scholarly journals Influence of mill scale on oxygen laser cutting processes

2021 ◽  
Vol 1135 (1) ◽  
pp. 012008
Author(s):  
Handika Sandra Dewi ◽  
Joerg Volpp ◽  
Jan Frostevarg ◽  
Jukka Siltanen
Keyword(s):  
Laser Cutting ◽  
High Speed ◽  
Imaging System ◽  
Focal Point ◽  
Fibre Laser ◽  
Atmospheric Effects ◽  
High Speed Imaging ◽  
Mill Scale ◽  
Cutting Processes ◽  
Ytterbium Fibre Laser

Abstract Mill scale formed on the surface of hot rolled steels consists of magnetite (Fe3O4), hematite (Fe2O3) and wustite (FeO) layers, which can protect the steels from corrosion and other atmospheric effects. Existence of mill scale on the specimens’ surface has shown to be able to decrease the cut edge quality. Since the mechanism behind influence of mill scale on the laser cutting process is unknown, this work performs direct observation of oxygen laser cutting processes on specimens with and without removed mill scale layers. Oxygen laser cutting processes were carried out using Ytterbium fibre laser 1070 nm along the edge of 20-mm-thick-steel specimens which were attached to a borosilicate glass. Focal point of the laser beam was positioned to be 0.7 mm below the specimens’ surface. A high speed imaging system was arranged to face the glass, recording the cut front and kerf dynamics during cutting processes. It was found that cut front inclination angle increase when the mill scale was removed from the specimens’ surface. This implies that mill scale on the specimens’ surface seem to contribute in increasing the exothermal energy during laser cutting processes.

scholarly journals Experimental study of the dynamic behaviour of High Performance Concrete (HPC) under tensile loading

2018 ◽  
Vol 183 ◽  
pp. 02043 ◽  
Author(s):  
Bratislav Lukić ◽  
Dominique Saletti ◽  
Pascal Forquin
Keyword(s):  
High Speed ◽  
High Performance ◽  
High Performance Concrete ◽  
Imaging System ◽  
Spall Strength ◽  
High Speed Imaging ◽  
Dynamic Tensile Strength ◽  
Full Field ◽  
Local Point ◽  
Measurement Results

This paper presents the measurement results of the dynamic tensile strength of a High Performance Concrete (HPC) obtained using full-field identification method. An ultra-high speed imaging system and the virtual fields method were used to obtain this information. Furthermore the measurement results were compared with the local point-wise measurement to validate the data pressing. The obtained spall strength was found to be consistently 20% lower than the one obtained when the Novikov formula is used.

Nucleate Boiling From Micro-Machined Surfaces

2003 ◽  
Author(s):  
Adrian M. Holland ◽  
Colin P. Garner
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Imaging System ◽  
Laser System ◽  
Ccd Camera ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Frame Rate ◽  
High Speed Imaging ◽  
Machined Surfaces

This paper discusses the production and use of laser-machined surfaces that provide enhanced nucleate boiling and heat transfer characteristics. The surface features of heated plates are known to have a significant effect on nucleate boiling heat transfer and bubble growth dynamics. Nucleate boiling starts from discrete bubbles that form on surface imperfections, such as cavities or scratches. The gas or vapours trapped in these imperfections serve as nuclei for the bubbles. After inception, the bubbles grow to a certain size and depart from the surface. In this work, special heated surfaces were manufactured by laser machining cavities into polished aluminium plates. This was accomplished with a Nd:YAG laser system, which allowed drilling of cavities of a known diameter. The size range of cavities was 20 to 250 micrometers. The resulting nucleate pool boiling was analysed using a novel high-speed imaging system comprising an infrared laser and high resolution CCD camera. This system was operated up to a 2 kHz frame rate and digital image processing allowed bubbles to be analysed statistically in terms of departure diameter, departure frequency, growth rate, shape and velocity. Data was obtained for heat fluxes up to 60 kW.m−2. Bubble measurements were obtained working with water at atmospheric pressure. The surface cavity diameters were selected to control the temperature at which vapour bubbles started to grow on the surface. The selected size and spacing of the cavities was also explored to provide optimal heat transfer.

scholarly journals Low-Cost High-Speed Imaging System for Observing Vocal Fold Vibration in Voice Disorders

ORL ◽  
2012 ◽  
Vol 74 (4) ◽  
pp. 208-210 ◽  
Author(s):  
Kenichi Kaneko ◽  
Koichi Sakaguchi ◽  
Masato Inoue ◽  
Haruo Takahashi
Keyword(s):  
Vocal Fold ◽  
High Speed ◽  
Imaging System ◽  
Low Cost ◽  
Voice Disorders ◽  
High Speed Imaging ◽  
Vocal Fold Vibration

Velocity Measurements Using High-Speed Imaging System for Impact Test

2014 ◽  
Vol 903 ◽  
pp. 187-193 ◽  
Author(s):  
Abdul Aziz Jaafar ◽  
Anwar P.P. Abdul Majeed ◽  
S.M. Sapuan ◽  
Shahnor Basri
Keyword(s):  
High Speed ◽  
Impact Test ◽  
Imaging System ◽  
Velocity Measurements ◽  
Glass Composite ◽  
Free Flight ◽  
High Speed Imaging ◽  
Fibre Glass ◽  
System A ◽  
Kinematic Properties

This paper presents the velocity measurements for an impact test on a laminated fibre-glass composite plate. The free flight kinematic properties of a blunt-nosed cylindrical projectile on the upstream and downstream of a test coupon were measured using a high-speed camera imaging system. A visual geometric detection technique is discussed and it is shown that the uncertainties of velocity measurements are associated with an imposed constraint on the camera viewing area and shutter speed.

Experimental Determination of the Focal Length of a Laser Beam from the Output Nozzle of a Laser Cutting Head

2017 ◽  
Vol 756 ◽  
pp. 71-79
Author(s):  
Martin Lachman ◽  
Jiří Šafka
Keyword(s):  
Laser Beam ◽  
Laser Cutting ◽  
Focal Point ◽  
Focal Length ◽  
Cutting Speed ◽  
Vital Role ◽  
Fibre Laser ◽  
Cutting Head ◽  
Industrial Operations

Laser technologies are considered to be unconventional technologies. Laser cutting is one of the most popular industrial operations that use a laser beam. Fibre lasers are most commonly used for cutting metallic materials. The aim of this paper is to experimentally demonstrate a procedure for determining the focal length of a laser beam from the output of the cutting head of a JK400FL fibre laser. Along with other factors, the correct position of the focal point of a laser beam cutting materials, plays a vital role in the quality of the cut and also in determining the cutting speed. It is possible to use a higher cutting speed of the laser machine, without compromising the quality of the cut.

Visualization of Oil Droplets Distribution in a Rotary Compressor

2019 ◽  
Author(s):  
Puyuan Wu ◽  
Jun Chen ◽  
Paul E. Sojka
Keyword(s):  
Multiphase Flow ◽  
High Speed ◽  
Imaging System ◽  
Discharge Rate ◽  
Current Phase ◽  
Rotary Compressor ◽  
Cfd Analysis ◽  
High Speed Imaging ◽  
Oil Droplets ◽  
Rolling Piston

Abstract A rotary compressor relies on an eccentric rolling piston, which rotates at high speed, to compress gas in the compression chamber. The oil in the rotary compressor is used for lubricating the bearing and sealing the clearance of sliding parts. However, the oil can exhaust from the rotary compressor by the refrigerant flow and reduce the reliability of the compressor as a result. Thus, studying the behavior of oil droplets distribution in a rotary compressor is a major challenge for manufacturers who rely on CFD tools to predict the multiphase flow. By modifying a rotary compressor, the oil behavior inside the cylinder is observed and recorded by a high-speed imaging system. In the current phase, multiple targeted locations, including the space between the bearing housing and the stator, and the space above the stator are measured in different conditions. The number, size, velocity, and morphology of oil droplets are analyzed based on multiple snapshots. The result can assist designers in improving the CFD analysis of compressors and ultimately reducing the oil discharge rate (ODR).

A visible light high-speed imaging system and tomographic reconstruction of plasma emissivity on the J-TEXT tokamak

2019 ◽  
Vol 146 ◽  
pp. 578-581
Author(s):  
Minghui Xia ◽  
Zhipeng Chen ◽  
Huapu Deng ◽  
Jie Yang ◽  
Lizhi Zhu ◽  
...  
Keyword(s):  
Visible Light ◽  
High Speed ◽  
Imaging System ◽  
Tomographic Reconstruction ◽  
High Speed Imaging
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