Abstract: A continuous mill plant for rolling steel plates having one or a plurality of rolling mills. The ratio of maximum rolling speed to minimum rolling speed of the plant is at least 3.0 but no more than 10.0 at the continuous rated output of an electric motor for driving the rolling mill.

Abstract: A cold-rolled strip manufacturing apparatus, in which a continuous cold reduction mill and a continuous annealing furnace are directly linked together, has a tension-leveller-type scale breaker for elongating hot-rolled breakdown by 2 to 7 percent, a scale scrubbing brush unit and an immersion-type continuous pickling tank installed upstream of the continuous cold reduction mill.Descaling of the hot-rolled strip coil is carried out by breaking the mill scale formed on its surface by causing the running strip to elongate and then the broken scale is removed from the surface. The percent elongation given to the strip is feedforward controlled on the basis of the manufacturing conditions of the hot-rolled strip coil and/or the properties and quantity of the mill scale formed. In another descaling method, the percent elongation given to the strip is feedback controlled on the basis of the condition of scale breaking and removing that is detected during the period in which the mill scale is broken and removed.

Abstract: A roll-changing apparatus for use with a rolling machine including a roll-changing truck, a roll-exchanging truck, a roll-setting truck and a roll rack facility which are used to transport sets of rolls in conjunction with one or more racks having vertically spaced-apart sets of rails for supporting and transferring the rolls. The rolls can be transferred by sliding them between individual racks mounted on each of the roll-changing truck, the roll-exchanging truck and the roll rack facility or a single rack can be rolled from the roll rack facility to the roll-exchanging truck and then to the roll-changing truck for transferring the rolls to and from the rolling machine. The roll-setting truck includes a set of vertically movable rails for aligning with a respective set of rails of a rack mounted on the roll rack facility. The roll rack facility includes a plurality of racks, each of which holds a set of used or reconditioned rolls.

Abstract: In a cooling zone of a continuous annealing line engineered to continuously process longitudinally travelling steel strip, the strip is first slowly cooled to a desired temperature at a rate of not higher than 20.degree. C./sec. by means of a jet stream of cooling gas ejected against the surface of the strip and subsequently quenched to a desired temperature at a rate of not lower than 70.degree. C./sec. Thinner strip is quenched by high-speed gas-jet cooling that is effected by ejecting a jet stream of cooling gas against its surface, while heavier strip is quenched by bringing it into contact with the perimeter of cooling rolls cooled by a coolant. Namely, quenching is achieved either by high-speed gas-jet cooling or roll cooling depending on the thickness of the strip being processed.

Abstract: A strip cooling apparatus for a continuous annealing furnace for continuously treating longitudinally fed steel strip has a pair of cooling gas chambers attached to the furnace walls on both sides of the strip so that the front of each chamber faces the strip. Each cooling gas chamber has nozzles having round outlets opening toward the strip surface on its front side to shoot forth a cooling gas jet against the strip furnace. The nozzle is separated from the strip by a distance z not larger than 70 mm and projected from the front of the cooling gas chamber by a length of not less than (100--z) z) mm. The cooling apparatus also has a pair of rotatably holding rolls reciprocatably attached to the furnace walls to press the strip at a right angle thereto. The holding rolls holds the strip and prevents the occurrence of fluttering.

Abstract: Steel strip is continuously annealed while successively travelling through a heating, soaking, primary cooling, overaging and secondary cooling zone in an annealing furnace. In the overaging zone, an endless steel strip is allowed to run through a passageway that extends spirally from the entry end of the overaging zone to the point where overaging is completed, at a given distance in the direction of radius. The guide strip travels at the same speed as the steel strip being processed that is delivered from the primary cooling zone. On the entry side of the overaging zone, the strip being processed is laid over the guide strip so that the two strips spirally travel through the overaging zone side by side. The processed and guide strips running together are shifted out of the spiral passageway at the point where overaging is completed. Then, the processed strip is separated from the guide strip by shifting at least one of the two strips.