Tough operating conditions, limited space - and all this at high acceleration forces and cycle rates that impact the energy supply system. In the past, this led to costly downtime of the handling robots, which amounted to a six-figure sum each year. It is not surprising, therefore, that MA Automotive Deutschland GmbH converted to low-profile triflex energy chain systems that can be moved in three dimensions. Since then, plant availability has significantly increased.
"Three compaction units and eight assembly lines as well as about 100 robots are in use", says Steffen Modes, Manager Maintenance Shell of MA Automotive Deutschland in Treuen, Saxony, about the highly complex machine park. The company is part of the CLN Holding (MA Automotive, among others), Italy's largest steel service centre based in Turin. The group has 34 locations in Europe and two oversea production sites.
In the Vogtland location, about 185 employees have been focussing on producing individual, structural and body components made of steel and aluminium since the plant opened in 2004. "We consider ourselves to be quality partners for our customers from the national and international automotive industry", Steffen Modes explains the philosophy of the supplier company.
Fully automatic robot systems determine automotive welding and assembly line. In one area, a robot is responsible for handling boot lids. Here, unpredictable downtime had occurred time and again in the past, as the dress pack assembled on the robot by the factory did not withstand the cramped conditions on site. It got caught, got stuck and kept tearing off. "On average, the entire plant was down for 657 minutes per year. That resulted in costs of more than EUR 100,000 annually. In the long run, that was not acceptable", emphasises Steffen Modes, "so we were increasingly looking for a remedy." “
The robot services eight different stations in the plant. It picks up individual parts very precisely in the devices, guides them towards other devices before stacking the boot lids in two container towers. "For setting down, we are talking of collision values of at most 3cm", Modes explains the extremely tight spatial conditions on site. Hence, the most important requirements regarding the energy supply system are corresponding. The energy chain system has to feature very high tensile strength and very low weight. At a fast acceleration of 0 to 2m/s, it also has to withstand very high forces. Furthermore, environmental conditions are extremely adverse; there is a lot of welding dust.
Energy supply systems from igus GmbH, Cologne, Germany, have been in use since spring 2008. The project uses the triflex RS system, a compact universal module in which energy chains are guided in a space-saving way parallel and close to the robot arm. It can be installed easily and quickly on all existing mounting points on the robot, regardless of whether it is on the side or on top. Thanks to its very low installation height and slender chain guidance, the triflex RS energy supplies allow for all robot movements to be performed reliably even in the tightest installation spaces.
The grease-free energy chain system has an integrated retraction spring. By using fibre-rods that are stuck in fibre-rod modules, a directional pretension is automatically created. "These retraction mechanisms are similar to those of a fishing rod and always hold the energy chain on tension", explains Yve Kirsch, technical sales consultant in the igus office in Thuringia. "That way, the chain is always guided closely to the robot head, even with complex three-dimensional movements, so that there are no loops or cable stress." It cannot get caught on tools, the tool carrier or on other projecting edges.
"Altogether there were four problem robots, where we had to deal with extremely tight spatial conditions", Steffen Modes explains. "They were all equipped with the triflex R system by igus and don't cause trouble any more. The former plant stoppages are now a thing of the past, all robots have been running without any downtime for 18 months." Within a very short time, the investment had paid off.
Since the successful conversion, 1,380,000 cycles have been run. Shock-resistant, abrasion-resistant, tough and dirt-repellent: the four robots of the automotive supplier are equipped with the energy supply "triflex R", in the closed design "triflex TRC70". The energy supply ensures a high degree of flexibility for complex movements, even robot axis 6. Every chain link can be rotated along the longitudinal axis by approx. +/-10°. This facilitates cable routing around difficult geometric shapes.
The high tensile strength is enabled thanks to the so-called "trailer principle" (similar to the "ball/socket" mechanism). After locking, ball and socket constitutes an extremely moveable connection that combines smooth movements in all three axes with optimal traction, ensuring high tensile strength. A torsion of the longitudinal axis by +/380° per metre is possible. Both in radial and torsional movement, the triflex R energy supply offers a minimum bend radius that preserves cables due to its integrated stop-dog system.
Finally, the universal movability of the entire system enables fast teaching. Furthermore, this energy chain has very good mechanical properties. Shock-resistant, abrasion-resistant, tough and dirt-repellent it withstands the ever-present welding dust in rough industry use. Setup times are minimised due to the simple connection and suitable accessories, such as strain relief systems and clamps in this case.
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