Superconductors for resource-efficient industrial automation
Festo is currently conducting research on superconductor technology and is presenting applications for automation technology for the first time in Hanover
Superconductors work by hovering, are resistance-free and energy efficient. While they have been used in medical technology for two decades and are currently making their mark in large-scale systems with high power density, Festo is looking into how the technology can be applied to sustainable production of the future. Smaller-scale applications in the field of frictionless, hovering bearing systems are interesting for production systems. Festo is showcasing the potential of superconductor technology and the research topics for automation technology at the Hanover Trade Fair 2013 with three exhibits developed in cooperation with evico and other partners from research and academia.
Superconductors are metals, metal compounds or ceramic materials which abruptly enter a superconducting state below a certain transition temperature. When this happens, they lose their electrical resistance. “Once the transition temperature is reached, mutually repulsive electrons bind to form what are called Cooper pairs. Once paired, they can no longer interact with the atomic lattice that surrounds them, and as a result conduct the electrical current without any resistance,” explains Prof Dr Werner Hanke from the University of Würzburg. “Once the electrical current is put into motion in the superconducting material below the transition temperature, it flows in a closed circuit without any losses,” adds Prof Dr Hanke.
The superconductor technology is still in the research stage but has great potential in material development and cooling systems. The cost of cooling the material to extremely low temperatures stood in the way of widespread industrial applications for a long time. “High-temperature superconductors whose transition temperature is above 100 Kelvin were discovered in 1986. These superconductors are ceramic materials. Since then, it has become possible to cool materials directly using liquid nitrogen or electrically, which is much cheaper and more practical,” explains Prof Dr Ludwig Schultz from the Leibniz Institute for Solid State and Materials Research (IFW Dresden).
Superconducting magnetic bearings in automation
If a superconductor is cooled to below the transition temperature under the influence of the external magnetic field of a permanent magnet, not only does it lose its electrical resistance but it also changes its characteristics: the superconductor can store the magnetic field of the permanent magnet at a predefined distance and enable a stable hovering condition. The superconductor responds to any attempt to move it by returning to the stored position. The three research projects demonstrate this characteristic of frictionless, stable bearing without the need for complex measurement and control technology.
SupraLinearMotion – hovering thanks to superconductivity
SupraLinearMotion, a rocker with a seat for one person, brings superconductor technology to life for the trade fair visitors. To make the rocker hover, the superconducting material on the bottom of the slide is passively cooled to a constant temperature between 63 and 77 Kelvin using liquid nitrogen. It is then placed approx. 15 millimetres above a rail, a simple magnetic guideway made of permanent magnets. The material stores and maintains the defined position parallel to the rail. To move the slide, the rocker is taken off balance. As soon as the downward movement starts and the rocker tips over, gravity takes over. The passenger floats on the rocker, carried by superconductance.
SupraHandling – frictionless movement in a level plane
This principle has been transferred to an X/Y-table for moving objects in a level plane. Two drives attached beneath the table tilt the base plate in the X and Y direction independently from each other. By doing so they set two slides that hover on magnetic rails in motion without touching them. This means that for the first time, the slides of an X/Y-table are moving on superconducting bearings. As with SupraLinearMotion, the superconductor in this handling system is passively cooled using liquid nitrogen. The distance and position relative to the magnetic rail is maintained and stable hovering becomes feasible. There are many possible applications of this technology in automation. For example, characteristics such as freedom from noise, freedom from wear and the ability to maintain a defined distance open up new applications for automation technology. The soft suspension and the low energy expenditure enables gentle movements without any additional expenditure.
SupraPicker – handling system in an hermetically sealed room
The SupraPicker exhibit shows a magnetic gripper with superconducting bearing system which completes a two-part handling operation, first outside an hermetically sealed room and then inside this room. The gripper, which hovers thanks to superconductivity, picks up a vial magnetically, conveys it through a lock into an hermetically sealed room and places it in the designated position. The exhibit showcases the benefits of the non-contacting, stable, superconducting bearing system, which opens up new opportunities for handling applications. Once the magnetic field is stored, the magnet that performs the gripping function and the superconductor can be physically separated without any problems – for example, by a plexiglass wall as in the exhibit. In this application, the superconducting material is actively cooled by a small, electric cooling unit. This does away with the need for auxiliary units for cooling, transporting and storing liquid nitrogen, which makes potential industrial use much easier.
You will find Future Concepts exhibits from Festo at stand D07 in hall 15.
Further information can be found at: www.festo.com/bionics
Full article with pictures: www.festo.com/press
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Festo AG & Co. KG
Julia Duwe, head of Corporate Communication – Technology
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