Polycrystalline Titanium Timepiece Parts Metallic Luster Hardness
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Solution Overview
Problem
Timepiece parts made from titanium or titanium alloys face challenges in achieving a high-grade metallic luster and consistent hardness due to variations in crystal grain size and orientation, which affects their brilliance and durability.
Innovation Solution
A manufacturing method involving a heat treatment process to coarsen crystals, followed by an etching process to mirror-finish the surfaces and align them differently, ensuring a metallic luster while maintaining hardness consistency through careful control of grain size and processing order to prevent dimensional inaccuracies and luster damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If crystal grains are coarsened to several mm or more to obtain sufficient metallic luster, then the metallic luster is improved, but the timepiece part may be formed as a monocrystal causing variation in hardness
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystal grain size within a specific range (0.1 mm to several mm) rather than allowing unlimited coarsening. This parameter optimization enables the crystal surfaces to reflect light brilliantly while maintaining polycrystalline structure for consistent hardness throughout the timepiece part.
Solution Approach 2:
The patent implements partial action by coarsening only certain crystal grains to specific sizes rather than uniformly coarsening all grains to several mm. This selective coarsening creates sufficient light reflection areas for metallic luster while preventing the formation of a single large monocrystal, thus maintaining hardness consistency through retained polycrystalline structure.
2Illumination intensity
If heat treatment is performed after shape processing, then crystal coarsening for metallic luster is achieved, but bending occurs and dimensional accuracy decreases
Solution Approach 1:
The patent applies preliminary action by performing shape processing before heat treatment. The timepiece part is first formed into its final shape with precise dimensions, and then heat treatment is applied to coarsen crystal grains for metallic luster. This sequence prevents dimensional changes during heat treatment while still achieving the desired crystal structure and optical properties.
3Manufacturing precision
If shape processing is performed after etching, then dimensional accuracy is maintained, but the metallic luster provided by etching is damaged
Solution Approach 1:
The patent applies preliminary action by completing shape processing before etching. The timepiece part is first shaped with precise dimensions, then etched to create the metallic luster on the crystal surfaces. By performing etching after shape processing, the brilliant metallic luster is achieved without subsequent mechanical operations that could damage the etched surface finish.
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 method provides a timepiece part with a brilliant metallic luster and reduced hardness variation, ensuring both aesthetic appeal and functional reliability by aligning crystal surfaces differently and controlling grain size within specific limits.
Implementation Method 1
a heat treatment process that heat-treats the polycrystalline material and coarsens a plurality of crystals included in the polycrystalline material
Implementation Method 2
an etching process that etches the polycrystalline material, mirror-finishes the surfaces of each crystal, and makes the normal directions of the surfaces of each crystal to be different from one another
Data Source
AI summary
A timepiece part, such as a balance staff, an oscillating weight or a dial, is made of polycrystalline material having a plurality of crystals each having a size of 0.7 μm or more and 3 mm or less. The crystals at a surface of the timepiece part have mirror-finished surfaces, and the surfaces may be anodized to provide corrosion resistance. The normal directions of the mirror-finished surfaces are different from one another and provide a metallic luster to the timepiece part.