@inproceedings{MaiwaldTroegerHierl, author = {Maiwald, Frederik and Tr{\"o}ger, Johannes and Hierl, Stefan}, title = {Automated weld seam evaluation and 2D simulation parameter calibration for absorber-free laser transmission welding}, series = {Lasers in Manufacturing Conference (LIM 2023), 26. Juni bis 29. Juni 2023, M{\"u}nchen}, booktitle = {Lasers in Manufacturing Conference (LIM 2023), 26. Juni bis 29. Juni 2023, M{\"u}nchen}, publisher = {Wissenschaftliche Gesellschaft Lasertechnik und Photonik e.V. (WLT)}, pages = {10}, abstract = {Absorber-free laser transmission welding enables clean and precise joining of plastics without additives or adhesives. It is therefore well suited to produce optical and medical devices, which place high demands on cleanliness and accuracy. However, the weld usually has an undesirably large vertical expansion, causing bulges and distortion. To improve this, the intensity distribution of the laser beam as well as the processing strategy must be adapted. Due to the complexity, this is aided by process simulation. However, simulation parameter calibration and verification are usually done considering the seam width and height, which is of limited significance. To overcome this, we propose a new method for image processing of microtome sections, determining the spatially resolved geometry of the weld. Thus, the deviation between experiment and simulation can be calculated pixel by pixel. This spatially resolved value is predestined for the calibration of the simulation parameters: For a parameter field with 18 different settings, the total deviation between experiment and simulation is less than 11 \% after calibration.}, language = {en} } @misc{KaesbauerSchmailzlHierl, author = {K{\"a}sbauer, Johannes and Schmailzl, Anton and Hierl, Stefan}, title = {Simulative investigation on the influence of material- and process parameter on quasi-simultaneous laser transmission welding}, series = {Applied Research Conference - ARC 2017, 7 July 2017 M{\"u}nchen}, journal = {Applied Research Conference - ARC 2017, 7 July 2017 M{\"u}nchen}, editor = {Klippel, Clemens and Mottok, J{\"u}rgen and Reichenberger, Marcus}, publisher = {pro Business GmbH}, address = {Berlin}, language = {en} } @misc{SchmailzlHierl, author = {Schmailzl, Anton and Hierl, Stefan}, title = {FE-Modellbildung der Strahl-Stoff-Wechselwirkung beim Laser-Durchstrahlschweißen in ANSYS 14.0}, series = {ANSYS Conference \& 32th CADFEM Users' Meeting 2014, 04.-06. Juni, N{\"u}rnberg}, journal = {ANSYS Conference \& 32th CADFEM Users' Meeting 2014, 04.-06. Juni, N{\"u}rnberg}, editor = {CADFEM GmbH, and ANSYS Germany GmbH,}, address = {Grafing bei M{\"u}nchen}, pages = {1 -- 15}, language = {de} } @misc{Armbruster, author = {Armbruster, Dominik}, title = {Optimization of a system technology for coaxial online pyrometry in three-dimensional laser transmission welding}, series = {Applied Research Conference 2015 ARC 2015 ; 3rd July 2015 N{\"u}rnberg}, journal = {Applied Research Conference 2015 ARC 2015 ; 3rd July 2015 N{\"u}rnberg}, editor = {Mottok, J{\"u}rgen and Reichenberger, Marcus and Scharfenberg, Georg and Ziemann, Olaf}, publisher = {pro Business GmbH}, address = {Berlin}, pages = {314 -- 317}, language = {en} } @misc{MaiwaldSchmailzlHierl, author = {Maiwald, Frederik and Schmailzl, Anton and Hierl, Stefan}, title = {Thermo-mechanical computation of weld seam geometry in laser transmission welding}, series = {Applied Research Conference - ARC 2017, 7 July 2017, M{\"u}nchen}, journal = {Applied Research Conference - ARC 2017, 7 July 2017, M{\"u}nchen}, editor = {Klippel, Clemens and Mottok, J{\"u}rgen and Reichenberger, Marcus}, publisher = {pro Business GmbH}, address = {Berlin}, language = {en} } @misc{MeisnerKaftiranisMaiwaldetal., author = {Meisner, Dennis and Kaftiranis, Nikitas and Maiwald, Frederik and Rapp, Petra and Hierl, Stefan}, title = {Enhancing Layer Adhesion in Material Extrusion AM with Adaptive Laser Preheating Integrated in Printhead}, series = {LiM Conference 2025, Lasers in Manufacturing, June 23 - 26, 2025, Munich, Germany}, journal = {LiM Conference 2025, Lasers in Manufacturing, June 23 - 26, 2025, Munich, Germany}, publisher = {Wissenschaftliche Gesellschaft Lasertechnik und Photonik e.V.}, abstract = {Material extrusion is a widely used AM process and is gaining more acceptance in industry applications due to its material variety, flexibility, and low cost. However, its usage is limited by a process-related anisotropy caused by insufficient interlayer bonding due to reduced temperature in the process zone. To enhance layer adhesion, an adaptive laser preheating system is integrated in a conventional printhead around the extrusion nozzle. The setup with eight fiber coupled diode laser allows preheating in feed direction and investigation of various intensity profiles. The article describes the experimental setup and significant improvements achieved. Laser preheating with different intensity distributions (spot, sickle or ring shaped) show an incasement of up to 85 \% of the mechanical properties in the build-up direction. However, due to the additional energy input by the laser, controlled cooling of the workpiece becomes a crucial factor and is investigated as well.}, language = {en} } @inproceedings{SchmailzlStegerDostaleketal., author = {Schmailzl, Anton and Steger, Sebastian and Dostalek, Michael and Hierl, Stefan}, title = {Online process monitoring at quasi-simultaneous laser transmission welding using a 3D-scanner with integrated pyrometer}, series = {Proc. SPIE, Laser-based Micro- and Nanoprocessing X, SPIE LASE 2016, San Francisco, California, United States}, booktitle = {Proc. SPIE, Laser-based Micro- and Nanoprocessing X, SPIE LASE 2016, San Francisco, California, United States}, number = {97361J}, editor = {Klotzbach, U. and Washio, K. and Arnold, C. B.}, doi = {10.1117/12.2211705}, pages = {1 -- 7}, abstract = {Quasi-simultaneous laser transmission welding is a well-known joining technique for thermoplastics and mainly used in the automotive as well as in the medical industry. For process control usually the so called set-path monitoring is used, where the weld is specified as "good" if the irradiation time is inside a defined confidence interval. However, the detection of small-sized gaps or thermal damaged zones is not possible with this technique. The analyzation of the weld seam temperature during welding offers the possibility to overcome this problem. In this approach a 3D-scanner is used instead of a scanner with flat-field optic. By using a pyrometer in combination with a 3D-scanner no color-corrected optic is needed in order to provide that laser- and detection-spot are concentric. Experimental studies on polyethylene T-joints have shown that the quality of the signal is adequate, despite the use of an optical setup with a long working distance and a small optical aperture. The effects on temperature are studied for defects like a gap in the joining zone. Therefore a notch was milled into the absorbent polymer. In case of producing housings for electronic parts the effect of an electrical wire between the joining partners is also investigated. Both defects can be identified by a local temperature deviation even at a feed rate of four meters per second. Furthermore a strategy for signal-processing is demonstrated. By this, remaining defects can be identified. Consequently an online detection of local defects is possible, which makes a dynamic process control feasible.}, language = {en} } @inproceedings{SchmailzlHierl, author = {Schmailzl, Anton and Hierl, Stefan}, title = {Rechenzeitoptimierte Temperaturfeldberechnung beim quasisimultanen Laser-Durchstrahlschweißen}, series = {ANSYS Conference \& 33. CADFEM Users' Meeting 2015, 24.-26. Juni 2015, Bremen, Germany}, booktitle = {ANSYS Conference \& 33. CADFEM Users' Meeting 2015, 24.-26. Juni 2015, Bremen, Germany}, editor = {CADFEM GmbH, and ANSYS Germany GmbH,}, address = {Grafing bei M{\"u}nchen}, pages = {1 -- 15}, abstract = {Beim quasisimultanen Laser-Durchstrahlschweißen von Kunststoffen wird bisher die FEM-Simulation wegen der Vielzahl von Uml{\"a}ufen des Laserstrahls und der damit verbundenen hohen Rechenzeit kaum eingesetzt. Um die Temperaturfeldberechnung zur Prozessauslegung und -optimierung praktikabel nutzen zu k{\"o}nnen, ist eine Reduktion der Rechenzeit zwingend erforderlich. Zur Simulation von Schweißvorg{\"a}ngen in ANSYS-CLASSIC werden die thermischen Lasten mithilfe von Ersatzw{\"a}rmequellen auf Basis von APDL-Routinen berechnet. Im Gegensatz dazu wird in dieser Arbeit eine analytische Lastfunktion zur Berechnung der thermischen Last f{\"u}r das quasismultane Laser-Durchstrahlschweißen vorgestellt. Im Vergleich zur Temperaturfeldberechnung mit Ersatzw{\"a}rmequelle kann bei der Berechnung eines dreidimensionalen Modells die Rechenzeit von mehreren Wochen auf wenige Stunden und f{\"u}r ein zweidimensionales auf nur wenige Minuten reduziert werden.}, language = {de} } @techreport{StegerSchmailzlDostaleketal., author = {Steger, Sebastian and Schmailzl, Anton and Dostalek, Michael and Armbruster, Dominik and Hierl, Stefan}, title = {Entwicklung einer Systemtechnik f{\"u}r das quasisimultane Laser-Durchstrahlschweißen von 3D-Kunststoffbauteilen mit Temperaturmessung und Spanndruckregelung}, series = {OTH Forschungsbericht 2016}, journal = {OTH Forschungsbericht 2016}, editor = {Baier, Wolfgang}, publisher = {Inixmedia GmbH}, address = {Kiel}, organization = {Ostbayerische Technische Hochschule Regensburg}, pages = {37 -- 38}, language = {de} } @inproceedings{SchmailzlArmbrusterDostaleketal., author = {Schmailzl, Anton and Armbruster, Dominik and Dostalek, Michael and Steger, Sebastian and Hierl, Stefan}, title = {Strahlf{\"u}hrungs- und -formungskonzept zur koaxialen Temperaturmessung beim scanner-basierten Laser-Durchstrahlschweißen}, series = {2. OTH-Clusterkonferenz, 18. Januar 2017, Techbase, Regensburg, Tagungsband}, booktitle = {2. OTH-Clusterkonferenz, 18. Januar 2017, Techbase, Regensburg, Tagungsband}, editor = {Falter, Thomas}, publisher = {Weber Druck}, address = {Regensburg}, organization = {Ostbayerische Technische Hochschule Regensburg; Ostbayerische Technische Hochschule Amberg-Weiden}, pages = {201 -- 204}, language = {de} } @inproceedings{SchmailzlGeisslerMaiwaldetal., author = {Schmailzl, Anton and Geißler, Bastian and Maiwald, Frederik and Laumer, Tobias and Schmidt, Michael and Hierl, Stefan}, title = {Transformation of Weld Seam Geometry in Laser Transmission Welding by Using an Additional Integrated Thulium Fiber Laser}, series = {Lasers in Manufacturing - LIM 2017, Conference Proceedings}, booktitle = {Lasers in Manufacturing - LIM 2017, Conference Proceedings}, editor = {Esen, Cermal}, address = {M{\"u}nchen}, pages = {1 -- 10}, language = {en} } @inproceedings{ArmbrusterHierl, author = {Armbruster, Dominik and Hierl, Stefan}, title = {Berechnung des Messstrahlengangs f{\"u}r die in einen 3D-Scanner integrierte, pyrometrische Temperaturmessung beim quasisimultanen Laserdurchstrahlschweißen von Kunststoffen}, series = {DVS Congress 2016, Große Schweißtechnische Tagung, DVS Studentenkongress. Vortr{\"a}ge der Veranstaltungen in Leipzig am 19. und 20. September 2016}, booktitle = {DVS Congress 2016, Große Schweißtechnische Tagung, DVS Studentenkongress. Vortr{\"a}ge der Veranstaltungen in Leipzig am 19. und 20. September 2016}, publisher = {DVS Media}, address = {D{\"u}sseldorf}, pages = {165 -- 169}, language = {de} } @inproceedings{ArmbrusterHierl, author = {Armbruster, Dominik and Hierl, Stefan}, title = {Simulation of a pyrometer-based temperature measurement system for quasi-simultaneous laser transmission welding regarding the detectable radiant power}, series = {Applied Research Conference - ARC 2016, 24 June 2016, Hochschule Augsburg, Germany}, booktitle = {Applied Research Conference - ARC 2016, 24 June 2016, Hochschule Augsburg, Germany}, editor = {Mottok, J{\"u}rgen and Reichenberger, Marcus and Stolle, Reinhard}, publisher = {Shaker}, address = {Aachen}, pages = {314 -- 317}, language = {en} } @inproceedings{DostalekHierl, author = {Dostalek, Michael and Hierl, Stefan}, title = {Experimental study to evaluate the influence of clamping pressure variation during laser transmission welding of plastics}, series = {Applied Research Conference 2015 ARC 2015; 3rd July 2015 N{\"u}rnberg}, booktitle = {Applied Research Conference 2015 ARC 2015; 3rd July 2015 N{\"u}rnberg}, editor = {Mottok, J{\"u}rgen and Reichenberger, Marcus and Scharfenberg, Georg and Ziemann, Olaf}, publisher = {pro Business}, address = {Berlin}, pages = {289 -- 294}, language = {en} } @techreport{SchmailzlHierl, author = {Schmailzl, Anton and Hierl, Stefan}, title = {Rechenzeitoptimierte Temperaturfeldberechnung zur virtuellen Prozessauslegung des quasisimultanen Laser-Durchstrahlschweißens}, series = {Forschungsbericht 2014 / Ostbayerische Technische Hochschule Regensburg}, journal = {Forschungsbericht 2014 / Ostbayerische Technische Hochschule Regensburg}, editor = {Baier, Wolfgang}, publisher = {Inixmedia GmbH}, address = {Kiel}, organization = {Ostbayerische Technische Hochschule Regensburg}, pages = {75 -- 77}, language = {de} } @article{QuandtSchaeferHierl, author = {Quandt, Benjamin and Sch{\"a}fer, Felix and Hierl, Stefan}, title = {Heiße Infos aus schwachem Temperatursignal}, series = {Kunststoffe}, journal = {Kunststoffe}, number = {12}, publisher = {Hanser}, address = {M{\"u}nchen}, issn = {0945-0084}, pages = {65 -- 68}, language = {de} } @article{SchmailzlStegerHierl, author = {Schmailzl, Anton and Steger, Sebastian and Hierl, Stefan}, title = {Process monitoring at laser welding of Thermoplastics}, series = {Laser Technik Journal}, volume = {12}, journal = {Laser Technik Journal}, number = {4}, doi = {10.1002/latj.201500029}, pages = {34 -- 37}, abstract = {A pyrometer, integrated into a 3D-scanner, offers the possibility to measure the weld seam temperature at quasi-simultaneous laser transmission welding. Experimental studies have shown that gaps located in the joining zone can be identified by a temperature rise even at a high scanning velocity. This enables the implementation of algorithms for observation and control strategies.}, language = {en} } @article{DostalekStegerSchmailzletal., author = {Dostalek, Michael and Steger, Sebastian and Schmailzl, Anton and Hierl, Stefan}, title = {Detecting Defects Reliably}, series = {Kunststoffe International}, volume = {105}, journal = {Kunststoffe International}, number = {12}, pages = {37 -- 40}, abstract = {The integration of a broadband pyrometer in a 3-D scanner enables a continuous and local temperature measurement during the quasi-simultaneous laser transmission welding process. Welding tests on polyethylene samples show that defects can be clearly identified based on the temperature signal, despite a high scanning velocity.}, language = {en} } @inproceedings{SchmailzlHierl, author = {Schmailzl, Anton and Hierl, Stefan}, title = {Thermo-mechanische Struktursimulation mit ANSYS Workbench 14.0 am Beispiel des Laser-Durchstrahlschweißens}, series = {ANSYS Conference \& 31st CADFEM Users' Meeting - ACUM, June 19-21, Mannheim}, booktitle = {ANSYS Conference \& 31st CADFEM Users' Meeting - ACUM, June 19-21, Mannheim}, editor = {CADFEM GmbH, and ANSYS Germany GmbH,}, address = {Grafing bei M{\"u}nchen, Darmstadt}, pages = {1 -- 16}, language = {de} } @techreport{TalbotHierlSchmailzl, author = {Talbot, Sebastian and Hierl, Stefan and Schmailzl, Anton}, title = {Thermische FEM-Simulation des Laser-Durchstrahlschweißens}, series = {Forschungsbericht 2013}, journal = {Forschungsbericht 2013}, editor = {Baier, Wolfgang}, address = {Kiel}, organization = {Ostbayerische Technische Hochschule Regensburg}, pages = {45 -- 46}, language = {de} }