Segmented Resin Bearing Retainer for Thermal Binding Relief
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Solution Overview
Problem
Conventional thrust ball bearing retainers are expensive and prone to distortions in large bearings, and they fail to function effectively at extreme temperatures or without liquid lubricants due to thermal binding and lubricant incompatibility.
Innovation Solution
The retainer is segmented into multiple circular arc pieces with guided features and rounded ends to minimize thermal effects and wear, and incorporates a solid or liquid lubricant mechanism based on environmental conditions, using electroplating and specific materials for optimal friction and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solid single-piece retainer is used for large thrust ball bearings, then the bearing can support heavy loads, but the retainer becomes expensive and prone to distortions such as excessive out-of-round, out-of-flatness, and torsional wrap
Solution Approach 1:
The retainer is divided into multiple segments (typically 2-4 segments) instead of a single-piece construction. Each segment is manufactured separately and then assembled together using connecting elements such as pins or rivets. This segmentation allows each individual segment to be manufactured more easily with better dimensional control, reducing distortions like out-of-round and out-of-flatness, while the combined segmented structure maintains the load-bearing capacity of a solid retainer.
2Device complexity
If a solid single-piece retainer is used, then the structure is simple, but thermal induced binding occurs due to coefficient of thermal expansion mismatch between retainer and raceway materials at extreme temperatures
Solution Approach 1:
The segmented retainer design introduces expansion joints between segments that allow for differential thermal expansion. Each segment can expand or contract independently relative to the others, accommodating the coefficient of thermal expansion mismatch between the retainer material and raceway materials. This prevents thermal induced binding while maintaining structural integrity across extreme temperature ranges.
Solution Approach 2:
The retainer segments are designed with specific geometric parameters including arc-shaped configurations and controlled clearances between segments. These parameter changes allow the retainer to flex and accommodate thermal expansion differences. The segments can rotate slightly relative to each other around the bearing axis, providing thermal compensation without compromising the overall structural simplicity.
3Reliability
If conventional liquid lubricant systems are used, then lubrication is effective at normal temperatures, but the system fails when ambient temperature is below pour point or above flash point of the liquid lubricant
Solution Approach 1:
The retainer incorporates solid lubricant materials (such as PTFE, graphite, or other solid lubricants) applied to the raceway surfaces and/or embedded in the retainer segments. Solid lubricants remain effective across a much broader temperature range compared to liquid lubricants, maintaining lubrication properties below pour points and above flash points. This parameter change from liquid to solid lubrication mechanism extends the operational temperature range while maintaining effective lubrication.
Solution Approach 2:
The retainer segments are manufactured as composite structures combining the base retainer material (such as steel or polymer) with solid lubricant materials. The solid lubricant is applied as coatings, impregnated into the material structure, or integrated as layered composite construction. This composite approach maintains the mechanical strength of the base material while providing the temperature-resistant lubrication properties of solid lubricants.
4Loss of energy
If conventional liquid lubricants are used, then friction is reduced at normal operating conditions, but the system becomes inapplicable where liquid lubricants are not usable due to temperature constraints
Solution Approach 1:
The system transitions from liquid lubricant parameter regime to solid lubricant parameter regime. Solid lubricants operate through different mechanisms (such as shear plane formation, transfer film creation, or layered structure shearing) that are effective across extreme temperature ranges. This parameter change eliminates dependence on liquid lubricant properties that are temperature-sensitive, reducing friction loss while expanding applicability to environments where liquid lubricants cannot function.
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
This design reduces thermal-induced torque and friction, prevents lubricant deposition, and ensures reliable operation across varying temperatures and lubrication conditions, making large thrust ball bearings more cost-effective and adaptable.
Implementation Method 1
thermal induced binding resulting from a coefficient of thermal expansion mismatch between the retainer and raceway materials
Implementation Method 2
electroplating and specific materials for optimal friction and wear resistance
Data Source
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AI summary
A thrust ball bearing retainer a large size of bearings with the bearing raceways being modified using a surface enhancement process such as hard anodizing coating, which provides low friction coefficient and initial wear rate. The retainer material is selected to be molded, synthetic resin, self-lubricated material reinforced with carbon fiber, molybdenum disulfide, and PTPE. This lubrication system eliminates the thermal induced bearing torque effect due to viscosity. The retainer contains multiply segments with an inner race guided configuration, an alternative ball pocket cross section design and a ball pocket slotted configuration to reduce the thermal induced effects due to coefficient of thermal expansion mismatch between the raceway and the retainer material (2) to enhance the producibility of the retainer due to out-of-round, out-of-flatness and torsional wrap, and (3) to reduce the manufacturing cost. The pocket design with an oval cross section instead of a circular cross section also reduces the localized thermal induced effect which would otherwise result in a pinching condition between the ball and the retainer. The alternative slotted retainer pocket design is used to increase the compliance between ball/pocket interfaces, which helps to reduce the dynamic induced effects. The ends of the retainer segments are designed to reduce the interactive transferring, circumferential force between two adjacent segments.