Welding robots: Lightweight and fail-safe

• What was needed: triflex® R multi-axis energy chain made of the refractory material igumid ® NB, drylin® SLW linear modules, PRT-04 rotary table bearings
• Requirements: With rotations of at least 360 degrees, all cables must be guided safely. Even high temperatures during welding and contact with hot sparks must not cause any problems for the cable routing. The suspension and guidance of the welding head should enable millimetre-precise adjustment.
• Industry: Robots
• Success for the customer: 360 degree rotations are now possible without wear on the cable. As the e-chain® is made of igumid® NB, flying sparks cannot harm it. Completely lubrication- and maintenance-free bearings were found for the suspension of the welding head, which are fail-safe and lightweight.

DIN Tools is a company based in Heist-op-den-Berg near Antwerp, Belgium, specialising in the development of welding automation and robots. A welding robot commissioned from DIN Tools by Smulders - a French construction company - is designed to produce circular and uninterrupted weld seams. The prototype will later be able to weld 2,400 nozzles per day and thus, for example, produce transitions between foundations and wind turbine towers in offshore wind turbines safely and better than any human.
Visually, the welding robot resembles a pneumatic hammer. An employee positions the robot and starts the welding process. The robot now makes a 360-degree turn with an additional 6-degree overlap and welds the nozzle to the foundation. Even if the welding process is carried out hundreds of times a day, it outperforms even experienced employees in terms of quality and continuity and is therefore more important than ever, especially in times of a shortage of skilled labour.
When building the welding robot, Bart Lourdaux, the Inhaver at DIN Tools, and his colleague, Project Manager Kevin Wijns, were particularly confronted with the problem of cable routing. The team had to find a way to safely route the cables and hoses for power and welding wire. And in such a way that they can withstand rotations of at least 360 degrees without rubbing against each other and wearing out or catching on each other and thus impairing the welding quality. High temperatures during welding and contact with hot sparks must not cause any problems either.
In addition to the cable routing, a second challenge was the suspension and guidance of the welding head. The customer's requirement was to be able to adjust the head with millimetre precision using two axes.

As the CEO of DIN Tools has been working with us since 2004, the solution to the cable problem was already within reach. Today, a triflex® R is used, a three-dimensional e-chain® made of high-performance plastic. The power cable and the hose for feeding the welding wire can be easily fixed inside the e-chain®. Each chain link allows a torsion of 10 degrees. The e-chain® can be reinforced with a fibre-rod to prevent the formation of loops. 360 degree rotations are possible without wearing the cable. At the same time, the cables do not hinder the robot in its work. As the e-chain® is made of igumid® NB, flying sparks cannot harm it. The high-performance plastic can withstand temperatures from -40 °C to +80 °C trade show, has high abrasion resistance and is robust.
Compact SLW linear modules with torsion-resistant aluminium double-shaft profiles from the drylin® series and the flat PRT-04 rotary table bearing are used to suspend the welding head. The welding head is positioned using a trapezoidal threaded spindle with manual drive. The bearings are made of high-performance plastics and, unlike metal bearings, enable low-maintenance dry operation. A solid lubricant integrated in the plastic is released by micro-abrasion and creates a self-lubricating effect on the shaft surface. Nobody has to relubricate, no lubricant has to be provided and no instructions are required. As dust and dirt particles quickly combine with lubricants and lead to the failure of conventional bearings, dry operation also means reliability. Finally, the linear modules and rotary table bearings made of aluminium score points with their low weight. The welding robot weighs around 18 kg and is light enough for an employee to lift it with their hands.