| 1. |
- Christiansson, Anna-Karin, 1947-, et al.
(författare)
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Automation of a robotised metal deposition system using laser melting of wire
- 2008
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Ingår i: 18th International Conference on<em> </em>Flexible Automation and Intelligent Manufacturing (FAIM 2008). - 9789163327575 ; , s. 122-129
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a system for full automation of free-form-fabrication of fully dense metal structures using robotized laser melting of wire. The structure is built of beads of melted wire laid side by side and layer upon layer governed by synchronized robot motion. By full automation is here meant that the process starts with a product specification of a component, and ends in a geometrically validated dense metal component fulfilling industrial material requirements. Due to the complexity of this flexible manufacturing system, a number of different disciplines are involved. This paper discusses mainly the system design, which includes how off-line programming is used for automatic generation of code and how feedback control is used for on-line adjustment of parameters based on desired building properties. To meet industrial needs, the project is carried out in a close cooperation between research and development activities in academy and industry.
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| 2. |
- Hagqvist, Petter, et al.
(författare)
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Automation of a laser welding system for additive manufacturing
- 2015
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Ingår i: Proceedings of the 2015 IEEE International Conference on Automation Science and Engineering. - : IEEE. - 9781467381826 ; , s. 900-905
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Konferensbidrag (refereegranskat)abstract
- This paper presents the benefits and challenges ofusing a standard robotised laser welding cell for additive manufacturing(AM). Additive manufacturing, sometimes denoted3D-printing or rapid prototyping, has lately met strong interestin several areas of society, and a variety of technologies andmaterials have been in focus. The current paper summarisesautomation efforts for AM of advanced aero engine componentsusing high power laser with welding optics as power source formelting metal wire and using an industrial robot for obtaininga 3-dimensional feature shape. The challenges are related to theprocess itself encountering high and repeated temperatures withmelting and solidification of the metal as the main players. Themajor research solutions discussed in this paper are relatedto automation issues for obtaining a stable process and tohave control of the temperatures and temperature changes thatthe metals encounter during the process. The solutions aresuccessfully implemented in an industrial laser welding cell.
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| 3. |
- Hagqvist, Petter, et al.
(författare)
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Resistance based iterative learning control of additive manufacturing with wire
- 2015
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Ingår i: Mechatronics (Oxford). - : Elsevier BV. - 0957-4158 .- 1873-4006. ; 31, s. 116-123
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents successful feed forward control of additive manufacturing of fully dense metallic components. The study is a refinement of former control solutions of the process, providing more robust and industrially acceptable measurement techniques. The system uses a solid state laser that melts metal wire, which in turn is deposited and solidified to build the desired solid feature on a substrate. The process is inherently subjected to disturbances that might hinder consecutive layers to be deposited appropriately. The control action is a modified wire feed rate depending on the surface of the deposited former layer, in this case measured as a resistance. The resistance of the wire stick-out and the weld pool has shown to give an accurate measure of the process stability, and a solution is proposed on how to measure it. By controlling the wire feed rate based on the resistance measure, the next layer surface can be made more even. A second order iterative learning control algorithm is used for determining the wire feed rate, and the solution is implemented and validated in an industrial setting for building a single bead wall in titanium alloy. A comparison is made between a controlled and an uncontrolled situation when a relevant disturbance is introduced throughout all layers. The controller proves to successfully mitigate these disturbances and maintain stable deposition while the uncontrolled deposition fails.
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| 4. |
- Hagqvist, Petter, 1986, et al.
(författare)
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Resistance measurements for control of laser metal wire deposition
- 2014
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Ingår i: Optics and Lasers in Engineering. - : Elsevier BV. - 0143-8166 .- 1873-0302. ; 54, s. 62-67
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Tidskriftsartikel (refereegranskat)abstract
- A method for controlling robotized laser metal wire deposition on-line by electrical resistance metering is proposed. The concept of measuring the combined resistance of the wire and the weld pool is introduced and evaluated for automatic control purposes. Droplet formation, detachment of the wire from the weld pool and stubbing can be hard to avoid during processing due to the sensitive process and short reaction times needed for making on-line adjustments. The implemented system shows a possible route for automatic control of the process wherein such problems can be avoided automatically. The method proves to successfully adjust the distance between the tool and the workpiece through controlling the robot height position, thus increasing stability of the laser metal wire deposition process. (C) 2013 Elsevier Ltd. All rights reserved.
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| 5. |
- 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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| 6. |
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| 7. |
- Heralic, Almir, 1981-, et al.
(författare)
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Automation of Robotized Laser Metal-Wire Deposition
- 2007
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Ingår i: Proceedings of the ninth IASTED International Conference on Control and Applications. - : ACTA Press. - 9780889866652 ; , s. ID 658-075-
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Konferensbidrag (refereegranskat)
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| 8. |
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| 9. |
- Heralic, Almir, 1981-, et al.
(författare)
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Control Design for Automation of Robotized Laser Metal-Wire Deposition
- 2008
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Ingår i: Proceedings of the 17th IFAC World Congress. - : International Federation of Automatic Control. ; , s. 14785-14791
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper a novel approach towards automation of robotized laser metal-wire deposition (RLMwD) is described. The RLMwD technique is being developed at University West in cooperation with Swedish industry for solid freeform fabrication of fully dense metal structures. The process utilizes robotized fibre laser welding and metal wire filler material, together with a layered manufacturing method, to create metal structures directly from a CAD drawing. The RLMwD process can also be used for repair or modification of existing components. This paper faces the challenge of designing a control system for maintaining stable process variables, such as a constant layer height and a stable component temperature, during the entire manufacturing process. Several problems are identified and discussed in the paper, e.g. the difficulty of obtaining the bead height in the weld pool environment. The case study is a repair application for stamping tools, where worn out trim edges are to be repaired. Issues regarding the control design, system identification, and the practical implementation of this application are discussed.
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| 10. |
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