Segmented Plastic Roller Bearing Cage Assembly

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Solution Overview

Problem

Existing roller bearing cages face challenges in achieving dimensional accuracy and cost-effectiveness, particularly in large sizes, due to material limitations and the complexity of injection molding processes, which often result in high scrap rates and increased tooling costs.

Innovation Solution

The use of segmented cage designs, where individual segments are connected during assembly using circumferentially extending connecting elements, allowing for reduced shrinkage and improved accuracy, and enabling the use of smaller, more economical tools, with the option for reversible connections for cost-effectiveness and ease of replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If injection molding process is used to manufacture complete large roller bearing cages, then complex geometries can be reproduced, but dimensional accuracy deteriorates and scrap rate increases

Engineering Contradiction:
Improvecomplex geometry reproductionVSAvoiddimensional accuracy
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The cage is divided into multiple segments that are manufactured separately using injection molding and then assembled together. Each segment is smaller and easier to mold with high precision, while the complete cage achieves complex geometry through the assembly of multiple precision-molded segments.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If injection molding process is used for large roller bearing cages, then complete cage can be produced, but tooling costs and manufacturing complexity increase

Engineering Contradiction:
Improvecomplete cage productionVSAvoidtooling complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The manufacturing process is segmented into producing individual cage segments through injection molding, then assembling them. This reduces tooling size and complexity compared to molding a complete large cage, while still achieving complete cage production through systematic assembly of standardized segments.

Inventive Principle:
Principle #1Segmentation

3Productivity

If injection molding process is used for large roller bearing cages, then production can be scaled, but material loss and cavity formation increase

Engineering Contradiction:
Improveproduction scalabilityVSAvoidmaterial loss
Core Design Contradiction:
ProductivityVSLoss of substance

Solution Approach 1:

The cage is manufactured as multiple smaller segments through injection molding, which reduces material loss and prevents cavity formation compared to molding a complete large cage. The segments are then assembled to form the complete cage, maintaining production scalability while minimizing waste.

Inventive Principle:
Principle #1Segmentation

4Stability of the object's composition

If single-piece cage design is used, then structural integrity is maintained, but shrinkage and dimensional accuracy worsen

Engineering Contradiction:
Improvestructural integrityVSAvoiddimensional accuracy
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The cage is divided into multiple segments that are each manufactured with high dimensional accuracy through injection molding. The segments are then connected using connecting elements that maintain structural integrity while allowing each segment to be precisely manufactured independently, avoiding the shrinkage and accuracy issues of large single-piece molding.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2677184B1Segment of a rolling bearing cage
Publication Date: 2020.08.05 AB SKF SKF PATENT DEPARTMENT
  • EP2677184B1 patent drawingFigure 1~2
  • EP2677184B1 patent drawingFigure 3~5
  • EP2677184B1 patent drawingFigure 6

AI summary

The segment (2,3) has a bar (4), which extends in an axial direction (8) and two side sections (14,16), which are connected with the bar and are arranged on the opposite sides of the bar in the axial direction. Another bar (6) has a slot (10) on the side opposite to the former bar for receiving a rolling body. A connecting element (18,20) is provided for connecting the segments with a further segment of the roller bearing cage. The segment is made of an injection-moldable plastic material of more than 50 percent by volume.