Noncircular Stool Seat Support to Prevent Bolt Shearing
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Solution Overview
Problem
Conventional stool seating with circular seat posts and mounts can lead to damage and safety hazards due to twisting, as occupants can shear off the securing bolts, causing the seat to spin and potentially result in injury or wear, especially when plastic seats are attached to metallic posts.
Innovation Solution
A seating apparatus featuring a seat post and support mount with noncircular cylindrical surfaces, such as square or polygonal cross sections, that align to prevent rotational movement, ensuring the stresses from twisting are borne by the seat and post rather than the bolt, thereby preventing bolt shearing and spinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a circular seat post and support mount are used with a bolt securing mechanism, then the stool can be easily manufactured and assembled, but the bolt can be sheared off by twisting, causing safety hazards and requiring repair or replacement
Solution Approach 1:
The patent applies asymmetry by changing the circular cross-section of the seat post and support mount to a noncircular shape (such as square, rectangular, or other polygonal forms). This asymmetric geometry prevents rotational movement of the seat relative to the seat post, eliminating the twisting action that causes bolt shearing. The noncircular surfaces mate together to provide inherent anti-rotation capability while maintaining ease of manufacture through standard fabrication processes.
2Device complexity
If a bolt is used to secure the seat post to the support mount, then the assembly is simple and cost-effective, but the bolt becomes a weak point that can fail under repeated twisting loads
Solution Approach 1:
The asymmetric noncircular cross-section design eliminates the need for additional anti-rotation mechanisms. The geometry itself provides the constraint against rotational movement, making the bolt's only function to maintain axial positioning and preload. This reduces the harmful twisting forces on the bolt while keeping the overall device complexity low.
Solution Approach 2:
The noncircular surfaces are designed to mate together before the bolt is fully tightened, establishing the anti-rotation constraint in advance. This preliminary geometric constraint prevents twisting from occurring during use, protecting the bolt from shear forces before they can accumulate to dangerous levels.
3Adaptability or versatility
If the seat is allowed to spin on the seat post, then occupants might use the stool for recreation, but this creates dangerous conditions including potential injury from falling or impalement
Solution Approach 1:
The noncircular cross-section design inherently prevents rotational movement, eliminating the possibility of the seat spinning on the seat post. This geometric constraint addresses the safety hazard by making rotation mechanically impossible, while still allowing the stool to serve its primary seating function. The design maintains adaptability for various seating applications without introducing harmful rotational freedom.
Data Source
AI summary
An improved seating apparatus is provided, including a seat supported by a fixed seat post, the seat post mating with a support mount fixed to the bottom of the seat. The aligned surfaces of the seat post and support mount are of a non-circular cylindrical shape to prevent rotation of the support mount with respect to the seat post.