Split-Tongue Miter Joint for Panel-Shaped Element Corner Stability

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Solution Overview

Problem

Existing miter couplings for panel-shaped elements in furniture and similar applications lack sufficient stability, strength, and ease of installation, particularly when made from thin, brittle materials like particle board.

Innovation Solution

The proposed solution involves a locking tongue and groove connection with an eccentrically arranged tongue, which is cut free on one side to enhance flexibility, and a protruding lip on the groove to create additional contact surfaces beyond the theoretical miter line, improving support and locking strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a conventional miter coupling is used to join panel-shaped elements, then the assembly process is simple, but the connection lacks sufficient stability and strength, especially with thin, brittle materials

Engineering Contradiction:
Improveconnection strengthVSAvoidcoupling structure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The coupling system is divided into separate tongue and groove components with distinct functions. The tongue includes a locking element that engages with the groove, creating a segmented structure that provides both simplicity of assembly and enhanced connection strength through dedicated locking functionality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The tongue is positioned eccentrically relative to the groove, creating an asymmetric configuration. This asymmetry enables the locking element to engage effectively with the groove while maintaining structural integrity, resolving the contradiction between simple assembly and strong connection by distributing forces unevenly across the joint.

Inventive Principle:
Principle #4Asymmetry

2Stability of the object's composition

If a locking tongue and groove connection is used to enhance stability, then the connection strength improves, but the assembly process becomes more complex and difficult to install

Engineering Contradiction:
Improvecorner connection stabilityVSAvoidassembly ease
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The locking element on the tongue is designed to engage with the groove automatically through a snap-fit mechanism. This self-service feature allows the corner connection to achieve stable locking without requiring additional fasteners, tools, or complex assembly steps, thereby maintaining ease of operation while enhancing stability.

Inventive Principle:
Principle #25Self-service

3Strength

If the tongue is made rigid to ensure locking strength, then the connection becomes more stable, but the tongue is more prone to breakage during assembly with brittle materials

Engineering Contradiction:
Improvelocking strengthVSAvoidresistance to breakage
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The tongue exhibits local quality variations: it has a rigid section that provides locking strength when engaged with the groove, and a more flexible section that reduces stress concentration during assembly. This localized differentiation of mechanical properties allows the tongue to maintain locking strength while resisting breakage in critical areas.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The tongue geometry incorporates rounded corners and gradual transitions that cushion stress concentrations before they can propagate into cracks. This beforehand cushioning design prevents brittle failure during assembly by distributing mechanical stresses evenly throughout the tongue structure.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP2811862B1Composed element and corner connection applied herewith
Publication Date: 2025.04.09 UNILIN BVBA
  • EP2811862B1 patent drawingFigure 1~2
  • EP2811862B1 patent drawingFigure 3~6
  • EP2811862B1 patent drawingFigure 4~5

AI summary

Composed element and corner connection applied herewith. Composed element, with at least two wood-based panel-shaped elements (2a, 2b); wherein said panel-shaped elements (2a, 2b) can be coupled to each other at an angle and with a miter joint by means of a locking tongue (8) and groove (9) connection; wherein the tongue (8) consists of a split tongue, with thus at least a first tongue portion and a second tongue portion, as well as a slit (12) situated there between; characterized in that said slit (12), seen in cross-section, globally extends according to a direction (L2) which deviates from the direction of the center line (Ma) of the panel-shaped element on which the tongue is provided.