Chair and frame assembly thereof

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Solution Overview

Problem

Existing chair manufacturing methods using mesh as a back support member face challenges such as poor productivity, unstable yields, and potential separation due to manual tensioning and mesh elasticity, especially on complex curved surfaces.

Innovation Solution

A frame assembly design featuring a first and second frame with protruding ribs and grooves, a sheet with fixed regions, and a covering member that automates the stretching process, ensuring durability and ergonomic support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If manual tensioning method is used to make the mesh taut on the complex curved back surface, then the mesh can be stretched to fit the shape, but the productivity is poor and the yield is unstable due to dependence on worker skill and effort

Engineering Contradiction:
Improvemesh tensioning uniformityVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces the manual mechanical tensioning system with an automated injection molding system. The mesh is integrated into the mold cavity, and hydraulic or mechanical pressure from the injection molding process automatically tensions and secures the mesh to the complex curved back surface, eliminating dependence on worker skill and dramatically improving both precision and productivity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The mesh is pre-positioned and pre-tensioned during the mold closing stage before injection. The mold structure includes predetermined tensioning elements that automatically apply the correct tension to the mesh as it is being formed, ensuring uniform tensioning is achieved as part of the normal molding process rather than as a separate manual operation

Inventive Principle:
Principle #10Preliminary action

2Shape

If manual tensioning method is used to make the mesh taut, then the mesh can be stretched to fit the complex curved surface, but the frame components may separate due to the elasticity of the net

Engineering Contradiction:
Improvecomplex curved surface fitVSAvoidframe component separation
Core Design Contradiction:
ShapeVSStability of the object's composition

Solution Approach 1:

The patent merges the mesh layer with the frame structure by integrating the mesh into the injection molding process. The mesh is positioned within the mold cavity and becomes structurally integrated with the plastic frame material that is injected around it, creating a unified composite structure where the mesh and frame work together as a single stable unit

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The injection molded plastic material acts as an intermediary that bonds the mesh to the frame structure. This plastic matrix secures the mesh in place, distributing the elastic forces uniformly across the frame and preventing component separation while maintaining the complex curved shape

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If various stretching methods are used for the mesh, then different manufacturing approaches can be explored, but the manufacturing difficulty and durability vary significantly

Engineering Contradiction:
Improvemanufacturing method varietyVSAvoidmanufacturing difficulty
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The injection molding process serves multiple functions simultaneously: it forms the frame structure, tensions the mesh, secures the mesh to the frame, and creates the complex curved geometry. This multi-functional approach consolidates what would otherwise require multiple separate manufacturing steps into a single automated process, improving ease of manufacture while maintaining versatility

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enables automated production of durable chairs with ergonomic support, maintaining tensile strength and preventing frame separation, while adapting to complex curved shapes.

Implementation Method 1

the second regions are bent under combined pressure of the first frame and the second frame

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4646971A1Chair and frame assembly thereof
Publication Date: 2025.11.12 CHEN HSIN HUA
  • EP4646971A1 patent drawingFigure 1
  • EP4646971A1 patent drawingFigure 2
  • EP4646971A1 patent drawingFigure 3

AI summary

A chair includes a frame assembly having a first side and a second side opposite each other. The frame assembly includes a first frame, a second frame, a sheet, and a covering member. The first frame has a first opening facing the first side. The second frame includes two opposite fixing portions and a second opening. The second opening faces the second side and overlaps the first opening in position. The sheet includes two opposite first regions, two opposite second regions, and a third region located between the second regions, the second regions are bent under combined pressure of the first frame and the second frame, and the third region is exposed between the first opening and the second opening. The covering member covers the first frame and the second frame and exposes the first opening, the second opening, and the third region.