When the corrugated board deviates from the flat state, the concave surface downward is called arch, and the concave surface upward is called bending. Slight camber and warping are not quality defects of products. When the degree of camber and warping affects the production, appearance and performance of corrugated boxes, they are regarded as quality defects.
Several basic parameters
Warpage coefficient is generally used to express the serious degree of warping and warping of corrugated board. Warpage coefficient K is the ratio of warping arch height h to warpage length L, as shown in Figure 1. Experience has proved that: when the corrugated board warpage coefficient after mounting is more than 0.05, it is easy to cause die-cutting displacement, thus affecting the die-cutting efficiency; for the formed color box and color box, when the corrugated board warpage coefficient exceeds 0.03, it will have a certain impact on the appearance and compressive capacity of color boxes and color boxes. Therefore, the general control requirements of corrugated box manufacturers are as follows: the warpage coefficient of corrugated paperboard after mounting is less than 0.05; the warpage coefficient of color box and color box after forming is less than 0.03.
Paper stretch ratio
Our company chooses 4 kinds of paper to do the experiment of expansion ratio, and draws the following conclusions according to the experimental data.
(1) The paper will stretch after absorbing moisture. The more water absorbed, the longer the length of paper elongation.
(2) When the paper absorbs moisture, the expansion rate in the vertical direction is very small, almost negligible, and the expansion rate in the horizontal direction is very large, which is more than 10 times of that in the vertical direction.
(3) The same brand and the same type of paper, the higher the weight, the smaller the shrinkage after water absorption.
(4) With the same amount of paper, the expansion ratio of kraft paper is smaller than that of coated paper, and it is only 0.54 times of that of light coated paper.
3. Paper texture
Paper grain is the direction of paper fiber arrangement. Since the base paper is generally long grain (the paper grain is consistent with the paper running direction and perpendicular to the rotation axis of the drum), the paper running direction of the base paper should be consistent with the original paper grain when producing corrugated board, that is, the lines of the inner paper and the core paper are all perpendicular to the corrugated direction.
In addition, when mounting paper, it is also required that the grain of face paper should be perpendicular to the corrugated direction. Therefore, after mounting, the grain lines of face paper, core paper and inner paper are all consistent, and all are perpendicular to the corrugated direction.济南印刷厂讲解的内容 更多的内容 请咨询公司官网http://www.xinfengyinshua.cn/