考虑轧机液压压下缸和平衡缸对辊系的约束影响，建立了轧机辊系的分段非线性动力学模型。分别采用奇点稳定性理论和奇异性理论分析了该分段非线性系统在自治情况和非自治情况下的分岔特性，得到不同系统参数下的分岔形态。最后根据某轧机结构参数，模拟了轧机分段非线性辊系系统在不同的外部扰动下的局部分岔行为，发现随着外扰参数的变化该系统是周期运动、倍周期运动以及混沌等多种运动形态相互交替的复杂动力学系统，外部扰动参数的变化影响系统的运动形态，这为研究和抑制轧机辊系振动问题提供了理论参考。

A piecewise nonlinear dynamic model of rolling mill is established which contains the sanction of hyardulic system. The characteristics of bifurcation of autonomy system and nonautonomy system are analyzed by means of sigular stability theory and singularity theory, respectivly, and different topological structure of solution are obtained under different parameters. At last, the numerical simulation of rolling mill exhibits many different motions such as periodic motion, period-doubling motion and chaos, etc. It found that the change of parameter influences the motion state of the system. The results supply theoretical bases for optimal control of rolling mill.