The Impact of Corrugating Roll on Corrugated Cardboard and Their Maintenance

The corrugating roll is the core component of the single-facer, and its quality is a key factor in enhancing the efficiency of both the single-facer and the entire corrugated cardboard production line. On the corrugated cardboard production line, due to inertial vibration and continuous friction of the corrugated paperboard, the corrugating roll is easily worn down, and the quality and size of the raw paper are affected. Therefore, its maintenance is also a decisive factor affecting overall production efficiency.

What Impact Do Corrugating Rolls Have On Corrugated Cardboard?

The corrugated edges pressed by new corrugating rolls generally meet the quality standards in terms of height. However, after a period of use, the corrugating rolls often experience the following effects due to wear:

• When the corrugating roll shaft head and bearing are worn or damaged, resulting in loose corrugating roll, poor parallelism and damaged teeth, quality problems such as flat corrugation, collapsed corrugation, corrugated cardboard, high and low corrugation delamination, and air bubbles are likely to occur.

• If foreign objects are stuck in the flute groove of the corrugating roll, it will not only cause the corrugated cardboard to have skewed, inverted or collapsed flutes, but also easily lead to poor adhesion and reduce the strength of the corrugated cardboard.

• When the corrugating roll is used for a long time and the "concave" phenomenon occurs, it will lead to uneven glue application, resulting in excessive glue application on the effective parts of the corrugated cardboard, and some parts will not be glued at all, causing the corrugated cardboard to fall off and bubble.

• When corrugating rolls become worn, it tends to cause the corrugated medium to flutter, leading to poor adhesion and uneven flute heights. This makes it more difficult to control the gap and pressure between the corrugating roll and the pressure roll, resulting in phenomena such as corrugation collapse, corrugation cracking, and uneven thickness.

• If the teeth of the corrugating rolls are worn, it will directly affect the formation of the corrugated cardboard, leading to uneven formation and, consequently, uneven adhesive application.

• When the bearings of the corrugating rolls exhibit a certain degree of wear, the parallelism of the rolls' operation is compromised, which reduces the quality of the corrugated cardboard and accelerates wear on the rolls themselves.

Maintenance of Corrugating Rolls

• Use high-quality corrugated base paper as much as possible. Low-priced and low-quality corrugated base paper will aggravate the wear and tear on the corrugating rolls and shorten their service life.

• Install a Limiting Device and Accurately Adjust the Pressure and Gap Between The Corrugating Roll and The Pressure Roll

In the single face machine of the corrugated cardboard production line, when the corrugated peaks of the corrugated cardboard coated with adhesive are bonded to the face paper, a certain pressure is required between the corrugating roll and the pressure roll to ensure the bonding effect. If the single-facer lacks a limit device or some limit devices are unreliable, the corrugating roll may come into direct contact with the pressure roll, damaging the surface of the pressure roll. By installing a limiting device and properly adjusting the gap and pressure between the pressure roller and the corrugating roll, damage to the corrugated roll and pressure roll caused by improper gap control can be avoided.

• Real-time Monitoring of Corrugating Roll Wear

Wear on hardened steel corrugating rolls occurs linearly; therefore, the flute height requires periodic measurement to determine the roll's expected service life and replacement schedule, thereby ensuring the quality and efficiency of the corrugated cardboard production line.

• Grinding of Corrugating Rolls

After the corrugating rolls are worn, a distinct stepped pattern will appear on the roller surface. The middle part of the roller will be the most worn, which will cause uneven pressure on the pressure roll clamp and make it difficult to apply adhesive evenly. Grinding can be performed using diamond lapping paste; this process requires skill to avoid damaging the critical coating on the roll. (If the single facer is equipped with a fixture, the process is more precise and easier to execute, and precision grinding can significantly extend the roll's service life. Severely worn corrugating rolls must be replaced promptly.)

• Regular Alignment is Required to Ensure The Parallelism of The Corrugating Rolls

If the corrugating rolls cannot be kept parallel, it will not only affect the quality of the corrugated cardboard, but also the life of the corrugating rolls. The pressure of the corrugated roll can be adjusted by changing the paper frame or the grade of the corrugated core paper (the pressure should be reduced appropriately to prevent metal-to-metal contact at the journal). Making correct adjustments when necessary minimizes journal damage and extends roll life; more importantly, it ensures the rolls remain parallel within the machine. This can be verified using telegraph paper: inserting the paper between the rolls reveals the relative positions of the upper and lower rolls, and any subsequent displacement indicates a potential machine issue.

• Perform Regular Cleaning to Extend The Service Life of The Corrugating Rolls

Removing paper dust, carbonized adhesive, and other contaminants helps reduce wear on the corrugating rolls. Large metal particles can damage the rolls; therefore, the corrugating rolls and the single facer must be kept sufficiently clean to prevent large particulate impurities from passing between the rolls.

• Lubrication of Corrugating Rolls

Avoid letting the corrugating rolls idle, release the pressure and stop the machine immediately after production is completed. If it is a single-facer, it should be kept rotating before stopping to lubricate the corrugated rolls. Since the bearings for the corrugating rolls and pressure rolls operate under high temperature and high pressure, adequate lubrication is essential. The lubrication system should be disassembled and inspected monthly to ensure proper flow of lubricating oil, so that the bearings are properly lubricated. This is to prevent old bearings from causing vibration, which can shorten the life of the corrugating rolls, cause wear, and reduce the quality of the corrugated cardboard.