Composite Watch Case with Ceramic Outer and Metallic Inner Frame
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Solution Overview
Problem
Existing watch case designs using hard mineral materials for the outer middle part face challenges in assembly due to mechanical stress and require bonding with metal components, which can lead to adhesion issues and longevity problems, particularly in high-end timepieces.
Innovation Solution
A composite watch case design featuring an outer middle part made of ceramic with a metallic inner caseband assembled without mechanical stress, using a screwing mechanism between two rings to lock the caseband, allowing for minimal machining of the ceramic and avoiding the need for glue, with radial and axial extensions ensuring secure assembly and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bonding is used to assemble the outer caseband made of mineral material and the inner metal caseband, then the assembly is achieved, but adhesion issues and longevity problems occur due to glue aging
Solution Approach 1:
The patent replaces the chemical bonding system (glue) with a mechanical locking system. The outer caseband is locked to the inner caseband through a mechanical interlocking mechanism involving a groove in the inner caseband and a protrusion on the outer caseband, eliminating the need for adhesive bonding and its associated aging problems.
Solution Approach 2:
The caseband is divided into two separate components: an outer caseband made of mineral material and an inner caseband made of metal. This segmentation allows each component to be optimized for its specific material properties while being assembled through a mechanical interface rather than bonding.
2Strength
If the outer middle part is made of hard mineral material, then protection and aesthetics are improved, but mechanical stress during assembly causes difficulties
Solution Approach 1:
The case is segmented into an outer decorative protective layer (mineral material) and an inner structural component (metal). This allows the mineral material to provide protection and aesthetics without bearing mechanical assembly loads, while the metal inner caseband handles all machining and assembly operations.
Solution Approach 2:
The inner metal caseband acts as an intermediary between the mineral outer caseband and the watch movement. It provides the mechanical interface for assembly while the outer caseband remains stress-free, serving only its protective and aesthetic functions.
3Manufacturing precision
If through passages are made in the outer middle with little clearance, then assembly precision is improved, but mechanical stress on the ceramic increases
Solution Approach 1:
The through passages are created in the inner metal caseband rather than the outer mineral caseband. This segmentation allows precise machining of clearance-fit passages in the metal component without subjecting the mineral material to mechanical stress during assembly.
Solution Approach 2:
The inner metal caseband serves as an intermediary that carries the mechanical interface for control device rods. It absorbs all mechanical stresses from the through passages, allowing the outer mineral caseband to have precisely fitted passages without experiencing stress concentration.
Data Source
Figure 1~3
Figure 4
AI summary
The frame includes an inner metallic frame (10) and an outer frame (20) made of a natural or synthetic inorganic material such as ceramic. The inner frame (10) comprises an upper bushing (12) and a lower bushing (14), each bushing comprising a radial peripheral extension (13, 15) with opposite bearings for mechanically blocking the outer frame (20), e.g. by screwing the two bushings (12, 14) into one another.