Some standard content:
National Standard of the People's Republic of China
Method for Determination of Puncture Strength of Cardboard
GB 2679.7-—81
The puncture strength of cardboard refers to the work required to penetrate the cardboard with a certain shape of angle cone, that is, the work required to start puncturing and to tear and bend the cardboard into a hole, expressed in kg·cm (J). This method can be applied to various types of cardboard such as boxboard, corrugated boxboard, etc. 1 Sampling and processing
1.1 The samples are collected and processed in accordance with the provisions of GB450-79 "Methods for Taking Average Samples of Paper and Cardboard and Processing of Samples Before Inspection", and the test is carried out under standard temperature and humidity. 2 Instrument
2.1 The puncture strength shall be measured using a Beach puncture strength tester (as shown in the figure) that meets the following requirements. The instrument uses the pendulum cone method to produce impact.
A Cross-section of the crossbeam
1 Pointer,
2- scale plate,
3- swing arm, 4- sample fixture 1
6 Counterweight hole, 7- pierce the triangle head
5- fixing device!
The table of the instrument stand should be firmly installed on a solid foundation to avoid energy loss. The instrument should be placed in an accurate horizontal position so that it cannot vibrate during the test.
Issued by the General Administration of Standards of the People's Republic of China
Ministry of Light Industry of the People's Republic of China
Implemented on August 1, 1981
Papermaking Research Institute of the Ministry of Light Industry
GB 2679.7-81bZxz.net
2.2 The pendulum is equipped with a 90° circular arc, and the pyramid is installed on it. The pyramid should be a regular triangular pyramid with a quotient of 25 ± 0.7mm and a radius of 1.5mm for the rounded corners of the calibration edge.
One of the bottom sides of the pyramid should be parallel to the rotation axis of the pendulum, and the diagonal of the bottom should point to the rotation axis. 2.3 Clamping device, in order to fix the sample, two horizontal clamping plates are provided, the upper clamping plate is fixed, and the lower side of the upper clamping plate in contact with the sample should be in the horizontal plane passing through the pendulum axis or not higher than 7mm of this horizontal plane. The effective area of the clamping plate should not be less than 175×175mm.
There is an equilateral triangle hole in the middle of the clamping plate, with a side length of 100±2㎡m. The holes of the upper and lower clamping plates should overlap, and the radius of the circle at the angle is 3.0mm.
The minimum force applied between the clamps is 25kg [250N (Newton)], but cannot exceed 100kg (1000N (Newton). If the instrument does not have a device to measure the clamping force, then it should be used as the force used during the test to ensure that the sample does not loosen. 2.4 Reading pointer and reading disk: The test result should be expressed by the part on the reading disk where the friction load pointer points. There are many scales on the reading disk that correspond to the work range. The scales should be in kg·cm or D (joule) units. The range of the reading disk is 0~60kg·cm (0~5.89J), 0~120kg.cm (0~11.77J), 0~240kg·cm (0~23.54J), 0~480kg·cm (0~47.1J) in four gears.
The friction force of the pointer installation should be enough to enable it to move smoothly without shaking. Note: 1kg·cm=0.098 J
3 Adjustment and calibration of the puncture strength tester
3.1 For any measuring range, when the center of gravity of the pendulum is at the lowest point, the tip of the pyramid should be within the horizontal range of ±6mm passing through the pendulum's rotation axis. If it is not within the allowable range, raise or lower the balance lead for adjustment. 3.2 Adjustment of the zero point: Remove the heavy wheel and sample clamp on the pendulum, then move the pointer to the maximum value, put the pendulum in the test start position, press the release button, and the pendulum will swing. At this time, the pointer must point to the zero point, otherwise use the zero point adjustment screw on the pendulum to adjust. When replacing heavy lead of different weights, the zero point needs to be reset. Proofread. 3.3 Adjustment of pointer friction: put the pointer at zero point, lift the pendulum to the test start position, press the release button, the pendulum will swing, at this time the pointer must not exceed 3mm outside the zero point, otherwise add oil to the pointer bearing for lubrication or relax the pressure of the pointer spring to adjust it. 3.4 Calibration of pendulum shaft friction: without adding any heavy lead, release the pendulum to swing freely until it stops, the number of swings should not be less than 100 times. 3.5 Calibration of anti-friction ring resistance: after the pointer is adjusted to zero point, place an aluminum plate with an equilateral triangle hole with a side length of 81㎡m in the middle, align the hole of the plate with the hole of the specimen pressure plate, and press it on the pressure plate. The middle of the plate, then release the piercing head with the anti-friction ring fixed, observe the resistance of the anti-friction ring, which should not be greater than 0.8kg·cm (0.078J). If it does not meet the requirements, the three ball screws of the triangular piercing head can be adjusted to increase or decrease the pressure of the spring.
3.6 Calibration of the total torque of the pendulum body, add a small shaft at the rear end of the counterweight hole of the pendulum body, and install a vertical downward screw at the end of the small shaft. Put the pendulum body in the position to be released, and the lower end of the screw is against one end of the balance (or on the scale plate), release the pendulum, and add a magnetic code at the other end of the balance until the upper surface of the pendulum body is level. Until the balance reaches equilibrium, the total moment of the pendulum is calculated by the following formula: Total moment of the pendulum = Wh-Wh
Wherein: W is the weight of the magnetic code;
h is the distance from the center of the pendulum shaft to the center of gravity of the connecting screw: W\ is the weight of the connecting screw;
h' is the distance from the center of gravity of the pendulum shaft to the center of gravity of the connecting screw. 4. Test steps and result calculation
4.1 Place a sample of not less than 175×175mm between the clamps and apply a fixed force to the clamp. The sample should be clamped in the middle. If the measuring instrument is equipped with a clamping force measuring device, the force can be recorded. Adjust the pendulum and add heavy armor when necessary to select the appropriate range of work, so that the test results obtained will be kept within the range of 20-80%. Put the anti-friction ring behind the cone and turn the pointer to the highest scale value, lock the pendulum in the start test position, press the release button, the pendulum swings, and the cone completely passes through the sample. Read from the corresponding scale the total amount of work equivalent to the work used to cut through the sample and overcome the carrying effect of the measuring device, and deduct it to 1 grid. If the measuring range of the scale reading is 122.4kg·cm (12J), it should be accurate to 1kg·cm (0.1J); if the measuring range is above 122.4kg·cm (12J), it should be accurate to 2kg·cm (0.2J). If the friction effect is greater than or equal to 1%, the test result is compensated by the work loss caused by the friction of the equipment determined in advance. 4.2 In each packaging unit, 8 samples are cut from different paper samples taken out. Half of the samples are measured in the direction parallel to the swing plane of the pendulum in the longitudinal direction, and the other half of the samples are measured in the direction parallel to the swing plane of the pendulum in the transverse direction. When the longitudinal direction is parallel to the swing direction of the pendulum, the measured value is called the longitudinal puncture strength. The measurement results are expressed as the arithmetic mean of all the measured values on the front, back, longitudinal and transverse sides, and the maximum and minimum values are reported. The calculation results are accurate to 0.1 kg cm. If expressed in J, the value is less than 12 J, and is accurate to 0.1 J, and the value is greater than 12 J, and is accurate to 0.2 J. Note: From the date of implementation of this standard, the original standard QB495--64 is invalid.
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