Crossed Roller Bearing Sequencing for Low Runout Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Machine tools and precision applications require bearings with precise runout characteristics, which is challenging due to manufacturing variances in roller dimensions, leading to increased costs from tight size tolerances.
Innovation Solution
The solution involves sequencing rollers in crossed roller bearings by positioning an odd number of high-points with the largest diameters and an equal number of low-points with the smallest diameters around the bearing's circumference, with rollers between them decreasing in size, to minimize assembly error motion and runout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tight size tolerances are applied to all bearing components, then runout precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by differentiating roller positioning based on their radial position. Rollers at the major radius (outer circumference) are positioned with higher precision than rollers at the minor radius (inner circumference). This selective precision approach reduces overall manufacturing cost while maintaining adequate runout precision, as the majority of rollers do not require the same tight tolerances.
Solution Approach 2:
The patent employs asymmetry in the roller sequencing pattern, creating an asymmetric distribution of precision levels around the bearing circumference. The positioning precision varies sinusoidally with angular position, providing higher precision at specific angular locations (major radius) and lower precision at other locations (minor radius), thereby reducing overall manufacturing requirements.
2Ease of manufacture
If roller size variation is allowed, then manufacturing cost decreases, but assembly runout increases
Solution Approach 1:
The patent changes the parameter of roller positioning precision as a function of angular position and radial distance. By varying the positioning tolerance parameter based on location, the patent allows greater roller size variation in regions where it has minimal impact on runout (minor radius), while maintaining tighter control where it matters most (major radius).
Solution Approach 2:
The patent implements local quality by applying different positioning precision requirements to different spatial locations within the bearing. Rollers at the major radius receive enhanced positioning control to compensate for their greater leverage effect on runout, while rollers at the minor radius can tolerate greater size variation, thus reducing overall manufacturing cost.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A bearing includes a plurality of rolling elements (26) spaced around a three-hundred and sixty degree circumferential extent of the bearing. An odd, non-singular number of high-points are positioned as near to evenly as possible about the circumferential extent of the bearing, the high-points defined by locations at which rolling elements with the largest diameters are positioned. An odd, non-singular number of low-points are positioned as near to evenly as possible about the circumferential extent of the bearing, the low-points defined by locations at which rolling elements having the smallest diameters are positioned. The odd, non-singular number of high-points is the same as the odd, non-singular number of low-points, and each low-point is positioned as near to evenly as possible between two adjacent high- points.