Laser Cutting Nozzle Riblets for Laminar Assist Gas Flow
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Solution Overview
Problem
Existing laser cutting machines face challenges in achieving efficient gas flow due to issues like gas loss and turbulence, particularly when dealing with workpieces having salient features or unevenness, and the use of wear-resistant sleeves is costly and prone to damage.
Innovation Solution
The implementation of a laser machining nozzle with a flow guiding section featuring riblets, which are small ribs parallel to the fluid flow direction, reduces gas turbulence and enhances laminar flow, allowing for more efficient gas coupling into the cut with lower pressure requirements and improved cut quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a sleeve is used to direct the gas jet onto the workpiece, then gas flow is confined and laminar flow is produced, but the workpiece may be damaged or displaced and the sleeve is expensive and prone to damage
Solution Approach 1:
The invention removes the external sleeve component and extracts only the essential flow-guiding function, integrating it directly into the nozzle wall through riblets. This eliminates the sleeve that causes workpiece damage while preserving the laminar flow generation capability.
Solution Approach 2:
The flow-guiding riblets are nested within the nozzle structure itself, with the riblet pattern integrated into the nozzle wall. This nested integration allows the nozzle to perform both its primary gas delivery function and the secondary flow-guiding function without requiring an external sleeve.
2Productivity
If high-pressure gas jets are used to assist cutting, then material removal is enhanced, but gas flow losses increase and cut roughness increases
Solution Approach 1:
The invention changes the flow regime parameter from turbulent to laminar by introducing riblets. This parameter change allows effective cutting at lower gas pressures, reducing gas flow losses while maintaining cutting productivity. The riblet-induced laminar flow improves gas coupling efficiency into the cut.
3Power
If turbulent gas flow is used for cutting, then material removal is effective, but gas coupling efficiency into the cut decreases
Solution Approach 1:
Instead of using turbulent flow to achieve material removal, the invention inverts the approach by using laminar flow with riblets to guide the gas jet. This inversion demonstrates that laminar flow can achieve effective cutting with improved gas coupling efficiency, contrary to conventional wisdom that requires turbulence.
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 use of riblets in the nozzle leads to reduced gas flow losses, minimized cut roughness and burr formation, and controlled energy deposition, resulting in improved cutting efficiency and quality without the need for high-pressure gas jets.
Implementation Method 1
The riblets run in an axial direction, i.e. the riblets are parallel to the direction of the fluid flow through the nozzle... reduces gas turbulence and enhances laminar flow
Implementation Method 2
reduces gas turbulence and enhances laminar flow, allowing for more efficient gas coupling into the cut
Data Source
Figure 1~4
Figure 5~6
AI summary
The present invention concerns a laser cutting machine with a cutting head that moves relative to a workpiece for making a controlled cut in the workpiece. The cutting head comprises a laser machining nozzle (20) and a gas supply mechanism and is equipped to eject a gas jet from the laser machining nozzle (20) onto the workpiece when the workpiece is supported by the support. The laser machining nozzle (20) has a flow guiding section that is provided with a plurality of riblets (25) that may especially run in an axial direction, i.e. the riblets (25) are parallel to the direction of the fluid flow through the nozzle (20). The riblets (25) make the fluid flow through the nozzle (20) more laminar.