SHOW REPORT: ILAS 2019
welded successfully. The power required to perform welding at 5mm thicknesses could not be sent through the head, Kirk commented. The power that could be
UKAEA has developed two processing heads that can fit down the inside of a 90mm-wide reactor cooling pipe, to perform cutting and welding applications
gEnergy Authority (UKAEA), described to attendees how it – in collaboration with TWI and Cranfield University – has been developing compact laser cutting and welding heads for decommissioning components in its fusion reactors. Whenever a component in a fusion reactor needs to be removed and replaced, the many cooling pipes surrounding it have to be cut and re-welded. These pipes have an inside diameter of 90mm – no larger than a pint glass, Kirk said – and walls that are 5mm thick. To this end, the UKAEA has been developing prototype in-bore robotic tools that can perform laser cutting and welding processes in these pipes. The prototype laser tools include a novel miniaturised laser head design to fit in the pipe and apply the laser processes at a short standoff distance of around 25mm. The heads include a clamping function that stabilises and aligns them in the pipe, and a rotary function that enables the laser to be used to either cut or weld around the entire inside of the pipe. The clamping function of the welding tool also includes a large pneumatic actuator that clamps onto either side of the gap and pulls together so the weld can be performed. While the cutting tool was trialled with a similar feature, which would work the other way and pull the sides of the cut apart, Kirk noted trials revealed this function wasn’t particularly needed.
The trials demonstrated that the cutting head could
10 LASER SYSTEMS EUROPE SUMMER 2019
achieve full penetration cuts on 5mm-thick pipes made of two types of steel (P91 and 316L) in approximately 34 seconds. The laser binds the kerf material to the exit side of the cut, which significantly reduces the amount of secondary waste that later needs to be dealt with. For the initial demonstrator trials the quality of the cuts was not a primary concern, Kirk said, but explained later that further development of the cutting head and processing parameters could, in the future, make it possible to produce cuts that are re-weldable. Trials of the welding head, on the other hand, demonstrated that, while full penetration welds could not be achieved on steel pipes of the required 5mm thickness, pipes that were 3mm thick could in fact be
sent through the welding (and cutting) head successfully was up to 2.3kW. Kirk added that while a lot of individual components were rated to about 5kW, the cooling systems of the heads – argon gas flowed through the central optical cavities – can only hold on for so long at this power. An additional issue, Kirk said, was the laser spot size used for welding and cutting was limited to around 0.8mm. This was due to the short standoff distance of around 25mm between the head and the pipe, which means only very short focal length optics can be used.
One tool, three applications On day two of the symposium, an upcoming technology that caught my attention was the multifunctional processing head under development in the European Horizon 2020 project ModuLase, coordinated by TWI, which began in late 2016 and is due to continue for another nine months. The new processing head,
according to Dr Jon Blackburn, manager of TWI’s laser and sheet processes group and
vice president of AILU, will be capable of performing three processes: welding, cutting and cladding. This will be achieved through three interchangeable end effectors – one for each process. Currently these end effectors have to be changed manually. However, Blackburn assured that this will eventually be done via an automated robotic tool changer. What drew my attention to this multi-functional system was the interest it has sparked among manufacturers. The technology was originally intended for job shops and tier-2/3 manufacturers, that not only undertake a lot of high- variety projects at relatively low volume, but who also might not have the budget to procure a range of different processing heads, or the expertise required to support a wide variety of
“The technology was originally intended for job shops and tier-2/3 manufacturers… the project has since attracted a lot of attention from larger, tier-1 manufacturers”
The ModuLase project has developed a processing head that can perform cutting, welding and cladding through three interchangeable end effectors
@lasersystemsmag |
www.lasersystemseurope.com
UKAEA
ModuLase project
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