3, stacking time and stacking mode
The compressive strength of cartons decreases with the increase of stacking time. This phenomenon is called fatigue. Tests have shown that under long-term loading, as long as one month passes, the compressive strength of the carton will drop by 30%. After one year of experience, its compressive strength is only 50% of the initial value. When designing the carton material, the safety factor should be increased for cartons that have been in circulation for a long time.
The carton stacking mode also has an impact on the compressive strength of the carton. The pressure in the vertical direction of the carton is much greater than that in the transverse pit, and the carton stack should be kept pressurized in the direction of the vertical pit. From the test results, the box corners of the carton are subjected to the highest pressure, and the farther away from the box corner, the lower the bearing pressure. Therefore, when stacking cartons, the box corner should be aligned with the corners of the box (see Figure 2).
There are three common carton stacking methods: brickwork, parallelism and windmills (see Figure 3). In these three methods, the up-and-down parallel stacking is advantageous in keeping the box corners fully pressed, and thus is most reasonable. Brickwork and windmills should be avoided as much as possible.
4, carton opening method
Some cartons have vent holes, handle holes, etc. These openings also have a significant impact on the compression resistance of the carton. Tests show that the greater the opening, the greater the reduction in compressive strength; the closer the opening is to the top and bottom, the farther to the left and right the center, the lower the compressive strength; the open compressive strength is less than that of the asymmetrical opening. To be small.
In general, one handle on each side reduces the compressive strength of the carton by 20%, and a handle on each side and front side reduces the compressive strength of the carton by 30%. Some factories put a reinforced card on the opening of the inner wall of the carton box. This not only can reduce the impact of the opening on the compressive strength, but also can prevent the hand-pulled part from being damaged when it is stressed.
(to be continued)
