Pulsed Laser Contour Machining with Irrational Frequency Ratio
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Solution Overview
Problem
Pulsed laser machining methods for creating large holes or contours face challenges in achieving efficient material removal without surface distortion, as the tool diameter is often smaller than the hole, requiring complex parameter tuning and leading to suboptimal machining times and results.
Innovation Solution
The method optimizes the instantaneous frequency ratio of the pulse frequency and rotational frequency of the tool to achieve a high degree of coverage with the fewest rotations, using an irrational frequency ratio to ensure effective distribution of machining pulses without direct concatenation, thereby minimizing heat input and machining time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the machining frequency is increased to improve material removal efficiency, then the productivity increases, but the workpiece becomes distorted due to one-sided heat input and the locally narrow heat input advantage is lost
Solution Approach 1:
The patent applies periodic action by using pulsed laser operation instead of continuous wave operation. The laser emits short, high-energy pulses at frequency fL, creating periodic heating cycles that allow heat dissipation between pulses. This prevents cumulative one-sided heat input distortion while maintaining high material removal rates through repeated ablation cycles.
Solution Approach 2:
The patent segments the continuous machining process into discrete pulses. By dividing the continuous laser beam into separate high-energy pulses, the process removes material in controlled increments while allowing heat to dissipate between pulses, preventing workpiece distortion associated with continuous heating.
2Manufacturing precision
If very slow, one-time traversal of the contour is used to achieve coverage of individual ablations, then the manufacturing precision improves, but the machining duration becomes excessively long
Solution Approach 1:
The patent maintains continuity of useful action by performing multiple traversals of the contour at optimized speed. Rather than one slow pass, the system repeatedly traverses the contour with pulsed laser operation, keeping the tool engaged in productive machining throughout multiple cycles, thereby reducing total machining time while achieving complete material removal.
Solution Approach 2:
The patent changes key parameters including pulse frequency fL, rotational frequency fCNC, and their frequency ratio φ to optimize the machining process. By adjusting these parameters, the system achieves complete coverage of ablations through multiple faster passes rather than one slow pass, reducing machining duration while maintaining precision.
3Manufacturing precision
If repeated traversal of the contour is performed to achieve complete coverage of ablations, then the manufacturing precision improves, but the machining time increases and parameter tuning becomes complex
Solution Approach 1:
The patent employs feedback by calculating and optimizing the frequency ratio φ = fL/fCNC to achieve optimal coverage patterns. The system uses mathematical relationships between pulse frequency and rotational frequency to determine the minimum number of rotations needed for complete coverage, eliminating the need for time-consuming trial-and-error parameter tuning.
Solution Approach 2:
The patent replaces complex mechanical trial-and-error parameter tuning with mathematical calculation. By using the frequency ratio relationship and contour length calculations, the system determines optimal parameters through computation rather than iterative mechanical adjustment, significantly reducing setup time and complexity.
4Adaptability or versatility
If the tool diameter is significantly smaller than the hole diameter, then the versatility of the laser tool is improved, but the quantity of machined material per pulse decreases, requiring more rotations and increasing machining time
Solution Approach 1:
The patent applies dynamics by optimizing the relationship between tool size, pulse frequency, and rotational speed. The system dynamically adjusts the frequency ratio φ and number of rotations based on the specific contour and material thickness, allowing a small-diameter laser tool to efficiently machine large holes by distributing pulses optimally across multiple rotational cycles.
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 approach results in efficient material removal with reduced machining time and minimized surface distortion, allowing for precise and complete contour machining without the need for lengthy parameter tuning or excessive rotations.
Implementation Method 1
Due to the locally high energy input, material is vaporized; thus, in the optimal case, no molten material is produced which would have to be expelled and could lead to impurities and to a degradation of the surface quality
Data Source
AI summary
A pulsed machining method for the optimized machining of a contour which is characterized in that the instantaneous frequency ratio of φ of the pulse frequency of tool fL and of the rotational frequency of tool fCNC is optimized to achieve a highest possible degree of coverage of the individual machining pulses in the context of a shortest possible machining duration and without a direct concatenation of the machining pulses. It is especially preferred that this be achieved in that frequency ratio φ is an irrational number, thus cannot be expressed by the ratio of two whole numbers. By applying the method according to the present invention, a considerable time savings is achieved since there is no longer a need for time-consuming preliminary trials to ascertain an at least sufficient frequency ratio φ.