Bicycle Front Fork Crown Assembly Using Friction Stir Welding

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Solution Overview

Problem

Existing bicycle front fork assembly techniques, such as press fitting, often result in unpredictable deformation and stress due to high forces, leading to misalignment and increased manufacturing complexity and costs.

Innovation Solution

The use of a solid-state welding process, 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 that reduces deformation and stress, enabling more precise and predictable assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If press fitting is used to couple the steerer tube and crown, then the components can be assembled, but unpredictable deformation and stress occur leading to misalignment

Engineering Contradiction:
Improveassembly processVSAvoidalignment
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical press fitting system with a welding system. Instead of using high mechanical forces to force components together, the invention uses welding to create a permanent bond between the steerer tube and crown, eliminating the deformation and misalignment issues associated with press fitting while maintaining assembly effectiveness

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If press fitting is used to couple the steerer tube and crown, then assembly can be completed, but high forces cause unpredictable deformation and stress

Engineering Contradiction:
Improveassembly efficiencyVSAvoidcomponent stress
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent substitutes the high-force mechanical press fitting process with a welding process. This replacement eliminates the need for unpredictable high forces while maintaining assembly effectiveness, thereby improving reliability by reducing component stress and deformation

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If press fitting is used to couple the steerer tube and crown, then the components are joined, but manufacturing complexity and costs increase

Engineering Contradiction:
Improveassembly capabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent replaces the complex press fitting process with a simpler welding process. By eliminating the need for high-force mechanical assembly equipment and the associated complexity of controlling press fit tolerances, the invention reduces manufacturing complexity while maintaining the ability to join components effectively

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 approach results in a more reliable, cost-effective, and efficient assembly process with improved alignment and reduced stress on components, leading to better performance and manufacturing efficiency.

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.

Methodology Applied
Scientific EffectSolid-state welding: Welding

Implementation Method 2

The use of a solid-state welding process, specifically friction stir welding, to couple the steerer tube and crown of the front fork

Methodology Applied
Scientific EffectFriction stir welding: Friction Welding

Data Source

PatentEP4361012A1Front forks for bicycles
Publication Date: 2024.05.01 SRAM LLC
  • EP4361012A1 patent drawingFigure 1
  • EP4361012A1 patent drawingFigure 2~3
  • EP4361012A1 patent drawingFigure 4

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.