Process control and standardization of corrugated board production lines
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In the process management of carton enterprises, standardization is one of the important tools. It is very important and necessary for carton enterprises to attach importance to and strengthen process standardization. Process standardization is an important step in the standardization of carton enterprises, and the standardized control of each process link in the carton production process is an important part of process standardization.
As one of the key links in the production of carton, corrugated board production often has problems such as disorderly production schedule, frequent quality accidents, and low efficiency, which greatly affects the efficiency and customer satisfaction of carton enterprises. In order to avoid such problems, carton enterprises can formulate uniform standards for process factors, process parameters, and process documents according to the production characteristics of corrugated board production lines. Its role is: First, it is of great significance to improve the technical level of the process, ensure the stability of product quality, improve production efficiency, reduce labor intensity, improve the utilization rate of raw materials, and strengthen process management. Second, to make employees "documents, operation, and intentions" The standardized documents in the mind are put into actual operation, standardizing and guiding operations, thus simplifying production, organizing production, directing production and guiding operations; third, operating the employees through the management method of "changing thinking with behavior" Constraint, eliminate the behavior of capricious operation, escort the next process and carton quality, so that employees form the overall situation of the overall process considerations. Here, the paper will introduce the process control and standardization of corrugated board production line according to the actual situation of the author's enterprise.
Process and control points for corrugated board production lines
Control Point 1: Accurately verify the original paper information on the voucher, including the width, weight, manufacturer and special requirements of the base paper.
Control point 2: Glue is strictly in accordance with the formula of rubber preparation, and the adhesive index should be qualified.
Control point 3: Ensure that the size is accurate.
Control point 4: The amount of glue applied, the temperature inside the drying belt, and the tension value are executed in accordance with the "Technical Standards" of the corrugated board production line established by the company.
Control point 5: Cardboard flatness, neatness, corrugated forming effect, high height, and adhesion strength are in line with the quality standard of the chopped board production line established by the company.
Control Point 6: Adjust the process specifications to be within the scope of the Process Standards.
Process standardization of corrugated board production line
1. Adhesive index
The viscosity and solid content of the adhesive for corrugated board should be adjusted according to the season. Generally, when the temperature is low and low humidity (winter), the adhesive viscosity of the single corrugated board is 17-21s (coating 4 cups, the same below), the solid content is 17%-19%; the viscosity of the adhesive for the three corrugated board is 40~ 60s, solid content is 18% to 20%. In high temperature and high humidity (summer), the viscosity of adhesive for single corrugated board is 20~25s, the solid content is 19%~22%; the viscosity of adhesive for three corrugated board is 55~90s, the solid content is 21%~25 %. In addition, the adhesive should be adhered to the length of the adhesive (use a thumb to stick a little adhesive, and the index finger, slowly pull the two fingers to the distance between the two fingers when the adhesive breaks) is 15 ~ 20mm.
2. 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 most advantageous for the bonding and corrugating effect of the corrugated board. The difference in water content between the three base papers and the left, center and right sides of each base paper shall not exceed 3%.
(2) Raw paper production time. The production dates of the three types of base paper must be similar before they can be used on the machine.
(3) The number of times the base paper is resistant to folding. The base paper should be produced in a low-temperature and low-humidity environment. In order to prevent the quality of the carton from bursting due to the low number of folding resistance, the number of folding of the base paper must be more than 50 times.
(4) Base paper strength. The strength of the base paper is determined according to the customer's pressure resistance requirements for the corrugated box used and the production process of the carton. If the compressive strength of a box type carton reaches 1500N, through analysis and calculation, if the offset printing carton is used, the base paper should be high strength A grade, the quantitative value is 120g/m2, and the ring pressure index is greater than 7N・m/g; Or pre-printed printing carton, the base paper should be high-strength A grade, the quantitative value is 110g/m2, and the ring pressure index is more than 6N・m/g.
The choice of the strength of the base paper is complicated and must be determined after analysis, calculation and experiment according to the relevant technology. Once it is determined, the base paper must not be replaced for this type of box, and the base paper of the corresponding strength specified must be selected for production.
3. Original paper force adjustment
The original paper force should be adjusted according to the longitudinal bending of the corrugated board and the use. When the corrugated board is bent in the direction of a certain longitudinal direction of the paper, the tension of the base paper should be released. The original paper core and the outer tension control are different. The original paper force parameter must be reduced at the core to prevent the paper from breaking. If the original paper force is too large, it may cause quality problems such as broken paper, longitudinal bending of corrugated cardboard, and unsatisfactory corrugated forming effect. On the contrary, it may cause foaming and warping of corrugated cardboard.
4. Preheating wrap angle
The surface temperature of the preheating drum must reach above 100 °C, and the temperature of the hot platen must reach above 150 °C. The preheating wrap angle is proportional to the contact area of the base paper on the preheating roll and the moisture content of the base paper. During the production process, the preheating wrap angle can be increased or decreased according to the lateral bending degree of the corrugated board. For example, when the single corrugated cardboard and the three corrugated cardboard are bent in the transverse direction, which kind of base paper is bent, the preheating wrap angle of the base paper is increased, and the preheating wrap angle of the other base paper is reduced.
5. Stack paper adjustment
Although stacking paper at the bridge helps the volatilization of the corrugated board, excessive stacking of paper can cause the corrugated board to appear on the board, bend and so on. Therefore, it is necessary to reasonably control the amount of pile paper according to the effect of the board.
6. Dust removal system
When producing three-corrugated cardboard, the cleanliness of the cardboard should be ensured. The dust-removing system of the corrugated board production line should be used to remove the dust by the brush and open the suction device to reduce the printing quality caused by the paper wool in the subsequent printing process.
7. Vapor pressure and hot plate control
Ensure that the minimum vapor pressure is greater than 7kg, and the internal temperature of the hot platen reaches 150 °C before starting production. In actual production, the hot plate is reasonably adjusted according to the bending degree of the corrugated board and the speed of the vehicle. When the corrugated cardboard is bent transversely to the direction of the box, the latter set of hot pressing plates should be lifted to ensure that the internal temperature of the hot pressing plate is lowered under the premise of gelatinization. When producing corrugated cardboard with a longitudinal dimension of less than 600 mm, the machine speed should be reduced by 30% to 40%, and a set of hot-pressing plate vapor pressure devices should be closed or lifted, and the hot platen should be lifted to dissipate heat.
For pre-printed paperboard, in order to achieve quality problems at 150 °C, pre-printed paper should be made of high-temperature varnish. Once the pre-printed paper is found to have ink and varnish at this high temperature, heat should be applied. The platen temperature was lowered to 130 ° C for re-production.
8. According to the size of corrugated board
Smaller corrugated cardboard shall not be produced immediately after the production of larger corrugated cardboard. If our factory normally produces corrugated cardboard with a vertical dimension of 1020mm, if the corrugated cardboard with a small longitudinal dimension (such as less than 600mm) is replaced immediately, the internal temperature of the hot pressing plate cannot be greatly reduced due to the short time after the shutdown. Causes corrugated cardboard to undergo severe bending deformation. Therefore, the production of corrugated cardboard with a longitudinal dimension of less than 600 mm should be scheduled for the initial production of a single day.
Larger corrugated cardboard should not be produced immediately after the production of smaller corrugated cardboard. This is because the production of corrugated cardboard of smaller size is carried out at low speed and low temperature. Once the corrugated cardboard of larger size is replaced immediately, the temperature of the hot pressing plate cannot be quickly raised to the set temperature, and the gelatinization is insufficient, and the moisture is insufficient. Slow loss will make the cardboard stiffer and the corrugation is not stiff. Therefore, it must be produced after the hot platen temperature reaches the standard range.
9. Pressure regulation
The first is the pressure adjustment between the upper and lower corrugating rolls and the pressure rolls, which directly affects the corrugating effect. If the pressure is too large, there will be a phenomenon of blasting or crushing when the corrugated sheet is formed. If the pressure is uneven, the corrugated board will be unevenly thick and unevenly coated; if the pressure is too small, the corrugating effect will be deteriorated.
Followed by the adjustment of the glue gap. The gap value is inversely proportional to the pressure. The gap value is too small, that is, the pressure is too large, the stiffness of the paperboard is lowered, the height of the paper is lowered, and the compressive strength of the carton is decreased. If the pressure is too large, the pressure is too small, which affects the adhesion of the paperboard. , resulting in poor adhesion. When producing single corrugated board, the glue gap value is 3.2~3.6mm; when producing three corrugated board, the single corrugated board gluing gap value is 2.6mm, the three corrugated board gluing gap value is 2.2mm, the rubber roller and the upper pressing roller The gap value between them should be guaranteed to be 3.0 mm.
10. Speed control
The speed of the car has a great influence on the flatness of the corrugated board. Under the premise that the vapor pressure is about 7kg and the hot plate temperature is about 150°C, when the longitudinal dimension of the corrugated board is more than 600mm, the speed should be controlled to 140~160m/min; When the longitudinal dimension is less than 600 mm, the vehicle speed should be controlled to be 90-100 m/min.
11. Internal cleaning of the pressure plate
When the paper wool, paper dust or solid matter of the glue adheres to the surface of the hot plate or the surface of the adhesive tape, scratches and gullies may occur on the surface of the corrugated cardboard. At this time, it is necessary to stop the cleaning, otherwise the printing process will be followed. It is prone to quality problems that are not inked.