Brazed Titanium-Gold Bi-Metal Watch Component

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Solution Overview

Problem

Watch exterior components made of noble metals like gold or platinum are heavy and costly due to high density, and gold is malleable with average mechanical qualities, necessitating the use of more corrosion-resistant alloys that are sensitive to corrosion and vary in appearance over time.

Innovation Solution

A method involving brazing a titanium or titanium alloy base with gold or platinum alloy cover plates, where the cover plates are at least 0.5 millimeters thick, to create a bi-metallic blank that is then shaped for structural components, using specific solders like Ag-Cu or Pd-Ag-Ga to ensure strong bonding and resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If noble metals like gold or platinum are used for watch exterior components, then excellent corrosion resistance is achieved, but the components become very heavy due to high density

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidweight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent applies composite materials by combining a titanium base metal with a noble metal cover plate (gold or platinum alloy). The titanium base provides lightweight structural support while the thin noble metal cover (minimum 0.5mm thick) provides corrosion resistance and aesthetic appearance. This composite structure resolves the contradiction by achieving the corrosion resistance of noble metals without their high weight penalty.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent segments the watch component into two distinct functional layers: a titanium base structure and a noble metal cover plate. This segmentation allows each material to perform its optimal function - titanium for structural integrity and weight reduction, noble metal for corrosion resistance and appearance - thereby resolving the weight-corrosion resistance contradiction.

Inventive Principle:
Principle #1Segmentation

2Strength

If gold alloys with better mechanical strength are used, then resistance to deformation improves, but corrosion resistance decreases and appearance varies over time

Engineering Contradiction:
Improvemechanical strengthVSAvoidcorrosion resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The composite structure separates the mechanical strength function (handled by the titanium base) from the corrosion resistance function (handled by the noble metal cover). This resolves the contradiction by allowing the use of strong titanium alloy without sacrificing corrosion resistance, as the noble metal layer protects the base metal.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by using different materials with different properties in different locations of the component. The titanium base provides mechanical strength where structural support is needed, while the noble metal cover provides corrosion resistance and aesthetic quality where exposed to environment and wear.

Inventive Principle:
Principle #3Local quality

3Reliability

If solid noble metal components are used, then aesthetic appeal and corrosion resistance are maintained, but manufacturing cost increases significantly

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The composite material approach allows manufacturing cost reduction by replacing expensive solid noble metal with a titanium base and thin noble metal cover. The cost-effective titanium provides structural functionality while using minimal noble metal (at least 0.5mm thick) only where aesthetic and corrosion resistance are required, significantly reducing material costs.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent effectively uses a small amount of expensive noble metal as a protective and aesthetic layer on a cheaper titanium base. This approach replaces the need for expensive solid noble metal components while maintaining the essential functions of corrosion resistance and appearance.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Weight of moving object

If thin noble metal cover plates are used to reduce weight, then weight decreases, but mechanical strength and structural integrity are compromised

Engineering Contradiction:
ImproveweightVSAvoidmechanical strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The composite structure uses the titanium base to provide mechanical strength and structural integrity, allowing the noble metal cover plate to be thin (minimum 0.5mm) without compromising overall strength. The titanium base bears the mechanical loads while the thin noble metal layer provides environmental protection and aesthetics.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The segmentation of functions between the titanium base (structural support) and thin noble metal cover (protection and appearance) enables weight reduction while maintaining mechanical strength. Each layer is optimized for its specific function, resolving the contradiction between thinness and strength.

Inventive Principle:
Principle #1Segmentation

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

This approach results in watch components with excellent mechanical strength, corrosion resistance, and a reduced weight, offering a cost-effective alternative to solid noble metal components while maintaining aesthetic appeal.

Implementation Method 1

A method involves brazing a titanium or titanium alloy base (10) with gold or platinum alloy cover plates (20), where the cover plates are at least 0.5 millimeters thick

Methodology Applied
Scientific EffectBrazing: Brazing

Data Source

PatentEP2852866B1Brazed bi-metal timepiece external component
Publication Date: 2018.07.04 THE SWATCH GRP RES & DEVELONMENT LTD
  • EP2852866B1 patent drawingFigure 1~7
  • EP2852866B1 patent drawingFigure 8~13
  • EP2852866B1 patent drawingFigure 14~20

AI summary

The invention relates to a process for manufacturing a timepiece exterior component (100), characterised in that: a metal base (10) made of a first material comprising titanium or/and a first titanium alloy is provided; a metal covering plate (20) made of a second material is provided, said second material comprising a second metal chosen from gold and platinum or/and a second alloy comprising at least gold or platinum, said covering plate (20) being 0.5 millimetres or more in thickness; said covering plate (20) is brazed to said base (10) with a braze chosen for brazing titanium with gold or platinum, respectively, in order to form a bimetal ebauche (30); and said bimetal ebauche (30) is shaped or/and machined in order to give said structural component (100) its final shape.