Stochastic Method to Predict Effects of Roll Grinding Deviations on Sheet Flatness in Cold Rolling

2021 ◽  
pp. 1-34
Author(s):  
Feng Zhang ◽  
Arif S Malik
Keyword(s):  
Random Field ◽  
Contact Region ◽  
Measurement Data ◽  
Work Roll ◽  
Rolling Process ◽  
Rolled Sheet ◽  
Field Problem ◽  
Sheet Rolling ◽  
Roll Axis ◽  
Work Rolls

Abstract Industrial measurements of the diameter profiles of work-rolls used in cold sheet rolling are applied with a stochastic roll-stack model to better understand how residual error from the roll grinding process affects the rolled sheet flatness quality. Roll diameter measurements taken via a non-contact, optical device on new, warm, and worn work-rolls show that the diameter deviations vary along the roll lengths, across roll samples, and at different operational states, suggesting a multi-dimensional random field problem. Studies are conducted for a 4-high rolling mill with 301 stainless steel sheet to investigate the reliability in achieving target flatness considering the work-roll diameter random field. Also investigated is the sensitivity of the flatness reliability to roll diameter deviations at different locations along the roll lengths, and for the three operational states (newly machined, warm, and worn following several passes). The results lead to several key findings. Foremost, it is shown that an assumption of statistical independence among the residual grinding errors at different roll axis locations is improper. Further, it is demonstrated that, for the measured grinding error correlation patterns, the roll diameter deviations external to the roll/sheet contact region play an important role in contributing to flatness defects within the sheet, and that these influences vary according to the roll operational state (new, warm, worn). The presented stochastic model and applied measurement data thus provide for a new understanding into how roll grinding performance influences dimensional quality in the sheet rolling process.

Determination of Thermal Parameters of a Work-Roll in Warm Rolling Using Inverse Modeling

2018 ◽  
Author(s):  
Vinod Yadav
Keyword(s):  
Inverse Method ◽  
Work Roll ◽  
Rolling Process ◽  
Thermal Parameters ◽  
Shop Floor ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients ◽  
Work Rolls

Thermal parameters of a work-roll play an important role in the modeling of the rolling process, due to periodic thermal loading. The knowledge of thermal parameters is also vital in understanding the fatigue life of the work-roll and the thermal crown. However, estimation of the thermal parameters viz., thermal conductivity, thermal diffusivity and convective heat transfer coefficients at both, inner and outer roll periphery is tough to realize during the rolling process. Various methods employed earlier for measuring the thermal properties of work-rolls in the rolling process requires intrusion in the surface of the work-rolls, mainly to embed the thermocouples inside the rolls. These methods are easy to implement, but it is really hard to achieve truthful estimation. A possible way out is to measure the average thermal parameters of a work roll in the rolling process by utilizing the measured temperature at two specified locations on the work-roll surface. In this work, an inverse method is proposed to estimate the thermal properties and convective heat transfer coefficients of a roll in the rolling process. The inverse method makes use of a direct model of temperature determination considering plane strain problem, which is based on the integral transform method. For minimizing the error between the computed and experimentally recorded data, a quasi-Newton method is used. In lieu of shop floor experiments, a finite element method (FEM) based package ABAQUS 6.10 is used to obtain the temperature distribution in the work-roll. Further, an additive white Gaussian error is added in the FEM simulated measurements to assess the inverse method for stability towards mild measurements. The inverse estimation is successfully validated and can be used in shop floor for the online determination of thermal parameters of the work-rolls in the rolling process.

Mathematical Model for Temperature Distributions of Work Roll in Aluminum Strip Cold Rolling

2010 ◽  
Vol 150-151 ◽  
pp. 97-101
Author(s):  
De Dong Gao ◽  
Shan Wang
Keyword(s):  
Temperature Distribution ◽  
Cold Rolling ◽  
Contact Region ◽  
Work Roll ◽  
Rolling Process ◽  
Backup Roll ◽  
Friction Heat ◽  
Roll Pressure ◽  
Temperature Distributions ◽  
Aluminum Strip

The temperature distribution of the work roll affects the shape and size of final product in aluminum strip cold rolling process. The segmental model is presented to explore the boundaries of the roll. The surface of the work roll is divided into 5 different regions including the outlet roll-strip contact region, the inlet roll-strip contact (bite) region, the roll-spray region, the roll-air region and the roll-roll contact region. Based on the analysis of the roll pressure, the mathematical models of the plastic doformation work and friction heat are proposed to calculate the temperature variation in bite region. The boundaries, including heat convection with lubricant/air and heat conduction with the backup roll, are considered to model the work roll’s temperature distribution.

DYNAMIC CHARACTERISTICS OF SHEET ROLLING INSTABILITY

2002 ◽  
Vol 02 (03) ◽  
pp. 375-394 ◽  
Author(s):  
Y.-J. LIN ◽  
C. S. SUH ◽  
S. T. NOAH
Keyword(s):  
Plastic Deformation ◽  
Dynamic Instability ◽  
Dominant Role ◽  
Physical Phenomenon ◽  
Spectral Characteristics ◽  
Work Roll ◽  
Rolled Strip ◽  
Sheet Rolling ◽  
Spectral Components ◽  
Work Rolls

Dynamic rolling instability known as fifth-octave chatter is studied using a nonlinear model developed to describe the responses of work rolls subjected to the exertion of sheet forces of various spectral characteristics. The model enables the dynamic instability of sheet rolling to be correlated with work roll stiffness, rolling speed, inter-stand tension, roll-bite entry and exit thickness, and the sheet force resulted from the interactive action of the work roll with the plastic deformation of the rolled strip. It is found that roll-bit elastic-plastic deformation sheet force is nonlinearly coupled with the rollstack stiffness and also plays a dominant role in affecting rolling instability. In addition, whenever the frequency spectrum of the normal sheet forces containing spectral components that match the fundamental modes of the roll stand, resonance-like beating would occur. This highly linear physical phenomenon, which is accompanied by large vibration amplitudes in the active work rolls, is recognized as chatter. Although many different dynamic modes of instability including mode excitation and beating are induced in response to sheet forces of nonlinear and non-stationary in nature, however, the rolling system never responds chaotically.

An Investigation of the Effect of Speeds of Work Rolls on Rolling Strip

1995 ◽  
Vol 117 (3) ◽  
pp. 341-346 ◽  
Author(s):  
Zone-Ching Lin ◽  
Y. C. Cheng
Keyword(s):  
Hot Rolling ◽  
Rolling Force ◽  
Large Strain ◽  
Work Roll ◽  
Rolling Process ◽  
Analysis Model ◽  
Hot Rolling Process ◽  
Rolling Strip ◽  
Work Rolls ◽  
Thermoelastic Plastic

The paper is an investigation of strip curvature caused by the different speeds between the upper work roll and the lower work roll in the rolling process for an aluminum strip. At the same time, we analyzed the variations in the temperature field and strain field, and used a method of speeds variation of the upper and lower work rolls to calibrate the deformation curvature caused by the coolant condition in the hot rolling process. Based on the large deformation-large strain theory, and by means of the Updated Lagrangean Formulation (ULF) and increment theory, a coupled thermoelastic-plastic analysis model for hot rolling process is thus constructed. At the same time the finite difference method was also used to solve the transient heat transfer equation. Finally, the numerical analysis method developed in this study was employed to analyze the changes in the aluminum strip’s temperature and other changes during rolling. In addition, the average rolling force obtained from the simulation was compared with that from the experiments. It verified that the model in this study is reasonable.

scholarly journals Experimental study of horizontal impact forces acting on equipment of thick sheet rolling stands during rolling

2018 ◽  
Vol 239 ◽  
pp. 01041 ◽  
Author(s):  
Anatoliy Ishchenko ◽  
Viktor Artiukh ◽  
Vladlen Mazur ◽  
Albina Calimgareeva ◽  
Miroslava Gusarova
Keyword(s):  
Experimental Data ◽  
Experimental Studies ◽  
Work Roll ◽  
Thick Sheet ◽  
Sheet Rolling ◽  
Technical Aspects ◽  
Rolling Mills ◽  
Impact Forces ◽  
Technical Solutions ◽  
Work Rolls

Technical aspects, methods and results of experimental studies of reversing rolling stands details horizontal accelerations of thick sheet rolling mills 3000 and 3600 are shown. Sequence of horizontal movements of bottom work roll with chocks in windows of housings during normal metal-in, steady rolling and metal-out is given. Usage of obtained experimental data and calculation of horizontal forces of work rolls chocks impacts against housings provided execution of stress calculations of technical solutions for increase of rolling stands durability.

scholarly journals On the Evolution of Temperature and Combined Stress in a Work Roll under Cyclic Thermo-Mechanical Loadings during Hot Strip Rolling and Idling

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5054
Author(s):  
Kejun Hu ◽  
Qinghe Shi ◽  
Wenqin Han ◽  
Fuxian Zhu ◽  
Jufang Chen
Keyword(s):  
Thermal Stress ◽  
Hot Rolling ◽  
Work Roll ◽  
Rolling Process ◽  
Roll Surface ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Hot Strip ◽  
Calculation Results ◽  
Work Rolls

An accurate prediction of temperature and stress evolution in work rolls is crucial to assess the service life of the work roll. In this paper, a finite element method (FEM) model with a deformable work roll and a meshed, rigid body considering complex thermal boundary conditions over the roll surface is proposed to assess the temperature and the thermal stress in work rolls during hot rolling and subsequent idling. After that, work rolls affected by the combined action of temperature gradient and rolling pressure are investigated by taking account of the hot strip. The accuracy of the proposed model is verified through comparison with the calculation results obtained from the mathematical model. The results show that thermal stress is dominant in the bite region of work rolls during hot rolling. Afterwards, the heat treatment residual stresses which are related to thermal fatigue are simulated and introduced into the work roll as the initial stress to evaluate the redistribution under the thermal cyclic loads during the hot rolling process. Results show that the residual stress significantly changed near the roll surface.

Two-Dimensional Transient Thermal Behavior of Work Rolls in Rolling Process

1998 ◽  
Vol 120 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Remn-Min Guo
Keyword(s):  
Boundary Conditions ◽  
Complete Solution ◽  
Work Roll ◽  
Rolling Process ◽  
Related Individual ◽  
Various Boundary Conditions ◽  
Cooling Behavior ◽  
Friction Energy ◽  
Transient Thermal ◽  
Work Rolls

In the rolling process, deformation and friction energy generated in the roll bite transfer to work rolls. Work rolls are cooled by the cooling medium in both entry and exit sides of the mill. The transient cooling behavior of the roll affects the temperature distribution and the thermal profile. This article proposes a semi-analytical solution to solve the temperature field of the work roll which is subjected to various cooling and heating boundary conditions during a rolling campaign. Laplace and inverse transforms are applied to pursue the unsteady solution for one particular boundary condition. The complete solution for various boundary conditions is superimposed by related individual solutions using Duhamel’s rule. Case studies as demonstrated in this paper show versatility of the developed model.

On the Causes of Rolling Instability and Chatter

2002 ◽  
Author(s):  
Yun-Jeng Lin ◽  
C. Steve Suh ◽  
Sherif T. Noah
Keyword(s):  
Plastic Deformation ◽  
Dynamic Instability ◽  
Dominant Role ◽  
Physical Phenomenon ◽  
Spectral Characteristics ◽  
Work Roll ◽  
Rolled Strip ◽  
Sheet Rolling ◽  
Spectral Components ◽  
Work Rolls

Dynamic rolling instability known as fifth-octave chatter is studied using a nonlinear model developed to describe the responses of work rolls subjected to the exertion of sheet forces of various spectral characteristics. The model enables the dynamic instability of sheet rolling to be correlated with work roll stiffiness, rolling speed, inter-stand tension, roll-bite entry and exit thickness, and the sheet force resulted from the interactive action of the work roll with the plastic deformation of the rolled strip. It is found that roll-bit elastic-plastic deformation sheet force is nonlinearly coupled with the rollstack stiffness and also plays a dominant role in affecting rolling instability. In addition, whenever the frequency spectrum of the normal sheet forces containing spectral components that match the fundamental modes of the roll stand, resonance-like beating would occur. This highly linear physical phenomenon, which is accompanied by large vibration amplitudes in the active work rolls, is recognized as chatter. Although many different dynamic modes of instability including mode excitation and beating are induced in response to sheet forces of nonlinear and non-stationary in nature, however, the rolling system never responds chaotically.

A Study on Corrosion Wear of Cold Rolling Work Roll

2013 ◽  
Vol 871 ◽  
pp. 152-158
Author(s):  
Wei Hua Sun ◽  
Hong Chun Li ◽  
Ahn Kiet Tieu
Keyword(s):  
Cold Rolling ◽  
Corrosive Wear ◽  
Work Roll ◽  
Rolling Process ◽  
Corrosion Wear ◽  
Roll Surface ◽  
Steel Rolling ◽  
Conductive Medium ◽  
Materials Used ◽  
Work Rolls

The MMS-2B wear machine was used to study abrasion wear of work rolls in cold rolling by simulating emulsion cooling during the cold rolling process. The work roll materials used were 4%Cr, same as those in industrial production. The surface SEM scanning photographs were taken every 30 minutes until the friction experiment finished, and erosive appearance of emulsion on the work roll surface could be seen in the photos. The corrosive wear of the work roll surface is discussed. Findings show that the main causes of stress corrosion and pitting corrosion are uneven microstructure on the work roll surface and a large number of dislocation accumulations, which form microscopic cells. Water in steel rolling emulsion is the main conductive medium of electrochemistry reaction, and this intensifies the corrosive wear.

Theoretical Study of the Dynamic Effects Based on Work-Roll Model in Metal Sheet Rolling Process

2012 ◽  
Vol 538-541 ◽  
pp. 595-600
Author(s):  
Qiao Yi Wang ◽  
Yao Zhu ◽  
Rui Jin Gao ◽  
Yong Zhao
Keyword(s):  
Analytical Model ◽  
Dynamic Instability ◽  
Work Roll ◽  
Rolling Process ◽  
Metal Sheet ◽  
Backup Roll ◽  
Sheet Rolling ◽  
Linear Elastic ◽  
Nonlinear Analytical Model ◽  
Roll Bite

A new analytical model for the configuration of a four-high rolling mill stand is proposed in this article. Using the model, the dominant sources of stiffness in the fifth octave and the third octave models are identified. The assumptions made for the derivation of the model are that the work rolls are isotropic linear elastic, that there is no gap or separation between the work roll and the backup roll at all times. In addition, only the vertical interactions of the work roll and the roll-bite are considered. The nonlinear characteristics of this dynamic system are contributed from the contact area of the work roll and the backup roll. Analyses show that the natural frequency of the nonlinear analytical model matches the fifth octave rolling chatter, and the dominant parameters of the dynamic instability are characterized. The effects of inter-stand tensions, rolling speeds, friction between the work roll and the metal sheet roll-bite, and the thickness of the metal sheet on rolling chatter are discussed in the analysis of the dynamics of the rolling model.

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