| 1. |
- Magnusson, Claes, et al.
(författare)
-
Creating tailor-made surfaces with high power CO2-lasers
- 1991
-
Ingår i: Proceedings of the first ASM Heat Treatment and Surface Engineering Conference in Europe. - : Trans Tech Publications Inc.. - 0878496424 ; , s. 443-458
-
Konferensbidrag (refereegranskat)
|
|
| 2. |
- Joshi, Shrikant V., 1960-, et al.
(författare)
-
An Analytical Approach to Plasma Spraying
- 1993
-
Ingår i: Plasma spraying. - New Jersey : World Scientific. - 9810213638 ; , s. 121-137
-
Bokkapitel (refereegranskat)
|
|
| 3. |
- Joshi, Shrikant V., 1960-, et al.
(författare)
-
Plasma spraying of ceramic powders produced by the sol-gel technique
- 1992
-
Ingår i: Metals Materials and Processes. - 0970-423X. ; 4:1, s. 33-42
-
Tidskriftsartikel (refereegranskat)abstract
- The development of plasma-sprayed protective layers to enhance the surface properties of critical engineering components represents one of the most promising achievements of materials technology in recent times. The important aspects associated with plasma spraying of ceramic powders are discussed and the influence of the powder characteristics on the quality of sprayed coatings is highlighted. The advantages of the sol-gel technique for preparing spray grade powders are briefly outlined. The sol-gel synthesis of a Yttria-stabilized-zirconia powder is discussed as a case study. Results of powder characterization studies and evaluation of its plasma sprayed coating are also presented.
|
|
| 4. |
- Sivakumar, R., et al.
(författare)
-
Protective Coatings by Plasma Spraying : A Review
- 1991
-
Ingår i: Transactions of the Indian Ceramic Society. - 0371-750X .- 2165-5456. ; 50:1, s. 1-14
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, the use of plasma-sprayed protective coatings has gained increasing acceptance for prolonging the service life of critical components exposed to aggressive environments during normal operation. This paper is aimed at providing an overview of the current state-of-the-art of the plasma coating technology. It includes a brief discussion of the various important aspects associated with the development of reliable protective coatings as well as their evaluation, and outlines some noteworthy advances made in the field of plasma spray materials and equipment in the past few years. The various factors influencing the coating quality are identified and the wide-ranging utility of plasma-sprayed coatings is also highlighted.
|
|
| 5. |
- Cramér, Margareta, 1926-2014
(författare)
-
Gatubeläggning, en del av stadsmiljön
- 1992
-
Ingår i: Kulturmiljövård. - Stockholm : Riksantikvarieämbetet. - 1100-4800. ; :1-2, s. 72-75
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Den skönhetsupplevelse som en gammal stensatt gata ger är stark. Gatstenarna valdes med omsorg, sorterades och sattes vackert i raka skift eller i mönster - i bågform i en sluttning. Stenbeläggningen var funktionell — den ledde bort regnvatten och den var lätt att reparera. Vilken skillnad i kvalitet jämfört med dagens uthällda asfalt!
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Asnafi, Nader, et al.
(författare)
-
On formability of sheet aluminium
- 1990
-
Ingår i: Sheet metals in forming processes. - Borlänge : Materials Center, HTM. ; , s. 81-91
-
Konferensbidrag (refereegranskat)abstract
- Sheet metal behaves differently for different stress and strain ratios. For instance, the material tolerates less deformation at plane strain compared with uniaxial tension. Hill's yield criteria can be used to describe sheet material's deformation behavior. Hill's original yield criterion for plane stress, assuming that there is no planar anisotropy is given. The equation shows better agreement with experimental results when r > 1 (steel 4010), while there is no agreement with experimental results when r < 1 (Al-5052). Hill proposed, therefore, a new yield criterion, which is given. The value of a can be determined by comparing the experimental work-hardening characteristics for uniaxial tension and balanced biaxial tension; 1 < = a < = 2. For soft Al, having an average r-value of 0.723, the value of a has been found to be 1.8. The parameter a has its greatest effect at balanced biaxial tension. Graphs
|
|
| 9. |
- Borgström, Robert
(författare)
-
An automatic tool changer for laser machining centers
- 1993
-
Ingår i: Machine vision applications, architectures, and systems integration II : 7 - 9 September 1993, Boston, Massachusetts ; proceedings / SPIE, The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering. - 0819413291 ; , s. 336-342
-
Konferensbidrag (refereegranskat)abstract
- In order to improve flexibility when changing between different laser processing workheads the author has developed an automatic tool changer for laser machining centres. This tool system was designed for large multi axis machines such as gantries suitable for three-dimensional processing, but can also be used for other types of laser operations like robots for example. The system also offers the possibility to combine laser processing with deburring and milling on the same machine
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Broitman, Esteban, 1958-, et al.
(författare)
-
Thin Film Temperature Sensors (Sensores de Temperatura de Película Delgada)
- 1990
-
Ingår i: Anales AFA. - Buenos Aires, Argentina : Asociacion Fisica Argentina. ; 1:1, s. 336-338
-
Tidskriftsartikel (refereegranskat)abstract
- Ni thin films of 1800 Å thick were deposited by ion-plating and designed by photolithography to be used as temperature sensors. The resistive paths were finished with contact Cu welding terminals. After being coated with a protective layer of SiOx, they were subjected to heat stabilization treatments. Small, stable and accurate sensors were obtained.
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
- Duftschmid, K., et al.
(författare)
-
Strahlenbelastung durch UV Emission beim Laserschweissen
- 1991
-
Ingår i: Strahlen - Felder - Ströme : Schlußbericht = Radiation - fields - currents = Rayonnements - champs - courants électriques = Radiaciones - campos - corrientes. - Köln : IVSS Sektion Elektrizität. - 9284300444
-
Konferensbidrag (refereegranskat)
|
|
| 16. |
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
- Flinkfeldt, Jan, et al.
(författare)
-
Laser cladding in pre-made grooves : guide-lines for groove design
- 1994
-
Ingår i: ASM Heat Treatment and Surface Engineering Conference II. - : Trans Tech Publications Inc.. ; , s. 423-428
-
Konferensbidrag (refereegranskat)abstract
- Post machining of treated components after laser cladding are necessary in most cases. Depending on the quality of the chosen material this job could be laborious and time consuming. By preparing grooves of a certain design on the work piece before laser cladding, the excess material to be removed can be minimized and post machining operations facilitated. The paper describes experimental works with laser cladding in pre-made grooves on cast iron specimens to investigate the influence of special groove design on the cladding results. The results are discussed in terms of macro surface roughness, efficient layer thickness, residual stress in the cladded layer and base material intermixing in the cladding. The results indicate that laser cladding in grooves is a way to reduce cladding material consumption and to increase the coating rate.
|
|
| 20. |
- Fllinkfeldt, Jan
(författare)
-
Laserimprenering
- 1990
-
Rapport (övrigt vetenskapligt/konstnärligt)
|
|
| 21. |
|
|
| 22. |
- Ivarson, Anders, et al.
(författare)
-
Laser cutting of steels : analysis of the particles ejected during cutting
- 1992
-
Ingår i: Welding in the World. - 0043-2288 .- 1878-6669. ; 30:5-6, s. 116-125
-
Tidskriftsartikel (refereegranskat)abstract
- The particles ejected during the CO sub 2 laser cutting of mild and stainless steel were examined by electron microscopy, energy dispersive X-ray analysis and optical microscopy. The material leaves the cut zone as partially oxidized droplets which range in size from 50-500 mu m in diameter. When cutting mild steel approx 50% of the Fe is converted to FeO during the cutting process, whereas for stainless steel approx 30% of the Fe is oxidized to Fe sub 2 O sub 3 . The mild steel particles were found to exist in five distinct oxidation stages whereas the stainless steel particles fell into four groups containing not only Fe sub 2 O sub 3 but also Cr sub 2 O sub 3 and NiO.
|
|
| 23. |
- Ivarson, Anders, et al.
(författare)
-
Optimisation of the laser cutting process for thin section stainless steels
- 1992
-
Ingår i: Proceedings of the laser materials processing symposium. - Orlando, Fla : Laser institute of America. - 9780912035451 ; , s. 211-220
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the results of an experimental program investigating the effects of using a pulsed laser for laser-oxygen cutting of thin section stainless steels. It was discovered that if the pulse conditions are optimised, the maximum cutting speed for a set average laser power could be increased by up to 15%. This increase in cutting speed was made possible by a change in the material removal mechanism in the cut zone. The steady state melting-oxidation-ejection process was replaced by a periodic expulsion of melt as a result of small 'explosions' caused by the spike at the beginning of each laser pulse
|
|
| 24. |
- Ivarson, Anders, et al.
(författare)
-
Oxidation dynamics of laser cutting of mild steel and the generation of striations on the cut edge
- 1994
-
Ingår i: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 40:3-4, s. 359-374
-
Tidskriftsartikel (refereegranskat)abstract
- Over the past two decades CO2 laser cutting has grown from an obscure laboratory technique into an important branch of manufacturing engineering. The most commonly cut materials are steels and a great deal of industrial and scientific research has been carried out on the laser-material interactions that generate a cut. This paper concentrates on the phenomena which give rise to a cyclic cutting event when a CO2 laser in conjunction with an oxygen jet is used to cut mild steel. The nature of the cut edge striation produced by the cyclic oxidation reaction is explained thoroughly and a possible oxidation cycle is postulated. It is demonstrated that the key to understanding the cyclic nature of the cutting event is the self-limiting nature of the oxidation of the steel in the cut zone
|
|
| 25. |
- Ivarson, Anders, et al.
(författare)
-
Role of oxidation in laser cutting stainless and mild steel
- 1991
-
Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 3:3, s. 41-45
-
Tidskriftsartikel (refereegranskat)abstract
- This paper gives the results of a detailed examination of the particles ejected from the cut zone during CO2 laser cutting of mild and stainless steels. Cuts were carried out over a range of material thickness at the optimum speed for each at a laser power of 900 Watts. Particles ejected from the cut zone were collected and analyzed to establish their chemical and physical characteristics. Analysis techniques included Scanning Electron Microscopy, wet chemical analysis, optical microscopy, metallography and particle sizing. The results from this extensive analysis have enabled the authors to estimate the heat generated by the oxidation process during cutting of both mild and stainless steels.
|
|
| 26. |
- Kaplan, Alexander
(författare)
-
A model of deep penetration laser welding based on calculation of the keyhole profile
- 1994
-
Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 27:8, s. 1805-1814
-
Tidskriftsartikel (refereegranskat)abstract
- A model describing the process of deep-penetration laser welding has been developed by calculating the keyhole profile using a point-by-point determination of the energy balance at the keyhole wall. A formula for heat conduction was derived from the model of a moving line source of heat. The various absorption mechanisms were modelled. The corresponding absorbed power transferred to the keyhole wall balances the conduction losses, which yields the local inclination of the wall. The thermodynamics and the flow of metal vapour inside the keyhole have been calculated. Accordingly, beam damping due to the plasma plume above the workpiece and the mean plasma absorption coefficient in the keyhole could be estimated. The keyhole profile tends to a geometry that distributes the major part of the beam to the front wall owing to higher conduction losses at the upstream side. The reasons for decreasing energy absorption with increasing welding speed are discussed.
|
|
| 27. |
- Kaplan, Alexander
(författare)
-
Characterization of laser-induced plasma
- 1992
-
Ingår i: Laser in der Technik. - Berlin : Encyclopedia of Global Archaeology/Springer Verlag. - 3540552472 ; , s. 459-463
-
Konferensbidrag (refereegranskat)
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
|
|
| 32. |
- Kaplan, Alexander, et al.
(författare)
-
Simplified model of deep penetration laser welding
- 1992
-
Ingår i: Laser in der Technik. - Berlin : Encyclopedia of Global Archaeology/Springer Verlag. - 3540552472 ; , s. 464-467
-
Konferensbidrag (refereegranskat)
|
|
| 33. |
- Kaplan, Alexander
(författare)
-
The method of finite differences
- 1992
-
Ingår i: Proceedings on modelling of laser material processing.
-
Konferensbidrag (refereegranskat)
|
|
| 34. |
- Legge, David
(författare)
-
Integration of design, inspection and quality management systems
- 1994
-
Ingår i: Proceedings. - Croydon : Automotive automation. - 0947719687 ; , s. 421-427
-
Konferensbidrag (refereegranskat)abstract
- This paper discusses the integration of design, inspection and quality management systems, and in particular the standard for the exchange of product model data (STEP) and the proposed STEP application protocol (AP) for inspection process planning (AP219). Relatively little progress has so far been made towards development of this AP. The need for a concerted industry led initiative to adopt and continue the work completed to date is suggested. The goal of such a consortium would be to develop and promote the use of AP219 and software tools to support its adoption and implementation
|
|
| 35. |
- Linden, G.
(författare)
-
Laser cutting of low carbon steels and stainless steels
- 1993
-
Ingår i: Svetsen. - 0039-7091. ; :Special issue 2E, s. 31-33
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Among the thermal cutting methods, laser cutting has been in industrial use for a fairly short period. The number of installations has increased considerably during recent years. CO sub 2 -lasers are most common, especially for work-shops making constructions in sheet and plate material, i.e. low-carbon and stainless steels. The assist gases play a considerable role in cutting both for the productivity and for the quality of the cut. The cutting parameters and the pressure and flow rate of the assist gas need careful attention to optimize the laser cutting.
|
|
| 36. |
- Magnusson, Claes, et al.
(författare)
-
Laser workstation for computer-integrated manufacturing
- 1992
-
Ingår i: Robotics and Computer-Integrated Manufacturing. - 0736-5845 .- 1879-2537. ; 9:4-5, s. 391-393
-
Tidskriftsartikel (refereegranskat)abstract
- The application of laser processing technology is rapidly increasing in manufacturing. The laser manufacturing process has since its introduction been computer controlled. At first, the laser was usually a stand alone machine, but recently the demand for its integration with other manufacturing equipment has been stressed. In most respects a laser workstation uses the same interfaces as any other manufacturing equipment. This paper covers some of the integration problems to be solved that are of specific importance for laser workstations.
|
|
| 37. |
- Magnusson, Claes, et al.
(författare)
-
Mathematical modeling of V-die bending process
- 1990
-
Ingår i: Sheet metals in forming processes. - Borlänge : Materials Center, HTM. ; , s. 363-370
-
Konferensbidrag (refereegranskat)abstract
- V-die bending is a non-steady state forming process, in which bending moment varies during forming; stress--strain distribution differs in different cross-sections of a bend. By assuming that an isotropic-hardening von Mises material undergoes plane bending, the moment of internal stresses is expressed as a function of the curvature of the bend, sheet thickness and properties of the material. With the constitutive equations given, one can calculate the configuration of a sheet metal in bending and predict its elastic springback on removing load. The theoretical results have been compared to the experimental data, and good agreement has been found. Materials were: DRQ 1147, DOCOL 220, DOCOL 260, and SIS 2322. Graphs. 10 ref.--AA
|
|
| 38. |
- Magnusson, Claes, et al.
(författare)
-
Superplastic forming of sheet metal
- 1990
-
Ingår i: Sheet metals in forming processes. - Borlänge : Materials Center, HTM. ; , s. 247-254
-
Konferensbidrag (refereegranskat)abstract
- Superplastic forming of sheet metal enables forming of complicated details in one step. The forming is done at very low strain rates, making the process slow and cycle times very long. By shortening the cycle time, it should be possible to decrease the unit cost of production and, as a result, superplastic forming would be a highly competitive forming method for new areas of application. A number of methods to shorten the cycle time are presented. Materials considered were Al 7475, Supral 100, and Cr--Ni steel Avesta 223 FAL.
|
|
| 39. |
- Meijer, J., et al.
(författare)
-
Phase transformations by high-intensity sub-microsecond laser pulses.
- 1992
-
Ingår i: Proceedings of the laser materials processing symposium, ICALEO '92. - Orlando, Fla : Laser institute of America. - 0912035498 ; , s. 228-236
-
Konferensbidrag (refereegranskat)abstract
- In certain alloys, the 'laser shocking' causes work hardening, an increase in dislocation density and phase transformations. Of the materials tested, and austenitic Hadfield manganese-alloyed steel target was found to have the strongest tendency for a martensitic phase transformation. In contrast with conventional transformation hardening, there is no tempering in the case of repeated application. Whilst most material is vaporized, some surface melting will occur. The rate of re-solidification of the molten material is such that an almost completely amorphous structure results. The martensitic transformation has been confirmed by using optical, scanning and transmission electron microscopy, OM, SEM and TEM/STEM. Two different lasers, a Q-switched Ruby and a Q-switched Nd:YAG were used for the experiments. Calculations of impact/momentum, peak pressure and peak temperature were performed using the finite difference method. The model used for simulating the process has been proved to be useful in understanding the transformation mechanism.
|
|
| 40. |
|
|
| 41. |
- Nilsson, Klas, et al.
(författare)
-
A novel method of joining thin tubes
- 1991
-
Ingår i: EUROJOIN 1. - : Institut de Soudure. ; , s. 253-261
-
Konferensbidrag (refereegranskat)abstract
- Radiator tubing formed from brass strip, with wall thicknesses from 0.09-0.120 mm (0.0035-0.0047 in.), has been successfully welded at high welding speed using a CO sub 2 laser. A fully penetrated weld was obtained using welding speeds of > 100 m/min (5.47 ft/s) in production like conditions. The laser used for the welding was a 1700 W, Co sub 2 laser with linear polarisation. A tube with a specially designed "Y" joint was formed in a converted lock seam tube machine. There are several advantages to this new type of "Y" joint, such as higher production rate and the possibility of reducing the thickness of the brass strip by 20-30% when compared to material used in high frequency welding. A large number of parameters were studied including the effects of laser power, welding speed, joint geometry and direction of the laser beam polarisation. Two radiators have been made with solder coated, laser welded tubes. These are currently undergoing mechanical testing. Preliminary results of the testing are favourable.
|
|
| 42. |
|
|
| 43. |
- Nilsson, Klas, et al.
(författare)
-
Laser welding : a method for welding new designed brass tubes
- 1993
-
Ingår i: Working together for a better future. - Croydon : Automotive automation. - 0947719598
-
Konferensbidrag (refereegranskat)abstract
- In this work, two different tube designs for radiators have been laser welded. In the first phase of the project, a single tube was welded. In a second phase, a special design twin tube was welded. Both tube types had a V-joint, which made it possible to laser weld with high speed. The single tube was formed in a converted lock seam tube machine and the twin tube in a new, for this purpose, special designed tube machine. Both forming machines were integrated with a 5-axis laser work station. In the first phase of the project, a more precise joint geometry was found out, which resulted in the new twin tube design. The second phase with the new tube machine has recently started, and will optimize the welding results from the first phase of the project. All welding experiments have been done on brass (CuZn30). This material is normally used for automobile radiators.
|
|
| 44. |
- Nilsson, Klas, et al.
(författare)
-
Laser welding of thin brass tube
- 1993
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Experiments on longitudinally laser welding thin brass tube for radiators were carried out in a tube forming machine in a recently installed laser workstation. A CO2 laser with a circular polarised laser beam was used. The influences of laser power, welding speed, shielding gas (He, Ar, N2), position of the welding point and angle of incidence of the laser beam were determined. Brass strips of 0.12 mm and 0.94 mm thickness were welded. Some limited trials were also carried out on thin copper strip (0.12 mm thickness). Practical considerations in equipment operation are discussed. Process economics and benefits are considered and compared with soldering and HF welding
|
|
| 45. |
- Nilsson, Klas
(författare)
-
Laser welding of thin brass tubes
- 1992
-
Ingår i: Tube International. - 0263-6794. ; 11:48, s. 171-174
-
Tidskriftsartikel (refereegranskat)abstract
- Radiator tubing formed from brass strip, with wall thicknesses from 0.09-0.12 mm, has been successfully welded at high welding speed using a CO sub 2 laser. A fully penetrated weld was obtained using welding speeds of > 100 m/min in production-like conditions. The laser used for welding was a 1700 W, CO sub 2 laser with linear polarisation. A tube with a specially designed "Y" joint was formed in a modified lock-seam tube machine. There are several advantages to this new type of "Y" joint, such as higher production rate and the possibility to reduce the thickness of the brass strip by 20-30% when compared with material used in high-frequency welding. A large number of parameters were studied including the effects of laser power, welding speed, joint geometry and direction of the laser beam polarisation. Two radiators have been made with solder-coated, laser-welded tubes. These are currently undergoing mechanical testing. Preliminary results of testing are favourable.
|
|
| 46. |
|
|
| 47. |
|
|
| 48. |
- Ohlsson, L., et al.
(författare)
-
Comparison between abrasive water jet cutting and laser cutting
- 1991
-
Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 3:3, s. 46-50
-
Tidskriftsartikel (refereegranskat)abstract
- This paper is intended to demonstrate the advantages and disadvantages of laser profiling techniques as compared with the Abrasive Water Jet (AWJ). The growth of AWJ as a cutting tool has provided engineers with a new profiling technique which often offers great technical and commercial advantages over more traditional methods. However, AWJ cutting is not the best solution to all profiling problems. There are a number of techniques which compete with or complement the process and the optimum profiling method can be difficult to identify. The following paper serves as a general guide-line comparing two competitive cutting methods (CO2 laser cutting and Nd: YAG laser cutting) with AWJ cutting. The subject of cutting covers a great many more processes than can be reviewed in one article but the techniques to be discussed were chosen because they all involve profiling using an axially symmetric energy beam of some sort
|
|
| 49. |
- Ohlsson, L., et al.
(författare)
-
Mechanisms of striation formation in abrasive water jet cutting
- 1994
-
Ingår i: 12th International Conference on Jet Cutting Technology. - London : Institution of Mechanical Engineers. - 0852989253 ; , s. 151-164
-
Konferensbidrag (refereegranskat)abstract
- In an experimental program investigating cut edge striation generation during AWJ (abrasive water jet) cutting, mild steel and aluminium alloy samples have been cut with a range of process parameters and the resulting cut edge striation carefully analysed to develop a phenomenological model of striation generation based on variations in the geometry of the cut front. The existence of a range of moving steps on the cut front has been confirmed by the use of high speed video recording of the cut front when cutting transparent materials.
|
|
| 50. |
|
|
