Watch Movement Clamp With Variable Stiffness
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Solution Overview
Problem
Existing systems for fixing timepiece movements to watch cases are prone to plastic deformation and loss of contact during assembly and impact, leading to reliability and robustness issues.
Innovation Solution
A system utilizing at least one clamp made of a superelastic alloy, such as Nitinol, with a variable bending stiffness, where the bent length and bearing points are modified to distribute stress and prevent plastic deformation, using inclined surfaces and varying cross-sections to maintain contact and restore force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clamp is used to fix the movement to the case, then the movement is held in position, but the clamp is prone to plastic deformation under impact
Solution Approach 1:
The clamp's stiffness parameter is changed by modifying its geometric configuration. The clamp features a variable cross-section with different thicknesses along its length, creating zones of different stiffness. The thinnest portion is positioned at the bending point to optimize elastic deformation characteristics while preventing plastic deformation under impact loads.
Solution Approach 2:
The clamp is designed to dynamically adapt its stiffness during operation. During normal wear, the clamp maintains a fixed configuration. During impact, the clamp elastically deforms to absorb shock energy, then returns to its original position. The dynamic behavior allows the clamp to be flexible during assembly and rigid during impact resistance.
2Strength
If the clamp stiffness is increased to prevent deformation, then impact resistance improves, but the clamp cannot accommodate assembly tolerances
Solution Approach 1:
Different portions of the clamp are given different local qualities in terms of stiffness. The clamp has a variable cross-section where the thinnest portion is located at the bending point to allow controlled elastic deformation for tolerance accommodation, while other portions maintain sufficient thickness for overall structural strength and impact resistance.
Solution Approach 2:
The clamp is segmented into zones with different thicknesses and stiffness characteristics. The variable cross-section creates distinct functional zones: a flexible zone at the bending point for tolerance accommodation, and stiffer zones at the ends for structural support and force transmission to the movement and case.
3Strength
If the clamp is made thinner to reduce stress concentration, then plastic deformation risk decreases, but the clamp strength is reduced
Solution Approach 1:
The clamp's cross-sectional parameter (thickness) is changed along its length rather than being uniform. The thinnest portion is strategically positioned at the bending point where stress concentration occurs during assembly, reducing plastic deformation risk. The thicker portions at the ends maintain sufficient bearing capacity for holding the movement and transmitting forces to the case.
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
The system provides a robust and reliable fixing mechanism that prevents plastic deformation and maintains contact between the movement and the case, even under impact, by modulating stiffness and distributing stress effectively.
Implementation Method 1
at least one clamp (1), in particular at least two clamps (1), preferably three clamps (1) or four clamps (1), which is intended to come into contact firstly with the movement (2) and secondly with the watch case element (3)
Implementation Method 2
The clamp (1*) is thus elastically deformed when assembling the movement such that the elastic restoring force of the clamp holds a surface (2b*) of the movement (2*) against a surface (3b*) of the middle (3*)
Data Source
AI summary
The system (10) for fixing a timepiece movement (2) to a watch case (30) element (3) includes at least one clamp (1), in particular at least two clamps, preferably three clamps or four clamps, which is intended to come into contact firstly with the movement and secondly with the watch case element, and a device (2a′; 3a′) for modifying the stiffness of the at least one clamp, particularly for modifying the bending stiffness of the at least one clamp, when the movement is fixed and/or displaced relative to the watch case element.