| 摘要 |
PURPOSE:To make operation simple and enable optimum film to be formed by changing the oxygen concentration in oxidative gas of a fixed flow rate in correspondence to the change of the travelling speed of the steel hoop thereby oxidizing one side of the steel hoop. CONSTITUTION:The oxidizing gas having been controlled to a correct concentration is blown from a nozzle 5 to a steel hoop 1 which has been activated of its surfaces by being heated in a reducing atmosphere and has been cooled to the temperature suited to plating, in a turn-down roll 3 part. Thereby, an oxide film is formed on the surfaces of the steel hoop 1. the excess gas is exhausted to the outside through suction and exhaust ports 6, 6'. In order to prevent the leakage of the oxidizing gas to the reducing atmosphere 2 or snout part 8, inert gas is blown out from the nozzles 7, 7' to seal. In this case, change of the oxidizing conditions and the flow rate of the oxidizing gas are made constant in correspondence to the change in the travelling speed of the steel hoop 1 and the O2 concentration is controlled in performing the oxidation. As a result, the oxidation is performed at the constant seal gas flow rate and suction and exhaust conditions and therefore there are no in-furnace pollutions of the oxidizing gas at all and always good one-side plated steel plates are obtainable. |
