Lihong Yuan

Simulation of roll grinding system dynamics with rotor equations and speed control

Abstract A nonlinear dynamical model for paper machine roll grinding process is investigated through a group of delay differential equations with one constant time-delay. In this model, the time-delay effect is originated from shape error traces on the surface of the roll. The contact interaction of the roll and the grindstone is based on the wear theory, and the lateral deformations of the roll as a simply supported continuous beam element inside a rotational coordinate frame and the rotational rigid body vibration system are considered. The PD-controllers of the roll and the grindstone drives are also included. The numerical simulations for time-history responses provide a view of the stability of this grinding process for the design, analysis and verification of industrial roll grinding measurements in future.

Stability Analysis of Roll Grinding System with Double Time Delay Effects

The grinding system of paper machine rolls is studied. The MDOF model with double time delays is used to describe the dynamical behavior of the system. By analyzing the simplified linear and non-linear models the stability characteristics of the system has been investigated by different stability methods. Numerical simulation results are used to illustrate stability behaviors of the models.

Active Vibration Control of Multibody Rolling Contact System

The aim of this work is to use multibody analysis to study rolling contact vibrations and then test the active control methods to eliminate these vibrations. The system considered is the rolling contact of two metal rolls. The contact is softened by using a thin polymer coating on one roll. The polymer cover generates a regenerative vibration source to the contact because the polymer does not recover fully before re-entering to the contact. This phenomenon creates a limit cycle vibration condition to the contact. The modeling of the system is based on the multibody dynamics. The metal rolls are modeled as super elements by using multibody equations and the component mode synthesis approach. The polymer cover is modeled analytically by giving an expression for the contact line load. The nonlinear stiffness of the cover is included. The regenerative vibration source is introduced to the system as a time delay term in the line load equations. The time domain responses are solved by using numerical time integration. The active vibration control is carried out by introducing external force actuators into the multibody model. The strategy is to create a feedback force with same magnitude and an opposite phase as the regenerative vibration source. As results the time domain responses of several different cases are compared and discussed.

Numerical Modeling of Paper Machine Roll Contact with Regenerative Out-Of-Roundness Excitation

The softened rolling contact of two paper machine rolls is considered. A regenerative excitation source can exists in the system due to the finite relaxation time of the roll cover polymer materials. The modeling of the rolls is described by multibody substructuring methodology and the polymer cover layer between the rolls in contact is modeled by contact spring reaction forces calculated according to the stiffness of the layer. The regenerative excitation is introduced to the system as a time delay term and it is calculated from the penetration history of the cover layer. The solution of the system equations is obtained by numerical time integration by utilizing the method of steps time delay equation solution procedure. Some numerical results are illustrated.

Design of Fuzzy Logic-Based Controller in Roll Grinding System With Double Regenerative Chatter

This paper proposes application of fuzzy logic control (FLC) to do vibration control for the roll-grinding machine system with double regenerative chatter. In this paper, a multiple-degree-of-freedom (MDOF) model is developed to represent the dynamics behaviors of this kind of system. The dynamic system has double delays and lumped cutting parameters which make vibration control challenging. Numerical simulation shows that FLC can dramatically reduce the vibration levels compared to a convention control method.Copyright

Stability Analysis of Roll Grinding Delay System

Abstract In this paper the stability of a roll grinding delay system is studied. This delay system is characterised with a negative feedback and large imaginary parts in its poles. The authors analysed its stability by using the Nyquists criterion. Time domain simulations were used for the verification of the stability analyses.

Numerical simulation of dynamic rolling contact including delay effect from cover layer

Abstract The numerical solution of a rolling contact dynamics of two paper machine rolls is discussed. The delay effect of a polymer roll cover layer is included in the system and the vibrations of the contact are studied. The stability of a test delay case is determined by time domain analyses

Delay effect from roll cover polymer material in paper finishing units

Abstract In this paper the dynamics of a roll-nip system in paper finishing units in the case of polymer covered roll is studied. The delay effect which provides an important additional effect on roll deformation and vibration of the system has been taken into account. The dynamical behavior of this system has been analysed in frequency domain and time domain.