Composite Timepiece Balance Wheel with Three-Point Mass Positioning
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Solution Overview
Problem
Existing methods for manufacturing composite balance wheels for timepieces face challenges in achieving precise positioning of inertial masses, which affects the moment of inertia and chronometric precision, while avoiding the high cost and complexity of galvanic growth techniques.
Innovation Solution
A balance wheel design featuring a low-density structure with housings for inertial masses made of a denser material, where the masses are precisely positioned using point contact and adhesive or brazing, ensuring minimal unbalance and optimal moment of inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If galvanic growth technique is used to form inertial masses, then positioning precision is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent replaces the complex galvanic growth process with a mechanical assembly approach. Pre-fabricated inertial masses are positioned using mechanical features (protrusions fitting into recesses, adjustment screws, or magnetic alignment) and then fixed with adhesive or welding. This substitution eliminates the need for electrochemical deposition while achieving comparable positioning precision through mechanical tolerances and adjustment mechanisms.
Solution Approach 2:
The inertial masses are pre-fabricated with precise geometries and positioning features before assembly. The housing structures are also pre-prepared with matching recesses, alignment features, and bonding surfaces. This preliminary preparation allows for precise positioning during assembly without requiring complex in-situ formation processes like galvanic growth, thereby reducing manufacturing complexity while maintaining precision.
2Ease of manufacture
If simpler joining techniques such as gluing or welding are used, then ease of manufacture is improved, but positioning precision deteriorates
Solution Approach 1:
The assembly process is segmented into distinct stages: positioning the inertial mass using mechanical features (protrusions, recesses, or adjustment mechanisms), applying adhesive or welding, and then curing or cooling. This segmentation allows each stage to be optimized independently - mechanical features ensure precise positioning, while simpler joining methods provide ease of manufacture. The separation of positioning and joining functions resolves the contradiction between precision and ease of manufacture.
Solution Approach 2:
The patent introduces intermediary mechanical features such as protrusions fitting into recesses, adjustment screws, or magnetic alignment elements that mediate between the inertial mass and the housing. These intermediaries provide precise positioning during assembly and can be easily adjusted or replaced, thereby maintaining positioning precision while enabling the use of simpler joining techniques like adhesive bonding or welding instead of complex galvanic growth.
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 solution provides precise manufacturing of composite balance wheels with improved chronometric precision and reduced manufacturing complexity, maintaining high positioning accuracy without the need for galvanic growth.
Implementation Method 1
The inertial masses 3 are rigidly fixed in the peripheral part of the structure 2... The inertial masses 3 are glued into the housings 6
Implementation Method 2
The balance wheel is the oscillating inertial element of a regulating organ... An important characteristic of balance wheels is their moment of inertia to mass ratio
Data Source
Figure 1~2
AI summary
The balance wheel for a timepiece according to the invention comprises a structure (2) made of a first material and inertial masses (3) glued or brazed in respective housings (6) of the structure (2) and made of a second material, the second material being denser than the first material. Each inertial mass (3) is in point contact with the wall of the corresponding housing (6) at three points (B, C, D).