In the production of corrugated paperboard, changes in the moisture content of the base paper, improper operation, and environmental changes may cause unevenness in the production of paperboard, which is called warpage.
7.1 The main cause of warpage on corrugated cardboard production line and its influencing factors
The most fundamental reason for the warpage of corrugated board is caused by the difference in the size change of the surface of the corrugated board and the size of the paper.
The change in inch is due to the fact that the water content of the paper in the surface of the board is different. After the corrugated board is out of the double-sided machine, the water balance is achieved. The paper with high moisture content releases water and causes the paper to shrink. The paper with low water content absorbs water and causes the paper Elongation causes the difference in size to cause the board to warp. Contact Shanhai Liuxiang General Euipments for More info.
The factors that cause the above changes in water content can be analyzed from the following factors:
7.1.1 The nature, type and moisture content of the surface paper
In general, if the inner paper is 3% higher than the water content of the facial tissue, 92% of the cardboard is warped; if the facial tissue is 3% higher than the inner paper,
In moisture, 75% of the board is warped on corrugated cardboard production line.
If the moisture distribution in the full width of the base paper is not uniform, S-curvature tends to occur.
In addition, due to the different types of base paper, such as the degree of stretching of kraft liner board and tea board paper, due to the difference in fiber composition. system
Depending on the method of manufacture, the combination of two grades of corrugated cardboard, grade A and grade C, is prone to warping.
If the quantitative weight difference between the paper surface is also very different, it is easy to cause warping.
7.1.2 Ambient temperature and tension
The ambient temperature of the workshop also has an effect on the warpage of the cardboard, such as in the summer when the moisture in the air is higher than in the winter, the cardboard is
In an environment like this, it is easy to absorb the moisture in the air in order to achieve the moisture balance, which causes warpage due to the difference in the dimensional change of the paper.
In addition, the tension of the paper base paper tray brake, the preheater tension, etc., also cause the paperboard to shrink laterally.
(3) Mechanical Equipment and Operation
The warpage is caused by the difference in operation caused by the difference in moisture content of the paper in the paper surface.
(4) Characteristics of adhesive and adhesive amount
Different glue production process, the difference in the amount of adhesive can cause differences in the board moisture content and warpage.
7.2 Types of Corrugated Board Warpage Corrugated Cardboard Production Line
The following are the types of warp board warpage
(1) Longitudinal Warpage (A) Longitudinal Warpage (B) Longitudinal Warpage
(2) Lateral Warpage (A) Lateral Warpage (B) Lateral Warpage
(3) S-warping (A) Bi-directional warping