Laser Cutting Nozzle Focus Position for Thick Metal Edge Quality

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Solution Overview

Problem

Conventional laser cutting machines face challenges in maintaining high cutting quality for thick workpieces due to limited adjustability of the focus position and increased heating, which leads to reduced edge quality and increased costs.

Innovation Solution

A cutting method with a nozzle orifice diameter of at most two millimeters and a focus position above the nozzle mouth, with a maximum distance along the center axis of the laser beam from the nozzle mouth of at most sixteen times the mouth diameter, allowing for precise control of the focus position and reducing unwanted heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the focus position is moved further away from the workpiece to ensure sufficient cutting quality in thick workpieces, then cutting quality is improved, but the laser beam spreads more widely causing pronounced edge region heating that impairs cut quality

Engineering Contradiction:
Improvecutting qualityVSAvoidedge region heating
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the focus position parameter to be within a specific range (0.5mm to 5mm above the workpiece surface) and adjusts the nozzle diameter parameter (0.6mm to 15% of workpiece thickness) to optimize the balance between cutting quality and edge region heating control

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent makes the focus position adjustable and dynamic, allowing it to be moved to different positions above the workpiece surface depending on the specific cutting requirements and workpiece thickness, rather than being fixed at a single position

Inventive Principle:
Principle #15Dynamics

2Device complexity

If conventional focusing optics are used with limited adjustability of focus position, then device complexity is reduced, but cutting quality for thick workpieces deteriorates

Engineering Contradiction:
Improvefocusing optics complexityVSAvoidcutting quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent introduces dynamic adjustability to the focus position within the focusing optics, enabling the focus to be moved to different positions above the workpiece surface. This dynamic capability allows conventional focusing optics to achieve high cutting quality on thick workpieces without requiring completely new optical systems

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If the nozzle diameter is increased to allow higher focus position, then ease of operation is improved, but cutting gap width increases reducing cutting quality

Engineering Contradiction:
Improvefocus position adjustmentVSAvoidcutting gap width
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent optimizes the nozzle diameter parameter to be within a specific range (0.6mm to 15% of workpiece thickness) and combines it with an optimized focus position (0.5mm to 5mm above workpiece surface). This parameter optimization allows sufficient focus adjustment range while maintaining narrow cutting gap width for high cutting quality

Inventive Principle:
Principle #35Parameter changes

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 enhances cutting quality by maintaining a narrow cutting gap, reducing melt and enabling tighter curves, while preventing excessive heating and extending the service life of the cutting nozzle.

Implementation Method 1

laser beam cutting of metallic workpieces

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 2

This heating can subsequently lead to melting of the workpiece

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

the focus of the laser beam is moved further away from the workpiece as the workpiece thickness increases, in order to ensure a sufficiently high cutting quality

Methodology Applied
Scientific EffectVaporization: Evaporation

Data Source

PatentEP4215308B1Laser cutting method with focal position inside a cutting nozzle having a small opening diameter
Publication Date: 2024.07.03 TRUMPF WERKZEUGMASCHINEN GMBH & CO KG
  • EP4215308B1 patent drawingFigure 1
  • EP4215308B1 patent drawingFigure 2
  • EP4215308B1 patent drawingFigure 3~4

AI summary

The invention relates to a cutting method for laser beam cutting of metallic workpieces (14) with a workpiece thickness (52) of at least ten millimeters, with a laser power of at least ten kilowatts, wherein a nozzle opening (38) of a cutting nozzle (32) has an opening diameter of at most two millimeters and wherein a focus (34) of a laser beam (22) is arranged above the nozzle opening (38) and has a maximum distance along a central axis (42) of the laser beam (22) from the nozzle opening (38) which is at most sixteen times the opening diameter.