Metal-strip warped-shape estimation method, metal-strip acceptability determination method, metal-strip manufacturing method, and metal-strip warped-shape estimation equipment

Metal-strip warped-shape estimation equipment that estimates, based on a shape in a width direction of a metal strip in a tension-applied state where tension in a longitudinal direction is applied, a warped shape in the width direction of the metal strip in a no-tension state where the tension is relieved, the metal-strip warped-shape estimation equipment comprising:

• a widthwise-shape measurement device that measures a widthwise shape distribution of the metal strip in the tension-applied state;
• and
• a metal-strip warped-shape estimation device that estimates the warped shape in the width direction of the metal strip in the no-tension state,
• wherein the metal-strip warped-shape estimation device includes:
• an acquisition section that acquires the widthwise shape distribution of the metal strip from the widthwise-shape measurement device;
• an approximation-curve calculation section that calculates an approximation curve that approximates the widthwise shape distribution, measured by the widthwise-shape measurement device, with a quadratic curve or a circular arc;
• and a warped-shape estimation section that estimates the warped shape in the width direction of the metal strip in the no-tension state using the widthwise shape distribution and the approximation curve.