The hottest rainy season comes when corrugated is

When the rainy season comes and the corrugated is wet and soft, it is crucial to do a good job in the temperature control of the corrugated line

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core tip: it is another rainy season, and it is wet everywhere. At this time, the people who are engaged in the production and printing of corrugated board are the most painful. The wet and soft paperboard not only reduces the compression resistance of the carton by half, but also easily causes creases and collapse pits, and causes the bottom of the printing

[China Packaging News] it is another rainy season, and it is wet everywhere. At this time, the most painful thing is the people engaged in corrugated board production and printing. The wet and soft paperboard not only reduces the compression resistance of the carton by half, but also easily causes creases and collapse pits, and causes the bottom of the printing

to solve the problem of wet and soft corrugated board, in addition to the most direct and effective method of replacing high-strength corrugated paper with surface water absorption less than 40 g/m2 (60s), strengthening the control of temperature in the process of producing corrugated board also has obvious results. By controlling the temperature, the water content of the corrugated base paper can be adjusted, and the curing time of the paste liquid can be controlled, so as to achieve the purpose of controlling the bonding speed and firmness of the corrugated paper. Therefore, the temperature control is a very important link in the corrugated paper production process, and carelessness is not allowed

1. Temperature control of single-sided machine

according to the analysis of the tension in the forming process of corrugated board, it is the best that the water content of the base paper entering the single-sided machine is 9% ~ 12% during corrugated forming. According to this principle, we must make full use of the preheating roller on the single-sided machine and the preheating machine and spray device before and after the single-sided machine to adjust the water content of the base paper

if the plasticization of polymer in the base paper is caused by two conditions: the reduction of shear strength and the increase of contact area when high molecular materials contact other surfaces, when the water content is too high, the movable paper guide roller of the preheating roller can be adjusted appropriately after the temperature of the preheating roller meets the requirements, and the preheating wrap angle of the base paper can be increased by 2 Wear resistance of connecting shaft: This is also an important experiment. Increasing the preheating area can reduce the water content of base paper to a certain extent. If the preheating area of the preheating roller is adjusted to the maximum and the water content of the base paper is still too high, the method of reducing the speed should be adopted

when the moisture content of the base paper is too high, sometimes the temperature of the pre adjusted preheating roller will be reduced, so that the preheating requirements can not be met. p>

if the water content of the base paper is too low, the movable paper guide roller should be adjusted accordingly to reduce the preheating area. At the same time, the preheating roller and the spray device on the single-sided machine should be used to spray the base paper to increase the water content of the base paper and make it meet the standard requirements. In addition, the problem of low water content can also be solved to a certain extent by appropriately increasing the speed so as to reduce the contact time between the base paper and the preheating roller in a disguised form

the moisture content and temperature of the base paper should be measured at any time with a moisture meter, thermometer or pressure gauge, and adjusted according to the measurement results. Some materials mentioned some soil methods, such as observing the single-sided corrugated board on the conveyor belt of the overpass. If it is orthographic, it can be considered that the moisture adjustment of the base paper is better and the moisture content is also more appropriate; For another example, when there is no thermometer, spit a mouthful of saliva on the preheater. If saliva can jump on the preheater, it means that the temperature has exceeded 150 ℃, and production can be carried out, etc. However, for the purpose of scientific management of production and ensuring product quality, these indigenous methods should be used less. As a formal enterprise, we should reduce the influence of human factors, comply with scientific and accurate data, and manage production

2. Temperature control of the dryer

the temperature of the dryer directly affects the water content of the final formed corrugated board. The heating plates of the dryer are generally three groups, each group is composed of four, five and six heating plates respectively. Each group of heating plates of the dryer heated by steam is equipped with a pressure regulating valve to adjust the steam pressure entering the heating plate, so as to change the temperature of the heating plate and ensure the production of high-quality corrugated cardboard. Among them, we need to pay attention to the following details

before entering the dryer, the water content will change due to the different storage time of single-sided corrugated board on the overpass. In addition, the water content of the paste liquid on the single-sided machine will also change after a period of use, which will lead to the change of the water content of the single-sided corrugated board. Therefore, before final compounding, it is necessary to preheat single-sided corrugated board twice. This preheating process should also be properly adjusted according to the water content, that is, by adjusting the movable paper guide roller and changing the preheating area, the purpose of adjusting the water content of corrugated board can be achieved

the purpose of drying is to ensure the solidification of paste liquid and adjust the water content of corrugated board at the same time. The two cannot be neglected. Therefore, the pressure reducing valve should be adjusted at any time according to the water content of single-sided corrugated board to make the dryer reach the appropriate temperature, which can not only ensure the curing of paste liquid, but also ensure the moderate water content of the final formed corrugated board. In addition, the length of the cooling section of the dryer also has a certain impact on the moisture content of the paperboard. The cooling section is too short, and the water cannot volatilize in time. At this time, it is necessary to increase the local air supply to achieve the purpose of drying

if the normal temperature adjustment cannot reach the ideal condition, you can try to adjust it by changing the vehicle speed. That is, slow down when the water content is too high, and increase the speed when the water content is too low

when the dryer is working, it cannot stop until it is absolutely necessary. If the front single-sided machine needs to change the paper roll, the speed of the sports car can be faster before changing the roll, and more single-sided paperboard can be accumulated on the overpass. After receiving the paper change notice, the dryer can run at a reduced speed. If the dryer is shut down, the moisture in the cardboard on the dryer will evaporate completely, causing all the cardboard to be discarded

3. The influence of drainage device on temperature

in addition to the pressure of steam supplied by the boiler, the drainage device of the steam pipeline system is also very important. This is because when the base paper and single-sided paperboard pass through each preheater, they will take away a lot of heat, so that part of the saturated steam condenses into liquid water. This part of condensate must be discharged in time, otherwise it will affect the heating effect of the preheater

in daily work, if the temperature of the preheating roller using the steam spinning head is low or the temperature difference between the two ends is more than 5 ℃, it indicates that the straw is damaged or the installation position is wrong, and it must be disassembled for maintenance. Generally speaking, the flow index of the steam trap should be 2 ~ 3 times that of the condensate. If the drainage is not enough, the steam trap should be replaced. In addition, in daily operation and production, we should form a good habit, check the drain outlet of the steam trap every week, and clean it in time in case of blockage

during the startup and operation of the corrugated paper production line, the above parts should be checked and adjusted at any time. Only in this way can we ensure the production of qualified products