Coaxial Oxygen Laser Piercing With Directional Dross Clearing
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Solution Overview
Problem
Existing methods for laser cutting thick metal sections face extended cycle times and quality issues due to molten metal debris accumulation, leading to incomplete cuts and damage to cutting tools, particularly when transitioning from piercing to cutting.
Innovation Solution
A method and system using a coaxial oxygen supply and a directionally controlled air nozzle to efficiently remove molten metal and debris during piercing, enabling a rapid transition to cutting with improved quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single coaxial oxygen gas system is used for piercing and cutting thick metal, then the oxidation efficiency is improved, but the dross deposit on the bottom face increases and cycle time is extended
Solution Approach 1:
The gas delivery system is segmented into two separate nozzles: a first nozzle for delivering oxygen gas coaxially with the laser beam during piercing, and a second nozzle for delivering a clearing stream of gas (air or oxygen) at an angle to the work surface during cutting. This segmentation allows each nozzle to be optimized for its specific function, resolving the contradiction between oxidation efficiency and cycle time by enabling simultaneous dross removal without sacrificing piercing power.
Solution Approach 2:
A second gas delivery system acts as an intermediary between the laser cutting process and the environment. The clearing stream from the second nozzle serves as a mediator that removes dross and molten metal from the cut path without interfering with the primary oxidation process of the first nozzle, thereby reducing cycle time while maintaining cutting efficiency.
2Power
If laser power is increased to address dross buildup, then the cutting power is improved, but the piercing hole diameter increases and molten metal clogging occurs
Solution Approach 1:
The gas delivery function is segmented between two nozzles, allowing the first nozzle to maintain lower, more controlled power settings for precise piercing hole formation while the second nozzle provides enhanced clearing capability. This segmentation resolves the contradiction by decoupling the need for high power from the need for precise hole diameter control.
3Productivity
If piercing speed is increased by raising peak laser output, then the productivity is improved, but the sputter adhesion to lens and nozzle increases
Solution Approach 1:
The second gas delivery system acts as an intermediary that removes sputter and molten metal debris from the piercing and cutting zones. By introducing this clearing stream at an angle to the work surface, the system can achieve higher piercing speeds without the harmful effect of sputter adhesion to the lens and nozzle, as the clearing stream continuously evacuates debris from the interaction zone.
4Device complexity
If a single gas system is used for thick plate piercing, then the device complexity is reduced, but the molten metal removal efficiency decreases
Solution Approach 1:
The gas delivery system is segmented into two separate nozzles with distinct functions: the first nozzle for oxygen delivery during piercing and the second nozzle for clearing stream delivery during cutting. Although this increases device complexity slightly, it dramatically improves molten metal removal efficiency by providing dedicated clearing capability that operates simultaneously with the cutting process, thereby resolving the contradiction in favor of productivity.
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 method achieves a controlled piercing with a rapid transition to cutting, reducing cycle time and ensuring high-quality cuts by preventing excess melting and smooth removal of molten metal, even in thick plates exceeding 12 mm.
Implementation Method 1
The piercing operation involves the application of a high energy laser beam from a cutting nozzle to plunge an initial hole into the metal plate, heating the plate
Implementation Method 2
The application of oxygen gas during the piercing operation enhances the piercing operation by increasing the efficiency of the cutting operation. This results because increased energy is obtained as a result of the oxidation of the molten material by the flow of the oxygen gas
Implementation Method 3
supplying an assist gas which is coaxial to the laser beam, in order to form the piercing hole by removing the molten metal from the heated part of the plate by the kinetic energy of the assist gas
Data Source
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AI summary
A method and system is provided for laser piercing of thick plate material that allows for rapid transition to a cutting operation that can reliably produce a piercing hole and complete a cutting operation of the intended shape in a short time, while improving the cutting quality of the cutting after switching from the piercing operation. The cutting nozzle has a centrally located laser. The piercing operation applies a laser beam to the cut work while axially supplied pure oxygen gas is applied towards the cutting work. Additionally, a direction controlled nozzle adjacent the main cutting port provides a discharge of high pressure compressed air non-axially relative to the cutting operation to clear excess molten metal and debris from the kerf thereby increasing the efficiency of the piercing and shortening the cycle time.