Here again, the paper moisture problem is repeated. The warpage is caused by the unbalanced water content of the two-sided liner paper of the corrugated cardboard. Regarding the influence of the raw paper moisture used, CID conducted a large-scale experiment, ie, the raw paper of different moisture was used as the paper of single-sided corrugated cardboard and the paper of corrugated cardboard to investigate the relationship between moisture and warpage of raw paper.
When the liner paper using a single-faced corrugated cardboard has 3% more paper than the face paper of a corrugated cardboard, 92% of the roll paper is warped. When the surface paper moisture of the corrugated cardboard is 3% larger than that of the single corrugated cardboard, 75% becomes a warp.
Therefore, when selecting the base paper, the moisture fluctuation of the noodle paper (noodle paper of single-sided machine and noodle paper of corrugated cardboard) must be kept within 3%. As a solution to warpage, besides the moisture of the base paper, note also on the corrugated board machine:
(1) Increase the wrap angle between the preheater and the preprocessor at the single-faced corrugator.
(2) Minimize the amount of glue on a single-faced corrugator.
(3) Reduce the amount of single-sided corrugated cardboard stacked on the bridge and keep the speed of the single-faced corrugator and the double-sided machine as consistent as possible.
(4) Minimize the amount of glue on the corrugated board and then at the paste machine.
The above four items are all designed to solve the problem of cardboard upturning, so as to reduce the excessive water setting when the single-faced corrugated cardboard enters the double-sided machine. At the same time, in order to increase the water content of corrugated cardboard as much as possible, attention should be paid to:
(1) Reducing the face paper and preheating the wrap angle on the machine.
(2) Properly stretch the base paper.
(3) Reduce the heating temperature of the dual engine or increase the speed.
In addition to this, we must also pay attention to:
(1) Single-faced corrugated cardboard with uneven corrugations.
(2) The viscosity and concentration of the gum are appropriate.
(3) The single-sided corrugated board entering the double-sided machine cannot be fanned.
(4) The pressure of the pressure roller on the double-sided machine is moderate, and the lateral pressure is even.
In the above, the cause of upward warping and downward warpage of the paperboard and the solution to upward warpage have been introduced, and the solution to the warpage of the lower warp has not been difficult to find from the above description.
2. S-warped warpage and warpage are simply warped, S- warpage and diagonal warpage described later, is a trace of trouble. When this kind of warpage occurs, it can be piled up by flipping 180 degrees in groups of 10-20 sheets at the production line. At the same time, when such warpage is serious, in addition to the above-mentioned method of accumulation, a heavy object must be used to flatten the warpage. Otherwise, it will cause obstacles in the subsequent box-making process.
The cause of S-warping is;
(1) The horizontal wet stripe on the hang-up roll.
(2) Large amount of water is left on the roll of the liner.
(3) The heating temperature of the double-sided machine is not uniform.
The upper spot on the ordinate indicates the percentage of moisture in the paper, and the lower half indicates the warpage of the paperboard produced. The abscissa indicates the web width width (inches). If the wet spot is on the operation side of the corrugating machine, a warp of warpage of 0.8 occurs on the operation side. If the web is used in reverse, the operating side decreases by 0.3 from the warpage before flipping to 0.8; but the driving side changes from 0.2 to 1.0, which confirms the wet spot on the web banner to the web. The warpage of the cardboard part is influential.
The relationship between the width of the wet spot in the direction of the noodle base paper banner and the degree of excess moisture is related to the warpage. CID uses the following figure to show the relationship between them. That is, the relationship between the width of the wet spot and the average moisture content of the base paper and the percentage of the excess moisture when the product of the percentage of excess moisture reaches 40 or more can reach 1 or more, and unacceptable warping occurs (for example, the width of the wet spot is 10 in When this part contains 4% of the average moisture content, uncontrollable warpage can occur.
The main key to overcome the S-type warping from the above three items is that the moisture content of the base paper should be even, and then the control temperature of the double-sided machine should be even.
3. Warpage in the length direction The warpage of adult corrugated cardboard has no relation with the base paper. This is due to the tension adjustment in the production process of corrugated cardboard. That is, the tension of the corrugated cardboard facing paper sheet and the three-layer preheating machine is too tight and the tension difference between the corrugated cardboard and the single-faced corrugated cardboard is too large. At the same time, the tension on the corrugated cardboard is too tight, which is one of the reasons for the length error in the paper cutter. The solution is to reduce the difference in tension between single-sided corrugated cardboard and corrugated cardboard on paper.
4. Diagonal Warpage Diagonal Warpage is the warp produced by the combination of longitudinal and lateral warping. The reason for this is that the single-sided corrugated paperboard on the bridge is overloaded, the tension on one-sided corrugated board is too large (tension is the cause of longitudinal warpage), and the other is upturned, downturned, or warped (as described above. It is due to the fact that the difference in the moisture content of the corrugated board has destroyed the balance of telescopicity). Therefore, in order to solve the diagonal warpage, it is necessary to comprehensively consider the above-mentioned various situations, and eliminate the above-mentioned unfavorable conditions one by one during operation, and observe while operating. For example, the water content of the cardboard can be balanced by spraying water on the single-faced corrugated cardboard or tissue paper; the tension of the paper can be adjusted by adjusting the brake pad tension, the angle of the preheating machine can be adjusted, and the angle of the pretreatment machine can be adjusted; Means control the tension of the board; the speed of the corrugated board production line can be controlled to operate under stable conditions, and the amount of accumulation on the bridge frame can be reasonably reduced without overloading.
After analyzing the warpage factors of corrugated cardboard, especially through the analysis of the verification results of cardboard warpage by foreign institutions, we have a comprehensive understanding of warping, warping types and solutions of paperboard. It is believed that it will play an active guiding role in improving the quality of production board. (Zheng Zhengpei, Carton Machinery Branch of Shanghai Electric Group Printing & Packaging Co., Ltd.)
When the liner paper using a single-faced corrugated cardboard has 3% more paper than the face paper of a corrugated cardboard, 92% of the roll paper is warped. When the surface paper moisture of the corrugated cardboard is 3% larger than that of the single corrugated cardboard, 75% becomes a warp.
Therefore, when selecting the base paper, the moisture fluctuation of the noodle paper (noodle paper of single-sided machine and noodle paper of corrugated cardboard) must be kept within 3%. As a solution to warpage, besides the moisture of the base paper, note also on the corrugated board machine:
(1) Increase the wrap angle between the preheater and the preprocessor at the single-faced corrugator.
(2) Minimize the amount of glue on a single-faced corrugator.
(3) Reduce the amount of single-sided corrugated cardboard stacked on the bridge and keep the speed of the single-faced corrugator and the double-sided machine as consistent as possible.
(4) Minimize the amount of glue on the corrugated board and then at the paste machine.
The above four items are all designed to solve the problem of cardboard upturning, so as to reduce the excessive water setting when the single-faced corrugated cardboard enters the double-sided machine. At the same time, in order to increase the water content of corrugated cardboard as much as possible, attention should be paid to:
(1) Reducing the face paper and preheating the wrap angle on the machine.
(2) Properly stretch the base paper.
(3) Reduce the heating temperature of the dual engine or increase the speed.
In addition to this, we must also pay attention to:
(1) Single-faced corrugated cardboard with uneven corrugations.
(2) The viscosity and concentration of the gum are appropriate.
(3) The single-sided corrugated board entering the double-sided machine cannot be fanned.
(4) The pressure of the pressure roller on the double-sided machine is moderate, and the lateral pressure is even.
In the above, the cause of upward warping and downward warpage of the paperboard and the solution to upward warpage have been introduced, and the solution to the warpage of the lower warp has not been difficult to find from the above description.
2. S-warped warpage and warpage are simply warped, S- warpage and diagonal warpage described later, is a trace of trouble. When this kind of warpage occurs, it can be piled up by flipping 180 degrees in groups of 10-20 sheets at the production line. At the same time, when such warpage is serious, in addition to the above-mentioned method of accumulation, a heavy object must be used to flatten the warpage. Otherwise, it will cause obstacles in the subsequent box-making process.
The cause of S-warping is;
(1) The horizontal wet stripe on the hang-up roll.
(2) Large amount of water is left on the roll of the liner.
(3) The heating temperature of the double-sided machine is not uniform.
The upper spot on the ordinate indicates the percentage of moisture in the paper, and the lower half indicates the warpage of the paperboard produced. The abscissa indicates the web width width (inches). If the wet spot is on the operation side of the corrugating machine, a warp of warpage of 0.8 occurs on the operation side. If the web is used in reverse, the operating side decreases by 0.3 from the warpage before flipping to 0.8; but the driving side changes from 0.2 to 1.0, which confirms the wet spot on the web banner to the web. The warpage of the cardboard part is influential.
The relationship between the width of the wet spot in the direction of the noodle base paper banner and the degree of excess moisture is related to the warpage. CID uses the following figure to show the relationship between them. That is, the relationship between the width of the wet spot and the average moisture content of the base paper and the percentage of the excess moisture when the product of the percentage of excess moisture reaches 40 or more can reach 1 or more, and unacceptable warping occurs (for example, the width of the wet spot is 10 in When this part contains 4% of the average moisture content, uncontrollable warpage can occur.
The main key to overcome the S-type warping from the above three items is that the moisture content of the base paper should be even, and then the control temperature of the double-sided machine should be even.
3. Warpage in the length direction The warpage of adult corrugated cardboard has no relation with the base paper. This is due to the tension adjustment in the production process of corrugated cardboard. That is, the tension of the corrugated cardboard facing paper sheet and the three-layer preheating machine is too tight and the tension difference between the corrugated cardboard and the single-faced corrugated cardboard is too large. At the same time, the tension on the corrugated cardboard is too tight, which is one of the reasons for the length error in the paper cutter. The solution is to reduce the difference in tension between single-sided corrugated cardboard and corrugated cardboard on paper.
4. Diagonal Warpage Diagonal Warpage is the warp produced by the combination of longitudinal and lateral warping. The reason for this is that the single-sided corrugated paperboard on the bridge is overloaded, the tension on one-sided corrugated board is too large (tension is the cause of longitudinal warpage), and the other is upturned, downturned, or warped (as described above. It is due to the fact that the difference in the moisture content of the corrugated board has destroyed the balance of telescopicity). Therefore, in order to solve the diagonal warpage, it is necessary to comprehensively consider the above-mentioned various situations, and eliminate the above-mentioned unfavorable conditions one by one during operation, and observe while operating. For example, the water content of the cardboard can be balanced by spraying water on the single-faced corrugated cardboard or tissue paper; the tension of the paper can be adjusted by adjusting the brake pad tension, the angle of the preheating machine can be adjusted, and the angle of the pretreatment machine can be adjusted; Means control the tension of the board; the speed of the corrugated board production line can be controlled to operate under stable conditions, and the amount of accumulation on the bridge frame can be reasonably reduced without overloading.
After analyzing the warpage factors of corrugated cardboard, especially through the analysis of the verification results of cardboard warpage by foreign institutions, we have a comprehensive understanding of warping, warping types and solutions of paperboard. It is believed that it will play an active guiding role in improving the quality of production board. (Zheng Zhengpei, Carton Machinery Branch of Shanghai Electric Group Printing & Packaging Co., Ltd.)
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