In the high-speed cold tandem rolling process of thin plate,chatter or slip instability gives rise to the deterioration of equipment and product quality.Macroscopic instability behavior is closely related to interfaci...In the high-speed cold tandem rolling process of thin plate,chatter or slip instability gives rise to the deterioration of equipment and product quality.Macroscopic instability behavior is closely related to interfacial friction-lubrication con-dition which is generally characterized by the friction coefficient.However,with higher and higher speed requirements,the commonly used model of friction coefficient is no longer applicable and accurate.A novel approach is suggested to calculate the speed-dependent friction coefficient,in which the viscosity-pressure-temperature effects of the lubricant,surface roughness states of work rolls and rolled piece are comprehensively involved and the mixed flm lubrication theory is applied.Subsequently,the influences of friction coefficient on the instability of slip and chatter are investigated for a five-stand cold tandem rolling mill.On one side,the critical friction coefficient for each stand is determined by calculating the corresponding slip factor;on the other hand,the friction coefficient varying with rolling speed is combined with the model of theoretical critical rolling speed presented under constant friction coefficient,so that the speed threshold is determined.Furthermore,the stable and unstable regions corresponding to the rear three stands are individually discussed,and the technical strategies are proposed to suppress both slip and chatter frequently occurring in the actual rolling process.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51775038).
文摘In the high-speed cold tandem rolling process of thin plate,chatter or slip instability gives rise to the deterioration of equipment and product quality.Macroscopic instability behavior is closely related to interfacial friction-lubrication con-dition which is generally characterized by the friction coefficient.However,with higher and higher speed requirements,the commonly used model of friction coefficient is no longer applicable and accurate.A novel approach is suggested to calculate the speed-dependent friction coefficient,in which the viscosity-pressure-temperature effects of the lubricant,surface roughness states of work rolls and rolled piece are comprehensively involved and the mixed flm lubrication theory is applied.Subsequently,the influences of friction coefficient on the instability of slip and chatter are investigated for a five-stand cold tandem rolling mill.On one side,the critical friction coefficient for each stand is determined by calculating the corresponding slip factor;on the other hand,the friction coefficient varying with rolling speed is combined with the model of theoretical critical rolling speed presented under constant friction coefficient,so that the speed threshold is determined.Furthermore,the stable and unstable regions corresponding to the rear three stands are individually discussed,and the technical strategies are proposed to suppress both slip and chatter frequently occurring in the actual rolling process.
