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Träfflista för sökning "WFRF:(Powell John) ;pers:(Engström Hans)"

Sökning: WFRF:(Powell John) > Engström Hans

  • Resultat 1-6 av 6
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1.
  • Gedda, Hans, et al. (författare)
  • Energy redistribution during CO2 laser cladding
  • 2001
  • Ingår i: Congress proceedings. - Orlando, Fla : Laser institute of America. - 912035730 ; , s. 549-558
  • Konferensbidrag (refereegranskat)abstract
    • This paper examines the factors that effect the efficiency of the CO sub 2 -laser powder cladding process. By theoretical calculation and experimental work it has been possible to identify how much of the original laser energy contributes to the cladding process and how much is lost to the surrounding environment by reflection, radiation, convection etc. Every aspect of energy redistribution has been analysed and quantified and this has lead to a deeper understanding of the process. The paper concludes with a number of suggestions for improving the efficiency of blown powder laser cladding
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2.
  • Gedda, Hans, et al. (författare)
  • Energy redistribution during CO2 laser cladding
  • 2002
  • Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 14:2, s. 78-82
  • Tidskriftsartikel (refereegranskat)abstract
    • This article examines the factors that effect the efficiency of the CO sub 2 -laser powder cladding process. By theoretical calculation and experimental work it has been possible to identify how much of the original laser energy contributes to the cladding process and how much is lost to the surrounding environment by reflection, radiation, convection, etc. Every aspect of energy redistribution has been analyzed and quantified and this has led to a deeper understanding of the process. The article concludes with a number of suggestions for improving the efficiency of blown powder laser cladding.
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3.
  • Li, W-B, et al. (författare)
  • Modeling of the laser cladding process : preheating of the blown powder material
  • 1995
  • Ingår i: Lasers in engineering (Print). - 0898-1507 .- 1029-029X. ; 4:4, s. 329-341
  • Tidskriftsartikel (refereegranskat)abstract
    • Laser cladding is a high precision method of improving the wear and corrosion resistance of metal surfaces. The process gives high quality, porosity free surface layers, with low dilution of the substrate material and with excellent bonding to the substrate. Most frequently metal powder is used as cladding material and there are basically two different methods of application: i) a pre-placed bed of powder on the substrate surface; ii) powder blown into the beam-substrate interaction zone by an inert gas stream, The blown powder cladding process is much more flexible with respect to surface geometries and is therefore the most frequently used method in industry and the subject of this paper. As the blown particles travel through the laser beam on their way to the laser-substrate interaction zone they become heated. This paper gives the results of a theoretical model which investigates the level of pre heating experienced by the particles and the effects of various parameters on this pre heating. The results are important, as the powder particle temperature is expected to be an important parameter in the modelling and control of the cladding process.
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4.
  • Li, W.-B, et al. (författare)
  • Redistribution of the beam power in laser cladding by powder injection
  • 1996
  • Ingår i: Lasers in engineering (Print). - 0898-1507 .- 1029-029X. ; 5:3, s. 175-183
  • Tidskriftsartikel (refereegranskat)abstract
    • In the process of cladding by using blown powder, the laser light passes through the injected powder and is incident on the surface of the substrate. As a result of the presence of the powder cloud there will be a reduction in the laser beam irradiance experienced by the melt pool below it. This effect will be more pronounced where the cloud is at it's deepest. The original laser power density distribution will therefore be altered by passage through the powder stream. The present paper quantitatively describes this phenomenon and suggest some equations by which the redistribution of the power density of the laser beam through the powder cloud can be evaluated. The significance of the redistribution of the laser beam and its possible effect on the temperature in the substrate is also discussed.
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5.
  • Nilsson, Klas, et al. (författare)
  • Fatigue strength of Nd:YAG-laser welded stainless steel lap joints
  • 2001
  • Ingår i: Congress proceedings. - Orlando, Fla : Laser institute of America. - 912035730 ; , s. 419-428
  • Konferensbidrag (refereegranskat)abstract
    • The primary field of application for thin section stainless steels has traditionally been to provide a corrosion resistant surface. More recent applications of these materials have also concentrated on structural applications and there is an increasing demand for data concerning the properties of welds. Laser welding is ideally suited to the joining of thin section stainless steel sheets and this paper presents the results of an investigation into the fatigue properties of such welds. The work investigates the influence of sheet thickness, weld width, porosity and inter-sheet gaps on the fatigue life of the welds. Fatigue tests were carried out on thin section stainless steel lap welds produced by Nd:YAG-laser. Analysis of the fatigue tests results and the fracture surfaces identified sheet thickness and inter sheet gaps as having considerable effect on fatigue life. Weld width has a more moderate influence on fatigue life and weld porosity has a negligible effect at low concentrations.
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6.
  • Powell, John, et al. (författare)
  • Laser cutting stainless steel with dual focus lenses
  • 2000
  • Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 12:6, s. 224-231
  • Tidskriftsartikel (refereegranskat)abstract
    • In this article the performance of a new type of lens is compared with traditional meniscus lenses for CO sub 2 laser cutting of medium ( > 5 mm) section stainless steel. Dual Focus lenses produce two focus spots, one above the other. This type of optic was found to be capable of higher cutting speeds and better quality cuts. A phenomenological model is presented which explains the superior performance of Dual Focus lenses. The model concentrates upon the fact that during high speed cutting of medium section metals, the laser does not irradiate the lower portion of the cut zone. This lower part of the cut is heated by the melt flowing over it, which has been previously heated by the laser. This melt preheating involves narrower kerfs and higher cut speeds if a dual focus lens is used.
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  • Resultat 1-6 av 6
Typ av publikation
tidskriftsartikel (4)
konferensbidrag (2)
Typ av innehåll
refereegranskat (6)
Författare/redaktör
Powell, John (6)
Magnusson, Claes (4)
Li, W-B (4)
Tan, Z (2)
Gedda, Hans (2)
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Wahlström, G. (2)
Nilsson, Klas (1)
Under, J. (1)
Tan, W.K. (1)
Maclennan, P (1)
Rudd, D. (1)
Wykes, C. (1)
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Luleå tekniska universitet (6)
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Engelska (5)
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