Ultrasonically Welded Two-Piece Bearing Cage for High-Speed Loads
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Solution Overview
Problem
Existing bearing cages struggle to withstand the increased stress from high rotational speeds associated with electric motors while maintaining economical manufacturing costs.
Innovation Solution
A two-piece bearing cage design with ultrasonically welded posts and holes, where the posts are plastically deformed to fill wider portions, retaining balls between the cage halves and maintaining rolling contact with inner and outer races, and a method of assembly using ultrasonic vibration to join the cage halves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional bearing cage designs are used, then manufacturing costs are reduced, but the cage cannot withstand high-speed centrifugal loads
Solution Approach 1:
The cage is divided into two separate halves that are assembled together, allowing each half to be manufactured independently using cost-effective processes while achieving the structural integrity needed for high-speed applications through the integration of ultrasonic welding and plastic deformation
Solution Approach 2:
The material state of the posts is changed through plastic deformation during assembly, transforming them from a formable state to a locked state that provides the necessary strength to withstand centrifugal loads at high speeds
2Reliability
If the cage is designed to withstand high speeds, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The posts are pre-formed with a specific geometry that includes a narrower section and a wider section, allowing them to be inserted through the holes and then deformed in a controlled manner during the ultrasonic welding process to achieve the locked configuration
Solution Approach 2:
Traditional mechanical fastening methods are replaced with ultrasonic welding, which uses vibration energy to join the cage halves and deform the posts simultaneously, simplifying the assembly process while ensuring reliable operation at high speeds
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 solution provides a robust and cost-effective bearing cage capable of withstanding high-speed centrifugal loads, ensuring reliable operation in high-speed applications such as electric traction motors.
Implementation Method 1
using ultrasonic vibration to join the cage halves. The first cage half has a plurality of posts. The second cage half defines a plurality of holes. The first cage half and the second cage half are brought together such that the posts extend through the holes. Subjecting ends of the posts to ultrasonic vibration joins the cage halves. The ultrasonic vibration may weld the ends of the posts to the second cage half.
Implementation Method 2
Each of the holes may have a narrow portion adjacent to the first cage half and a wider portion. The posts may have been plastically deformed to fill the wider portion.
Data Source
AI summary
A two-piece plastic ball bearing cage is designed to handle high-speed applications. Posts on one bearing half fit into holes in the other bearing half After the two halves are brought together, ultrasonic vibration is applied to the ends of the posts. The ultrasonic vibration deforms the post end to fit into a widened portion of the holes and welds material, thereby firmly securing the two cage halves to one another.