A new sensor for the evaluation of contact stress by inverse analysis during steel strip rolling

Knowledge of the contact stress between roll and strip becomes a critical factor in modern, high-speed rolling mills. In this paper, an inverse analytical method is developed to determine the contact stress in the roll gap by measuring the stress tensor with fibre optics at only one point inside the roll. Unlike many inverse methods, no matrix inversion is needed because the very small contact length would lead to ill-conditioned matrices. Iterative methods are also not studied because short computation times are desired. This approach uses the theory of elasticity on the assumption that the problem is isothermal and planar and relies on the expansion of holomorphic functions into a power series. On the other hand, the computation time is studied to rapidly optimise the industrial parameters during the rolling process. Hot, cold and temper-rolling simulations are given to demonstrate the accuracy of the method and the feasibility of this new kind of sensor, taking into account the restrictions (e.g., frequency of acquisition) of the local measurement system.