Research on the Vertical Vibration Characteristics of Hydraulic Screw Down System of Rolling Mill under Nonlinear Friction

Yongshun Zhang,Yong Zhu,Zhenbao Li,Wanlu Jiang

doi:10.3390/pr7110792

Abstract

The rolling mill with hydraulic system is widely used in the production of strip steel. For the problem of vertical vibration of the rolling mill, the effects of different equivalent damping coefficient, leakage coefficient, and proportional coefficient of the controller on the hydraulic screw down system of the rolling mill are studied, respectively. First, a vertical vibration model of a hydraulic screw down system was established, considering the nonlinear friction and parameter uncertainty of the press cylinder. Second, the correlation between different equivalent damping coefficient, internal leakage coefficient, proportional coefficient, vertical vibration was analyzed. The simulation results show that, in the closed-loop state, when Proportional-Integral-Derivative (PID) controller parameters are fixed, due to the change of the equivalent damping coefficient and internal leakage coefficient, the system will have parameter uncertainty, which may lead to the failure of the PID controller and the vertical vibration of the system. This study has theoretical and practical significance for analyzing the mechanism of vertical vibration of the rolling mill.

Highlights

With the continuous improvement of strip material properties, high requirements for rolling equipment appears
The purpose of this work is to clarify the influence of process parameters on the vertical vibration of the rolling mill, with nonlinear friction force taken into process parameters on the vertical vibration of the rolling mill, with nonlinear friction force taken account, and to evaluate the influence of vertical vibration by introducing the vibration severity [26,27], into account, and to evaluate the influence of vertical vibration by introducing the vibration severity which makes the vibration monitoring of the rolling mill in industrial fields more intuitive and can
It is found that different equivalent damping coefficients have a great influence on the nonlinear system

Summary

Introduction

With the continuous improvement of strip material properties, high requirements for rolling equipment appears. The increase of rolling speed and rolling force weakens the reliability of original equipment, and vertical vibration of the rolling mill appears in more and more fields. This kind of vibration will cause the thickness difference of the strip steel, which is no longer stable, or the surface of the strip steel will produce vibration marks, the surface quality will become poor [1], and even cause serious production accidents, such as strip breaking. It is difficult to deal with this kind of monitoring in the first time, and, it is hard to avoid vibration.

Objectives

Results

Conclusion