Ceramic Watch Case Sealing via Interlocking Undercuts
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Solution Overview
Problem
Existing waterproof watch cases face issues with leak-tight closure due to the elliptical or polygonal shape of the back and complementary groove, leading to rapid wear and sealing problems, and are either complex and costly to produce or limited in shape and color options.
Innovation Solution
A waterproof watch case made from ceramic materials, specifically sintered zirconia, with a design featuring circular arc sections and a broken profile to ensure proper clamping force and mechanical resistance, allowing for progressive tightening and improved sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel is used for the back and middle part, then mechanical resistance and ductility are improved, but design freedom in shape and color is limited
Solution Approach 1:
The patent uses ceramic material (specifically sintered zirconia with hardness ≥1000 HV) instead of traditional steel to create a composite material solution that provides both high mechanical resistance and enhanced design freedom. The ceramic material offers hardness exceeding 1000 HV while enabling greater versatility in shapes and colors compared to steel.
2Adaptability or versatility
If ceramic material is used for the back and middle part, then design freedom in shape and color is improved, but ductility and deformation capability are reduced
Solution Approach 1:
The patent changes the material parameter from metallic (steel) to ceramic (sintered zirconia), accepting the trade-off of reduced ductility in exchange for significantly enhanced design freedom. The ceramic material's properties are optimized through sintering processes to achieve the required mechanical strength despite lower ductility.
3Duration of action of stationary object
If the back is made of hard ceramic material, then wear resistance is improved, but the ability to deform for proper surface contact is reduced
Solution Approach 1:
The patent incorporates preliminary deformation features directly into the ceramic back component during manufacturing. The broken profile design with circular arc sections is pre-formed to compensate for the ceramic material's inability to deform later, ensuring proper surface contact and clamping force without requiring post-manufacturing deformation.
4Reliability
If elliptical or polygonal groove shape is used, then initial sealing is achieved, but rapid wear and sealing failure occur after cycles
Solution Approach 1:
The patent replaces the elliptical or polygonal groove shape with a circular groove having a constant radius. This curved geometry distributes contact forces more uniformly around the entire circumference, preventing stress concentration at specific points and thereby significantly improving sealing durability over multiple opening and closing cycles.
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 ceramic watch case provides reliable sealing, reduced wear, and greater design freedom in shape and color, overcoming the limitations of traditional materials while maintaining excellent clamping force and mechanical resistance.
Implementation Method 1
the back and the middle are made of sintered zirconia
Implementation Method 2
A seal carried by one of these elements is pressed axially against a shoulder of the other
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Sealed watch case comprising two elements respectively forming a case body (2) and a bottom (4), a seal (10) being interposed between said two elements, a first of said elements comprising a first portion of peripheral side wall (20) with an undercut which extends vertically, the second element also having a second portion of peripheral side wall (26) with an undercut which extends vertically and which has a shape complementary to the first portion of peripheral side wall (20) of the first element, the first and second portions of peripheral side wall (20, 26) of the first and second elements being arranged such that, in a first angular position with respect to a pivot axis referred to as the "closure axis" (0-0'), the first element can be dissociated from the second element and such that, in a second angular position in which the first element is turned through a predetermined angle (Q) around said closure axis (0-0') starting from the first position, the first element is blocked in the second element by compressing the seal (10). The bottom (4) and the case body (2) are produced from a material having a hardness of at least 1000 HV. The bottom comprises an annular peripheral shoulder (8) which receives a seal (10) arranged in order to be compressed between a first support surface (12) of the annular peripheral shoulder (8) and an internal face (14) of the case body (2).