Corrugated box material testing items and testing methods II

5 piercing strength

The work done by corrugated paperboard with a certain shape of a pyramid is called the puncture strength of corrugated paperboard. Its unit is: J. The puncture strength index is measured by a puncture strength tester. During the test, 3 good-looking sample boxes are selected. Each of the sample boxes has 4 blocks of no damage, no watermark, no crease and no Other defects in the appearance of cardboard, specifications for the 175mm x 175mm test sample 12 pieces. When cutting the specimens, it should be noted that the starting line is parallel to the corrugation. The zero calibration of the instrument should be performed prior to each test. The method is:

1 After removing the weight and the specimen splint, place the pointer at the maximum position and place it at the position where the test was started. After pressing the release device of the pendulum, swing the pendulum so that the pointer points to the "0" position; otherwise, tighten it. Adjust the screw to adjust;

2 According to the general strength of the sample, select the appropriate weight, so that the measured value in the measurement range of 20% to 80%;

3 firmly clamp the sample in the middle of the test board, the pointer dial to the highest scale value, the friction ring sleeve behind the pyramid, the lock to the starting position of the test,

4 Press the release device so that the swing arm pushes the pyramid through the sample and then reads the test value;

5 Determine the arithmetic mean of the values ​​of the front, back, portrait, and landscape, and retain 3 significant digits.

When testing, it should be noted that: the sample needs to be clamped. If slip occurs, the test value should be considered invalid. The puncture strength of corrugated cardboard is closely related to the fiber's toughness, hardness, tightness, moisture content, the adhesive strength of cardboard and the thickness of cardboard.

6 burst strength

Corrugated board under a certain detection conditions, the unit area can withstand the maximum vertical pressure, the corrugated board burst strength, its unit is expressed in kPa (Kpa). Sampling should pay attention to: to cut without watermarks, folds, wrinkles, damage, specifications 140mmx140mm 12 samples, that is, from the 3 sample boxes, each take four, one side of the sample should be made of corrugated Parallel. In the burst strength test, the specimens were divided into two groups. One group was applied to the rubber film on the front side, and the other group was attached to the rubber film on the reverse side. When the specimen was crushed, the test value was read. The sum of the test values ​​of each sample is divided by the number of samples as the test result. Bursting strength has a certain relationship with the fiber's toughness, hardness, paper thickness, tightness, moisture content, and the adhesive strength of paperboard.

7 folding degree

As a kind of packaging container, the carton needs to be frequently opened for the swing cover. This requires that the paper should have a certain folding-resistant ability. The paper's transverse folding resistance measures the paper's 135° angle reciprocating folding test on a 150mm x 15mm gauge sample under a certain tension, speed, and angle. When the paper is broken, it is the proof-folding test. frequency. The characteristics of the pulp, the moisture content, the tightness, the fiber length and the binding fastness of the baseboard paper, and the influence of factors such as the storage time and temperature of the base paper, largely determine the folding resistance of the base paper. Therefore, to improve the folding resistance of the carton, the quality of the good base paper is important.

8 ring pressure strength

A certain size of sample is inserted into the circular tray to form a circular ring on the side of the sample, and then the compression of the compressor is performed on the pressure plate for uniform compression. When the sample is crushed, the displayed value is the ring pressure. strength. The specifications of the standard sample shall be: length (longitudinal) 152.0mmi 0.2mm, width 12.7inm ± 0.1mm, take 10 8 for testing, 5 of which are tested outwards, and the other 5 are loaded outwards The circular trays were tested separately. After that, the average of the ten test results was used as a conversion. In order to improve the accuracy of detection, attention should be paid to careful detection of good quantitative indicators, and reading them as quantitative detection values ​​has a direct impact on the results after conversion from the ring pressure index. Therefore, the quantitative test sample should have a certain representative, it is best to take 10 samples from different parts of the paper tube for testing, find the average value, so that the test is relatively accurate. If 10 samples are taken from a longitudinal part of the paper cylinder, the detection value is often not representative, because the lateral thickness error of the paper tube is relatively larger than the longitudinal error. In addition, the accuracy of the test sample thickness is also related to the test results of the crush strength. Because of the different thicknesses of the specimens, the diameter of the core used for detecting the ring pressure is also different. Therefore, the thickness test should also be used to test children's points in different parts and find the average value as the final test result. The thickness index is accurately detected, and the gap between the sample placed in the tray is appropriate, which can ensure the accuracy of the ring pressure strength detection. This requires that the appropriate tray size (diameter) must be selected in strict accordance with the thickness of the sample. The tightness and quantification of the base paper greatly affect its crush strength. For a paper with good crush pressure, the ring pressure index is also correspondingly high; only by first measuring the ring crush strength value, can we obtain the cir- culation index value. The following is the formula for the conversion of the cir- culum pressure and the ring crush index:

1 Ring crush strength: R=F/152. Where R denotes the ring pressure strength in kN/m; F denotes the force reading when the sample is crushed, unit N; 152 denotes the length of the sample in mm.

2 Central pressure index: Rd=1000R/W. In the formula: Rd represents the ring pressure index, the unit N · m/g; R represents the ring pressure strength, the unit KN/m: W is the sample quantification, the unit g/m2.

(to be continued)