Quality control of the hottest corrugated box flap

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Corrugated box flap quality control

the folding resistance of the flap is one of the important quality indicators of corrugated boxes. China's corrugated box standard gb6 polyurea technology was introduced into China 543-86 by Professor Huang Weiwei of Qingdao University of technology. It is expressly stipulated that: after the corrugated box flap is opened and closed for more than 5 times at 1800 degrees, there shall be no cracks in the surface and inner layers of category 1 and 2 boxes, and there shall be no cracks in the outer layer of Category 3 boxes, and the total length of cracks in the inner layer shall not be greater than 70mm. In addition, there are additional provisions: take any 6 boxes from the selected samples for inspection, and two of them do not meet the above requirements, Then all the cartons in this batch are unqualified. However, in actual use, some customers' requirements are much more stringent. They require that the rocker cover be folded 180 degrees outward and inward (instead of opening and closing 180 degrees). There should be no cracks in the inside and outside paper. In order to achieve this and achieve this important technical quality index, the following difficulties must be controlled:

1 Quality control of base paper

surface paper and lining paper with good texture should be selected, and the grade of paper should be above grade C. after the test, it will not crack and has good folding resistance. In addition, the core paper should also use high-strength corrugated base paper. Try to avoid using low-grade corrugated paper with rough pulp. This kind of corrugated paper may break the surface paper during shake analysis

2. Control of moisture content of base paper and paperboard

paper and paperboard are too dry, which is an important reason for the breakage of the fold line position of the shake cover. The national standard stipulates that the moisture content of corrugated base paper and carton board is about 8%-10% respectively. In actual production, of course, it should be properly controlled according to the grade of paper and equipment conditions. When the grade of paper is high, the moisture content can be lower, and when the grade is low, the moisture content can be higher. The moisture content of corrugated paperboard is set as 14% in the national standard gb6544-86, which should be the moisture content when the production of paperboard is completed. The moisture content of corrugated board is directly related to that of base paper. At the same time, it can be properly controlled by the heating amount (steam pressure) of the double-sided paper and the vehicle speed. It is better to use steam to increase the temperature during production in winter

3. The indentation control of the fold line of the shake cover

first of all, the indentation must be pressed through. The so-called pressing through is to press there is no gap. For example, the thickness of the indentation of the five-layer paperboard is generally about 2mm, not only the top of the cam, but also both sides. In this way, when the swing cover is folded outward to the bottom, a plane is formed outside the fold line, and cracks and seams will not occur. In addition, the state of the indentation depends on the state of the thread pressing wheel of the cutting machine. The technical state of the crimping wheel varies with the number of paperboard layers produced (three, five and seven layers are different). The gap between the crimping wheels (convex and concave wheels) must be consistent. Otherwise, you can't avoid adding, which can ensure that all the paperboard indentation can be just right. The fold line of the lightly pressed rocker cover may have cracks when it is folded, and the heavy one will lead to the fracture of the press line

4. Folding

shortly after the cardboard leaves the aircraft, manually folding the flap to both sides for one or two times (the solar powered aircraft has landed safely in Seville, Spain, and folded to the end) can greatly improve the folding resistance of the flap and make the carton flap crack free for a long time

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