Long, difficult and dirty: A linear guide system for a complex setup
02 November 2020
Spie GmbH is responsible for the repair, maintenance and refurbishment of machinery for a leading train manufacturer in Germany. It was faced with a difficult problem: an old DUO welding system was breaking down more than it was in operation – and it was giving the company a constant headache.
"We had to visit the customer almost every week, with two men working two or three shifts to maintain the welding machine. This was not economically viable for us and it was a huge problem for our customer as these failures meant the machine was often at a standstill, with a knock-on impact on other plant processes," explains Günter Becker, Deputy Branch Manager of Spie GmbH.
The welding system is enormous – 30 metres long and 10 metres wide. On each of the two welding machines, four robots are mounted, two on the lower and two on the upper level. In a slow but constant movement, the robots weld aluminium assemblies of up to 28 metres long to a wagon shell. The robots are mounted to individual rack-driven carriages, each driven by a motor, which run on two guide rails.
Repair – yes, standstill – no
“We were looking for a linear guidance system that could operate in a very dirty environment, under constant load and with an unusually long track length. We needed a long-term solution that could be installed on the existing machine,” says Becker.
"The problems we faced with the machine were multi-faceted. From a construction point of view, the key difficulty was that the existing welding system from the 1990s had been built with an inadequate drive and guidance system. [This was] not suitable for heavy loads or such a dirty working environment.
"The existing rail systems had also been mounted on milled surfaces that were not perfectly flat. In addition, the guide rails were heavily worn due to the loads they had seen," explains Becker. This not only caused the drive motors to fail regularly but also meant that the seams were not neat. Furthermore, dirt particles made their way into the recirculating ball bearings in the guide blocks for each welding robot – a common issue in this type of environment. This accelerated wear and contributed to the frequent blocking of the motors.
Read the full article in the November issue of DPA
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