How to Meet Customer's Requirements for Compression Strength (4)

Safety Factor Design Method

In addition to the weight of the stacking, the impact of the carton in the circulation process is also affected by factors such as the piling time, p temperature and humidity environment, p content of the internal moisture, p vibration impact, etc. These factors can cause the carton compressive strength. It is necessary to set a safety factor to ensure that the carton, under the influence of various factors, still has enough capacity to withstand the weight of the carton stacked on it after the compressive strength is reduced.

In general, the contents can withstand a certain degree of compressive resistance, and the internal safety factor is set to about 3 to 5 when the content is a domestic product that has a short transit period. If the contents themselves emit water, or if the contents are fragile items, the stacking time is long, circulation is large, or the storage condition is poor, the safety factor is set to 5-8.

The safety factor can be calculated according to a certain method on the premise that various factors leading to the reduction of the compressive strength are determined.
1
K=-----------------------------
(1-a)(1-b)(1-c)(1-d)(1-e)...

a: Decrease rate due to changes in temperature and humidity
b: Decrease rate due to stacking time
c: Reduction rate due to stacking method
d: reduction rate caused by loading and unloading process
e: other

For example:
a: Change in temperature and humidity results in a 40% reduction in carton pressure
b: The reduction rate caused by piling time is 30%
c: The reduction rate caused by the stacking method is 20%
d: The reduction rate caused by the loading and unloading process is 10%
e: The reduction rate caused by other factors is 10%

Safety factor
1
K=---------------------------------------=3.67
(1-0.4) (1-0.3) (1-0.2) (1-0.1) (1-0.1)

Table 4 Safety Factor Design Parameters Table Temperature and Humidity Changes After Packing Temperature and Humidity Environment After packing, from the factory to the sales process, it is stored in a cool, dry and cool environment and then circulated by land. However, the temperature and humidity of the carton change greatly. After entering the container after packing, take the sea export compressive strength reduction rate 10% 30% 60%
Long stacking time after packing Stacking time Stacking time is less than 1 month Stacking time is 1 to 2 months Stacking time is more than 3 months Compressive strength reduction rate 15% 30% 40%
Stacking method after stacking Stacking method Carton stacking with corner-to-corner parallel stacking Stacking cartons can not be fully aligned at the corners of the box, but stacking and neat stacking of cartons will increase the compressive strength reduction rate 5% 20% 30%
Loading, unloading and circulation process Loading, unloading and circulation In the process of circulation, only one loading and unloading operation is performed. During loading and unloading, there are few impacts. Although loading and unloading are multiple times, the impact on the carton during loading and unloading is often unloaded from the factory to the supermarket for many times, and is often subjected to loading and unloading. Impact compressive strength reduction rate 10% 20% 50%

Other factors to consider

Other Influencing Factors Paste is added with waterproof and moisture-resistant additives (the safety factor can be subtracted from the influence of temperature and humidity on the pressure against the design). The content itself is a valuable and fragile object, and the protective requirements for the carton are very high.

Compressive strength reduction -10% 60%

For example, there is a carton. The total weight of the carton is 18 kg after loading. The maximum stacking layer of the carton is 5 layers. The carton is printed in a single color. There are two handles on both sides. The container ships are shipped to the United States and require a pit type. For BC pits, dimensions are 415 cm x 124 cm x 230 cm, please design the paper configuration.

answer:

The first step: set the safety factor because it is through the container exit, set the temperature and humidity changes led to a reduction rate of 60% carton pressure, set the reduction time caused by the stacking rate is 30%, the reduction rate caused by the stacking method is 20 %; Loading and unloading conditions are not specified, set the loading and unloading process to reduce the rate of 20%.

The safety factor 1
K=---------------------------------=5.6
(1-0.6)(1-0.3)(1-0.2)(1-0.2)

Step 2: Calculate the compressive strength according to the compression design formula P=G×(n-1) ×K
The compressive value of the carton should be P=18×(5-1)×5.6
=403kg (3955N)

The third step: According to the printing process, the compressive strength is corrected. Because the carton is printed in monochrome, and each side is used as a pull-in handle, the calculated compressive strength must be corrected in advance to compensate for the compression process. Impairment. According to the "Correction Value of Carton Compression Strength Table", the monochrome printing reduces the pressure resistance by 6%, and the handle pulls the compressive strength by 20%. The carton compressive strength should be set to:
3955×(1+26%)=4983N

Step 4: According to the formula of the compressive strength calculation, the edge pressure of the cardboard is inversely introduced. According to the size, the circumference is 1.078 m. According to the pit type, the thickness of the cardboard is 0.0065 m. The known carton pressure requirement is 3559 N.
It is then substituted into the carton pressure-reduction formula:
B=5.874×E× T×C
4983=5.874×E× 1.078×0.0065
E=10135N/m
The paperboard configuration must reach 10,135 N/m edge pressure to meet the requirements of the carton.

Step 5: Finalize a Reasonable Paper Configuration

According to the side pressure strength formula, the cardboard type, and the lateral ring pressure strength parameters of the factory base paper determine the most reasonable paper configuration, which is not listed here.