四辊轧机辊系偏移距机理的不确定性和微尺度静定性

Indeterminacy of the Offset Mechanism and Microscale Static Determinacy of Roll System in Four-high Mill

生产板带的四辊轧机辊系,普遍设置偏移距求得轧辊间平行定位及其稳定以防止辊间交叉,成为四辊轧机辊系平行定位机理编入轧机教科书及参考书中。近代相继出现的现代四辊轧机辊系都设置偏移距,但未能保证其机理的确定性,辊间动态交叉现象的发生屡禁不止,引发超大轴向力损坏推力滚动轴承或生成轧制支反力偏差破坏板形控制的稳定性。设置偏移距3mm的高速铝箔四辊轧机轴向力在线检测试验,揭示轧制过程中工作辊与支承辊之间发生规律性动态交叉现象。轧制中轧辊之间的动态交叉行为,与轴承座和机架窗口立柱间微小间隙大小相对应,只限于轧机的交叉角β≤0.05°区间,远小于交叉(Paircross,PC)轧机的交叉角(β=1°～1.5°),但派生的轴向力超出额定值的3倍以上。四辊轧机模拟辊系偏移距静态零调试验,探明轧辊间初始安装位置不变没有轧辊的水平位移。辊间动态交叉现象和静态水平位移为零的两种结果,揭示出设置偏移距机理的不确定性,不能用于四辊轧机辊系平行定位及稳定性设计。

In the four-high mill used for rolling plate,an offset is generally set to keep the rolls parallel and prevent the cross between the rolls,and which becomes the parallel positioning mechanism of roll system in four-high mill entered into the textbook of rolling mills.In all contemporary four-high mills,there is an offset between the rolls.But the offset cannot ensure the certainty of its mechanism,and the dynamic cross between the rolls happens frequently,which induces ultra-large axial force to damage the thrust rolling bearing or generate support reaction deviation in rolling to break the stability of plate shape control.Online inspection test of the axial force of a high-speed four-high mill for rolling aluminum foil and with a 3 mm offset distance is carried out,which reveals the occurrence of regular dynamic cross between work roll and backup roll during the rolling process.The dynamic cross behavior between the rolls is corresponding to the size of small clearance between bearing seat and housing window column,limited only in the range of β≤0.05° cross angle of rolling mill,and far lower than β=1°～1.5° cross angle of PC mill.But the derivative axial force of the dynamic cross exceeds three times of the rated value The static acyclic test of the offset distance of four-high mill roll system proves that with constant original installation position between the rolls there is no horizontal displacement of rolls.The dynamic cross phenomenon and zero static horizontal displacement reveal the indeterminacy of the mechanism of setting offset distance,so it cannot be used for parallel positioning and stability design of four-high mill.