Energy chains from igus safely guide cables and hoses in Mikromat’s robotic machining systems
Mikromat in Dresden has an excellent reputation worldwide as a manufacturer of robotic machining systems that mill and grind very large components with micrometre accuracy. The machine manufacturer uses igus E4.1 series energy chains to supply energy, signal and media to the spindle. The chain, including options, is designed individually for each machine.
There are not many industrial companies that need to machine and deliver ten-metre-long components with an accuracy of less than 0.01 mm. Those who do will know the machine range of the Mikromat GmbH in Dresden. Mikromat is one of the very few manufacturers in the world who develop and manufacture machine tools for the precision machining of large components. The extremely high precision applies not only to the dimensions of the workpieces, but also to their straightness and squareness, which is already achieved by the basic design – that is, without electronic correction.
At the same time, the machines reach impressive dimensions. Even the smallest linear robot system, the Mikromat 8 V, is really large with a clamping area of 1000 x 800 mm (optionally 1000 x 1500 mm) and a space requirement of 6.50 x 4.50 x 3.90 m. The largest of the linear robot systems with the designation 40 V weighs 220 tons with a space requirement of 36.80 x 10 x 9 metres.
Drilling and milling in the micrometre range
All linear robot machines – from the 8 V to the 40 V – of the company with a history dating back to 1863, are suitable for drilling, grinding and milling in the micrometre range (Fig. 1). The 40 V achieves a machining accuracy of 5 μm with a component length of up to 13.70 m. Their two workpiece tables can be used alternately to shorten set-up time. But you can also process synchronously to machine very large components.
A sophisticated weight balance of the drives contributes to the maximum positioning accuracy of the traversing axes, as well as the thermal management: Assemblies vital to accuracy are configured in thermal symmetry. The production takes place in tempered halls.
Who needs such a high machining accuracy? The CEO Dipl.-Ing. Thomas Warnatsch: “We design and manufacture such systems, for example, for manufacturers of large gearboxes, engine components and other aviation components.”
Energy chains are core components
As in any machine tool – regardless of size and precision – Mikromat’s V series spindles also need to be supplied with energy, signals and media such as coolant and compressed air via moving cables. These cables are routed in energy chains from the E4.1 series (Fig. 2). Mikromat uses the enclosed tube option, which prevents the ingress of dust and swarf.
From the designer’s point of view, energy chains are core components of the machines. Dipl.-Ing. (FH) Daniel Weitzmann, Design/Development: “They must be smooth and reliable. And as visible parts, they should also look good.” The igus energy supply system fulfils these requirements: “The chain has always lived up to our expectations.” One reason for this is the robust construction: the “undercut design” of the individual chain links ensures, for example, the required lateral stability during high lateral acceleration of the axes (Fig. 3).
Good cooperation in the project planning
Great care is taken in the design of each individual chain in Mikromat. Daniel Weitzmann: “We have developed a basic design for each machine, which also uses different installation situations of the chain – vertical, horizontal, gliding. For each new machine we develop, we send the application data such as travel distances and travel speeds, filling and minimum bend radii to igus and based on them we receive the design of the chain and the connection. This also includes the arrangement of the media in the chain and the selection of connectors.”
Mikromat basically constructs the machines tailored to a customer’s specific needs and thereby implements the individually desired options, which can also have an impact on the design of the energy chain. For example, Mikromat recently delivered a linear robot system with elaborate air extraction. The extraction hose is carried on the chain, attached via an extender crossbar. This solution is a standard option of the E4.1 series from igus, so that the designers were able to use familiar chain types .
Designed and built for a long machine life
The machines are designed not only for the highest precision but also for a very long service life. Daniel Weitzmann: “The configuration only settles fully after six months. Then the geometry is corrected. And with proper care you can even pass on the machines to the next generation. Especially since all the essential parameters are adjustable.” Accordingly high are the requirements on the service life of the moving energy supply systems: it should extend up to ten years. And this is also achieved without problems. This also applies to the cables. They come from the igus chainflex product range. In addition this applies to the connection plates, which stem from Mikromat’s own design and are strong as well as easy to assemble and maintain.
igus catalogue at hand for the design
Mikromat is designed according to the principle “one machine – one designer”. So there is not one specialist in energy chains, and the task is complex: a typical circuit diagram has around 700 pages. The assembly can influence the design. Daniel Weitzmann: “We also keep the igus catalogues for the assembly, so that the employees can find the best solution. For example, they recently tried a pivoting mounting bracket that they chose. The company igus sent a sample of this component very quickly.” In short, Mikromat’s designers are very satisfied not only with the energy chains, but also with the service and support provided by igus. Now, three-dimensional triflex R chains from the igus product range are also being used in a different product line of the company – high-precision machines for rotational moulding and thread grinding.
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