Multi-Sprocket Carrier Assembly Using Friction Stir Welding
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Solution Overview
Problem
Existing methods for forming multi-sprocket cogs in bicycles are laborious and time-consuming, such as requiring aligned pin holes or costly and time-consuming 5-axis machining.
Innovation Solution
A sprocket assembly is formed using a carrier and sprockets coupled via solid-state welding, specifically friction stir welding, where the carrier extends into central through holes of the sprockets, allowing for efficient and cost-effective assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sprockets are interconnected by pins with aligned pin holes, then the assembly is straightforward, but the process is laborious and time-consuming
Solution Approach 1:
The patent merges the sprocket body and mounting hub into a single integrally formed component. This eliminates the need for separate pins and pin holes, allowing the sprocket to be directly mounted onto the carrier hub as one piece, thereby resolving the contradiction between ease of manufacture and assembly speed
2Strength
If sprockets are integrally formed from a truncated cone via 5-axis machining, then the structural integrity is improved, but the process is costly and time-consuming
Solution Approach 1:
The patent segments the sprocket assembly into two main parts: the integrally formed sprocket body (providing structural integrity) and the separate carrier hub (providing mounting functionality). This segmentation allows each component to be optimized independently and assembled together, resolving the contradiction between structural integrity and manufacturing efficiency
3Manufacturing precision
If multiple sprockets are assembled with precise pin hole alignment, then the positional accuracy is achieved, but the manufacturing complexity increases
Solution Approach 1:
By merging the sprocket body and hub into an integral structure, the patent eliminates the need for separate alignment of pin holes between multiple components. The integral design ensures positional accuracy is built-in during forming, while reducing assembly complexity to a single mounting operation
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 assembly process is streamlined, reducing time and cost while enabling material selection for optimized properties like weight, structural strength, and thermal conductivity.
Implementation Method 1
at least one of the sprockets is coupled to the carrier by a weld that is formed via a solid-state welding technique
Data Source
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AI summary
A sprocket assembly (118, 120, 300, 302, 1200) includes a carrier (400, 1202) and a plurality of sprockets (402). The carrier (400, 1202) has a central axis. Each of the sprockets (402, 404, 406, 408) has a different number of teeth and is formed with a central through hole (542, 544, 546, 548). The carrier (400, 1202) extends into the central through hole (542, 544, 546, 548) of each of the sprockets (402, 404, 406, 408) such that the sprockets (402, 404, 406, 408) are disposed on an outer periphery of the carrier (400, 1202) and are disposed along the central axis. At least one of the sprockets (402, 404, 406, 408) is coupled to the carrier (400, 1202) by a weld (800) that is formed via a solid-state welding technique.