Analysis of strip edge cracks during cold rolling of thin strip

In this paper,the mechanics of strip edge cracks and its propagation has been studied,and the effects of strip edge drop and stress intensity factor(SIF) on edge crack defections during cold rolling of thin strip have been discussed.An experimental investigation was presented into the effect of strip edge drop on edge cracks during cold rolling of thin strip.The edge crack increases significantly due to more inhomogeneous deformation and work hardening at the strip edge.The effective stress intensity factor range is important as it represents the major physical cause of the crack propagation.The efficiency and reliability of the SIF analytical model has been demonstrated in the study.The proposed method for predicting strip edge crack is helpful in producing defect-free products and providing an understanding of the mechanics of edge crack propagation in cold rolling of thin strip.

Transverse thickness difference control technology for non-oriented silicon steel

Transverse thickness difference is an important quality index of non-oriented silicon steel strips. In order to fulfill users＇ accuracy requirements on the transverse thickness of silicon steel and improve the production yield, the factors influencing transverse thickness difference were analyzed. Then the work roll shape, control strategy and incoming hot-rolled strips were optimized. Since the optimization measures were implemented in the actual production, the thickness difference of non-oriented silicon steel has been reduced greatly and fulfilled the requirements placed by users. These measures have achieved remarkable effects.

A brief investigation on transversal temperature distribution during hot rolling

Temperature evolution of a working piece during hot rolling has a significant influence on the microstmcture and final mechanical properties of the material. As the measurement technologies improve, on-line measurement of the temperature across the strip width has become accessible, and thus monitoring and control of the transversal temperature distribution during hot rolling can be realized. The scanning of the temperature across the strip width can help us to understand the state of the temperature variation at the strip edges and as a result help us improve the temperature homogeneity of the strip. In this paper, reaearch on temperature distribution along the strip width is reviewed first, and then the mechanism of the scanning measuring devices is introduced. With the temperature scanning measurement data taken from the finishing mill entry point and the down coiler entry point, the temperature distribution at the strip edges is analyzed. It is pointed out that the roughing process is the main contributor to the temperature inhomogeneity. Furthermore,the contribution of the edger heater to the temperature homogeneity is investigated.

Rectangular Section Control Technology for Silicon Steel Rolling

Rectangular section control technology （RSCT） was introduced to achieve high-precision profile control during silicon steel rolling. The RSCT principle and method were designed, and the whole RSCT control strategy was developed. Specifically, RSCT included roll contour design, roiling technology optimization, and control strategy development, aiming at both hot strip mills （HSMs） and cold strip mills （CSMs）. Firstly, through the high-performance variable crown （HVC） work roll optimization design in the upper-stream stands and the limited shifting technology for schedule-free rolling in the downstream stands of HSMs, a hot strip with a stable crown and limited wedge, ：local spot, and single wave was obtained, which was suitable for cold rolling. Secondly, an approximately rectangular section was obtained by edge varying contact （EVC） work roll contour design, edge-drop setting control, and. closed loop control in the upper-stream, stands of CSMs. Moreover, complex-mode flatness control was realized by coordinating multiple shape-control methods in the downstream stands of CSMs. In addition, the RSCT approach was applied in several silicon-steel production plants, where an outsicanding performance and remarkable economic benefits were observed.