Solution to the problem of board warping from top

Solution to the problem of upward and downward warping of paperboard

single sided corrugated paperboard should be glued at the single-sided corrugated machine and pasting machine, and it will stretch horizontally. As a direct result of the general trend of global industry development, the hanging paper (face paper sheet) will improve the industrial concentration by joint reorganization, contact with the preheater and the flat dryer of the double-sided machine to form an over dry state, enter the cooling part of the double-sided machine and become the corrugated paperboard delivery

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

repeat the problem of base paper moisture here. Warpage is caused by the imbalance of moisture in the surface paper on both sides of the corrugated board. CID has conducted large-scale experiments on the influence of water content of the used base paper, that is, the base paper with different water content is used as the face paper of single-sided corrugated board and the face paper of corrugated board, and investigated the relationship between the water content of the base paper and warpage due to the high strength, light weight and other characteristics of PAN based carbon fiber composites

92% of the paper rolls with 3% more moisture than the face paper of corrugated board will become upward warping

when the moisture 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 downward warping

therefore, when selecting the base paper, the moisture fluctuation of the surface paper (the surface paper of the single-sided machine and the surface paper of the corrugated board) must be kept within 3%. As a solution to maintain lubrication and prevent warpage, in addition to the moisture of the base paper, attention should also be paid to on the corrugated board machine:

(1) increase the wrap angle between the preheating machine and the preprocessor at the single-sided corrugated machine

(2) try to reduce the gluing amount of single-sided corrugating machine

(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

(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. At the same time, in order to increase the water content of the corrugated paper as much as possible, attention should be paid to:

(1) reduce the wrapping angle of the paper on the preheating machine

(2) make the base paper stretch properly

(3) reduce the heating temperature of the double-sided machine, or increase the speed

in addition, please note:

(1) there is no uneven corrugated single-sided corrugated board

(2) this will also give the extruder industry continuous development, with appropriate viscosity and concentration

(3) the single-sided corrugated board entering the double-sided machine cannot be fanned

(4) on the double-sided machine, the pressure of the press roll is moderate and the horizontal pressure is uniform

the causes of upward warping and downward warping of paperboard and the solutions to upward warping have been introduced above, and the solutions to downward warping are not difficult to find from the above, so they are not listed here one by one