Abstract: A continuous hot-dip plating machine includes: a sink roll provided in a plating bath and configured to upwardly change a transfer direction of the steel strip; a first support roll provided in the plating bath and located above the sink roll, the first support roll being in contact with a first surface of the steel strip in contact with the sink roll; and a second support roll provided in the plating bath and located above the first support roll, the second support roll being in contact with a second surface of the steel strip opposite the first surface. A diameter of the first support roll, a diameter of the second support roll, and a vertical distance between a rotation axis of the first support roll and a rotation axis of the second support roll satisfy specific conditions.

Abstract: A steel sheet shape control method includes, (A) setting a target correction shape of the steel sheet at a position of an electromagnet to a curved shape, (B) measuring a steel sheet shape when electromagnetic correction is performed, (C) calculating the steel sheet shape in a nozzle position based on the steel sheet shape, (D) repeating (B) and (C) by resetting the target correction shape to a curved shape having a smaller amount of warp, (E) when the amount of warp of the steel sheet shape at the position of the nozzle is less than the upper limit value, (F) calculating vibration of the steel sheet at the position of the nozzle, and (G) adjusting a control gain of the electromagnet until amplitude of vibration is less than a second upper limit value when the amplitude of the vibration is equal to or more than the second upper limit value.

Abstract: A continuous hot-dip plating machine includes: a sink roll provided in a plating bath and configured to upwardly change a transfer direction of the steel strip; a first support roll provided in the plating bath and located above the sink roll, the first support roll being in contact with a first surface of the steel strip in contact with the sink roll; and a second support roll provided in the plating bath and located above the first support roll, the second support roll being in contact with a second surface of the steel strip opposite the first surface. A diameter of the first support roll, a diameter of the second support roll, and a vertical distance between a rotation axis of the first support roll and a rotation axis of the second support roll satisfy specific conditions.

Abstract: An on-line coating adhesion determination apparatus of a galvannealed steel sheet, includes: an X-ray tube which irradiates a galvannealed steel sheet that travels on a transportation line, with X-rays; an optical system which allows the X-rays emitted from the X-ray tube to irradiate the galvannealed steel sheet as a parallel beam and be diffracted; and a detector which measures the intensity of the diffracted X-rays and is installed at a position at which the X-ray diffraction peak corresponding to a crystal lattice spacing d of 1.5 ? or higher is detected, in which an emitted beam luminance of the X-rays is 20 W/mm2 or higher, and the width-direction gain of the X-rays in the optical system is 0.15 or higher. The crystal lattice spacing d may be 1.914 ?. In addition, the energy of the incident X-rays from the X-ray tube may be lower than the excitation energy of Fe-K? fluorescence X-ray.

Abstract: A method of supplying a Zn—Al alloy to a molten zinc pot which accommodates a molten zinc bath in a hot dip galvanizing line, includes: supplying the Zn—Al alloy from a supply portion provided at a lower portion of an insertion guide having a pipe shape, in which the supply portion is immersed between an inner wall of the molten zinc pot on a downstream side in a travelling direction of a steel sheet and a front support roll installed in the molten zinc bath at a depth within ±400 mm from a lower end of the front support roll, and an inside of the insertion guide is pressurized by inert gas to prevent the molten zinc bath from advancing to the inside of the insertion guide.

Abstract: A steel sheet shape control method includes, (A) setting a target correction shape of the steel sheet at a position of an electromagnet to a curved shape, (B) measuring a steel sheet shape when electromagnetic correction is performed, (C) calculating the steel sheet shape in a nozzle position based on the steel sheet shape, (D) repeating (B) and (C) by resetting the target correction shape to a curved shape having a smaller amount of warp, (E) when the amount of warp of the steel sheet shape at the position of the nozzle is less than the upper limit value, (F) calculating vibration of the steel sheet at the position of the nozzle, and (G) adjusting a control gain of the electromagnet until amplitude of vibration is less than a second upper limit value when the amplitude of the vibration is equal to or more than the second upper limit value.

Abstract: A steel sheet shape control method includes, (A) setting a target correction shape of the steel sheet at a position of an electromagnet to a curved shape, (B) measuring a steel sheet shape when electromagnetic correction is performed, (C) calculating the steel sheet shape in a nozzle position based on the steel sheet shape, (D) repeating (B) and (C) by resetting the target correction shape to a curved shape having a smaller amount of warp, (E) when the amount of warp of the steel sheet shape at the position of the nozzle is less than the upper limit value, (F) calculating vibration of the steel sheet at the position of the nozzle, and (G) adjusting a control gain of the electromagnet until amplitude of vibration is less than a second upper limit value when the amplitude of the vibration is equal to or more than the second upper limit value.

Abstract: A method of supplying a Zn—Al alloy to a molten zinc pot which accommodates a molten zinc bath in a hot dip galvanizing line, includes: supplying the Zn—Al alloy from a supply portion provided at a lower portion of an insertion guide having a pipe shape, in which the supply portion is immersed between an inner wall of the molten zinc pot on a downstream side in a travelling direction of a steel sheet and a front support roll installed in the molten zinc bath at a depth within ±400 mm from a lower end of the front support roll, and an inside of the insertion guide is pressurized by inert gas to prevent the molten zinc bath from advancing to the inside of the insertion guide.

Abstract: A method of supplying a Zn—Al alloy to a molten zinc pot which accommodates a molten zinc bath in a hot dip galvanizing line, includes: supplying the Zn—Al alloy from a supply portion provided at a lower portion of an insertion guide having a pipe shape, in which the supply portion is immersed between an inner wall of the molten zinc pot on a downstream side in a travelling direction of a steel sheet and a front support roll installed in the molten zinc bath at a depth within ±400 mm from a lower end of the front support roll, and an inside of the insertion guide is pressurized by inert gas to prevent the molten zinc bath from advancing to the inside of the insertion guide.

Abstract: An on-line coating adhesion determination apparatus of a galvannealed steel sheet, includes: an X-ray tube which irradiates a galvannealed steel sheet that travels on a transportation line, with X-rays; an optical system which allows the X-rays emitted from the X-ray tube to irradiate the galvannealed steel sheet as a parallel beam and be diffracted; and a detector which measures the intensity of the diffracted X-rays and is installed at a position at which the X-ray diffraction peak corresponding to a crystal lattice spacing d of 1.5 ? or higher is detected, in which an emitted beam luminance of the X-rays is 20 W/mm2 or higher, and the width-direction gain of the X-rays in the optical system is 0.15 or higher. The crystal lattice spacing d may be 1.914 ?. In addition, the energy of the incident X-rays from the X-ray tube may be lower than the excitation energy of Fe-K? fluorescence X-ray.

Abstract: A flow regulating member of a hot dip coating tank which is able to suppress stir-up of bottom dross, characterized by being provided with flow regulating member horizontal plates which are respectively arranged horizontally from below two side end parts of a sink roll, which is arranged inside of a coating tank in a rotatable manner, toward outside directions of the sink roll and side members which are arranged at positions separated from the two ends of the sink roll, which extend upward from the end parts of the respective horizontal plates, and in which large numbers of dispersion holes are formed, the side members having an aperture ratio of 20 to 80%, and the dispersion holes having a hole diameter of 5 to 50 mm.

Abstract: A flow regulating member of a hot dip coating tank which can suppress stir-up of bottom dross, characterized by being provided with horizontal plates which are respectively arranged horizontally from below two side end parts of a sink roll, which is arranged inside of a coating tank in a rotatable manner, toward outside directions of the sink roll and louvers which are arranged above from the end parts of the respective horizontal plates at positions separated from the two ends of the sink roll and which have flow direction changing members which are slanted so that their heights become gradually higher toward the wall surface sides of the coating tank.

Abstract: A steel sheet shape control method includes, (A) setting a target correction shape of the steel sheet at a position of an electromagnet to a curved shape, (B) measuring a steel sheet shape when electromagnetic correction is performed, (C) calculating the steel sheet shape in a nozzle position based on the steel sheet shape, (D) repeating (B) and (C) by resetting the target correction shape to a curved shape having a smaller amount of warp, (E) when the amount of warp of the steel sheet shape at the position of the nozzle is less than the upper limit value, (F) calculating vibration of the steel sheet at the position of the nozzle, and (G) adjusting a control gain of the electromagnet until amplitude of vibration is less than a second upper limit value when the amplitude of the vibration is equal to or more than the second upper limit value.

Abstract: A method of supplying a Zn—Al alloy to a molten zinc pot which accommodates a molten zinc bath in a hot dip galvanizing line, includes: supplying the Zn—Al alloy from a supply portion provided at a lower portion of an insertion guide having a pipe shape, in which the supply portion is immersed between an inner wall of the molten zinc pot on a downstream side in a travelling direction of a steel sheet and a front support roll installed in the molten zinc bath at a depth within ±400 mm from a lower end of the front support roll, and an inside of the insertion guide is pressurized by inert gas to prevent the molten zinc bath from advancing to the inside of the insertion guide.

Abstract: A flow regulating member of a hot dip coating tank which is able to suppress stir-up of bottom dross, characterized by being provided with flow regulating member horizontal plates which are respectively arranged horizontally from below two side end parts of a sink roll, which is arranged inside of a coating tank in a rotatable manner, toward outside directions of the sink roll and side members which are arranged at positions separated from the two ends of the sink roll, which extend upward from the end parts of the respective horizontal plates, and in which large numbers of dispersion holes are formed, the side members having an aperture ratio of 20 to 80%, and the dispersion holes having a hole diameter of 5 to 50 mm.

Abstract: A flow regulating member of a hot dip coating tank which can suppress stir-up of bottom dross, characterized by being provided with horizontal plates which are respectively arranged horizontally from below two side end parts of a sink roll, which is arranged inside of a coating tank in a rotatable manner, toward outside directions of the sink roll and louvers which are arranged above from the end parts of the respective horizontal plates at positions separated from the two ends of the sink roll and which have flow direction changing members which are slanted so that their heights become gradually higher toward the wall surface sides of the coating tank.