Some standard content:
National Standard of the People's Republic of China
Test methods for rubber O rings
Test methods for rubber O rings1 Subject content and scope of application
GB/T5720-93
Replaces GB5720-85
This standard specifies the test methods for hardness, tensile properties, constant deformation compression permanent deformation, tensile permanent deformation, hot air aging, compression stress relaxation, liquid resistance, density, corrosion test and shrinkage of solid vulcanized O-shaped rubber seals. This standard applies to solid vulcanized O-shaped rubber seals (hereinafter referred to as O-shaped rings). 2 Reference standards
GB/T528 Determination of tensile properties of vulcanized rubber and thermoplastic rubber GB/T533 Determination of density of vulcanized rubber
GB/T1690 Test method for liquid resistance of vulcanized rubber GB2941 Standard temperature, humidity and time for environmental conditioning and testing of rubber specimens GB/T3452.2 Appearance quality inspection standard for O-rings GB/T3512 Test method for hot air aging of vulcanized rubber GB5723 Dimensional measurement of test pieces and products for vulcanized rubber testing General provisions GB/T6032 Determination of international hardness of vulcanized rubber (30~85IRHD) Micro test method GB/T7759 Determination of permanent deformation of vulcanized rubber under constant deformation compression at room temperature and high temperature GB9865 Vulcanized rubber samples and test specimen preparation GB/T13643 Determination of compression stress relaxation of vulcanized rubber or thermoplastic rubber (ring test specimen) 3 Test specimen requirements and test conditions
3.1 Test specimen requirements
3.1.1 Test specimen preparation shall be carried out in accordance with the provisions of GB9865. 3.1.2 The appearance quality of the test specimen shall comply with the provisions of GB/T3452.2. 3.2 Test conditions
The temperature and time of the test specimen environment adjustment and the test shall be carried out in accordance with the provisions of GB2941. 4 Measurement of dimensions
4.1 The tools used for dimension measurement shall comply with the relevant provisions of GB5723. 4.2 Measure the cross-sectional diameter at four points evenly distributed along the radial and axial circumference of the O-ring using a gauge with a graduation value of 0.01 mm, and take the arithmetic mean.
4.3 Measure the inner diameter at four points evenly distributed along the inner circumference of the O-ring using a tool microscope, and take the arithmetic mean. 4.4 The inner diameter can also be measured using a graded cone gauge, and the diameter difference of the graded cone steps shall not exceed 2% of the measured inner diameter. Approved by the State Administration of Technical Supervision on December 30, 1993 and implemented on October 1, 1994
5 Test procedure
5.1 Determination of hardness
5.1.1 Test instrument
GB/T 5720—93
This test is carried out on a micro hardness tester, and the hardness tester shall comply with the relevant provisions of GB/T6032. 5.1.2 Test specimens
5.1.2.1 The specifications of the standard test specimens shall comply with the provisions of Appendix A1. 5.1.2.2 For O-rings with a cross-sectional diameter of more than 6 mm or an inner diameter of more than 30 mm, a segment may be cut for measurement, and the result cannot be compared with the standard test specimen result.
5.1.3 Test steps
Perform the test steps of GB/T6032.
5.1.4 Representation of test results
The test results are 3, take the median, and round up the integer. 5.2 Determination of tensile properties
5.2.1 Test instrument
5.2.1.1 This test is carried out on a tensile machine, which shall comply with the relevant provisions of GB/T528. The tensile machine shall have a guide rack device and a device for measuring the elongation of the specimen.
5.2.1.2 Test fixture
The test fixture consists of two upper and lower shaft wheels with ball bearings of at least 12 mm diameter. When the two wheels are close to each other, the center distance is within 25 mm. The lower fixture is equipped with a gear transmission device, which should be engaged with the guide rack on the tensile machine during the test. The linear specimen fixture adopts the universal tensile test fixture, but it is necessary to ensure that the specimen is constantly in the clamping position during the test. 5.2.2 Specimens
5.2.2.1 The standard specimen shall comply with the provisions of Appendix A2. 5.2.2.2 O-rings of other sizes with an inner diameter greater than 40 mm, or segments cut from O-rings (linear specimens with a length of not less than 120 mm) may be used for measurement, and the results cannot be compared with the results of standard specimens. 5.2.3 Test procedures
5.2.3.1 Measure the cross-sectional diameter and inner diameter of the specimen in accordance with the provisions of Chapter 4. If it is a linear specimen, proceed according to the methods in Articles 4.2.4 and 4.2.5 of GB/T528. The spacing between the markings on the working part is 25mm. 5.2.3.2 Put the O-ring on the shaft wheels of the upper and lower clamps as close as possible so that the specimen is not subjected to tensile stress, connect the elongation measurement system, and adjust the zero point (that is, determine the center distance S of the two shaft wheels when the elongation of the inner circumference of the O-ring is equal to zero), and calculate the S value by formula (2). 5.2.3.3 Start the machine to stretch the specimen at a speed of 500 ± 50mm/min, and record the load when the specimen is stretched to the specified elongation, the load when it is broken and the elongation
5.2.3.4 If the specimen is a linear single-strand specimen, perform the tensile test according to the steps in Article 6.1 of GB/T528. 5.2.4 Calculation of test results
5.2.4.1 The center distance between the two axle wheels is calculated according to formula (1): {(eCo/100) + C. -- GJ
Wherein, —
the distance between the centers of the two axle wheels, mm;
elongation of the specimen, %;
(, ()-shaped ring initial inner circumference, mm; G-circumference of a axle wheel, mm.
When e=0 in formula (1), we get
(C. -- GJ
G)
GB/T5720—93
5.2.4.2 The tensile stress and tensile strength are calculated according to formula (3) and formula (4): round ring specimen:
straight specimen:
tensile stress or tensile strength, MPa;
F—load on the specimen, N;
cross-sectional area of the specimen, mm;
cross-sectional diameter of the specimen, mm.
5.2.4.3 The tensile elongation is calculated according to formula (5) and formula (6): a.
where: E
round ring specimen:
tensile elongation, %;
2A—1.57d2
E= 2S +GC.
()-shaped ring is torn off when the center distance between the two shaft wheels, mm; -The circumference of a shaft wheel, mm;
(:\0)-shaped sealing ring initial inner circumference, mm. h.
Linear test sample:
Formula: E-
Elongation at break, %;
L- Lo× 100
The distance between the two markings when the specimen is broken, mm; the original distance between the two markings of the specimen, mm. 5.2.5 Representation of test results
(3)
(6)
There are 5 test results. The test result is the median of the calculated results. The elongation at break is rounded to an integer, and the tensile stress and tensile strength are rounded to one decimal place.
5.3 Hot air aging test
5.3.1 Test apparatus
The aging chamber shall comply with the provisions of Chapter 2 of GB/T3512. 5.3.2 Test specimens
The standard specimens shall be in accordance with the provisions of Appendix A3, and the non-standard specimens shall be the same as 5.2.2.2. 5.3.3 Test steps
5.3.3.1 Tensile stress, tensile strength and elongation at break before and after aging The determination of hardness shall be carried out according to the steps in 5.2.3. 5.3.3.2 The determination of hardness before and after aging shall be carried out according to the steps in 5.1.3. 5.3.3.3 Place the specimen in an aging box at the specified temperature and start timing. 5.3.3.4 After the specified time is reached, immediately remove the specimen from the aging box and place it at room temperature for at least 16 hours, but not more than 6 days. 5.3.4 Calculation of test results
5.3.4.1 The percentage change in tensile strength shall be calculated according to formula (7): AT
武中：A7
Percentage change in tensile strength of the specimen after hot air aging, %; T\-Tensile strength of the specimen before aging, MPa;·(7)
GB/T5720-93
Tensile strength of the specimen after hot air aging, MPa. 5.3.4.2 The percentage change in elongation at break shall be calculated according to formula (8): E, - E.
Wherein: AE, -
percentage change in the tensile elongation of the specimen after hot air aging, %; tensile elongation of the specimen before aging, %;
E, - tensile elongation of the specimen after hot air aging, %. 5.3.4.3 The test result of hardness is expressed as the change in hardness, calculated according to formula (9): AH, = H,H.
Wherein: AH
Change in hardness after hot air aging, IRHD; Hardness of the specimen after hot air aging, IRHD; H,
Hardness of the specimen before aging, IRHD.
5.3.5 Representation of test results
5.3.5.1 The results of the aging test of tensile strength and elongation at break are expressed as the results calculated by formula (7) and formula (8), and the integer is rounded. 5.3.5.2 The results of the hardness aging test are expressed as the results calculated by formula (9), and the integer is rounded. 5.4 Determination of permanent deformation of constant deformation compression 5.4.1 Test apparatus
5.4.1.1 The compression fixture is a circular plate stacking structure, as shown in the figure below. Compression fixture structure diagram
(8)
5.4.1.2 The height of the limiter is 75% of the diameter of the specimen section, and its tolerance is + 0.05mm. 5.4.1.3 Immersion container for compression set test in liquid - generally steel seal, but other materials can also be used. Sealed containers that are resistant to high temperature, liquid and pressure. The size should be suitable for accommodating compression fixtures, sufficient test liquid and easy operation. 5.4.1.4 Heating device is aging box, water bath or oil bath. 5.4.2 Test specimen
5.4.2.1 Standard test specimen shall comply with the provisions of Appendix A4. 5.4.2.2 O-rings or their fragments of other specifications may be used for measurement, and the results cannot be compared with the results of standard test specimens. 5.4.3 Test liquid
5.4.3.1 The amount of test liquid should ensure that the test fixture is always submerged below 15mm of the liquid surface during the test. 5.4.3.2 The test liquid can only be used once, and samples of different formulations shall not be tested in the same container at the same time. 5.4.4 Test steps
GB/T 5720-93
5.4.4.1 Measure the axial cross-sectional diameter of the U-shaped ring or its fragment according to 4.2. 5.4.4.2 Place the U-shaped ring or its fragments between the pressure plates of the fixture in sequence. The specimen and the limiter do not contact each other. 5.4.4.3 Compress the fixture with the specimen so that the pressure plate and the limiter are in close contact, and tighten the nut. 5.4.4.4 If a liquid resistance test is performed, place the fixture with the specimen at room temperature for 30 minutes, then place it in a container containing the test liquid, place the container in an aging box at a specified temperature, and start timing. 5.4.4.5 If a hot air aging test is performed, place the fixture with the specimen at room temperature for 30 minutes, then place it in an aging box at a specified temperature, and start timing.
5.4.4.6 When the specified time is reached, remove the immersion container or fixture from the aging box. a. For high temperature non-volatile liquids, if the container is taken out, it needs to be cooled at room temperature for 30 minutes, then open the container and take out the clamp, then loosen it and take out the sample for washing. The washing time of each sample shall not exceed 30 minutes. The sample shall be placed on a flat wooden board and allowed to recover for 30 minutes at room temperature. For room temperature volatile liquids, after the specified time, the clamp shall be taken out from the container and immediately loosened, and the sample shall be taken out and placed on a flat wooden board. It shall be allowed to recover for 30 minutes at room temperature. For high temperature air, if the container is taken out, the clamp shall be immediately loosened, and the sample shall be taken out and placed on a flat wooden board and allowed to recover for 30 minutes at room temperature. Then, measure the cross-sectional diameter of the () ring or its segment according to 1.2. 5.4.5 Calculation of test results
The compression set is calculated according to formula (10):
d, de
d, - hs
Wherein: B, compression set rate of the sample after heat-tight air aging or liquid immersion,%; d, initial axial section diameter of the sample, mm; d. True axial section diameter of the sample after recovery. mm; h, height of the limiter, mm.
5.4.6 Representation of test results
There are 3 test results. The arithmetic mean of the calculated results is taken as the test result, and the integer is rounded. 5.5 Determination of tensile permanent deformation
5.5.1 Test group
5.5.1.1 The standard specimen for tensile permanent deformation shall comply with the provisions of Appendix A2. 5.5.1.2 Standard specimens shall be arranged in the same way as in 5.2.2.2. 5.5.2 Test apparatus
This test may be carried out on any of the following devices: 5.5.2.1 A tensile testing machine in accordance with the provisions of 5.2.1; 5.5.2.2 A graded cone with the required 100% elongation step; 5.5.2.3 Any device capable of mounting the O-ring on two shaft wheels capable of maintaining a certain center distance. 5.5.3 Test procedure
+*..( 10 )
Use a 1. graded cone to measure the inner diameter of the O-ring. Stretch the O-ring specimen to 100% and keep it at this strain for 10 minutes. Then release the specimen and allow it to recover for 10 minutes. Then use a 4,4 graded cone to measure the inner diameter of the specimen. 5.5.4 Calculation and expression of test latitude
5.5.4.1 The tensile permanent deformation is calculated according to formula (11): Where B. Tensile permanent deformation rate, %
D=D×100
D, —Inner diameter of the test specimen after the test, mm#
D Initial inner diameter of the test specimen, mm.
GB/T 5720—93
5.5.4.2 The test results are 5, and the median of the calculated results is taken as the test result, and the integer is rounded. 5.5.5 The tensile permanent deformation test of the linear test specimen is carried out according to GB/T528. 5.6 Corrosion test
5.6.1 Test specimen
5.6.1.1 Standard test specimen shall comply with the provisions of Appendix A4. 5.6.1.2 Other specifications of ()-shaped rings or segments (such as 38mm in length) may be used, but the results cannot be compared with those of standard specimens.
5.6.2 Test apparatus
5.6.2.1 The test apparatus consists of any corrosion-resistant, sealed container with suitable working dimensions. Note… Laboratory desiccators are generally used.
5.6.2.2 Unless otherwise specified, the test fixture plate should be made of 45# steel, nickel-plated (0.0002~~0.004mm thick), with a roughness R. of 0.16~~0.25um. The size should be suitable for clamping the specimen and being placed in the container of 5.6.2.1. 5.6.2.3 A mixture of 85% distilled water and 15% glycerol by volume is injected into the container of 5.6.2.1 to maintain a relative humidity of 100%. The depth of the mixture shall be at least 20% of the depth of the container. 5.6.2.4 Support the fixture in the container with a corrosion-resistant shelf so that it is close to but not in contact with the mixture. 5.6.3 Test Procedure
5.6.3.1 Clean the test plate with anhydrous ethanol or other suitable solvent and dry it. 5.6.3.2 Measure the axial cross-sectional diameter of the specimen using the gage in 4.2. 5.6.3.3 Remove the cover of the desiccator and place the specimen and the test platen in the container without covering for 1 hour. 5.6.3.4 Place the specimen in the test fixture and apply pressure to produce a 15% deformation in the axial cross-sectional diameter of the specimen and maintain this deformation.
Place the assembled fixture on a piece of flat glass and then place the glass plate on the shelf in the test container. Cover the container with the cover to maintain the seal. 5.6.3.5
5.6.3.6 Keep the container at 23±2°C for 96h. Note: Other test temperatures may be used, but they should be stated in the test report. 5.6.3.7 Take out the sample, use filter paper to absorb the water stains on the test plate, and observe the traces left by the sample on the test plate with the naked eye. 5.6.3.8 The test results are used to evaluate the corrosion level using no corrosion, moderate corrosion (visible light-colored marks) and severe corrosion (dark spots or rust spots).
5.7 Liquid resistance test
5.7.1 Sample
5.7.1.1 The standard sample shall comply with the provisions of Appendix A5. 5.7.1.2 If the size of the sample () ring is too large to fit into the immersion device, it can be cut into pieces of 90±2mm in length as the sample. The results cannot be compared with those of the standard sample. 5.7.2 Capacity of test liquid
5.7.2.1 The volume of the liquid shall not be less than 15 times the total volume of the specimen, and ensure that the specimen is always completely immersed below 15 mm of the liquid surface during the test.
5.7.2.2 The test liquid shall be used only once, and specimens of different formulations shall not be immersed in the same liquid at the same time. 5.7.3 Test steps
5.7.3.1 The mass and volume change tests shall be carried out in accordance with the steps of GB/T1690. 5.7.3.2 The tensile properties test before and after immersion shall be carried out in accordance with the steps of Article 5.2.3. The hardness test after immersion shall be carried out in accordance with the provisions of 5.1.3. 5.7.4 Calculation of test results
5.7.4.1 The percentage change in mass domain is calculated according to formula (12): GB/T5720--93
wherein: percentage change in mass, %,
m, mass of the sample in air before bubbling
- mass of the sample in air after bubbling, name. m? mi
5.7.4.2 The percentage change in volume is calculated according to formula (13): (ms = m) - (ml = ma) × 100
Wu Zhong: AV
Percentage change in volume, %:
The mass of the sample in water before soaking, nom:, the mass of the sample in water after soaking, nom, mm
Formula (12)
m, - m2
5.7.4.3 The percentage change in tensile strength is calculated according to formula (14): AT
Formula: AT is the percentage change in tensile strength after the sample is soaked in liquid, %, T is the tensile strength of the sample before soaking, MPa; T.-the tensile strength of the sample after soaking, MPa. 5.7.4.4 The percentage change of elongation at break shall be calculated according to formula (15): AE, ΔE, percentage change of elongation at break after the sample is soaked in liquid, %; Eu, elongation at break of the sample before soaking, %; elongation at break of the sample after soaking, %.
5.7.4.5 The change of hardness shall be calculated according to formula (16): A2-H,-H.
Wherein: AI, change in hardness of the sample after soaking in liquid, IRHD; H, hardness of the sample before soaking, IRHD;
H, hardness of the sample after soaking in liquid, RHD. 5.7.5 Representation of test results
5.7.5.1 Change in mass and volume
If there are three measurement results, the test result shall be the arithmetic mean of the results calculated according to formula (12) or formula (13), and the decimal point shall be rounded. 5.7.5.2 Tensile properties
The test results of the liquid resistance test shall be expressed as the result calculated by formula (14) or formula (15), and the median shall be taken as the integer. 5.7.5.3 Hardness change
The hardness change of the sample after being soaked in liquid shall be expressed as the result calculated by formula (16), and the median shall be taken as the integer. 5.8 Determination of density
5.8.1 Test instrument
The test instrument shall comply with the relevant provisions of G3/T533. 5.8.2 Test specimen
(12)
(13)
.(14)
(15)
5.8.2.1 Specifications of standard test specimens shall be in accordance with the provisions of Article A5. 5.8.2.2 O-rings or their fragments of any specifications shall be used, and their mass shall not be less than 0.5g. If it is less than 0.5g, several O-rings or fragments with a total mass of more than 0.5g may be used as specimens. The results cannot be compared with those of standard specimens. 5.8.3 Test procedures
The test procedures shall be carried out in accordance with the relevant provisions of GB/T533. 5.8.4 Calculation of test results
5.8.4.1 The density of the sample at the test temperature is calculated according to formula (17): PR
When using a sinker, it is calculated according to formula (18):
mi+ms-mg\
Wherein, Pk is the density of the sample, mg/m2,
m,--the mass of the sample in air, g; mz is the mass of the sample in water, g;
m,--the mass of the sinker in water, g
ms--the mass of the sample and the sinker in water, g; P. is the density of distilled water at the test temperature, mg/m2. 5.8.5 Representation of test results
There are 3 measurement results, and the test result is the median of the calculated results, rounded to two decimal places. 5.9 Determination of shrinkage
5.9.1 Test instrument
A large tool microscope is used to measure the geometric dimensions of the mold and the O-ring. (17)
(18)
5.9.2 Test specimens
Qualified test specimens shall be prepared using qualified molds for manufacturing O-rings with an inner diameter of 25±0.22mm and a cross-sectional diameter of 3.55±0.10mm. Test specimens may also be prepared using molds of other sizes. 5.9.3 Test procedures
5.9.3.1 At least four locations evenly distributed along the O-ring, use a tool microscope to measure the inner diameter and radial cross-sectional diameter, and take the arithmetic averages.
5.9.3.2 At at least four locations evenly distributed along the corresponding mold cavity, use a tool microscope to measure the inner diameter and radial width of the two halves of the mold cavity, and take the average values of the inner diameter and radial width of the two halves of the mold cavity as the inner diameter and radial cross-sectional diameter of the cavity, respectively. 5.9.4 Calculation of test results
5.9.4.1 The shrinkage rate of inner diameter shall be calculated according to formula (19): Where: K, — shrinkage rate of inner diameter of O-ring, %; D. — inner diameter of cavity, mm;
inner diameter of O-ring, mm,
Ki Do= D
5.9.4.2 The shrinkage rate of radial section diameter shall be calculated according to formula (20): K,
Where: K2-
× 100
d. d?
-Shrinkage rate of radial section diameter of O-ring, %; d. —diameter of radial section of cavity, mm;
d, diameter of radial section of O-ring, mm.
5.9.5 Expression of test results
(20)
GB/T5720-93
The test results are 3, and the test result is the average of the calculated results, with two decimal places. Determination of compressive stress relaxation
Carry out in accordance with GB/T13643
Test report
Name or code of test sample;
Name or number of standard based on which the test is conducted; temperature of test room;
Test conditions;
Specimen specifications;
Test results;
Tester, reviewer;
Test date.
GB/T 5720-93
Appendix A
Standard specimens of O-shaped rubber sealing rings
(Supplement)
This appendix applies to quality assessment and comparative tests. A1 The inner diameter of the standard specimen for hardness test and compression stress relaxation test is 14±0.17mm, the cross-sectional diameter is 2.65±0.09mm, and the number of specimens is 3. A2 The inner diameter of the standard specimen for tensile properties and tensile permanent deformation test is 40±0.30mm, and the cross-sectional diameter is 3.55±0.10mm. The number of specimens is 5. A3 The specification of the standard specimen for hot air aging test is the same as A2. A4 The inner diameter of the standard specimen for constant deformation compression permanent deformation test is 25±0.22mm, the cross-sectional diameter is 3.55±0.10mm, and the number of specimens is 3. A5 The specification of the standard specimen for liquid resistance test and density test is the same as A4, and the number of specimens is 3. A6 The specification of the standard specimen for corrosion test is the same as A4, and the number of specimens is 2. Additional remarks: This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Yuan Zhengcai, Jin Daixin, Su Guirong and Li Zongqi. This standard refers to the American Society for Testing and Materials standard ASTMD1414-1990 "Standard Test Method for O-Ring Rubber Seals".
Wherein: AI is the change in hardness of the specimen after immersion in liquid, IRHD; H is the hardness of the specimen before immersion, IRHD;
H is the hardness of the specimen after immersion in liquid, RHD. 5.7.5 Expression of test results
5.7.5.1 Change in mass and volume
There are 3 measurement results. The test result is the arithmetic mean of the results calculated according to formula (12) or formula (13), and the decimal point is rounded. 5.7.5.2 Tensile properties
The test result of the liquid resistance test is expressed according to the result calculated according to formula (14) or formula (15), and the integer of the median is rounded. 5.7.5.3 Hardness change
The change in hardness of the specimen after immersion in liquid is expressed according to the result calculated according to formula (16), and the integer of the median is rounded. 5.8 Determination of density
5.8.1 Test instrument
The test instrument shall comply with the relevant provisions of G3/T533. 5.8.2 Test specimen
(12)
(13)
.(14)
(15)
5.8.2.1 Specifications of standard test specimens shall be in accordance with the provisions of Article A5. 5.8.2.2 O-rings or their fragments of any specifications shall be used, and their mass shall not be less than 0.5g. If it is less than 0.5g, several O-rings or fragments with a total mass of more than 0.5g may be used as specimens. The results cannot be compared with those of standard specimens. 5.8.3 Test procedures
The test procedures shall be carried out in accordance with the relevant provisions of GB/T533. 5.8.4 Calculation of test results
5.8.4.1 The density of the sample at the test temperature is calculated according to formula (17): PR
When using a sinker, it is calculated according to formula (18):
mi+ms-mg\
Wherein, Pk is the density of the sample, mg/m2,
m,--the mass of the sample in air, g; mz is the mass of the sample in water, g;
m,--the mass of the sinker in water, g
ms--the mass of the sample and the sinker in water, g; P. is the density of distilled water at the test temperature, mg/m2. 5.8.5 Representation of test results
There are 3 measurement results, and the test result is the median of the calculated results, rounded to two decimal places. 5.9 Determination of shrinkage
5.9.1 Test instrument
A large tool microscope is used to measure the geometric dimensions of the mold and the O-ring. (17)
(18)
5.9.2 Test specimens
Qualified test specimens shall be prepared using qualified molds for manufacturing O-rings with an inner diameter of 25±0.22mm and a cross-sectional diameter of 3.55±0.10mm. Test specimens may also be prepared using molds of other sizes. 5.9.3 Test procedures
5.9.3.1 At least four locations evenly distributed along the O-ring, use a tool microscope to measure the inner diameter and radial cross-sectional diameter, and take the arithmetic averages.
5.9.3.2 At at least four locations evenly distributed along the corresponding mold cavity, use a tool microscope to measure the inner diameter and radial width of the two halves of the mold cavity, and take the average values of the inner diameter and radial width of the two halves of the mold cavity as the inner diameter and radial cross-sectional diameter of the cavity, respectively. 5.9.4 Calculation of test results
5.9.4.1 The shrinkage rate of inner diameter shall be calculated according to formula (19): Where: K, — shrinkage rate of inner diameter of O-ring, %; D. — inner diameter of cavity, mm;
inner diameter of O-ring, mm,
Ki Do= D
5.9.4.2 The shrinkage rate of radial section diameter shall be calculated according to formula (20): K, bzxZ.net
Where: K2-
× 100
d. d?
-Shrinkage rate of radial section diameter of O-ring, %; d. —diameter of radial section of cavity, mm;
d, diameter of radial section of O-ring, mm.
5.9.5 Expression of test results
(20)
GB/T5720-93
The test results are 3, and the test result is the average of the calculated results, with two decimal places. Determination of compressive stress relaxation
Carry out in accordance with GB/T13643
Test report
Name or code of test sample;
Name or number of standard based on which the test is conducted; temperature of test room;
Test conditions;
Specimen specifications;
Test results;
Tester, reviewer;
Test date.
GB/T 5720-93
Appendix A
Standard specimens of O-shaped rubber sealing rings
(Supplement)
This appendix applies to quality assessment and comparative tests. A1 The inner diameter of the standard specimen for hardness test and compression stress relaxation test is 14±0.17mm, the cross-sectional diameter is 2.65±0.09mm, and the number of specimens is 3. A2 The inner diameter of the standard specimen for tensile properties and tensile permanent deformation test is 40±0.30mm, and the cross-sectional diameter is 3.55±0.10mm. The number of specimens is 5. A3 The specification of the standard specimen for hot air aging test is the same as A2. A4 The inner diameter of the standard specimen for constant deformation compression permanent deformation test is 25±0.22mm, the cross-sectional diameter is 3.55±0.10mm, and the number of specimens is 3. A5 The specification of the standard specimen for liquid resistance test and density test is the same as A4, and the number of specimens is 3. A6 The specification of the standard specimen for corrosion test is the same as A4, and the number of specimens is 2. Additional remarks: This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Yuan Zhengcai, Jin Daixin, Su Guirong and Li Zongqi. This standard refers to the American Society for Testing and Materials standard ASTMD1414-1990 "Standard Test Method for O-Ring Rubber Seals".
Wherein: AI is the change in hardness of the specimen after immersion in liquid, IRHD; H is the hardness of the specimen before immersion, IRHD;
H is the hardness of the specimen after immersion in liquid, RHD. 5.7.5 Expression of test results
5.7.5.1 Change in mass and volume
There are 3 measurement results. The test result is the arithmetic mean of the results calculated according to formula (12) or formula (13), and the decimal point is rounded. 5.7.5.2 Tensile properties
The test result of the liquid resistance test is expressed according to the result calculated according to formula (14) or formula (15), and the integer of the median is rounded. 5.7.5.3 Hardness change
The change in hardness of the specimen after immersion in liquid is expressed according to the result calculated according to formula (16), and the integer of the median is rounded. 5.8 Determination of density
5.8.1 Test instrument
The test instrument shall comply with the relevant provisions of G3/T533. 5.8.2 Test specimen
(12)
(13)
.(14)
(15)
5.8.2.1 Specifications of standard test specimens shall be in accordance with the provisions of Article A5. 5.8.2.2 O-rings or their fragments of any specifications shall be used, and their mass shall not be less than 0.5g. If it is less than 0.5g, several O-rings or fragments with a total mass of more than 0.5g may be used as specimens. The results cannot be compared with those of standard specimens. 5.8.3 Test procedures
The test procedures shall be carried out in accordance with the relevant provisions of GB/T533. 5.8.4 Calculation of test results
5.8.4.1 The density of the sample at the test temperature is calculated according to formula (17): PR
When using a sinker, it is calculated according to formula (18):
mi+ms-mg\
Wherein, Pk is the density of the sample, mg/m2,
m,--the mass of the sample in air, g; mz is the mass of the sample in water, g;
m,--the mass of the sinker in water, g
ms--the mass of the sample and the sinker in water, g; P. is the density of distilled water at the test temperature, mg/m2. 5.8.5 Representation of test results
There are 3 measurement results, and the test result is the median of the calculated results, rounded to two decimal places. 5.9 Determination of shrinkage
5.9.1 Test instrument
A large tool microscope is used to measure the geometric dimensions of the mold and the O-ring. (17)
(18)
5.9.2 Test specimens
Qualified test specimens shall be prepared using qualified molds for manufacturing O-rings with an inner diameter of 25±0.22mm and a cross-sectional diameter of 3.55±0.10mm. Test specimens may also be prepared using molds of other sizes. 5.9.3 Test procedures
5.9.3.1 At least four locations evenly distributed along the O-ring, use a tool microscope to measure the inner diameter and radial cross-sectional diameter, and take the arithmetic averages.
5.9.3.2 At at least four locations evenly distributed along the corresponding mold cavity, use a tool microscope to measure the inner diameter and radial width of the two halves of the mold cavity, and take the average values of the inner diameter and radial width of the two halves of the mold cavity as the inner diameter and radial cross-sectional diameter of the cavity, respectively. 5.9.4 Calculation of test results
5.9.4.1 The shrinkage rate of inner diameter shall be calculated according to formula (19): Where: K, — shrinkage rate of inner diameter of O-ring, %; D. — inner diameter of cavity, mm;
inner diameter of O-ring, mm,
Ki Do= D
5.9.4.2 The shrinkage rate of radial section diameter shall be calculated according to formula (20): K,
Where: K2-
× 100
d. d?
-Shrinkage rate of radial section diameter of O-ring, %; d. —diameter of radial section of cavity, mm;
d, diameter of radial section of O-ring, mm.
5.9.5 Expression of test results
(20)
GB/T5720-93
The test results are 3, and the test result is the average of the calculated results, with two decimal places. Determination of compressive stress relaxation
Carry out in accordance with GB/T13643
Test report
Name or code of test sample;
Name or number of standard based on which the test is conducted; temperature of test room;
Test conditions;
Specimen specifications;
Test results;
Tester, reviewer;
Test date.
GB/T 5720-93
Appendix A
Standard specimens of O-shaped rubber sealing rings
(Supplement)
This appendix applies to quality assessment and comparative tests. A1 The inner diameter of the standard specimen for hardness test and compression stress relaxation test is 14±0.17mm, the cross-sectional diameter is 2.65±0.09mm, and the number of specimens is 3. A2 The inner diameter of the standard specimen for tensile properties and tensile permanent deformation test is 40±0.30mm, and the cross-sectional diameter is 3.55±0.10mm. The number of specimens is 5. A3 The specification of the standard specimen for hot air aging test is the same as A2. A4 The inner diameter of the standard specimen for constant deformation compression permanent deformation test is 25±0.22mm, the cross-sectional diameter is 3.55±0.10mm, and the number of specimens is 3. A5 The specification of the standard specimen for liquid resistance test and density test is the same as A4, and the number of specimens is 3. A6 The specification of the standard specimen for corrosion test is the same as A4, and the number of specimens is 2. Additional remarks: This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Yuan Zhengcai, Jin Daixin, Su Guirong and Li Zongqi. This standard refers to the American Society for Testing and Materials standard ASTMD1414-1990 "Standard Test Method for O-Ring Rubber Seals".1 At least four positions evenly distributed along the O-ring, use a tool microscope to measure the inner diameter and radial cross-sectional diameter, and take the arithmetic mean.
5.9.3.2 At at least four positions evenly distributed along the corresponding mold cavity, use a tool microscope to measure the inner diameter and radial width of the two halves of the mold cavity, and take the average value of the inner diameter and radial width of the two halves of the mold cavity as the inner diameter and radial cross-sectional diameter of the cavity, respectively. 5.9.4 Calculation of test results
5.9.4.1 The inner diameter shrinkage rate is calculated according to formula (19): Where: K, —(O-ring inner diameter shrinkage rate, %; D. --Inner diameter of the mold cavity, mm;
Inner diameter of the O-ring, mm,
Ki Do= D
5.9.4.2 The radial section diameter shrinkage rate is calculated according to formula (20): K,
Wherein: K2-
× 100
d. d?
-O-ring radial section diameter shrinkage rate, %; d. --Radial section diameter of the mold cavity, mm;
d, O-ring radial section diameter, mm.
5.9.5 Representation of test results
(20)
GB/T5720-93
The test results are 3, and the test result is the average of the calculated results, rounded to two decimal places. Determination of compressive stress relaxation
Carry out in accordance with GB/T13643
Test report
Name or code of test sample;
Name or number of standard based on which the test is conducted; Test room temperature;
Test conditions;
Specimen specifications;
Test results;
Tester, reviewer;
Test date.
GB/T 5720-93
Appendix A
Standard specimen of O-shaped rubber sealing ring
(Supplement)
This appendix is applicable to quality assessment and comparative tests. A1 Specimens for hardness determination and compressive stress relaxation determination The inner diameter of the standard specimen is 14±0.17mm, the cross-sectional diameter is 2.65±0.09mm, and the number of specimens is 3. A2 The inner diameter of the standard specimen for tensile properties and tensile permanent deformation is 40±0.30mm, and the cross-sectional diameter is 3.55±0.10mm. The number of specimens is 5. A3 The specification of the standard specimen for hot air aging test is the same as A2. A4 The inner diameter of the standard specimen for constant deformation compression permanent deformation test is 25±0.22mm, and the cross-sectional diameter is 3.55±0.10mm. The number of specimens is 3. A5 The specification of the standard specimen for liquid resistance test and density determination is the same as A4, and the number of specimens is 3. A6 The specification of the standard specimen for corrosion test is the same as A4, and the number of specimens is 2. Additional remarks: This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Yuan Zhengcai, Jin Daixin, Su Guirong and Li Zongqi. This standard adopts the American Society for Testing and Materials standard ASTMD1414-1990 "Standard Test Method for O-Ring Rubber Seals".1 At least four positions evenly distributed along the O-ring, use a tool microscope to measure the inner diameter and radial cross-sectional diameter, and take the arithmetic mean.
5.9.3.2 At at least four positions evenly distributed along the corresponding mold cavity, use a tool microscope to measure the inner diameter and radial width of the two halves of the mold cavity, and take the average value of the inner diameter and radial width of the two halves of the mold cavity as the inner diameter and radial cross-sectional diameter of the cavity, respectively. 5.9.4 Calculation of test results
5.9.4.1 The inner diameter shrinkage rate is calculated according to formula (19): Where: K, —(O-ring inner diameter shrinkage rate, %; D. --Inner diameter of the mold cavity, mm;
Inner diameter of the O-ring, mm,
Ki Do= D
5.9.4.2 The radial section diameter shrinkage rate is calculated according to formula (20): K,
Wherein: K2-
× 100
d. d?
-O-ring radial section diameter shrinkage rate, %; d. --Radial section diameter of the mold cavity, mm;
d, O-ring radial section diameter, mm.
5.9.5 Representation of test results
(20)
GB/T5720-93
The test results are 3, and the test result is the average of the calculated results, rounded to two decimal places. Determination of compressive stress relaxation
Carry out in accordance with GB/T13643
Test report
Name or code of test sample;
Name or number of standard based on which the test is conducted; Test room temperature;
Test conditions;
Specimen specifications;
Test results;
Tester, reviewer;
Test date.
GB/T 5720-93
Appendix A
Standard specimen of O-shaped rubber sealing ring
(Supplement)
This appendix is applicable to quality assessment and comparative tests. A1 Specimens for hardness determination and compressive stress relaxation determination The inner diameter of the standard specimen is 14±0.17mm, the cross-sectional diameter is 2.65±0.09mm, and the number of specimens is 3. A2 The inner diameter of the standard specimen for tensile properties and tensile permanent deformation is 40±0.30mm, and the cross-sectional diameter is 3.55±0.10mm. The number of specimens is 5. A3 The specification of the standard specimen for hot air aging test is the same as A2. A4 The inner diameter of the standard specimen for constant deformation compression permanent deformation test is 25±0.22mm, and the cross-sectional diameter is 3.55±0.10mm. The number of specimens is 3. A5 The specification of the standard specimen for liquid resistance test and density determination is the same as A4, and the number of specimens is 3. A6 The specification of the standard specimen for corrosion test is the same as A4, and the number of specimens is 2. Additional remarks: This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. This standard was drafted by the Northwest Rubber Industry Products Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Yuan Zhengcai, Jin Daixin, Su Guirong and Li Zongqi. This standard adopts the American Society for Testing and Materials standard ASTMD1414-1990 "Standard Test Method for O-Ring Rubber Seals".
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