| Popis: |
This work deals with the time-dependent creasing characteristics of coated paperboard. The correlation between the bending strength (resistance) and time-dependent problems on the actual processing phenomenon has not been sufficiently discussed in the past. It is difficult to estimate various time-dependent responses from the initial strength of the creased part, such as the maximum bending moment and the initial gradient of bending moment. In this study, therefore, a prototype testing apparatus has been applied to investigate about the dynamic relaxation of bending moment. In order to reveal the relaxation characteristics of the bending resistance during the folding motion from an initial position up to various tracking angles, a white-coated paperboard of 0.3 mm thickness was scored with a creasing rule and a grooved counter face plate under a specified feed velocity, and then the bending test was carried out by varying the tracking angle. Through this work, the followings were obtained: (1) The relaxation of the bending moment was characterized by an exponential coefficient which was independent to the nominal shear strain and the tracking angle. (2) The relaxation depends on the rubbering condition. |
