Brief introduction of reduction system for packaging steel strip hot rolling

Brief introduction of reduction system for packaging steel strip hot rolling
　　The rolling mill reduction system is the main actuator for thickness control. In the past, electric reduction was used, that is, the reduction motor was driven by a two-stage cylindrical gear and a first-stage worm gear to drive the screw to adjust the roll gap. The first generation Because the AGC function is not considered in hot tandem rolling, the power design of the reduction system is not only too small, but also the design of the screw pitch is too small, which greatly reduces the transmission efficiency and makes the static torque of the motor too large, which cannot meet the needs of AGC thickness adjustment. The acceleration cannot even carry out strip reduction. The second generation of hot strip rolling puts forward clear requirements on the performance of electric reduction and thickness adjustment, that is, the reduction system is required to have a reduction speed of 1.2-1.5mm/s and a reduction acceleration greater than 2mm/s2.
　　 For this reason, a low inertia reduction motor, double pressure operation, a larger screw pitch, a thrust bearing between the reduction screw and the bearing seat, etc. are adopted. However, electric pressure adjustment has the following congenital characteristics Disadvantages:
　　 (1) Frequent up and down adjustments can easily cause wear and tear on the drive mechanism;
　　 (2) The dynamic response is still not enough for high frequency interference;
　　 (3) When the rolling force is large, the slow motion will be significantly reduced.
　　 Therefore, in the transformation of existing rolling mills, the scheme of electric pressing + fine-tuning hydraulic cylinder is widely used. Save investment, generally only add hydraulic cylinders to the rear 3 or 4 racks.
　　 Since the response speed of the hydraulic cylinder is nearly 10 times faster than that of electric pressing, the thickness adjustment accuracy is greatly improved.
　　 With the development of hydraulic technology, all newly built hot strip mills since the mid-1980s have adopted full hydraulic pressing, that is, long-stroke hydraulic cylinders. This technology is used.