Theoretical Study On Vibration Prediction Of Hot Rolled High Strength Steel Sheet Mill

High strength steel sheet is widely used in industry field such as automobile industry,household electrical appliances and precision instrument.The rolling mill has obvious vibration,when the rolling speed reaches a high degree in the process of hot rolling production of high strength steel sheet.That affects product quality and production efficiency of high strength steel sheet and even causes the damage of parts and components of rolling mill equipment.The vibration problem of mill for high strength steel sheet is more complicated and the adverse effects in the operation of the equipment are more obvious with the development of rolling mill equipment towards large-scale,automation and intellectualization.Therefore,the mechanism analysis of rolling mill vibration in high-strength steel sheet production process and realizing the prediction of vibration for rolling mill are necessary,which is of great significance to realize the stable production of high strength steel sheet and the fault diagnosis for full process production and manufacturing.In this paper,the hot rolled of high strength steel sheet was taken as the research object.On the one hand,this paper calculated the rolling force of the hot-rolled sheet with mixed friction state,established the vertical vibration model of hot strip mill,and further established the self-excited vibration model,thus completed the mechanism analysis of rolling mill vibration.On the other hand,with the help of the acquisition of rolling process parameters,this paper realized the prediction of rolling mill vibration and the establishment of a complete monitoring and prediction system.The main research contents are as follows:Firstly,the model of rolling force of rolling deformation zone of the hot rolled sheet was set up with considering the physical characteristics of the sheet and the result of the roll force was calculated;In addition,a simplified six-degree-of-freedom vertical vibration model of hot strip mill is established by lumped mass method.The natural frequencies and main modes of vertical vibration of hot strip mill are solved,and the characteristics of vertical vibration of hot strip mill are analyze.Furthermore,the model of the vibration of the rolling mill is established,and then the simulation of the vibration is carried out which combined with the calculated rolling force and the vertical vibration characteristics of the rolling mill.In the end,the vibration curves of the roll part under the action of the exciting force are obtained.Secondly,according to the production process parameters and the collected vibration signals,the DBN algorithm is used to reduce the dimension of the data,and the BP structure parameters are optimized by genetic algorithm to realize the vibration prediction of high-strength steel sheet mill.And the influence of production process parameters on rolling mill vibration prediction is analyzed.Finally,the vibration monitoring and forecasting system of the high-strength steel sheet mill is built.The mill vibration signals and production process parameters are collected.The rolling mill vibration prediction and simulation are completed so that they could be integrated into the steel production fault diagnosis system.