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1, INA bearing limit speed
The running speed of the bearing is mainly affected by frictional heating the bearing temperature rise caused by the restrictions, when the speed exceeds a certain threshold, the bearing will burn and not continue to rotate. INA bearings limit speed is not to produce friction heat burns and continuous rotation of the boundary values.
Therefore, INA bearing limit speed depends on the bearing type, size and accuracy and lubrication, the quality and quantity of lubricant, cage and type of material, loading conditions and other factors. All kinds of bearings with grease lubrication and oil lubrication (oil bath lubrication) speed limit when contained in the table bearing size, its value represents a standard design bearing under general loading conditions (C/P>=13, Fa/Fr<=0.25) under rotating speed limits. In addition, the lubricant according to their types and grades of different, may also is superior to other performance but is not suitable for high-speed rotation.
C/P<13 modified load limit speed (i.e. equivalent dynamic load of P beyond the basic dynamic load rating of around 8% of C), or axial load synthesis load bear radial load of more than 25%, the speed limit is modified by the type.
Na=f1*f2*n Na here: the speed limit, the modified RPM F1: correction factor F2 related to loading conditions: correction coefficients associated with synthetic load of N: the speed limit of general loading conditions, RPM (refer to INA table bearing size) C: dynamic load, the basic rating N{kgf} P: equivalent dynamic load, Fr: N{kgf} the radial load, axial load, N{kgf} Fa: the speed limit of N{kgf} sealing ring of ball bearings with contact seals (RS) limit speed ball bearing by the seal ring contact surface line speed limit, allowing the line speed depends on the rubber sealing ring.
2, heat treatment and spreading method
Two quenched bearing steel carbide by quenching martensite, a small amount of undissolved and about 12% ~ 14% of the retained austenite. The quenched martensite and residual austenite belongs to the unstable structure, in the process of tempering the decomposition of martensite makes the volume shrinkage of steel, and the residual austenite decomposition makes the volume swell steel.
Along with the improvement of tempering temperature, the transformation of retained austenite decomposition quantity increases, in ensuring the technical requirements under the condition of increasing the hardness, tempering temperature, the retained austenite transforms into martensite decomposition, large volume, can make the volume increases, relative to outside diameter grinding quantity increases, this method can be used to make the INA bearing ring defects in the normal grinding conditions become obsolete parts to save.
This method for a larger residual austenite content of thick, heavy workpieces (especially for roller bearings) effect is obvious. According to the different specifications, different size, different thickness of the parts in the actual production to tempering process is different, the hardness and deformation under the premise, the organization change fully, greatly expanding, a corresponding increase in grinding, save waste.
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| 7215BDF NSK | 75 | 130 | 25 |
| 7215ADF NSK | 75 | 130 | 25 |