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Our rolling mill for rock drill steel for the manufacturing of top-hammer rock drill rods is the most up-to-date in the world. This unique mill is fully automated and designed specifically for manufacturing this one product.
After rolling in the billet mill, the rods are turned to avoid decarburization in the final rolling process. A long, straight center hole is drilled in the drill steel blank and a core is inserted in the hole before heating the blank. The blanks are hot-rolled into round or hexagon-shaped drill steel.
A carefully controlled cooling process after rolling guarantees uniform mechanical properties. The core is removed and, after the finishing operations, the drill steel is ready for shipment.
The size range is from 19 mm (0.748 in.) hexagon (width across flats) to outside diameter (OD) 60 mm (2.362 in.) round.
The hollow drill steel is straightened after rolling in a roller straightening machine.
Cutting of random lengths or cutting into fixed lengths. The hollow drill steel is free from burrs.
On customer request, hollow drill steel, especially for overseas markets, is oiled and the holes are plugged as a means of corrosion protection.
The hollow drill steel is bundled and each bundle is identified by tagging. The marking is normally a standard marking, but can also be made according to customer request.
Hollow drill steel from Alleima is tested according to customers' specifications.