This standard specifies the determination of the width, roll length, warp cord, weft yarn count, density, breaking strength, breaking elongation, strength unevenness, elongation unevenness, cord diameter, initial twist and re-twist of cotton cord fabric. This standard is applicable to the test of cotton cord fabric. GB/T 2435-1994 Test method for cotton cord fabric GB/T2435-1994 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for cotton cord fabrics
Methods of testing cotton cord fabrics1 Subject content and scope of application
GB/T 2435-94
Replaces GB2435-81
This standard specifies the determination of width, roll length, warp cord, weft yarn count, density, breaking strength, breaking elongation, strength unevenness, elongation unevenness, cord diameter, initial wrapping and complex wrapping of cotton cord fabrics. This standard is applicable to the test of cotton cord fabrics. 2 Reference standards
GB2543 Test method for yarn wrapping
3 Standard atmosphere
The standard atmosphere used for the test is 20±2℃ and 65%±2% relative humidity. 4 Determination of the width, length and density of cord fabric 4.1 Determination of the width of cord fabric
4.1.1 Definition
The total width of the fabric is the distance between the two largest warp yarns of the fabric perpendicular to the length direction of the fabric. 4.1.2 Measurement principle
Measure the width at different points of the fabric with a steel ruler. 4.1.3 Measurement procedure
During the process of unwinding the cord fabric on the inspection machine, measure the width of the cord fabric with a steel ruler perpendicular to the edge of the fabric at a distance of not less than 2m from the end of the fabric, and measure evenly 5 times.
4.1.4 Measurement results
The arithmetic average of the numbers measured each time is the width of the roll of fabric, and the number is accurate to 0.1cm 4.2 Determination of the length of cord fabric
The record of the counter on the loom shall prevail, accurate to 0.25m, and rounded to an integer. 4.3 Determination of cord fabric density
4.3.1 Definition
Density refers to the number of yarns contained in a unit length of the fabric in the warp or weft direction. 4.3.2 Measurement procedure
4.3.2.1 The warp density should be determined when the cord fabric is unwound on the inspection machine. The number of warp threads in the same weft direction of 10 cm should be counted at three points, left, middle and right, not less than 2m from the end of the fabric and not less than 10cm from the edge of the fabric, with an accuracy of 0.5. 4.3.2.2 Each side of the cord fabric edge is counted as two threads. 4.3.2.3 The weft density should be measured at 5 points in the warp direction not less than 2m from the end of the fabric (the distance between each measuring point is roughly equal). The number of weft yarns within 10cm should be counted. 4.3.3 The measurement result should be expressed as the arithmetic mean of the numbers obtained in each measurement, calculated to two decimal places, and the second place should be rounded off. 5 Determination of the breaking strength, elongation and elongation of the cord 5.1 Determination of the breaking strength and elongation of the cord 5.1.1 Definition 5.1.1.1 Breaking strength The maximum tensile force measured in the test where the specimen is stretched to break, expressed in Newton (N). 5.1.1.2 Elongation at break
The increase in length of the specimen when it is stretched to break in the tensile test, expressed as a percentage of the nominal clamping length. 5.1.2 Principle of determination
The specimen is given a gradually increasing tensile force by an appropriate mechanical method to make it elongate until it breaks, and the maximum tensile force and elongation at break are indicated.
5.1.3 Conditioning of specimens
The specimens shall be conditioned under standard atmospheric conditions for 24 hours before the test. 5.1.4 Test procedure
5.1.4.1 The number of cords to be tested for each batch of cord fabrics is 100, and the two ends shall be butt-jointed to prevent the loss of the brace. 5.1.4.2 The test instrument adopts a single-pendulum strength testing machine, the distance between the upper and lower clamps is 250mm, and the lowering speed of the lower clamp is 300±5mm per minute.
5.1.4.3 Pre-tension of the cords, see Table 1. Table 1
tex×ply×ply
27×5×3
27×4×3
27×3×3
27×2×3
5.1.4.4 Breaking Strength Test Procedure
Pretension
5.1.4.4.1 The measured breaking strength of a specimen is expressed by the arithmetic mean of all test values ​​of the specimen (those that slipped or broke near the chuck during the test are excluded). The arithmetic mean is calculated to three decimal places, and the third place is rounded off. 5.1.4.4.2 Before and after the breaking strength test, weigh the specimen respectively, and obtain the average weight of the two weighings as the weight before baking.
5.1.4.4.3 When the actual moisture regain of the sample is within the range of 5% to 7%, the measured average breaking strength of the cord shall be corrected according to formula (1): 100 + 3.5 X 6.5
100 + 3.5× W
Wherein: P is the breaking strength of the cord at a moisture regain of 6.5%, N; P is the measured average breaking strength of the cord, N;
W is the actual moisture regain of the sample,%.
Calculate to two decimal places and round off the second place. 5.1.4.5 Elongation at break test procedure
5.1.4.5.1 The elongation at break test and the breaking strength test of the cord are carried out simultaneously; 12
(1)
GB/T 2435-94bzxZ.net
5.1.4.5.2 The load-elongation curve of the cord is recorded by the automatic recorder on the strength testing machine, and the measured elongation at break is obtained from the load-elongation curve.
5.1.4.5.3 The measured elongation at break of the cord is expressed as the arithmetic mean of all test values. The measured elongation at break of the cord is calculated according to formula (2):
Where: E—measured elongation at break of the cord, %; Li
-measured elongation at break of the cord, mm;
L——original length of the specimen, mm.
When the original length L of the sample is 250mm:
E= 0. 4× L
Calculate to two decimal places, and round off the second place. 5.1.4.6 The unevenness of cord strength and elongation at break shall be calculated according to formula (4): 2(X-2)n × 100
Wherein: H-
-unhooking rate,%;
X--arithmetic mean of all test values; Yuan: arithmetic mean of all test values ​​below the average; N--total number of tests;
number of test values ​​below the average.
(2))
(3)
(4)
If there are test values ​​that are equal to the average, they shall not be calculated as test values ​​below the average. The above formula shall be calculated to two decimal places, and round off the second place.
5.2 Determination of cord tension
5.2.1 Definition
a. Tensile strength
The number of yarns per unit length under a certain tension (tenors/m). b. Direction
The inclination direction of the spiral formed by the yarn winding back, represented by capital letters S and Z. The method of indicating the direction of cord tension is that the first letter represents the direction of the single yarn, the second letter represents the initial winding direction, and the third letter represents the secondary winding direction. 5.2.2 Test specimens
The number of test pieces for each batch of cord fabrics is 20.
5.2.3 Test instrument
The tension test is carried out on a Y-331 tension machine with a clamping distance of 250mm and a speed of 1500±50r/min. 5.2.4 Procedure for determination of tension direction and tension
8. Determination of the direction of the spiral: Take a sample of about 200mm in length, place it vertically, and check the inclination direction of the spiral. If it is consistent with the middle part of the letter S, it is S spiral, and if it is consistent with the middle part of the letter "Z", it is Z spiral. b. Pre-tension of spiral length: The pre-tension of the cord shall be in accordance with the provisions of the strength test. The pre-tension of the initial spiral is shown in Table 2. Table 2
tex × strand
Pre-tension
texx strand
GB/T2435-94
Continued Table 2
Pre-tension
Determination of spiral length: First measure the complex spiral length of the cord, then cut off two initial strands, measure the spiral length of the remaining initial strand, and correct it to spiral length per meter according to the actual length of the initial strand before the measurement. The initial complex spiral length of the cord is taken as an integer, calculated to one decimal place, and rounded to the integer.
6 Determination of cord diameter
6.1 Definition
The locus of the midpoints of a family of parallel chords of a quadratic curve is a straight line called "diameter". 6.2 Test specimen
The number of cords tested in each batch of cord fabric is 20. 6.3 Test instrument
Use a thickness gauge (temporarily modified with a 0~10mm first-level precision dial indicator) for measurement. The diameter of the thickness gauge clamping plate is 30mm. The E and F clamping plates should be tightly fitted, and the pressure weight of the upper clamping plate on the cord is 18.0g. 6.4 Determination procedure
a. The cord should be gently straightened, and the measurement should not be carried out at the broken seeds and cotton knots; b. Press the lever on the thickness gauge by hand and release it immediately. The buffer will slowly drop the upper clamping plate. If there is no buffer, the upper clamping plate should be slowly lowered from a height of 5mm above the sample so that the cord is not subjected to any impact; the number should be accurate to 1/100mm, and those less than 1/100mm will not be counted. c
6.5 Determination results
The cord diameter is expressed as the arithmetic mean of all the measured values ​​of a sample, calculated to three decimal places, and the third place is rounded off. 7 Determination of moisture regain of cord
7.1 Test instrument
The moisture regain is measured in an eight-basket oven, and the temperature control range in the oven is 105-100℃. The sample is dried in the oven until it has a constant weight (constant weight means that the weight change of two weighings every 10 minutes does not exceed 0.025%). 7.2 Calculation formula
Wherein: W. Actual moisture regain of cord, %;
GL= G2 × 100
Gi——weight of sample before drying, g, weighed to 0.01 g; G2---unchanged weight of sample after drying, g, weighed to 0.01 g. Calculate to three decimal places, and round off the third place. Determination of 844N elongation under constant load
Measure the elongation under constant load at a strength of 44N on the strength-elongation diagram, and the calculation method is the same as that in Article 5.1.4.5. 14
(5)
GB/T2435-—94
Appendix A
Batch regulations and sampling for physical tests
(Supplement)
A1 The physical property test of cord fabric shall be carried out in batches by the manufacturer according to the output. Each batch of cord fabric must be of the same type and the same quality specification for delivery and acceptance.
A2 Each batch of cord fabric samples must be randomly sampled on two or more looms. The sampling position is behind the loom head of the previous piece of fabric and in front of the loom head of the next piece of fabric, not less than 200mm away from the edge of the fabric, and the length of the sample is not less than 500mm. A3 When sampling, the bracket should be prevented from being lost, and the sampling shall not be selected, but the lines with serious defects shall be eliminated. Appendix B
Non-arbitration routine determination
(Supplement)
B1 Factory grading test and internal quality control test can be carried out by quickly measuring the physical properties of the cord under normal temperature and humidity conditions, and then converting the breaking strength of the corrected sample according to formula (1). B2 The sample of the rapid test should be placed in a moisture absorption cylinder containing desiccant for a certain period of time or in an electric oven at low temperature (not more than 50°C) to dehumidify, so that the moisture regain of the sample reaches 5% to 7% before testing. Additional remarks:
This standard was proposed by the Science and Technology Development Department of the Ministry of Textile Industry and is under the jurisdiction of the Shanghai Textile Standard and Metrology Research Institute. This standard was drafted by Qingdao Textile Industry Corporation. The main drafters of this standard are Ye Jiachen, Peng Jiandai and Pan Jiabiao. This standard refers to the Japanese Industrial Standard JISL3101-78 "Standard for Cotton Cord Fabric for Bicycles". Products of this standard are equivalent to the general international level.
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