Corrugated cardboard box anti-pressure analysis of factors (1)

Corrugated cartons are sometimes confused by the return of the carton due to insufficient pressure resistance. So, what is the reason why the pressure is not enough? What are the factors that affect the resistance of corrugated boxes? Can the corrugated paperboard pressure resistance be predicted based on the used paper? Corrugated cardboard boxes in the circulation process need to have much pressure? If you already know the required pressure resistance of corrugated boxes in the process of circulation, how should you choose the base paper composition of corrugated cardboard? These problems are the problems that this article wants to solve. They are also the concerns of corrugated cartons.

In Appendix C of GB/T 6543-1986 “Corrugated Paper Boxes”, the following provisions have been made for the resistance of corrugated boxes:

C.1 Corrugated box compressive strength value P (kgf/cm2) should not be less than the calculated value of the following formula:
(kgf/cm2)

Where: K-intensity factor;
G—mass of cargo loaded in corrugated boxes, kg;
H-stack height, cm;
H—box height, cm;
S - bottom area, cm2.
C.2 The strength factor K is determined based on the shelf life and storage conditions of the cargo loaded in the carton:
Storage period is less than 30 days K = 1.6
Storage period 30 days to 100 days K=1.65
Storage period more than 100 days K=2

There are three problems with this provision:

1 The P in the formula is called the compressive strength of the corrugated box, and its unit kgf/cm2 is also the unit of the strength. Of course, the magnitude of the compressive strength is related to the area S of the carton bottom. However, in fact, what we usually use is the pressure resistance of a corrugated box, and its unit N or kgf is a unit of force. The magnitude of the resistance pressure is not related to the area S of the carton bottom.

SN/T 0262-1993 "Procedures for Inspection of Corrugated Paper Containers for Export Packaging of Goods" noted this issue and corrected it.

2 The G in the formula is the quality of the cargo loaded in the corrugated box. Strictly speaking, it should be the total mass of the corrugated box and the corrugated boxes and all the packing materials in the box, but this may be for the convenience of the corrugated box design. The simplification.

3 The intensity coefficient K is specified to be low. As to how much this strength factor K should be equal, this is the issue to be discussed below. To solve this problem, we must first understand the corrugated box pressure resistance and what factors.

Factors affecting the resistance of corrugated boxes are divided into basic factors and changing factors. The so-called basic factors that corrugated board itself has on the pressure resistance of corrugated boxes include: the ring-press strength of the base paper, 楞 type (A, B, C type, etc.), the type of corrugated board (single corrugated, double corrugated, three Corrugated, etc.), Water content of corrugated board

In the design, manufacture, and circulation of corrugated boxes, there are a number of changing factors that can have a significant impact on the resistance of corrugated boxes:

The influence of basic factors on the pressure resistance of corrugated boxes is obvious and must be considered when designing corrugated boxes. Among these changing factors, the box type, size and balance, printing design and printing area of ​​the carton are issues that the user has to study; carton production technology, box making machinery and quality management during production are the manufacturers of corrugated boxes. The problems that must be solved; and these changes in circulation are the issues that the departments involved in circulation should pay attention to, and they must also be considered when designing.

one. Basic factors affecting the resistance of corrugated boxes

â–²1. The effect of the raw paper ring pressure strength

The corrugated paperboard's resistance to pressure is closely related to the linerboard, corrugated paper, and their combined structure used in corrugated paperboard. The relationship can be from ring pressure strength (base paper), side pressure strength (cardboard), pressure resistance (carton) and even The stacking code strength (palletized) constitutes a continuous characteristic, as shown in Figure 1.

As for the quantification of the effect of the base paper crushing strength on the pressure resistance of the corrugated box, please refer to the Kailikart formula introduced later.

â–²2. Effect of corrugated cardboard type

The corrugated type of corrugated cardboard has an effect on the pressure resistance of a corrugated box, mainly because different cardboard types have different thicknesses. Not only is the smaller the thickness of the corrugated board, the less material the board can bear, and that from a structural mechanics point of view, the compressive load that the board can withstand perpendicular to its thickness is inherently greater than the thickness of the board. Relationship. Therefore, the thinner the cardboard, the lower the pressure resistance of the cardboard box, ie, after being subjected to pressure, it is easier to bend, deform and press. It is for these reasons that the order of the pressure resistance of different carton boxes is the following: A楞>C楞>B楞>E楞.

However, the “maximum strength” of corrugated cardboard is sometimes not the most important factor in carton packaging. The most important thing is to consider the deformation of the cardboard after it is loaded. Figure 2 shows the deformation of various corrugations under load. It can be seen from the figure that under the same load size, the largest deformation is A楞, followed by C楞, followed by B楞. After wrapping a product in a corrugated box, it is not always desirable to deform the corrugated box and affect the product in the box. Therefore, if the pressure resistance of the B-carton is sufficient, it is not always necessary to use A to fight for maximum pressure resistance. Instead, the B-case should be used because its deformation is much smaller than that of A.

Therefore, when considering the pressure resistance of a corrugated box, the maximum load should be large, the individual differences of the carton should be small, and the deformation of the carton after compression should be small.
(to be continued)