Papers by Author: Zhen Hua Bai

Abstract: The setting goals of process lubrication were not all-inclusive in the previous manufacturer of double cold reduction. Strip shape, surface quality, the fuel consumption of unit and rolling stability could not be considered comprehensively. Aimed at the equipment and production craft characters of double cold reduction unit, at the basis of putting forward the comprehensive control index of a strip-shaped fuel consumption cleanliness for the first time, ensuring the shape quality of strip, lowering the oil residue on strip surface, improving the cleanliness of strip surface and reducing fuel consumption were defined as control targets; besides, the control of slip and heat-scratches were defined as constraints. A complete comprehensive optimization technology of process lubrication regime was established and has been applied to a 1220 double cold reduction unit belonging to Baosteel in China. Rolling speed, surface quality and strip shape quality are improved effectively, and oil consumption is reduced, meanwhile, the productivity and rolling yield of unit are ensured. This technology has created economic benefits for domestic steel makers and has further extended application value.

Abstract: A set of new mathematical models have been developed to calculate the temper rolling force of 2050 strip temper rolling mill. Based on the fact of small plastic deformation and elastic deformation occurring on the entry and exit of the deformation zone, new stress boundary conditions are described. The inhomogeneous distribution of internal stress in thickness direction is taken into account in the models, instead of uniform internal stress and assumption of plane strain traditionally. The new mathematical models have been applied into the temper rolling of 2050 hot rolling mills with good results. Comparison of calculated values and testing values for nine typical products has been given. The result shows that the calculated value of rolling force of temper mill is accurate.

Abstract: During the cold rolling of thin strip on the 1220mm five-stand tandem cold mills, scratch marks occur on the surfaces of strip and work roll. The surface quality of strip is degraded and the roll wear increases, which resulting in significant economic loss. In this paper, the mechanics of strip scratch marks was studied by carrying out both field experiments and theoretical analysis. Slippage Factor (SF) and Scratch Mark Factor (SMF) were presented to indicate the conditions of strip scratch marks. Meanwhile, mathematical models and simulation code were developed to optimise the rolling schedules and to improve the scratch marks. The practical application of the developed models to the 1220 mm five-stand tandem cold mills verifies the effectiveness of the developed models. The mathematical models can be applied to other similar tandem cold mills.