Common problems and treatment of sizing machine during internal surface sizing operation

　　Folding problem: this problem has become a big problem during the initial production of light coating. The main reason is that the paper is folded before the press zone after entering the coater. The main reasons are as follows:

　　1) The coating amount is low;

　　2) Incorrect position of sealing plate;

　　3) The moisture content of the whole sheet entering the nip and the quantitative banner difference are large;

　　4) The side spray position is not correct;

　　5) The glue roller is big and big.

　　6) When producing double gummed paper, especially when the side of the paper and the glue outside the edge are uneven, the old sealing block can be replaced or the top of the sealing block can be cut off.

　　Miss coating: there are two phenomena

　　The main reason for this phenomenon is that the coating carries bubbles during operation. The adjustment methods are as follows:

　　1) Adjust the size of the dredge valve;

　　2) Increase the feeding flow;

　　3) Increase the flow rate of defoamer, and adjust the flow rate of defoamer back after the missing coating disappears. If the missing coating only appears at the edge, just adjust the position of the sealing plate.

　　The reason of this phenomenon is complex. It is mainly caused by the accumulation of the coating in the rod seat. The jumping slag scratches the coating and forms a similar phenomenon. It is difficult to deal with this kind of problem, which is usually solved by replacing the rod seat.

　　Dark fold:

　　Horizontal dark fold: the main reason is the instability of both sides of the paper, which is caused by the fluctuation between the two rollers. As long as the air filling pipe under the paper is blown at both ends of the roller, this phenomenon can be eliminated.

　　Longitudinal dark fold: the main reason is that the coating amount suddenly drops and the viscosity rises or the paper sheet before the nip is loose. This dark fold can be adjusted by reasonably adjusting the stability of the coating amount and the tension of the paper sheet before the nip.

　　Coating point:

　　1) The reason for the spray like coating spots on the paper is the paper defects caused by the spray like coating splashed on the paper by the sizing machine roller, and the local coating amount is too high;

　　2) The coating splashed on the paper in the upper roller coating recovery tank.

　　Water drop: water drop formed on the paper caused by excessive side spray or large heat compensation water of roller.

　　Stripe: due to the surface damage of sizing machine roller, the local coating amount is high, and the surface of the roller needs to be ground. The main reason for the surface damage is that the hard impurities in the coating enter the system, and the pressure screen is not used well.