Authors: S.E. Lundberg, M. Allen
AISTech 2009 on May 5, 2009
Abstract
In the second half of the 20th century important developments were made in special steel bar and wire rod rolling. Since the early ideas of Erik Norlindh in the late 1940’s concerning automatic mechanized rolling, cartridge stands, roller guides, pre set stands and the ready to roll concept, wire rod and bar rolling technology has developed to a highly automated process. The productivity of modern mills is in orders of magnitude higher than mills at the end of World War II.
Speeds up to 40 m/s are not uncommon for bar rolling. However, in special steel rolling where the speed usually is lower, it is common to separate the rougher from the intermediate and finishing mills either by a free continuous breaking down mill, or by a reversing rougher. This is because low speeds in the roughing stands of fully continuous mills create surface defects due to overheating of the roll surface, which gives deep fire cracks that get printed on the bar and especially due to “overcooling” of the bar surface, which creates cracks during the deformation.
