Alkaline cleaning and degreasing is an important treatment procedure before reduction and annealing in continuous hot dip plating of American steel strip.Its function is to basically remove the steel belt, the surface oil and iron powder and other impurities through the steps of alkaline spraying or soaking, alkaline cleaning, electrolytic alkaline washing, water brushing and water spraying.
When the strip is rolled on a cold mill, the surface of the strip will inevitably be covered with oil and iron powder.Oil pollution is mainly rolling oil in emulsifying liquid;The iron powder is rubbed off the surface of the steel belt and roll under the action of friction caused by the great rolling pressure (especially in the front and back sliding areas of the deformation of the steel belt, where the friction coefficient is much higher than the rolling friction).Because the material of steel belt and roll is different, their wear resistance is different greatly. The iron powder is mostly rubbed off from the surface of steel belt, while the iron powder rubbed off from the surface of roll only accounts for a small part.The oil, iron powder on the board is the object to be removed in the degreasing section.
So, how does degreasing work?
1. The classification and properties of rolling oil in order to understand the degreasing principle, the classification and properties of rolling oil should be clarified first.
Rolling oil can be divided into three types.
One is saponifiable oil.Animal and vegetable oils, such as pork, beef and palm oil, are saponifiable.The property of saponifiable oil is that it can be saponified and emulsified.
Second, non-royal oil.All mineral oils are non-saponifiable.The nature of non-saponifiable oil is that it can not occur saponification, can only occur, emulsification.
Third, some synthetic lipids.Its property lies between saponifiable oil and non-saponifiable oil, which is mainly removed by emulsification and has certain saponification.