Segmented Bearing Cage with Assembly Wire
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Solution Overview
Problem
Existing bearing cages for medium-to-large rolling-element bearings face challenges in achieving a combination of strength, elasticity, and sliding behavior, particularly due to the high thermal expansion coefficient of plastics, which complicates manufacturing and dimensional accuracy, and results in increased costs and limited radial strength.
Innovation Solution
A combined bearing cage design using a combination of bearing cage segments made from metal or plastic, along with metal or synthetic fiber assembly wires, where the segments are threaded onto or through the wires to form pockets for rolling elements, allowing for secure attachment and reduced thermal expansion, enabling easier assembly and improved radial stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plastic solid cages are manufactured using injection-molding methods, then favorable combination of strength and elasticity is achieved, but thermal expansion coefficient is substantially greater than steel leading to clamping effect and dimensional accuracy loss
Solution Approach 1:
The patent uses composite materials by combining plastic bearing cage segments with metal assembly wires. The plastic segments provide strength and elasticity while the metal wires provide dimensional stability and low thermal expansion. This composite structure resolves the contradiction by allowing the plastic to maintain its favorable mechanical properties while the metal components compensate for thermal expansion issues.
Solution Approach 2:
The patent changes the material parameter (thermal expansion coefficient) by introducing metal assembly wires with substantially lower thermal expansion coefficients compared to plastic. This allows the overall structure to maintain dimensional accuracy while retaining the plastic segments' mechanical advantages.
2Weight of moving object
If plastic cages are used for medium-to-large bearing diameters, then weight savings and low friction are achieved, but radial strength is significantly limited
Solution Approach 1:
The patent creates a composite structure where plastic segments provide low weight and friction while metal assembly wires provide the necessary radial strength. This resolves the contradiction by combining materials with complementary properties - the lightweight plastic for weight reduction and the strong metal for radial strength.
Solution Approach 2:
The patent divides the bearing cage into separate plastic segments that are assembled using metal wires. This segmentation allows the plastic portions to contribute weight savings and low friction while the metal connection elements provide the structural strength needed for medium-to-large bearing diameters.
3Weight of moving object
If purely plastic cages are used, then low material density and good emergency running properties are achieved, but clamping effect results when heat is generated
Solution Approach 1:
The patent uses a composite of plastic segments and metal assembly wires. The plastic provides low density and good emergency running properties while the metal wires with low thermal expansion coefficients prevent clamping effects when heat is generated, thus maintaining reliability under thermal conditions.
4Strength
If steel-bolt cage or steel cage separately is used for medium-to-large bearings, then required strength is achieved, but manufacture is very expensive
Solution Approach 1:
The patent segments the bearing cage into plastic components that can be manufactured using cost-effective injection-molding methods, connected by metal assembly wires. This segmentation allows most of the cage structure to be made from inexpensive plastic while using minimal metal only where strength is critical, significantly reducing manufacturing costs compared to fully metal cages.
Solution Approach 2:
The patent replaces expensive metal cage components with cheaper plastic segments for the majority of the cage structure, using metal wires only for essential connection points. This substitution of expensive materials with cheaper alternatives while maintaining necessary strength reduces manufacturing costs.
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 enhances the strength and radial stability of bearing cages, reduces thermal expansion issues, and allows for cost-effective manufacturing, enabling the use of plastic segments in larger diameters while maintaining low friction and wear, and providing excellent emergency running properties and weight savings.
Implementation Method 1
The friction- and tearing- forces act on the bearing cage in the circumferential direction
Implementation Method 2
the thermal expansion coefficient of plastic, which is substantially greater than that of steel, so that in a purely plastic cage, when heat is generated a clamping effect of the rolling elements can result
Data Source
AI summary
A bearing cage for a rolling-element bearing includes a plurality of bearing cage segments configured to receive rolling elements in rolling-element pockets. Also included is at least one assembly wire, and each of the cage segments includes a coupling arrangement configured to thread the bearing cage segment onto the at least one assembly wire such that at least one rolling-element pocket is formed by two of the plurality of bearing cage segments adjacent in the circumferential direction that are threaded on the assembly wire. The bearing cage also includes an assembly device configured to convey an end of the assembly wire from an installation position to an axially far-side coupling arrangement of a bearing cage segment, through the axially far-side coupling arrangement of all bearing cage segments located on a bearing inner ring, and back again towards the installation position.