Research On Dynamic Modeling And Dynamic Characteristics Of Hot Strip Rolling Mill

The upgrading of the strip product inevitably increases the running load of the rolling mill equipment,and the vibration problem is becoming more and more prominent in the rolling process.So,the research on the dynamic characteristics of rolling mill system is imminent.Rolling process is a high-speed,high-load,high-precision and complex nonlinear dynamic production process.And the dynamic characteristic is composed of press system,roll system,main driving system and steel deformation system,which are determined by the interaction of multiple subsystems of different physical attributes.This paper makes a hot four-high mill system as the research object,the dynamic characteristics of rolling mill are studied from three aspects: the driving system,the damping characteristic of rolling interface friction and the characteristic of roll swing basing on the phenomena of rolling mill vibration test.The second finishing rolling mill(F2)was tested synthetically,and the oppressive experiment,climbing experiment and vibration experiment were carried out.The main vibration phenomena were analyzed in detail,and the dynamic characteristics of the hot rolling mill were mastered,such as the main vibration forms(forced vibration and self-excited vibration)and the vibration mechanism.In addition,the common technologies of stable rolling process were excavated,which guided the main research contents of this subject.The steady mechanical model of the arc tooth gear meshing was established considering the structural parameters of the arc tooth meshing in the driving system.The mechanism and distribution law of the meshing force and the additional torque were studied.And then the dynamic meshing force and the additional torque were studied by considering the dynamic displacement and dynamic load torque.The driving system dynamic model considering with the dynamic characteristics of arc tooth gear was established for the first time.Then the inherent characteristics and vibration mechanism of the driving system were analyzed.The influences of the working parameters and the rolling process on the stability of the driving system were discussed.The results showed that the larger the axial tilt Angle is,the bigger the rolling speed is,the higher the wear degree is,the lower the stability is.The application of the arc tooth gear shaft provides convenience to the rolling mill system,and there is also a potential hazard.It need maintain and test timely,to avoid causing severe vibration.The dynamic flow velocity model of steel was established according to the dynamic geometric relationship in the deformation zone.Considering the distribution of the mix friction state(sliding zone,braking zone and stagnation zone)in the rolling interface,the dynamic friction force model of the interface was established.Based on this model,the dynamic variation law of friction force in the interface was analyzed.The mechanism of torsional friction negative damping and horizontal friction negative damping in the rolling interface were studied respectively,as well as the influence of rolling parameters on the rolling interface stability.Then,the torsional-horizontal coupling vibration model of rolling mill was established based on the dynamic friction force model,and the self-excited vibration mechanism was discussed according to the rolling process parameters,the rolling mill structure and the field test data.The results showed that the larger the reduction amount is,the larger the deformation resistance is,the larger the roll radius is,the smaller the friction coefficient,the larger the friction negative damping is,and the stability is lower.It could provide theoretical guidance for making reasonable rolling process.Considering the transverse load distribution,the asymmetry on both sides of the rolling mill structure,the structural clearance,the coupling relationship between vertical motion and horizontal motion and the external disturbance force,the dynamic model of the swing vibration(translational and rotational)was established in the hot rolling process.The inherent characteristics of the roll system were solved,and the vibration mechanism and distribution of chatter marks were revealed.At last,the effects of arc tooth gear wear degree,rolling speed and structural clearance on the stability of roll system were discussed,which could guide the vibration control and suppression.The dynamic relationship of the three sub-systems namely the driving system dynamic model considering with the dynamic characteristics of arc tooth gear,the dynamic friction force model on the interface considering the distribution of the mix friction state,and the dynamics model of roll system were studied.And the whole coupling dynamic model of hot rolling mill was established.The dynamic behavior of the rolling mill system was simulated and analyzed.The coupling relationship between the rolling mill system,the transfer path of vibration energy and the vibration mechanism were revealed.The establishment of the dynamic model of hot rolling mill is helpful to reveal the mechanism of different vibration forms,and it can improve the stability of rolling process by optimizing the rolling process parameters and rolling mill structure.In addition,the improvement of the model system can provide theoretical guidance for the effective and accurate prediction of the rolling equipment health status,and promote the intelligent management of the rolling equipment.