Control Models And Simulation Research On The Hydraulic AGC System Of Cold Rolling Mill

The high precision rolling technology has put forward the higher requirement for the control accuracy to the hydraulic AGC(automatic gauge control) system of cold rolling mill. Therefore, in order to analyze the influence to the control accuracy of various factors in the control system as well as select control strategy reasonably, the simulation study on the hydraulic AGC system of cold rolling mill possesses the practical meaning. This thesis carries on the comparatively deep research into the hydraulic AGC system of the first stand in WSPC's 1700mm 5-stand tandem cold mill.1. The basic theory of automatic thickness control of cold rolling has firstly been discussed in the thesis. In combination with the research object of this subject, the thesis concretely analyzes the related control strategy, control principle and the basic algorithm of this AGC's system.2. According to the concrete hydraulic APC(automatic position control) system, the nonlinearity and asymmetry of servo-valve load flow, the elasticity deformations of various parts and the mass distribution system of rolling mill load, as well as the complexity of plastic deformation for the cold rolling steel strip, have been studied synthetically. And the thesis presents the mathematical model of hydraulic APC system, which is comparatively complete and accords with the physical device system. At the same time the basic traditional AGC system and mass flow AGC system model are built respectively.3. Based on the building model, the author carries out the digital simulation with the real rolling data, and analyses the influence to the system response characteristics of important parametric variation in hydraulic APC system.4. With the contrast of the actual value and simulation value, the accuracy of building model has been verified, and then by way of analyzing the characteristics of various AGC control strategies by simulation, optimum technology scheme, control scheme as well as parameters of control system can be provided for the practical rolling on site presently.5. The simulation on the supply of AGC system indicates that the hydraulic power supply's pressure of the low frequency wave can create unfavorable influence to the thickness precision of steel strip. Regarding the stability of pressure in the power supply as the analytical aim, the thesis utilizes hydraulic simulation software EASY5 to carry on the simulation analysis for the hydraulic power supply of hydraulic AGC system. The analysis finds out the influence law to the pressure wave before the servo-valve of main parameters in the supply system. And for the practical system, the result can provide the reference basis for the correct parameter selection such as the volume and installation position of accumulators, etc.