Study on Measurement of Melting Process of Molten Pool Formed by Laser Scanning Mirror

The profile and temperature distribution of laser molten pool are mainly factors which have directly effect on quality of laser processing (laser melting and laser cladding). It is very necessary to study measurement method of melting process in laser molten poo1 on-line, for improving processing design and inspecting laser processing quality. A system of dynamic process measurement for laser molten pool was developed. The melting process of laser scanning molten pool formed by high power CO2 Laser was measured. Its temperature distribution was analyzed by special analysis software. It was shown that a section of integrated molten pool would come into being in the middle of the laser scanning line spot after a period of scanning time, and then the molten pool got increased in length with the time, and a little increased in width at the same time, the result was consistent with that of computer numerical simulation. Compared with laser focusing spot, laser scanning spot was more uniform in temperature distribution, that could be propitious to improve the quality of laser processing.

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Comparative Research on the Quality of Micro Hole in Superalloy GH2135 and Stainless Steel 420J1 by Laser Processing

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.703.27 ◽

2016 ◽

Vol 703 ◽

pp. 27-33

Author(s):

Liang Wang ◽

Nai Fei Ren ◽

Yun Long Wang ◽

Lin Zhong Zhu

Keyword(s):

Stainless Steel ◽

Pulse Energy ◽

Laser Processing ◽

Pulse Width ◽

Laser Scanning ◽

Short Pulse ◽

Test Method ◽

Repetition Frequency ◽

Orifice Diameter

Both superalloy GH2135 and stainless steel 420J1 were used as test materials to be processed by LASERTEC 80 PowerDrill three-dimensional solid laser processing center. The microstructure of the hole was investigated by super depth of field microscope and laser scanning microscope. The front and back orifice diameter, orifice deposits and thermal effect of accumulation zone were studied. The single factor test method was used to study the influence of pulse energy, pulse width and repetition frequency on the quality of micro holes. The results showed that the front and back diameter of the holes all increase with the increase of pulse energy from 0.4J-3.9J. And the front and back aperture are increase with the increase of pulse width from 0.9ms-1.9ms. Meanwhile, the variation of the aperture and pore taper is more noticeable with the repetition frequency changed from 10Hz-60Hz. The results revealed that pulse energy is one of the biggest influence factors, large pulse energy can lead to small hole taper within a certain range, and short pulse width can reduce orifice debris and splash. Both the recast layer and microcrack were existed in the two kinds of metal materials. The quality of holes drilling in GH2135 is better than 420J1.

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The Effect of Spot Size Combination Mode on Ablation Morphology of Aluminum Alloy by Millisecond-Nanosecond Combined-Pulse Laser

Materials ◽

10.3390/ma11081419 ◽

2018 ◽

Vol 11 (8) ◽

pp. 1419 ◽

Cited By ~ 7

Author(s):

Bo-Shi Yuan ◽

Ye Zhang ◽

Wei Zhang ◽

Yuan Dong ◽

Guang-Yong Jin

Keyword(s):

Aluminum Alloy ◽

Laser Processing ◽

Molten Pool ◽

Physical Mechanism ◽

Spot Size ◽

Laser Spot ◽

Nanosecond Laser ◽

Combination Mode ◽

First Time

Ablation morphology affects the quality of laser processing. Therefore, the control of ablation morphology is very important. The influence of spot size combination mode on the ablation morphology of aluminum alloy is studied for the first time. Experimental results show that when the nanosecond laser spot is larger, the ablation morphology looks like a bowl-shape, and there is little solidification near the edge. When the nanosecond laser spot is smaller, the shape of the ablation morphology is similar to a hole, and the protuberance is formed near the edge of the cavity. Through the analysis and simulation of the physical model, the physical mechanism, which describes the influence of the spot size combination mode on the molten pool, is discussed. The research results of this paper have important guiding significance for the control of laser processing effect.

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Physical and Numerical Simulation of Flow and Temperature in Molten Pool during Strip Casting Process

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.1545 ◽

2010 ◽

Vol 654-656 ◽

pp. 1545-1548 ◽

Cited By ~ 2

Author(s):

San Bing Ren ◽

Jun Fei Fan ◽

Yan Yu ◽

Yuan Fang

Keyword(s):

Surface Wave ◽

Temperature Distribution ◽

Molten Pool ◽

Casting Process ◽

Strip Casting ◽

Process Stability ◽

Large Wave ◽

Set Up ◽

Quality Of Products

In strip casting process, surface wave and temperature distribution in the molten pool directly affect the process stability and the quality of products. In this paper, physical model and numerical model have been set up and simulated. It has been found that in the corner of the molten pool there is a large wave amplitude on the surface. However, in the middle of molten pool the surface wave is low. The temperature distribution of molten pool showed that the present feeding device need to be optimized.

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Modeling the hardness of the titanium alloy subjected to laser processing

MATEC Web of Conferences ◽

10.1051/matecconf/202032903020 ◽

2020 ◽

Vol 329 ◽

pp. 03020

Author(s):

Vladimir Gusev ◽

Valentin Morozov ◽

Dmitry Gavrilov

Keyword(s):

Titanium Alloy ◽

Surface Layer ◽

Laser Processing ◽

Factor Model ◽

Radiation Power ◽

Treatment Mode ◽

Manufacturing Enterprises ◽

Laser Equipment ◽

Laser Focusing

The article considers the influence of the radiation power W, the longitudinal feed Spr of the laser beam and the distance L from the protective glass of the laser focusing head to the workpiece on the hardness Hv of the titanium alloy TiTaN. A multi-factor model is established that relates the surface layer hardness to the input factors of laser processing and allows you to quickly assign a laser treatment mode and to control it in order to improve the quality of the processed layer. The power W has the greatest effect on the hardness of the surface layer. With increasing W, the hardness increases. Increasing the feed Spr leads to a decrease in the Hv parameter. The effect of the distance L is similar to the radiation power, but the degree of influence of L is more than half as small as W. The developed method of operational assignment of the laser processing mode allows to reduce the auxiliary time for performing the technological operation. The research results are relevant for manufacturing enterprises that implement laser processing processes, as well as for design organizations that develop modern laser equipment.

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Automatic buffer capacity based sensor for effluent quality monitoring

Water Science & Technology ◽

10.2166/wst.1996.0008 ◽

1996 ◽

Vol 33 (1) ◽

pp. 81-87

Author(s):

L. Van Vooren ◽

P. Willems ◽

J. P. Ottoy ◽

G. C. Vansteenkiste ◽

W. Verstraete

Keyword(s):

Wastewater Treatment ◽

Buffer Capacity ◽

Wastewater Treatment Plants ◽

Data Interpretation ◽

Full Scale ◽

Quality Monitoring ◽

Effluent Quality ◽

Capacity Curves ◽

On Line

The use of an automatic on-line titration unit for monitoring the effluent quality of wastewater plants is presented. Buffer capacity curves of different effluent types were studied and validation results are presented for both domestic and industrial full-scale wastewater treatment plants. Ammonium and ortho-phosphate monitoring of the effluent were established by using a simple titration device, connected to a data-interpretation unit. The use of this sensor as the activator of an effluent quality proportional sampler is discussed.

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Enumeration of Cryptosporidium oocysts from surface water concentrates by laser-scanning cytometry

Water Science & Technology ◽

10.2166/wst.2000.0133 ◽

2000 ◽

Vol 41 (7) ◽

pp. 197-202 ◽

Cited By ~ 6

Author(s):

F. Zanelli ◽

B. Compagnon ◽

J. C. Joret ◽

M. R. de Roubin

Keyword(s):

Surface Water ◽

Water Samples ◽

Laser Scanning ◽

Immunomagnetic Separation ◽

Entire Surface ◽

Cryptosporidium Oocysts ◽

Different Types ◽

Laser Scanning Cytometry ◽

Direct Microscopic Observation

The utilization of the ChemScan® RDI was tested for different types of water concentrates. Concentrates were prepared by cartridge filtration or flocculation, and analysed either without purification, or after Immunomagnetic separation (IMS) or flotation on percoll-sucrose gradients. Theenumeration of the oocysts was subsequently performed using the ChemScan® RDI Cryptosporidium application. Enumeration by direct microscopic observation of the entire surface of the membrane was carried out as a control, and recoveries were calculated as a ratio between the ChemScan® RDI result and the result obtained with direct microscopic enumeration. The Chemscan enumeration technique proved reliable, with recoveries yielding close to 100% in most cases (average 125%, range from 86 to 467%) for all the concentration/purification techniques tested. The quality of the antibodies was shown to be critical, with antibodies from some suppliers yielding recoveries a low as 10% in some cases. This difficulty could, however, be overcome by the utilization of the antibody provided by Chemunex. These data conclusively prove that laser scanning cytometry, which greatly facilitates the microscopic enumeration of Cryptosporidium oocysts from water samples and decreases the time of observation by four to six times, can be successfully applied to water concentrates prepared from a variety of concentration/purification techniques.

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Software suite for determining the tilts of tower-type structures according to terrestrial laser scanning

Geodesy and Cartography ◽

10.22389/0016-7126-2020-961-7-2-7 ◽

2020 ◽

Vol 961 (7) ◽

pp. 2-7

Author(s):

A.V. Zubov ◽

N.N. Eliseeva

Keyword(s):

Laser Scanning ◽

Optimization Problems ◽

Optimization Methods ◽

User Participation ◽

Software Suite ◽

Current State ◽

Visual Basic For Applications ◽

Operational Data ◽

Theoretical Developments

The authors describe a software suite for determining tilt degrees of tower-type structures according to ground laser scanning indication. Defining the tilt of the pipe is carried out with a set of measured data through approximating the sections by circumferences. They are constructed using one of the simplest search engine optimization methods (evolutionary algorithm). Automatic filtering the scan of the current section from distorting data is performed by the method of assessing the quality of models constructed with that of least squares. The software was designed using Visual Basic for Applications. It contains several blocks (subprograms), with each of them performing a specific task. The developed complex enables obtaining operational data on the current state of the object with minimal user participation in the calculation process. The software suite is the result of practical implementing theoretical developments on the possibilities of using search methods at solving optimization problems in geodetic practice.

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Fabrication of Mesh Patterns Using a Selective Laser-Melting Process

Applied Sciences ◽

10.3390/app9091922 ◽

2019 ◽

Vol 9 (9) ◽

pp. 1922 ◽

Cited By ~ 3

Author(s):

Tae Woo Hwang ◽

Young Yun Woo ◽

Sang Wook Han ◽

Young Hoon Moon

Keyword(s):

Selective Laser Melting ◽

Laser Scanning ◽

Dimensional Accuracy ◽

Base Plate ◽

Steel Powder ◽

Melting Process ◽

304 Stainless Steel ◽

Process Conditions ◽

Laser Melting ◽

Metal Mesh

The selective laser-melting (SLM) process can be applied to the additive building of complex metal parts using melting metal powder with laser scanning. A metal mesh is a common type of metal screen consisting of parallel rows and intersecting columns. It is widely used in the agricultural, industrial, transportation, and machine protection sectors. This study investigated the fabrication of parts containing a mesh pattern from the SLM of AISI 304 stainless steel powder. The formation of a mesh pattern has a strong potential to increase the functionality and cost-effectiveness of the SLM process. To fabricate a single-layered thin mesh pattern, laser layering has been conducted on a copper base plate. The high thermal conductivity of copper allows heat to pass through it quickly, and prevents the adhesion of a thin laser-melted layer. The effects of the process conditions such as the laser scan speed and scanning path on the size and dimensional accuracy of the fabricated mesh patterns were characterized. As the analysis results indicate, a part with a mesh pattern was successfully obtained, and the application of the proposed method was shown to be feasible with a high degree of reliability.

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Temperature Distribution and Fluid Flow Modeling of Electron Beam Melting® (EBM)

Volume 7: Fluids and Heat Transfer, Parts A, B, C, and D ◽

10.1115/imece2012-89440 ◽

2012 ◽

Cited By ~ 6

Author(s):

M. Jamshidinia ◽

F. Kong ◽

R. Kovacevic

Keyword(s):

Electron Beam ◽

Fluid Flow ◽

Temperature Distribution ◽

Molten Pool ◽

Electron Beam Melting ◽

Control Volume ◽

Thermal Analyses ◽

Scanning Speed ◽

Flow Modeling ◽

Fluid Flow Modeling

A three-dimensional (3D) numerical model is developed by using control volume method to analyze the effects of the electron beam scanning speed on the temperature distribution and fluid flow of the liquid phase in the electron beam melting® (EBM) of Ti-6Al-4V powder. The numerical calculations are performed by Fluent codes, in which thermal analyses with and without considering fluid flow in the molten pool are compared. A series of experiments are performed with an Electron Beam Melting® machine to verify the numerical accuracy. Compared to thermal analysis without considering convection in the molten pool, a closer numerical prediction of geometrical size of molten pool to the experimental data can be achieved by using thermal and fluid flow modeling. The difference between the melt pool geometry in the two models is due to the consideration of the effects of the outward flow in the fluid flow model caused by surface tension.

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