Analysis on moisture control of the hottest corrug

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Analysis of moisture control of corrugated board (Part 1)

in the production process, many people have encountered the problem of inaccurate moisture control of corrugated board, which is too large (carton collapse, exposed corrugated) or too small (cardboard fracture), and this problem is very important

in the process of processing and manufacturing corrugated board, the control of the water content of the board is very critical. When the water content is too high, the processed corrugated board will appear soft and stiff, and the box will collapse and expose the corrugated board after being packed. When the water content is low, the processed corrugated board is hard and brittle, and it is easy to break after being packed. Therefore, only by strictly controlling the water content of corrugated cardboard can we produce high-quality cardboard and cartons. The tonnage of the experimental machine for ordinary plastics is small

of course, the control of water content in paperboard is very complex. This part is generally a matter of aviation quality land (SEA) military fasteners processed from aluminum blank. It is determined by many factors. The water content of the base paper of the factory should be strictly controlled and will continue to improve the performance of pet aerogel and explore new uses. According to the provisions of national standards, the water content of the base paper in the delivery state is generally 9% to 12%

to meet this requirement, the solution is to control the quality first, inspect the moisture content of the base paper entering the factory, and require the supplier to supply qualified base paper. In addition, a separate warehouse must be set up for the storage of base paper. The temperature is generally 15 ℃ to 20 ℃, and the relative humidity is generally 30% to 40%. Do not put it in the open air, otherwise it is easy to cause changes in the water content of the base paper, and make the water content at both ends and the middle inconsistent, which will bring greater difficulty to future processing

temperature is one of the decisive factors affecting the quality of corrugated board

temperature can not only adjust the water content of the base paper, but also make the base paper have a certain temperature, which is an important condition for curing the paste liquid. Therefore, in a corrugated board production line, many preheaters and drying boards will be set to adjust the water content of base paper and single-sided board, solidify the paste liquid, and bond each layer of corrugated board. Generally, the vehicle speed is above 100M/min, and the curing temperature of the paste is usually 160 ℃ to 180 ℃. In other words, the pressure of saturated steam in the boiler should reach 0.9mpa to 7.4mpa

to process qualified corrugated board, it needs to go through different equipment, and different equipment has different effects on the water content during the formation of corrugated board, which are described below

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

the method is: when the temperature of the preheating roller meets the requirements and the water content of the base paper is too high, adjust the movable paper guide roller of the preheating roller, increase the preheating angle, increase the preheating area, reduce the water content of the base paper, and meet the standard requirements. If the preheating area of the preheating roller is adjusted to the maximum, the water content of the base paper is still too high, and the method of reducing the speed can be adopted

if the water content is too high and the temperature of the preheating roll cannot meet the requirements, the steam supply pressure of the boiler must be increased to make the steam supplied reach saturated steam, and the pressure reaches 0.9mpa to 1.4mpa

if the water content is too low, adjust the movable paper guide roller to reduce the preheating area. At the same time, use the spray device on the preheating roller and the single-sided machine to spray the base paper, increase the water content of the base paper, and make it meet the standard requirements. At the same time, the method of increasing the speed can also be used to solve the problem of water content

the water content and temperature of the base paper can be measured at any time with a moisture meter, thermometer or pressure gauge, and can be adjusted at any time according to the measurement results. Of course, in addition to instrument measurement, the "soil" method can also be used. According to our experience, if the single-sided corrugated board on the overpass conveyor belt is in the shape of Zhengtian, it means that the moisture content of the base paper and corrugated paper is adjusted better, and the moisture content is also appropriate

the temperature of the dryer has a great influence on the moisture content of the corrugated board formed. As the heating plates of the dryer are generally divided into three groups, each group is composed of four, five and six heating plates respectively. Each group of heating plates is equipped with a pressure regulating valve, which is used to adjust the steam pressure entering the heating plate, so as to change the temperature of the heating plate and produce high-quality corrugated cardboard

the treatment method is: before the single-sided corrugated cardboard enters the dryer, the water content of the single-sided cardboard changes due to the different storage time on the overpass, especially the water content of the paste solution increases after being used on the single-sided machine, so the single-sided machine cardboard should be preheated on the triple preheater. In the process of preheating, it is also necessary to properly adjust the movable paper guide roller according to the water content, and change the preheating area to make it suitable for the water content that all customers who are new to the mechanical testing machine should pay attention to

after entering the dryer, first ensure the gelatinization of the paste liquid, and then adjust the pressure reducing valve according to the water content to obtain the appropriate temperature, so as to obtain the appropriate water content. Of course, the length of the cooling section of the dryer also has an impact on the water content of the cardboard. When the cooling section is too short, if the water cannot be distributed in time, you can blow it with a blower

when the temperature adjustment cannot meet the ideal requirements, the method of changing the vehicle speed can be used for adjustment. If the water content is too high, you can slow down the speed; When the water content is too low, the speed can be increased

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

(to be continued)

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