Flatness Control of the Crossbowed Hot Plate Using Cold Roller Leveling

A crossbow is one of the shape defects caused by width differences between the top and bottom plate surfaces. To improve the plate flatness, leveling must be performed to flatten the crossbowed plate prior to the second manufacturing process. Leveling is a process for minimizing shape defects and enhancing the internal stress uniformity in shape-critical applications. As roller levelers mainly correct shape defects across the plate length, the entire plate width must be worked to correct the crossbow. Owing to the high sensitivity of roll positions in the leveler on the plate geometry, a unique leveling machine setup should be determined for flattening the crossbowed plate. As the problem is complicated by the high inherent nonlinearity and sensitivity, the finite element method has been used to simulate numerically the effect of work roll configurations on leveling efficiency. In order to verify the accuracy of numerical simulations, actual leveling experiments were performed using crossbowed plates. Through the analysis, the leveling strategy for increasing the leveling efficiency of crossbowed plates is validated with a high degree of reliability.