1 Scope
This document specifies the machine tool screw support with metric series of thrust angular contact ball bearings, two-way thrust angular contact ball bearings (hereinafter referred to as "bearings") and flanged bearing housing cartridge type unit (hereinafter referred to as "unit") of the code method, external dimensions and technical The conditions.
This document applies to the design, inspection and acceptance of machine tool screws with thrust angular contact ball bearings and units.
2 normative reference documents
The content of the following documents through the normative references in the text and constitute the essential provisions of this document. Among them, note the date of the cited documents, only the date of the corresponding version applicable to this document; do not note the date of the cited documents, its latest version (including all the revision of the list) applicable to this document.
GB/T 272-2017 Method of designating rolling bearings
GB/T 307.1-2017 Rolling bearings, radial bearings, product geometrical specifications (GPS) and tolerance values
3 Terms and definitions
The terms and definitions defined in GB/T 6930-2002 apply to this document.
4 Symbols
The symbols given in GB/T 4199-2003 and GB/T 7811-2015 as well as the following apply to this document.
5 Structural patterns
Common structural types of bearings and units are shown in Figure l to Figure 4.
See Figure A.1 in Appendix A for additional structural types of flanged cartridge units.
6 Code method
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.
7 Marking examples
GB/T 24604-2021 in line with the provisions of the code as shown in 6.5 examples 1 to examples 4 of the bearing or unit are marked as: rolling bearing 7602025 TN/P4QFCA GB/T 24604-2021
Rolling bearing BSB 025062 TN/P4QFCA GB/T 24604-2021
Rolling bearing ZKLN 030062-2RSTN/P4 GB/T 24604-2021
Rolling bearing FU 025080 TN/P4QFCA GB/T 24604-2021
8 External dimensions
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 Technical requirements
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 α 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 Testing method
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.
11 Inspection rules
The inspection rules for bearings are in accordance with GB/T 24608-2009, using the general inspection level Ⅱ, and the inspection items are shown in Table 17. the AQL value of the main inspection items is 1.5, and the AQL value of the secondary inspection items is 4.
12 Marking
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 Packaging
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
1 Scope
2 normative reference documents
3 Terms and definitions
4 Symbols
5 Structural patterns
6 Code method
7 Marking examples
8 External dimensions
9 Technical requirements
10 Testing method
11 Inspection rules
12 Marking
13 Packaging
Appendix A (informative) Unit type FUB
Appendix B (normative) Diagram for measuring the starting frictional torque of a bearing
