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Knowledge arrangement of corrugated paperboard flatness
Corrugated board is a kind of composite board used to make corrugated boxes, which is formed by bonding the box board and the corrugated base paper. The surface shall be flat and clean without defects such as lack of materials and thin edges. Therefore, the flatness of corrugated board is an important index. It is directly related to the quality of product printing, die cutting or slotting and corner cutting. There are three main forms, including transverse arch, longitudinal arch and arbitrary arch.
The flatness of corrugated board is related to several factors, and the quantitative and moisture content of surface paper are different. First, the quantitative content of face paper is greater than that of inner paper, and the moisture content is greater than or less than that of inner paper. Second, the quantitative content of face paper is less than that of inner paper, and the moisture content is greater than or less than that of inner paper. Insufficient and unstable steam pressure, damage of steam trap and other accessories or final drainage of accumulated water in the pipeline lead to the failure of the preheater to work normally and stably. Improper selection and adjustment of the length of the heating surface (wrap angle) of the paper through the preheater, or the length of the heating surface (wrap angle) can not be arbitrary, which affects the preheating and drying effect.
How to improve the flatness of corrugated board after it is affected? Increase the length of the heating surface (wrap angle) of the preheater for the paper with high moisture content, ventilate with an electric fan, increase the time of moisture emission, and slow down the speed of the production line; The moisture content of the paper is reduced through the preheater (wrapped angle), the length of the heating surface is reduced, natural ventilation and steam spray are used to speed up the production line. The base paper provided by the supplier is required to have qualified and stable quantitative and moisture content, avoid rain wetting during transportation, loading and unloading, and maintain basically constant environmental humidity during storage in the plant. The guide wheel and tensioning wheel of the Liwa paper in front of the three-layer preheater increase the movement resistance. After proper adjustment, the original longitudinal arch can disappear.
The production of corrugated board has higher and higher requirements for flatness, and the unqualified paperboard will be stopped or withdrawn automatically by the packaging production line. Therefore, we should pay attention to this aspect in production and strictly follow the production requirements.