Development of Criteria Specifying the Conditions of Interaction between the Scale with the Rolls of Continuous Cast Machine and Continuous Cast Billets

摘要

The study of surface condition of the rolls of continuous casting machine (CC-machine) of the secondary cooling zone is undertaken. It was stated that their working surfaces include the segments with stuck and peeled-off scale. The surface profilograms of the rolls with pickup scale are obtained. The domelike, tapered and trapezoidal form of fragments of the scale with a height 3-4 mm and tilt angles between the side faces of 43-88 are the most typical forms. Based on the elements of the plasticity theory, the problem of determination of stress-strain behavior of continuous casting steel billets is solved in the process of indentation of the scale fragments into it. The mathematical relation between geometrical parameters of scale fragments and the thickness of crystallized jacket is found that allows determining a stress strain state criteria in accordance with that the scale pickup on the roll surface is carried out or its indentation into internal layers of CC steel billets with its following holding. It was stated that the indentation of good-size scale fragments in relatively thin crystallized skin creates comfortable facilities for pick-up of scale on the rolls, and the indentation of small-sized scale fragments in the thick crystallized jacket especially with large tilt angles between the side surfaces of fragments makes possible for their hold-up at the surface of concast steel billets in the imbedded condition. It was determined the criteria which contains two necessary conditions whereby the scale sticking on the rolls of CC machine is carried out or the indentation in continuous-casting machine followed by holding in it.