Spindle Bearing Cage Protrusions for Stable Lubricant Discharge
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Solution Overview
Problem
Existing rolling bearings in machine tool spindle devices face issues with lubricant discharge properties, particularly in low speed rotation ranges, leading to abnormal vibrations and instability due to insufficient lubricant supply or excessive lubricant discharge causing heat generation and wedge effects.
Innovation Solution
A rolling bearing design featuring a cage with convex protruding portions on the annular portions of the outer peripheral surface, guided by the outer ring, which enhances lubricant discharge by creating alternating large gaps and promoting air convection, ensuring smooth lubricant discharge across all rotation ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a typical outer ring guide type cage with minute guide gap is used, then the cage structure is simple, but the lubricant discharge is blocked and remains in the rolling portion causing abnormality
Solution Approach 1:
The annular portions of the cage are segmented with multiple convex protruding portions that create multiple discharge paths. This segmentation allows lubricant to be discharged through multiple gaps between the convex protruding portions and the outer ring, preventing lubricant accumulation while maintaining structural simplicity.
Solution Approach 2:
The convex protruding portions extend in the axial direction, creating discharge paths in the axial dimension. This dimensional approach allows lubricant to be discharged axially through the gaps created by the convex protruding portions, effectively solving the discharge blockage problem without complicating the radial cage structure.
2Reliability
If lubricant is supplied in high speed rotation range, then stable rotation can be achieved, but heat generation due to stirring lubricant may occur
Solution Approach 1:
The convex protruding portions extract excess lubricant from the rolling portion through the created gaps. By removing the harmful excess lubricant that causes heat generation through stirring, the invention maintains the necessary lubrication for stable rotation while preventing overheating in high speed ranges.
3Reliability
If lubricant is supplied in low speed rotation range, then lubrication can be maintained, but wedge effect generates oil film reaction force causing abnormal vibrations
Solution Approach 1:
The convex protruding portions extract and discharge the excessive lubricant that forms the wedge effect in low speed rotation. By removing the lubricant that would otherwise generate harmful oil film reaction forces and vibrations, the invention maintains adequate lubrication while eliminating the source of abnormal vibrations.
4Reliability
If convex protruding portions are formed on annular portions, then lubricant discharge property is improved, but cage structure becomes more complex
Solution Approach 1:
Instead of changing the entire cage structure, the invention applies convex protruding portions only at specific locations on the annular portions where lubricant discharge is needed. This localized modification improves discharge property without significantly increasing overall cage complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The improved lubricant discharge property stabilizes and quietens the operation of the machine tool spindle device across various rotation speeds, preventing abnormal vibrations and ensuring stable performance.
Implementation Method 1
the centrifugal force, the rotation and revolution energy of the rolling elements 104, and the like during high speed rotation are easily used for discharging the lubricant
Implementation Method 2
the discharge property of the lubricant may be insufficient in a low speed rotation range
Data Source
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AI summary
This rolling bearing comprises: an inner ring having an inner raceway formed in an outer circumferential surface thereof; an outer ring having an outer raceway formed in an inner circumferential surface thereof; a plurality of rolling elements that are provided between the inner raceway and the outer raceway so as to be freely rollable; and a retainer having a plurality of pockets in which the rolling elements are retained. The retainer has a pair of annular parts that are disposed side by side in the axial direction, and a plurality of columnar parts that are disposed spaced away from each other in the circumferential direction so as to connect between the pair of annular parts. At least one of the pair of annular parts has a plurality of bulgingly protruding portions that are formed on the outer circumferential surface in the circumferential direction so as to be spaced away from each other and that are guided by the inner circumferential surface of the outer ring. The bulgingly protruding portions are disposed adjacent to the respective pockets in the axial direction.