Analysis of the Thermal-force Roll Profile Control Ability Under Different Hole Structures and Slot Structures in the RPECT

Roll profile electromagnetic control technology (RPECT) is a strip flatness control technology based on the flexible control of roll profiles. As the core component, electromagnetic sticks can bulge with the induction heating of induction coils. To ensure the integrity of the coil circuit, the surfaces of the electromagnetic sticks need to be provided with slots. Moreover, the inner hole of the electromagnetic control roll is also needed to install the electromagnetic stick in the roll. The structures of the inner hole and slots affect the local structure of the electromagnetic stick and the electromagnetic control roll and then change the roll profile control ability. To research the radial bulging ability, the roundness of bulging, and the composition between the thermal crown and force crown under different holes or slots, a finite element model of circumferential RPECT is established by using the finite element software MARC. After analysis, the results showed that the radial bulging ability and the roundness under the influence of the roll radius were larger than those under the influences of the slot radius and slot amount, and the composition characteristics of the comprehensive roll profile were different under different conditions. Therefore, to achieve accurate roll profile control, the influences of the structures of holes and slots need to be included in the RPECT index.

Multi-Objective Optimization of the Hot Rolling Scheduling of Steel Using a Genetic Algorithm

ABSTRACTThe hot rolling process reduces a slab passing through a series of work-rolls to obtain a strip of target thickness. Developing robust, efficient, and accurate simulation methods improve the process. This research aims to minimize the hot rolling time, bending of work rolls, thermal crown, and wear of work rolls, subject to some process constraints. The problem solution is by using a multi-objective genetic algorithm with four function objectives. The second generation of the Non-dominated Sorting Genetic Algorithm was chosen to solve the problem of this research. A probed constitutive model has been incorporated into the algorithm to compute the flow stress as a function of the chemical composition of steels. The algorithm implemented to minimize the four objectives proposed obtained the optimal schedule and associated makespan.

Calculation and Analysis of Tandem Cold Rolling Force Parameters

In order to improve the accuracy of rolling force parameters,the elastic deformation and pressure between rolls of tandem cold rolling are calculated using divided element method in this paper. Bland-Ford model is used to calculate the rolling force, and the lengths of flattening contact arcs of each element are calculated. Considering the flattening contact arc lengths and tensile stress synthetically, rolling force parameters are calculated iteratively. Then the corresponding procedure is developed, and the distribution of rolling force, pressure between rolls and tensile stress are calculated with this procedure. The results are basically consistent with the measured data, and it will be useful to thermal crown calculation and strip flatness control.

Calculation Model for Thermal Crown of Work Roll in Hot Strip Rolling

The finite difference method model of temperature field and thermal crown of work roll on hot strip mill was researched. The temperature field and thermal crown were calculated, surface temperature distribution and thermal deformation were both reduced from center to edge. The computed and measured roll surface temperature were comparatively in good agreement with each other, practical application results show that the model has high calculating speed, high precision and can meet the needs of the strip shape on-line process control.

Thermal Crown Analysis of the Roll Sleeve in Twin-Roll Strip Casting Process

In the twin-roll strip casting process, analyses of heat transfer and deformation for the casting roll sleeve are carried out by using the finite element program ANSYS to examine the the thermal crown. The effects of several factors such as molten pool temperature, heat flux onto the roll surface and roll edge, heat flux onto the cooling channels, and cooling water temperature on thermal crown are investigated. The results show that the thermal crown does not change sharply during the casting process, after the casting roll reaches thermal equilibrium.