Now showing 1 - 7 of 7
  • Publication
    Design of freeform optic module creating a ring-shaped laser beam profile for localized heating of sheet metals
    Laser-based preheating is an energy-efficient method to locally enhance the formability of a metal sheet. A ring-shaped beam can be used for preheating in the flange forming process. According to the tailored heat principle, only the area to be formed is heated. In this paper, a method is presented to design modules with reflective freeform optics (FFO) that converts a collimated Super-Gaussian beam into a ring-shaped beam at a working distance of e.g. 170 mm and deflects the laser beam by 90° simultaneously. The FFO design is based on a 2D geometric model of the optical system and is iteratively optimized according to the process requirements. The FFO was manufactured by fast tool diamond turning and placed into an integration model within a progressive die tool. The design was verified by beam profile measurement as well as by analyzing the formed part quality.
  • Publication
    System development for active deviation compensation in laser-based wire micro deposition using image recognition
    Gold plating is used to protect electrical components from corrosion and enhance functionality. A sustainable alternative is localized laser-based wire deposition: Using a laser scanning system, micro gold wires are welded into gold spots locally on the component surface. However, process and system tolerances lead to deviations between the target and actual weld positions. This paper presents a system for active deviation compensation using an on-axis camera and image recognition algorithms. Different adaptive thresholding methods and image processing algorithms are used to determine the welding target position on the part. The actual welding point of the wire on the component is calculated and transferred to the scanner as the new welding position. An approach for designing such a system for active deviation compensation and the possibility of higher-level communication with industrial controls is presented.
  • Publication
    Optimierte Prozesse mithilfe lokaler Erwärmung und KI
    Konventionelle Verfahren zur Blechbearbeitung wie das Scherschneiden oder Umformen stoßen bei Hochleistungswerkstoffen häufig an ihre Grenzen. So sind einwandfreie Schneid- und Umformergebnisse bei hochfesten Blechen aus Stahl, Aluminium oder Titan in Transfer- und Folgeverbundwerkzeugen nur schwer zu erreichen. Optimierte Blechbearbeitungsprozesse mit thermischer Unterstützung sowie (Mensch-zentrierten) KI-Applikationen sind eine Möglichkeit, um den steigenden Qualitätsanforderungen gerecht zu werden.
  • Publication
    CaliBend: A flexible, cost-effective laser module for thermal-assisted bending of high-strength steels
    ( 2020)
    Carbonell-Sanromà, Eduard
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    Panick, Daniel
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    Montiel i Ponsoda, Joan J.
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    Melchers, Christian
    "CaliBend" proposes a direct diode laser approach for thermal assisted processing of steel sheets. Our module aims at enabling bending processes of high-strength steels (HSS) and with minimal bending radii without inducing damage to the metal part. In this work we present a laser source integrated on an industrial servo press for continuous die processing. The metal sheet is heated up locally by laser radiation before the bending stroke. By reaching power densities close to 40 W/mm2, the bending line of the metal sheet reaches the hot forming temperature regime in under two seconds allowing a faultless while increasing the typically low forming limits of HSS.
  • Publication
    Entwicklung und Herstellung eines High-Power Linsenprismas
    ( 2017-06) ; ; ;
    Zenz, Manuel
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    Pemsel, Alexandra
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    Grafov, Artur
    Ein wassergeführter Hochleistungslaserstrahl war der Ausgangspunkt für die gemeinsame Entwicklung einer kompakten Spezialoptik.
  • Publication
    Realization and first time operation of a high-power laser-water-jet system
    Micromachining industry successfully uses the advantageous properties of laser-water-jets (LWJ), e.g. high depth of field, cooling and cleaning effect of water as well as high kerf parallelism. Until now short-pulsed laser sources with average powers of few 100 W are the main beam sources used in laser-water-jets applications. In machining, the comparably low average powers limit processing speeds, especially when high material thicknesses are present. The objective of ongoing research at Fraunhofer IPT is to expand the range of possible applications for laser-water-jets to macro laser processing by using a continuous-wave fiber laser source with a maximum average power of 30 kW. Using high laser power within a macro-water-jet enables a significant increase in processing speeds while maintaining the above-mentioned beneficial properties of laser-water-jets. In a previous publication, using up to 2 kW laser power of an infrared fiber laser coupled in a laser-water-jet generated by an industrial micro machining system, the need for a dedicated high-power laser system, capable of dealing with thermo-optical and thermo-mechanical issues, was identified. For the first time a laser head for the generation a laser-water-jet for macro machining has been designed, built and tested in a new high-power laser test rig with active laser safety at Fraunhofer IPT. In order to increase the transmittable laser power the internal water supply was up-scaled to high flow rates and specialized high power optics as well as suitable cooling strategies were developed to ensure increased thermal stability. Using a 30 kW fiber laser the new machining head is tested and its thermal stability is investigated. The effects of system stability on the water-jet properties are studied in order to identify further system improvement. Finally, possible applications for using the new technology are outlined and first processing trials are performed.
  • Publication
    Thermal investigation of interaction between high-power CW-laser radiation and a water-jet
    The technology of a water guided laser beam has been industrially established for micro machining. Pulsed laser radiation is guided via a water jet (diameter: 25-250 mm) using total internal reflection. Due to the cylindrical jet shape the depth of field increases to above 50 mm, enabling parallel kerfs compared to conventional laser systems. However higher material thicknesses and macro geometries cannot be machined economically viable due to low average laser powers. Fraunhofer IPT has successfully combined a high-power continuous-wave (CW) fiber laser (6 kW) and water jet technology. The main challenge of guiding high-power laser radiation in water is the energy transferred to the jet by absorption, decreasing its stability. A model of laser water interaction in the water jet has been developed and validated experimentally. Based on the results an upscaling of system technology to 30 kW is discussed, enabling a high potential in cutting challenging materials at high qualities and high speeds.