Adhesive Bonded Coil Spring End Caps for Nitrided Steel
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Solution Overview
Problem
Existing coil spring assemblies with press-fit end caps face issues such as dead coil turns not contributing to the spring rate due to fixed contact, and press-fitting is unsuitable for nitrided coil springs, which can crack under pressure.
Innovation Solution
A coil spring assembly with end caps adhered using adhesives, allowing the coil springs to expand or contract without interference, and using centering protrusions to maintain alignment, reducing the number of dead coil turns and enabling the use of higher-grade materials like nitrided steel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If press-fit end caps are used to fix coil springs, then the end caps are securely attached, but the dead coil turns cannot expand or contract, preventing them from contributing to the spring rate
Solution Approach 1:
The patent introduces an adhesive as an intermediary substance between the end cap and the coil spring. This adhesive mediator allows the end cap to be securely attached while permitting the dead coil turns to expand and contract, thus contributing to the spring rate. The adhesive layer accommodates the dimensional changes of the spring during operation without creating the rigid constraint that prevents spring rate contribution.
2Strength
If press-fitting end caps onto nitrided coil springs is performed, then secure attachment is achieved, but the pressure causes cracking of the coil turns
Solution Approach 1:
The patent replaces the mechanical press-fit attachment system with a chemical adhesive bonding system. Instead of applying mechanical pressure that cracks the nitrided coil springs, the adhesive provides secure attachment through chemical bonding. This substitution eliminates the harmful mechanical stress while maintaining or improving the attachment strength between end caps and coil springs.
3Strength
If dead coil turns are fixed to end caps with press-fit, then the end caps are firmly secured, but the number of effective spring turns is reduced
Solution Approach 1:
The adhesive acts as a mediator that secures the end cap to the coil spring while allowing the dead coil turns to remain part of the active spring system. The adhesive bond provides firm fixation of the end cap without creating the rigid constraint that would prevent the dead coil turns from contributing to spring rate, thus maximizing the number of effective spring turns.
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 spring rate and performance by reducing mass and hysteresis, allowing for the use of higher-grade materials and minimizing stress-related issues, while maintaining a smaller mass for the end caps.
Implementation Method 1
a first end cap fixedly connected to the first longitudinal end with a first adhesive; and a second end cap fixedly connected to the second longitudinal end with a second adhesive
Data Source
AI summary
A coil spring assembly, including: a coil spring with a first longitudinal end and a second longitudinal end; a first end cap fixedly connected to the first longitudinal end with a first adhesive; and a second end cap fixedly connected to the second longitudinal end with a second adhesive. A method of fabricating a coil spring assembly, including: fixedly connecting, with a first adhesive, a first end cap to a first longitudinal end of a coil spring; and fixedly connecting, with a second adhesive, a second end cap to a second longitudinal end of the coil spring.