Furniture Cam Coupling with Expanding Tie-Rod Alignment

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Solution Overview

Problem

Existing coupling devices for furniture suffer from high costs due to processing technology, material quality and quantity, alignment difficulties, and low mechanical resistance, requiring larger dimensions and more material, with the cam subject to axial and transverse stresses and incorrect alignment.

Innovation Solution

A coupling device comprising a tie-rod, cam, and expanding element made of metal through cold deformation technology, featuring a tapered portion with helicoidal teeth for alignment, a cylindrical cam with radial slots for easy assembly, and an expanding element with notches for secure positioning, allowing axial stress only and reducing material usage and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the cam is made of zamak die-casting or plastic material to obtain project geometries, then the manufacturing cost is reduced, but the mechanical resistance is low requiring larger dimensions and significant material usage

Engineering Contradiction:
Improvemanufacturing costVSAvoidmechanical resistance
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The invention uses a metal cam body (providing mechanical strength) combined with a plastic insert (providing geometric precision and ease of manufacture). This composite structure allows the cam to maintain high mechanical resistance while keeping manufacturing costs low and geometries precise.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention changes the material parameters by selecting high-strength metal for the cam body instead of low-strength zamak or plastic, thereby reducing the required dimensions while maintaining or improving mechanical resistance.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the tie-rod is screwed onto the shoulder of the piece of furniture or into an additional bush, then the connection is secure, but the assembly time increases and alignment becomes difficult

Engineering Contradiction:
Improveconnection securityVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The invention replaces the traditional screw-threaded connection system with a press-fit expansion system. The tie-rod has an expanded end that is inserted into a hole and then expanded to create a firm connection, eliminating the need for screws and threading operations.

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

Solution Approach 2:

The tie-rod's expanded end automatically creates its own anchoring mechanism by being inserted into a hole and then expanded. The expansion process itself creates the securing force, making the system self-securing without requiring additional fastening components or complex alignment procedures.

Inventive Principle:
Principle #25Self-service

3Strength

If the cam has a double cam (fork) to connect with the tie-rod, then the axial thrusts are resisted, but the dimensions must be larger

Engineering Contradiction:
Improveaxial thrust resistanceVSAvoidcam dimensions
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The metal cam body provides the necessary strength to resist axial thrusts, eliminating the need for a double-cam fork structure. The metal material's inherent strength allows for a more compact single-cam design while maintaining the same load-bearing capacity.

Inventive Principle:
Principle #40Composite materials

4Strength

If the tie-rod is made with complex processing technology, moulded steel, turning, or aluminium die-casting, then the mechanical properties are improved, but the manufacturing cost increases

Engineering Contradiction:
Improvemechanical propertiesVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The invention changes the manufacturing parameters by using simpler, more cost-effective processes such as punching and bending for the metal tie-rod, instead of complex processes like moulded steel, turning, or aluminium die-casting. The design is optimized to be manufacturable with these simpler processes while maintaining adequate mechanical properties.

Inventive Principle:
Principle #35Parameter changes

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 solution provides a rapid, cost-effective, and robust coupling system with improved alignment precision, reduced material usage, and enhanced mechanical resistance, enabling assembly without screws and using thinner panels with equal holding strength, while minimizing visual impact and material perforation.

Implementation Method 1

an expanding element (14) which can be inserted in the tie-rod (12), having an enlarged end (31) suitable for being positioned inside the first portion (15) causing its expansion and therefore a stable positioning

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2705260A2Coupling device for furniture and furnishing articles
Publication Date: 2014.03.12 D EFFE

AI summary

A coupling device for furniture and furnishing articles positioned between a shoulder (18) and a base (21) of a piece of furniture, comprising, in combination, a tie- rod element (12), a cam element (13) and an expanding element (14) which can be inserted in the tie-rod element (12), said tie-rod element (12) and said cam element (13) having an essentially cylindrical shape with main axes (X and Y) perpendicular to each other and intersecting inside respective holes (20) and (26) of the base (21) of the piece of furniture, all three of said elements (12, 13, 14)' being made of metal or metal alloys produced through the plate and/or wire cold deformation technology, the tie-rod element (12) and the cam element (13) comprising reciprocal tightening means by the activation of the cam element (13).