Watch Bearing Stone Laser Ablation for Straight Cuts and Fine Finish
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Solution Overview
Problem
Conventional machining techniques for ruby and sapphire stones in watch components are imprecise, unable to create complex shapes and functionalize surfaces beyond simple holes or rough indentations, leading to inconsistent material ablation and thermal damage.
Innovation Solution
A method using ultra-short pulsed lasers with a precession system to focus the beam and cancel the cone angle, allowing precise material removal layer by layer, achieving surface finishes of Ra 0.1 µm and enabling complex shapes like straight cuts and functionalized surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional machining techniques are used to shape ruby and sapphire stones, then the manufacturing process is simple, but the manufacturing precision and ability to create complex shapes is insufficient
Solution Approach 1:
The patent replaces conventional mechanical machining techniques with laser ablation technology. The laser beam removes material through photothermal vaporization rather than mechanical contact, enabling precise creation of complex shapes, through-holes, and surface features that are impossible or impractical to achieve with traditional cutting tools while maintaining manufacturing feasibility
Solution Approach 2:
The patent utilizes controllable laser parameters including pulse duration (nanosecond to femtosecond range), wavelength, and power density to achieve precise material removal. By adjusting these parameters, the system can create different shapes, control heat-affected zones, and achieve desired surface finishes, thereby resolving the contradiction between precision and process complexity
2Manufacturing precision
If conventional laser drilling is used to create holes in stones, then the process is straightforward, but the manufacturing precision and consistency of hole dimensions is insufficient
Solution Approach 1:
The patent employs pulsed laser radiation with specific pulse durations (nanosecond to femtosecond) to remove material in controlled increments. This periodic action allows precise control over hole depth and diameter, ensures consistent dimensions through repeated pulses, and prevents thermal accumulation that would compromise hole quality, thereby achieving high precision while maintaining manufacturing ease
Solution Approach 2:
The patent replaces mechanical drilling with laser ablation, eliminating the need for physical contact between drill bits and the stone. This substitution enables consistent hole dimensions through optical field control rather than mechanical tool wear, achieving superior precision while simplifying the manufacturing process
3Productivity
If focused laser beam is used to remove material, then material ablation efficiency is improved, but the cone angle of the beam causes inconsistent ablation and prevents straight cuts
Solution Approach 1:
The patent introduces an asymmetric correction mechanism by tilting the laser beam or using a moving lens system that compensates for the inherent cone angle. This asymmetric adjustment ensures uniform beam diameter across the work area, enabling straight cuts and consistent ablation depth while preserving the high material removal efficiency of focused laser beams
Solution Approach 2:
The patent employs dynamic adjustment of the laser focusing system, including movable lenses and adjustable beam angles, to compensate for the cone effect in real-time. This dynamic correction maintains optimal beam focus and uniform diameter across different positions, achieving both high productivity and manufacturing precision for straight cuts
4Speed
If continuous laser beam is used for material removal, then processing speed is high, but thermal heating damages the stone quality
Solution Approach 1:
The patent uses pulsed laser radiation with pulse durations in the nanosecond to femtosecond range, delivering energy in short bursts rather than continuous exposure. This periodic action allows rapid material removal at high processing speeds while providing cooling intervals between pulses that prevent thermal accumulation and damage to the stone, thereby maintaining both speed and reliability
Solution Approach 2:
The patent employs ultra-short pulse durations (nanosecond to femtosecond) that deliver energy so quickly that material vaporizes before heat can diffuse to surrounding areas. This 'rushing through' approach achieves high processing speed while minimizing thermal-affected zones, preserving stone quality and preventing thermal damage
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 creation of precise stone shapes and surfaces with reduced thermal impact, achieving Ra 0.025 µm finishes, suitable for watch components with improved friction reduction and functional integration.
Implementation Method 1
the ablation is carried out by scanning at least one face of the body with ultrashort pulsed laser radiation of less than one hundred picoseconds
Implementation Method 2
it is possible to remove material from stone with extreme precision
Data Source
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AI summary
The invention relates to a method for manufacturing a stone (30), in particular for a timepiece, from a mineral body that is monocrystalline or polycrystalline in nature. The method comprises a step of ablation, in which the body is subjected to material ablation carried out by scanning at least one face of the body using ultra-short pulse laser radiation, the duration of which is less than 100 picoseconds and the beam of which is guided by a precession system having at least three axes and which is configured to at least partially eliminate the angle of the laser cone, which results from the focusing of the laser. The invention further relates to a mineral stone (30) that is monocrystalline or polycrystalline in nature, in particular for a timepiece movement, wherein the stone (30) is obtainable by the method. The stone particularly comprises a face (25) which is provided with a peripheral rim (27), in particular for laterally surrounding an endstone (35) in a bearing.