This standard specifies the test equipment, sample specifications and shapes, test procedures and calculation methods for the test results of stress relaxation of flexible graphite sheets. This standard is applicable to stress relaxation tests of flexible graphite sheets with a thickness of not less than 0.3 mm and a density of not less than 0.90 g/cm3. JB/T 6625-1993 Test method for stress relaxation of flexible graphite sheets JB/T6625-1993 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T 6625-1993
Flexible Graphite Plate Stress Relaxation Test Method
Published on May 7, 1993
Ministry of Machinery Industry of the People's Republic of China
Implementation on January 1, 1994
Mechanical Industry Standard of the People's Republic of China
Flexible Graphite Plate Stress Relaxation Test Method
1 Subject Content and Scope of Application
JB/T 6625-1993
This standard specifies the test equipment, sample specifications and shapes, test steps and calculation methods for test results for testing stress relaxation of flexible graphite plates.
This standard is applicable to stress relaxation tests of flexible graphite plates with a thickness of not less than 0.3mm and a density of not less than 0.90g/cm. Test equipment
Stress relaxation tester (as shown in Figure 1):
Constant temperature drying oven.
Bisection table
Deputy measuring awning
Pingxi board
Specimen assembly
Micrometer short assembly
Clamping screw
Measuring seat
Figure 1 Stress relaxation tester
Note: The loading bolt in the tester must be calibrated, that is, when it is loaded with 26.7kN, its elongation is 0.122~0.127mm. 3 Specimens
The size of the specimen is 32mmx10mm.
3.2 Each test requires 3 groups of specimens, 4 in each group. The thickness difference of the specimens should not be greater than 0.05mm. 3.3 The surface of the specimen should be flat, the edges should be neat, and there should be no defects such as bubbles, cracks, wrinkles, delamination, scratches and obvious impurities. 4 Test steps
4.1 Clean the surface of the flat circular plate and apply low-viscosity oil to the threads of the washers and bolts. 4.2 Clamp the prepared four specimens between the two flat circular plates as shown in Figure 2. Install the bolts, put on the washers, and tighten the nuts by hand. Approved by the Ministry of Machinery Industry on May 7, 1993
Implemented on January 1, 1994
JB/T 6625-1993
3 Install the dial gauge assembly on the bolt and tighten it by hand, then adjust the dial gauge pointer to zero4.3
Flat drawing board
2 Arrangement of specimens
4.4 Continuously tighten the nut with a wrench, and make the dial gauge reading reach the bolt's calibrated elongation (D,) within 3s and keep it for 3S4.5 Remove the dial gauge assembly, put the specimen assembly into a constant temperature drying oven at 100+2℃, keep it for 22h, then take it out and cool it to room temperature in the air.
4.6 Repeat Section 4.3.
4.7 Loosen the nut (without affecting the dial gauge assembly), and read the dial gauge reading (D,).
5 Test results and calculations
The stress relaxation rate is calculated according to formula (1):
Stress relaxation rate = Do = D1×100%
Elongation of the bolt before heat treatment, mm:
Where: D.
D, elongation of the bolt after heat treatment and cooling, mm. The test results are expressed as the arithmetic mean of the three groups of specimens, with two significant figures. 5.2
Test report
The test report should include the following contents:
Indicate the number of this standard:
b. Product specifications, brand, manufacturer;
Sample thickness, density:
Test results;
Test date, personnel.
A1 Equipment and conditions
Tensile testing machine: precision level 0.5,
b. Fixture;
Temperature: room temperature.
Operation steps
Process).
JB/T6625-1993
Appendix A
Loading bolt calibration method
(reference)
The measuring range is not more than 50kN;
Install the loading bolt on the fixture according to Figure A1 and tighten the nut by hand. Adjust the dial gauge reading to zero (a margin greater than 0.15 mm should be left). A2.2 Use a tensile testing machine to uniformly apply loads of 0, 4.45, 8.90, 13.35, 17.80, 22.25, and 26.70 kN to the bolts, and record the elongation of the bolt under each load (accurate to 0.001 mm). Remove the load on the bolt. If the dial gauge reading cannot be restored to within ±0.0025 mm, the data is invalid and should be tested according to A2.1~A2.2A2.3. t||Redo the item.
A2.4 Carry out the steps of A2.1 to A2.3 for 3 times. Data collation
Draw the relationship curve between each load and the bolt elongation under each load (average of 3 times) on the coordinate paper. The curve must be a straight line.
Thermal stability test
JB/T6625-1993
Appendix B
Thermal stability test method of loading bolts
(reference)
Thermal stability test should be carried out on new loading bolts. B2 Equipment
Constant Temperature drying oven.
Operation steps
1 Clean the flat circular plate and apply low-viscosity oil to the thread of the bolt. B3.1Www.bzxZ.net
B3.2 Do not place the sample between the two flat circular plates, install the bolt, put the washer on, and tighten the nut by hand. B3.3 Install the dial gauge assembly on the bolt and tighten it by hand, and adjust the dial gauge pointer to zero (a stroke greater than 0.25mm should be left). B3.4 Use a wrench to evenly load the bolt until the dial gauge reading is 0.130±0.002mm, and record the dial gauge reading (G,). B3.5
: Remove Dial gauge assembly, place the sample assembly in a constant temperature drying oven at 1002℃, keep it for 22 hours, then take it out and cool it to room temperature in the air.
B3.6 Repeat Section B3.3.
Loosen the nut and read the dial gauge reading
Calculation and results
(G).
The error before and after the test (F) is calculated according to formula (B1): Where: F—error before and after the test:
Go—dial gauge reading before heat treatment:
G,——dial gauge reading after heat treatment.
Go-G1 ×100
F<1% is qualified. If F>1%, repeat according to Chapter B3 until F<1%. Additional Notes:
This standard is proposed and managed by the Hefei General Machinery Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Hefei General Machinery Research Institute of the Ministry of Machinery Industry and the Shanghai Asbestos Products Factory. The main drafters of this standard are Zhang Weiren, Bao Huading and Mou Ba. 4
People's Republic of China
Mechanical Industry Standard
Flexible Graphite Plate Stress Relaxation Test Method
JB/T 66251993
Published by the China Academy of Mechanical Science
Printed by the China Academy of Mechanical Science
(No. 2, Shouti South Road, Beijing
Postal Code: 100044))
Print Sheet 1/2
Word Count 8,000
Format 880×1230
First Edition in October 1993
First Printing in October 1993
Print Quantity 1-500
Price 2.00 Yuan
Mechanical Industry Standard Service Network: http:/www.JB.ac.cn699
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