Sprung Balance Oscillator Torque Sorting and Cutting

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Solution Overview

Problem

Existing methods for manufacturing oscillators with balance springs and balances in the watchmaking industry are costly and lack precision, especially when dealing with large torque variations in balance springs, which complicates adjustments and affects chronometric performance.

Innovation Solution

A method involving measuring the average moment of inertia of a batch of balances, providing balance springs with an excess number of coils, making initial cuts to measure and sort torque, assembling to achieve intermediate frequency, and making final cuts to achieve precise oscillation frequency and attachment point angle within a tolerance of +/−50°.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the Omegametric system is used to classify and pair balance springs and balances, then frequency precision is improved, but manufacturing cost and logistical complexity increase significantly

Engineering Contradiction:

Improvefrequency precisionVSAvoidlogistical complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-classifying balance springs into torque categories (low, medium, high) during manufacturing, and pre-determining the number of coils to remove based on the balance inertia category. This preliminary classification and preparation eliminates the need for complex real-time matching and extensive component stocks, thereby reducing logistical complexity while maintaining frequency precision.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the Spiromatic system is used to cut balance springs to length, then manufacturing cost is reduced, but attachment point precision deteriorates to +/−50° tolerance

Engineering Contradiction:

Improvemanufacturing costVSAvoidattachment point precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies local quality by differentiating the precision requirements for different parts of the balance spring. The attachment point region requires high precision (+/−50° tolerance) while other portions can be manufactured with standard tolerances. The method achieves this by making a first cut to establish the attachment point at the correct angle, then making a second cut to adjust the length, thereby ensuring local precision where needed while maintaining cost-effectiveness.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If balance springs with large torque variation are used, then component versatility is improved, but assembly difficulty and chronometric performance deteriorate

Engineering Contradiction:

Improvetorque variation rangeVSAvoidassembly difficulty

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent applies parameter changes by systematically varying the number of coils removed from the balance spring based on the measured torque value and balance inertia category. By changing the coil count parameter (from 1 to 3 coils removed), the method adapts to large torque variations in balance springs, making assembly feasible while maintaining chronometric performance. This parameter-based adaptation simplifies the assembly process despite wide torque dispersion.

Inventive Principle:

Principle #35Parameter changes

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

This method allows for cost-effective assembly of oscillators with high reliability and accuracy, effectively addressing the challenges of torque dispersion and precision in existing techniques.

Implementation Method 1

sprung balance assemblies... balance spring... torque... oscillation frequency

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

measuring the average moment of inertia of a batch of balances... inertia adjustment... oscillation frequency

Methodology Applied

Scientific EffectMoment of inertia: Moment of Inertia

Data Source

PatentUS20250164930A1Method for manufacturing a sprung balance oscillator for high torque variation balance springs

Publication Date: 2025.05.22 NIVAROX FAR SA

AI summary

A method for manufacturing an oscillator for a timepiece made from a balance and a balance spring, the method including measuring the average moment of inertia of a batch of balances; providing pinned up balance springs, the balance springs having an excess number of coils forming up to three more turns than the final number of coils; making a first predetermined external cut of the balance springs over a length of one to two coils, then measuring the torque of the balance springs and sorting them according to the value of the measured torque; assembling the balance springs, whose measured torque corresponds to the balances, are assembled to form an oscillator with an intermediate frequency and to determine the length to be cut to achieve the desired oscillation frequency; making a second external cut of the balance springs selected to achieve both the desired oscillation frequency and a target value.