Silicon steel has strict requirements on the horizontal difference between the same plate. To reduce the transverse difference between the same plate of cold-rolled strip steel, it is necessary to ensure that the convexity and wedge shape of the hot-rolled silicon steel are minimized. The hot-rolled conventionally adopts 7 stands of CVC roll type rolling of silicon steel. However, the high requirements of silicon steel on crown and wedge shape and the characteristics of CVC machine lead to many defects in CVC roll rolling of silicon steel, so the large concave roll rolling technology of silicon steel is applied.
Large concave roll technology includes a roll shape design and a free roll shifting system. The practice has shown that the use of large concave roll technology can not only ensure the target convexity of silicon steel but also expand the rolling plan of silicon steel and improve the edge drop of hot rolling of silicon steel in the later stage of rolling. This technology It provides guidance for the integrated control of crown and wedge in hot rolling.
With the continuous improvement of industrial technology, the downstream users of silicon steel products have increasingly stringent requirements on the horizontal difference between the same plate. By comparing the information of cold and hot coils, it is found that the convexity and wedge-shaped assembly of hot-rolled strips lead to serious edge thinning of cold-rolled finished products. In practice, it is found that the reduction of the hot-rolled incoming material crown can effectively reduce the same-slab difference of the cold-rolled finished product, and the central crown of the cold-rolled strip is mainly affected by the hot-rolled incoming material crown.
By investigating the roll wear and measuring the cross-sectional shape of the hot rolling before and after the whole rolling, it is concluded that the key to controlling the lateral thickness difference of cold-rolled non-oriented silicon steel sheet is hot rolling, and the reason for the large lateral thickness difference of non-oriented silicon steel sheet is the hot rolling work. Roll wear causes excessive strip edge thinning.
Roll profile control technology for hot-rolled silicon steel must ensure rolling stability. Compared with conventional cold-rolled substrates, silicon steel has a larger rolling force, a smaller range of specification changes in a single rolling unit, and severe wear and tear on the “box shape” of the rolls in the later stage of rolling. However, the hot-rolled cross-sectional shape of silicon steel products requires high requirements. The target crown of the inner strip is stable, and it is also necessary to control the thinning of the strip edge.
In conclusion
(1) The use of large concave rolls and equal step length non-attenuating periodic roll shifting can effectively improve the wear of the work rolls and make the work rolls wear evenly.
(2) For the case that the number of coils rolled by a silicon steel unit does not exceed 70 coils, equal step length without attenuation of roll shifting is more conducive to improving the edge thinning of the strip steel in the later stage of rolling for the work rolls, and the crown control effect of the silicon steel is better.
(3) The large concave roll type is suitable for silicon steel rolling. It can realize free roll shifting rolling while ensuring the silicon steel target convexity, and it will not stabilize the rolling under the premise of improving the thinning of the silicon steel edge in the later stage of rolling. The properties and the strip steel have adverse effects on the neutralization wedge.
