Ceramic Timepiece Case Fitting Surface Wear Control
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Solution Overview
Problem
Ceramic timepiece cases wear out quickly when the lid member is repeatedly attached and detached, leading to compromised waterproof and dustproof properties, which can cause malfunction and allow moisture and dust to infiltrate.
Innovation Solution
A timepiece case with a zirconium oxide-based ceramic fitting surface having specific roughness and texture characteristics, including an arithmetic mean roughness of 0.6 µm or less and a reduced peak height of 0.9 µm or less, which reduces wear and maintains waterproof and dustproof properties over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the timepiece case is formed of ceramics to achieve high quality and aesthetic appearance, then the appearance quality is improved, but the fitting surface wears out quickly when the lid member is repeatedly attached and detached
Solution Approach 1:
The patent applies surface treatment to change the physical parameters of the fitting surface, specifically controlling the arithmetic mean roughness (Ra) to be 0.2 µm or less and the maximum peak height (Rpk) to be 0.5 µm or less. This parameter optimization reduces wear while maintaining the ceramic material's aesthetic appearance and structural integrity.
Solution Approach 2:
The surface treatment is performed in advance during the manufacturing process, before the timepiece is put into service. By pre-treating the fitting surface to achieve the specified roughness parameters, the patent prevents wear issues from developing during repeated lid member attachment and detachment operations.
2Ease of operation
If the fitting surface is worn out due to repeated lid member attachment and detachment, then the ease of operation is maintained, but the waterproof and dustproof properties deteriorate
Solution Approach 1:
By optimizing the surface roughness parameters (Ra ≤ 0.2 µm, Rpk ≤ 0.5 µm), the patent creates a fitting surface that maintains low friction for easy lid member operation while simultaneously preventing wear that would compromise the sealing interface and waterproof/dustproof properties.
3Shape
If conventional ceramic materials are used for the timepiece case, then the aesthetic appearance is achieved, but dust generated from wear penetrates into movements causing malfunction
Solution Approach 1:
The patent reduces wear dust generation by optimizing the surface roughness parameters of the fitting surface (Ra ≤ 0.2 µm, Rpk ≤ 0.5 µm). This minimizes the amount of dust generated from wear during repeated lid member attachment and detachment, preventing dust from penetrating into the movements and causing malfunction, while preserving the aesthetic appearance of the ceramic case.
Data Source
Figure 1
AI summary
A timepiece case according to the present disclosure is formed of ceramics. Further, the timepiece case includes a fitting surface facing a lid member when the lid member is fitted to the timepiece case. An arithmetic mean roughness Ra of the fitting surface which is obtained from a roughness profile, is 0.6 µm or less, and a reduced peak height Rpk of the fitting surface which is obtained from the roughness profile, is 0.9 µm or less.