scholarly journals Determination of the geometry of laser-cutting fronts with high spatial and temporal resolution

2021 ◽  
Vol 1135 (1) ◽  
pp. 012013
Author(s):  
Michael Sawannia ◽  
Peter Berger ◽  
Rudolf Weber ◽  
Thomas Graf
Keyword(s):  
Laser Power ◽  
High Speed ◽  
Frame Rate ◽  
Laser Fusion ◽  
Normal Vector ◽  
Local Surface ◽  
Aisi 304 ◽  
High Speed Video ◽  
Laser Fusion Cutting

Abstract The melt flow velocity and the local surface angles of the cutting front during laser fusion cutting of 10 mm AISI 304 were determined for a laser power of 8 kW and a feed rate of 2 m/min. The cut front was recorded with a polarization goniometer, which uses the polarization of the process emission to determine the local surface angles, allowing to calculate the orientation of the normal vector of the surface. The records in this work were carried out with a frame rate of 75 kHz and a spatial resolution of about 30 µm. This allowed to identify big and small structures moving down the cutting front and to determine their velocities. The approximate velocity of the small structures was 9.1 m/s and for the big structures approx. 2.5 m/s. The information of a usual high-speed video was compared with the additionally obtained geometry information.

scholarly journals CNN-based visual analysis to study local boiling characteristics

2021 ◽  
Vol 2119 (1) ◽  
pp. 012068
Author(s):  
A N Chernyavskiy ◽  
I P Malakhov
Keyword(s):  
Network Architecture ◽  
High Speed ◽  
Visual Analysis ◽  
Nucleation Site ◽  
High Speed Video ◽  
Site Density ◽  
Segmentation Approach ◽  
Nucleation Site Density ◽  
Instance Segmentation

Abstract Visual analysis allows an estimate of different local boiling characteristics including bubble growth rate, departure diameters and frequencies of nucleation, nucleation site density and evolution of bubbles and dry spots in time. At the same time, visual determination of the presented characteristics in case of big amounts of data requires the development of the appropriate software which will allow not only determination of bubble location, but also an estimate of their sizes based on high-speed video. The presented problem can be solved by using the instance segmentation approach based on a convolutional neural network. In the presented work Mask R-CNN network architecture was used for estimation of the local boiling characteristics.

Analysis of process efficiency in laser fusion cutting and some single- and multi-objective optimization aspects

2021 ◽  
pp. 095440892110627
Author(s):  
Miloš Madić ◽  
Mohamed H Gadallah ◽  
Dušan Petković
Keyword(s):  
Laser Power ◽  
Laser Cutting ◽  
Optimization Problem ◽  
Removal Rate ◽  
Cutting Speed ◽  
Process Efficiency ◽  
Laser Fusion ◽  
Cut Quality ◽  
Dross Formation ◽  
Laser Fusion Cutting

For an efficient use of laser cutting technology, it is of great importance to analyze the impact of process parameters on different performance indicators, such as cut quality criteria, productivity criteria, costs as well as environmental performance criteria (energy and resource efficiency). Having this in mind, this study presents the experimental results of CO2 laser fusion cutting of AISI 304 stainless steel using nitrogen, with the aim of developing a semi-empirical mathematical model for the estimation of process efficiency as an important indicator of the achievable energy transfer efficiency in the cutting process. The model was developed by relating the theoretical power needed to melt the volume per unit time and used laser power, where the change of kerf width was modeled using an empirical power model in terms of laser cutting parameters such as laser power, cutting speed, and focus position. The obtained results indicated the dominant effect of the focus position on the change in process efficiency, followed by the cutting speed and laser power. In addition, in order to maximize process efficiency and simultaneously ensure high cut quality without dross formation, a laser cutting optimization problem with constraints was formulated and solved. Also, a multi-objective optimization problem aimed at simultaneous optimization of process efficiency and material removal rate was formulated and solved, where the determined set of Pareto non-dominated solutions was analyzed by using the entropy method and multi-criteria decision analysis method, that is, the Technique for Order of Preference by Similarity to Ideal Solution. The optimization results revealed that in order to enhance process efficiency and material removal rate, while ensuring high cut quality without dross formation, focusing the laser beam deep into the bulk of material is needed with particular trade-offs between laser power and cutting speed levels at high pressure levels of nitrogen.

scholarly journals Transition from Stable Laser Fusion Cutting Conditions to Incomplete Cutting Analysed with High-speed X-ray Imaging

2020 ◽  
Vol 60 ◽  
pp. 470-480
Author(s):  
Jannik Lind ◽  
Florian Fetzer ◽  
Christian Hagenlocher ◽  
David Blazquez-Sanchez ◽  
Rudolf Weber ◽  
...  
Keyword(s):  
High Speed ◽  
Cutting Conditions ◽  
Laser Fusion ◽  
X Ray ◽  
X Ray Imaging ◽  
Laser Fusion Cutting ◽  
Stable Laser

scholarly journals Inline High Speed Laser Cutting of Band Material

2016 ◽  
Vol 854 ◽  
pp. 237-242
Author(s):  
Andreas Wetzig ◽  
Jan Hauptmann ◽  
Patrick Herwig ◽  
Eckhard Beyer ◽  
Wieland Bundschuh ◽  
...  
Keyword(s):  
Laser Cutting ◽  
High Speed ◽  
Laser Fusion ◽  
Alternative Technique ◽  
Cutting Machine ◽  
Dynamic Form ◽  
The World ◽  
High Dynamic ◽  
Laser Fusion Cutting ◽  
Band Material

Laser cutting is introduced as an alternative technique to manufacture typical metallic punching and bending parts. Assets and drawbacks of high speed laser cutting technologies like Remote Laser Cutting and laser fusion cutting by means of a high dynamic form cutter are discussed. Finally, the concept of the world´s first industrial inline reel to reel laser cutting machine for metal strips is presented.

Optimum Backwashing of Filters with Air Scour: A Review

1993 ◽  
Vol 27 (10) ◽  
pp. 195-211 ◽  
Author(s):  
Appiah Amirtharajah
Keyword(s):  
High Speed ◽  
Computer Hardware ◽  
Cleaning Process ◽  
Water Flows ◽  
High Speed Video ◽  
Water Treatment Plants ◽  
Model Filter ◽  
The Media ◽  
Air Pockets

The problems occurring in the filtration facilities of water treatment plants, such as mudballs and poor initial filtrate quality are associated with the effectiveness of backwashing. Backwashing with water alone to fluidize the media is an inherently weak cleaning process. The effectiveness of backwashing is significantly improved by the use of air scour simultaneously with subfluidization water wash. When air and subfluidization water flowed concurrently through porous media, a condition termed “collapse- pulsing” occurred in which air pockets formed and collapsed within the bed. A theory has been developed that predicted the combinations of air and water flows that caused collapse-pulsing to occur. Model filter systems have shown that the fluid mechanical condition termed “collapse-pulsing” is also the condition of optimum removal of particles from the media grains during backwashing. The theoretical aspects of collapse-pulsing have been confirmed with an experimental filter system having an endoscope, high speed video system with freeze frame capability for visual observations and an XY Coordinator with computer hardware and software which enabled the determination of velocities of filter grains during air scour. Additional studies on optimum removal of particles from media during air scour have also demonstrated that the results may be extended to dual media filters and are valid at the plant scale too.

Research of the Treatment Parameters Effects on the Layer Formation during Wire-Feed Laser-TIG Deposition with Aluminum Alloy

2019 ◽  
Vol 822 ◽  
pp. 496-503
Author(s):  
V.V. Somonov ◽  
I.A. Tsibulskiy ◽  
Nikita G. Kislov ◽  
Alexander A. Lanin
Keyword(s):  
Cross Sections ◽  
Laser Power ◽  
High Speed ◽  
Video Recording ◽  
Experimental Studies ◽  
Metallographic Analysis ◽  
Layer Formation ◽  
Aluminum Wire ◽  
High Speed Video ◽  
Wire Feed

The paper presents the results of an investigation of the influence parameters of laser radiation on the formation of the deposition layer during laser-TIG direct deposition of aluminum wire. Experimental studies have focused on the determination the dependence shape of layer on the laser power, the distance between axis of laser beam and axis of arc, arc parameters. High-speed video recording of the process was carried out. The metallographic analysis of cross-sections of the samples was performed.

Experimental Analysis of Altitude Relight Under Realistic Conditions Using Laser and High-Speed Video Techniques

2010 ◽  
Author(s):  
T. Mosbach ◽  
R. Sadanandan ◽  
W. Meier ◽  
R. Eggels
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Frame Rate ◽  
Research Centre ◽  
Oh Radicals ◽  
Fuel Injector ◽  
Flow Rates ◽  
Flame Kernel ◽  
High Speed Video ◽  
Mass Flow Rates

The altitude relight performance of a lean fuel injector and combustor was investigated at the altitude relight test rig at the Rolls-Royce Strategic Research Centre (SRC) in Derby. The studies were performed for different mass flow rates of air and kerosene, a combustor temperature and pressure of 278 K and 0.5 bar, respectively. Good optical access to the combustion chamber enabled the application of optical and laser measuring techniques. High-speed video imaging in the UV and visible wavelength range at a frame rate of 3.5 kHz was used to visualize the temporal development of the flame kernel. The observed differences between the UV and visible flame emissions demonstrate the different origins of the luminosity, i.e. OH* chemiluminescence and soot radiation. Further, laser-induced fluorescence of kerosene and OH radicals was applied at a frame rate of 5 Hz to visualize the fuel distribution and regions of hot and reacting mixtures. For two exemplary flames with different mass flow rates and fuel-to-air ratios, the steady burning flames after successful ignition are characterized in this paper by the distributions of kerosene, OH*, OH and soot luminosity. An example of the flame kernel development for a successful ignition is given by an image sequence from a high-speed video recording of the chemiluminescence. The importance of the upstream movement of the flame kernel as a condition preceding successful flame stabilization is identified.

Sign in / Sign up

Export Citation Format

Share Document