Flexible couplings take on the rigours of the steel mill
02 August 2012
The installation of a 154m long hot strip runout table at a steel mill near Budapest, Hungary, required the installation of nearly 350 power transmission couplings to ensure reliable and continuous transportation of hot steel billets around the plant.
These couplings have to cope not only with the high temperatures associated with steel manufacture, but also the contaminants that are present within a steel processing environment. And in view of the numbers of couplings involved, easy installation and maintenance were deemed essential.
The runout table is equipped with 337 1.8m wide, 300mm diameter, stainless steel rollers, driven by 7.5kW motors at 900rpm. Ultimately, it is expected to increase the mill’s throughput from the present 1.8 million tons to 3 million tons per annum.
The specification called for each roller drive to be equipped with an extremely low maintenance coupling that would be capable of transferring the motor torque efficiently, regardless of the adverse environmental conditions, while also being able to cope with a small degree of misalignment. Following a trawl of the market, the mill operator decided on the DuraFlex coupling from TB Wood, a company within Altra Industrial Motion’s industrial couplings division. Altra divisional director, David Proud takes up the story:
“We were approached by the steel mill and asked if we could recommend a product that would function reliably at the heart of its production site. Steel mills are a notoriously harsh environment for any component. The runout table was to be responsible for transferring over 8,000 tons of steel every day; any failure would have created a bottleneck, slowing production and ultimately proving very costly.”
The flexible polyurethane element of the DuraFlex coupling transfers torque via the driven shaft to the rollers while accommodating misalignment and providing a degree of vibration damping to protect connected equipment. The area where the flexible element is bonded to the shoe of the coupling is the result of a design exercise involving finite element analysis software, and has thus been optimised to prevent any possibility of failure. This is a patented feature of the DuraFlex range.
Another DuraFlex design feature is its ‘split-in-half’ arrangement, which facilitates easy element installation and replacement without having to move connected equipment or disturb the shaft connection. In the event that a roller needs maintenance, or the couplings need replacing, this design feature ensures that such a task can be accomplished easily and speedily. David Proud again:
“We were happy to be able to help the steel mill almost double its annual production facilities. We try to listen to the needs of our customers and tailor our service to their specific requirements. In this case they needed the couplings at very short notice; we were able to reduce our normal lead time of eight weeks down to four to meet with their required deadline.”