DEVELOPMENT OF STATICALLY DETERMINATE PLATE ROLLING MILLS BASED ON MICRO-SCALE PARAMETERS

摘要

Contemporary plate rolling mills and pinch pass mills, which are unstable during the rolling process, are all statically indeterminate structures influenced by micro-scale parameters. The micro-scale parameters include bending deformations of the rolls and the side clearances between the chocks and the side surfaces of the housing window. All these are less than 1 mm, and they have an important effect on the skeletal structure of the roll systems of the mill. If the influence of micro-scale parameters is not considered in the design of the rolling mill, the skeletal structure of the roll system is incomplete and lacks kinematic links and pairs. The statically indeterminate nature of traditional rolling mills results in numerous disadvantages, including the frequent burning loss of the end-thrust bearing caused by excessive axial forces, the lateral movement of the strip owing to the deviation of the rolling load acting on the both ends of backup roll, the short service life of the four-row radial roller bearings on the back-up roll, and the quality of product tends to deteriorate due to the unstable operation of the control system, to mention a few. Because of the flattening effect between the rolls, the setting of the offset distance does not achieve the desired purpose and leads to the deviation of rolling load due to the asymmetric cross between the roll axes. To alleviate the above shortcomings, a new type of rolling mill with a statically determinate structure in which the horizontal offset distance between the roll axes is set to zero is thus proposed. In order to keep the rolls parallel and prevent cross between the rolls, a thrust device is designed, which also ensures sufficient free space to allow convenient roll replacement and allow for the thermal expansion of the chocks. In addition, back-up roll systems with component force bases as well as intermediate roll systems are designed in accordance with the theory of statically determinate characteristics with micro-scale parameters.