Non-magnetic Composite Pivot Axis for Watch Movements
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Solution Overview
Problem
Conventional martensitic carbon steel pivot axes used in mechanical watch movements are magnetic, sensitive to corrosion, and lack sufficient hardness and wear resistance, making them unsuitable for high-performance applications without compromising magnetic sensitivity or corrosion resistance.
Innovation Solution
A non-magnetic pivot axis formed from a composite material with a metallic matrix comprising nickel, titanium, chromium, or other metals loaded with hard particles such as WC, TiC, and TiN, achieving high hardness and wear resistance while minimizing magnetic sensitivity and enhancing corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If martensitic carbon steel is used for pivot axes, then hardness and wear resistance are improved, but magnetic sensitivity and corrosion resistance deteriorate
Solution Approach 1:
The patent applies composite materials by combining a metallic matrix (non-magnetic) with hard particles (carbides, nitrides, oxides) to create a pivot axis material that simultaneously achieves high hardness, wear resistance, and non-magnetic properties. The composite structure allows each component to contribute its advantageous properties.
Solution Approach 2:
The patent changes the material parameters by selecting specific metals with appropriate magnetic properties (non-magnetic or weakly magnetic) and combining them with hard particles in controlled proportions and distributions, thereby achieving the desired balance between hardness and magnetic sensitivity.
2Strength
If martensitic carbon steel is used for pivot axes, then hardness and wear resistance are improved, but corrosion resistance deteriorates
Solution Approach 1:
The composite material structure combines a corrosion-resistant metallic matrix with hard particles, allowing the matrix to provide corrosion protection while the particles provide hardness and wear resistance. This division of functional roles resolves the contradiction between hardness and corrosion resistance.
3Object-affected harmful factors
If austenitic stainless steel is used for pivot axes, then magnetic sensitivity is improved, but hardness and wear resistance deteriorate
Solution Approach 1:
The patent uses composite materials to overcome the limitation of austenitic stainless steel. By embedding hard particles (carbides, nitrides, oxides) in a metallic matrix, the composite achieves both the non-magnetic property of austenitic steel and the high hardness required for pivot axes, resolving the contradiction between magnetic sensitivity and hardness.
4Strength
If hard layers are deposited on pivot axes, then hardness is improved, but reliability deteriorates due to delamination
Solution Approach 1:
The patent merges the hard layer and the substrate into a single composite material structure. The hard particles are integrated within the metallic matrix, creating a unified material rather than a layered structure. This eliminates the interface between layers that causes delamination, while still achieving high hardness through the distributed hard particles.
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 composite material pivot axis achieves high hardness exceeding 1000HV, improved corrosion resistance, and reduced magnetic sensitivity, ensuring reliable operation in watch movements with enhanced toughness and wear resistance.
Implementation Method 1
a composite material having a matrix metallic comprising at least one metal selected from nickel, titanium, chromium, zirconium, silver, gold, platinum, silicon, molybdenum, aluminum or an alloy thereof, said matrix being loaded with hard particles chosen from among WC, TiC, TaC, TiN, TiCN, Al2O3, ZrO2, Cr2O3, SiC, MoSi2, AlN or a combination of these
Implementation Method 2
improved corrosion resistance
Implementation Method 3
in order to limit the sensitivity of the axis to magnetic fields
Data Source
Figure 1~3
AI summary
The pivot pin (1) includes at least one pivot (3) at at least one of the ends of the pivot pin. The pivot is formed of a composite material having a metallic matrix including at least one metal selected from among nickel, titanium, chromium, zirconium, silver, gold, platinum, silicon, molybdenum, aluminum or an alloy of the above metals. The matrix is charged with hard particles selected from among tungsten carbide, titanium carbide, tantalum carbide, titanium nitride, titanium carbonitride, aluminum oxide, zirconium oxide, chromium oxide, silicon carbide, molybdenum silicide, aluminum nitride or their combination, so as to limit the sensitivity of the pin to magnetic fields.