Indexed Hinge Assembly for Wear-Resistant Watch Joints
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Solution Overview
Problem
Small hinges used in watchmaking and jewelry face issues with inadequate fatigue resistance, torsional stresses, and wear, particularly when made from materials like gold and platinum alloys, and often require oversizing to manage bending stresses, which is not compatible with luxury pieces.
Innovation Solution
A hinge assembly design featuring an external hinge with a first and second yoke, and an internal hinge with a single yoke, using a guide tube and tube-nut arrangement with angular indexing means and low-friction materials like polyamide or polytetrafluoroethylene to distribute stress and reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the hinge size is increased to improve fatigue resistance and strength, then the bending stress resistance is improved, but the compatibility with watch or jewelry components is worsened due to size constraints
Solution Approach 1:
The hinge is divided into two separate hinges (first hinge and second hinge) that are articulated relative to each other, allowing each hinge to be smaller while maintaining overall strength through the articulated configuration
Solution Approach 2:
The invention uses a tube-nut made of polyamide material (PA11 or PA6-6) with embedded steel fibers, combining the low friction and corrosion resistance of polyamide with the high strength of steel fibers to achieve both small size and high fatigue resistance
2Device complexity
If a traditional screw and nut arrangement is used to secure the hinges, then the assembly is simplified, but torsional stresses cause rapid wear in the bores of the clevises
Solution Approach 1:
The traditional metal screw and nut arrangement is replaced with a polyamide tube-nut containing embedded steel fibers, reducing torsional stress and friction while maintaining securing functionality
Solution Approach 2:
The tube-nut is made of polyamide material (PA11 or PA6-6) with embedded steel fibers, combining the low friction and corrosion resistance of polyamide with the high strength of steel fibers to resist wear from torsional stresses
3Ease of manufacture
If precious materials like gold and platinum alloys are used for the hinge, then the aesthetic quality is improved, but the wear resistance is worsened
Solution Approach 1:
The tube-nut is made of polyamide material (PA11 or PA6-6) with embedded steel fibers, combining the low friction and corrosion resistance of polyamide with the high strength of steel fibers to resist wear while allowing precious materials to be used for aesthetic components
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 provides enhanced resistance to bending and torsion, reducing wear and ensuring long-term operational safety for high-end watchmaking and jewelry applications.
Implementation Method 1
making of the guide tube and/or the tube-nut in polyamide 11 or in polyamide 6-6 or in polytetrafluoroethylene or in high density polyethylene
Data Source
Figure 1
AI summary
One aspect of the invention relates to a watchmaking or jewelry hinge assembly (100) comprising an external hinge (1) with a first and a second yoke (11, 110) and an internal hinge (2) with a single yoke (21), pivoting around a screw (5) passing through a guide tube (4) insertable and rotationally indexed in the first yoke (11) and a nut-tube (3) insertable in the second yoke (110), and axially immobilized by a head (51) in the guide tube (4) and comprising a thread (55) cooperating with a tapped hole (35) in the nut-tube (3), for adjusting the axial play or tightening between the external hinge (10) and the internal hinge (20), the nut-tube (3) being rotationally indexable in the second yoke (110), the nut-tube (3) or the guide tube (4) advantageously being made of polyamide 11 or of polytetrafluoroethylene or high-density polyethylene.