Corrugated box flap cover quality control

Rolling cover folding resistance is one of the important quality indicators of corrugated boxes. China's corrugated cardboard box standard GB6543-86 expressly states that: Corrugated box flaps can be reciprocated more than 5 times by opening and closing 1800 degrees. There should be no cracks in the surface layer and the inner layer of category 1 and 2, and there should be no cracks in the outer layer of category 3 boxboards. The total length of cracks in the layer shall not exceed 70mm, and additional provisions shall be made: from the selection of samples to take 6 cartons for inspection, if two of them do not meet the above requirements, the batch of cartons shall all fail. However, in actual use, some customers' requirements are even more stringent. They require that the flaps should be folded 180 degrees outwards (rather than 180 degrees). While doing the box process can achieve this, to achieve this important technical quality indicators, we must control the following difficulties:

1. The quality control of the base paper should use a good texture paper and paper. The grade of the paper should be above grade C. After the test, no cracking, good folding resistance. In addition, high strength corrugated base paper should also be used for core paper. Try to avoid the use of rough, low-grade pulp to make corrugated paper. This type of corrugated paper may cause the topsheet to burst during the shake analysis.

2. Control of moisture content of base paper and paperboard Paper and paperboard are too dry is an important reason for the broken position of the fold line of the flap. The national standard stipulates that the moisture content of the corrugated paper and cardboard is 8%-10%, respectively, in actual production. Of course, it should be properly controlled according to the grade of the paper and the condition of the equipment. When the grade of the paper is high, the moisture content can be lower, and when the grade is low, the moisture can be higher. The moisture content of corrugated board, the national standard GB6544-86 specifies 14%, this should be the production of cardboard to complete the water content when leaving the machine. The moisture content of corrugated board has a direct relationship with the moisture content of the base paper. At the same time, it can be properly controlled by the heating amount (steam pressure) and the vehicle speed of the double-sided paper. It is best to use steam to increase the temperature during winter production.

3.Indentation line control of the fold line first indentation must be pressed through, the so-called pressure through, is to press without gaps, such as the thickness of the five-layer cardboard indentation is generally about 2mm, not only the top of the cam to be pressed through, Both sides must be crushed. In this way, when the flap is folded outwards to the bottom, a flat surface is formed outside the fold line so that cracks do not occur. In addition, the condition of the indentation depends on the condition of the cutter presser. The technical state of the pinch roller is different from that of the production of different layers of cardboard (three, five and seven layers are different). The gap 1 (convex and concave wheel) of the pinch roller must be consistent. Otherwise, it is not guaranteed that all paperboard indentations will be just right. When the flap is lightly folded, the fold line may have cracks, and the heavy pressure may cause the pressure wire to break.

4. Folding Soon after the cardboard is removed from the machine, manually folding the flaps on both sides of the flap once or twice (folding in the end) can greatly increase the folding endurance of the flaps, enabling the flaps of the cartons to last longer without cracking.