Cylindrical Roller Bearing Cage Grooves for Lubrication and Skew Control
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Solution Overview
Problem
Cylindrical roller bearings in machine tool spindles face issues with lubrication properties during oil-air and grease lubrication, leading to temperature rises and skew motions due to inadequate lubricant discharge and radial clearance, which can result in wear and damage.
Innovation Solution
A cylindrical roller bearing design featuring a cage with recessed grooves on the circular ring portions that face the roller end surfaces, allowing for efficient lubricant discharge and preventing skew motions by maintaining a specific relationship between the groove width, roller diameter, and flange height, ensuring effective lubrication and reduced running-in time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a recessed portion is formed in the cage to store lubricant, then lubrication property is improved, but discharge property of lubricant becomes insufficient causing temperature rise
Solution Approach 1:
The cage is divided into multiple functional regions: a first recessed portion for storing lubricant, a second recessed portion for discharging lubricant, and a third recessed portion for guiding rollers. This segmentation allows simultaneous optimization of lubricant storage, discharge, and distribution functions, resolving the contradiction between retaining enough lubricant and enabling its effective discharge.
Solution Approach 2:
The second recessed portion acts as an intermediary discharge channel between the first recessed portion (storage) and the bearing raceway. This intermediate structure enables controlled lubricant flow from storage to discharge, preventing both lubricant starvation and excessive retention that causes temperature rise.
2Ease of operation
If positive radial clearance is used for better sliding performance, then sliding performance is improved, but skew motion occurs due to unrestrained roller movement
Solution Approach 1:
The cage structure provides localized restraint at specific positions through the third recessed portion and roller guiding features, while maintaining positive radial clearance for sliding performance. This localized quality approach allows freedom of movement where needed for sliding while providing restraint where needed to prevent skew motion.
Solution Approach 2:
The cage structure is designed with preliminary anti-action features that prevent skew motion before it can cause damage. The third recessed portion and roller guiding structure proactively restrain roller position, counteracting the tendency toward skew motion that arises from positive radial clearance and unrestricted roller movement.
3Reliability
If excess grease is stored in the cage for grease lubrication, then lubrication is improved, but running-in time increases and temperature rises during initial operation
Solution Approach 1:
The cage is segmented into storage and discharge regions, allowing grease to be stored in the first recessed portion while enabling its rapid discharge through the second recessed portion during running-in. This segmentation resolves the contradiction between having enough grease for lubrication and needing to discharge excess grease quickly during initial operation.
Solution Approach 2:
The discharge of grease occurs in a periodic manner during running-in operation, with grease being discharged through the second recessed portion and then replenished in the first recessed portion. This periodic action allows the system to complete running-in efficiently while maintaining adequate grease supply for ongoing lubrication.
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 design provides satisfactory lubrication properties, prevents skew motions, and reduces temperature rises by ensuring efficient lubricant discharge and maintaining proper radial clearance, thus enhancing the operational reliability of the bearing.
Implementation Method 1
a single recessed groove is formed in an inner wall surface of each of the pair of circular ring portions forming the pocket portion, the recessed groove facing at least a center point of a roller end surface of the cylindrical roller
Implementation Method 2
since an action of a centrifugal force during low-speed rotation or the like is small, there is a problem that oil tends to stay inside the bearing
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
In a cylindrical roller bearing (10), a single recessed groove (25) is formed in an inner wall surface of each of a pair of circular ring portions (22) forming a pocket portion (21), the recessed groove (25) at least facing a center point O of a roller end surface (13a) of a cylindrical roller (13) and open from an inner circumferential surface to an outer circumferential surface of the circular ring portion (22). The recessed groove (25) is spaced apart in a circumferential direction from a pocket corner portion (26) between the circular ring portion (22) and a column portion (23). Thereby, satisfactory lubrication property can be obtained in oil-air lubrication or grease lubrication, and skew of the cylindrical roller can be prevented.