Laser Piercing Thick Metal Workpieces with Segmented Gas Flow
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Solution Overview
Problem
During laser-cutting, bulges of melted and resolidifying metal or metal oxide form around piercing holes in thick workpieces, causing adhesion issues and interfering with cutting processes, especially in inner geometries and small components, where the cutting contour is close to the piercing site, leading to processing problems.
Innovation Solution
A three-step piercing method using a laser beam and process gases, where a partially pierced hole is formed with inert gas, followed by widening the upper part of the hole using oxygen to create a funnel-shaped structure, and finally piercing through with oxygen, minimizing heat input and slag adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is used to pierce thick workpieces, then piercing speed and productivity are improved, but bulges of melted metal form around the piercing hole causing adhesion issues and interfering with subsequent cutting processes
Solution Approach 1:
The piercing process is divided into three distinct steps: (1) forming a partial piercing hole with inert gas at low power, (2) widening the upper part into a funnel shape with oxygen, and (3) completing the piercing through the workpiece. This segmentation allows each step to address specific problems, preventing bulge formation while maintaining high productivity.
Solution Approach 2:
Before the main piercing operation, a preliminary funnel-shaped cavity is created in the upper part of the workpiece. This preliminary action provides a reservoir for molten metal during the subsequent piercing step, preventing it from forming bulges on the surface and interfering with cutting operations.
2Productivity
If high laser power is used to pierce thick workpieces quickly, then productivity is improved, but heat input into the workpiece increases affecting machining accuracy
Solution Approach 1:
The piercing process uses periodic action with three distinct phases: initial piercing at low power, funnel formation with medium power, and final piercing at high power. This periodic application of different power levels allows efficient piercing while controlling overall heat input to maintain machining accuracy.
Solution Approach 2:
The process dynamically changes multiple parameters including laser power (from low to high across steps), process gas type (inert to reactive), and beam diameter. These parameter changes enable fast piercing while controlling heat input by using low power initially and only applying high power when needed for final penetration.
3Adaptability or versatility
If the cutting contour runs close to the piercing site, then component design flexibility is improved, but bulges interfere with the cutting process
Solution Approach 1:
By segmenting the piercing process into three steps with different parameters, the method eliminates bulge formation that would otherwise interfere with nearby cutting contours, enabling greater design flexibility for components with tight tolerances and complex geometries.
Solution Approach 2:
The process converts the potentially harmful molten metal into a beneficial element by using it to form the funnel-shaped cavity that aids the piercing process, while preventing it from creating harmful bulges that would interfere with adjacent cutting operations.
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 reduces heat input and slag accumulation, enabling defect-free contour cuts and efficient piercing by expelling melt effectively, resulting in a clean and sharply defined piercing funnel with minimal material adherence.
Implementation Method 1
piercing the workpiece by means of the laser beam
Implementation Method 2
bulges of melted and resolidifying metal
Implementation Method 3
using oxygen as the process gas
Implementation Method 4
the process gas is only directed into the wide hole
Data Source
AI summary
Methods and systems are implemented for piercing a metal workpiece by means of a laser beam and a process gas The methods and systems form a hole in the workpiece using the laser beam and using an inert gas as the process gas, such that the formed hole extends only partially through the workpiece, widen the upper part of the hole into a trough that surrounds the hole on the top side of the workpiece using the laser beam and using oxygen as the process gas, and fully pierce the hole using the laser beam and using oxygen as the process gas.