There is provided a zigzagging control method for a workpiece including: an estimation step of, before rolling of a tail portion of the workpiece, acquiring at least any one of an inter-roll thrust force estimated based on an inter-roll cross angle and an inter-roll friction coefficient and a material-roll thrust force estimated based on a material-roll cross angle and a material-roll friction coefficient; and a tail control step of, during the rolling of the tail portion of the workpiece, measuring work-side and drive-side rolling loads, correcting a rolling load difference or a rolling load difference ratio based on any two of acquired parameters including a roll-axis-direction thrust counterforce at the measurement of the rolling loads, the inter-roll thrust force, and the material-roll thrust force, and performing reduction leveling control on a rolling mill based on the corrected rolling load difference or rolling load difference ratio.

A method for rolling a rolling material in a rolling mill comprising at least one roll stand. A gap height of a rolling gap arranged between working rolls of the roll stand is set to be smaller than an in-feed thickness of the rolling material before contact of the rolling material with the working rolls. At least one driven working roll of the roll stand is driven at a desired rotational speed once the rolling material has reached the rolling gap, and the driven working roll is operated at a feed-forward rotational speed deviating from the desired rotational speed, until the rolling material reaches the rolling gap.

A method for rolling a rolling material in a rolling mill comprising at least one roll stand. A gap height of a rolling gap arranged between working rolls of the roll stand is set to be smaller than an in-feed thickness of the rolling material before contact of the rolling material with the working rolls. At least one driven working roll of the roll stand is driven at a desired rotational speed once the rolling material has reached the rolling gap, and the driven working roll is operated at a feed-forward rotational speed deviating from the desired rotational speed, until the rolling material reaches the rolling gap.

The disclosure relates to a method for controlling a stretch-reducing mill. Tube ends of stretched tubes are optimized by controlling one or more motors of the stretch-reducing mill. The method includes at least one outlet-side wall thickness measurement and an automatic adjustment of the value of a speed change of the motors to the tube wall thickness profile. The progression of the speed changes over time of individual or all motors is also automatically adjusted on the basis of the tube wall thickness measured values.

The present invention relates to steel for pressure vessels used in a boiler, a pressure vessel fittings, etc. of a power station and, more particularly, to steel for pressure vessels with excellent resistance to high-temperature tempering heat treatment and post-weld heat treatment; and a manufacturing method therefor.

A hot-rolled steel sheet not exceeding a coil opener allowable load during unwinding includes a steel sheet cut in unsteady portions at its longitudinal head and tail ends in a cutting step after a rough rolling step, having a width of 1,200 mm to 2,300 mm, a thickness of 13 mm to 25.4 mm, and at least an API standard X65-grade strength, and used in a state of being unwound after having been wound around a coil. A longitudinal end corresponding to the unwinding start includes a portion at its widthwise center recessed inwards in the longitudinal direction with respect to its two widthwise ends, the two widthwise ends projection sizes with respect to the recessed portion at the widthwise center are 20 to 295 mm, and the sum of the widths of projecting portions at the two widthwise ends is set to to of the sheet width.

A method for rolling a rolling material in a rolling mill comprising at least one roll stand. A gap height of a rolling gap arranged between working rolls of the roll stand is set to be smaller than an in-feed thickness of the rolling material before contact of the rolling material with the working rolls. At least one driven working roll of the roll stand is driven at a desired rotational speed once the rolling material has reached the rolling gap, and the driven working roll is operated at a feed-forward rotational speed deviating from the desired rotational speed, until the rolling material reaches the rolling gap.

A method for rolling a rolling material in a rolling mill comprising at least one roll stand. A gap height of a rolling gap arranged between working rolls of the roll stand is set to be smaller than an in-feed thickness of the rolling material before contact of the rolling material with the working rolls. At least one driven working roll of the roll stand is driven at a desired rotational speed once the rolling material has reached the rolling gap, and the driven working roll is operated at a feed-forward rotational speed deviating from the desired rotational speed, until the rolling material reaches the rolling gap.

A Steckel mill has a reversing unit for rolling a rolled product and winding furnaces arranged on the entrance side and exit side of the reversing unit. When rolling the rolled product in a region of a head of the rolled product, a target thickness of the rolled product is ignored, while measuring a current thickness and/or a hardness of the rolled product and comparing this with a setpoint value. One the measured variable reaches or is below the setpoint value, the reversing unit is operated with a view to achieving the target thickness of the rolled product. The Steckel mill is operated to allow for rolling of a cold, non-rollable piece of the rolled product, so that malfunctions are avoided and the usable part of the rolled product is as large as possible.

A Steckel mill has a reversing unit for rolling a rolled product and winding furnaces arranged on the entrance side and exit side of the reversing unit. When rolling the rolled product in a region of a head of the rolled product, a target thickness of the rolled product is ignored, while measuring a current thickness and/or a hardness of the rolled product and comparing this with a setpoint value. One the measured variable reaches or is below the setpoint value, the reversing unit is operated with a view to achieving the target thickness of the rolled product. The Steckel mill is operated to allow for rolling of a cold, non-rollable piece of the rolled product, so that malfunctions are avoided and the usable part of the rolled product is as large as possible.