Reserch On Plate And Strip Rolling Process Control System And Key Models Of Rolling Force

Process automation control system is an important part of plate and strip rolling computer control system, and it is the most effective control method to ensure the product quality. Under the background of taking part in many new or renovation plate and strip production lines at home and abroad, taking plate and strip rolling process control system as the research object, system architecture and function realization are researched. Rolling process control system application platform and data acquisition and analysis system are designed and developed. Aiming at the characteristic of fully continuous and fast pacing for hot strip line, the whole process tracking is improved. The good practical effect and profit have got since the research results are successfully applied in the scene. Meanwhile, relying on Natural Science Foundation of China "study on the application of strain rate vector inner product method in the rolling power variation" (No.51074052), the key models of rolling force of the process control system are researched deeply. The main works and results are as follows:(1) The hardware and software were designed for the process control system application platform. Consulted the foreign and domestic system design of process control system, and considered the development of computer technology, the general-purpose PC server was used as the system hardware and Windows series software was taken as development tools. The multi-process, multi-thread and modularity framework-based software architecture was adopted, and function modules were interacted by event mechanism. The application result on site has proved that the system design has its own advantages. On the premise of guaranteeing the system stability, the system development is convenient, and system cost is low. In addition, the architecture of platform has strong versatility and adaptability, and can be flexibly applied various kinds of production line. The platform plays a positive role in promoting the fully automatic production of plate and strip line in our country.(2) The tracking function of process control system for fully continuous hot strip was improved. Taking the characteristics of fully continuous hot strip line into account, some key problems including rolling more than one strip at the same time et al. were proposed, meanwhile, the corresponding coping strategies were presented, including embedding material tracking function within the process control system, dividing the rolling area into several double-queue logical partitions, setting up a double storage area for each stand, combining every instrument signal on the line organically, limiting the maximum threading speed of later strip using "the minimum safety distance". The improved tracking function was successfully applied in the scene. Its stable performance has effectively improved the rolling pacing, and increased production capacity.(3) Data acquisition and analysis system of rolling process control was designed and developed. SIEMENS CP5613 A2 was used as the high speed data acquisition card, the general-purpose PC was adopted as data server, using PROFIBUS-DP to connect L1, data acquisition and analysis system was developed successfully, and with shortest sampling period was 4ms. The system has characteristics of low cost, high sampling rate, strong practicability and stable performance. It has practical significance for promoting the level of equipment of domestic small and medium-size enterprise.(4) The global weighted velocity field was simplified for analysis of plate{l/(2h)<1) and strip (l/(2h)> 1) in hot rolling. The strain rate vector inner product and co-line vector inner product, as well as integral mean value theorem were used respectively in plastic deformation power, friction losses and shear power. A theoretical solution of rolling force was obtained and calculated results by the solution were compared with those measured ones. It shows that the result has high calculation accuracy. However, taking account of double barrel for plate, parabolic distribution of vz along z is more reasonable than linear distribution, and the effect of elastic flattening of rolls on stress state coefficient in hot strip rolling is relatively small. In additon, the effects of various rolling conditions such as thickness reduction, friction factor and shape factor, upon separating force, location of neutral angle, and stress state coefficient were discussed systematically. The method has linearized Mises nonlinear functional power from the view of mathematical directly, and realized the operation of strain rate tension reducing to the vector inner product and summation.(5) A new kinematically admissible logarithmic velocity field was proposed. Using the velocity field and EA yield criterion, the finishing rolling force of hot strip line was firstly analyzed. Moreover, the effects of friction factor and geometry factor on the location of neutral point were also presented. It is found that the calculated results are consistent with measured ones. The above method is instructive for rolling power functional analyses.(6) An antisymmetric parabolic dog-bone shape function was firstly proposed for analysis of vertical rolling. Using the function, and dividing the bite zone particularly, a kinematically admissible velocity field was also derived for the kind of rolling and the total vertical rolling power obtained. With the field and angular bisector yield criterion the internal deformation power was successfully analyzed. At the same time, the friction losses and shear power were also worked out respectively through Pavlov projection principle. Then, by search method for minimizing the total power functional, the vertical’ rolling force was received. Meanwhile, the complete contour function expression of rolled piece after deformation can be obtained by this model. The results of the rolling force and shape profile were compared with those by Duckjoong’s model to verify its correctness. It shows that the new model has certain reference significance for width control and rolling force prediction of vertical rolling.