Method for determining the thickness of a material strip during the feed of the material strip to the machining zone of a machine tool

A method for determining the thickness of a material strip when feeding the material strip to the processing area of a machine tool comprising the steps:

• a) Providing a roller arrangement with two rotatable rollers, the two rotatable rollers including a first roller and a second roller, wherein axes of rotation of the two rollers are parallel and the rollers are movable perpendicular to their axes of rotation relative to one another;
• b) Positioning the rollers relative to each other such that the two rollers are in contact with each other, and detecting in this state a relative position of the rollers to each other as a reference relative position;
• c) Arranging a material strip between the rollers such that the longitudinal direction of the material strip runs perpendicular to the axes of rotation of the rollers and the material strip is clamped between the rollers;
• d) Advancing the material strip clamped between the rollers by a specific feed length with slip-free rolling of the rollers on a strip surface, wherein the rollers perform a rotation by a specific angle of rotation corresponding to the specific feed length;
• e) Detecting the determined feed length as a reference feed length and the determined angle of rotation of the first roller as a first reference angle of rotation and/or detecting a ratio of the determined feed length and the determined angle of rotation of the first roller as a first reference feed length/angle of rotation ratio;
• and afterwards:
• f) if not already carried out under point c), arranging the material strip provided for an intended feeding to the processing zone of the machine tool between the rollers such that the longitudinal direction of the material strip runs perpendicular to the axes of rotation of the rollers and the material strip is clamped between the rollers;
• g) Advancing at intervals the material strip clamped between the rollers, in each case by a feed length, wherein the rollers perform a rotation at intervals by an angle of rotation;
• h) Detecting for each feed interval the relative position of the rollers to one another and the angle of rotation of the first roller and the feed length, or detecting for each feed interval the relative position of the rollers to one another and the angle of rotation of the first roller and the ratio of the feed length and the angle of rotation of the first roller;
• i) Comparing for each feed interval a currently detected feed length with the reference feed length, a currently detected angle of rotation of the first roller with the first reference angle of rotation, and/or a currently detected ratio of the feed length and the angle of rotation of the first roller with the first reference feed length/angle of rotation ratio;
• j) Calculating for each feed interval the thickness of the material strip from the difference between the reference relative position and the currently determined relative position of the rollers to each other,
• wherein, in the event that the currently detected feed length deviates from the reference feed length, the currently detected angle of rotation of the first roller deviates from the first reference angle of rotation and/or the currently detected ratio of the feed length and the angle of rotation of the first roller deviates from the first reference feed length/angle of rotation ratio, the determined feed length deviation, the determined angle of rotation deviation and/or the determined feed length/angle of rotation ratio deviation is converted via the relationship between the roller diameter, the angle of rotation and the feed length into a deviation of the diameter of the first roller from its diameter at detection of the reference relative position and is taken into account in the calculation of the thickness of the material strip.