scholarly journals Nonlinear Torsional Vibration Dynamics Behaviors of Rolling Mill’s Multi-DOF Main Drive System under Parametric Excitation

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Dongying Han ◽  
Peiming Shi ◽  
Kewei Xia
Keyword(s):  
Torsional Vibration ◽  
Joint Angle ◽  
Rolling Process ◽  
Nonlinear Damping ◽  
Drive System ◽  
Nonlinear Stiffness ◽  
Coupled Equations ◽  
Principal Coordinates ◽  
Damping Torque ◽  
Main Drive System

Considering the influence caused by joint angle, nonlinear damping, and nonlinear rigidity, the nonlinear torsional vibration dynamical modeling of the multi-DOF rolling mill’s main drive system is established. To analyze the coupled equations by analytic method, the equations are decoupled by transforming them into principal coordinates. The amplitude-frequency characteristic equations are obtained by multiscale method. Furthermore, numerical example based on the 1780 rolling mill’s main drive system of some Steel Co. is given to illustrate the effects of the resonance on the response of the system. The relationship between amplitude and frequency varies according to the parameters changes of nonlinear stiffness, nonlinear friction damping, torque disturbance, and joint angle. During the rolling process, the limited joint angles range is obtained and the variation rules of the joint angle caused by the nonlinear damping, nonlinear stiffness, and the disturbance torque are gained. The results present that the rolling mill can work more stably with the joint angle at a range from 2° to 8° by controlling the value of parameters. The research results provide a theoretical basis and reference for analyzing torsional vibration of rolling mill’s transmission system caused by joint angle.

Torsional Vibration Analysis of Drive System for 6-High Cold Rolling Mill

2013 ◽  
Vol 721 ◽  
pp. 572-578
Author(s):  
Yu Hou ◽  
Zhi Jing Zhang ◽  
Yan Xia Guo ◽  
Jiu Qiang Feng ◽  
Jie Luo
Keyword(s):  
Cold Rolling ◽  
Torsional Vibration ◽  
Rolling Mill ◽  
Weak Link ◽  
Drive System ◽  
Cold Rolling Mill ◽  
Vibration Model ◽  
The Impact ◽  
Main Drive System ◽  
Biting Time

The torsional vibration model of main drive system for 6-high cold rolling mill was established. Calculation formula of torque amplification factor (TAF) of main drive system was put forward when the clearance exists or not. The TAF-curve, changing by the biting time of blank, was drawn, and whether torsional vibration could cause mechanical failure in weak link of main drive system was judged. The TAF variation with the biting time of blank was analyzed when the clearance exists. The method to reduce TAF was proposed before the clearance was eliminated, and the effect caused by the impact on main drive system was alleviated.

Effects of Temperature and Cross Section Variations on the Vibrational Behavior of Finished Wire Blocks

2014 ◽  
Vol 622-623 ◽  
pp. 95-102
Author(s):  
Mohammadzaman Savari ◽  
Paul Josef Mauk ◽  
Oberrat Bernhardt Weyh
Keyword(s):  
Product Quality ◽  
Torsional Vibration ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Equation System ◽  
Rolling Process ◽  
Essential Elements ◽  
Lagrange Equations ◽  
Cross Sectional ◽  
Coupled Equations

Because of the great speed range in a finishing block of a wire rod mill, the reduction of torsional vibrations makes it possible to achieve closer rolling tolerances. The components transmitting the torque like gear box, coupling etc. can generate non-smooth or alternating torques which affect the product quality. To study the influences of torsion vibrations on the product quality, the dynamic interactions of the block and rolling process are simultaneously analyzed by a simulation model. As an example, a three stand arrangement is considered. The real transmission system is idealized as a structurally discrete torsional vibration model. The generalized rotational coordinates with a large number of rotational degrees of freedom can be reduced among others constants by means of gear ratios. Euler-Lagrange equations are applied to create the coupled equations of motion, which together constitute an ordinary differential equation of order 28. The rolling and main drive torques are defined as excitation for vibration on the right side of the equation system. A DC motor is selected as main drive and the voltage circuit equation of motor is integrated into the system of differential equations. The armature current and its interaction are consequently simulated. The rotational speed of rolls and motor, as well as roll torques, longitudinal stresses in rod and section widths are shown in diagrams as the result and thereby the torsional vibration of the essential elements of the system are studied for different temperatures and cross-sectional variations.

scholarly journals Robust Backstepping Control for Cold Rolling Main Drive System with Nonlinear Uncertainties

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Xu Yang ◽  
Kai-xiang Peng ◽  
Chao-nan Tong
Keyword(s):  
Cold Rolling ◽  
High Speed ◽  
Linear Time ◽  
External Disturbance ◽  
Rolling Process ◽  
Drive System ◽  
Disturbance Attenuation ◽  
Parameter Uncertainties ◽  
Robust Controller ◽  
Main Drive System

The nonlinear model of main drive system in cold rolling process, which considers the influence with parameter uncertainties such as clearance and variable friction coefficient, as well as external disturbance by roll eccentricity and variation of strip material quality, is built. By transformation, the lower triangular structure form of main drive system is obtained. The backstepping algorithm based on signal compensation is proposed to design a linear time-invariant (LTI) robust controller, including a nominal controller and a robust compensator. A comparison with PI controller shows that the controller has better disturbance attenuation performance and tracking behaviors. Meanwhile, according to its LTI characteristic, the robust controller can be realized easily; therefore it is also appropriated to high speed dynamic rolling process.

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