ROBOT-ASSISTED PROCESSING


fibre to the processing head, a diode laser can be integrated directly onto the arm. Tis could bring benefits such as a smaller physical footprint, higher flexibility and higher reliability, according to Kuhn. ‘It’s not that easy to turn a processing head 360


degrees when a fibre is attached, whereas with a direct diode laser this wouldn’t be a problem,’ he said, explaining that a fibre can be damaged when bent frequently by the robot arm. ‘Te fibre laser is also very sensitive to vibrations, whereas direct diodes are less sensitive to this.’


Robotic sight Robot-assisted welding is in high demand by the automotive industry, with technology firms such as Blackbird Robotersysteme experiencing particular interest in its systems for manufacturing hang-on- parts, seat parts and heat exchangers. To ensure manufacturers are achieving


high-quality, high-precision weld seams, Blackbird’s partner Scanlab has developed a real-time monitoring solution that, together with Blackbird’s own Scan Control Unit, enables full, on-the-fly seam monitoring and laser spot adjustment. Designed for mounting on robots such as those


from Fanuc and Kuka, Scanlab’s IntelliWeld 3D scan system is capable of positioning a laser beam along the 3D contours of automotive parts. Manipulating the beam keeps any robot movement to a minimum, which is ultimately a faster process as weld-to-weld positioning times can be reduced to a few milliseconds. ‘It allows the customer to reach optimised cycle


times in production,’ commented Florian Kiesch, product manager at Blackbird Robotersysteme. ‘Te first step is to record the robot path and to calculate the welding seams and the timing. In the next step the customer can optimise their robot path for a reduced cycle time.’ Te IntelliWeld features prefocus


Scanlab’s IntelliWeld system gives on-the-fly weld seam monitoring and laser spot adjustment along the contours of automotive parts


process chain flexibility in body construction’. Together with TUM’s Institute for Machine Tools and Industrial Management, BMW, Emil Bucher, Application Technology and Precitec, Blackbird Robotersysteme and Scanlab are investigating how OCT technology could provide more flexibility in automotive body construction, particularly in electromobility. Te project will combine an OCT scanner –


optics that are optimised for fibre-coupled disk lasers, or fibre lasers with powers up to 8kW, and enable precise contour tracking for fillet welds. Scanlab’s newest addition to the IntelliWeld family, the IntelliWeld II, also offers an integrated zoom axis, which makes it particularly well suited for overlap welding, as its variable spot size can weld flexible seam widths. Both the IntelliWeld and Scan Control Unit are


currently being combined with optical coherence tomography (OCT) to enhance automotive welding applications as part of the RoKtoLas project – ‘Robot-supported, scanner-based optical coherence tomography in remote laser welding for


16 LASER SYSTEMS EUROPE ISSUE 38 • SPRING 2018


will achieve very good results in the future that will make the robot- fibre laser combination very competitive


I believe we


employing single-point high-speed distance measurement based on interferometry – with additional photonic sensors to inspect weld seams using integrated edge tracking and seam topology measurement. Te solution, known as xHawk, will give measurements ahead of, within, and past the laser process zone, identifying potential weld defects such as inadequate width, penetration, open pores and faulty positioning. Fraunhofer ILT has also developed


its own robot-assisted weld monitoring solution for welding prismatic, round and pouch battery cells. Known as LaserTAB – laser- based tape-automated bonding – the


monitoring solution features a pyrometer, a co-axial camera, a relay-optic and a mounted spacer, all fixed to Kuka’s intelligent industrial work assistant robot. Similar to Fanuc’s technology, an external single-mode fibre laser delivers light through a flexible fibre to the optical head mounted on the robot. ‘Te LaserTAB process offers the possibility to


compensate tolerances of the batteries or other electric components,’ said Johanna Helm, of Fraunhofer ILT’s micro joining division. ‘Battery


cells have a wide tolerance range. When they are assembled in a module the tolerances may even increase, which makes it very difficult to weld automatically with a laser. With the integrated spacer, tolerances can be compensated for and larger differences in height between the different components can be bridged.’ Te integrated spacer is a tool that maintains a


fixed distance between the optics and the point of welding, ensuring that the focal length required for the process is met. Te robot is then able to ‘feel’ the moment the spacer touches the workpiece and start welding. A 1kW 1,070nm fibre laser is used in this instance. Te system’s relay optic is designed to extend the optical system and enable a deeper immersion depth for welding battery pack parts that are difficult to access. At the moment LaserTAB is guided to the


welding point by hand, but Helm explained that it could one day be taught various welding positions, meaning a human would then need to simply supervise the automated production and only correct the position when necessary. ‘In the future this tool should serve as a process


control mechanism, to adjust the process during welding and to identify bad parts in line,’ Helm commented. ‘At the moment we are looking for an industrial partner who is interested in this technology and is willing to implement or establish this type of welding into their production process.’ Fraunhofer ILT will be demonstrating


LaserTAB on 3 May as part of the international laser congress AKL in Aachen, Germany. Te technology was also demonstrated last year at the Productronica trade fair in Munich, Germany, where it was used to connect a copper contact element to a round cell.


@lasersystemsmag | www.lasersystemseurope.com


Scanlab


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