Bending Moment Characteristics on Repeated Folding Motion of Coated Paperboard Scored by Round-Edge Knife

This work deals the creasing characteristics of coated paperboard. It was not clarified to estimate the deformation behavior of creased line from the first peak bending moment M-p1 and the initial gradient C-1 of bending moment. In this study, a new prototype testing apparatus has been developed for seeking the bending moment and the side view picture of creased part during repeated folding motion. The permanent (residual) deformation angles, the variance of residual stiffness and the hysteresis characteristics of bending moment were analyzed for the nominal shear strain (the scoring depth) gamma. The obtained results were as follows: (1) C-1 was characterized with gamma, while the second term gradient C-2 was characterized with gamma and the inverse of tracking angle Theta(-1). (2) By introducing the area of closed curve of second term hysteresis A(CC), it is revealed that the gradient of A(CC) was remarkably varied with Theta at near the peak point M-p1.