Adjustable Height Stool Spindle Connection to Prevent Wobbling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional adjustable height stools experience looseness over time due to repetitive adjustments, leading to wobbling and uneven stress distribution, which affects reliability and user comfort.
Innovation Solution
An anti-wobbling adjustable height stool design featuring a threaded seat support spindle with a cone-shaped spindle head and a rubber pad with a fitting recess, providing a tight fit and interference fit to prevent wobbling, along with a nut and outer tube assembly to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a screw connecting a stool seat penetrates a screw hole in a stool base for height adjustment, then the height can be adjusted through repetitive rotations, but a gap develops between the screw and screw hole over time, resulting in wobbling and looseness
Solution Approach 1:
The patent changes the connection parameters from a simple screw-hole penetration to a multi-component system including a connecting frame with installation hole, spindle head with tight fit, and rubber pad with interference fit. These parameter changes transform the connection from loose to stable while preserving adjustability.
Solution Approach 2:
The patent employs composite material connections by combining metal components (connecting frame, spindle head) with elastomeric material (rubber pad). The rubber pad provides both the interference fit for stability and the necessary compliance for adjustment operations, resolving the contradiction between ease of operation and reliability.
2Device complexity
If the screw and screw hole connection is used for height adjustment, then the structure remains simple, but uneven stress is applied to the small contact area, causing the stool seat to loosen and wobble
Solution Approach 1:
The patent segments the connection structure into multiple functional components: connecting frame, spindle head, rubber pad, and outer tube. Each segment performs a specific function - the connecting frame provides the installation hole, the spindle head provides tight fit, the rubber pad provides interference fit and stress distribution, and the outer tube houses the nut. This segmentation allows complex stress distribution while maintaining manageable overall complexity.
Solution Approach 2:
The rubber pad acts as an intermediary element between the metal spindle and the outer tube. It distributes stress evenly across the contact area, prevents stress concentration, and provides the interference fit necessary for stability. This intermediary component resolves the stress distribution problem while keeping the overall structure relatively simple.
3Stability of the object's composition
If a conventional screw connection is used, then the initial connection is tight, but repetitive adjustments cause gap formation and wobbling over time
Solution Approach 1:
The rubber pad is installed beforehand to provide cushioning and compensation for the connection. It anticipates the wear and gap formation that would occur with repetitive adjustments, maintaining the interference fit and preventing wobbling throughout the product's service life. This beforehand cushioning ensures both initial tightness and long-term durability.
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 design ensures a stable and reliable connection between the stool seat and adjusting screw, preventing looseness and wobbling, enhancing user comfort and safety by distributing weight evenly and preventing the stool from shifting.
Implementation Method 1
a bottom of the adjusting screw being installed in the fitting recess and in interference fit with the rubber pad
Implementation Method 2
a movable gap ranging from 0.070 mm to 0.250 mm being formed between an outer wall of the rubber pad and an inner wall of the outer tube
Data Source
AI summary
An anti-wobbling adjustable height stool includes an adjusting screw vaving a threaded seat support spindle and a top spindle head and a stool seat assembly. The stool seat assembly includes a stool seat, and a connecting frame connected with a bottom of the stool seat. The connecting frame is opened with an installation hole, and the spindle head penetrating through and being arranged in the installation hole to enable a tight fit of the spindle head with the connecting frame.