Corrugated Cardboard Adhesion Problem Consolidation--Solution of Bad Adhesion (Part 2)

(c) Corrugated board machine mechanical factors

Corrugated board mechanical factors are mainly: the accuracy of the core parts corrugated roll, hardness and degree of wear: the advanced nature of the corrugated board adhesive device; the structure of the hot part; whether to use automatic paper receiving device, etc.

Corrugated Roller: Corrugated Roller is often compared to the heart of a corrugated board machine, and its position is very important.

1) An important reason for the poor adhesion of corrugated boards produced with new corrugating rolls is that corrugating roll accuracy is not high. The solution is to use high-precision corrugating rollers. The corrugation produced on a banner has a small difference in height, and less adhesive is used to achieve the desired adhesion.

2) The common corrugating roller surface is chrome plated to increase the hardness. Since the middle and low grade corrugated paper has a certain amount of sand, the main component of the sand is silicon dioxide, which is second only to diamond in hardness, so it is more chrome-plated on ordinary corrugated roller surfaces. severe. Common carton manufacturers produce many kinds of corrugated cardboard specifications, such as the use of tile width 2200mm, specifications may be from 1200mm to 2200mm, all kinds of high middle and low grades, plus long-term paper in the middle, just a few months, The height of the corrugating roller may be lost. This kind of corrugated board produced under the conditions of the underwent poor adhesion or even no adhesion in the middle. In order to obtain the ideal bond in the middle, the pressure roller pressure has to be increased, but this is only an expedient measure, and the time is not long. This situation is even more serious. The pressure roller pressure is increased to the ends of the board paper and is broken by the corrugating roller. Unable to get glued. The solution to this situation, in addition to avoiding the use of corrugated base papers with high sand content, integrates small specifications into large ones (where necessary, uniform use and reasonable production), and replacement of new corrugating rolls, especially using sprayed tungsten carbide instead of chrome-plated corrugating rolls Is the most effective (but the cost is higher, must be considered in conjunction with the business situation). The chrome-plated corrugating roller has a service life of 20 million meters. The number of refurbishments is up to 3 times and the outer diameter is gradually reduced. The service life of sprayed tungsten carbide corrugating roller is doubled, and the 楞 type and the body are not damaged, and the outer diameter is not reduced. Provincial paper and high strength are also advantages.

Corrugated cardboard paste containing device: The glued single-sided corrugated cardboard and board paper fit, usually through the pressure roller (also known as the rider) pressure to achieve. Due to long-term friction with the paper, wear may occur, resulting in inconsistent binding of the entire banner, which in turn causes poor local adhesion of the corrugated cardboard, which is more common at both ends. Solution: Increase the pressure to improve the adhesion at both ends, but the central corrugated fiber may be deformed by pressure; sticking tape on the roller surface at both ends of the pressure roller can also improve the adhesion, but it is difficult to control and may cause the deformation of both ends of the corrugation. The use of pressure bar instead of pressure roller is the best choice. The pressure bar is composed of a set of springs with a length and width of about 12.2cmX and 8.8cm. It does not need to use other power to work. It is parallel and reserved for proper gaps. It is installed at the upper end of the paste machine wheel. On the cardboard contact surface, the contact pressure bar pressure plate is specially designed to have the same curvature as the paste wheel, so that the pressure is stable and the adhesive is uniformly coated. Each contact pressure piece has an independently controlled spring that automatically adjusts for irregular beats to prevent crushing. The hot plate section replaces the gravity roller with a hot plate, so that the layers of the corrugated cardboard are fully attached to each other, and the bonding quality can be greatly improved.

The structure of the hot part: The ordinary tile line, the heating and pressing mechanism of the hot part is composed of a fixed hot plate and gravity pressure device, so the heat transfer is a fixed value. In production, the hot plate temperature is generally controlled by adjusting the steam pressure according to the level, basis weight, and thickness of the base paper. In the production process, when there is a shortage of base paper tension (mainly manifested in insufficient crack length, as mentioned above), lack of material (caused by stress concentration), joints, and broken ends, paper breaks often occur, resulting in deceleration and subsequent connection ( Unless there is a full-automatic sheet feeder, even the machine stops, the speed change breaks the balance of heat transfer, and the fixed hot plate can't adjust the heat. As a result, the corrugated paper in the drying tunnel is excessively heated, causing degumming and warpage. The solution at this time can only remove the corrugated paper from the hot plate by lifting the canvas belt device (when the machine stops for more than 40 seconds, the canvas belt device must be lifted). Although the phenomenon of degumming, warping, etc. is greatly improved, the local degumming phenomenon cannot be avoided and it is accompanied by Creases appear on the cardboard surface, affecting the appearance and causing some difficulties in the printing process. If the hot plate is designed as a hydraulic machine to raise the variable heat heating system, in the production, by adjusting the inclination of the hot plate, a certain gap is created between the hot plate and the corrugated paper, and part of the heat is dissipated from the space, thereby reducing the transfer of the hot plate to the corrugated cardboard. The heat reaches the balance of heat transfer. Or design and install narrow nozzles at the hot plate gap, use a set of air-conditioning valves, open the adjustment valve when the speed decreases, spread the air between the hot plate and the corrugated board to form a corrugated paper The ribbon-like air film that is lifted from the hot plate by the apparatus and the canvas belt achieves the purpose of reducing the excessive heat transfer from the hot plate to the corrugated cardboard.

Fully automatic paper feeder: The use of a fully automatic paper feeder avoids deceleration and shut-down, thus ensuring a stable transfer of heat from the end of the cycle to the end. Production planning arrangements and staff operating levels

General carton companies, due to the wide variety of corrugated board specifications and materials used, involve production planning arrangements.

1) If the small specifications are changed into large specifications immediately after production, the poor adhesion of the large-size corrugated cardboard will occur at both ends. The main reason is: due to paper feeding in the middle, after the completion of small-size corrugated board, the temperature of the middle of the hot plate is lower than that of the two ends. After replacing the large-size corrugated cardboard, the adhesive at both ends may have been gelatinized, and the two ends are Paste the gelatin too much, the result is degumming at both ends. Moreover, according to the principle of thermal expansion and contraction, due to the middle of the paper, the expansion of the middle of the hot plate is less than the end of the hot plate, from the horizontal view of the hot plate, is no longer a plane, but the curved surface, between the corrugated paper and the hot plate The bonding is inconsistent throughout the lateral direction, resulting in a difference in absorbed heat and in the degree of gelatinization of the adhesive, resulting in poor adhesion. The solution is: in the production planning, as much as possible to produce large-size corrugated paper, so that all kinds of corrugated board are heated evenly, consistent gelatinization. If the above schedule cannot be achieved due to the customer's urging of the goods, then at least half an hour shall be taken before the change from the small size to the large size corrugated board, so that the heat on the hot plate can be redistributed.

2) When changing from one type of corrugated board to another type of corrugated board, the requirements for different types of adhesives are different. The solution is: to optimize the combination of corrugated board, the types of base paper are compressed into several types from dozens of kinds, and small-size corrugated cardboard is matched into large-size corrugated cardboard.

3) Statistics show that the main reason for the production of waste defectives on corrugated cardboard lines is due to paper change, and about 70% of them are poorly bonded. The reason is the change of speed or stoppage when changing paper. The solution is: In addition to compressing the type of base paper, properly increase the base paper grade, replace the high- and low-strength base papers with low-quantity and high-strength base papers, and properly increase the base paper grade, replacing low-strength base papers with low-quantity strength base papers. When the batch is large, this method is effective. Because of the same weight of a roll of paper, the lower the amount, the longer the number of meters, not only reduces the inventory and shipping costs, but also reduces the number of paper changes when used.

(d) The level of employee operation is also an important factor.

1) Occasionally, the produced corrugated cardboard forms a regular uncured white line at the bonding site, or has a poor overall adhesion. The former is due to the fact that the corrugated paper has too much force or excessive moisture, or the paper guide plate is trapped in the glue tank, resulting in the application of no adhesive on the paper guide position. Solution: Adjust corrugated paper strength and moisture, appropriately increase the amount of adhesive coating, and adjust the paper guide.

2) Causes of poor overall adhesion: Adhesive quality is not high, or there is insufficient adhesive in the tank, and the amount of coating is too small; the temperature of the adhesive is too high, or the temperature is too low to make the adhesive at the bonding site Can not be gelatinized or the temperature is too high, the molecular structure of the adhesive is destroyed, and the adhesive property is lost; or the gap between the top roller and the top surface of the corrugated file is large and the absorption of the base paper is not good. Solution: If the quality of the adhesive is not high, the quality must be improved; if the adhesive in the tank is insufficient, the amount of adhesive in the tank should be increased to achieve an appropriate coating amount; if the temperature of the adhesive is too high, the temperature should be adjusted: Formulation of rubber, increase the amount of sodium hydroxide to reduce the gelatinization temperature. If the single-sided corrugated board is poorly bonded, there may be no timely discharge of condensate. The hot steam in the corrugated roll releases heat and releases it into condensed water. If it is not discharged in time, it will absorb a part of the heat of the steam and cause the surface temperature of the corrugating roll to be insufficient, resulting in a poor overall adhesion. The solution is to pay close attention to the bonding of single-sided corrugated board and discharge condensed water in time. Similarly, if the double-sided corrugated cardboard is poorly bonded, it may be that the condensate is not discharged in time at the hot plate, and the solution is the same as above.

3) Most of the cases are due to paper change or machine down because the paper change is too slow and the down time is too long. Solution: Proper paper change requires 40 seconds to complete; downtime cannot be exceeded. 1 minute, otherwise the canvas device must be raised. If the gap on the top surface of the corrugating roller is large: it must be adjusted. If the absorption of the base paper is not good, it is necessary to replace the proper absorption of the base paper.

In summary, to solve the problem of poor adhesion of corrugated board, it is necessary not only to have a deeper understanding of the principle of bonding and forming of the board, but also to study the operating characteristics of the board production equipment in order to achieve the best The process plan achieves the best product quality and enables the cardboard production line to operate at high speed, high efficiency and high quality.

(to be continued)