Double-Row Bearing Misalignment Control via Positioning Pins
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Solution Overview
Problem
The existing ultrathin double-row rolling bearings used in medical equipment like CT scanners face challenges in achieving low noise, low vibration, and high rigidity due to misalignment issues and high manufacturing costs, particularly when processing the fitting structure between raceway rings with large diameters.
Innovation Solution
A double-row rolling bearing design that incorporates positioning members, such as reamer bolts or positioning pins, to suppress misalignment between raceway rings, allowing for easier manufacturing and reduced costs while maintaining low noise and high rigidity, achieved by setting the pitch angle between positioning holes to an angle other than a multiple of the pitch angle between rolling elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fitting structure with projection and recess is used to prevent misalignment between raceway rings, then misalignment is suppressed, but manufacturing cost significantly increases due to the need for high-precision processing
Solution Approach 1:
The patent replaces the expensive high-precision fitting structure with a cost-effective positioning member (such as a positioning pin or spacer) that achieves the same alignment function at lower manufacturing cost. The positioning member is a simple, inexpensive component that can be easily manufactured and installed.
Solution Approach 2:
The patent introduces a positioning member as an intermediary element between the raceway rings to achieve accurate alignment. This positioning member serves as a mediator that establishes the correct relative position without requiring direct high-precision fitting between the raceway rings themselves.
2Manufacturing precision
If high-precision processing of projection and recess is performed to reduce fitting clearance, then misalignment is suppressed, but manufacturing time and cost increase
Solution Approach 1:
The patent employs positioning members that are pre-manufactured with precise dimensions and then assembled into the bearing structure. This preliminary preparation of alignment components separates the precision requirement from the main raceway ring manufacturing, allowing mass production of standard components and reducing overall manufacturing time.
Solution Approach 2:
The positioning members are simple, inexpensive components that can be quickly manufactured and replaced if needed, eliminating the need for time-consuming high-precision processing of the main raceway rings.
3Ease of manufacture
If the pitch angle between positioning holes is set to a multiple of the pitch angle between rolling elements, then manufacturing is simplified, but misalignment suppression effectiveness is reduced
Solution Approach 1:
The patent specifies particular pitch angle relationships between positioning holes to optimize both manufacturing ease and alignment performance. By carefully selecting the pitch angle (such as making it equal to or a specific fraction of the rolling element pitch angle), the patent achieves effective misalignment suppression while maintaining manufacturability.
Solution Approach 2:
The patent employs asymmetric positioning hole arrangements where the pitch angle between positioning holes is deliberately set to a specific relationship with the rolling element pitch angle, creating an optimized geometric configuration that balances manufacturing simplicity with alignment effectiveness.
Data Source
AI summary
A double-row rolling bearing includes an outer member having two raceway surfaces on an inner circumference thereof, an inner member having two raceway surfaces on an outer circumference thereof, the inner member being arranged on an inner side of the outer member, two rows of rolling elements assembled into a space between each of the two raceway surfaces of the outer member and each of the two raceway surfaces of the inner member, and a retainer for retaining the rolling elements. Any one of the outer member and the inner member includes a pair of raceway rings, both of the pair of raceway rings being fastened with a fixing bolt and having positioning holes into which a positioning member is fit-inserted, to thereby suppress misalignment in a radial direction of the pair of raceway rings.