Double Nozzle Assist Gas Flow for Low-Bevel Laser Cutting
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Solution Overview
Problem
Existing laser cutting nozzles experience increased bevel and kerf width when cutting thick mild steel sheets with fiber lasers, leading to unstable and ineffective cutting processes.
Innovation Solution
A double nozzle design that divides assist gas into inner and outer flows, with a specific flow ratio adjustment based on sheet thickness, and a unique nozzle structure featuring a tube-shaped inner nozzle with a decreasing diameter and notches, and an outer nozzle with a vent passage matching the notch opening area, to control the assist gas flow and minimize bevel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional double nozzle is used for cutting thick mild steel sheets with fiber laser, then the cutting process can be performed, but the amount of bevel increases and kerf width widens
Solution Approach 1:
The assist gas flow is segmented into inner flow and outer flow components. The inner nozzle emits laser beam and inner assist gas flow through its center hole, while the outer nozzle provides outer assist gas flow through bypass notches. This segmentation allows independent control of gas flow paths to optimize cutting performance and reduce bevel.
Solution Approach 2:
The nozzle structure implements local quality by providing different gas flow characteristics at different locations. The inner flow concentrates gas at the laser beam path for precise cutting, while the outer flow provides cooling and debris removal at the kerf walls. The flow ratio is locally optimized based on workpiece thickness.
2Productivity
If assist gas flow rate is increased to improve cutting speed, then productivity increases, but bevel amount and kerf width increase further
Solution Approach 1:
The system implements dynamic control by adjusting the flow ratio between inner and outer assist gas flows based on workpiece thickness. For thicker materials, a higher outer flow ratio provides better cooling and debris evacuation without excessive overall gas consumption, maintaining kerf width control while enabling higher cutting speeds.
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 approach enables stable and effective cutting of mild steel sheets regardless of thickness, maintaining a controlled bevel and kerf width, improving cutting quality and consistency.
Implementation Method 1
a laser beam LS supplied from a fiber laser oscillator (not illustrated) to the nozzle 51 is focused by a focusing lens 63
Implementation Method 2
a part of the supplied assist gas is jetted downward through the output port 2b of the through hole 2 as the inner flow FL1, and the remaining part of the supplied assist gas enters from an inflow opening GRa1 to an upper vent passage GRa
Data Source
AI summary
A laser cutting nozzle includes an inner nozzle and an outer nozzle. The inner nozzle exhibits a tube shape having a through hole on an axis and having a diameter decreasing on a first end portion side and includes a notch extending in the axis direction along an outer peripheral surface on a second end portion side. The outer nozzle is fitted to the outer peripheral surface of the inner nozzle and includes a vent passage including the notch and communicating between the first end portion and the second end portion in the axis direction. A minimum flow cross-sectional area of the vent passage matches an opening area of the notch in an end surface on the second end portion side.