A research group led by Ri Yong Min, a researcher at the Faculty of Materials Science and Technology, has developed a screw rolling mill with individually driven rollers and established a rolling process which can produce bars of more than 20mm in diameter through one pass without a roller change from round steel of 50mm in diameter, consuming less power. They will no longer need an ordinary light section rolling mill in machine factories and repair bases that have a great demand for bars in various diameters.
In this rolling process, round steel of 50mm in diameter is heated to 850~950℃ in a heating furnace and is rolled into bars of 20mm in diameter through one pass in a cantilevered 3-helical rolling mill with individually driven rollers that has a large feed angle and an elongation angle before they are cut into necessary lengths.
Thus, they can produce bars of different diameters from short scrap iron by changing no rolls but adjusting the roll gap, and ensure the metal yield of more than 99% and the roundness of ±0.1.
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