Posted by Dr.Andrey M. Weinov on March 05, 2004 at 03:37:14:
Novokramatorsky Mashinostroitelny Zavod has 65 years' experience in producing various types of roll and other equipment for rolling mills
In this period we have manufactured about a million and a half tons rolls for rolling mills which operate in more than 20 countries of the world.
More sophisticated facilities for iron and steel making and machine-assembly production divisions of NKMZ make it possible to manufacture products satisfying the high Consumer's requirements. Specifically, the after-furnace refining facility ensures particular purity of steel and the compound rolls manufacturing process brought out to a commercial level in the Company enables to provide their durability 3-4 times higher than the same of the rolls manufactured by the conventional technology.
NKMZ in cooperation with Paton Electric Welding Institute have constructed a fundamentally new equipment which realizes the process of production of new generation rolls-double-layer rolls with the operating layer of high-speed steel or high-chromium iron. The rolls are manufactured with the method of electroslag facing the operating surface layer with hot metal.
The secondary heat treatment of rolls is carried out in automated roller-hearth heat treating furnaces. In order to provide high level of physical and mechanical properties, the rolls are cooled by water and air-water mixture in special-purpose controlled cooling units.
During heat treatment operations the temperature is controlled by furnace thermoelectric couples and optical pyrometer produced by Wahl Company, USA.
NKMZ manufactured the equipment and realized the differential heat treatment technology for backup roll bodies. As a result of this process, the depth of case up to 70 mm is provided.
The roll bodies hardening is executed in the automated induction hardening facility with induction heating. This provides recurrence of the hardening results. Hardness variation does not exceed 2-3 HSD. The work rolls have the depth of the effective case up to 45 mm, the backup rolls - up to 60 mm along the radius.
To harden the necks for the bodies hardness of 45 HSD the technology of hardening with high-frequency heating is introduced in the Company.
By estimation of specialists from the leading machine-building companies and iron and steel works, the use of compound rolls is one of the main trends in the field of iron and steel industry development since they have a substantially longer service life and provide manufacture of high-quality rolled products.
The quality of the rolling-mill rolls as well as CCM rollers which are manufactured at Novokramatorsky Mashinostroitelny Zavod has been attested with the certificates issued by the Technical Supervisory Company TÜV NORD, Germany.