| 摘要 |
PROBLEM TO BE SOLVED: To improve the quality of a plated layer, and to provide a uniform plating thickness by suppressing the vibration and the contact of a steel strip in controlling the plating thickness making use of an alternating magnetic field generating coil. SOLUTION: A steel strip 10 is held by a pair of rolls 30A, 30B, and a pair of support rolls 95A, 95B. A molten metal bath 40 is formed between the rolls and the steel strip 10 above the rolls 30A, 30B, and the hot dip metal coating is continuously implemented on a surface of the upwardly moving steel strip 10. A plating thickness controlling means is an alternating magnetic field generating coil installed above the molten metal bath between the rolls 30A, 30B and the support rolls 95A, 95B, and frequency of the current charged in the alternating magnetic field generating coil is set to be higher than the specified multiple of the natural frequency of the steel strip, and the plating thickness is controlled by suppressing the contact or the vibration of the steel strip by the alternating magnetic field generating coil, and the molten metal bath and the alternating magnetic field generating coil are installed in a case filled with a non-oxidizing gas.
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