Spigot Ferrule Joint Geometry for Fishing Rod Stress Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional spigot joint fishing rods experience stress concentration on the spigot ferrule during flexing, leading to potential damage due to bending stress.
Innovation Solution
Incorporating inclined surfaces on the inner peripheral surfaces of the rod bodies at specific angles (1.0° to 3.0°) to distribute bending stress and prevent concentration on the spigot ferrule.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the spigot ferrule is inserted into the rod bodies to joint them, then the rod bodies are connected, but bending stress concentrates on the spigot ferrule causing potential damage
Solution Approach 1:
The patent applies local quality by forming inclined surfaces at specific locations on the rod bodies where they contact the spigot ferrule. These inclined surfaces are localized features that modify the stress distribution precisely at the critical contact points, rather than changing the entire rod structure. The inclination angles of 1.0° to 3.0° are specifically designed to redirect bending stresses away from the spigot ferrule, thereby locally improving the stress distribution and preventing stress concentration.
Solution Approach 2:
The patent employs parameter changes by modifying the geometric parameters of the rod body contact surfaces. By changing the contact surface from a perpendicular orientation to an inclined orientation with specific angles (1.0° to 3.0°), the stress distribution parameters are fundamentally altered. This parameter change transforms the stress concentration problem into a distributed stress condition, significantly improving the bending fracture strength of the spigot ferrule.
2Ease of manufacture
If conventional spigot joint structure is used, then assembly is simple, but stress concentration occurs on the spigot ferrule
Solution Approach 1:
The inclined surfaces are localized modifications to the rod body contact surfaces, maintaining the overall simplicity of the spigot joint assembly while addressing the stress concentration issue. The local quality change is confined to the contact regions, requiring minimal additional manufacturing steps such as machining or forming inclined surfaces at the rod body ends, thus preserving ease of manufacture while improving strength.
Solution Approach 2:
By changing the geometric parameter of the contact surface angle to 1.0° to 3.0°, the patent improves the bending fracture strength without fundamentally altering the assembly process. The inclined surfaces can be integrated into existing manufacturing workflows, maintaining simplicity while achieving the desired strength improvement.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A fishing rod according to one embodiment of the invention includes a small-diameter hollow rod body extending in a central axis direction, a large-diameter hollow rod body extending in the central axis direction, and a spigot ferrule inserted in the small-diameter rod body from its rear end and into the large-diameter rod body from its front end to connect the small-diameter rod body and the large-diameter rod body. In the fishing rod, a first inclined surface that extends from an rear end of the small-diameter rod body at an angle of 0.1° to 10.0° with respect to the central axis direction is formed on an inner peripheral surface of the small-diameter rod body.