Abstract: A rolling mill comprising a roll unit and a drive unit for driving the roll unit. The drive unit comprises an outer housing, a pair of large-diameter ring-like driving bevel gears disposed concentric with the pass line, an input shaft mechanism for rotating the driving bevel gears, and transmission mechanisms for transmitting the torque of the driving bevel bears to the rolls. Each transmission mechanism comprises a small-diameter transmission bevel gear caught between and engaging with the driving bevel gears and first and second transmission shafts for transmitting the torque of the transmission bevel gear to a roll. The drive and roll units are coupled and uncoupled by couplings. Four positioning parts are formed on the outer periphery of the inner housing of the roll unit. The outer housing of the drive unit is generally in the shape of a ring, and four positioning parts are formed on the inner periphery of the outer housing.

Abstract: A method of controlling the operation of a cross helical rolling mill. The cross helical rolling mill has a pair of work rolls arranged at respective predetermined lead angles, and a pair of power-driven drive roller shoes arranged obliquely at predetermined lead angles on both sides of the rolling region formed between both work rolls. The method comprises controlling the rotation speed of each of the drive roller shoes in synchronism with the speed of rotation of the rolled material such that the difference in the peripheral speed between each of the drive roller shoe and the rolled material falls within a predetermined range, and, simultaneously with the control of the speed, controlling the driving torque applied to each of the drive roller shoes.

Abstract: In order to enhance the CO concentration contained in exhaust gas generated during the refining of metal and to recover the CO as an energy source, granular limestone is blown into molten iron containing at least 0.3% of carbon through a tuyere together with a refining gas, and CO.sub.2 generated by the decomposition of the limestone is reacted with carbon contained in the molten iron to form CO, and the resulting CO is recovered.