2013 年 99 巻 10 号 p. 610-616
Hot-dip galvanized steel sheets are often used for automobile exterior body panels to enhance the corrosion performance. The requirements for their surface appearance from automakers have become higher recently. Especially, a uniform coating layer of zinc is required. In a continuous hot-dip galvanizing line (CGL), a pair of gas wipers, which are installed just above the zinc pot, is used to control the thickness of the coating layer. The strip vibration at the gas wipers causes the uneven coating thickness in the traveling direction, while the cross-bow of the strip leads to the unevenness in the width direction. The behavior of the strip at the gas wipers should be stable for the uniform coating layer. In order to make the strip stable and flat, a strip vibration and shape control technique using electromagnets has been developed. It greatly contributes to produce hot-dip galvanized steel sheets with excellent surface appearance.
