Balance Spring Geometry Tuning for Tolerance-Robust Timekeeping
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Solution Overview
Problem
Existing watch balance springs are sensitive to variations and defects in other movement components, power reserve, and mainspring winding, leading to inconsistent oscillation amplitudes and performance deviations.
Innovation Solution
A method for manufacturing balance springs with a numerical model that identifies optimal geometry to minimize sensitivity to these variations, using adjustment variables to compensate for manufacturing and assembly tolerances, ensuring consistent oscillation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional balance springs are used, then manufacturing is simple, but oscillation amplitude varies significantly due to manufacturing and assembly tolerances in other movement components
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-compensating for the effects of manufacturing and assembly tolerances during the balance spring design phase. A numerical model is used to simulate various tolerance scenarios and determine geometry parameters that will compensate for expected variations in other movement components, thereby reducing oscillation amplitude variability before the actual assembly occurs.
Solution Approach 2:
The patent employs parameter changes by modifying the geometry parameters of the balance spring (such as coil spacing, wire diameter, or active coil count) based on the numerical model optimization. These parameter adjustments are specifically designed to counteract the sensitivity to tolerances in other movement components, transforming the balance spring into a less sensitive component without changing its fundamental function.
2Manufacturing precision
If balance spring geometry is optimized to reduce sensitivity to tolerances, then performance consistency improves, but design and manufacturing complexity increases
Solution Approach 1:
The patent uses copying by creating a virtual numerical model that replicates the physical balance spring and its interaction with other movement components. This digital twin allows for extensive simulation and optimization of geometry parameters to reduce tolerance sensitivity, while the actual manufacturing process remains relatively simple. The complex optimization work is performed in the virtual model rather than through iterative physical prototyping.
Data Source
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AI summary
The invention relates to a method for manufacturing watch balance springs (10) for an oscillator of a movement of a timepiece, the oscillator being characterized by oscillations exhibiting variability under the effect of an escapement and/or a gear train and/or a mainspring of the movement of the timepiece, the manufacturing method comprising the following steps: - (100) defining a numerical model representative of a balance spring (10) that one wishes to obtain, said model comprising a plurality of adjustment variables, - (200) defining at least one performance indicator, representative of a desired behavior for the balance spring (10), - (300) identifying at least one optimal value for at least one adjustment variable, the optimal value providing a minimum sensitivity of the performance indicator to the variability of said oscillations of the oscillator,- (400) manufacture at least one spiral (10) with a geometry defined according to said at least one optimal value. The invention also relates to a spiral (10) whose particular geometry provides a minimum sensitivity of the performance indicator to the variability of said oscillations of the oscillator.