Bearings for Industrial Gearboxes - NSK Europe - #29

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Industrial gearboxes 29 Procedures for perfect fit selection To calculate the proper fit for the bearing, it is important to consider the bearing load. At the load application point the inner ring of the bearing undergoes radial compression while opposite to this point the ring expands. This effectively reduces the component interference. The method shown in Equation method 1 may be employed for calculating fit reduction. In practice, the actual interference level selected should always exceed the result from Equation 1. Calculation on the basis of Equation 1 is sufficient for comparatively low loads, expected in most areas of application. If higher loads are expected, however, Equation method 2 should serve as basis for calculation. Load Conditions Examples Tolerances for Housing Bores Axial Displacement of Outer Ring Remarks Solid or Split Housings Rotating Inner Ring Load High Temperature Rise of Inner Ring Through Shaft Paper Dryers G7 Easily Possible – Solid Housing Accurate Running Desirable under Normal or Light Loads Grinding Spindle Rear Ball Bearings JS6 (J6) Possible – High Speed Centrifugal Compressor Free Bearings Direction of Load Indeterminate Grinding Spindle Front Ball Bearings K6 Impossible For heavy loads, interference fit tighter than K is used. When high accuracy is required, very strict tolerances sould be used for fitting High Speed Centrifugal Compressor Fixed Bearings Rotating Outer Ring Load Accurate Running and High Rigidity Desirable under Variable Loads Cylindrical Roller Bearings for Machine Tool Main Spindle M6 or N6 Impossible Minimum noise is required Electrical Home Appliances H6 Easily Possible – Equation Method 1 ÄdF Required Interference fit d Bore diameter (mm) B Width of inner ring (mm) F Radial load (N) Equation Method 2 ÄdF Required Interference fit B Width of inner ring (mm) F Radial load (N) d F1 B B ÄdF = ÄdF 0.08 0.02 F • 10-3 (N) • 10-3 (N)