| Complete equipment of large pickling and tandem cold mill is comprehensive technology possessing a strong systemic, great technical difficulty and high precision requirements in cold rolling production. And independent integration of core equipment and technology is one of the important goals about independent production of advanced metallurgical equipment. Based on building and automatic control system development project for 1450mm pickling and tandem cold mill, the study was carried out on rolling characteristics, hydraulic gap control, automatic gauge control, automatic tension control and mill master control and so on. The research results were applied to practical production, which had good performance. The main work is as follows:(1) The composition and parameter calculation method of deformation zone in tandem cold rolling process were analyzed. In order to simplify solving differential equations, solving the rolling process parameters by numerical integration method was studied. The rolling force model, deformation resistance model, friction coefficient model and forward slip model were given, and the basic equations for strip rolling process were studied including mass flow equation, mill spring equation, tension equation and power equation.(2) Taking basic equations for rolling process into account, the incremental models of the rolling process characteristics analysis were established. According to the law of derivation, partial differential coefficients of rolling force, rolling torque and forward slip were individually calculated. And the influence coefficients of rolling process parameters were calculated through the use of matrix operations. Collaborative optimization control of thickness and tension was studied, and the riccati equation method of linear quadratic optimal solution was given. The effect of thickness and tension from raw material thickness fluctuation was studied by simulation.(3) Depending on the product thickness accuracy requirements and special instrument configuration, a set of automatic gauge control system and automatic tension control system for strip cold rolling was designed and established. In order to eliminate the signal interference, a new method for designing the band filter based on the bilinear transformation was developed. Two control methods for hydraulic gap control system were studied. Control theory and algorithms of feed forward AGC, mass flow AGC and monitor AGC based on smith predictor were given. The indirect tension control strategy was designed to control tension for the mill entrance and export. In order to ensure stable export coiling tension, the setting method of taper tension was given. And normal tension control and safe tension control were developed for inter-stand tension control.(4) Taking tandem cold rolling characteristics and actual situation into account, a set of mill master control system for strip cold rolling was designed and established. The speed control technology was studied especially preset value processing, master speed calculation, strip tracking and strip tail positioning. Control algorithms and structures of flying shear and coiler were improved to achieve a stable automatic cutting and coiling. Combined with actual situation, countercurrent adjustment method was used to achieve flying gauge change.(5) The hardware network configuration and software architecture of automatic control system for tandem cold mill were given. Several key issues were elaborated about control system design. The control results of hydraulic gap control, automatic gauge control and automatic tension control were analyzed using actual curves. A convincible evaluation for the control system was made.The results of the study are practical for thickness control, tension control and mill master control of tandem cold mill. The automatic control system has been applied successfully in 5-stand tandem cold mill of a certain cold mill plant. It is benefit to the computer control level of tandem cold mill in China. |
PDF Full Text Request