1. Cardboard bonding
(1) The importance of bonding
Reliable bonding is necessary to form and maintain the properties of the corrugated cardboard frame, and it is also important to the final corrugated box packaging quality. Poorly bonded cardboard can block or stop other post-processing equipment, costing production.
(2) Inspection of bonding quality
The PAT method is a method for measuring the bonding quality in the laboratory. In actual production, operators on the corrugated board production line generally tear off the lining paper to check the bonding quality of the cardboard. If the bonding is good, the lining paper Part of the corrugated core paper fiber should be adhered to the top; if the bonding is not good, the lining paper and the corrugated core paper are completely separated.
(3) Reasons for poor adhesion
(1) Reasons for poor adhesion of cardboard on single-sided machine
① Occurs at the edge of the cardboard
a. The pressure between the lower corrugating roller and the pressure roller is not enough.
b. The parallelism of the lower corrugating roll and the pressure roll is deviated
② Occurs in the middle of the cardboard, and the middle of the corrugating roller is worn due to the change of the width of the cardboard, resulting in insufficient supply of adhesive.
③ Occurs over the entire width of the cardboard
a. The gap between the glue roller and the doctor roller is not set properly, resulting in insufficient (too thin) adhesive film.
b. The glue roller is too far from the lower corrugating roller.
c. The adhesive level in the glue tray is too low.
d. Adhesive quality is not good.
e. The temperature of the corrugating roller is not high enough.
f. The pressure of the pressure roller is uneven or insufficient.
g. Insufficient adhesive coating, insufficient paper preheating, insufficient preheater winding or insufficient temperature.
h. The moisture content of the paper is too high, the winding angle in the preheater and the corrugating core preparer is not enough, or the speed of the single-sided machine is too fast.
(2) The reasons for the poor adhesion of the cardboard on the double-sided machine
① Occurs in the middle of the cardboard
a. The tension of the single-sided corrugated board makes the guide roller (floating roller) excessively deviate, resulting in insufficient adhesive coating.
b. A blower unit can limit this problem due to thermal expansion that does not press enough against the cardboard in the middle of the hot plate.
c. Due to insufficient evaporation in the center of the cardboard, the adhesive cannot be gelatinized completely, if the temperature of the hot plate cannot be increased, the only way is to reduce the speed.
② Occurs over the entire width of the cardboard
a. Insufficient adhesive coating, insufficient preheater wrap, insufficient belt pressure, too fast speed, or too low hot plate temperature.
b. Adhesive film is not enough.
c. Adhesive quality is poor.
2. Washboard phenomenon
The so-called washboard phenomenon refers to the concave phenomenon between the corrugated board and the back of the corrugated peak on the surface of the corrugated cardboard after it is made, and the shape is like a household washboard, so it is called the washboard phenomenon.
(1) The root cause of the washboard phenomenon of corrugated cardboard:
The main reason for this is the improper gluing of the adhesive, which is caused by the excess glue that accumulates on both sides of the peaks. This is especially the case for low basis weight containerboards.
(2) The specific methods to control the phenomenon of cardboard washboard are as follows:
① Adjusting the quantitative of the face paper and using a containerboard with a higher quantitative basis is a direct and effective way to eliminate and reduce the washboard shape (but it will increase the cost);
② The use of high-quality adhesives can reduce the amount of glue applied to the peaks;
③ Control the heating and winding surface of the tissue paper on the pre-heater, because the linerboard paper is too dry, the intake of glue is large, and the phenomenon of washboard is easy to occur;
④ Adjust the parallelism of the glue roller and the paper guide roller of the compound glue machine and the gap between them, and strictly control the pressure degree of the guide roller (pressing roller) to prevent the increase of the amount of glue after the corrugation collapses.
3, Upside down
(1) Single-sided cardboard upside down
Cause Analysis:
① The corrugating roller is worn;
② The gap between the upper and lower rollers is too large;
③ The weight of the tile paper is too large and too thick;
④ The water content of the tile paper is too large;
⑤ The tile paper has poor plasticity without preheater.
Solution:
① Replace the tile roller or grind it;
② Adjust the gap between the two rollers to 0.5mm;
③ Replace the corrugated paper;
④ Increase the preheated wrapping angle of the tile paper;
⑤ Pass the tile paper through the preheater.
(2) Double-sided cardboard upside down
Analysis of the reasons: ① The backing after gluing by the double-sided machine is caused by the too small gap between the gluing roller and the ballast roller; ② The floating ballast roller on the conveyor belt cannot move freely up and down after the drying machine. And press the corrugated deformation; ③ the amount of glue is too large, the corrugated paper absorbs a lot of water in the glue and becomes soft, and it falls to one side along the running direction of the dryer; ④ the quality of the corrugated paper is inferior.
Solution: ① Adjust the gap between the double-sided machine, the ballast roller and the gluing roller to be slightly smaller than 0.2mm of the single-sided cardboard, and insert the single-sided cardboard longitudinally between the ballast roller and the gluing roller, which can be freely It is better to insert and drive the ballast roller to rotate the corrugated without deformation; ②Adjust the floating roller on the conveyor belt of the dryer to move freely; ③Reduce the amount of glue applied to evenly distribute the corrugated peaks without flowing into the trench; ④ Replace the corrugated paper.