Clearance Control Of Deep Groove Ball Bearings

In the mass production of deep groove ball bearings, manufacturers usually control radial clearance parameters through axial clearance calibration. However, this conventional method easily causes radial clearance out-of-tolerance after the assembly and sleeving of deep groove ball bearings. To solve this technical problem, strict precision control is implemented for the inner and outer raceways and steel balls of deep groove ball bearings. Meanwhile, a compression calculation method is adopted for axial clearance calibration of deep groove ball bearings. On the basis of the original radial clearance range of deep groove ball bearings, the lower limit value remains unchanged, while the upper limit value is compressed by 15%. The axial clearance data calculated by this optimized method is taken as the core benchmark to accurately control the actual radial clearance of assembled deep groove ball bearings. Practical case verification proves that this optimized clearance control method fully meets the production and process requirements of deep groove ball bearings.

Clearance Analysis of Angular Contact Ball Bearings

For angular contact ball bearings, internal clearance is a core parameter that directly determines the fatigue life and operating stability of bearings. Unreasonable clearance selection will easily lead to abnormal wear and early failure of bearings during service.

Angular contact ball bearings are mostly applied in paired installation modes, mainly including pre-clearance assembly and preload assembly. For machine tool bearings requiring high rigidity performance, preload assembly is commonly adopted. Such bearings feature tiny shaft fit interference (only several microns), so the influence of fit interference on working clearance can be ignored during pairing assembly. In contrast, for bearings with large assembly interference, the impact of interference on radial clearance must be fully considered, and the pre-clearance configuration is prioritized in such working conditions. In accordance with the industry standard JB/T 10186-2000, only the pre-clearance values of 7200B and 7300B bearing series are clearly specified, while no unified standard is provided for other series. Therefore, targeted theoretical calculation is required to select a scientific and reasonable clearance range for non-standard series bearings.

Factors Affecting the Preload of Angular Contact Ball Bearings

Appropriate increase of bearing preload can effectively improve the overall rigidity of bearing operation. Nevertheless, excessive preload will cause abnormal heat generation inside the bearing, accelerating component wear and leading to early service failure. In positioning preload design, the final preload value is comprehensively determined by actual installation conditions, mainly including bearing matching tolerance, high-speed centrifugal effect and operating temperature rise.

1. Bearing Matching Tolerance

For precision machine tool bearings, the inner ring usually adopts interference fit with the shaft, while the outer ring adopts clearance fit with the bearing seat. The interference assembly of the inner ring will change the original radial dimension of the bearing, resulting in the increase of actual preload after installation.

2. Centrifugal Effect

During high-speed operation of bearings, the inner raceway will produce micro deformation and expansion under centrifugal force. This structural change alters the original radial clearance of the bearing and further increases the operating preload.

3. Operating Temperature Rise

In the working state, internal friction of bearings, lubricant stirring resistance and external environmental factors will jointly cause continuous temperature rise, resulting in thermal expansion of bearing components and changing the matching clearance state.

Through comprehensive analysis, three key conclusions are summarized as follows: First, among all bearing structural parameters, contact angle exerts the most significant influence on the variation of bearing axial clearance. Second, in terms of the three major influencing factors (interference fit, centrifugal effect and temperature rise), interference fit contributes the most to bearing clearance changes. Third, in actual engineering application, if bearings adopt interference fit design, the clearance variation caused by interference must be fully considered. Reasonable reserved clearance is essential to avoid excessive preload and premature bearing failure. In the paired installation of angular contact ball bearings, the variation of radial clearance should be converted into axial clearance variation for unified analysis and accurate parameter calibration.

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