One-Sided Fastener Assembly Tapered Core Interference Fit
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Solution Overview
Problem
Existing fastening systems require manipulation from both sides, leading to high labor costs and ergonomic issues, or complex robotic setups, and struggle with weight, aerodynamic flushness, and manufacturing complexity, especially with one-sided fasteners that use large bulbs for mechanical benefit.
Innovation Solution
A one-sided fastener assembly featuring a sleeve with an inner tapered surface and a core with an outer tapered surface, where the core is inserted to cause radial expansion of the sleeve, creating an interference fit with the assembly stack-up, allowing for flush installation and interference fit without the need for dual-sided manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large bulb is added to the backside of the assembly for mechanical benefit, then the mechanical strength is improved, but the weight of the assembly increases significantly
Solution Approach 1:
The patent changes the geometric parameters of the fastener by using a tapered core instead of a large bulb, transforming the distribution of material to achieve mechanical strength through interference fit and taper geometry rather than bulk mass
Solution Approach 2:
The fastener uses a composite structure with a tapered core and a sleeve, combining two components with different functions - the core provides the interference fit mechanism while the sleeve provides the structural interface with the assembly
2Device complexity
If a one-sided fastener design is used to reduce complexity, then the device complexity is reduced, but the manufacturing precision requirements increase due to interference fit tolerances
Solution Approach 1:
The tapered geometry of the core provides self-aligning characteristics that accommodate minor variations in hole positioning and sleeve tolerance, reducing the stringency of manufacturing precision requirements while maintaining the one-sided simple structure
3Reliability
If dual-sided fastener manipulation is used to achieve secure fastening, then the reliability of fastening is improved, but the labor cost and operational complexity increase
Solution Approach 1:
The fastener system is designed to be self-servicing from one side only - the tapered core automatically expands the sleeve through interference fit when inserted, eliminating the need for manipulation from both sides while maintaining secure fastening reliability
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 reduces labor costs, enhances flushness control, and simplifies installation by using a tapered geometry and material selection to create a secure interference fit, suitable for fatigue-related joints, while minimizing weight and manufacturing complexity.
Implementation Method 1
insertion of the core into the sleeve causes radial expansion of the sleeve creating an interference fit with the assembly stack-up
Data Source
AI summary
A one-sided fastener assembly for use in coupling an assembly stack-up includes a sleeve comprising an outer cylindrical surface and an inner tapered surface oriented at a first angle with respect to the outer surface. The inner tapered defines an opening extending through the sleeve. The fastener assembly also includes a core extending along an axis and configured for insertion into the opening. The core includes an outer tapered surface oriented at a second angle with respect to the axis configured for engagement with the sleeve inner tapered surface such that insertion of the core into the sleeve causes radial expansion of the sleeve creating an interference fit with the assembly stack-up to complete installation of the one-sided fastener assembly.