Bicycle Front Fork Crown Assembly Using Friction Stir Welding
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Solution Overview
Problem
Existing front fork assembly techniques for bicycles result in unpredictable deformation and alignment issues due to high pressing forces during press fitting, leading to permanent stresses and difficulty in achieving precise component alignment.
Innovation Solution
The use of solid-state welding, specifically friction stir welding, to couple the steerer tube and crown of the front fork, eliminating the need for press fitting and allowing for a transition fit, which reduces bending forces and ensures predictable alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If press fitting is used to couple the steerer tube and crown, then the components can be assembled, but high pressing forces cause unpredictable deformation and alignment issues
Solution Approach 1:
The patent replaces the mechanical press fitting system with a welding system. Instead of using high pressing forces to couple the steerer tube and crown, the invention uses welding to create a permanent bond, thereby eliminating the deformation and alignment issues caused by mechanical pressing forces
Solution Approach 2:
The patent changes the coupling parameter from mechanical pressing to thermal welding. By transitioning from a mechanical assembly process to a thermal joining process, the invention achieves precise alignment without the harmful effects of high pressing forces
2Ease of manufacture
If press fitting is used to couple the steerer tube and crown, then assembly can be achieved, but permanent stresses are induced in the components
Solution Approach 1:
The patent replaces the mechanical press fitting system with a welding system. Instead of using high pressing forces to couple the steerer tube and crown, the invention uses welding to create a permanent bond, thereby eliminating the deformation and alignment issues caused by mechanical pressing forces
3Strength
If traditional welding is used to join the steerer tube and crown, then strong bonding is achieved, but the heat-affected zone causes material property changes
Solution Approach 1:
The patent changes the welding parameter from fusion welding to solid-state welding. By using friction stir welding instead of traditional fusion welding, the invention achieves strong bonding without creating a heat-affected zone, thereby maintaining precise control over material properties
Solution Approach 2:
The patent utilizes the phase transition of the material during friction stir welding, where the material undergoes solid-state transformation through friction heat and mechanical stirring, creating a strong bond without melting and subsequent cooling that would create a heat-affected zone
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 method results in more precise manufacturing and assembly, reducing manufacturing time and costs while maintaining structural integrity and alignment of the steerer tube and legs, eliminating deformation and stress on the crown.
Implementation Method 1
The steerer tube and the crown coupled by a weld at or near the bottom side of the crown. The weld is formed by a solid-state welding process.
Implementation Method 2
The use of solid-state welding, specifically friction stir welding, to couple the steerer tube and crown of the front fork
Data Source
AI summary
Example front forks for bicycles are described herein. An example front fork includes a crown having a top side and a bottom side opposite the top side. The crown defines an opening between the top side and the bottom side. The front fork includes a first leg and a second leg coupled to and extending from the bottom side of the crown. The front fork also includes a steerer tube disposed in the opening of the crown and extending from the top side of the crown. The steerer tube and the crown coupled by a weld at or near the bottom side of the crown.