Optimization of an off-axis nozzle for assist gas injection in laser fusion cutting

• Published in: Optics and lasers in engineering 2006-11, Vol.44 (11), p.1158-1171
• Main Authors: Quintero, F., Pou, J., Fernández, J.L., Doval, A.F., Lusquiños, F., Boutinguiza, M., Soto, R., Pérez-Amor, M.
• Format: Article
• Language: English
• Subjects: Assist gas; Biological and medical applications; Exact sciences and technology; Flow visualization; Fluid dynamics; Fundamental areas of phenomenology (including applications); Industrial applications; Instrumentation for fluid dynamics; Laser cutting; Optical elements, devices, and systems; Optics; Physics; Schlieren devices
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2005.10.001

The aerodynamic features of the gas flow during laser fusion cutting are an essential factor influencing the cut performance. For this reason it has been a subject of some studies to explain the interactions of the gas jet with the workpiece and to design different gas injection systems with the aim of preventing the drawbacks of the conventional cutting heads. An off-axis cutting head with a de Laval nozzle to inject a supersonic gas jet has been previously demonstrated to be an effective design to achieve a complete removal of the molten material from the cutting front and to avoid the formation of the recast layer. In the present work, the fundamentals and procedures to adjust the main factors determining the efficiency of this gas injection system are described. Specifically, the gas flow inside the cut kerf is analysed by means of flow visualization using the Schlieren technique.