Non-symmetrical Cross-rolling Study

A combined theoretical and experimental study is carried out for the process of non-symmetric cross rolling. The experimental data indicate that the non-symmetric cross rolling process not only produces reliable control on both shape of strip and lateral thickness deviation, but also reduces significantly the power thickness deviation, but also reduces significantly the power consumption and rolling pressure, and the latter could extend the service life of rolls. The laws governing the variation of sheet thickness fluctuation, as well as the optimum cross rolling angle controlling the shape of strip are revealed through our experiments. Those laws include that the forward slip coefficient for cross rolling is always larger than that for conventional rolling, and the widening generated by cross rolling is always less than that by conventional rolling. A set of continuously regulating apparatus is designed to achieve continuous regulation of the cross rolling angle, as well, as to eliminate the endwise slip of the rolls, A new method on solving the rolling contact problems is proposed in the present" thesis. The essence of this methodology lies in converting the contact surface into surface of known velocity distribution of the rolling movement, and good agreement is obtained between the computation based on this method and the experiments. A two-dimensional pressure formula is established in the present thesis by means of the slab method. This formula is shown of good accuracy and thus applicable to engineering designs. It is also proved theoretically that the stress distribution generated bycross rolling is more homogeneous than that produced by previous rolling step, so that the shape of strip can be efficiently improved. A formula determining the optimum cross rolling angle is derived and its prediction is in good agreement wi th the experimerit data. It then can be used for the control and design of cross rolling.