Plate-out Behaviors of O/W Emulsions for Cold Rolling in a Short Time Interval

Abstract

Synopsis : O/W emulsions are widely used in tandem cold rolling mills as coolants, in order to reduce friction forces and prevent heat scratches. The lubricating properties may be determined by various factors, and the amount of plated out oil on strip surface is one of the important ones, as well as dynamic concentration mechanics of emulsions at inlet of roll bite, on which much interest has been paid since 1970s. However, plate-out oil film formation has been recognized as a quite important factor in production mill operation, and the understandings of more details are necessary for higher speed and more efficient cold rolling mills. Therefore, the paper is concerned with the plate-out properties, especially the oil film formation in a quite short time. Because the plate-out oil formation is caused through phase transformation of O/W emulsion to oil film, the process may be time dependent, even if the time is quite limited in production high-speed rolling mills. In this paper, firstly a new method to evaluate the amount of plate-out oil is proposed, which makes it possible that the evaluation in quite a short time less than 0.1 s. Then, the time dependency of the oil film formation is clarified, and the amount of plated-out oil increases with time from emulsion supply to strip surface. Also, the influence of oil concentration, oil droplet size of O/W emulsions and other factors are examined by the method, which are compared with the results by conventional test methods.

Hydrodynamics and heat transfer characteristics of oil-in-water emulsion droplets impinging on hot stainless steel foil

“…The lubricating properties of emulsion liquids have been extensively studied by researchers and engineers in the field of tribology [1][2][3]. Emulsions composed of water and oil are employed as the metalworking fluid in various operations such as rolling, cutting, ironing, and grinding [1][2][3][4][5]. In steel-making industries, spray jet impingement of O/W emulsions is widely used in cold rolling mills for lubrication and cooling.…”

“…formed on the material surfaces [4] and reducing unwanted local thermal expansion/contraction of work rolls. The heat transfer characteristics of emulsion spray jets impinging on a hot solid play an important role in determining engineering demands [5].…”

Influence of Plate-out Oil Film on Lubrication Characteristics in Cold Rolling

“…In order to evaluate the plate-out oil film formed in a very short time, Kimura et al 10) developed the test machine shown schematically in Fig. 2.…”

“…This theory was reported by Roberts et al 4) in the 1970s. Recently, an estimation model for oil film thickness has been proposed using a new starvation model considering the plate-out film on the roll and strip surfaces, as proposed by Inagaki et al 9) Also, Kimura et al 10) reported plate-out oil film formation on the strip surface during a very short time.…”

Plate-out efficiency related to oil-in-water emulsions supply conditions on cold rolling strip

“…Moreover, from the measured results of the plate-out oil film shown in Figure 13, high plate-out efficiency is also maintained. Kimura et al 11 reported the influence of the oil droplet size on plate-out oil film. Therefore, from the point of widely control of plate-out oil film, it is important that oil droplet distribution can be controlled by air atomizing.…”