ROBOT-ASSISTED PROCESSING


segments, which are cut in such a way that when their faces meet, they form a prescribed shape that allows us to go from our entry point to our target without touching any of the surrounding blades or components. Te optical system is then fixed in place and can’t move.’ Before a repair can be carried out, the size and


depth of the damage is first determined using a scope equipped with either stereovision or point cloud technology. Tis information is then entered into a computer program, which drives the mirror through the tool path to conduct the repair. Te process is monitored using third-party imaging equipment inserted through the next closest access port, similar to keyhole surgery. Te material and laser interaction


Fibre-delivered vehicles Te combination of fibre laser and robot is already well established in automobile production, but according to Michael Kuhn, European manager of laser technical sales support at Fanuc, the full potential of the technology is yet to be reached. ‘Te capabilities of a laser process are limited by


science for the new method was developed in collaboration with the University of Nottingham, which Rolls-Royce is continuing to work with to develop other snake-like robots, according to Kell. ‘Te intention is that these miniature laser heads – or other end effectors that we are yet to develop or are in the process of developing, such as tools that apply coatings – will sit on the end of these robotic deployment devices and effectively allow us to have a miniaturised toolkit on the end of a steerable robotic probe.’ Rolls-Royce is also investigating putting additive


manufacturing capabilities on its snake-like robot, as there is a limit to how much material can be removed in a blending repair before the structural integrity of a compressor blade is compromised. ‘We [Rolls-Royce] are working on ways of


depositing material back onto a [compressor] blade edge, such that we can repair larger bits of damage,’ Kell said, explaining that currently damage of up to 1mm3 in volume can be repaired using the flexible laser probe. ‘We would grind bits away and then build them back up, rather than leaving a scallop as we do now,’ he continued. ‘Tis will be incredibly challenging to do at component level in situ, and we are currently in the process of validating if this will be possible using our new snake-like equipment.’ In theory, according to Kell, repairs made with


the flexible laser probe could one day take place remotely from Rolls-Royce’s availability centre in a completely different part of the world to the engine. ‘We’re moving more towards this remote maintenance and being able to make repair decisions more quickly,’ he said. Te company is still in the process of internally


validating the new method, and is very close to including it in the suite of repair solutions it offers. ‘Tis is the year where we will begin using the laser boreblend scope over traditional blending methods,’ Kell confirmed.


www.lasersystemseurope.com | @lasersystemsmag


are working on ways of depositing material back onto a [compressor] blade edge


We [Rolls-Royce]


the robot itself. As it stands, there are some limitations in terms of dynamic path accuracy and repeatability with robots, as their kinematics are designed mainly for handling purposes, where micron-scale accuracies are not that important,’ Kuhn said. ‘For cutting applications, however, accuracies of 50µm or less become important, but this cannot currently be achieved with available robot systems. ‘Tere is therefore a huge need


for more precise robots for laser applications. If we are able to improve the dynamic path accuracy of our robots we would certainly create a revolution in


the market, as robot systems could then be used to compete with the 3D machine tool market for 3D laser cutting and 3D welding machines.’ Improving the accuracy of robots is therefore


key. Kuhn observed that robots probably won’t be able to match the dynamic path accuracy of Cartesian machine tools, but that engineers at Fanuc are ‘on the way to coming close to this’. ‘As Fanuc produces both fibre lasers and robots,


we know the exact requirements for combining the two technologies,’ Kuhn said. ‘I believe we will achieve very good results in the future that will


make the robot-fibre laser combination very competitive against fibre machine tools.’ In cooperation with its parent company


Furukawa Electric, Fanuc launched its own fibre laser technology in 2015, the power of which ranges between 500W and 6kW, with the firm planning to go beyond 6kW in the future. As the company also develops CNC controls and


drive technology, Fanuc is in the rare position of being able to produce dedicated functions and interfaces for laser cutting and welding, which together increase the efficiency of such robot- assisted processes – the high control speed gave short latency times between the power command and execution of its lasers. In the future the firm also plans to integrate a


scanning unit into its systems to help bring their accuracy closer to that of Cartesian machine tools. ‘We are going to implement the robot, laser and scanner control in one device, and this gives a lot of advantages on the market,’ said Kuhn.


Dynamic diodes Direct diode lasers are also gaining interest in industry, but they are yet to match the beam quality of fibre or CO2 lasers. Of particular interest to machine integrators, however, is the opportunity presented when direct diode lasers are combined with robotics. ‘Direct diodes are very compact, as their housing


is quite small, which means they can be easily connected to, or carried by, a robotic arm,’ explained Kuhn. While a fibre laser is normally separate from a robot arm, with its light guided through a flexible


Fraunhofer ILT’s LaserTAB solution, shown at Productronica, consists of a weld monitoring system on a Kuka robot ISSUE 38 • SPRING 2018 LASER SYSTEMS EUROPE 15


Fraunhofer ILT


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