This standard specifies the following geometrical tolerances for molded and extruded compact rubber products, including such products with metal frames: - Flatness tolerance; - Parallelism tolerance; - Perpendicularity tolerance; - Coaxiality tolerance; - Position tolerance. The tolerances specified in this standard apply to vulcanized rubber products and also to products made of thermoplastic rubber. GB/T 3672.2-2002 Tolerances for rubber products Part 2: Geometrical tolerances GB/T3672.2-2002 Standard download decompression password: www.bzxz.net

GB/T3672.2
2—2002
This standard is equivalent to ISO3302-2:1998 "Tolerances for rubber products - Part 2: Geometrical tolerances". This standard is a supplement to the original GB/T3672 content, and together with GB/T3672.1---2002 "Tolerances for rubber products - Part 1: Dimensional tolerances", it constitutes the tolerance standard for rubber products. This standard was proposed by the State Administration of Petroleum and Chemical Industry, and this standard is under the jurisdiction of the Sealing Products Sub-Technical Committee of the National Technical Committee for Standardization of Rubber and Rubber Products. This standard was drafted by the Northwest Rubber and Plastic Research and Design Institute, and the participating units include Guizhou Dazhong Rubber Co., Ltd. and Shanghai Rubber Products Factory No. 1.
The drafters of this standard are: Gao Jingru, Cao Yuanli, Wang Guixian, and Liang Caiming. 21
GB/T 3672. 2-2002
ISOForeword
The International Organization for Standardization (ISO) is a worldwide organization of national standardization bodies (ISO members). The work of preparing international standards is usually carried out by ISO technical committees. Any member body interested in a project for which a technical committee has been established has the right to participate in the committee. Governmental or non-governmental organizations in contact with ISO also have the right to participate in this work. ISO maintains close contact with the International Electrotechnical Organization (IEC) in all aspects of electrotechnical standardization.
Draft international standards adopted by technical committees are circulated to member bodies for voting. At least 75% of the members must participate when published as international standards.
International Standard ISO3302-2 was prepared by ISO/TC45 Rubber and Rubber Products Technical Committee, SC4 Miscellaneous Products Subcommittee. This version of ISO 3302 comprises the following parts under the general title Rubber - Tolerances on products: Part 1: Dimensional tolerances Part 2: Geometrical tolerances 1 Scope National Standard of the People's Republic of China Tolerances on rubber products Part 2: Geometrical tolerances Rubber----Tolerances of products-Part 2:geometrical tolerances GB/T 3672.2—2002 IDT ISO 3301-2:1998 This standard specifies the following geometrical tolerances for moulded and extruded compact rubber products, including those with metal skeletons: flatness tolerance; parallelism tolerance; perpendicularity tolerance; coaxiality tolerance; position tolerance.
The tolerances specified in this standard apply to vulcanized rubber products and also to products made of thermoplastic rubber. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T29411991 Standard temperature, humidity and time for environmental conditioning and testing of rubber specimens (eqvISO471:1995) GB/T5723--1993 Determination of dimensions of specimens and products for testing vulcanized rubber or thermoplastic rubber (eqvISO4648:1991) Determination of hardness of vulcanized rubber or thermoplastic rubber (10~100IRHD) (idtIS048:i994) GB/T 6031--1998 Geometric tolerances Overview, definitions, symbols and 1S()1101:1983 Technical drawings
Representation!
ISO) 2230: 1973
3 Tolerance Classification
Guide to Storage of Vulcanized Rubber 2
This standard specifies the following three tolerance levels: P precision;
M intermediate;
N non-strict grade
The required tolerance level should be determined according to the use requirements. M and P grades require more processing procedures and a certain degree of finishing, such as grinding and polishing.
Not all cross-sectional tolerances of molded and extruded products of any structure can be represented by graphical methods. The tolerances shown in Figures 1 to 6 1) The original text of this standard can be found in the Standard Library of the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, and is under the jurisdiction of the Mechanical Standardization Research Institute of the Ministry of Machinery and Electronics. 2) The original text of this standard can be found in the Standard Library of the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, and is under the jurisdiction of the National Technical Committee for Standardization of Rubber and Rubber Products. Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on May 29, 2002, and implemented on December 1, 2002
It should be understood that these are typical examples only.
GB/T 3672. 2—2002
Chapters 5 to 7 of ISO1101-1983 give legends and explanations of tolerance boxes and tolerance zones. It is important to note that the smallest tolerances do not apply to all hardness rubber products. Products made of low-hardness rubber generally have wider tolerances than high-hardness vulcanized rubber products.
4 Measurement of dimensions
4.1 General
For compact rubber products, the dimensions shall be measured 16 hours after vulcanization. In case of dispute, this minimum time may be extended to 72 hours. The measurements shall be completed within three months after the date of shipment to the buyer or before the product is put into use, whichever is shorter. The measurement shall be carried out at standard temperature after environmental conditioning (see GB/T2941). Care shall be taken to ensure that the product is not subjected to harmful storage conditions (see ISO2230) and that the product does not deform during the measurement. 4.2 Test instruments
4.2.1 Measurements shall be made using one or more of the following instruments as appropriate. 4.2.1.1 Solid products may be measured using a dial micrometer gauge, the foot of which shall apply a pressure of 22 kPa ± 5 kPa to rubber with a hardness equal to or greater than 35 IRHD, and a pressure of 10 kPa ± 2 kPa to rubber with a hardness less than 35 IRHD (see GB/T5723 and GB/T 6031).
4.2.1.2 Suitable optical measuring instruments
4.2.1.3 Fixed gauges with upper and lower limits appropriate to the dimensions to be measured. 4.2.1.4 Other measuring instruments, including tape measures (with or without vernier), vernier calipers and micrometers. 4.2.2 The measuring errors of all instruments shall be within the specified tolerance range. 4.2.3 The same measuring instrument shall be used for all measurements intended for comparison. 5 Flatness tolerance
The toleranced surface contains the area between two parallel planes with a distance of tolerance value t (see Figure 1 and 14.2 of ISO1101:1983). The required flatness tolerances are listed in Table 1.
Nominal size d
Less than or equal to
Example of flatness tolerance marking
Required flatness tolerance
mm (unless otherwise specified)
Flatness tolerance t
6Parallelism tolerance
Nominal size #d
Less than or equal to
GB/T3672.2--2002
Table 1 (complete)
m (unless otherwise specified)
Flatness tolerance:
6.1 Sandwich structure (rubber sandwiched between two metal plates) The tolerance surface is included in the area between two parallel planes at a distance of tolerance value t and parallel to the reference plane D (see Figure 2 and 14.7.4 in ISO1101:1983).
The parallelism tolerance required for the product of the waist structure is listed in Table 2. D
- Example of parallelism tolerance marking: Sandwich structure Figure 2
Table 2 Required parallelism tolerance: Sandwich structure Nominal size!
Less than or equal to
mm (unless otherwise specified)
Parallelism tolerance
Cut products of extruded profiles (such as lathe-cut ring products) 6.2
The tolerance surface is contained between two parallel planes parallel to the reference plane E at a distance of tolerance value t (see Figure 3 and 14.7.4 of ISO1101:1983).
The required parallelism tolerances for cut products of extruded profiles are listed in Table 3. ae
Figure 3 Example of parallelism tolerance marking: Cut products of extruded profiles 25
Verticality tolerance
GB/T3672.2--2002
Table 3 Parallelism tolerance required for cut products of extruded profiles M-grade
Parallelism tolerance!
The tolerance surface of the product is contained between two parallel planes with a distance of tolerance value t. and perpendicular to the axis A (reference line) (see Figure 4 and 14.8. in ISO 1101:1983).3). The required verticality tolerance is listed in Table 4.
Example of marking verticality tolerance
Required verticality tolerance
Nominal size d
8Coaxiality tolerancewwW.bzxz.Net
Less than or equal to
mm (unless otherwise specified)
Vertical tolerance 1
8.1 Molded products
The axis of each cylinder connected to the tolerance frame is included in the inner cylindrical surface of the cylindrical band with a diameter of tolerance value tc or tF and coaxial with the reference axis D (see Figure 5 and 1S0) 1101: 1983 14.11.2), but the tolerances between the following sizes are specified differently: 26
GB/T 3672. 2—2002
Figure 5 Example of coaxiality tolerance notation for molded products Tolerances for fixed dimensions (F), which are dimensions within the same mold part that are not affected by deformations such as the thickness of the rubber edge or lateral displacement of different parts of the mold (upper and lower mold plates or mold core) (see Figure 5, diameters α and b). Tolerances for closed mold dimensions (C), which are affected by changes in the thickness of the rubber edge or lateral displacement of different parts of the mold (see Figure 5, diameter c). The coaxiality tolerances required for molded products are listed in Table 5. Table 5 Coaxiality tolerances required for moulded products
Nominal size"
less than or equal to
1) Coaxiality tolerance is determined by the minimum dimension (see dimension 6 in Figure 5) t
Coaxiality tolerance
8.2 Mandrel-supported extrusion products
The centre of the circle connected to the tolerance frame is included in the circle with a diameter of tolerance value t and concentric with the centre of the reference circle A (see Figure 6 and ISO) 1101:1983 rt 14.11,1). The coaxiality tolerances required for mandrel-supported extrusion products are listed in Table 6. 27
GB/T 3672. 22002
1) is applicable only to each section.
Figure 6 Example of coaxiality tolerances for mandrel-supported extrusions Table 6 Coaxiality tolerances required for mandrel-supported extrusions Nominal size d
Less than or equal to
Coaxiality tolerance Φ
8.3 Rotating parts
The tolerances of rotating parts are not marked with coaxiality tolerances, but with the circular run-out tolerances specified in 14.13 of ISO 1101:1983. The tolerance values ​​shall be agreed upon between the parties concerned. 9 Position tolerances
For the position of the metal frame in a rubber product in relation to a recognized position (e.g. the centre of a bushing), a position tolerance may be specified (see 14.10 of ISO 1101:1983).
Due to the variety of applications, the position tolerances shall be agreed upon by the parties concerned. 28
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