Abstract: The hot rolling apparatus of the present invention has a mill arranged on the preceding stage, mills of a plurality of stands arranged on the later stage which are different-diameter roll mills including a pair of different-diameter work rolls having an equivalent roll diameter of less than 600 mm or minimum-diameter roll mills including a pair of work rolls having a diameter of less than 600 mm, and a cooling unit for cooling steel to be rolled which is arranged on each exit side of the mills of at least two stands on the later stage. The hot rolling apparatus can smoothly manufacture hot rolled plates of fine-particle steel.

Abstract: A sheet rolling method uses a rolling mill (10) for rolling a sheet (x). The rolling mill (10) includes upper and lower backup rolls (13, 14), and a pair of work rolls (11, 12) respectively having different diameters and disposed between the upper and the lower backup roll (13, 14). A small-diameter work roll (11) of the pair of work rolls is disposed so that a rotational axis thereof is positioned on a mill center or a downstream side with respect to the mill center in a rolling direction, and the large-diameter work roll (12) is disposed so that a rotational axis thereof is positioned on a downstream side with respect to the rotational axis of the small-diameter work roll (11) in the rolling direction. Thus, mechanical load on the work rolls (11, 12) can be reduced even when a high rolling force is necessary for rolling a wide sheet.

Abstract: The hot rolling apparatus of the present invention has a mill arranged on the preceding stage, mills of a plurality of stands arranged on the later stage which are different-diameter roll mills including a pair of different-diameter work rolls having an equivalent roll diameter of less than 600 mm or minimum-diameter roll mills including a pair of work rolls having a diameter of less than 600 mm, and a cooling unit for cooling steel to be rolled which is arranged on each exit side of the mills of at least two stands on the later stage. The hot rolling apparatus can smoothly manufacture hot rolled plates of fine-particle steel.

Abstract: A sheet rolling method uses a rolling mill (10) for rolling a sheet (x). The rolling mill (10) includes upper and lower backup rolls (13, 14), and a pair of work rolls (11, 12) respectively having different diameters and disposed between the upper and the lower backup roll (13, 14). A small-diameter work roll (11) of the pair of work rolls is disposed so that a rotational axis thereof is positioned on a mill center or a downstream side with respect to the mill center in a rolling direction, and the large-diameter work roll (12) is disposed so that a rotational axis thereof is positioned on a downstream side with respect to the rotational axis of the small-diameter work roll (11) in the rolling direction. Thus, mechanical load on the work rolls (11, 12) can be reduced even when a high rolling force is necessary for rolling a wide sheet.

Abstract: Disclosed is a lubricating composition for hot-rolling steel, which comprises a base oil or base grease and a heat-insulating agent. Especially, (A) an inorganic compound which is melted by an absorption of heat at a temperature lower than 1200.degree. C. and (B) an inorganic powder which is not melted or decomposed at a temperature lower than 1200.degree. C. and has a heat conductivity lower than 0.01 cal/cm.s. .degree.C. at room temperature and a friction coefficient smaller than 0.7 are incorporated in specific amounts singly or in combination in the composition. This lubricating composition has an excellent heat-insulating effect and effectively prevents the thermal crown of a work roll.