Drive device for roll stands

Details Drive device for roll stands Drive device for roll stands

1999-02-04

2001-02-20

Tolan, Ed (Department: 3725)

Metal deforming

With use of control means energized in response to activator...

Metal deforming by use of roller or roller-like tool element

C072S029100, C072S249000

Reexamination Certificate

active

06189352

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a driving arrangement for rolling stands having an air-cooled converter.
BACKGROUND INFORMATION
It is known to design self-commutated converters for drives of rolling stands in a water-cooled fashion. Such designs, however, are expensive to produce and maintain.
SUMMARY OF THE INVENTION
It is the object of an present invention to provide a converter for drives of rolling stands which, in contrast with conventional converters in this power range, can be produced more easily.
It is also an object of the present invention to provide a converter for drives of rolling stands which, in contrast with conventional converters, is simpler and more cost-effective to operate and maintain.
The object is achieved according to the present invention by providing an air-cooled converter. Previously, air cooling was believed to be unsuitable for converters for drives of rolling stands which, in particular, are operated in a power range of 1 to 20 MW. However, it has proved that converters can be designed with air cooling in the power range designated above. In this case, by contrast with known water-cooled converters in the above-named power-range, such air-cooled converters have proved to be particularly cost-effective and easy to maintain.
In an advantageous embodiment of the present invention, heat sinks electrically connect individual turn-off power semiconductors. This electrical connection likewise represents a good thermal connection, with the result that the heat occurring in the power semiconductors is adequately dissipated. In this case, it has further proved to be advantageous to use heat sinks having such a high thermal capacity that the heat sinks react thermally with a time delay in the case of peak loads.
The driving arrangement according to the present invention is suitable, in particular, for converters having low operating frequencies. In the case of converters in a three-point circuit such as is shown, for example in
FIG. 6
, the drive system according to the present invention is used with particular advantage in the case of mean operating frequencies of the converter <250 Hz. In driving arrangements having a motor in a tandem connection, the drive system according to the present invention is suitable in a particularly advantageous fashion for mean operating frequencies <100 Hz.
In a further advantageous embodiment of the present invention, the converter has a blower which feeds ambient air or precooled air to the heat sinks, or advantageously sucks ambient air through the heat sinks.


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D. W. Draper et al., “Thyristor-Supplied Tandem Cold Mill”, Proc. IEEE, vol. 115, No. 10, Oct. 1968.
L. Bala Krishnan, “Economic Factors Governing the Specification and Selection of Electrical Equipment for Large Reversing Drives in Rolling Mills,” ASEA Journal 1973, vol. 46, No. 4.
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*G. Fischer et al., “Design and Operational Behaviour of Air Cooled High Power 3-Level-Inverter with Reverse Conducting GTOs,” Power Conversion, May 1996 Proceedings.

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