Main causes of corrugated board bending
Corrugated flatness is one of the important indexes in cardboard production, which is directly related to printing, die-cutting, and/or slotting corner cutting. Poor flatness, i.e. corrugated board a variety of arched, mechanical adsorption printing machine is easy to get stuck, resulting in scrap cardboard and stop cleaning to restart; In two-color printing or multi-color printing, it is easy to produce uneven inking, inaccurate color registration, color folding, and gap. Flexo Printer Slotter size displacement, carton up and down swing cover overlap or do not fit; Die cutting feed will also produce stuck and size displacement and other defects, are likely to cause scrap the whole piece of cardboard or equipment damage so as to cleaning and restart. In short, the flatness of the cardboard will make it inconvenient to feed and cause secondary waste in the production process.
In order to improve the flatness of corrugated board, ensure the product quality pass rate and normal production efficiency, we constantly test and analyze the carton production practice, and explore some improved methods.Here is a rough summary of the following, only for reference.
1. Shape of Poor Corrugated Board Flatness
Poor flatness of the appearance of corrugated board is generally divided into three kinds: transverse arch, longitudinal arch and arbitrary arch. Transverse arch, it is to point to the arch that produces along corrugated direction. Longitudinal arch, is refers to the cardboard along the production line speed direction of the arch. arbitrary arch is that rises and falls in any direction. Linerboard surface arch is called a positive arch, inner linerboard surface arch is called a negative arch, linerboard and inner linerboard fluctuating respectively are called positive and negative arch.
2.The Main Reasons Affecting the Flatness of Cardboard
1.Different types and grades of linerboard and inner linerboard. Kraft paper, imitation kraft paper, corrugated paper, tea board paper, high strength corrugated paper etc, and they are divided into A, B, C, D, E class. According to the paper on the material,generally,linerboard is better than inner linerboard.
2.The main technical parameters of the linerboard and inner linerboard are different. From the perspective of carton performance or the user's cost reduction, the linerboard and inner linerboard are required to be different, usually:
(I) The quantity is different. Some quantity of linerboard are larger than inner linerboard, some are aller.
(2) Moisture content is different. Due to the differences of supplier, transportation inventory and other environmental humidity. Some moisture content of linerboard are larger than inner linerboard, some are aller.
(3) The quantity and moisture content are both different. One is the quantity of linerboard is greater than inner linerboard. The moisture content of linerboard is greater than inner linerboard. Or moisture content of liner board is less than the inner linerboard. Second, the quantity of liner board is less than inner linerboard, the moisture content of linerboard is greater than inner linerboard, or the moisture content of linerboard is less than inner linerboard.
3. The moisture content of the same batch of paper is different. The moisture content of one part of the paper is different from that of the other part, or the two ends of the paper, the outer edge and the inner core.
4. Paper by the pre-heater (Wrap Angle) heating surface length selection and adjustment is not appropriate, or (Wrap Angle) heating surface length can not be arbitrarily adjusted. Former operation is improper leads to latter equipment limitation, resulting in affecting preheat drying effect.
5. Do not use the vapor spray device correctly, or there is no spray device on the device. Do not add any moisture to the paper.
6. The paper after the preheating of moisture loss time is insufficient, or the environment humidity, poor ventilation, improper speed of the production line.
7. Single Facer paper corrugating machine, Glue Applying Machine on the amount of improper, uneven, and cause uneven shrinkage rate of cardboard.
8. Insufficient steam pressure, instability, steam trap and other accessories damage or drain value is not clean, leading to the Pre-conditioner can not work normally and steadily.
3.Solution
1.Reduce the paste amount of the single facer and increase the paste amount at the place of the paste machine. Because the two correspond to each other, they increase here and decrease there.
2.Increase the moisture of the tissue paper, spray water on the tissue paper to increase its humidity, and reduce the wrapping angle of the paperboard on the preheating cylinder. Doing so can also improve the moisture of the tissue paper.
3.Reduce the temperature of the hot plate, so that the moisture of the lower paperboard is not easy to transfer upward. At the same time, it can improve the speed and solve the problem of transverse upturning of the paperboard.
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