Whereas until recently the frames of safety cabins were tacked and welded manually and welding robots were only used to weld subassemblies, whole safety cabins are now completely welded by robots at Sekura.
For this purpose, Sekura Cabins A/S in Randers, Denmark started using a new welding robot installation from Valk Welding. The logistics of exchanging the cabins in the different working stations is also automated. For that, a transport system with a pallet changer is installed. With this, Sekura Cabins makes big steps both with process and quality improvement of their products.
Sekura Cabins is specialized in the design, development, and complete production of high-quality cabins for industrial and off-highway vehicles, commissioned by large OEMs. A total of 15 different cabins with a variety of series size are delivered within 14 days after order intake. The welding of the frames according to ISO 3834 is a quality determining part of the production.
Welding robots on H-frame
On the three existing welding robot installations, Panasonic TA-1900 welding robots weld on an H-frame, 2D parts of the frames and subassemblies. Those are delivered to the department where the frames are composed in adhesive molds and completely welded manually, together with the other metals. After powder coating, the frames are finished at the assembly.
Prevent size deviations
Adviser Michiel Som on behalf of Standard Investment: “After taking over Sekura’s activities of the Bosal group at the beginning of 2017, we first took a closer look at the production process. It turned out, the welding was an especially sensitive process because the quality completely depended on the manual welders. This causes risks of deviations with the dimensions. By welding the cabins completely with a welding robot, we want to exclude those risks. Especially the Touch Sensing function (wire searching) has played a significant role here.”
A second important reason to weld the cabins completely with the robot is to get a prettier, and smoother welding seam on the outside. “Because you won’t need to finish the seam anymore, the post-process of grinding and sanding is not needed anymore,” Michiel Som explains.
Welding robot on XYZ system
To be able to reach every position of the cabins optimally, Valk Welding chose a concept where the welding robot hangs on an XYZ system and the cabins are rotated by a 3-ton manipulator. Valk Welding has previously delivered such a system to the Danish manufacturer Sjörring. Although, that was a 10-ton manipulator.
Shorten process time
The cabins are tacked in a separate department, and thereafter, put on a pallet system in a transport system, and, with the help of an automated exchange table, put on the manipulator. The idea behind this construction of a transport system with two rows and an automatic pallet exchanger is being able to expand the system with two identical welding robot installations on the other side in the future. Managing Director Carsten Tonnes: “Every cabin is custom built, the series size may not affect the process time. To shorten process times of the welding process, even more, we started programming offline with DTPS. The XYZ system is too complex to programm online anyway. To learn to work with both the robot and the DTPS software quicker, we make programms for the welding robot together with the specialists of Valk Welding DK.’’
“Because cabins consist of pipe and tube profiles of various sizes and thicknesses, we have to deal with large welding openings. To solve that, we now work on the improvement of the set-up. A next step is to cut the profile parts with a tube laser, so you can ‘click’ the parts into each other, instead of having to attach them. Furthermore, we want to use DTPS in the set-up to be able to check the accessibility in an early stage. The use of Virtual Reality could be a great help,” Michiel Som concludes.
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