Chair Base Understructure with Hoop Ribs for Force Distribution

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Solution Overview

Problem

Existing chair bases concentrate force exertion between the arms and not evenly distribute it throughout the diameter, leading to inefficiencies in material usage and structural integrity.

Innovation Solution

A chair base design with a central hub and radially extending arms, featuring a hoop structure with evenly spaced hoop ribs and cores, X-shaped arm ribs, and variable radii at intersections to distribute forces effectively, reducing material usage while enhancing structural strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If structural strengthening elements are placed centrally to the arms, then the chair base achieves adequate strength, but material usage increases and wall thickness must be maintained

Engineering Contradiction:

Improvevertical and torsional strengthVSAvoidmaterial usage

Core Design Contradiction:

StrengthVSLoss of substance

Solution Approach 1:

The patent applies local quality by placing hoop ribs and hoop cores at specific locations between the arms rather than uniformly throughout. The hoop ribs are positioned to align with force concentration zones, providing localized strengthening where needed while allowing reduced wall thickness in other areas, thus optimizing material distribution.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The structural strengthening is segmented into discrete hoop ribs and hoop cores rather than using a continuous uniform structure. This segmentation allows material to be concentrated where forces are most intense while reducing material in areas experiencing lower stress, resolving the contradiction between strength and material usage.

Inventive Principle:

Principle #1Segmentation

2Reliability

If wall thickness is increased to enhance structural strength, then the chair base achieves better durability, but manufacturing costs increase and cooling efficiency decreases

Engineering Contradiction:

Improvestructural durabilityVSAvoidmanufacturing cost and cooling efficiency

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of uniformly increasing wall thickness throughout the chair base, the patent uses local quality by implementing hoop ribs and hoop cores only in specific regions where structural durability is most critical. This allows the base to meet durability requirements while maintaining thinner walls in non-critical areas, reducing manufacturing costs and improving cooling efficiency during injection molding.

Inventive Principle:

Principle #3Local quality

3Loss of substance

If material usage is reduced to lower costs, then manufacturing becomes more economical, but structural strength may be compromised

Engineering Contradiction:

Improvematerial usageVSAvoidstructural strength

Core Design Contradiction:

Loss of substanceVSStrength

Solution Approach 1:

The patent resolves this contradiction by applying material non-uniformly through hoop ribs and hoop cores positioned where forces concentrate between the arms. This ensures structural strength is maintained in critical load-bearing regions while reducing overall material usage in areas where less support is needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The structure is segmented into regions of high and low material concentration. Hoop ribs and hoop cores create localized reinforcement zones that maintain structural integrity while allowing material reduction in other areas, achieving cost-effectiveness without sacrificing strength.

Inventive Principle:

Principle #1Segmentation

4Productivity

If force distribution is concentrated between the arms, then structural efficiency improves, but uneven force distribution may create stress points

Engineering Contradiction:

Improvestructural efficiencyVSAvoidstress distribution uniformity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent extracts and isolates the force concentration phenomenon by positioning hoop ribs and hoop cores specifically in the zones where forces naturally concentrate between the arms. This targeted approach acknowledges and utilizes the uneven force distribution rather than attempting to uniform it, improving structural efficiency while managing stress through strategic reinforcement.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12582233B2Apparatus and methods for the understructure of a chair base

Publication Date: 2026.03.24 MEDWAY PLASTICS CORP

AI summary

The embodiments relate to a geometric under structure, central and outer hub for a GFN plastic chair base. The geometric shape and dimensions are critical components to the overall strength of the chair base hub and arms when either vertical or rotational forces are applied at the central hub. The central hub is of sufficient thickness to maintain dimensional stability when the forces are applied. The overall geometry and material composition enable the hub area to be constructed with minimal plastic wall thickness while optimizing the physical strength of the article and facilitating high production rate.