1.
Ancona, Antonio, 1974-, et al.
(author)
Monitoring and control of directed energy deposition using a laser beam
2023. - 1.
In: Additive Manufacturing of High-Performance metallic Materials. - : Elsevier. - 9780323918855 - 9780323913829 ; , s. 612-638
Book chapter (peer-reviewed) abstract
To be a successful competitor among other technologies, metallic laser-directed energy depositionusing a laser beam would benefit from the support of intelligent automation making the processrobust, repeatable, and cost-efficient. This calls for technology leaps towards robust and accuratedetection and estimation of the conditions during processing and control schemes for robustperformance. This chapter discusses how developments in sensor technology and model-basedsignal processing can contribute to advancements in in-process monitoring of directed energydeposition using a laser beam and how developments in model-based feedforward- and feedbackcontrol can support automation. The focus is on how machine vision, optical emission spectroscopy,thermal sensing, and electrical process signals can support monitoring, control and better processunderstanding. These approaches are industrially relevant and have a high potential to support amore sustainable manufacturing.
2.
Christiansson, Anna-Karin, 1947-, et al.
(author)
Automation of a robotised metal deposition system using laser melting of wire
2008
In: 18th International Conference on<em> </em>Flexible Automation and Intelligent Manufacturing (FAIM 2008). - 9789163327575 ; , s. 122-129
Conference paper (other academic/artistic) 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.
3.
4.
De Backer, Jeroen, 1987-, et al.
(author)
Temperature control of robotic friction stir welding using the thermoelectric effect
2014
In: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 70:1-4, s. 375-383
Journal article (peer-reviewed) abstract
Friction stir welding (FSW) of non-linear joints receives an increasing interest from several industrial sectors like automotive, urban transport and aerospace. A force-controlled robot is particularly suitable for welding complex geometries in lightweight alloys. However, complex geometries including three-dimensional joints, non-constant thicknesses and heat sinks such as clamps cause varying heat dissipation in the welded product. This will lead to changes in the process temperature and hence an unstable FSW process with varying mechanical properties. Furthermore, overheating can lead to a meltdown, causing the tool to sink down into the workpiece. This paper describes a temperature controller that modifies the spindle speed to maintain a constant welding temperature. A newly developed temperature measurement method is used which is able to measure the average tool temperature without the need for thermocouples inside the tool. The method is used to control both the plunging and welding operation. The developments presented here are applied to a robotic FSW system and can be directly implemented in a production setting.
5.
Elefante, Arianna, et al.
(author)
Detecting beam offsets in laser welding of closed-square-butt joints by wavelet analysis of an optical process signal
2019
In: Optics and Laser Technology. - : Elsevier BV. - 0030-3992 .- 1879-2545. ; 109, s. 178-185
Journal article (peer-reviewed) abstract
Robotized laser beam welding of closed-square-butt joints is sensitive to the positioning of the laser beam with respect to the joint since even a small offset may result in a detrimental lack of sidewall fusion. An evaluation of a system using a photodiode aligned coaxial to the processing laser beam confirms the ability to detect variations of the process conditions, such as when there is an evolution of an offset between the laser beam and the joint. Welding with different robot trajectories and with the processing laser operating in both continuous and pulsed mode provided data for this evaluation. The detection method uses wavelet analysis of the photodetector signal that carries information of the process condition revealed by the plasma plume optical emissions during welding. This experimental data have been evaluated offline. The results show the potential of this detection method that is clearly beneficial for the development of a system for welding joint tracking.
6.
Ericsson, Mikael, 1975-, et al.
(author)
Virtual Commissioning of Machine Vision Applications in Aero Engine Manufacturing
2018
In: Proceedings of The 15th International Conference on Control,Automation, Robotics and Vision, November 18-21, 2018. - 9781538695814 ; , s. 1947-1952
Conference paper (peer-reviewed) abstract
New aero engine design puts new demands on the manufacturing methods with increased automation level. Therefore, the use of vision sensors for control and guiding of industrial robots is being increasingly used. In such system, it is need to customise the machine vision system with real components in the real environment which is normally done close to the start-up of the production. This paper addresses a new concept for designing, programming, analysing, testing and verifying a machine vision application early in the design phase, called Virtual Machine Vision. It is based on a robot simulation software where the real machine vision application is simulated before the implementation in the production line. To verify the Virtual Machine Vision concept an advanced stereo vision application was used. Using two captured images from the robot simulated environment, camera calibration, image analysis and stereo vision algorithms are applied to determine a desired welding joint. The information of the weld joint, i.e. robot position and orientation for the weld path, are sent from the machine vision system to the robot control system in the simulation environment and the weld path is updated. The validation of the Virtual Machine Vision concept using the stereo vision application is promising for industrial use, and it is emphasised that the same programs are used in the virtual and real word.
7.
Hagqvist, Petter, et al.
(author)
Automation of a laser welding system for additive manufacturing
2015
In: Proceedings of the 2015 IEEE International Conference on Automation Science and Engineering. - : IEEE. - 9781467381826 ; , s. 900-905
Conference paper (peer-reviewed) 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.
8.
Hagqvist, Petter, et al.
(author)
Resistance based iterative learning control of additive manufacturing with wire
2015
In: Mechatronics (Oxford). - : Elsevier BV. - 0957-4158 .- 1873-4006. ; 31, s. 116-123
Journal article (peer-reviewed) 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.
9.
Heralic, Almir, 1981-, et al.
(author)
Automation of Robotized Laser Metal-Wire Deposition
2007
In: Proceedings of the ninth IASTED International Conference on Control and Applications. - : ACTA Press. - 9780889866652 ; , s. ID 658-075-
Conference paper (peer-reviewed)
10.
