QB/T 1809-1993 Leather stretch setting test method

This standard specifies the test principle, test instrument, sample preparation, test steps and calculation, and test report for the stretching and shaping of leather under specified conditions. This standard is applicable to all upper leathers. QB/T 1809-1993 Leather stretching and shaping test method QB/T1809-1993 Standard download decompression password: www.bzxz.net

Light Industry Standard of the People's Republic of China
Test Method for Leather Stretch Setting
Subject Content and Scope of Application
QB/T1809--1993
This standard specifies the test principle, test instrument, sample preparation, test steps and calculation, and test report for leather stretch setting under specified conditions.
This standard applies to all upper leathers.
2 Reference Standards
GB/T4689.2 Leather
3 Test Principle
Air Conditioning of Test Pieces for Physical Properties Test Under specified temperature and humidity conditions, the round leather test piece is pushed into a round cap shape. Due to the elastic effect, the round cap gradually returns to its original shape after the top force is eliminated. The percentage of the area after a certain period of recovery to the maximum stretch area is called the leather stretch recovery setting percentage. This is used to indicate the stretch setting performance of leather.
4 Instruments and Materials
4. 1 Stretch Setting Tester See the figure below.
E fixed ring, F—test piece; G—piston; H—push rod; —cylinder; K—lower clamp ring; L—upper clamp ring; M-screw; N—pullback rod; P micrometer; Q—steel bridge body; R—air guide hole S—air guide hole extension and shaping measuring instrument
Approved by the Ministry of Light Industry of the People's Republic of China on July 29, 1993
Implementation on March 1, 1994
Each part shall meet the following requirements:
QB/T 1809--1993
a. Fixed ring (E): copper ring, 2.54mm thick, 95.25mm outer diameter, 69.85mm inner diameter. b. Piston (G): The upper end of the piston is round cap-shaped, with a bottom diameter of (69.85±0.13)mm and an arc radius of (51.56±0.25)mm. The piston shall be made of heat-resistant and heat-conductive rigid materials above 100°C. The piston is pushed by the push rod (H). c. Metal cylinder (J): The piston (G) and the push rod (H) can move freely up and down in the cylinder, and an air guide hole (R) is opened at the lower end of the cylinder. d. Clamping ring (K) and (L): The lower clamping ring (K) is connected to the cylinder (J) as a whole. There is an upper convexity on the inner side of (K), and its height and width are both 1.59mm. There is an air guide hole (S) outside the convexity. There is a groove on the inner side of the upper clamping ring (L), which is just enough to place the fixing ring (E). The centers of the fixing ring (E), the cylinder (J), the clamping ring (K) and (L) should be on the same straight line. e. Pressure screw (M): At the lower part of the push rod (H), it can be turned and pressed to push the push rod H and the piston (G) upward. f. Pull-back rod (N): After loosening the pressure screw (M), pull the push rod (H) and the piston (G) back to their original positions. g. Micrometer (P): Installed in the middle of the steel bridge (Q), can be moved up and down, and can directly read 0.025mm. h. Calibration sheet: round steel sheet, 2.54mm thick, 95.52mm in diameter, used to calibrate the zero point of the micrometer. 4.2 Oven: can maintain (80±2)℃.
4.3 Adhesive: chloroprene rubber.
4.4 Saturated sodium chloride solution.
5 Sample preparation and micrometer zero point adjustment
5.1 The sample is taken from the finished upper leather and is at least 10cm away from the edge and the back line. 5.2 The test piece is round, with a diameter of 88.90mm, and there are four in total, numbered A, B, C, and D. 5.3 The test piece should be air-conditioned according to GB/T4689.2 before testing. 5.4 After weighing the air-conditioned B and D test pieces, hang them in a sealed container containing a saturated sodium chloride solution at a temperature of (20 ± 2) °C for 48 hours, weigh them again, and calculate the weight gain percentage. 5.5 Adjustment of the micrometer zero point: Place the calibration piece on the lower clamp ring (K), put on the upper clamp ring (L) and the steel bridge body (Q), and tighten them. Adjust the micrometer until the micrometer just touches the calibration piece, and lock the micrometer. 6 Test steps
6.1 Cold expansion method: Test test pieces A and B.
6.1.1 Place the test piece on a flat surface with the grain side facing up. 6.1.2 Apply a thin layer of chloroprene glue evenly on the surface of the fixing ring (E), gently place it on the test piece, make the centers of the two overlap, and apply pressure to make the fixing ring (E) and the test piece firmly bonded. Note that there should be no sliding between the two to avoid contaminating the movable part of the test piece with the adhesive. 6.1.3 After the adhesive is fixed, place the fixing ring (E) with the test piece stuck on it into the lower clamp ring (K) of the extension tester, press down the upper clamp ring (1.), and lock it. wwW.bzxz.Net
6.1.4 Place the steel bridge body (Q) with the dial gauge adjusted on the extension tester, and dial up the dial gauge to (13.59±0.03) mm. 6.1.5 Rotate the pressure screw (M) to raise the piston as quickly as possible until the test piece just touches the dial gauge. At this time, the test piece has risen to 13.59 mm and formed a round cap shape. Immediately record the time and place it in air with a temperature of (20±2)°C and a relative humidity of (65±2)% for 24 hours, then loosen the pressure screw and lower the piston.
6.1.6 After placing in air at a temperature of (20 ± 2) °C and a relative humidity of (65 ± 2)% for 24 h and 168 h, measure the dome height h of the test piece and calculate the stretch recovery percentage. 6.2 Thermal expansion method: Test test pieces C and D.
6.2.1 According to the provisions of 6.1.1 to 6.1.5, stretch test pieces C and D to a dome height of (13.59 ± 0.03) mm. Immediately place the sample together with the stretch measuring instrument in an oven that can maintain (80 ± 2) °C and bake for 60 min. 6.2.2 Take out the measuring instrument and place it in air at a temperature of (20 ± 2) °C and a relative humidity of (65 ± 2)% for 120 min. Loosen the pressure screw and lower the piston.
QB/T1809-1993
6.2.3 According to the provisions of 6.1.6, measure the round neck height h of test pieces C and D, and calculate the stretch recovery setting percentage. 7 Calculation
13.59×100
Where: S——stretch recovery setting percentage, %; h. Test piece recovery setting height, mm.
8 Test report
The test report should include the following:
The weight added by test pieces B and D after adjustment with saturated sodium chloride solution; List the stretch time, stretch recovery time and corresponding stretch recovery setting percentage of the four test pieces; Storage of samples and test conditions;
Temporary factors that may affect the test results. Additional remarks:
This standard is proposed by the Quality Standards Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Fur Leather Standardization Center. This standard was drafted by the Fur and Leather Industry Scientific Research Institute of the Ministry of Light Industry. The main drafters of this standard are Chen Yingyuan and Liu Haiyan.
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