Method of measuring camber

A method of measuring camber in a sheet of metallic material having upper and lower surfaces and first and second longitudinal edges and a width W comprising the steps of:

• (a) displacing said sheet in a path between fixed guides in a plane of said sheet perpendicular to said width such that a point on a center of said sheet travels a predetermined distance past a datum line perpendicular to said path, said sheet being directed by engaging said edges against said guides;
• (b) measuring a length of said sheet adjacent to said first longitudinal edge thereof which moves past said datum line when said sheet is displaced said predetermined distance by bringing a first measuring wheel into contact with said sheet on one of said surfaces adjacent to but spaced from said first longitudinal edge and generating a first number of pulses proportional to an amount of rotation of said first wheel, said first number of pulses having a value A proportional to said first edge length;
• (c) measuring a length of said sheet adjacent to said second, opposite longitudinal edge whereof which moves past said datum line when sheet when sheet is displaced said predetermined distance by bringing a second measuring wheel into contact with said sheet on one of said surfaces adjacent to but spaced from said second longitudinal edge and generating a second number of pulses proportional to an amount of rotation of said second wheel, said second number of pulses having a value B proportional to said second edge length;
• and
• (d) calculating camber at a centerline of said sheet, expressed as a radius of curvature R.sub.C of said sheet, by the equation ##EQU13##