Wobblefram Corrugations for Micro Switch Fatigue Life
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Solution Overview
Problem
Existing wobblefram designs in micro switches suffer from fatigue cracking below 50,000 cycles, limiting their operational lifespan and requiring complex adjustments to maintain performance characteristics, necessitating a method to enhance fatigue life by at least a factor of six without affecting the switch's operating characteristics.
Innovation Solution
A wobblefram with circular and/or sinusoidal corrugations is formed using a punch and die at elevated temperatures, and an external lever is brazed to the solid center region, with finite element analysis (FEA) optimizing the profile, number, and height of corrugations to extend the wobblefram's lifespan while maintaining rotational stiffness and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a flat-face wobblefram design is used, then the manufacturing process is simple, but the fatigue life is limited to below 50,000 cycles
Solution Approach 1:
The patent applies curvature by introducing circular and sinusoidal corrugations into the wobblefram structure. These curved geometric features redistribute stress during actuation cycles, preventing stress concentration at flat surfaces and thereby extending fatigue life from below 50,000 cycles to over 500,000 cycles while maintaining manufacturing feasibility through punch and die forming at elevated temperatures.
2Duration of action of stationary object
If the wobblefram structure is modified to improve fatigue life, then the operational lifespan increases, but the operating characteristics of the micro switch are affected
Solution Approach 1:
The patent utilizes finite element analysis to optimize specific geometric parameters of the corrugations (profile shape, number of waves, and height) to achieve the desired balance. By carefully controlling these parameters, the design extends fatigue life to over 500,000 cycles while maintaining rotational stiffness and switching performance characteristics identical to the original flat-face design.
3Reliability
If complex adjustments are made to maintain performance characteristics, then the operating performance is maintained, but the manufacturing and adjustment process becomes more complex
Solution Approach 1:
The patent incorporates all necessary performance optimizations into the initial manufacturing process. The corrugated wobblefram is formed with pre-optimized geometric parameters during the punch and die forming process at elevated temperatures, eliminating the need for post-manufacturing adjustments. This preliminary design optimization maintains switching performance while simplifying the overall manufacturing process by removing complex adjustment steps.
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 approach significantly increases the wobblefram's fatigue life to above 500,000 cycles without compromising the micro switch's operating characteristics, achieving a substantial enhancement in durability while maintaining identical rotational stiffness and performance sensitivity.
Implementation Method 1
The flexible circular wobblefram can be formed with a fixed edge and a solid center region by a punch and die at elevated temperatures
Implementation Method 2
An external lever can be brazed to the solid center region of the wobblefram
Data Source
AI summary
A method and apparatus for improving the fatigue life of a wobblefram utilized in a micro switch. The flexible circular wobblefram can be formed with a fixed edge and a solid center region utilizing a punch and die at elevated temperatures. An external lever can be attached to the solid center region of the wobblefram. The lever can be loaded and actuated to transmit motion from outside of the micro switch to a sealed internal mechanism in order to perform a switching function. Circular and/or sinusoidal shaped corrugations can then be added to the wobblefram and evaluated for performance utilizing a finite element analysis (FEA) model. The FEA model can precisely evaluate and optimize profile, number and height of the circular and/or sinusoidal corrugations. Such a wobblefram with circular and/or sinusoidal corrugations can achieve higher lifetime without affecting the operating characteristics of the micro switch.