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Towards full Automation of Robotized Laser Metal-wire Deposition
University West, Department of Engineering Science.
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Metal wire deposition by means of robotized laser welding offers great saving potentials, i.e. reduced costs and reduced lead times, in many different applications, such as fabrication of complex components, repair or modification of high-value components, rapid prototyping and low volume production, especially if the process can be automated. Metal deposition is a layered manufacturing technique that builds metal structures by melting metal wire into beads which are deposited side by side and layer upon layer. This thesis presents a system for on-line monitoring and control of robotized laser metal wire deposition (RLMwD). The task is to ensure a stable deposition process with correct geometrical profile of the resulting geometry and sound metallurgical properties. Issues regarding sensor calibration, system identification and control design are discussed. The suggested controller maintains a constant bead height and width throughout the deposition process. It is evaluated through real experiments, however, limited to straight line deposition experiments. Solutions towards a more general controller, i.e. one that can handle different deposition paths, are suggested.

A method is also proposed on how an operator can use different sensor information for process understanding, process development and for manual on-line control. The strategies are evaluated through different deposition tasks and considered materials are tool steel and Ti-6Al-4V. The developed monitoring system enables an operator to control the process at a safe distance from the hazardous laser beam.

The results obtained in this work indicate promising steps towards full automation of the RLMwD process, i.e. without human intervention and for arbitrary deposition paths.

Place, publisher, year, edition, pages
2009. , 82 p.
Series
Technical Report, ISSN 1403-266X ; R002/2009
Keyword [en]
Laser metal wire deposition, process control, process development, optical sensors, robotic weld equipment
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
URN: urn:nbn:se:hv:diva-2148OAI: oai:DiVA.org:hv-2148DiVA: diva2:287573
Presentation
2009-03-13, C120, Högskolan Väst, Trollhättan, 10:15 (English)
Opponent
Supervisors
Projects
RMS
Available from: 2010-03-03 Created: 2010-01-19 Last updated: 2010-04-22Bibliographically approved
List of papers
1. Control Design for Automation of Robotized Laser Metal-Wire Deposition
Open this publication in new window or tab >>Control Design for Automation of Robotized Laser Metal-Wire Deposition
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2008 (English)In: Proceedings of the 17th IFAC World Congress, International Federation of Automatic Control , 2008, 14785-14791 p.Conference paper, (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
International Federation of Automatic Control, 2008
Series
IFAC PapersOnLine, ISSN 1474-6670 ; Vol 17
Keyword
Multi sensor systems, Robotics technology
National Category
Metallurgy and Metallic Materials
Research subject
ENGINEERING, Mechatronics; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-2248 (URN)10.3182/20080706-5-KR-1001.02503 (DOI)
Conference
17th IFAC World Congress, IFAC’08, Seoul Korea, July 6-11, 2008
Available from: 2010-03-03 Created: 2010-03-03 Last updated: 2016-02-09Bibliographically approved
2. Visual feed-back for operator interaction in robotized laser metal deposition
Open this publication in new window or tab >>Visual feed-back for operator interaction in robotized laser metal deposition
2008 (English)In: Proceedings of the 22nd International Conference on Surface Modification Technologies SMT22: Held at University West, Trollhättan, Sweden September 22-24, 2008 / [ed] T.S. Sudarshan & Per Nylen, 2008, 297-304 p.Conference paper, (Other academic)
Series
Surface Modification Technologies, 22
National Category
Metallurgy and Metallic Materials
Research subject
ENGINEERING, Mechatronics; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-2249 (URN)978-0-9817065-1-1 (ISBN)
Conference
Surface Modification Technologies SMT22
Available from: 2010-03-03 Created: 2010-03-03 Last updated: 2016-02-09Bibliographically approved
3. Increased stability in laser metal wire deposition through feedback from optical measurements
Open this publication in new window or tab >>Increased stability in laser metal wire deposition through feedback from optical measurements
2010 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 48, no 4, 478-485 p.Article in journal (Refereed) Published
Abstract [en]

Robotized laser metal-wire deposition is a fairly new technique being developed at University West in cooperation with Swedish industry for solid freeform fabrication of fully densed metal structures. It is developed around a standard welding cell and uses robotized fiber laser welding and wire filler material together with a layered manufacturing method to create metal structures. In this work a monitoring system, comprising two cameras and a projected laser line, is developed for on-line control of the deposition process. The controller is a combination of a PI-controller for the bead width and a feed-forward compensator for the bead height. It is evaluated through deposition of single-bead walls, and the results show that the process stability is improved when the proposed controller is used.

Keyword
Laser deposition, metal wire, machine vision, process control, robotic welding equipment
National Category
Control Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-2082 (URN)10.1016/j.optlaseng.2009.08.012 (DOI)000275074900011 ()
Projects
RMS
Available from: 2009-12-28 Created: 2009-12-28 Last updated: 2016-02-09Bibliographically approved

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