| 1. |
- Heralic, Almir, 1981-, et al.
(författare)
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Automatic in-process control of laser metal-wire deposition based on sensor feedback
- 2011
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Ingår i: 30th Interantional Congress on Applications of Lasers & Electro-Optics, ICALEO 2011. ; , s. 211-220
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Konferensbidrag (refereegranskat)abstract
- This paper describes alasermetaldepositionsystem that isbasedon robotizedlaserwelding andwirefiller material. The system has been found suitable for the manufacture of simple but large shapes with high metallurgical requirements such as bosses or flanges found on aero engine components. Several benefits have been identified with the usage ofwirefiller compared to powderized feedstock, such as betterprocessefficiency, higherdepositionrates, and cleaner working environment. Thewirebaseddepositionprocessis however sensitive to disturbances and thus requires continuous monitoring and adjustments.Inthis work a 3D scanning system is described forautomaticin-processcontrolof thedeposition. The goal is to obtain a flat surface for each deposited layerinorder to ensure stabledeposition. The deviationsinthe layer height are compensated by controlling thewirefeed rate. The system is tested throughdepositionof small cylindrical bosses and the results show that the proposedcontrolapproach is suitable forautomaticdepositionof such structures. The material consideredinthis paper is Ti-6Al-4V deposited on plates of same material. The paper presents the equipment and thecontrolstrategy and discusses practical issues regarding thesensorused.
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| 2. |
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| 3. |
- Ryberg, Anders, 1973-, et al.
(författare)
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Analysis and evaluation of a general camera model
- 2011
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Ingår i: Computer Vision and Image Understanding. - : Elsevier. - 1077-3142 .- 1090-235X. ; 115:11, s. 1503-1515
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Tidskriftsartikel (refereegranskat)abstract
- A versatile General Camera Model, GCM, has been developed, and is described in detail. The model is general in the sense that it can capture both fisheye and conventional as well as catadioptric cameras in a unified framework. The camera model includes efficient handling of non-central cameras as well as compensations for decentring distortion. A novel way of analysing radial distortion functions of camera models leads to a straightforward improvement of conventional models with respect to generality, accuracy and simplicity. Different camera models are experimentally compared for two cameras with conventional and fisheye lenses, and the results show that the overall performance is favourable for the GCM.
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| 4. |
- Sikström, Fredrik, 1971-, et al.
(författare)
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Role of fixture forces on distortion in gas tungsten arc welding - an experimental and modelling approach
- 2011
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture. - : Sage Publications. - 0954-4054 .- 2041-2975. ; 225:B1, s. 140-148
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Tidskriftsartikel (refereegranskat)abstract
- Simulation and experiments show that the fixture clamping force has a significant influence on the structural integrity of a welded workpiece. This understanding is of great importance for the manufacture of aerospace components with tight tolerances in the specifications. The focus in the present study is on the temperature history during welding and residual deformation; its main contribution is a demonstrator designed for evaluation of the influence of fixture clamping forces and validation of the simulation results. The demonstrator concerns a simplified situation considering gas tungsten arc welding of a nickel-based metal plate fixed by a specially designed fixture, where one side of the plate was clamped with different levels of force. The temperature history was measured during the weld sequence and deformation measurements were performed after cooling and release of the workpiece from the fixture. The results from simulation and experimentation showed good agreement. The proposed strategy is industrially competitive and has shown that the looser the fixture clamps, the smaller the residual deformation. Furthermore, the study provides a knowledge base for selection of active fixture concepts in that the fixture clamping force can be determined in advance and possibly also be subject to force control.
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