Monocrystalline Silicon Timepiece Spring Orientation for Break Resistance
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Solution Overview
Problem
Monocrystalline silicon used in timepiece springs exhibits low mechanical strength, prone to breaking under external stresses without prior plastic deformation, which is critical for maintaining functionality and resisting fatigue.
Innovation Solution
The method involves identifying zones of weakness in the spring and orienting the spring within a monocrystalline material wafer such that the direction of macroscopic stresses in these zones is parallel to the cleavage planes, enhancing the mechanical strength by fabricating the spring with a specific orientation during etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monocrystalline silicon is used for timepiece springs, then corrosion resistance and non-magnetic properties are improved, but mechanical strength deteriorates
Solution Approach 1:
The patent changes the crystallographic orientation parameter of the monocrystalline silicon from conventional orientations to specifically oriented directions (such as <110> or <100> directions) that align with the stress directions in the spring. This parameter change exploits the anisotropic mechanical properties of silicon to achieve higher strength while maintaining the inherent corrosion resistance and non-magnetic characteristics of monocrystalline silicon.
2Weight of moving object
If monocrystalline silicon is used for timepiece springs, then density is reduced, but mechanical strength deteriorates
Solution Approach 1:
The patent modifies the crystallographic orientation parameter of the silicon material to specific directions that exhibit higher strength characteristics. By changing the orientation parameter while maintaining the low density advantage of silicon, the invention achieves both lightweight and high-strength performance in the timepiece spring.
3Strength
If the spring is oriented with stresses parallel to cleavage planes, then mechanical strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent performs preliminary action by pre-orienting the crystallographic axes of the monocrystalline silicon wafer before spring fabrication. The wafer is prepared with specific crystal orientations (such as <110> or <100> directions) that will align with the stress directions in the final spring component. This preliminary orientation preparation simplifies subsequent manufacturing steps and reduces the precision requirements during spring formation, as the favorable crystal orientation is already established.
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 approach significantly increases the mechanical strength of the timepiece springs, demonstrated by a 37% improvement in rupture stress, allowing for reduced dimensions and improved durability.
Implementation Method 1
a timepiece spring made of monocrystalline material, in particular of monocrystalline silicon... which is elastically deformable in a determined plane
Implementation Method 2
it must be able to deform elastically without breaking in order to perform its function and must also be able to resist fatigue
Data Source
AI summary
Disclosed is a method of making a timepiece spring from monocrystalline material including the following steps: drawing the spring; identifying one or more zones of weakness of the spring in which or in at least one of which the spring will break in the event of excessive deformation; manufacturing the spring from a wafer of monocrystalline material extending in a determined plane, while orienting the spring in the wafer such that the direction of the macroscopic stresses in the or each zone of weakness when the spring is deformed is substantially parallel to a plane of cleavage of the material intersecting the determined plane. Also disclosed is a timepiece spring obtained by such a method.