Transient beam oscillation with a highly dynamic scanner for laser beam fusion cutting

Abstract

Sheet metals with thicknesses >8 mm have a distinct cutting performance. The free choice of the optical configuration composed of fiber diameter, collimation, and focal length offers many opportunities to influence the static beam geometry. Previous analysis points out the limitations of this method in the thick section area. Within the present study, an experimental investigation of fiber laser fusion cutting of 12 mm stainless steel was performed by means of dynamical beam oscillation. Two standard optical setups are combined with a highly dynamic galvano-driven scanner that achieves frequencies up to 4 kHz. Dependencies of the scanner parameter, the optical circumstances, and the conventional cutting parameters are discussed. The aim is to characterize the capabilities and challenges of the dynamic beam shaping in comparison to the state-of-the-art static beam shaping. Thus, the trials are evaluated by quality criteria of the cut edge as surface roughness and burr height, the feed rate, and the cut kerf geometry. The investigation emphasizes promising procedural possibilities for improvements of the cutting performance in the case of fiber laser fusion cutting of thick stainless steel by means of the application of a highly dynamic scanner

Improvement of Laser Beam Fusion Cutting of Mild and Stainless Steel Due to Longitudinal, Linear Beam Oscillation

“…A highly dynamic scanner initiated the beam oscillation and was integrated into a standard cutting head [31]. The used scanner achieved oscillation frequencies up to 4 kHz.…”

“…All these methods have in common that they belong to static beam shaping methods. This means that the properties of the laser beam are modified before the cutting process takes place [30,31]. One of the most promising methods to improve LBFC of thick metal plates is the enlargement of the focal radius [8,32].…”

“…That implies a superimposed modification of the laser beam movement regarding the feed direction. Thus, the beam oscillates inside the generated cut kerf and thereby shapes the interaction area into an arbitrary geometry [30,31]. A main advantage of beam oscillation concept is the preserved intensity distribution of the fiber laser beam at simultaneously increased interaction area between laser beam and melt.…”

“…Two of the most relevant processes using beam oscillation are electron [33,34] and laser beam welding [35][36][37][38]. In addition, first investigations on laser beam flame cutting of mild steel [39][40][41] and LBFC of stainless steel [2,30,31] have been performed with beam oscillation. All these investigations have demonstrated a high potential of process improvements regarding less process instabilities, faster processing speed, and advanced quality.…”

Revisiting image-based quality evaluation of laser cut edges

“…Therefore, it is necessary to measure dross as a quality factor and accordingly determine the post-processing requirements based on industrial demands. Different techniques based on image processing have been proposed to measure the average dross height [15,16]. Employing these methods, the cut edge is divided into a few sections and the maximum dross height is determined in each area.…”