Patent ID: 8243284

Claim:
A method for measuring the roundness or for measuring the shape deviation of round profiles moved forward in longitudinal direction inside of rolling mills, for which in a manner known per se and with the aid of a measuring instrument using two laser scanners, respectively provided with a light-sensitive sensor and a laser, at least three shadow edges that fit against the round profile to be measured and enclose the round profile so as to form a polygon are generated and measured and the corresponding tangents are computed from this, characterized in that a) prior to the measuring operation a center (Z 0 ) is calibrated and determined in the measuring field, provided such a center (Z 0 ) was not previously determined; b) perpendiculat lines (r 1 , r 2 , r 3 , r 4 , r 5 , r 6 , r 1′ , r 2′ , r 3′ , r 4′ , r 5′ , r 6′ ) are determined from the center (Z 0 ) to the tangents (T 1 , T 2 , T 3 , T 4 , T 5 , T 6 , T 1′ , T 2′ , T 3′ , T 4′ , T 5′ , T 6′ ) and the distance from the center (Z 0 ) to the tangents (T 1 -T 6′ ) is computed in this way; c) the corner points (A to K) of the polygon enclosing the round profile are computed, wherein a contour is determined; d) that a reference circle is positioned relative to the contour in such a way that i) the square shape deviation of the contour relative to this reference circle reaches a minimum; ii) the reference circle represents the smallest possible circle that can fit around the contour, iii) the reference circle represents the largest possible circle that can fit inside the contour; or iv) the reference circle together with a different circle, arranged concentric to the reference circle, encloses the contour with a minimum radial difference; e) the diameter (D ref ) of the reference circle is computed and determined from the position in space of the reference center (Z p ), which represents the center point of the reference circle, and f) at least two vectors extending from this reference center (Z p ) to the contour are computed and that the out-of-roundness is determined from the obtained data.