**Rapid Design of Compressive Strength of Corrugated Box 0201**

China's corrugated carton packaging industry has made great progress in more than 20 years. The changes in recent years are even more rapid. Some sophisticated science and technology have been applied to the industry, but due to the late start, we used corrugated paper. Some of the box design processes are still used abroad, especially the calculation method of the compressive strength of the corrugated box empty box. The foreign formulas are too cumbersome and difficult to understand. It is difficult to combine the price design of domestic cartons with the design of the compressive strength of empty containers. This can easily lead to the waste of raw materials or the quality problems in the compression resistance of cartons.

To compensate for these deficiencies and enhance the predictability of compressive strength before carton production, after a long period of measurement and verification, I have found a simple and effective method for calculating the compressive strength of empty carton boxes using the physical properties of the base paper. The formula for calculating the compressive strength of the box is written and discussed with everyone. This article only discusses the design of the 0201 type three-layer corrugated cardboard box compressive strength in this method.

The corrugated carton consists of various layers of corrugated paper. The formula for calculating the compressive strength of corrugated cartons is based on the physical properties of the original paper to calculate the compressive strength of the carton to see if it meets the requirements. It may also be based on the compressive strength requirements of the corrugated box. Select the appropriate corrugated paper.

P=Px. K

P - the empty box compressive strength of corrugated boxes (units N)

Px - the transverse integrated crush strength of base paper (units N/cm)

Three-layer corrugated board raw paper composite ring crush strength = (paper ring pressure value R1 + paper ring pressure R2 + paper ring pressure R3 x corrugation shrink rate C) / 15.2

The ring pressure value in this paper refers to the horizontal ring pressure value (unit: N/0.152m), which can be obtained through testing, or can be calculated according to the level of the base paper and the ring pressure index.

Ring pressure value R = quantitative W (units g/m2) Ã— ring pressure index r (units N.m/g) Ã— 0.152 (units m). There are some differences between the test value and the calculated value of the same kind of paper ring pressure value, and the general test value is larger than the calculated value. This is because the internal control standards of each paper mill are higher than the national standard, and both data can be used for compressive strength. The calculation.

K - The effective value of the integrated ring pressure in the compressive strength of the empty carton. The formula is:

Three layers Aæ¥žK=30.3+0.275Z-0.0005Z2

Three layers Cæ¥žK=27.9+0.265Z-0.0005Z2

Three layers Bæ¥žK=24.6+0.235Z-0.0005Z2

The product of the combined ring crush strength and its effective value in the carton is the compressive strength of the carton. C represents the shrinkage rate, the shrinkage ratio of Aæ¥žC=1.532, the shrinkage ratio of Bæ¥žC=1.361, and the shrinkage ratio of Cæ¥ž=1.477. Z represents the perimeter of the carton (ranging from 70 cm to 200 cm).

Example 1 A three-layer C-paper box with a circumference of 125cm, A-level 250g/m2 board paper for face paper and back paper, and A-grade 170g/m2 high-strength corrugated paper for pick-up paper were used to calculate the compressive strength of the carton. .

Solution: The shrinkage of Cæ¥ž is C=1.477; the national index, the ring pressure index of surface paper and liner paper is 10.6, and the ring pressure index of æ¥ž paper is 9.2; Z=125.

R1=R2=250Ã—10.6Ã—0.152=403

R3=170Ã—9.2Ã—0.152=238N

Substitute into the formula

(R1+R2+R3Ã—C)/15.2Ã—(27.9+0.265Z-0.0005Z2)=(403+403+238Ã—1.477)/15.2Ã—(27.9+0.265Ã—125-0.0005Ã—1252)= 76Ã—53.2=4043N

This corrugated box can achieve a compressive strength of 4043N.

Example 2 The length of a three-layer A cardboard box is 148cm, the compressive strength is 4500N, the surface paper and the inner paper use the B-level 250g/m2 boxboard paper, and the paperboard uses the A-grade high-strength corrugated paper. The calculated paperboard should be selected. Quantitative.

Solution: The ring pressure index of paper and paper is 9.2

Let the quantitative W of the crepe paper be unknown, A-collapse rate C=1.532, Z=148, P=4500

R1=R2=250Ã—9.2Ã—0.152=350

(R1+R2+R3Ã—C)/15.2Ã—(30.3+0.275Z-0.0005Z2)=

P(350+350+R3*1.532)/15.2*(30.3+0.275*148-0.0005*1482)=4500

R3=287

R3=WÃ—9.2Ã—0.152=287

W=205g/m2

The corrugated carton should use 205g/m2 A-grade high-strength corrugated paper.

I worked on the long-term verification of the Kelly Carter formula, and through testing in other companies' production processes, I found that there is a certain relationship between the calculated value of compressive strength and the measured compressive value after carton forming. The set of compressive formulas I calculated was compared with the Kelly Carter formula. The calculated values â€‹â€‹of the two formulas are very consistent.

It is worth noting that even with the use of similar papers, the compressive strengths that can be achieved after molding the carton with the same specifications are different due to the differences in the production processes of the companies. Some of them are close to or lower than the calculated value of the ring pressure. Some of the compressive strengths are close to or even higher than the compressive strengths calculated using the ring pressure test values. The theoretical calculation can guide the work of controlling the compressive strength of the carton in each process of the production process, eliminate various factors that affect the compressive strength, improve the product quality, and reduce the production cost.

(to be continued)

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