Analysis of the end-press strength of color box in vertical and horizontal corrugated mixed state

Model GT100 rear seated color box, external size is 415*65*, because the color box width outside the size is smaller, according to the enterprise standard Q/GTS C0002-2001B requirements, the box is not the top pressure project inspection, but the end pressure project test. Breakage standard requirements ≥ 1.0Mpa, end pressure strength ≥ 200kgf.

In the end pressure test, the front and back flaps of the box are in the form of vertical tiles, and the side and side flaps are horizontal and vertical. This makes it difficult to calculate the theoretical compressive strength of the Maji formula. If it is not possible to correctly predict the integrated end-pressure strength of the horizontal and vertical corrugations presented in the state of the carton lying in the terminal pressure test, it is impossible to correctly predict the material configuration of the color box corrugated base paper, and the price of the box cannot be correctly predicted, and the color box is also produced in batches. And quality assurance is confusing.

This article will calculate the compressive strength of the four side flaps and the side panels of the color box with the vertical back flap during the end pressure test, the lateral flap with the lateral pressure test, and can effectively predict the comprehensive status of the horizontal and vertical corrugations. The end of the carton pressure, the calculation method is not mature enough, is a new attempt to use the Machi formula, but also need to gradually improve in practice.

First, GT100 rear seat color box material, outside size, cover structure

Packaging company printed GT100 (rear) color box material for the face paper: Tianteng / m2 gray-white board, corrugated: T2 / m2 Hailong brand recycled cattle card, the paper: Hailong 140 / m2 Hailong card Niu card. Covered with BOPP matte film: Part No. PP-18, Starlight does not provide data such as thickness and burst resistance. After testing, its burst strength is 145Kpa.

Listen Gray Board: Lateral stiffness ≥4.75 mN.m (Note: There is no data of lateral pressure, and the lateral pressure is 6.0 Nm/g temporarily), the front of the burst resistance index is ≥2.41 Kpa.m2/g, and the reverse is ≥1.83 Kpa. .m2/g, average burst index ≥ 2.12 Kpa.m2/g

T2: /m2 Hailong Second Class Renewed Niuti Card: Central Pressure Index ≥6.0 Nm/g, Burst Resistance Index≥2.2 Kpa.m2/g

Hailong 140: /m2 Hailong Second Class Cattle Card: Central Pressure Index ≥ 7.4 Nm/g, Burst Resistance Index ≥ 2.4 Kpa.m2/g

GT100 rear seat color box size:415*65*

Shake cover: 0203 Folding cover On the basis of the box type, there is a long tongue on the front and back flaps, and a lock tongue hole structure on the front.

Second, calculate the theoretical value of burst strength

A. Calculation of Theoretical Value of Breaking Strength in Uncoated State

BST=(300*2.12+140*2.4)*0.95=(636+336)*0.95= 972*0.95= 923.4 Kpa

B. Breaking strength theoretical value of film

After testing, PP-18 material number BOPP matt film burst strength = 145 Kpa

GT100 rear compartment color box BST = theoretical value of non-laminated burst strength + matt film burst strength 145 Kpa= 923.4+145= 1068.4 Kpa≈1.07 Mpa

Third, ECT side pressure strength theoretical value calculation

E corrugation rate according to 1.2

LBF/IN = KN/M*5.588

In the end-pressure test, the cardboard box was placed in a vertical corrugated state at the flap cover of the color box, and the side of the color box was horizontally corrugated. The vertical and horizontal corrugation states are calculated separately.

Vertical roof tile ECT vertical tile=300*6.0+110*6.0*1.2+140*7.4=1800+792+1036=3628 N/M=3.628*5.588 lbf/in =20.27 lbf/in

Calculation of the lateral compressive strength of horizontal corrugated cardboard: The strength of the corrugated paper in the state of horizontal corrugated cardboard is neglected. The lateral compressive strength of horizontal corrugated cardboard is equal to the surface pressure of the paperboard + the pressure in the paper.

Horizontal wattage ECT tile = 300*6.0+140*7.4=1800+1036=2836 N/M=2.836*5.588 lbf/in =15.85 lbf/in

Fourth, the use of Machi formula to calculate the theoretical value of terminal pressure strength

Color box end pressure strength calculation instructions: the overlapped inner and back side flaps, 4 side flaps compressive strength alone calculation, horizontal tile, vertical tile strength calculation separately; flap cover with open hole bolt structure, according to conventional and The box keyhole structure of the actual situation, compressive strength loss rate to take 5% (loss rate a = 5%).

P=5.874*ECT*(tZ)0.5*(1-a)

ECT---Corrugated board side pressure strength (lbf/in)

Z ---- Corrugated bottom perimeter (in)

t----Board thickness (in)

a----Cardboard die cut hole compressive strength loss rate

A known:

ECT shingles=20.27 lbf/in

ECT Tile = 15.85 lbf/in

The length of the bottom of the carton

The width of the bottom of the carton

Perimeter Z=length*2+width*2= (0.68+0.415)*2

Thickness t

When the end-compression strength test is performed, the face of the 680* corrugation is parallel to the ground.

Tiles long Z vertical tiles = positive swing length * 4

Width of the cardboard tile Z = 2 lateral +4 side flap =*2+*4=1360

P = (compressive strength of the transverse strake + compressive strength of the vertical shim) * (1 - loss of compressive strength of the shroud opening a) = { 5.874 * ECT shingle * (tZ shingle) 0.5 + 5.874 * ECT shingle *(tZ tiles) 0.5}*(1-5%)={5.874*20.27*√[0.07874*65.35)]+ 5.874*15.85*√[0.07874*55.04] }*95%={119.07 * √5.15 + 93.1*√4.33 }*95%={119.07*2.27 + 93.1*2.08}*95%={270.29 + 193.65}*95%=63.94 LBF*95%=463.94 *5.588 N*95%=2592.5 N*95% =2592.5 /9.8 kgf *95%=264.5 kgf*95%=251.3 kgf

V. Conclusion

1. The theoretical rupture strength of the GT100 rear seat color case is 1.07 Mpa.

2. Calculated using the Machi formula, the theoretical value of the end-pressure strength of the vertical and horizontal corrugated box in the GT100 rear seat is 251.3 kgf.

The box material configuration, its burst strength, end-compression strength theoretical value can meet the standard requirements.

Remark: The material of the BOPP matte film on the surface of the GT100 rear seat color box is not included in the compressive strength calculation due to the absence of the ring pressure and bursting resistance specifications.