GB/T 24604-2021Rolling bearings-Angular contact thrust ball bearings and units for machine tool screws (English PDF)

6.1 Code composition

Bearings and units code by type code, size code and post code composition, the order of arrangement, see Table 1.

6.2 Type codes

Bearings and units are divided into six types, type code with capital Latin letters or numbers, the code and its meaning in Table 2.

6.3 Size codes

See Table 3 for the composition of the bearing and unit size codes and the method of representation.

8.1

External dimensions of type 76 02 series, 03 series bearings are in accordance with the provisions of Table 4 and Table 5.

8.2

External dimensions of BSB type bearings in accordance with the provisions of Table 6.

8.3

The dimensions of ZKLN bearings are in accordance with Table 7.

8.4

The external dimensions of the ZKLF type bearings are in accordance with Table 8.

8.5

The external dimensions of FU-type units are in accordance with Table 9 and the external dimensions of FUB-type units are shown in Table A.1.

9.1 Material and heat treatment

9.1.1 Bearing inner and outer rings and rolling bodies are generally made of high quality GCr15 bearing steel not less than that specified in GB/T 18254-2016, and their heat treatment quality should be in accordance with the provisions of GB/T 34891-2017. When the user has special requirements, other materials with comparable or better performance can also be used. The flange barrel is made of 55, 65Mn, 70Mn high quality carbon structural steel or other materials meeting the performance requirements in accordance with GB/T 699-2015, and the hardness after heat treatment is 55HRC~62HRC.

9.1.2

The cage is generally made of engineering plastic PA66-GF25 and the material and technical requirements of the finished product shall conform to the provisions of JB/T 7048-2011. Other materials with comparable or better performance can also be used.

9.1.3

seal rubber is generally used in accordance with JB/T 6639-2015 nitrile rubber, polyacrylate rubber, hydrogenated nitrile rubber or fluorine rubber manufacturing, can also be used equivalent or better performance of other materials manufacturing; seal skeleton and dust cover is generally used in line with the provisions of GB/T 5213-2019 low carbon steel plate manufacturing, can also be used equivalent or better performance of other materials manufacturing. Other materials with comparable or better performance can also be used.

9.2 Tolerances

The limit deviation of the width of a single collar is -8.as mm. after the bearing assembly, the tolerance of the bearing should be in accordance with the provisions of GB/T 307,1-2017 in addition to level 4, level 2, but also in accordance with the provisions of Table 10. For the tolerances of FU-type units, they should also comply with the provisions of table 1l.

The meaning of the symbols U and L in the table:

U - the upper limit deviation;

V - L - lower limit deviation.

9.3 Surface roughness

The surface roughness of the mating surfaces and end faces of the bearings shall not be lower than the requirements for class 4 and class 2 bearings in table 1 of GB/T 307.3-2017.

9.4 Contact angle

Nominal contact angle alpha for 60 °, contact angle tolerance for Shi 3 °, the same group of bearings should not exceed 2 ° contact angle difference, two-way thrust angular contact ball bearing contact angle difference between the two columns of steel balls should not exceed 3 °.

9.5 Protrusion amount

Under preload, the projection of the outer ring end face of a single set of bearings should be "0", and the tolerance of the projection should be in accordance with table 12. If the bearings are supplied in a single set, the user can arrange and install them according to his needs.

10.1 Tolerances

10.1.1

The measurement method of dimensional tolerance and rotational accuracy of the bearing shall be in accordance with the provisions of GB/T 307.2-2005.

10.2 Surface roughness

The measurement method of the surface roughness of the mating surface and end face of the bearing is in accordance with the provisions of JB/T 7051-2006.

10.3 Contact angle

Bearing contact angles are measured using special instruments.

10.4 Pre-load, projection

The measurement method of bearing preload and projection is determined in consultation with the user.

10.5 Starting friction torque

The starting frictional torque of a single set of bearings in type 76, BSB bearings and bearing units is measured by putting two sets of bearings together in the form of a back-to-back (DB) set, with 0.5 times the measured value as the starting frictional torque of a single set of bearings; for ZKLN and ZKLF bearings, the starting frictional torque is measured with a single set of bearings. The measurement method is in accordance with GB/T 32562-2016 and the provisions of Appendix B of this document.

10.6 Residual magnetism

The measurement method of bearing residual magnetism is in accordance with the provisions of JB/T6641-2017.

12.1

bearing inner and outer ring S., S. The maximum point should be marked in the bearing inner and outer ring end surface, the symbol by the manufacturer to determine.

12.2

Bearing grouping structure type, grouping after the bearing sign should be in line with the provisions of GB / T 32334-2015.

12.3

unit should be marked on the outer diameter of the sleeve corner line, end face mark bearing code, trademark or manufacturer code.

12.4

Other marking requirements of the bearing in accordance with the provisions of GB/T24605-2009.

13.1

Assembled bearings should be packaged in groups in accordance with GB/T 8597-2013. The individual bearings in the assembly should be packed in clean plastic bags with individual seals, then placed in the same box and separated by rust-proof cardboard.

13.2

For universal assembly bearings and bi-directional thrust angular contact ball bearings, the individual bearings shall be packed in clean plastic bags and placed in the packing box.

13.3

After assembly of the units, they are packed in a clean plastic bag and placed in a box.

Appendix A (informative) Unit type FUB Appendix B (normative) Diagram for measuring the starting frictional torque of a bearing […]