Research On The Nonlinear Dynamic Characteristics Of Roll Crossing In The Micro-Scale Of Roll System

The demand for high-quality strip products has increased sharply,making high-precision strip rolling mills constantly in the process of overload production and upgrading.This has also led to more obvious vibration problems in production equipment.The industry urgently needs to solve the vibration problems of rolling mills from the root cause.The rolling mill is a collection of complex multi-structure systems,including roll system,main frame,hydraulic system and transmission system.During production,the rolling mill is in a high-speed and heavy-load nonlinear multi-dimensional motion coupling state,which makes the research of rolling mill vibration extremely complicated and difficult.In this paper,the upstream stand of the finishing mill of a hot rolling mill is taken as the research object.Based on the field vibration test,the vibrating slab and the stable slab are compared in production,combined with the vibration characteristics of the rolling mill and the reason for the vibration is found.The structural parameters and process parameters of a variety of vibrating slabs were analyzed,the deep common theoretical technical problems contained in the rolling mill were excavated and the cross-offset phenomenon of the work rolls in the rolling process was discovered.The displacement of the rolling mill is a micro-scale displacement relative to the size of the rolling mill.In this paper,the structure of the rolling mill is simplified to a "mass-stiffness-damping" model.According to the principles of rolling mechanics and dynamics,the working rolls of the rolling mill are considered.The offset distance and structural gap of the backing rolls and the formula description of the work roll cross phenomenon,combined with the rolling force calculation model established based on the sims formula and the dynamic geometric characteristics of the deformation zone and the vertical-horizontal dynamics model of the roll system is established.Through mathematical derivation,it is found that the contact stiffness of the roll is a variable stiffness that changes with the cross state.The rolling mill dynamics equations have horizontal and vertical coupling,that is,the rolling mill dynamics model is a nonlinear vertical-horizontal coupling under the cross state of work rolls model.Based on the established nonlinear vertical-horizontal coupling model under the cross state of the rolls,this paper simulates the vibration state of the rolling mill under different parameters,analyzes the dynamic vibration characteristics under the influence of different parameters,and explains the parameters such as the cross offset state and the offset parameters.The impact of the change on the stability of the rolling mill.For the tested rolling mill,find suitable strategies for improving the process parameters such as offset,roll diameter,incoming material thickness,rolling speed,tensile stress,etc,so that the vibration phenomenon of the rolling mill during operation is reduced and the stability is enhanced.