Horological Balance Spring Mechanical Attachment Assembly
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Solution Overview
Problem
Existing methods for attaching balance springs in horological movements face challenges such as mechanical stress, adhesive detachment, and temperature-induced stiffness changes, which affect the precision and consistency of the timepiece's rate.
Innovation Solution
A mechanical assembly that allows for the detachable and stress-free attachment of a balance spring without adhesive, using a retaining means and a locking part to securely engage the outer last coil of the balance spring, enabling easy repositioning and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive is used to attach the balance spring to the stud, then the balance spring can be securely fixed, but the adhesive may detach over time and induce mechanical stress affecting rate precision
Solution Approach 1:
The patent extracts and eliminates the adhesive from the attachment system, replacing it with a purely mechanical attachment mechanism where the balance spring coil is directly engaged with the stud through a collet assembly, avoiding the harmful effects of adhesive detachment and stress
Solution Approach 2:
The patent replaces the chemical bonding system (adhesive) with a mechanical bonding system (collet and stud engagement), where the collet compresses the balance spring coil onto the stud to create a secure mechanical attachment without adhesive
2Reliability
If the balance spring is tightly attached to maintain position, then attachment security is improved, but mechanical stress increases affecting the balance spring's natural oscillation
Solution Approach 1:
The patent applies local quality by creating a localized compression zone within the collet where only the specific attachment point of the balance spring coil is compressed, while the rest of the balance spring remains stress-free and can oscillate naturally
Solution Approach 2:
The collet assembly is designed with inherent compliance and cushioning characteristics that absorb attachment forces before they can transmit stress to the balance spring coil, protecting the oscillating system from mechanical stress
3Ease of manufacture
If adhesive is used to fix the balance spring, then attachment is simplified, but adjustment and repositioning become difficult
Solution Approach 1:
The patent creates a dynamic attachment system where the collet can be moved between a closed position that secures the balance spring coil to the stud and an open position that releases it for adjustment, allowing the attachment to transition between secured and adjustable states
Solution Approach 2:
The patent segments the attachment system into separate functional components (collet, stud, balance spring coil) that can be independently manipulated, allowing the balance spring to be attached or detached by moving the collet without affecting other parts of the movement
Data Source
AI summary
An assembly for the removable attachment of a balance spring of a horological movement including a balance bridge, the assembly including the balance spring, a means of retaining the balance spring, and a removable locking part. The balance spring includes a coil winding which extends between a first free end of an inner first coil and a second free end of an outer last coil, the second free end including an attachment means in which the retaining means is engaged to ensure the removable attachment of the balance spring by its outer last coil. The attachment means is dimensioned so that, in a rest position, the balance spring is not in contact with the retaining means engaged in this attachment means, the locking part for the removable attachment of the second free end being engaged on the retaining means to lock the attachment means.