Kunming Iron And Steel Bar Production Line Slit Rolling Process Optimization Studies

With the vigorous development of our national economy, the demand of diminutive profiled steel products increases progressively, the quality required become higher and higher. However, many of diminutive profiled steel plants exist some problems such as high-cost products' output is low and the energy consuming is high in our country. So adopting the advanced producing technique to increase the output and reduce the energy consuming are the mainly problems in steel field which need be resolved urgently on the current conditions. The slit rolling technology is a new rolling technology which is introduced and developed. This technique has many advantages such as the higher productivity, the less energy consuming and the lower cost. A lot of plants have applied the technique to the bar and the wire steel producing line, but there are many problems that the products' quality is not steady and the slit breed is single and so on. Lucubrate on the slit rolling theories, design and optimize the technique of new products are provided with the important practicality significance. The paper studied on the problems which were appeared in application of the slit rolling technology for the bar producing line of Kunming Iron&Steel Co.Ltd. in Yunnan province. Worked out the slit rolling technique of f18mm and f 20mm ribbed bar which is the bigger specification.The author discussed the slit rolling principle. Then the metal flow rule of rolling piece was also analyzed. The result indicated that the plate spread of rolling piece which in pre-slitting pass firstly extended by force, secondly contracted appreciably, finally extended by force too, then permeated in the whole pass, but in slitting pass, the plate spread with press submitted the linearity relation, and it extended by force from beginning to end.For studying the variety of influence factors in the slit rolling process, the heat/mechanics simulation experiment on Gleeble-3500 experimentalrolling machines was finished by author, the deformation resistance and strain-stress curve were tested, and the metallographic organizing configuration was also tested. The mutual influence laws of the three factors which were the deformation temperature and deformation degree and deformation rate were analyzed through the experimental data, and then the deformation resistance and regenerative coefficient were deduced. Suitable rolling power model and rolling moment were chosen, the temperature model was also established, after modifying and optimizing the real data of local plants, the models which mentioned above were all relatively accurate, therefore, mill load was calculated in rolling process. According to the relation of rolling temperature and deformation resistance, we can obtain the results that deformation resistance will up to 1.1～1.2 times when the rolling temperature drop down 50℃, the initial rolling temperature can drop down 50℃ when slit rolling the ribbed bar which less than f 18mm in the current bar rolling producing line of Kunming Iron&Steel Co. Ltd. The metallographic experiment indicated that the crystal of rolling piece could be thinned by dropping down the rolling temperature; consequently the mechanical performance of steel products was also improved.Based on the several models in slit rolling process, the author has designed and optimized the slit rolling pass system of f 18mm and f 20mm ribbed bar which was the bigger specification, and constituted the slit rolling regulations of f 18mm by reduplicate calculating. A rolling test on f 18mm ribbed bar had been worked, the first test has achieved success, a detailed analysis for slit guide unit after the rolling test had been done, and some corresponding measures were applied for that. By analyzing the data of the next several mouths, we found that the slit rolling state was stable, the output increase 50%～100%, the products' quality index became more advanced; the energy consuming and the cost became less comparing with the mongline rolling, the economy benefit was remarkable.In a word, slit rolling technology is a new rolling technique which canmarkedly increase the output and economize energy, although it has beenapplied widely, still has a lot of problems to be profoundly researched forus.