12 important indicators of paper bags of Kraft paper production line operation
Jan 14, 2022
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12 important indicators of paper bags of Kraft paper production line operation
In the process management of carton enterprises, standardization is one of the important tools. It is very important and necessary for carton enterprises to pay attention to and strengthen process standardization. Process standardization is an important step for carton enterprises to achieve standardization, and the standardized control of each process link in the carton production process is an important part of process standardization.
Twelve important indicators of the operation of the paper bags of Kraft paper production line, how is your factory doing?
Adhesive index
The viscosity and solid content of the adhesive for paper bags of Kraft paper should be adjusted according to the season.
Usually, at low temperature and low humidity (winter), the viscosity of the adhesive for single-corrugated cardboard is 17-21s (coating 4 cups, the same below), and the solid content is 17%-19%; the viscosity of the adhesive for three-corrugated cardboard is 40- 60s, the solid content is 18% to 20%.
At high temperature and high humidity (summer), the viscosity of the adhesive for single-corrugated cardboard is 20-25s, and the solid content is 19%-22%; the viscosity of the adhesive for three-corrugated cardboard is 55-90s, and the solid content is 21%-25%. %.
In addition, it should be ensured that the sticking length of the adhesive (dip a little adhesive on the thumb, stick with the index finger, slowly pull the two fingers apart until the adhesive breaks) is 15-20mm.
Base paper index
(1) The moisture content of the base paper. The moisture content of the base paper should be 6% to 8%, which is the most favorable for the bonding and corrugated forming effect of corrugated cardboard. The difference in moisture content between the three base papers and the left, middle and right sides of each base paper shall not exceed 3%.
(2) Base paper production time. The production dates of the three kinds of base paper must be similar before they can be used on the machine.
(3) The folding endurance of the base paper. The base paper should be produced in a low temperature and low humidity environment. In order to prevent the quality problem of the carton from bursting due to the low folding endurance, the base paper must be folded more than 50 times.
(4) Strength of base paper. The strength of the base paper is determined according to the customer's compressive requirements for the corrugated box used and the production process of the carton. If the compressive strength of a certain box-shaped carton is required to reach 1500N, through analysis and calculation, if the offset printing carton is used, the base paper should be high-strength grade A, the basis weight should be 120g/m2, and the ring pressure index should be greater than 7N・m/g; if the watermark is used Or the pre-printing process to print the carton, the base paper should be high-strength grade A, the basis weight should be 110g/m2, and the ring pressure index should be greater than 6N·m/g.
The choice of the strength of the base paper is more complicated, and it must be determined after analysis, calculation and test according to the relevant technology. Once determined, for this type of box, the base paper must not be replaced, and the base paper with the specified strength must be selected during production.
Base paper tension adjustment
The strength of the base paper should be adjusted according to the longitudinal bending degree of the corrugated cardboard and the usage.
When the corrugated cardboard is bent in the longitudinal direction of a certain base paper, the tension of the base paper should be released. The tension control of the base paper core and the outside of the roll is different. The tension parameters of the base paper must be reduced at the core to prevent the paper from breaking. Excessive strength of the base paper can easily cause quality problems such as paper breakage, longitudinal bending of corrugated cardboard, and unsatisfactory corrugated forming effect. On the contrary, it is easy to cause corrugated cardboard to blister and warp.
Preheat wrap angle
The surface temperature of the preheating drum must reach above 100℃, and the temperature of the hot pressing plate must reach above 150℃.
The size of the preheat wrapping angle is proportional to the contact area of the base paper on the preheating roller and the moisture content of the base paper. During the production process, the preheat wrapping angle can be increased or decreased according to the horizontal bending degree of the paper bags of Kraft paper. For example, when the single corrugated cardboard and the three corrugated cardboard are bent in the transverse direction, in which direction the base paper is bent, the preheating wrapping angle of the base paper is increased, and the preheating wrapping angle of the other base paper is reduced.
Stack adjustment
Although stacking paper at the bridge helps to volatilize the moisture of corrugated cardboard, excessive stacking of paper will cause the corrugated cardboard to appear washboard and bending. Therefore, it is necessary to reasonably control the stacking amount according to the effect of the board.
Dust removal system
When producing three-corrugated cardboard, the cleanliness of the cardboard should be ensured. The dust removal system of the corrugated cardboard production line, the use of brushes to remove dust, and the opening of the suction device to reduce the printing quality problems caused by paper wool in the subsequent printing process.
Vapor pressure and hot plate control
Ensure that the minimum vapor pressure is greater than 7kg and the internal temperature of the hot-pressing plate reaches 150°C before starting production. In actual production, the hot-pressing board is reasonably adjusted according to the bending degree and speed of the paper bags of Kraft paper.
When the corrugated cardboard is bent laterally in the direction of the box board, the latter group of hot-pressing boards should be lifted to reduce the internal temperature of the hot-pressing board under the premise of ensuring the gelatinization of the glue. When producing corrugated cardboard with a longitudinal dimension less than 600mm, the machine speed should be reduced by 30% to 40%, the latter group of hot pressing plate steam pressure devices should be closed or lifted, and the hot pressing plate should be lifted to dissipate heat.
For pre-printed cardboard, in order to achieve no quality problems at 150°C, the pre-printed surface paper should be made of high temperature resistant varnish. The platen temperature was lowered to 130°C for reproduction.
According to the size of corrugated cardboard production scheduling
After the production of corrugated cardboard with larger size, it is not allowed to produce corrugated cardboard with smaller size immediately. For example, after our factory normally produces corrugated cardboard with a vertical size of 1020mm, if the corrugated cardboard with a small vertical size (such as less than 600mm) is replaced immediately, the internal temperature of the hot-pressing board cannot be greatly reduced in a short time after the shutdown. Serious bending deformation of corrugated cardboard. Therefore, the production of corrugated cardboard with a longitudinal dimension less than 600mm should be placed at the beginning of single-day production.
After the production of corrugated cardboard with a smaller size is completed, it is not allowed to produce corrugated cardboard with a larger size immediately. This is because the production of corrugated cardboard with a small size is carried out at low speed and low temperature. Once the corrugated cardboard with a larger size is replaced immediately, the temperature of the hot pressing board cannot be quickly raised to the set temperature, the glue is not gelatinized enough, and the moisture content Slow dissipation will make the cardboard stiffness low, and the corrugated has no stiffness. Therefore, it can only be produced after the temperature of the hot pressing plate reaches the standard range.
pressure regulation
The first is the pressure adjustment between the upper and lower corrugating rollers and the pressure rollers, which directly affects the corrugated forming effect. If the pressure is too large, the corrugated corrugated will be fried or crushed; if the pressure is uneven, the thickness of the corrugated cardboard will be uneven and the amount of glue applied will be uneven; if the pressure is too small, the corrugated forming effect will be worse.
The second is the adjustment of the glue gap. The gap value is inversely proportional to the pressure. If the gap value is too small, that is, the pressure is too large, the stiffness of the cardboard will decrease, the flute height will decrease, and the compressive strength of the carton will decrease; if the gap value is too large, that is, the pressure will be too small, which will affect the bonding effect of the cardboard , resulting in poor adhesion. When producing single-corrugated cardboard, the sizing gap is 3.2 to 3.6mm; when producing three-corrugated cardboard, the sizing gap is 2.6mm for single-corrugated cardboard and 2.2mm for triple-corrugated cardboard. The gap value between them should be guaranteed to be 3.0mm.
speed control
The vehicle speed has a great influence on the flatness of the corrugated cardboard. Under the premise that the vapor pressure is about 7kg and the temperature of the hot pressing plate is about 150℃, when the longitudinal dimension of the corrugated cardboard is greater than 600mm, the vehicle speed should be controlled to 140 ~ 160m/min; When the longitudinal dimension is less than 600mm, the vehicle speed should be controlled at 90-100m/min.
Internal cleaning of the platen
When the paper wool, paper scraps or glue solid substances and other impurities adhere to the surface of the hot pressing board or the surface of the adhesive tape, it will cause scratches and ravines on the surface of the paper bags of Kraft paper. At this time, the machine must be stopped for cleaning, otherwise the subsequent printing process It is easy to appear the quality problem of no ink.
collect paper
Single-corrugated cardboard and triple-corrugated cardboard must be stacked or received neatly and in accurate quantity.
20 sheets of single corrugated cardboard are stacked upside down. 500 sheets of three-corrugated cardboard are one set. When the bending arc is greater than 1% of the width of the cardboard, each cardboard is also stacked with 20 front and back sides to avoid the cardboard being continuously bent and deformed during the storage process.