Articulated Watch Strap Wear Reduction via High-Hardness Friction Surfaces
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Solution Overview
Problem
Straps with articulated links, particularly watch straps, experience significant wear at joints, leading to increased clearance and unattractive appearance, which existing solutions like jewel bearings fail to adequately address due to fragility and wear caused by abrasive and corrosive conditions.
Innovation Solution
The use of friction surfaces made from pairs of materials with hardness greater than 800 HV, such as ceramic, ceramic-metal composite, amorphous carbon, stainless steel, and precious metal alloys, to reduce wear between joint surfaces, with configurations including sintered or deposited ceramic elements and alternate metal and ceramic layers, and amorphous carbon coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional materials are used for friction surfaces, then ease of manufacture is maintained, but wear resistance deteriorates under corrosive and abrasive conditions
Solution Approach 1:
The patent extracts the bearing function from the metal links by introducing separate friction surface elements made of specialized materials. This allows the main link structure to remain simple and easy to manufacture from conventional materials, while the critical friction surfaces use advanced materials (ceramic, ceramic-metal composite, amorphous carbon coatings) that provide superior wear and corrosion resistance. The separation enables each component to be optimized independently.
Solution Approach 2:
The patent applies local quality by specifying that only the friction surfaces require specialized materials with hardness >800 HV, while other parts of the strap can use conventional materials. The friction surfaces are locally treated or coated with materials such as ceramic layers, ceramic-metal composites, or amorphous carbon, providing enhanced wear and corrosion resistance precisely where needed without complicating the manufacturing of the entire strap structure.
2Shape
If jewel bearings are used to reduce joint clearance, then appearance is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent merges the friction surface function with the existing joint structure by making the friction surfaces integral parts of the joint components. Instead of adding separate jewel bearing elements that increase complexity, the solution integrates high-hardness materials directly into the friction surfaces of the existing joint geometry. This merging approach maintains the simple articulated link structure while achieving reduced wear and maintained appearance through material selection rather than additional 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
Substantially reduces wear between joint surfaces under corrosive and abrasive conditions, as demonstrated by long-term wear tests, maintaining the appearance and durability of the strap.
Implementation Method 1
at least one friction surface of each joint is made from a first material of which the hardness is >800 HV
Implementation Method 2
each of the pairs of materials making it possible to reduce substantially the wear between said friction surfaces relative to any other pair of materials
Implementation Method 3
the joint surface is that of an element made of ceramic which is sintered or deposited on a substrate, or a ceramic-metal composite which is sintered or deposited on a substrate
Implementation Method 4
the joint surface is that of an element made of ceramic which is sintered or deposited on a substrate
Implementation Method 5
one joint surface is that of a substrate covered with amorphous carbon
Data Source
AI summary
Said strap with articulated links, in particular for a watch, comprises at least three adjacent rows of links offset from one adjacent row to another, in which at least one friction surface (3, 13, 23-163) of each joint is made of a material of which the hardness is >800 HV. Said bearing surface (3, 13, 23-163) is in contact with at least one joint element (5, 15, 25-165) having at least one friction surface made of a second material selected from the following materials: ceramic, ceramic-metal composite, amorphous carbon, stainless steel without nickel, cobalt alloy, gold or gold alloy, platinum or platinum alloy, platinoid or platinoid alloy, titanium or titanium alloy, capable of reducing the frictional wear with the friction surface (3, 13, 23-163).