From iron ore mining to... Steel rolling mill offers Mayr Antriebstechnik Pioneering safety clutches for the steel industry with high power density as well as high torques and speeds. Because where stones burst and hot steel steams, only robust, durable and solidly dimensioned couplings can cope with the extreme loads. And so also in the rolling mills of Arcelor Mittal can Couplings from Mauerstetten for maximum operational safety and maximum productivity.

Mayr steel production


With an annual production volume of around three million tons Steel and over 7500 employees, Arcelor Mittal Ostrava (AMO) is the largest steel producer in the Czech Republic and part of the world's largest steel and mining company Arcelor Mittal. The most important buyers of the steel, which is produced at several other production sites in the Czech Republic in addition to the plant in Ostrava, include the construction industry and mechanical engineering.

After the molten steel has been poured from the furnaces into plates, slabs, blocks or billets and thus shaped, these primary raw parts are further processed in the rolling mills and formed into finished steel products. In order to permanently protect the motor, gearbox and other drive components in the rolling stands from expensive overload damage, AMO relies on reliable ones EAS HT safety clutches of the drive specialist. The releasing clutches provide a non-destructive limitation of dangerously high torques and can easily withstand the harsh environmental conditions in steel production. They help to save material, manpower and costs and increase productivity in the rolling mills.

Exact torque limitation

Mayr20217Growing demand and the constant demand for more productivity demand top performance from rolling mills. Overload cases can never be completely avoided. Overload arises in the rolling stands, for example, due to a varying material consistency of the steel depending on the temperature and associated problems in the rolling process: for example if the material is not hot and therefore not soft enough and hits the rolling rolls.

Often even a single overload damage is much more expensive than a safety clutch. The investment in a clutch is therefore disproportionate to the costs that damage to a gearbox, for example, would entail both in terms of material costs and loss of production. That's why the steel manufacturer uses EAS-HT safety couplings in the rolling stands Powertrain reliably protect against damage. The couplings are in between Motor and Transmission and limit the torque exactly to the set value: The maximum torque is 170.000 Nm, the maximum speed is 400 rpm-1.

Protection at extremely high torques

“The releasing EAS-HT couplings are element couplings that are ideal for applications with very high torques and speeds or large moments of inertia,” explains Thomas Gebler, area sales manager at Mayr Antriebstechnik. “These couplings are based on individual overload elements that are integrated into the flanges. The achievable torque results from the preload force of the elements multiplied by the number of elements and the radius at which the individual elements are arranged.”


Orbit slip clutchSlipping clutch and overload clutch limit torques


Thanks to the modular concept, not only can clutches be built that are tailored to the respective application, but above all, significantly higher torques can be managed than with a central disengagement mechanism. To date, the company has produced safety clutches with a torque of 540.000 Nm delivered. But the limit is far from being reached: The modular design makes safety clutches with torques of several million Nm possible.

Function in case of overload

Mayr30217With the EAS-HT Element couplings The individual overload elements transmit the torque in a positive manner during trouble-free operation. In the event of an overload, they separate the drive and output in fractions of a second, with almost no residual torque, with high switch-off and repeat accuracy. Only the friction of the high-quality pressure flange bearing is effective. The kinetic energy of the rotating masses stored in the system can flow out freely. The element couplings remain separated until they are easily and quickly re-engaged by hand or using pneumatic, hydraulic, mechanical or electromechanical devices.

Release clutches The drive can withstand long stopping times after response. When defining the permissible stopping time, only the robust clutch bearing must be taken into account. Nevertheless, it makes sense to switch off and stop the drive as soon as the clutch has disengaged. The overload signal can be provided by a speed monitor or a non-contact limit switch that permanently monitors the operating status of the clutch. Due to the complete separation of input and output, no cogging shocks occur during the stopping time, which could have a negative effect on the drive train.

More precisely than break bolt couplings

“The EAS-HT safety couplings are now used in our rolling stands as a replacement for breaking pin couplings,” explains Karel Satke, Head of Mechanical Maintenance at Arcelor Mittal Ostrava. “The element couplings are designed in such a way that they can replace the shear pin couplings 1:1 in the short installation space. No changes to our application were necessary.” The releasing EAS-HT safety couplings work much more precisely than the breaking bolt couplings and are immediately ready for operation again after the cause of the overload has been eliminated.

Breaker pin couplings On the other hand, they have defined breaking points (breaking bolts) that break when overloaded and thus prevent damage to other components. However, after an overload, the destroyed components must be replaced. This causes costs and system downtime. In addition, the triggering torque is subject to relatively large tolerances: the breaking pin couplings lose transmittable torque over time because the breaking pins tire and therefore often separate too early, which in turn leads to unnecessary downtime. “The EAS-HT element couplings have been proving their worth in our systems for over a year now,” adds Karel Satke. “Since then there have been no more premature freakouts. The clutches disengage exactly when we need it. This enabled us to reduce downtime by over 80%. Snapping it back into place is now quick and easy.”

Before a coupling leaves the factory in Mauerstetten, it is tested extensively and adjusted exactly to the required value. Mayr also has a wide range of modern... Testing options and can rely on decades of experience in development and construction. An electronic database in which the measured values ​​are archived together with the associated serial numbers of a product ensures 100 percent traceability.

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