Super-cooled design halves energy consumption of induction heaters.
German based Trithor, a leader in the production of high temperature superconducting (HTS) systems, has applied its technology to the production of a new generation of non-ferrous induction heaters with shorter heating times and superior efficiency.
Trithor’s HTS induction heater, available in sizes between 0,25 and 2 MW, revolutionises aluminium, copper and brass billet heating prior to extrusion, cutting energy demand and operating costs to almost half, since there are virtually no electrical losses.
Conventional AC induction heating has an efficiency of around 45%, with heat being dissipated in both the coil and the billet. The Trithor design differs in two crucial ways. The induction coils are manufactured out of the advanced HTS material, chilled with compact machine-mounted chillers to 30°Kelvin (-250°C) and carry high DC current, with virtually no losses. To create the induction heating effect, the billet is rotated in the powerful electromagnetic field – the speed profile being determined by the size of billet and type of material.
The rotation is controlled by two 132 kW Unidrive SP AC drives, one at each end, in closed loop control and with feedback from 1024 ppr absolute encoders. Rotation is opposed by torque, generated by the magnetic field, precise synchronism of both speed and torque being essential. This is monitored and controlled by the software in the intelligent option modules fitted to each drive.
“Precise synchronism of the motor speeds is crucial, particularly as the billet is approaching its elastic state,” says Trithor’s head of sales, Dr Jürgen Kellers. “The controlled rotation gives more even billet heating, enabling us to produce the best possible radial homogeneity of temperature by improved deep heating inside the component. At the same time it allows precise and repeatable speed, time and temperature profiles to be set up, giving the customers levels of quality control not previously achievable.”
As well as improving operating efficiency from 45% to over 90% the Trithor HTS induction heater requires less maintenance and has an extended working life as it carries no conventional thermal loads. For the same reason, tool changing is faster and safer. Machines with dual head heating chambers can be provided for even greater productivity.
The Unidrive SP AC variable speed drive range spans 0,75 kW up to 1,9 MW. Unidrive SP is an ‘advanced solutions platform’ AC drive, configurable in five operating modes: open and closed loop; vector; servo and regenerative. Connectivity to most industry standard networks is available with 14 position feedback protocols and configuration for all types of AC motors. Utilising the range of plug-in options allows the onboard PLC to be supplemented, as in this case, with an additional programmable module.
“Control Techniques has been involved right from the initial development stage in this and other projects. We like the flexibility and programmability of the Unidrive SP drives, which are ideal for all types of motors, including asynchronous linear motors used in direct drive applications such as our new Limodraw contactless tube drawing machines,” concludes Kellers.
A key element of these unique machines is the rotation of the work-piece: The technology partner in this advanced venture – Control Techniques.
For more information contact Bill Tedd, Control Techniques, +27 (0)11 462 1740, [email protected], www.controltechniques.com
| Tel: | +27 11 462 1740 |
| Fax: | +27 11 462 1941 |
| Email: | [email protected] |
| www: | www.controltechniques.com |
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