Laser Piercing Control for Stable Molten Layer Intensity
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Solution Overview
Problem
The existing laser piercing methods for metallic workpieces face issues with process instabilities and overheating, leading to metal splashes that damage the protective glass of the cutting head, affecting cutting quality and requiring frequent replacements, and increasing production downtime.
Innovation Solution
A method and device for piercing using a processing laser beam that includes real-time monitoring of radiation intensity values within the molten layer, adjusting process parameters to maintain a critical radiation intensity value below the threshold for evaporation or instability, using dynamic beam shaping, power modulation, and gas pressure control to optimize piercing quality and minimize duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high laser power is applied to reduce piercing time, then productivity increases, but process instabilities and overheating occur leading to metal splashes that damage protective glass
Solution Approach 1:
The patent applies dynamic beam shaping that continuously adjusts the beam cross-section during the piercing process. The beam is divided into multiple sub-beams with different focal points distributed along the penetration depth, allowing adaptive energy distribution that prevents overheating while maintaining high piercing speed. This dynamic adjustment resolves the contradiction by enabling high productivity without causing process instabilities that would damage the protective glass.
Solution Approach 2:
The patent changes multiple process parameters simultaneously including beam diameter, focal position, and power distribution along the beam path. By dynamically modifying these parameters during piercing, the system maintains optimal energy density throughout the workpiece thickness, preventing local overheating and metal splashes while achieving rapid piercing. This multi-parameter control resolves the contradiction between fast piercing and protective glass preservation.
2Manufacturing precision
If laser power is increased to improve piercing quality, then manufacturing precision improves, but metal splatter increases damaging the protective glass
Solution Approach 1:
The patent segments the laser beam into multiple sub-beams with different focal points distributed along the penetration depth. Each sub-beam processes a specific layer of the workpiece, preventing excessive energy concentration that would cause metal splatter. This segmentation maintains high piercing quality while eliminating the harmful splatter effect, resolving the contradiction between precision and splatter generation.
Solution Approach 2:
The patent introduces process gas as an intermediary medium that interacts with the molten metal in the keyhole. The gas pressure and flow are dynamically controlled to stabilize the melt pool and prevent metal splashes from escaping. This intermediary gas layer protects the protective glass from splatter damage while allowing high-power laser processing to maintain piercing quality.
3Reliability
If nozzle distance is increased to reduce metal splash impact on protective glass, then protective glass is protected, but piercing time increases reducing productivity
Solution Approach 1:
The patent replaces the mechanical solution of increasing nozzle distance with an optical solution of dynamic beam shaping. By controlling the energy distribution and focal points within the beam, the system prevents metal splatter generation at the source without requiring increased nozzle distance. This substitution maintains both protective glass lifespan and high piercing productivity, resolving the contradiction between the two parameters.
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 method prevents local overheating and process instabilities, optimizing piercing behavior, reducing spatter, and minimizing piercing time while maintaining high-quality cutting processes.
Implementation Method 1
detecting process light generated in the molten layer by the processing laser beam
Implementation Method 2
piercing the workpiece once or several times with the processing laser beam, creating a process zone with a molten layer
Data Source
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AI summary
A method for piercing a metallic workpiece is described, comprising generating a processing laser beam with a laser source (S1); guiding the processing laser beam onto the workpiece using an optical arrangement (S2); piercing the processing laser beam into the workpiece, thereby creating a process zone with a molten layer (S3); and detecting process light generated in the molten layer by the processing laser beam (S4). A plurality of radiation intensity values of the molten layer are spatially resolved or areally integrated and temporally resolved based on the detected process light (S5).At least one of the determined radiation intensity values is regulated to a target radiation intensity value equal to or less than the critical radiation intensity value upon reaching a critical radiation intensity value (S6) by adjusting at least one process parameter of the procedure selected from a laser source power; a laser source pulse duty cycle; a beam-shaping dynamic movement of the processing laser beam; a focal plane position of the processing laser beam; a focus diameter of the processing laser beam; and a magnification of the processing laser beam. The critical radiation intensity value is determined at a time point before the onset of vaporization of a material in the melt layer and/or process instability.