Common problems and maintenance of the hottest cor

Common problems and maintenance of corrugated board production line (V)

5 main causes and Countermeasures of various warps

5.1 upward warping

single sided corrugated board should be glued at the single-sided corrugated machine and the pasting machine, and it will stretch horizontally, while the hanging paper (face paper sheet) forms an over dry state due to direct contact with the preheater and the flat drying cylinder of the double-sided machine, and it will be sent out as corrugated board after entering the cooling part of the double-sided machine. When the corrugated board is exposed to the air, in order to achieve water balance, the corrugated side with large water content releases water and shrinks at the same time; The dried vermicelli paper absorbs water and elongates, resulting in upward warpage. If the above situation is opposite (in fact, the bonding speed is too fast compared with the drying capacity of the flat dryer), it will produce downwarping

92% of the paper rolls with 3% more moisture than the face paper of corrugated board will become upward warping. When the water content of the face paper with corrugated board is 3% more than that of the face paper with single corrugated board, 75% of the paper roll becomes lower warpage. Therefore, when selecting the base paper, the moisture fluctuation of the facing paper (we will send you the detailed technical parameters of the product by fax or email after the facing paper of the single-sided machine) must be kept within 3%

as a solution to warpage, in addition to the moisture of the base paper, in 8. Hammer radius: d25mmd90mm corrugated board machine, we should also pay attention to:

5.1.1 increase the wrapping angle between the preheating machine and the preprocessor at the single-sided corrugated machine

5.1.2 try to reduce the gluing amount of single-sided corrugating machine

5.1.3 reduce the accumulation of single-sided corrugated board on the bridge, and try to keep the speed of single-sided corrugated machine consistent with that of double-sided machine

5.1.4 try to reduce the glue amount of corrugated board at the pasting machine

the above four items are all set to solve the problem of cardboard warping and minimize excessive moisture when single-sided corrugated cardboard enters the double-sided machine

5.2 S-shaped warping

in terms of production materials,

upper warping and lower warping are simple warping, and S-shaped warping and diagonal warping described later are very troublesome warping. In case of such warping, the paper sheets shall be turned 180 degrees in a group at the paper receiving place of the production line before stacking. At the same time, when this warpage is serious, in addition to stacking with the above method, heavy objects should be added to flatten the warpage, otherwise it will cause obstacles in the subsequent box making process

the cause of S-shaped warpage is:

5.2.1 horizontal wet spots on the hanging paper roll

5.2.2 there is a large amount of moisture at the edge of the roll of Noodle paper

5.2.3 the heating temperature of the double-sided machine is uneven

from the above three points, it is concluded that the main key to overcome S-shaped warpage is that the water content of the base paper should be uniform, followed by the control temperature of the double-sided machine should be uniform

5.3 warpage in the length direction

the warpage in the length direction of corrugated board has nothing to do with the base paper, which is caused by the tension adjustment in the production process of corrugated board. That is, the tension of the corrugated paper on the paper rack and the three-layer preheating machine is too tight, and the tension difference between the corrugated paper and the single-sided corrugated paper is too large. At the same time, the tension of the face paper of corrugated board is too tight, which is also one of the reasons for the length error on the paper cutter. The solution is to reduce the difference in tension between single-sided corrugated paper and corrugated paper in operation

5.4 diagonal warpage

diagonal warpage is the warpage produced by the combination of longitudinal and transverse warpage. The main reasons are that there are too many single-sided corrugated boards on the bridge, which become overloaded, the tension on the single-sided corrugated board is too large (the tension is the cause of longitudinal warpage), and the warpage is upward, downward or S-shaped. As mentioned above, it is caused by the moisture difference of corrugated board destroying the balance of expansion and contraction. Therefore, to solve diagonal warping, we need to comprehensively consider the above conditions, eliminate the above adverse conditions one by one in the operation, and observe while operating. For example, water can be sprayed on single-sided corrugated board or face paper to balance the water content of the board; The tension of the paperboard can be controlled by adjusting the tension of the paper by adjusting the brake of the paper release rack, adjusting the wrapping angle of the preheating machine, and adjusting the wrapping angle of the preprocessor; It can control the speed of the corrugated board production line to operate under a stable condition, and reasonably reduce the accumulation on the bridge without overloading it