Anodized Light-Metal Pivot Axis for Non-Magnetic Watch Movements
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Solution Overview
Problem
Existing watch pivot materials, such as martensitic carbon steels, are magnetic and prone to corrosion, affecting watch performance and chronometry, while non-magnetic alternatives like austenitic stainless steels lack sufficient hardness and are difficult to machine.
Innovation Solution
A non-magnetic pivot axis made of light metals like aluminum or titanium alloys, coated with an anodic oxide layer, providing high hardness and resistance to wear and shocks, achieved through anodization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If martensitic carbon steels are used for pivot shafts, then high hardness and shock resistance are achieved, but magnetic interference and corrosion sensitivity occur
Solution Approach 1:
The patent changes the material parameter from magnetic martensitic steel to non-magnetic light metal (aluminum or titanium alloy), fundamentally altering the magnetic properties while maintaining mechanical performance through anodization hardening
Solution Approach 2:
The patent creates a composite structure combining light metal base material with hard anodized oxide layer, achieving both non-magnetic properties and high hardness/shock resistance through the synergistic combination of materials
2Object-affected harmful factors
If austenitic stainless steels are used to avoid magnetic interference, then non-magnetic properties are achieved, but insufficient hardness and shock resistance result
Solution Approach 1:
The patent changes the surface hardness parameter of light metal through anodization process, achieving hardness levels comparable to or exceeding traditional steel pivot shafts while maintaining non-magnetic properties
Solution Approach 2:
The patent applies anodization hardening specifically to the surface layer of the pivot shaft, creating a locally hardened outer layer that provides shock resistance while the core material maintains its non-magnetic light metal properties
3Object-affected harmful factors
If austenitic stainless steels are used for pivot shafts, then non-magnetic properties are achieved, but difficult machining and high cost occur
Solution Approach 1:
The patent uses inexpensive light metal materials (aluminum or titanium alloys) that are easier and cheaper to machine compared to austenitic stainless steels, with the added benefit of non-magnetic properties
Solution Approach 2:
The patent changes the material selection parameter from expensive austenitic stainless steel to cost-effective light metals, achieving both ease of manufacture and non-magnetic properties
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 solution offers a non-magnetic pivot axis with high hardness, low inertia, and improved resistance to corrosion and fatigue, ensuring reliable watch operation without magnetic interference.
Implementation Method 1
at least the external surface of said pivot (3) is covered with an anodic layer of oxide of said material (5), obtained by anodization growth
Data Source
Figure 1~2
AI summary
The invention relates to a pivot axis for a watch movement comprising at least one pivot (3) made of a non-magnetic metallic material (4) at at least one end to limit its sensitivity to magnetic fields. Said non-magnetic metallic material (4) is a non-magnetic light metal or a non-magnetic alloy of said light metal, and at least the external surface of said pivot (3) is coated with an anodic layer of oxide of said material (5), obtained by anodizing. The invention relates to the field of watch movements.