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.

几个基本参数

Several basic parameters

翘曲系数一般用翘曲系数来表示瓦楞纸板拱曲、弯翘的严重程度。翘曲系数K为翘曲拱高H与翘曲长度L的比值，如图1所示。经验证明：当裱纸后的瓦楞纸板翘曲系数超过0.05时，容易造成模切走位，从而影响模切效率;对成型后的彩盒、彩箱，当瓦楞纸板翘曲系数超过0.03时，会对于彩盒、彩箱的外观和抗压能力产生一定影响。因此，瓦楞纸箱生产企业一般的控制要求是： 裱纸后的瓦楞纸板翘曲系数<0.05;成型后的彩盒、彩箱翘曲系数<0.03。

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.

纸张伸缩率

Paper stretch ratio

我公司选择常用的4种纸张做伸缩率实验，根据实验数据得出了如下结论。

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)纸张吸收水分后会发生伸长，在纸张内部水分达到饱和之前，吸收的水分越多，纸张伸长的长度越长。

(1) The paper will stretch after absorbing moisture. The more water absorbed, the longer the length of paper elongation.

(2)纸张吸收水分发生伸长时，其竖纹方向的伸缩率很小，几乎可忽略，横纹方向的伸缩率很大，且是竖纸纹方向的10倍以上。

(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)同种同种类型的纸张，定量越高，吸水后伸缩率越小。

(3) The same brand and the same type of paper, the higher the weight, the smaller the shrinkage after water absorption.

(4)定量相同的纸张，牛卡纸的伸缩率比涂布纸小，且仅为轻涂布纸的0.54倍。

(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.纸张纹路

3. Paper texture

纸张纹路是纸张纤维的排列方向。由于原纸一般是长纹(纸张纹路与走纸方向一致，与卷筒转动轴向垂直)，因为生产瓦楞纸板时，原纸的走纸方向应与原纸纹路一致，即里纸、芯纸的纹路全部与瓦楞方向垂直。

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.

此外，裱纸时也要求面纸纹路与瓦楞方向垂直 。因此，裱纸后，面纸、芯纸、里纸的纹路全部一致，且全部垂直于瓦楞方向。

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.