Abstract: A method for manufacturing an electroplated steel sheet by continuously performing electroplating on a steel sheet, the method including disposing a slit gas nozzle having an ejection port having a width wider than a width of the steel sheet in a width direction of the steel sheet on a side of an exit of an electroplating cell for the steel sheet to pass through, and ejecting a gas through the slit gas nozzle toward the steel sheet.

Abstract: Provided are a method for measuring the magnetic transformation rate of a steel sheet in an annealing furnace and an apparatus for measuring the same, and a continuous annealing process and a continuous galvanizing process which utilize the method and the apparatus. One such method includes delivering an alternating-current driving signal to the surface of the steel sheet by using an air-core driving coil having a size larger than, a width of the steel sheet, measuring the driving signal reflected by the steel sheet by using air-core receiving coils having a size larger than the width of the steel sheet, and determining the magnetic transformation rate of the steel sheet by using a measurement processing unit based on a distance between the steel sheet and the driving coil which has been corrected by using the measured values of the driving signal obtained by using the receiving coils.

Abstract: Provided are a method for measuring the magnetic transformation rate of a steel sheet in an annealing furnace and an apparatus for measuring the same, and a continuous annealing process and a continuous galvanizing process which utilize the method and the apparatus. One such method includes delivering an alternating-current driving signal to the surface of the steel sheet by using an air-core driving coil having a size larger than, a width of the steel sheet, measuring the driving signal reflected by the steel sheet by using air-core receiving coils having a size larger than the width of the steel sheet, and determining the magnetic transformation rate of the steel sheet by using a measurement processing unit based on a distance between the steel sheet and the driving coil which has been corrected by using the measured values of the driving signal obtained by using the receiving coils.

Abstract: The invention proposes a method for heating a steel sheet wherein the generation of buckling can be prevented regardless of presence or absence of rolls restraining the steel sheet by antecedently heating the widthwise central portion of the steel sheet with a solenoid type induction heating coil having a convex form projected onto the surface of the steel sheet toward an upstream side in rapidly heating the continuously traveling steel sheet, whereby an isotherm of the steel sheet in the heating is a convex form toward the upstream side, so that a large wrinkle is generated on the steel sheet, and also proposes a heating apparatus used in this method.

Abstract: A method for manufacturing an electroplated steel sheet by continuously performing electroplating on a steel sheet, the method including disposing a slit gas nozzle having an ejection port having a width wider than a width of the steel sheet in a width direction of the steel sheet on a side of an exit of an electroplating cell for the steel sheet to pass through, and ejecting a gas through the slit gas nozzle toward the steel sheet.

Abstract: A method for manufacturing a high-strength cold-rolled steel sheet includes a temperature distribution forming step of forming a temperature distribution in a width direction of a steel sheet such that a temperature of the steel sheet increases from an end of the steel sheet in the width direction toward a center part of the steel sheet in the width direction, and a water quenching step of performing water quenching treatment on the steel sheet by immersing, in cooling water, the steel sheet on which the temperature distribution is formed in the width direction.

Abstract: A method for manufacturing a high-strength cold-rolled steel sheet includes a temperature distribution forming step of forming a temperature distribution in a width direction of a steel sheet such that a temperature of the steel sheet increases from an end of the steel sheet in the width direction toward a center part of the steel sheet in the width direction, and a water quenching step of performing water quenching treatment on the steel sheet by immersing, in cooling water, the steel sheet on which the temperature distribution is formed in the width direction.

Abstract: The invention proposes a method for heating a steel sheet wherein the generation of buckling can be prevented regardless of presence or absence of rolls restraining the steel sheet by antecedently heating the widthwise central portion of the steel sheet with a solenoid type induction heating coil having a convex form projected onto the surface of the steel sheet toward an upstream side in rapidly heating the continuously traveling steel sheet, whereby an isotherm of the steel sheet in the heating is a convex form toward the upstream side, so that a large wrinkle is generated on the steel sheet, and also proposes a heating apparatus used in this method.

Abstract: A cooling apparatus for a hot rolled steel strip including a top surface cooling means provided above a hot rolled steel strip which is transferred with transfer rollers; and a bottom surface cooling means provided below the hot rolled steel strip, each of the top surface cooling means and the bottom surface cooling means including a protective member having at least one cooling water passage hole; at least one cooling water header opposing the hot rolled steel strip separated by the protective member; and cooling water jetting nozzles protruding from the cooling water header, wherein the tips of the cooling water jetting nozzles are disposed farther from the hot rolled steel strip than the surface, opposing the hot rolled steel strip, of the protective member.

Abstract: A cooling apparatus for a hot rolled steel strip including a top surface cooling means provided above a hot rolled steel strip which is transferred with transfer rollers; and a bottom surface cooling means provided below the hot rolled steel strip, each of the top surface cooling means and the bottom surface cooling means including a protective member having at least one cooling water passage hole; at least one cooling water header opposing the hot rolled steel strip separated by the protective member; and cooling water jetting nozzles protruding from the cooling water header, wherein the tips of the cooling water jetting nozzles are disposed farther from the hot rolled steel strip than the surface, opposing the hot rolled steel strip, of the protective member.

Abstract: A method for cooling a hot rolled steel strip including transferring a hot rolled steel strip while ejecting cooling water from a cooling means at a specified ejecting condition; pinching a top end of the hot rolled steel strip by a pinching roll, at the inlet of the cooling means and/or just behind the cooling means and/or at a position on the way of the cooling means; and releasing the hot rolled steel strip sequentially from a pinch roll arranged at an upstream side, concurrently with the arrival of a top end of the steel strip to a tension adding means arranged at a downstream side.

Abstract: A cooling apparatus for a hot rolled steel strip comprising: top surface cooling means provided above a hot rolled steel strip which is transferred with transfer rollers; and a bottom surface cooling means provided below the hot rolled steel strip, each of the top surface cooling means and the bottom surface cooling means comprising: a protective member having at least one cooling water passage hole; at least one cooling water header opposing the hot rolled steel strip separated by the protective member; and cooling water jetting nozzles protruding from the cooling water header, wherein the tips of the cooling water jetting nozzles are disposed farther from the hot rolled steel strip than the surface, opposing the hot rolled steel strip, of the protective member.

Abstract: The heat-treatment apparatus for steel plate has a plurality of transfer rolls for transferring steel plate in the horizontal direction and at least one induction-heating unit for heating the steel plate. The induction-heating unit is positioned between specified adjacent transfer rolls. At least an induction-heating unit located at the most upstream side among the induction-heating units is provided with at least one pressing roll at outlet thereof to press the steel plate from above. At least the pressing roll located at the most upstream side among the pressing rolls is positioned above and facing the transfer roll located at outlet of the induction-heating unit. Owing to the heat-treatment apparatus for the steel plate, desired heat treatment can be given to the steel plate even with the induction-heating unit without adversely affecting the travel of the steel plate.

Abstract: An apparatus for cooling a hot rolled steel strip including a transfer means comprising transfer rolls to feed a steel strip which has been hot rolled by a finishing mill; a cooling means for cooling the steel strip; and accompanying rolls arranged with a clearance over the thickness of the steel strip at a position where the accompanying rolls face the transfer rolls through the steel strip to be transferred. The accompanying rolls rotate at nearly an equal peripheral speed as the transfer rolls or at a peripheral speed greater than the transfer speed of the steel strip.

Abstract: A method for cooling a hot rolled steel strip including transferring a hot rolled steel strip while ejecting cooling water from a cooling means at a specified ejecting condition; pinching a top end of the hot rolled steel strip by a pinching roll, at the inlet of the cooling means and/or just behind the cooling means and/or at a position on the way of the cooling means; and releasing the hot rolled steel strip sequentially from a pinch roll arranged at an upstream side, concurrently with the arrival of a top end of the steel strip to a tension adding means arranged at a downstream side.

Abstract: An apparatus for cooling a hot rolled steel strip including a transfer means comprising transfer rolls to feed a steel strip which has been hot rolled by a finishing mill; a cooling means for cooling the steel strip; and accompanying rolls arranged with a clearance over the thickness of the steel strip at a position where the accompanying rolls face the transfer rolls through the steel strip to be transferred. The accompanying rolls rotate at nearly an equal peripheral speed as the transfer rolls or at a peripheral speed greater than the transfer speed of the steel strip.

Abstract: An apparatus for cooling a hot rolled steel strip comprising a transfer means arranged behind a final finishing mill, the transfer means comprising a plurality of transfer rolls for transferring the steel strip; at least one upper surface cooling means arranged at an upper surface side of the transfer means for cooling the steel strip by ejecting cooling water to an upper surface of the steel strip, the upper surface cooling means being capable of moving freely up and down and having a water breaking means at least at an outlet side of the cooling apparatus and at a position corresponding to the transfer rolls; and at least one lower surface cooling means arranged at a lower surface side of the transfer means relative to the upper surface cooling means and the steel strip to be transferred, for cooling the hot strip by ejecting cooling water at a lower surface of the steel strip.

Abstract: The present invention relates to a cooling apparatus for hot rolled steel strip comprising: top surface cooling means provided above a hot rolled steel strip transferred with transfer rollers after hot rolling to cool the top surface of the hot rolled steel strip; and bottom surface cooling means provided below the hot rolled steel strip to cool the bottom surface of the hot rolled steel strip, each of the top surface cooling means and the bottom surface cooling means comprising: a protective member disposed close to the surface of the hot rolled steel strip, having at least one cooling water passage hole; at least one cooling water header opposing the hot rolled steel strip separated.

Abstract: An apparatus for cooling a hot rolled steel strip comprising a transfer means arranged behind a final finishing mill, the transfer means comprising a plurality of transfer rolls for transferring the steel strip; at least one upper surface cooling means arranged at an upper surface side of the transfer means for cooling the steel strip by ejecting cooling water to an upper surface of the steel strip, the upper surface cooling means being capable of moving freely up and down and having a water breaking means at least at an outlet side of the cooling apparatus and at a position corresponding to the transfer rolls; and at least one lower surface cooling means arranged at a lower surface side of the transfer means relative to the upper surface cooling means and the steel strip to be transferred, for cooling the hot strip by ejecting cooling water at a lower surface of the steel strip.

Abstract: A lower surface cooling box 12 is arranged between transfer rolls 11 on a runout table 3 and an upper cooling box 14 moving freely is arranged at a position corresponding to the cooling box 12 to eject cooling water to the steel strip symmetrically in the vertical direction. The steel strip passes the center of converge of cooling water from upper and lower surfaces of the steel strip. A water breaking roll 16 is provided elevating freely at least at the outlet side rotating at the same peripheral speed as the transfer rolls and is rotated to lower concurrently with passing of the steel strip top at the cooling apparatus. The upper cooling box is also lowered concurrently to cool the steel strip.