Laser Cutting Nozzle Gap Control to Prevent End-Cut Tilting

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Solution Overview

Problem

Laser cutting of plate-shaped workpieces, especially with movable nozzle sleeves, often results in tilting of cut workpiece parts due to cutting gas pressure, leading to contamination of the cutting nozzle and optical components as the slag is thrown upwards instead of escaping downwards.

Innovation Solution

Increasing the distance between the cutting nozzle and the workpiece surface along a predetermined final section before the cut-off point, ensuring a gap for lateral escape of cutting gas, sparks, and slag, thereby preventing tilting and contamination. This distance is maintained at least 0.3 mm to 1 mm at the cut-off point, and can be increased abruptly or gradually, while keeping the focal position of the laser beam constant.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the distance between the cutting nozzle and the workpiece surface is small to maintain precise cutting control, then cutting precision is improved, but the workpiece part tilts due to cutting gas pressure causing contamination

Engineering Contradiction:
Improvecutting precisionVSAvoidprocess reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The distance between the cutting nozzle and the workpiece surface is dynamically adjusted during the cutting process. The method increases the distance on a predetermined final section in front of the cut-off point, allowing the system to transition from a small distance (for precision) to a larger distance (to prevent tilting and contamination) at the appropriate moment in the cutting sequence.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the distance between the cutting nozzle and the workpiece surface is increased to prevent tilting and contamination, then process reliability is improved, but cutting precision deteriorates

Engineering Contradiction:
Improveprocess reliabilityVSAvoidcutting precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The distance increase is applied locally only to a predetermined final section in front of the cut-off point, rather than increasing the distance throughout the entire cutting contour. This localized adjustment maintains precise cutting control for the majority of the cut while preventing tilting and contamination only where needed at the end of the cutting process.

Inventive Principle:
Principle #3Local quality

3Reliability

If microjoints are used to fix workpiece parts to prevent tilting, then process reliability is improved, but the workpiece surface quality deteriorates due to remaining marks

Engineering Contradiction:
Improveprocess reliabilityVSAvoidsurface quality
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The method extracts or removes the need for microjoints by instead increasing the nozzle distance to prevent tilting. This eliminates the harmful side effect of microjoint marks on the workpiece surface while maintaining the beneficial effect of preventing workpiece tilting and contamination.

Inventive Principle:
Principle #2Taking out (Extraction)

4Reliability

If the laser cutting head is moved to increase distance after cut-off to prevent contamination, then process reliability is improved, but productivity deteriorates due to additional movement time

Engineering Contradiction:
Improveprocess reliabilityVSAvoidcutting speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The distance increase is performed as a preliminary action on the final section before the actual cut-off point is reached. By preparing the larger gap in advance during the cutting traverse, the method eliminates the need for additional post-cut movement to prevent contamination, thereby maintaining cutting speed while ensuring process reliability.

Inventive Principle:
Principle #10Preliminary action

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 process reliability by preventing tilting of cut workpieces and reducing contamination of the cutting nozzle and optical components, ensuring efficient expulsion of slag downwards without spattering, even with a movable nozzle sleeve.

Implementation Method 1

a laser beam and a cutting gas emerging from a cutting nozzle (9)

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 2

the melted workpiece material (the slag)

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

the gas pressure of the cutting gas acts on the workpiece part at the free cut point

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Implementation Method 4

the cutting gas, sparks, smoke and any slag can escape laterally

Methodology Applied
Scientific EffectFluid flow: Fluid Spray

Data Source

PatentEP3774164B1Laser cutting method with an increased cutting nozzle distance at the end of the cut, laser cutting machine and computer program product
Publication Date: 2022.07.06 TRUMPF WERKZEUGMASCHINEN GMBH & CO KG
  • EP3774164B1 patent drawingFigure 1
  • EP3774164B1 patent drawingFigure 2a~2f
  • EP3774164B1 patent drawingFigure 3a~3b

AI summary

The invention relates to laser cutting method for cutting a self-contained cut contour (8) into a preferably flat workpiece (2) by means of a laser beam (3) and a cutting gas (10) emitted from a cutting nozzle (9). According to the invention, the distance (A) of the cutting nozzle (9) relative to the workpiece surface (2a) is increased on or along a predefined final stretch (13) before the free point of punch (E) of a workpiece (11) cut free by the cut contour (8).