Movable Relay Terminal Geometry for Roll-Mark Fatigue Resistance
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Solution Overview
Problem
Relays with movable terminals manufactured by rolling processes are prone to breaking due to roll marks extending perpendicular to the elastic displacement direction, leading to reduced mechanical reliability and shortened lifespan.
Innovation Solution
The movable terminal is designed with an insertion part that has frustums or elongated frustums formed on the insertion part, with the bottom edge of these features inclined at a non-zero angle relative to the direction of the roll marks, reducing the length of the edge parallel to the roll marks and acting as a fulcrum, thereby minimizing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the movable terminal is manufactured by a rolling process with roll marks extending perpendicular to the elastic displacement direction, then the crystal structure extends in the direction of the roll marks making cracking unlikely during bending, but the bottom edge acting as a fulcrum causes the movable terminal to easily break during repeated elastic deformation
Solution Approach 1:
The bottom edge of the insertion part is given a specific geometric shape (convex, concave, or inclined) to create localized structural characteristics that differ from the rest of the movable terminal. This local structural modification reduces stress concentration at the bottom edge, preventing breakage during repeated elastic deformation while maintaining the overall rolling process manufacturing method
Solution Approach 2:
The bottom edge is designed with asymmetric features such as convex portions, concave portions, or inclined surfaces rather than a straight edge. This asymmetric geometry distributes stress more effectively during the pressing operation, reducing the likelihood of breakage at the fulcrum point while preserving the roll mark orientation for cracking resistance
2Reliability
If the direction of the roll marks is changed to be parallel to the elastic displacement direction, then the movable terminal would be less likely to break during repeated deformation, but the shape processing requirements and cost per unit increase
Solution Approach 1:
Instead of changing the overall roll mark direction, only the bottom edge geometry is modified locally. This allows the main body of the movable terminal to maintain roll marks perpendicular to the displacement direction (satisfying manufacturing efficiency), while the localized bottom edge modification provides the reliability improvement needed for repeated deformation
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 mechanical reliability of the movable terminal, reducing the likelihood of breakage and extending the relay's life by stabilizing the press-fitting operation and improving contactability.
Implementation Method 1
A relay has an electromagnet, an armature configured to be movable relative to the electromagnet by magnetic force
Implementation Method 2
the movable terminal has a movable contact facing the fixed contact across a gap and elastically deforms with the base block, etc., as a fulcrum
Data Source
AI summary
A relay having improved mechanical reliability of a movable terminal having rolled marks and an extended life span is provided. The relay has a base block and a movable terminal positioned in the base block and having rolled marks. The movable terminal has an insertion part inserted into the base block, a movable contact elastically displaceable in a direction substantially perpendicular to a direction of the rolled marks with the insertion part as a fulcrum, and a plurality of frustums formed on the insertion part and abutting against the base block.