Watch Case-Back Bayonet Attachment for Watertight Angular Locking
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Solution Overview
Problem
Existing watch assemblies face challenges in achieving watertight and secure connections with angular indexing while preventing involuntary disassembly, which often require after-sales intervention for maintenance.
Innovation Solution
A fixing device for a watch back cover that uses a pin and groove system with elastic deformation, providing angular indexing and bayonet fitting to ensure secure and watertight assembly, requiring a special tool for disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bayonet connection is used to assemble watch parts, then the assembly becomes secure and watertight, but the device complexity increases
Solution Approach 1:
The bayonet connection system is segmented into distinct functional elements: the middle with pin recesses, the back cover with protruding pins, and the seal. This segmentation allows each component to perform its specific function (mechanical connection, angular indexing, sealing) while maintaining overall simplicity and reliability of the assembly
Solution Approach 2:
The pin protrusions on the back cover are designed to fit into recesses on the middle, creating a nested configuration where the back cover's pins engage with the middle's pin recesses. This nested structure provides secure mechanical connection and angular indexing in a compact arrangement
2Manufacturing precision
If angular indexing is implemented for component alignment, then the positioning precision improves, but the ease of operation deteriorates due to difficulty in achieving proper alignment and tightening
Solution Approach 1:
The bayonet connection system is designed to be self-indexing: when the back cover is rotated during assembly, the pins automatically engage with the pin recesses at the correct angular position, and the seal compression provides self-locking. This eliminates the need for complex alignment procedures or specialized tools, making the operation simple while maintaining precise angular indexing
Solution Approach 2:
The connection system transitions from a static alignment problem to a dynamic assembly process: the back cover is rotated dynamically during assembly, allowing the pins to naturally find and engage with the pin recesses at the correct angular position, while the seal provides progressive self-locking as compression increases
3Reliability
If the back cover is made secure against disassembly, then the reliability improves, but the ease of repair deteriorates as disassembly requires special tools
Solution Approach 1:
The bayonet connection system incorporates preliminary anti-action through the seal compression and pin engagement geometry: the seal is pre-compressed to create friction resistance, and the pins are positioned to engage with the pin recesses in a way that requires significant rotational force to disengage. This preliminary anti-action prevents accidental disassembly while allowing intentional disassembly by qualified personnel using appropriate tools
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
Ensures watertight and secure assembly with angular indexing, preventing accidental disassembly and maintaining sealing integrity, while allowing easy maintenance by qualified personnel.
Implementation Method 1
a pin (4) secured to the middle (1), the pin (4) comprising at least one elastically deformable zone
Data Source
Figure 1~2b
Figure 3a~4b
Figure 5a~5b
AI summary
A device for attaching a case back to a watch case, the case back having a shoulder forming a cover arranged to fully or partially cover the case and a body arranged to rest within the case, said device comprising at least one pin integral with the case, and a gasket mounted between the case back and the case. According to the invention, the case back comprises, near its periphery, at least one groove, the pin being arranged to slide in the groove between a first position, called the insertion position in which the case back is free, and a second position, called the locking position, in which the case back is locked and positioned angularly relative to the case, and said groove comprising at least one bump to form a resistance point and increase the torque when the pin passes over the bump.