Balance Spring Defect Detection via Vibratory Resonance Analysis
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Solution Overview
Problem
The manufacturing of balance springs on a wafer results in significant geometric dispersion in dimensions and stiffness, leading to a high dispersion in resonance frequencies, making it challenging to optimize the manufacturing yield and identify defects such as bonded coils, material porosity, or contamination.
Innovation Solution
A method involving vibratory excitation of balance springs or blanks to identify resonance frequency characteristics, which are then subjected to a prediction machine to determine if defects are present, allowing for the detection of defects without assembly and reducing contamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If balance springs are manufactured on a wafer using microfabrication technologies, then manufacturing efficiency and precision are improved, but geometric dispersion in dimensions and stiffness increases, leading to high dispersion in resonance frequencies
Solution Approach 1:
The patent applies preliminary classification by performing vibratory tests on balance spring blanks before final assembly. This early detection allows defective blanks to be identified and removed from the production flow before they consume additional assembly resources, thereby resolving the contradiction between high-volume manufacturing and geometric precision control.
Solution Approach 2:
The patent replaces traditional mechanical assembly and testing methods with vibratory excitation and resonance frequency analysis. By using vibratory tests to detect defects such as bonded coils, material porosity, or contamination, the system achieves rapid, non-contact inspection that maintains high productivity while improving detection precision without the geometric dispersion issues of manual assembly methods.
2Reliability
If traditional assembly and testing methods are used, then defect detection is possible, but productivity is reduced and contamination risks increase
Solution Approach 1:
The patent replaces traditional mechanical assembly and testing with vibratory excitation methods. By exciting the balance spring blanks with vibratory forces and analyzing their resonance frequencies, the system can detect defects non-contactly and rapidly, maintaining high reliability in defect detection while significantly improving productivity and eliminating contamination risks associated with manual handling and assembly.
Solution Approach 2:
The patent introduces vibratory excitation as an intermediary between manufacturing and final assembly. This intermediate testing stage uses vibratory signatures to detect defects without requiring physical assembly, serving as a efficient mediator that maintains quality control while streamlining the production flow and avoiding contamination from premature assembly operations.
3Reliability
If balance springs are assembled before testing, then comprehensive functionality can be evaluated, but contamination risks and rework costs increase
Solution Approach 1:
The patent performs vibratory testing on balance spring blanks before they are assembled into complete movements. This preliminary evaluation of vibratory characteristics allows detection of defects such as bonded coils, material porosity, or contamination in the blanks themselves, enabling rejection of defective components before they contaminate the assembly process or require costly rework after assembly.
Solution Approach 2:
The patent extracts the testing function from the final assembly process by testing balance spring blanks in isolation using vibratory excitation. This separation allows comprehensive evaluation of the balance spring's intrinsic properties without requiring complete assembly, thereby eliminating contamination risks associated with handling and assembling multiple components while maintaining reliable defect detection.
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 enables faster and more reliable detection of defective balance springs, improving productivity, quality, and precision by identifying defects before assembly and reducing the need for costly rework.
Implementation Method 1
applying to the balance spring or balance spring blank (200) a vibratory excitation that varies over time
Implementation Method 2
identifying at least one characteristic of a resonance frequency of the balance spring or balance spring blank (200)
Data Source
AI summary
Method for testing a balance spring or a balance spring blank arranged to form a balance spring, the balance spring being required to have at least one predetermined expected resonance frequency, the testing method including the following steps:a. applying to the balance spring or balance spring blank, a vibratory excitation that varies over time in order to cover a predetermined frequency range,b. identifying at least one characteristic of a resonance frequency of the balance spring or balance spring blank, such as a resonance peak, during, or in response to, the vibratory excitation over the predetermined frequency range,c. subjecting the resonance frequency characteristic identified in step b. to a prediction machine in order to determine if the balance spring or balance spring blank is affected by a defect.