Convergent-Divergent Laser Cutting Nozzle for Stable 3D Gas Jets
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Solution Overview
Problem
Modern laser machining units face challenges in maintaining precise cutting parameters, leading to quality losses and increased risk of component collisions when machining complex three-dimensional workpieces, especially at high speeds and small nozzle distances, due to limitations in controlling the nozzle-workpiece distance and the characteristics of the cutting gas jet.
Innovation Solution
A laser cutting nozzle with a convergent-divergent passage design, where the wall inclination is limited to at most 5° in the divergence portion and the length is less than 5 times the diameter of the constriction, ensuring effective gas jet shaping and maintaining constant fluid dynamic ratios over a large distance, allowing the cutting gas to reach supersonic speed and be retained effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the nozzle-workpiece distance is reduced to increase machining speed, then productivity is improved, but the risk of component collisions increases and manufacturing precision deteriorates
Solution Approach 1:
The patent changes the geometric parameters of the nozzle passage, specifically implementing a convergent-divergent profile with optimized angles (convergence angle 5-15°, divergence angle 5-10°) and length ratios. This parameter optimization allows the gas jet to maintain supersonic speed and stable characteristics over extended distances, enabling high-speed machining while preserving cutting quality and reducing collision risks through increased working distance tolerance.
2Reliability
If the nozzle-workpiece distance is increased to reduce collision risk, then reliability is improved, but manufacturing precision deteriorates due to gas flow detachment
Solution Approach 1:
The patent creates a dynamic gas flow regime by designing the passage to accelerate the cutting gas to supersonic speeds in the convergent section and maintain stable expansion in the divergent section. This dynamic flow regime prevents flow detachment and maintains jet coherence over extended distances, allowing increased nozzle-workpiece distance for collision avoidance while preserving cutting precision through sustained gas flow effectiveness.
3Device complexity
If a simple conical passage is used for the nozzle, then device complexity is reduced, but manufacturing precision deteriorates due to inadequate gas jet shaping
Solution Approach 1:
The patent optimizes specific geometric parameters of the passage profile, including the convergence angle (5-15°), divergence angle (5-10°), and the ratio of passage lengths. These parameter changes transform the simple conical passage into an optimized convergent-divergent profile that effectively shapes the gas jet, improving cutting quality while maintaining relatively simple nozzle structure suitable for manufacturing.
4Manufacturing precision
If the passage length is increased to improve gas jet shaping, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent optimizes the length parameters of the convergent and divergent sections, establishing specific ratio relationships between these sections and the constriction diameter. This parameter optimization achieves effective gas jet shaping and supersonic flow maintenance within compact dimensions, improving manufacturing precision while controlling device complexity through optimized proportions rather than simply increasing overall size.
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 nozzle design improves cutting results by maintaining consistent gas flow and preventing flow detachment, enabling high-quality three-dimensional laser cutting with reduced risk of collisions and increased machining speed reliability, even at larger working distances and high feed rates.
Implementation Method 1
the passage converging continuously, towards the mouth thereof, in a convergence portion, as far as a constriction of the passage, to less than 40% of the cross-sectional area at the inlet of the convergence portion, the passage diverging continuously in a divergence portion, proceeding from the constriction, as far as the mouth of the passage, to over 130% of the cross-sectional area at the constriction
Implementation Method 2
allowing the cutting gas to reach supersonic speed and be retained effectively
Implementation Method 3
the characteristics of the cutting gas jet emerging from the nozzle have a significant influence on the quality of the cutting results
Data Source
AI summary
A laser cutting nozzle for a laser machining unit is described, the nozzle including a passage for the laser beam and cutting gas. The passage extends between a nozzle inlet and a nozzle mouth along a passage longitudinal axis. The passage comprises a convergence portion and a divergence portion. In the entire divergence portion, the wall of the passage forms an angle of inclination relative to the passage longitudinal axis of at most 5°. In addition, the length of the divergence portion is less than 5 times the diameter of the constriction.