| Due to the increasing demand for high-quality and high-performance steel in the market,it is difficult for the high-performance cold-rolled sheet produced in the market to meet the market demand.Therefore steel enterprises and related research institutions urgently need a continuous annealing simulator for the development of cold-rolled products.Compared with the production line,the continuous annealing simulator can not only control and regulate the heating temperature,time,etc.,the experimental process flexibility and operability is strong,but also can effectively reduce the research cost and improve the research effect.The temperature control accuracy of the specimen is one of the core indexes of the continuous annealing simulator,with the continuous annealing simulator developed by the state Key laboratory of Rolling and Automation in Northeastern University as the background,and the single-piece small sample as the research object,developed the rapid heating control feed-forward model,and formed the rapid heat treatment experimental technology.Based on the characteristics of the typical cold-rolled strip steel continuous annealing production process,the design of the scheme structure for the rapid heat treatment experimental system for the single sheet thin strip steel specimen is completed on the continuous annealing simulator,according to the resistance rapid heating method and the basic theory of metal heat transfer.The dynamic calculation of the fast heating process and temperature control process stability of the belt steel resistance is focused on,and optimizes the model parameters through a large number of experimental data,and obtains better application results.The details are as follows:(1)The specimen is heated by resistive heating on the continuous annealing simulator,and the temperature control is achieved by controlling the angle of the silicon controlled rectifier,and then controlling the original side voltage of the heating transformer and adjusting the current of the circulation specimen.According to the principle of rapid heating of resistance,a heating feed-forward control mathematical model was established to obtain the changing relationship between the sample relative resistance R1,cable relative resistance R0,sample size,heating rate and feed forward control quantity.(2)The mathematical model of heating feed-forward control is applied to the continuous annealing simulator,and the parameter optimization adjustment is obtained in the course of practical application,and the control accuracy is obtained:The temperature at the heating stage can be controlled within ±5?,the temperature at the inflection point can be controlled within±8 ?,and the temperature at the insulation stage can be controlled within±3?;The measured temperature difference of four thermocouples is less than 5?,and the temperature uniformity is good.(3)By comparing the conventional PID heating method with the combined heating method with feed-forward model,it is found that the combined heating method with feed-forward model has the function of early prediction,and avoiding the temperature curve can not keep up or overshoot at the inflection point of the temperature curve;it has obvious advantages in adapting to a wide range of sample width,thickness variation and heating rate change,stable control system,small temperature fluctuation and good stability.(4)A variety of cold-rolled strip steel sample heating experiments were carried out on the continuous annealing simulator,a large amount of test data were collected,and determine the average heat zone for the sample temperature,and the grain size and hardness test of the metallographic test observation organization in the uniform distribution location of the average temperature of the typical sample temperature were tested,and the results showed that the average grain size of more than 80%was concentrated in 2?m-5?m.The average hardness value is relatively close,and the organization and hardness uniformity are good. |
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