Abstract: Adhesive matter remaining at the end of a cuboid metal material is reliably removed in a relatively short time while suppressing the decrease in yield rate of the metal material. Distances of the upper surface and the lower surface of a cuboid metal material from a reference position are measured using a distance measurement device in the longitudinal direction of the slab including the longitudinal end of the slab. On the basis of the measurement results, the state of remaining of adhesive matter remaining on the upper and lower surfaces of the longitudinal end of the slab is comprehended. On the basis of the state of remaining of adhesive matter, the amount and position of cutting by a cutting tool is determined. Corner removing cutting is performed on the upper and lower surfaces of the longitudinal end of the slab using the cutting tool in accordance with the determined amount and position of cutting.

Abstract: A rail cooling device configured to forcibly cool a rail by jetting a coolant includes a porous plate nozzle including a plurality of nozzle holes configured to jet the coolant to an underside of the base of the rail to cool the underside of the base of the rail. Ends in a width direction of the porous plate nozzle correspond to ends of the underside of the base of the rail. Nozzle holes of the porous plate nozzle at the ends of the width direction are smaller than nozzle holes of the porous plate nozzle at a central part in the width direction, and a maximum value of a distance between centers of the nozzle holes at both ends in the width direction is 30% or more of a width of the underside of the base.

Abstract: A rail cooling device configured to forcibly cool a rail by jetting a coolant includes a porous plate nozzle including a plurality of nozzle holes configured to jet the coolant to an underside of the base of the rail to cool the underside of the base of the rail. Ends in a width direction of the porous plate nozzle correspond to ends of the underside of the base of the rail. Nozzle holes of the porous plate nozzle at the ends of the width direction are smaller than nozzle holes of the porous plate nozzle at a central part in the width direction, and a maximum value of a distance between centers of the nozzle holes at both ends in the width direction is 30% or more of a width of the underside of the base.

Abstract: A rail cooling method for forcibly cooling a rail by jetting a coolant includes jetting the coolant to a foot back part of the rail from a porous plate nozzle in which a nozzle hole at an end in a width direction is smaller than a nozzle hole at a central part in the width direction and causes a cooling capacity for the end in the width direction of the underside of the base of the rail to be lower than a cooling capacity for the central part in the width direction of the underside of the base of the rail.

Abstract: A rail heat treatment device includes a cooling header, an oscillation mechanism, and a control system including: a storage unit that stores therein at least information required for a oscillation control; and a control unit that obtains a permissible range of required cooling time for a rail that satisfies a permissible range of hardness of the rail based on a correlation expression representing a correlation between the cooling time for the rail with the cooling header and the hardness of the rail after cooling, controls a stroke and a speed of relative reciprocation of the rail and the cooling header based on the permissible range of the required cooling time, and causes the oscillation mechanism to perform the relative reciprocation of the rail and the cooling header by the stroke and at the speed.

Abstract: A rail cooling method includes: calculating, based on a relation between temperatures and an amount of warp of the rail cooled to ambient temperature after the forced cooling, the temperatures including a cooling start temperature of the head, a cooling end temperature of the head, a cooling start temperature of the foot and a cooling end temperature of the foot, a target value or a target value range for each of the temperatures so that the amount of warp of the rail at ambient temperature falls within a permissive range; and setting a cooling condition in accordance with the target value or the target value range to perform the forced cooling on the head and the foot.

Abstract: Adhesive matter remaining at the end of a cuboid metal material is reliably removed in a relatively short time while suppressing the decrease in yield rate of the metal material. Distances of the upper surface and the lower surface of a cuboid metal material from a reference position are measured using a distance measurement device in the longitudinal direction of the slab including the longitudinal end of the slab. On the basis of the measurement results, the state of remaining of adhesive matter remaining on the upper and lower surfaces of the longitudinal end of the slab is comprehended. On the basis of the state of remaining of adhesive matter, the amount and position of cutting by a cutting tool is determined. Corner removing cutting is performed on the upper and lower surfaces of the longitudinal end of the slab using the cutting tool in accordance with the determined amount and position of cutting.

Abstract: A rail restraining method for restraining a hot-rolled rail in an upright position at a time of forced cooling of a head portion and a foot portion of the rail includes defining a predetermined position within 2 meters from each of both end faces of the rail along a longitudinal direction of the rail as a first restraining position, defining a predetermined position 3 to 10 meters from the first restraining position in a direction toward center of the rail along the longitudinal direction of the rail as a second restraining position at the time of forced cooling, and restraining displacement of the rail in a vertical direction at the first restraining position and the second restraining position by a restraining force F (kN) that satisfies following Expression (1): F?100/L2??(1) where L2 (m) is a distance between the first restraining position and the second restraining position.

Abstract: A method of producing a steel product having an excellent internal quality including subjecting a steel raw material of a round section to rolling at 3 or more passes to form a steel product of round section, wherein the rolling is conducted with a pair of upper and lower flat rolls at first pass, a pair of upper and lower same or different caliber rolls at second or more passes until just before a last pass, and a pair of upper and lower round caliber rolls at the last pass, under a condition that an area reduction in the first pass is within a range of less than a total area reduction from the raw material to the product.

Abstract: A rail cooling method for forcibly cooling a rail by jetting a coolant includes jetting the coolant to a foot back part of the rail from a porous plate nozzle in which a nozzle hole at an end in a width direction is smaller than a nozzle hole at a central part in the width direction and causes a cooling capacity for the end in the width direction of the underside of the base of the rail to be lower than a cooling capacity for the central part in the width direction of the underside of the base of the rail.

Abstract: A rail heat treatment device includes a cooling header, an oscillation mechanism, and a control system including: a storage unit that stores therein at least information required for a oscillation control; and a control unit that obtains a permissible range of required cooling time for a rail that satisfies a permissible range of hardness of the rail based on a correlation expression representing a correlation between the cooling time for the rail with the cooling header and the hardness of the rail after cooling, controls a stroke and a speed of relative reciprocation of the rail and the cooling header based on the permissible range of the required cooling time, and causes the oscillation mechanism to perform the relative reciprocation of the rail and the cooling header by the stroke and at the speed.

Abstract: A rail cooling method includes: calculating, based on a relation between temperatures and an amount of warp of the rail cooled to ambient temperature after the forced cooling, the temperatures including a cooling start temperature of the head, a cooling end temperature of the head, a cooling start temperature of the foot and a cooling end temperature of the foot, a target value or a target value range for each of the temperatures so that the amount of warp of the rail at ambient temperature falls within a permissive range; and setting a cooling condition in accordance with the target value or the target value range to perform the forced cooling on the head and the foot.