Monolithic Metallic Glass Watch Spring Shaping
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Solution Overview
Problem
Existing methods for manufacturing watch springs using amorphous metal alloys face challenges such as delamination, poor resin properties, and difficulties in achieving the required mechanical properties due to differences between crystalline and amorphous metallic alloys, leading to fragile and unreliable springs.
Innovation Solution
A process involving hyperquenching to produce monolithic metallic glass ribbons with specific thickness and ductility, followed by plastic deformation and controlled heat treatment to achieve desired curvature and mechanical properties, allowing for the creation of functional and reliable watch springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous metal laminate is used for watch springs, then the spring can be manufactured, but delamination occurs during shaping and repeated winding/unwinding
Solution Approach 1:
The patent removes the epoxy resin binder from the laminate structure, extracting the problematic component that causes delamination. The solution uses a monolithic metallic glass ribbon without any resin binding, thereby eliminating the delamination issue while maintaining manufacturability through alternative shaping methods.
Solution Approach 2:
The patent transitions from a composite laminate structure (metallic glass layers bound by epoxy resin) to a monolithic metallic glass material. This eliminates the interface between layers where delamination occurs, while the amorphous structure provides superior elastic properties for spring application.
2Quantity of substance
If thick metallic glass ribbons are produced by rapid quenching, then the spring can be manufactured, but the process cannot produce ribbons up to thirty microns thickness
Solution Approach 1:
The patent changes the cooling rate parameter from extremely rapid quenching (>10^6 K/s) to moderate cooling rates (10-1000 K/s), enabling the production of thick metallic glass ribbons (30-200 microns) that would be impossible with conventional rapid quenching methods while maintaining the amorphous structure.
Solution Approach 2:
The patent utilizes controlled phase transition from liquid to amorphous solid state by adjusting cooling rates. By using moderate cooling rates instead of extreme quenching, the process achieves thick ribbon formation while preventing crystallization and maintaining the desired amorphous metallic glass structure.
3Shape
If plastic deformation is applied to metallic glass at room temperature, then the spring can be shaped, but the material is fragile and catastrophic shear failure occurs
Solution Approach 1:
The patent changes the temperature parameter from room temperature to elevated temperatures (0.5-0.8 Tg), transforming the material behavior from brittle to ductile. This enables plastic deformation and shaping operations while maintaining material integrity, avoiding catastrophic shear failure.
Solution Approach 2:
The patent utilizes the glass transition phenomenon by heating the metallic glass above its glass transition temperature (Tg). In this softened state, the material exhibits ductile behavior allowing plastic deformation. Subsequent cooling below Tg freezes the deformed shape while maintaining the amorphous structure and mechanical properties.
4Strength
If casting is used to shape high mechanical performance alloy, then the spring can be manufactured, but the ribbons are fragile in bending
Solution Approach 1:
The patent changes the temperature parameter during shaping operations, performing plastic deformation at elevated temperatures (0.5-0.8 Tg) where the material is ductile, then cooling to room temperature to achieve the final spring shape. This sequence maintains both high elastic limit and bending ductility.
Solution Approach 2:
The patent performs preliminary plastic deformation at elevated temperatures before final cooling and service use. This preliminary shaping action is performed when the material is ductile and forgiving, allowing complex spring geometries to be formed. The subsequent cooling freezes the shape while the material retains its high strength 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
Enables the industrial-scale production of high-performance watch springs with enhanced mechanical properties and reliability, maintaining ductility and preventing premature failure, while avoiding crystallization and embrittlement.
Implementation Method 1
cooling a liquid metal alloy at a speed greater than 500°C/s in order to obtain a monolithic amorphous metallic glass
Implementation Method 2
cooling a liquid metal alloy at a speed greater than 500°C/s in order to obtain a monolithic amorphous metallic glass
Implementation Method 3
subjecting the whole to a heat treatment to freeze the ribbon in its wound position
Implementation Method 4
heat treatment to freeze the ribbon in its wound position
Data Source
Figure 1
Figure 2a~3b
Figure 4a~5b
AI summary
The invention relates to a method for making a spring for a timepiece that comprises at least one monobloc ribbon of metal glass including at least one curvature. The method is characterized in that said method comprises the step of shaping by means of plastic-deformation said monobloc ribbon in order to obtain at least a portion of said curvature.