The four most common problems of corrugated Packaging Boxes cardboard process

Feb 17, 2022

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1. Cardboard warping

Under normal circumstances, there are 6 phenomena of warping and deformation of corrugated cardboard, the most common ones are:

1. Lateral warping

The reasons are: the moisture content of the inner base paper is too high (or the moisture content of the surface paper is low); the single-sided corrugated adhesive has too much moisture; the quantitative grades of the inner and surface papers are too different.

Solution: (1) Increase the winding surface of the lining paper on the drum dryer of the single-sided machine; (2) Reduce the winding surface of the lining paper on the double-layer preheater; (3) Close some of the flat dryer steam valves; ( 4) Improve the running speed of the compound machine; (5) Reduce the gap between the squeegee roller, the sizing roller and the lower corrugating roller, and reduce the amount of sizing for single-sided corrugation; (6) Replace the lining paper that seriously exceeds the moisture requirement.

2. Lateral warping

The reasons are: the moisture content of the base paper is too high; the temperature and speed of the heating part are abnormal.

Solution: (1) Increase the heating winding surface of the surface paper on the double-layer preheater; (2) Use a better viscosity adhesive to reduce the amount of glue on the compound machine; (3) Reduce the paper in the single-sided machine The winding surface on the drum dryer; (4) Reduce the production speed at the compound machine; (5) Correctly adjust the production line speed and the steam valve of the flat dryer to match; (6) Replace the surface paper that seriously exceeds the moisture requirement.

2. Pseudo-bonding of cardboard

The so-called false adhesion of cardboard refers to a phenomenon that the paper, lining and corrugated paper can be peeled off at will after the cardboard leaves the machine.

The main reasons are: (1) the viscosity of the adhesive is not enough or has deteriorated; (2) the speed of the corrugating machine or compound locomotive is too fast; (3) the pressure roller of the corrugating machine is uneven or the corrugating roller is worn; (4) compounding The gap between the glue rollers of the gluing machine is too large; (5) the moisture content of the paper is too high. Solution: (1) Improve and stabilize the quality of the adhesive. The relevant information indicates that the adhesive viscosity is generally 60S-90S in winter and 90S-120S in summer. The viscosity of the seven-layer box is generally about 305 slower than that of the three-layer box; (2) ensure that the steam pressure is 1.0MPa-1.2MPa, and the temperature of each roll body and flat drying cylinder is about 160 degree ; (3) The domestic corrugated roll has a production capacity of 3 million When the long rice is 3.5 million long meters, it must be replaced in time.

3. Washboard phenomenon

The so-called washboard phenomenon refers to the concave phenomenon between the corrugated board and the back of the flute 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.

The root cause of the washboard phenomenon of corrugated cardboard is mainly due to the improper gluing of the adhesive, which is caused by the excessive glue that gathers on both sides of the corrugated peak. This is especially the case for low basis weight containerboards.

The specific methods to control the phenomenon of cardboard washboard are as follows: adjusting the basis weight of the face paper and using a containerboard paper with a higher basis weight is the most direct and effective way to eliminate and reduce the washboard shape (but it will increase the cost); the use of high-quality adhesives can reduce the The amount of glue applied to the peaks; control the heating and winding surface of the face paper on the pre-heater, because the containerboard paper is too dry, the intake of glue is large, and the phenomenon of washboard is easy to occur; adjust the glue roller and paper of the compound glue machine. The parallelism of the guide rollers and the gap between them, and the pressure level of the guide rollers (pressing rollers) are strictly controlled to prevent the increase of the amount of glue after the collapse.

4. Control of moisture content of cardboard

In the process of producing corrugated cardboard, it is very important to control the moisture content of the cardboard. When the moisture content is too high, the processed cardboard will be soft, not stiff, and the box will collapse easily after being formed into a box. When the moisture content is low, the processed cardboard is hard, brittle, and easy to burst after being packed into a box. The control of cardboard moisture is a relatively complicated matter, which is mainly determined by the following two factors:

The moisture content of the raw paper entering the factory should be strictly controlled. According to the current standard: the moisture content of the raw paper in the delivery state should be (8±2) percent . It is best to set up a separate warehouse for storing the base paper, the temperature is generally (18 ± 3) degree , and the humidity is generally (35 ± 5) percent . Do not put it in the open air, otherwise it will easily cause moisture changes and the ends will be different from the middle.

Temperature is one of the determining factors affecting the quality of corrugated cardboard. It can not only adjust the moisture of the base paper, but also make the base paper heat up, which is an important condition for the solidification of the paste. Therefore, the cardboard production line is equipped with many preheaters and flat dryers to adjust the moisture content of the base paper and single-sided paper, and to solidify the paste to finally achieve the purpose of bonding.

In order to effectively control the moisture content of the finished corrugated board, the following matters must be paid attention to:

If the moisture content of the cardboard is too high and the temperature of the preheating roller cannot meet the requirements, the steam pressure of the boiler must be increased to make the steam supplied by it reach saturated steam. Generally, the steam pressure should be kept at 1.1Mpa±0.2Mpa.

If the moisture content is low, the paper guide roller should be adjusted to reduce the preheating area. At the same time, the spray device (wetting roller) on the single-sided machine should be fully utilized to spray the base paper to increase the moisture content of the base paper to make it meet the standard requirements.

When the flat dryer is working, it cannot be stopped until it is a last resort. The speed of the single-sided machine should be increased before replacing the base paper, and more paper should be accumulated on the bridge; the speed of the multi-functional machine should be reduced after receiving the signal, and the speed should be increased after the single-sided machine has finished receiving the paper. If the equipment fails and must be stopped, the conveying felt should be lifted to prevent excessive loss of moisture from the cardboard that stays on the flat dryer.

For single{{0}}sided machines, it is necessary to adjust the gap between the rubber roller and the rubber scraping roller. Under normal circumstances, the gap between the gluing roller and the scraping roller is 0.2mm to 0.25mm, and the gap between the gluing roller and the main corrugating roller in the hot state should be 0.{{10}}2mm larger than the thickness of the corrugated paper used. For the double-sided machine, the gap between the scraping roller and the gluing roller is also 0.2mm to 0.25mm, and the gap between the pressing roller and the gluing roller should be 0.05mm to 0.1mm smaller than the height of the single-sided corrugated cardboard that passes through. And the gap between the two ends of the two rollers should be consistent, which can be measured with a feeler gauge.

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