Fundamental study of CO2- and fiber laser cutting of steel plates with high speed visualization technique

Ermolaev, G. V.; Yudin, P. V.; Briand, Francis; Zaitsev, Alexandr V.; Ковалев, О. Б.

doi:10.2351/1.4895563

Cited by 23 publications

(5 citation statements)

References 16 publications

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“…Few reports are found on the experimental investigation of the effect of cut front slope, representing the cutting velocity, and the periodical change of cutting front slope under different cutting parameters. 9,10 Moreover, it is unclear how the displacement between nozzle axis and cut front affects flow separation, representing different focal point position during laser cutting thick sections. Effect of a kerf wider than 2 mm representing LASOX process on flow separation has not been studied.…”

Section: Introductionmentioning

confidence: 99%

Visualization of flow separation inside cut kerf during laser cutting of thick sections

Zhang

Wen

Yao

et al. 2016

Journal of Laser Applications

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The behavior of oxygen gas not only determines the oxidation heat input but also affects the removal of molten metal during laser-oxygen cutting. Flow separation inside the cut kerf is the major problem for the deterioration of cut ability and cut quality, especially for cutting thick steel sections, because it significantly weakens the shear stress on molten slag and changes the pressure gradient along the cut front. There have been some researches on flow separation using numerical simulation and model kerf. However, many experimental details and results are unclear, and the numerical simulation is questionable due to lack of experimental verification. In this paper, a model kerf is set up based on the previous results of observation and cutting trials. High resolution and high speed Schlieren visualization is used to observe the formation of flow separation in the model kerf. Stand-off distance, inlet pressure, cut front slope, nozzle displacement, kerf width, and nozzle tilting angle are used as variables for Schlieren visualization of flow separation for both a conical subsonic and a minimum length nozzle supersonic nozzle. The effect of the above parameters on the position and the pattern of flow separation is discussed based on the gas dynamic theory. It is found that nozzle displacement, kerf width, and nozzle tilting angle are the key factors for flow separation. Possible strategies for controlling flow separation are also proposed for both subsonic and supersonic nozzles.

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Section: Introductionmentioning

confidence: 99%

Visualization of flow separation inside cut kerf during laser cutting of thick sections

Zhang

Wen

Yao

et al. 2016

Journal of Laser Applications

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“…In addition, the ring mirror allows a movement direction independent sensing, which is not possible in lateral offset mounted sensors (e.g., the system from Golubev et al [18]). In contrast to camera-based sensing, which allows to calculate more cutting characteristics, such as kerf width or striations [14], the here-demonstrated system requires less calculation effort and, therefore, shorter reaction times.…”

Section: Evaluation and Discussion Of The Sensor And Algorithmmentioning

confidence: 99%

“…Sichani et al [13] also applied an IR camera to monitor the kerf width, dross, and striations during fusion cutting of mild steel. A high speed camera in the same plane with the metal sheet is used by Ermolaev et al [14] to visualize the melt flow during the cutting process with a fiber and CO2 laser. With this system, it can be proven that the striation formation is caused by cyclic melt removal.…”

Section: Introductionmentioning

confidence: 99%

Optical Cutting Interruption Sensor for Fiber Lasers

Adelmann

Schleier

Neumeier³

et al. 2015

Applied Sciences

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Abstract:We report on an optical sensor system attached to a 4 kW fiber laser cutting machine to detect cutting interruptions. The sensor records the thermal radiation from the process zone with a modified ring mirror and optical filter arrangement, which is placed between the cutting head and the collimator. The process radiation is sensed by a Si and InGaAs diode combination with the detected signals being digitalized with 20 kHz. To demonstrate the function of the sensor, signals arising during fusion cutting of 1 mm stainless steel and mild steel with and without cutting interruptions are evaluated and typical signatures derived. In the recorded signals the piercing process, the laser switch on and switch off point and waiting period are clearly resolved. To identify the cutting interruption, the signals of both Si and InGaAs diodes are high pass filtered and the signal fluctuation ranges being subsequently calculated. Introducing a correction factor, we identify that only in case of a cutting interruption the fluctuation range of the Si diode exceeds the InGaAs diode. This characteristic signature was successfully used to detect 80 cutting interruptions of 83 incomplete cuts (alpha error 3.6%) and system recorded no cutting interruption from 110 faultless cuts (beta error of 0). This particularly high detection rate in combination with the easy integration of the sensor, highlight its potential for cutting interruption detection in industrial applications. OPEN ACCESSAppl. Sci. 2015, 5 545

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“…Inherent dependencies on laser wavelength as well as processing parameters were also discussed in detail [24,25]. Ermolaev et al [26] used the trim-cut method to visualize the melt flow in inert-gas cutting stainless steel sheets of 6 mm thickness by CO 2 and fiber laser radiation and found that the type of radiation, i.e., the laser wavelength, influences the liquid melt flow behavior on the cut front. They reported a melt flow destabilization in case of fiber laser cutting.…”

Section: Introductionmentioning

confidence: 99%

Factorial Analysis of Fiber Laser Fusion Cutting of AISI 304 Stainless Steel: Evaluation of Effects on Process Performance, Kerf Geometry and Cut Edge Roughness

2021

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Factorial Design-of-Experiment analyses were applied for conventional and beam oscillation fiber laser cutting of 10 mm thick AISI 304 stainless steel. Considered factors in case of the conventional process with a static beam involve both laser and cutting gas parameters, in particular the laser power, the focal plane position, the cutting gas pressure, the nozzle stand-off distance as well as the nozzle diameter. The conducted trials were evaluated with respect to the achievable cutting speed, the cut kerf geometry and the cut edge roughness. Noticeable correlations between cut edge roughness and cut kerf geometry stimulated the development of a corresponding Computational Fluid Dynamics (CFD) model of the cutting gas flow through the kerf. A specific approach of data synchronization revealed that the experimentally determined roughness values do well correlate with numerically computed values of the backward directed component of the gas-induced shear stress and that the cut kerf geometry as internal process-inherent boundary condition influences relevant cutting characteristics more than controllable external cutting gas parameters. Finally, effects of circular beam oscillation were investigated by an additional factorial analysis considering the laser power, the focal plane position, the oscillation frequency and the oscillation amplitude as factors. The results demonstrate the potential of beam oscillation techniques for quality improvements in laser cutting.

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Fundamental study of CO2- and fiber laser cutting of steel plates with high speed visualization technique

Cited by 23 publications

References 16 publications

Visualization of flow separation inside cut kerf during laser cutting of thick sections

Visualization of flow separation inside cut kerf during laser cutting of thick sections

Optical Cutting Interruption Sensor for Fiber Lasers

Factorial Analysis of Fiber Laser Fusion Cutting of AISI 304 Stainless Steel: Evaluation of Effects on Process Performance, Kerf Geometry and Cut Edge Roughness

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