Collet-Hairspring Assembly via Soft Intermediate Deformation
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Solution Overview
Problem
The assembly of hard materials like silicon, diamond, or corundum parts on axes in watchmaking is challenging due to their low plastic deformation, which leads to damage from mechanical stresses, and existing methods either require additional parts, increase assembly thickness, or are difficult to control radially.
Innovation Solution
A method using an intermediate soft material part with a hole and a ledge to securely assemble the hard material part on a support pin, where the soft material is deformed thermally to fit into interstices, allowing for axial and angular fixation without radial compression, thus minimizing stress on the hard material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If driving in technique is used to assemble hard material parts on axes, then concentric assembly is achieved, but the hard materials are damaged due to mechanical stresses
Solution Approach 1:
The patent introduces a compliant intermediate element between the support pin and the hard material part. This intermediary component absorbs the mechanical stresses during assembly through its elasticity, preventing damage to the hard material while ensuring proper centering and concentric assembly of the components.
2Strength
If additional parts are used to assemble hard material parts without constraint, then assembly damage is avoided, but assembly thickness increases and axis lengthening is required
Solution Approach 1:
The compliant intermediate element is designed to be integrated within the existing assembly structure, nesting the protective function within the space already available between the support pin and the hard material part. This eliminates the need for additional external parts that would increase overall assembly thickness or require axis lengthening.
3Reliability
If intermediate part deformation is used to assemble hard material parts, then fixation is achieved, but radial stresses are difficult to control and unfavorable for the hard part
Solution Approach 1:
The patent changes the material parameter of the intermediate element to be compliant or elastic rather than rigid. This parameter change allows the intermediate element to deform in a controlled manner during assembly, absorbing radial stresses and preventing unfavorable stress concentrations on the hard material part while still achieving reliable fixation.
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 precise, stress-free assembly of hard material parts on axes with excellent centering and reduced thickness, eliminating the need for additional parts and minimizing radial deformation, enabling reliable and precise mounting of components like hairsprings on support pins.
Implementation Method 1
step iii is done by thermal deformation of the intermediate piece so that it takes place at least partially in the interstices
Data Source
Figure 1~1c
Figure 2~2c
Figure 3~3c
AI summary
The method involves providing an intermediate piece in soft material e.g. collet (12), piercing a hole in the intermediate piece, and mounting the intermediate piece on a support shaft, where the intermediate piece defines a face (18) and an edge (20) around the hole. A piece in hard material e.g. hairspring (10), is pierced by an opening. The piece in hard material is placed on the edge of the intermediate piece. The intermediate piece is deformed in a manner to integrate the pieces axially and angularly to form an assembly. The assembly is mounted on the shaft. An independent claim is also included for a collet-hairspring assembly comprising a flange that is folded over an intermediate piece.