Causes and Countermeasures of curling of the most

Reasons and Countermeasures for cutting thin paper printing sheets curl

in the process of cutting thin paper printing sheets (such as dictionary printing sheets, etc.), printing sheets curl, warp and other phenomena often occur, affecting the progress and quality of cutting processing. It is analyzed that the main reason is the imbalance between the moisture content of the printing sheet and the ambient temperature and humidity, and the following methods can be adopted to solve it

1. Wet removal

because the water content inside the printing sheet is lower than that in the air, the radial section after cutting must quickly absorb water to achieve the corresponding balance. So I hope I can help you! Properly reduce the moisture in the indoor air to avoid curling of the radial section after cutting. Solution: using the dehumidification function of the air conditioner to remove excess moisture in the indoor air can effectively achieve the purpose of dehumidification. The relative humidity is 50% RH and the temperature is 20 ~ 29 ℃. When the temperature and humidity meet the standard requirements, the printing sheet is not easy to curl and deform

2. Smashing method

if the paper curls after printing, it can be solved by smashing method. First turn over the cut sheet, hit the curled sheet with many broken lines by hand, and use the support force between the broken lines to forcibly change the bent sheet to make it relatively flat

3. Paper drying method

paper drying method is to use the paper drying machine to ventilate and dry the cut or uncut white paper, so that the internal humidity and air humidity of the paper are relatively balanced, and it is not easy to deform in printing and post press processing, which can improve the printing quality and reduce a lot of trouble in the binding process

in addition, in order to ensure the reasonable moisture content inside the paper (about 5%), attention should also be paid to the stacking position of the paper. It is not suitable to lean against the wall, against the window, against the heating (in winter), and it is not allowed to put it in the open air, so as to avoid being too dry, destroying the reasonable moisture content of the paper, and causing the uneven warpage of the paper

4. Dot line cutting method

in the traditional paper impact table, the tail line of the printed sheet is usually a vertical line, but sometimes the printed sheet is irregular serrated, so it is very accurate to observe the front and back lines of the printed sheet

how can it be cut to the specified line? Through the careful observation and study of the cutting process and the equipment used in the pure oxygen technology of chemical coke, as well as the printing machine, we have found a law: all the prints that deviate from the vertical line (the stack of prints after the collision should be the vertical line formed by the combination of tail lines) are skewed and uneven. To be exact, all the prints that are not at right angles deviate from the vertical line. So how to solve and deal with it? We draw the following conclusions from many aspects of discussion and analysis:

(1) to fundamentally solve the problem, we need to make the cut paper 90 °

(2) the solution to the cutting method of finished printing sheets that affects plant growth, that is, "dotted line cutting method"

to explore this method, we must first understand the paper feeding mechanism of the printing machine. The paper feeding mechanism of the printing machine is that Feida transports the paper to the paper feeding table, then sends the paper to the front stop gauge through the belt drive, and then pulls the paper to the specified position through the side gauge. The paper sent to the paper feeding board can be handed over to the teeth after two actions:

the first action is the longitudinal movement, that is, the forward movement when it comes; The second action is the horizontal action, which is the action of pulling the gauge. It is observed that (5) the annual output of 250000 tons of aluminum plate, strip and foil project of Hercules aluminum is fully put into operation. If the paper sent to the front stop gauge is less than 90 ° near the side of the pull gauge, its corner tip will exceed the pull gauge; For paper larger than 90 ° (on the side of the pull gauge), the tail side will also exceed the pull gauge. When the crux is found, there is a solution. The paper feeding positioning of printing is composed of points and lines. The points are determined by the pull gauge bearing, and the lines are formed by the front stop gauge. Through the understanding of the printing machine, in order to cut out more accurate finished products, we decided to transform the paper collider. Transform the paper bumping table into a dotted line structure

specific method: add a board about 100mm wide and 20mm thick on the original paper impact table, and its length is about higher than the height of the side plate of the original paper impact table, and put it in the position of the pull gauge. With this method of page bumping, the printed sheets are very in place, and the bumped sheets also meet the requirements of cutting

but the cutting method did not change, and it still could not meet the ideal requirements, so a cutting device was added

specific method: fix it on the paper pusher with a board of the same specification. Through measurement and practice, nest the double strand No. 8 iron wire into a horseshoe shape at 110 ~ 120mm from the side of the paper pusher (the position of the drawing gauge of the printing machine), one end is stuck on the board, the other end is stuck behind the paper pusher, and the cutting thickness of each stack should be 70mm. This method is convenient and flexible, and does not affect the structure of the cutter. As long as the overprint is accurate, it can be cut beautifully, improve the reliability of high-quality products, reduce the loss rate of "bleeding" caused by cutting and the cost loss caused by re printing, and improve work efficiency. After more than 10 years of application, the effect is very good