Variation of Oil Introduction Behaviour during Oil-in-Water Emulsion Rolling

In the cold rolling of steel plates and the hot rolling of aluminium plates, an oil-in-water emulsion is used as the rolling oil, both as a coolant and a fire retardant. Understanding the formation mechanisms of the oil film that formed in a roll bite is important for controlling the lubricity and surface quality of the product. This film is formed by introducing oil that spreads on the rolls and strip, which is called "plate-out", and by introducing oil droplets into the inlet zone. However, the effects of these two oil introduction methods on the oil film that formed in the roll bite and the relationship between them have not yet been clarified. In our previous study, oil-film thickness was estimated from the volume of the tracer left on the strip after rolling and the proportion of the volume to that of the oil introduced. The mutual relationships between the volume of the introduced oil and the emulsion particle size, the oil concentration of the emulsion, and rolling velocity were determined. In this study, the effect of plate-out volume on the oil film that formed between the rolls and the strip was investigated by comparing oil-film thickness and plate-out volume. In addition, the behaviour of the introduction of oil droplets for various plate-out volumes was investigated by controlling the supply conditions of the oil-in-water emulsion and the velocity of rolling on a test mill. The effect of plate-out volume was found to decrease and that of oil-droplet introduction was found to increase with an increase in rolling velocity.