Estimation of bending characteristics of creased paperboard using 45° tapered groove against unbalanced punch indentation

Abstract

In a creased line processing of paperboard, deviation error between a groove of counter plate and a creasing knife is important for assuring the quality of creasing profile. It seems that a tapered (biased) groove of counter plate makes an unbalanced punching position of creasing knife well-adjusted in a certain range. In this work, the effect of a 45° tapered groove of a 1.5mm counter face plate on the eccentricity of crease bulging of a 0.43mm white-coated paperboard was compared with that of a rectangular groove counter plate (0° tapered). After scoring the paperboard across the fiber grain direction, using the rule deviation of e= 0.0~0.4mm and the indentation depth of creasing knife d= 0.3~0.6mm, the surface profile of scored zone was observed and folding tests and in-plane tensile test were carried out. Through the experiments, it was found that (i) a certain extent of asymmetric profile of scored surface was improved when observing the surface profile before folding, (ii) the changing range of bending moment resistance at the 90° bending test was reduced, (iii) the crease deviation at 180° folding test was reduced, and (iv) the in-plane tensile strength of 180° folded specimen was relatively large, compared to that of the rectangular groove.

Keywords

• folding
• shear
• bending
• creasing
• eccentricity
• deviation
• paperboard