Patent ID: 7854154

Claim:
A method of controlling a rolling process in which a metal strip is rolled flat by use of at least one roller, the method comprising the steps of: detecting the position of a neutral point in a contact arc between the metal strip and the roller; stabilizing the rolling process such that a position ξ of the neutral point is between a lower threshold value of 0.12 and an upper threshold value of 0.40 by intervening in the rolling process by use of suitable measures; calculating the value of the flat yield stress k e of the metal strip and the value of the hydrostatic pressure p N H at the neutral point as not directly measurable process parameters based on the calculated values for the flat yield stress k e and the hydrostatic pressure p N H on the basis of a first group of measurable process parameters and on the basis of the flat modulus of elasticity E* of the metal strip and of the compressibility K of the metal strip; calculating the position ξ of the neutral point according to the following formula: ξ = ( f slip + 1 ) ⁢ ( 1 - σ A 3 ⁢ K - p N + q N 2 ⁢ K + k e - σ A E * ) - 1 h E / h A ⁡ ( 1 + k e - σ A E * ) - 1 where f slip : represents the advance; σ A : represents the strip outlet tension; K: represents the compressibility of the metal strip; p N : represents the pressure in the roller gap at the neutral point, perpendicular to the metal strip; q N : represents the pressure in the roller gap at the neutral point, in the longitudinal direction of the metal strip; k e : represents the flat yield stress; E*: represents the flat modulus of elasticity of the metal strip; h E : represents the strip thickness at the inlet; and h A : represents the strip thickness at the outlet.