on method was developed and applied to schedule calculation. By using this method, the operators’ experience can be combined with schedule calculation models, and the operator can intervene to schedule calculation effectively. After this method was put into service, the shape problems decrease obviously.(4) Aiming at the disadvantage of unable to correct individual difference of plate of plate-to-plate adaptation, a new pass adaptation model is developed. This model uses the measured values of the last roll pass, such as measured roll force, roll speed and values of pyrometer etc, to calculate the current state of the plate, by recalculation of pass exit thickness module and short term correction of roll force module. Then use the recalculation of the remaining passes module to adjust the gap setup values of the remaining passes in the rolling schedule. Application of this model indicates that precision of roll force and exit thickness are improved greatly by this model.(5) There are two mill pacing control mode in mill pacing control process, including no-holding mode and holding mode. Aiming each mode, a simple and effective mill pace control method was developed. The batch mill pacing control method is used in holding mode. This method makes several slabs as a batch, and all of these slabs have the same initial dimension and target dimension. The slabs of a batch were discharged sequently, and holded behind the mill, when the before-holding rolling was completed. When all of the slabs complete the before-holding rolling, they will be transport to the holding zone before the mill, and starting the after-holding rolling. The batch mill pacing control method is much simpler and more useful than traditional cross rolling method.