GB/T 25770-2024 PDF English
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Rolling bearings - Bearings for railway wagon
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GB/T 25770-2024: Rolling bearings - Bearings for railway wagon---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT25770-2024
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 21.100.20
CCS J 11
Replacing GB/T 25770-2010
Rolling bearings -- Bearings for railway wagon
Issued on: SEPTEMBER 29, 2024
Implemented on: APRIL 01, 2025
Issued by. State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword... 3
1 Scope... 5
2 Normative references... 5
3 Terms and definitions... 6
4 Symbols... 7
5 Coding method... 7
6 Structural types... 8
7 Overall dimensions... 8
8 Technical requirements... 8
9 Test methods... 14
10 Inspection rules... 17
11 Marks... 18
12 Anti-rust packaging... 19
13 Storage... 19
Annex A (normative) Cleanliness testing and assessment methods... 20
Annex B (normative) Ultrasonic testing of bearing outer rings... 23
Rolling bearings -- Bearings for railway wagon
1 Scope
This document specifies the coding method, structural type, overall dimensions,
technical requirements, test methods, inspection rules, marks, rust-proof packaging and
storage of rolling bearings for railway wagon.
This document applies to the manufacture of rolling bearings for railway wagon used
at speeds not exceeding 160 km/h.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
GB/T 272, Rolling bearings -- Identification code
GB/T 307.2-2005, Rolling bearings -- Measuring and gauging principles and
methods
GB/T 699-2015, Quality carbon structure steels
GB 1922-2006, Petroleum solvents for paints and cleaning
GB/T 2828.1-2012, Sampling procedures for inspection by attributes -- Part 1.
Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot
inspection
GB/T 2829-2002, Sampling procedures and tables for periodic inspection by
attributes (apply to inspection of process stability)
GB/T 3203-2016, Carburizing steels for bearing
GB/T 4199, Rolling bearings -- Tolerances -- Definitions
GB/T 5213-2019, Cold rolled low carbon steel sheet and strip
GB/T 6930, Rolling bearings -- Vocabulary
GB/T 7811, Rolling bearings -- Symbols for physical quantities
GB/T 8597-2013, Rolling bearings -- Rust proof packaging
A steel plate stamping sealing part fixed on the outer ring of the bearing, combined with
the oil seal and the seal seat to form a space for storing grease.
NOTE. It is used to prevent grease leakage or foreign matter intrusion, suitable for 352226X2-2RZ
bearings.
3.2 seal wear ring
Located on the outside of the end face of the inner ring of the bearing, it is a ring-shaped
part fixed on the axle and combined with the oil seal and sealing cover to form a space
for storing grease.
NOTE. It is used to prevent grease leakage or foreign objects from entering.
3.3 oil seal
An annular sealing part composed of a metal frame and rubber.
NOTE. It is used to prevent grease leakage or foreign objects from entering.
3.4 seal assembly
An assembly consisting of a sealing cover, an oil seal and a sealing seat.
NOTE. It is used to prevent grease leakage or foreign matter intrusion, suitable for 352226X2-2RZ
bearings.
4 Symbols
The symbols given in GB/T 7811 apply to this document.
5 Coding method
5.1 The coding method for rolling bearings for railway wagon (hereinafter referred to
as "bearings") shall comply with the provisions of GB/T 272.The bearing post-code
may also be abbreviated, using one English letter to represent the meaning of multiple
post-codes, such as "A" and "B" to represent changes in structural type.
5.2 Non-standard bearing codes are determined by the manufacturer.
Example. X197726 bearing.
Where. X - manufacturer code; 19 - structure code; 7 - type code; 7 - diameter series
code; 26 - inner diameter code, d = 130 mm.
8.11 Appearance quality
8.11.1 The working and matching surfaces of rollers and rings before phosphating shall
not have burns, soft spots or decarburization. They shall also not have defects such as
burrs, scratches, stains, dents, rust, bumps, etc.
8.11.2 The connection between the bearing inner ring and seal seat assembly chamfer
and the inner cylindrical surface shall be smooth and without sharp edges.
8.11.3 The appearance quality of the cage shall comply with the requirements of TB/T
3567-2021.
8.11.4 The appearance quality of the oil seal shall comply with the requirements of
TB/T 3419-2015.
8.12 Others
8.12.1 The seal cover, seal seat, oil seal and seal assembly of the bearing shall be pressed
with a special mold. After pressing, the bearing shall be intact and undamaged and meet
the requirements of the product drawing.
8.12.2 If the user has other technical requirements for bearings, they can negotiate with
the manufacturer to determine them.
9 Test methods
9.1 Inspection of materials and heat treatment
The chemical composition, non-metallic inclusions, mechanical properties and other
requirements of the carburized bearing steel used to manufacture the rings shall be
inspected in accordance with the provisions of GB/T 3203-2016.The quality
requirements after heat treatment shall be inspected in accordance with the provisions
of JB/T 8881-2020.
The chemical composition, non-metallic inclusions and other requirements of high
carbon chromium bearing steel used to manufacture rollers shall be inspected in
accordance with the provisions of GB/T 18254-2016.The quality requirements after
heat treatment shall be inspected in accordance with the provisions of GB/T 34891-
2017.
9.2 Tolerance measurement
The measurement of bearing size tolerance and rotation accuracy shall comply with the
provisions of GB/T 307.2-2005.
9.3 Measurement of axial clearance
10.2 Type inspection
10.2.1 Bearings shall be subject to type inspection in any of the following situations.
a) When a new product is finalized;
b) When there are major changes in design, materials, processes, etc. that may affect
product quality and performance;
c) When a product is discontinued for more than one year and production is resumed.
10.2.2 Type inspection items and sampling numbers shall be in accordance with the
provisions of Table 12.
10.2.3 The products for type inspection shall be selected from the same batch of
products that have passed the factory inspection. The exit-factory inspection items shall
be re-inspected first, and the bench test shall be carried out after the re-inspection is
passed. In the bench test assessment, each batch of tests shall be carried out in
accordance with the provisions of GB/T 2829-2002.A sampling plan shall be selected.
The sample size shall be in accordance with the provisions of Table 12.The qualified
judgment number is 0.The unqualified judgment number is 1.
11 Marks
11.1 Mark the following at intervals on the circumference of the groove on the outer
surface of the bearing outer ring. bearing model, trademark (or manufacturer code),
year and month of production (the first two digits are the year, the last two digits are
the month), and production sequence number (arranged in six Arabic numerals). The
manufacturer may also add internal information or necessary external information.
Example. The marks on the groove on the outer surface of the outer ring are shown in
Figure 4.
11.2 Marks shall be evenly distributed on the back of the inner ring. bearing model,
trademark (or manufacturer code), production year and month (the first two digits are
the year, the last two digits are the month), material batch number (arranged in three-
digit Arabic numerals).
Example. The marks on the back of the inner ring are shown in Figure 5.
11.3 To increase the traceability of bearings, it is advisable to use the DMC two-
dimensional code mark. The marking requirements are determined by the user and the
manufacturer.
11.4 Other requirements for marking shall comply with the provisions of GB/T 24605-
2009.
8 Cleaning fluid (No. 5 solvent oil in accordance with GB 1922-2006) Several
9 Anhydrous ethanol Several
10 Other common tools 1 set
A.2.2 Preparation for testing
A.2.2.1 The cleanliness test shall be conducted in a clean, well-ventilated test room with
safety facilities. The dust falls per unit area W0 in the test room for 24 consecutive hours
shall not exceed 80 mg/m2.
A.2.2.2 Operators shall wear clean work clothes, work shoes and hats, and wash their
hands.
A.2.2.3 All cleaning tools and containers shall be cleaned.
A.2.2.4 The cleaning solution used shall be filtered through a membrane.
A.2.2.5 Place the filter flat in the cleaning solution and soak for 10 min. After taking it
out, wait for the cleaning solution to evaporate and then place it in a 100℃ ± 5℃ oven
to dry for 60 min. After taking it out, place it in a dryer to cool for 30 min. Then weigh
it (m1) for use (weigh twice with an analytical balance. The difference shall not be
greater than 0.4 mg).
A.2.3 Measurement of dust falls in the test room
A.2.3.1 Determine the test points based on the area of the test room. When the area is
less than 100 m2, select one test point. When the area is between 100 m2~300 m2, select
two test points at the same time. When the area is greater than 300 m2, select three test
points at the same time. The distance between two test points shall not be less than 5 m.
A.2.3.2 Clean the dust receiving plate with cleaning fluid and then clean it with
anhydrous ethanol.
A.2.3.3 Place the dust collecting plate on the operating table at the testing point in the
testing room and record the start time.
A.2.3.4 After 24 h, place the sampled dust receiving plate into a cleaning liquid
container. Scrub it three times with a brush. Rinse it twice with new cleaning liquid.
Collect the cleaning liquid.
A.2.3.5 Filter the cleaning liquid through a filter.
A.2.3.6 Place the filter screen containing impurities in a drying oven at 100℃±5℃ and
dry for 60 min. After taking it out, place it in a dryer and cool it for 30 min. Then weigh
the mass of the filter screen m2 (weigh twice with an analytical balance, the difference
shall not be greater than 0.4 mg).
A.2.4 Measurement of bearing cleanliness
Annex B
(normative)
Ultrasonic testing of bearing outer rings
B.1 Testing personnel
Personnel engaged in ultrasonic testing shall obtain an ultrasonic testing qualification
certificate of Level 2 or above as specified in GB/T 9445-2015.
B.2 Equipment and instruments
B.2.1 Ultrasonic detector
B.2.1.1 The operating frequency range of the ultrasonic detector shall be at least 1
MHz~10 MHz. Other performance indicators shall comply with the provisions of JB/T
10061.
B.2.1.2 The real-time sampling frequency of the digital ultrasonic detector hardware
shall be no less than 100 MHz.
B.2.2 Probe
The specification is 5N5×5FG10 dual crystal straight probe or dual crystal straight
probe with similar technical indicators. If a probe with similar technical indicators is
used, the technical indicators shall be verified and it can only be used after passing the
review.
B.2.3 Coupling medium
B.2.3.1 Engine oil, grinding fluid or other suitable coupling medium shall be used.
B.2.3.2 The same coupling medium shall be used when adjusting detection sensitivity,
calibrating instruments and performing ultrasonic testing operations.
B.2.4 Test block for ultrasonic sensitivity of bearing outer ring
B.2.4.1 The material and heat treatment status of the bearing outer ring ultrasonic
sensitivity test block (hereinafter referred to as the test block) are the same as those of
the bearing ring being tested.
B.2.4.2 Before machining, the test block shall be subjected to ultrasonic testing with a
sensitivity of φ0.5 mm flat bottom hole. No defect reflection wave shall appear inside
the test block.
B.2.4.3 The surface roughness of the test block detection surface shall not be greater
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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