Change search
Link to record
Permanent link

Direct link
BETA
Heralic, Almir
Publications (10 of 18) Show all publications
Hagqvist, P., Christiansson, A.-K. & Heralic, A. (2015). Automation of a laser welding system for additive manufacturing. In: Kazuhiro Saitou, Univ. of Michigan (Ed.), Proceedings of the 2015 IEEE International Conference on Automation Science and Engineering: . Paper presented at 11th IEEE International Conference on Automation Science and Engineering, CASE 2015; Elite Park Avenue HotelGothenburg; Sweden; 24 August 2015 through 28 August 2015 (pp. 900-905). IEEE
Open this publication in new window or tab >>Automation of a laser welding system for additive manufacturing
2015 (English)In: Proceedings of the 2015 IEEE International Conference on Automation Science and Engineering / [ed] Kazuhiro Saitou, Univ. of Michigan, IEEE, 2015, p. 900-905Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
IEEE, 2015
Keywords
Additive manufacturing, laser welding
National Category
Control Engineering Aerospace Engineering Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-8015 (URN)10.1109/CoASE.2015.7294213 (DOI)000380453000149 ()2-s2.0-84952778708 (Scopus ID)978-1-4673-8182-6 (ISBN)
Conference
11th IEEE International Conference on Automation Science and Engineering, CASE 2015; Elite Park Avenue HotelGothenburg; Sweden; 24 August 2015 through 28 August 2015
Available from: 2015-08-31 Created: 2015-08-31 Last updated: 2020-03-09Bibliographically approved
Hagqvist, P., Heralic, A., Christiansson, A.-K. & Lennartson, B. (2015). Resistance based iterative learning control of additive manufacturing with wire. Mechatronics (Oxford), 31, 116-123
Open this publication in new window or tab >>Resistance based iterative learning control of additive manufacturing with wire
2015 (English)In: Mechatronics (Oxford), ISSN 0957-4158, E-ISSN 1873-4006, Vol. 31, p. 116-123Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Additive manufacturing, Metal deposition, Automatic control, Resistance, Process measurement, Iterative learning control
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-7429 (URN)10.1016/j.mechatronics.2015.03.008 (DOI)000367772000013 ()
Note

Available online 10 April 2015. Ingår i avhandling

Available from: 2015-03-06 Created: 2015-03-06 Last updated: 2020-04-01Bibliographically approved
Hagqvist, P., Heralic, A., Christiansson, A.-K. & Lennartson, B. (2014). Resistance measurements for control of laser metal wire deposition. Optics and lasers in engineering, 54(March), 62-67
Open this publication in new window or tab >>Resistance measurements for control of laser metal wire deposition
2014 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 54, no March, p. 62-67Article in journal (Refereed) Published
Abstract [en]

A method for controlling robotized laser metal wire deposition online 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.

Keywords
Laser metal wire deposition;Automatic control ;Resistance ; Additive manufacturing
National Category
Robotics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-5610 (URN)10.1016/j.optlaseng.2013.10.010 (DOI)000328720700010 ()2-s2.0-84887089320 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 266271
Available from: 2013-09-18 Created: 2013-09-18 Last updated: 2020-04-01Bibliographically approved
Heralic, A., Christiansson, A.-K. & Lennartson, B. (2012). Height control of laser metal-wire deposition based on iterative learning control and 3D scanning. Optics and lasers in engineering, 50(9), 1230-1241
Open this publication in new window or tab >>Height control of laser metal-wire deposition based on iterative learning control and 3D scanning
2012 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 50, no 9, p. 1230-1241Article in journal (Refereed) Published
Abstract [en]

Laser Metal-wire Deposition is an additive manufacturing technique for solid freeform fabrication of fully dense metal structures. The technique is based on robotized laser welding and wire filler material, and the structures are built up layer by layer. The deposition process is, however, sensitive to disturbances and thus requires continuous monitoring and adjustments. In this work a 3D scanning system is developed and integrated with the robot control system for automatic in-process control of the deposition. The goal is to ensure stable deposition, by means of choosing a correct offset of the robot in the vertical direction, and obtaining a flat surface, for each deposited layer. The deviations in the layer height are compensated by controlling the wire feed rate on next deposition layer, based on the 3D scanned data, by means of iterative learning control. The system is tested through deposition of bosses, which is expected to be a typical application for this technique in the manufacture of jet engine components. The results show that iterative learning control including 3D scanning is a suitable method for automatic deposition of such structures. This paper presents the equipment, the control strategy and demonstrates the proposed approach with practical experiments.

Keywords
Laser metal deposition; Additive layer manufacturing; Metal wire; Iterative learning control; 3D scanning
National Category
Robotics Control Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-4203 (URN)10.1016/j.optlaseng.2012.03.016 (DOI)000305773200008 ()2-s2.0-84861592745 (Scopus ID)
Available from: 2012-03-14 Created: 2012-03-14 Last updated: 2020-04-01Bibliographically approved
Heralic, A. (2012). Monitoring and Control of Robotized Laser Metal-Wire Deposition. (Doctoral dissertation). Göteborg: Chalmers University of Technology
Open this publication in new window or tab >>Monitoring and Control of Robotized Laser Metal-Wire Deposition
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The thesis gives a number of solutions towards full automation of the promising manufacturing technology Robotized Laser Metal-wire Deposition (RLMwD). RLMwD offers great cost and weight saving potentials in the manufacturing industry. By metal deposition is here meant a layered manufacturing technique that builds fully-dense structures by melting metal wire into solidifying beads, which are deposited side by side and layer upon layer. A major challenge for this technique to be industrially implemented is to ensure process stability and repeatability. The deposition process has shown to be extremely sensitive to the wire position and orientation relative to the melt pool and the deposition direction. Careful tuning of the deposition tool and process parameters are therefore important in order to obtain a stable process and defect-free deposits. Due to its recent development, the technique is still manually controlled in industry, and hence the quality of the produced parts relies mainly on the skills of the operator. The scientific challenge is therefore to develop the wire based deposition process to a level where material integrity and good geometrical fit can be guaranteed in an automated and repeatable fashion. This thesis presents the development of a system for on-line monitoring and control of the deposition process. A complete deposition cell consisting of an industrial robot arm, a novel deposition tool, a data acquisition system, and an operator interface has been developed within the scope of this work. A system for visual feedback from the melt pool allows an operator to control the process from outside the welding room. A novel approach for automatic deposition of the process based on Iterative Learning Control is implemented. The controller has been evaluated through deposition experiments, resembling real industrial applications. The results show that the automatic controller increases the stability of the deposition process and also outperforms a manual operator. The results obtained in this work give novel solutions to the important puzzle towards full automation of the RLMwD process, and full exploitation of its potentials.

Place, publisher, year, edition, pages
Göteborg: Chalmers University of Technology, 2012. p. 186
Series
Doktorsavhandlingar vid Chalmers tekniska högskola, ISSN 0346-718X ; 3336
Keywords
Laser Metal Wire Deposition, Additive Layer Manufacturing, Robotic Weld Equipment, Optical Sensors, Process Control, Process Development, Process Stability, Iterative Learning Control
National Category
Robotics Control Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-4206 (URN)978-91-7385-655-3 (ISBN)
Public defence
2012-03-23, F123, Högskolan Väst, Trollhättan, 10:00 (English)
Opponent
Available from: 2012-03-26 Created: 2012-03-14 Last updated: 2020-04-01Bibliographically approved
Heralic, A. & Christiansson, A.-K. (2011). Automatic in-process control of laser metal-wire deposition based on sensor feedback. In: 30th Interantional Congress on Applications of Lasers & Electro-Optics, ICALEO 2011: Orlando October 23-27, 2011. Code 87581|. Paper presented at 30th Interantional Congress on Applications of Lasers & Electro-Optics, ICALEO 2011, Orlando October 23-27, 2011 (pp. 211-220).
Open this publication in new window or tab >>Automatic in-process control of laser metal-wire deposition based on sensor feedback
2011 (English)In: 30th Interantional Congress on Applications of Lasers & Electro-Optics, ICALEO 2011: Orlando October 23-27, 2011. Code 87581|, 2011, p. 211-220Conference paper, Published paper (Refereed)
Abstract [en]

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.

National Category
Robotics Control Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-3714 (URN)
Conference
30th Interantional Congress on Applications of Lasers & Electro-Optics, ICALEO 2011, Orlando October 23-27, 2011
Available from: 2011-09-27 Created: 2011-09-27 Last updated: 2020-04-01Bibliographically approved
Heralic, A., Ottosson, M., Christiansson, A.-K. & Lennartson, B. (2011). Automation of laser metal deposition for the manufacture of fully dense structures. In: Jan-Eric Ståhl (Ed.), 4th International Swedish Production Symposium, SPS11: 3-4 May, Lund, Sverige. Paper presented at SPS11 (pp. 219-227). Swedish Productio Academy
Open this publication in new window or tab >>Automation of laser metal deposition for the manufacture of fully dense structures
2011 (English)In: 4th International Swedish Production Symposium, SPS11: 3-4 May, Lund, Sverige / [ed] Jan-Eric Ståhl, Swedish Productio Academy , 2011, p. 219-227Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Swedish Productio Academy, 2011
Keywords
Laser deposition, metal wire, machine vision, on-line process control
National Category
Control Engineering Robotics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-3712 (URN)
Conference
SPS11
Available from: 2011-09-27 Created: 2011-09-27 Last updated: 2020-04-01Bibliographically approved
Heralic, A., Ottosson, M., Kristiansson, A.-K. & Norlander, T. (2011). Geometry control of laser metal deposition for the manufacture of complex structures in the aero industry. In: 20th International Society for Airbreathing Engines Conference, ISABE 2011: September 12-16, 2011 Gothenburg. Paper presented at XX International Symposium on air breathing engines (pp. 1666-1674).
Open this publication in new window or tab >>Geometry control of laser metal deposition for the manufacture of complex structures in the aero industry
2011 (English)In: 20th International Society for Airbreathing Engines Conference, ISABE 2011: September 12-16, 2011 Gothenburg, 2011, p. 1666-1674Conference paper, Published paper (Refereed)
National Category
Robotics Control Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-3713 (URN)978-1-61839-180-3 (ISBN)
Conference
XX International Symposium on air breathing engines
Available from: 2011-09-27 Created: 2011-09-27 Last updated: 2020-04-02Bibliographically approved
Heralic, A., Christiansson, A.-K., Ottosson, M. & Lennartson, B. (2010). Increased stability in laser metal wire deposition through feedback from optical measurements. Optics and lasers in engineering, 48(4), 478-485
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, p. 478-485Article 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.

Keywords
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: 2020-04-01Bibliographically approved
Heralic, A. (2009). Towards full Automation of Robotized Laser Metal-wire Deposition. (Licentiate dissertation).
Open this publication in new window or tab >>Towards full Automation of Robotized Laser Metal-wire Deposition
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.

Publisher
p. 82
Series
Technical Report, ISSN 1403-266X ; R002/2009
Keywords
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:nbn:se:hv:diva-2148 (URN)
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: 2020-04-01Bibliographically approved
Organisations

Search in DiVA

Show all publications