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.

幾個基本參數

Several basic parameters

翹曲系數一般用翹曲系數來表示瓦楞紙板拱曲、彎翹的嚴重程度。翹曲系數K為翹曲拱高H與翹曲長度L的比值，如圖1所示。經驗證明：當裱紙后的瓦楞紙板翹曲系數超過0.05時，容易造成模切走位，從而影響模切效率;對成型后的彩盒、彩箱，當瓦楞紙板翹曲系數超過0.03時，會對于彩盒、彩箱的外觀和抗壓能力產生一定影響。因此，瓦楞紙箱生產企業(yè)一般的控制要求是： 裱紙后的瓦楞紙板翹曲系數<0.05;成型后的彩盒、彩箱翹曲系數<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.

紙張伸縮率

Paper stretch ratio

我公司選擇常用的4種紙張做伸縮率實驗，根據實驗數據得出了如下結論。

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)紙張吸收水分后會發(fā)生伸長，在紙張內部水分達到飽和之前，吸收的水分越多，紙張伸長的長度越長。

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

(2)紙張吸收水分發(fā)生伸長時，其豎紋方向的伸縮率很小，幾乎可忽略，橫紋方向的伸縮率很大，且是豎紙紋方向的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)同種同種類型的紙張，定量越高，吸水后伸縮率越小。

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

(4)定量相同的紙張，牛卡紙的伸縮率比涂布紙小，且僅為輕涂布紙的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.紙張紋路

3. Paper texture

紙張紋路是紙張纖維的排列方向。由于原紙一般是長紋(紙張紋路與走紙方向一致，與卷筒轉動軸向垂直)，因為生產瓦楞紙板時，原紙的走紙方向應與原紙紋路一致，即里紙、芯紙的紋路全部與瓦楞方向垂直。

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，裱紙時也要求面紙紋路與瓦楞方向垂直 。因此，裱紙后，面紙、芯紙、里紙的紋路全部一致，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.