First, attention to corrugated board warping in the increasingly finer social division of labor, corrugated board has become the product is sold to the post-processing carton factory, their warpage of corrugated board requirements are more and more intense; In addition, due to social development, carton After the mechanization of the road is becoming more and more high, in order to facilitate the mechanical feeding, to ensure the printing quality, but also require corrugated cardboard flat. So the leveling of corrugated board has become an important indicator to measure the quality of corrugated board.
Internationally, the degree of board warping is usually measured on the basis of US or Japanese standards.
American standards are as follows: (in a one-meter-long corrugated warp camber)
Very slight - less than 5mm;
Slightly - 10mm;
Moderate -15mm;
Severe -20mm;
Very serious - 30mm.
Japanese standards are as follows (same as above):
They are required for cardboard partitions. Generally, the board is allowed to warp at a maximum of 20 mm above 1.2 m width, and 6 mm is the maximum allowable limit for 600 mm and 10 mm to 15 mm for a width of 100 mm.
China's national standard stipulates that the warp of a one-meter-long corrugated cardboard should not exceed 20mm. In contrast, the Japanese standard should be the most reasonable.
The warpage of the corrugated board can be measured by a special warping gauge, or the cardboard can be placed on a platform to measure the chord height of the side arc of the cardboard warped surface.
In general, cardboard has just been out of the double-sided machine because the pressure and moisture have not reached equilibrium, the cardboard is generally relatively flat, with the storage time, cardboard warpage will show up. To determine whether the corrugated board is warped, place the newly produced single sheet of paper in the air for three minutes to see if it is warped. Then check the moisture and temperature of the semi-finished products at each stage of the board product and the production line according to the specific conditions. Analyze the causes and find out the correctness. Warping method.
Second, the main cause of warpage and corrugated board warpage caused by corrugated board warp is the most fundamental reason is due to the corrugated board surface, the paper size changes caused by the difference, this size change is due to the paper inside the cardboard Different moisture content, corrugated board to reach the moisture balance after the double-sided machine, high water content paper release moisture caused by this side of the paper shrink, low water content paper absorbs moisture caused by this side of the paper elongation causes the size difference caused by cardboard warping .
The factors that lead to the above changes in water content can be analyzed from the following factors:
(1) The nature, type and moisture content of the paper in the dough. In general, if the inner paper has a 3% higher moisture content than the top paper, 92% of the paperboard is warped;
If the facial tissue is 3% more moisture than the liner, 75% of the cardboard is warped.
If the moisture distribution in the full width of the base paper is not uniform, S-curvature tends to occur.
In addition, due to the different types of base paper, such as kraft liner paper and tea board paper stretching degree, due to differences in fiber composition, different manufacturing methods vary, if the A grade and C grade two levels of corrugated board combinations It is prone to warping.
If the quantitative weight difference between the paper surface is also very different, it is easy to cause warping.
(2) Ambient temperature and tension The ambient temperature of the workshop also affects the warpage of the cardboard. For example, in the summer, the moisture in the air is higher than in the winter. In this environment, the cardboard easily absorbs the moisture of the air in order to achieve a moisture balance. Variations in the size of the paper cause warping.
In addition, the tension of the paper base paper tray brake, the preheater tension, and the like also cause the cardboard to have a die shrinkage tendency.
(3) Mechanical equipment and operation Due to the difference in operation, the warp is caused by the difference in water content of the paper in the cardboard surface.
(4) Characteristics of the glue and the amount of glue attached. The manufacturing process of the glue is different, and the difference in the amount of glue attached can cause the board to have a difference in water content and warp. Third, the type of corrugated board warping Corrugated board warping types are the following:
(1) Longitudinal warpage (A) Longitudinal warpage (B) Longitudinal warpage (2) Lateral warpage (A) Lateral warpage (B) Lateral warpage 4. Correction of different warping types Although the phenomenon of the corrugated paper right-turning is inevitable due to various reasons, we can control the board warpage within the scope of the standard by adjusting the operation method. These adjustments are carried out under certain conditions, that is, the glue production process is stable and the base paper has been put into use.
(A) lateral warping control lateral upward warping operation;
1, increase the paper preheating angle;
2. Reduce the preheating angle of the paper;
3, to increase the production speed under the premise of guaranteeing the quality of the board;
4. Reduce the amount of glue on a single-sided machine;
5, increase the amount of single-sided cardboard stacking on the flyover (if possible, increase the air blowing device to reduce its moisture content);
6, increase the single-sided cardboard in the triple preheater winding, heating paper to reduce warpage, heating and corrugated adhesion;
7, on the premise of no effect on the quality of the paperboard, increase the amount of glue on the double coater;
8, on the premise of not affecting the adhesion, reduce the temperature of the double-sided machine hot plate;
9. If the core paper is sprayed with steam before adjustment, it should be appropriate or stop spraying;
10. If the paper is the same in the surface, the paper can be exchanged.
11. Spray water mist on the paper when it exits the double-sided machine.
Control the warping operation downwards:
1. Increase the preheated wrap angle of the tissue paper;
2, reduce the paper preheating angle;
3, reduce the production speed under the premise of ensuring the quality of the board;
4, to reduce the amount of single-sided cardboard stacking;
5, reduce the single-sided cardboard in the triple preheater winding;
6, on the premise of not affecting the quality of the paperboard, reduce the amount of glue on the double coater;
7. Increase the tension in the forward direction of single-sided corrugated board machines;
8, face paper exchange;
9, spray paper on the treatment;
10, increase the amount of glue on the single-sided machine;
11, appropriately reduce the speed;
12, slowly increase the temperature of the hot plate of the double-sided machine (by increasing the steam pressure or increasing the number of steam hot plates);
13. Humidify the facing paper when entering the double-sided machine.
(b) Longitudinal Warpage Control Vertical Warpage:
1. Increase the preheated wrap angle of the tissue paper;
2, reduce the paper preheating angle;
3, reduce the production speed under the premise of ensuring the quality of the board;
4, to reduce the amount of single-sided cardboard stacking;
5, reduce the single-sided cardboard in the triple preheater winding;
6, on the premise of not affecting the quality of the paperboard, reduce the amount of glue on the double coater;
7. Increase the tension in the forward direction of single-sided corrugated board machines;
8, face paper exchange;
9, spray paper on the treatment;
10, increase the amount of glue on the single-sided machine;
11, appropriately reduce the speed;
12, slowly increase the temperature of the hot plate of the double-sided machine (by increasing the steam pressure or increasing the number of steam hot plates);
13. Humidify the facing paper when entering the double-sided machine.
(b) Longitudinal Warpage Control Vertical Warpage:
1. The use of base paper with low tension is not affected by the quality of the paperboard;
2. Increase the pressure on the paperboard by the cotton belt to increase the paperboard's force on the hotplate;
3, reduce the preheater brake report group strength;
4. Increase the drag force of single-sided corrugated board on the overpass.
(c) S-type warpage 1. The moisture distribution of the base paper is not uniform, and the moisture content of each section of the paper web can be measured and adjusted by a single-side sprayer;
2, sometimes due to the long-term use of different width of the original paper caused by uneven wear of corrugated roll.
(4) Bi-directional warpage 1, caused by uneven paper moisture, and the adjustment method is the same as that of the above three (1) items;
2. The transverse tension of the belt is uneven, resulting in uneven tension;
3, the original paper frame is not horizontal, the center line of the guide roller, paper frame or preheater is not aligned;
4. The paper guides on the overpass are uneven, unfair or biased;
5. The gluing machine or its rubber roller is not horizontal;
6, the surface of the paper roll is too loose or too tight;
7. There is uneven or diagonal stress in the original paper roll.
Two-way warpage adjustment is relatively complex, generally it is first adjusted to one-way (horizontal or longitudinal) warpage and then adjusted accordingly.
Fifth, warpage cardboard remedies 1, will warp cardboard positive and negative pressure;
2, the warpage cardboard storage environment for humidification;
3. Apply mechanical force.
In short, the warpage of corrugated paperboard is caused by many reasons. To reduce the warpage phenomenon, it is only necessary to analyze the reasons in detail according to specific conditions and make careful adjustments to find out the correct remedy. (Author: Hefei Meiling Packing Products Co., Xu Baoqing)
Internationally, the degree of board warping is usually measured on the basis of US or Japanese standards.
American standards are as follows: (in a one-meter-long corrugated warp camber)
Very slight - less than 5mm;
Slightly - 10mm;
Moderate -15mm;
Severe -20mm;
Very serious - 30mm.
Japanese standards are as follows (same as above):
They are required for cardboard partitions. Generally, the board is allowed to warp at a maximum of 20 mm above 1.2 m width, and 6 mm is the maximum allowable limit for 600 mm and 10 mm to 15 mm for a width of 100 mm.
China's national standard stipulates that the warp of a one-meter-long corrugated cardboard should not exceed 20mm. In contrast, the Japanese standard should be the most reasonable.
The warpage of the corrugated board can be measured by a special warping gauge, or the cardboard can be placed on a platform to measure the chord height of the side arc of the cardboard warped surface.
In general, cardboard has just been out of the double-sided machine because the pressure and moisture have not reached equilibrium, the cardboard is generally relatively flat, with the storage time, cardboard warpage will show up. To determine whether the corrugated board is warped, place the newly produced single sheet of paper in the air for three minutes to see if it is warped. Then check the moisture and temperature of the semi-finished products at each stage of the board product and the production line according to the specific conditions. Analyze the causes and find out the correctness. Warping method.
Second, the main cause of warpage and corrugated board warpage caused by corrugated board warp is the most fundamental reason is due to the corrugated board surface, the paper size changes caused by the difference, this size change is due to the paper inside the cardboard Different moisture content, corrugated board to reach the moisture balance after the double-sided machine, high water content paper release moisture caused by this side of the paper shrink, low water content paper absorbs moisture caused by this side of the paper elongation causes the size difference caused by cardboard warping .
The factors that lead to the above changes in water content can be analyzed from the following factors:
(1) The nature, type and moisture content of the paper in the dough. In general, if the inner paper has a 3% higher moisture content than the top paper, 92% of the paperboard is warped;
If the facial tissue is 3% more moisture than the liner, 75% of the cardboard is warped.
If the moisture distribution in the full width of the base paper is not uniform, S-curvature tends to occur.
In addition, due to the different types of base paper, such as kraft liner paper and tea board paper stretching degree, due to differences in fiber composition, different manufacturing methods vary, if the A grade and C grade two levels of corrugated board combinations It is prone to warping.
If the quantitative weight difference between the paper surface is also very different, it is easy to cause warping.
(2) Ambient temperature and tension The ambient temperature of the workshop also affects the warpage of the cardboard. For example, in the summer, the moisture in the air is higher than in the winter. In this environment, the cardboard easily absorbs the moisture of the air in order to achieve a moisture balance. Variations in the size of the paper cause warping.
In addition, the tension of the paper base paper tray brake, the preheater tension, and the like also cause the cardboard to have a die shrinkage tendency.
(3) Mechanical equipment and operation Due to the difference in operation, the warp is caused by the difference in water content of the paper in the cardboard surface.
(4) Characteristics of the glue and the amount of glue attached. The manufacturing process of the glue is different, and the difference in the amount of glue attached can cause the board to have a difference in water content and warp. Third, the type of corrugated board warping Corrugated board warping types are the following:
(1) Longitudinal warpage (A) Longitudinal warpage (B) Longitudinal warpage (2) Lateral warpage (A) Lateral warpage (B) Lateral warpage 4. Correction of different warping types Although the phenomenon of the corrugated paper right-turning is inevitable due to various reasons, we can control the board warpage within the scope of the standard by adjusting the operation method. These adjustments are carried out under certain conditions, that is, the glue production process is stable and the base paper has been put into use.
(A) lateral warping control lateral upward warping operation;
1, increase the paper preheating angle;
2. Reduce the preheating angle of the paper;
3, to increase the production speed under the premise of guaranteeing the quality of the board;
4. Reduce the amount of glue on a single-sided machine;
5, increase the amount of single-sided cardboard stacking on the flyover (if possible, increase the air blowing device to reduce its moisture content);
6, increase the single-sided cardboard in the triple preheater winding, heating paper to reduce warpage, heating and corrugated adhesion;
7, on the premise of no effect on the quality of the paperboard, increase the amount of glue on the double coater;
8, on the premise of not affecting the adhesion, reduce the temperature of the double-sided machine hot plate;
9. If the core paper is sprayed with steam before adjustment, it should be appropriate or stop spraying;
10. If the paper is the same in the surface, the paper can be exchanged.
11. Spray water mist on the paper when it exits the double-sided machine.
Control the warping operation downwards:
1. Increase the preheated wrap angle of the tissue paper;
2, reduce the paper preheating angle;
3, reduce the production speed under the premise of ensuring the quality of the board;
4, to reduce the amount of single-sided cardboard stacking;
5, reduce the single-sided cardboard in the triple preheater winding;
6, on the premise of not affecting the quality of the paperboard, reduce the amount of glue on the double coater;
7. Increase the tension in the forward direction of single-sided corrugated board machines;
8, face paper exchange;
9, spray paper on the treatment;
10, increase the amount of glue on the single-sided machine;
11, appropriately reduce the speed;
12, slowly increase the temperature of the hot plate of the double-sided machine (by increasing the steam pressure or increasing the number of steam hot plates);
13. Humidify the facing paper when entering the double-sided machine.
(b) Longitudinal Warpage Control Vertical Warpage:
1. Increase the preheated wrap angle of the tissue paper;
2, reduce the paper preheating angle;
3, reduce the production speed under the premise of ensuring the quality of the board;
4, to reduce the amount of single-sided cardboard stacking;
5, reduce the single-sided cardboard in the triple preheater winding;
6, on the premise of not affecting the quality of the paperboard, reduce the amount of glue on the double coater;
7. Increase the tension in the forward direction of single-sided corrugated board machines;
8, face paper exchange;
9, spray paper on the treatment;
10, increase the amount of glue on the single-sided machine;
11, appropriately reduce the speed;
12, slowly increase the temperature of the hot plate of the double-sided machine (by increasing the steam pressure or increasing the number of steam hot plates);
13. Humidify the facing paper when entering the double-sided machine.
(b) Longitudinal Warpage Control Vertical Warpage:
1. The use of base paper with low tension is not affected by the quality of the paperboard;
2. Increase the pressure on the paperboard by the cotton belt to increase the paperboard's force on the hotplate;
3, reduce the preheater brake report group strength;
4. Increase the drag force of single-sided corrugated board on the overpass.
(c) S-type warpage 1. The moisture distribution of the base paper is not uniform, and the moisture content of each section of the paper web can be measured and adjusted by a single-side sprayer;
2, sometimes due to the long-term use of different width of the original paper caused by uneven wear of corrugated roll.
(4) Bi-directional warpage 1, caused by uneven paper moisture, and the adjustment method is the same as that of the above three (1) items;
2. The transverse tension of the belt is uneven, resulting in uneven tension;
3, the original paper frame is not horizontal, the center line of the guide roller, paper frame or preheater is not aligned;
4. The paper guides on the overpass are uneven, unfair or biased;
5. The gluing machine or its rubber roller is not horizontal;
6, the surface of the paper roll is too loose or too tight;
7. There is uneven or diagonal stress in the original paper roll.
Two-way warpage adjustment is relatively complex, generally it is first adjusted to one-way (horizontal or longitudinal) warpage and then adjusted accordingly.
Fifth, warpage cardboard remedies 1, will warp cardboard positive and negative pressure;
2, the warpage cardboard storage environment for humidification;
3. Apply mechanical force.
In short, the warpage of corrugated paperboard is caused by many reasons. To reduce the warpage phenomenon, it is only necessary to analyze the reasons in detail according to specific conditions and make careful adjustments to find out the correct remedy. (Author: Hefei Meiling Packing Products Co., Xu Baoqing)
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