Laser Engraving Timing for Etched-Look Timepiece Components
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Solution Overview
Problem
Conventional laser machining of watch components often results in engravings with imperfect straight junctions due to high-frequency pulse overlap, leading to hollows at the periphery and end of the engraving, which are not suitable for high-end watch components that require a more artisanal appearance.
Innovation Solution
Programming the laser source to emit the first pulse after the beam has moved from the starting point and the last pulse before reaching the end point, allowing for a time shift and varying longitudinal coverage rates, resulting in a curved junction between the sides and bottom of the engraving, similar to chemical etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser source is programmed to emit pulses at high frequency along the entire vector path including start and end points, then the engraving process is efficient and complete, but hollows and grooves form at the periphery due to pulse overlap
Solution Approach 1:
The laser beam is moved to the starting point and the first pulse is emitted after a time lag before the beam begins its movement along the path. This preliminary positioning and delayed pulse emission prevent excessive pulse overlap at the beginning of the vector, eliminating hollows at the periphery while maintaining engraving efficiency
Solution Approach 2:
The laser source is programmed to emit the last pulse before the beam reaches the ending point, with a time lag that prevents the beam from continuing to move after pulse emission stops. This preliminary cessation of pulses before reaching the end point eliminates grooves at the periphery while maintaining complete engraving coverage
2Productivity
If the laser pulses are emitted simultaneously with the beam movement, then the engraving is completed efficiently, but the junction between edges and base becomes straight and imperfect
Solution Approach 1:
Time lags are introduced at the beginning and end of the laser vector path, changing the temporal parameters of pulse emission relative to beam movement. This creates a variable pulse distribution along the path that produces a curved junction profile similar to chemical etching, while maintaining the efficiency of laser machining
Solution Approach 2:
Different temporal characteristics are applied to different portions of the engraving path: time lags are applied specifically at the start and end points, while the middle portion maintains normal pulse emission timing. This local differentiation creates the desired curved junction profile at critical areas without compromising overall engraving efficiency
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 method produces engravings with precise control and high reproducibility, achieving an appearance similar to chemical etching with improved quality and resolution, suitable for high-end watch components.
Implementation Method 1
a laser source (4) arranged to emit pulses of duration equal to or less than a picosecond and define a movable incident laser beam (6) relative to the substrate (2), and perform an engraving on the latter
Data Source
Figure 1a~1c
Figure 2~3a
Figure 3b
AI summary
The invention relates to a method for laser machining a substrate (2) with a laser source (4, 8, 10) emitting pulses (P1,.., P4) of duration equal to or less than a picosecond in the form of a moving incident laser beam (6), comprising the steps of defining an engraving vector on the substrate, delimited by a starting point (D) and an ending point (A), and composed of a path to be traveled on the substrate (2) and a series of impacts of the incident laser beam (6) along the path, the laser source (4, 8, 10) being programmed such that: the first pulse (P1) associated with the first impact is emitted after the incident laser beam (6) has left the starting point (D) to begin its movement, and the last pulse (P4) associated with the last impact is emitted before the incident laser beam (6) has reached the ending point (A) and finished moving.