Development of Mixed Lubrication Cold Rolling Model

2015 ◽  
Vol 642 ◽  
pp. 190-195
Author(s):  
Yhu Jen Hwu ◽  
Jian Ting Lee ◽  
Yeau Ren Jeng
Keyword(s):  
Cold Rolling ◽  
High Surface ◽  
Work Roll ◽  
Mixed Lubrication ◽  
Rolled Strip ◽  
Base Oil ◽  
Roll Deformation ◽  
Inlet Zone ◽  
Quality Surface ◽  
Roll Bite

Within past 20 years, high surface qualities of cold strip were demanded by automotive industry and electrical engineering. Main purposes of cold rolling processed are to provide high quality surface and generate appropriate roughness for different customs. Emulsion is a common coolant used in cold rolling processes, Properties of base oil in emulsion, concentration, roughness of work roll, rolling speed and reduction are important parameters, which dominate the surface qualities of cold rolled strip. Hence, a powerful cold rolling model which can describe complicate tribological behavior in roll bite is required. In this article, a cold rolling model which integrates roll deformation and mixed lubrication in inlet zone and biting area was developed. The thickness of oil film, fraction of contact area and coefficient of friction in roll bite are calculated.

Mixed Lubrication Model for Cold Rolling Considering the Inlet and Deformation Zones

2012 ◽  
Author(s):  
Martin Bergmann ◽  
Klaus Zeman ◽  
Alexander Kainz ◽  
Konrad Krimpelstätter ◽  
Dieter Paesold ◽  
...  
Keyword(s):  
Cold Rolling ◽  
Film Formation ◽  
Mixed Lubrication ◽  
Bulk Deformation ◽  
Metallic Surfaces ◽  
Hydrodynamic Friction ◽  
Plastic Strip ◽  
Coupled Equations ◽  
Inlet Zone ◽  
Raphson Method

A mixed lubrication model for cold rolling was developed by separating, according to common concepts, the domain of calculation into two zones: the inlet zone and the zone of plastic strip bulk deformation. The analysis of the inlet zone mainly focuses on film formation from different lubricants based on the evolution of layers consisting of neat oil on the metallic surfaces. In the zone of plastic strip bulk deformation, contributions of boundary and hydrodynamic friction are modeled incorporating longitudinal and transversal roughness components. Lubricant pressure, which is influenced by the geometry of these roughness structures, is governed by hydrodynamic mechanisms. Additionally, lubricant temperature in the roll bite is predicted by an integrated thermodynamics sub-model. While coupling between the inlet and plastic deformation zones is performed iteratively, the highly non-linear and coupled equations for the latter zone are solved simultaneously by applying a variant of the well-known damped Newton-Raphson method.

scholarly journals Ultrasonic roll bite measurements in cold rolling: Contact length and strip thickness

2017 ◽  
Vol 232 (2) ◽  
pp. 179-192 ◽  
Author(s):  
Yves Carretta ◽  
Andrew Hunter ◽  
Romain Boman ◽  
Jean-Philippe Ponthot ◽  
Nicolas Legrand ◽  
...  
Keyword(s):  
Cold Rolling ◽  
Rolling Mill ◽  
Work Roll ◽  
Contact Length ◽  
Strip Thickness ◽  
Rolling Contact ◽  
Thickness Variation ◽  
Rolling Load ◽  
Process Measurements ◽  
Roll Bite

In cold rolling of thin metal strip, contact conditions between the work rolls and the strip are of great importance: roll deformations and their effect on strip thickness variation may lead to strip flatness defects and thickness inhomogeneity. To control the process, online process measurements are usually carried out; such as the rolling load, forward slip and strip tensions at each stand. Shape defects of the strip are usually evaluated after the last stand of a rolling mill thanks to a flatness measuring roll. However, none of these measurements is made within the roll bite itself due to the harsh conditions taking place in that area. This paper presents a sensor capable of monitoring strip thickness variations as well as roll bite length in situ and in real time. The sensor emits ultrasonic pulses that reflect from the interface between the roll and the strip. Both the time-of-flight of the pulses and the reflection coefficient (the ratio of the amplitude of the reflected signal to that of the incident signal) are recorded. The sensor system was incorporated into a work roll and tested on a pilot rolling mill. Measurements were taken as steel strips were rolled under several lubrication conditions. Strip thickness variation and roll-bite length obtained from the experimental data agree well with numerical results computed with a cold rolling model in the mixed lubrication regime.

On the Characteristics and Mechanism of Rolling Instability and Chatter

2003 ◽  
Vol 125 (4) ◽  
pp. 778-786 ◽  
Author(s):  
Y.-J. Lin ◽  
C. S. Suh ◽  
R. Langari ◽  
S. T. Noah
Keyword(s):  
Work Roll ◽  
Rolling Speed ◽  
Effective Control ◽  
Rolled Strip ◽  
Strip Rolling ◽  
Dynamical Interaction ◽  
Rolling Mills ◽  
Roll Mill ◽  
Highly Nonlinear ◽  
Roll Bite

A nonlinear model describing the dynamical interaction between work rolls and metal sheets and the initiation of fifth octave rolling chatter is presented. The model, which comprises a work roll sub-model and a metal sheet roll-bite sub-model, enables the instability of strip rolling to be qualitatively and quantitatively studied as a function of rollstack 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 concluded that, even though the governing dynamics is highly nonlinear, rolling chatter instability is none other than mode excitation or beating, and thus linear. Analyzed results correspond well with what have been observed in physical rolling mills. Specifically, the natural frequency predicted for a 4-H rolling stand fits the fifth octave chatter at 550∼650 Hz and there is a critical rolling speed (2.54 m/sec for the material and sheet configurations considered in the paper) beyond which rolling instability will occur. This research establishes the fundamental knowledge base required for the understanding of chatter characteristics and mechanism, and thus provides the essential bases for effective control of rolling instability and chatter-free roll mill design.

Two-Dimensional Roll Bite Model with Lubrication for Cold Strip Rolling

2014 ◽  
Vol 966-967 ◽  
pp. 48-62 ◽  
Author(s):  
Talib Dbouk ◽  
Pierre Montmitonnet ◽  
Nicolas Legrand
Keyword(s):  
Mixed Lubrication ◽  
Test Cases ◽  
Slab Method ◽  
Strip Rolling ◽  
Micro Fluidics ◽  
Lubricant Flow ◽  
New Type ◽  
Roll Deformation ◽  
Cold Strip Rolling ◽  
Roll Bite

To help optimize cold rolling operations, mixed lubrication models have been developed and embedded in roll bite models. The resulting models combine micro-fluidics in a porous medium (the lubricant flow between the contacting rough surfaces), microplasticity (roughness flattening / scratching), macro-plasticity (strip reduction) and roll thermo-elasticity. They are therefore really complex and need a lot of physical data. Based on previous developments, a new, simpler version of our lubrication model has been coupled with a new roll bite model recently presented: slab method for the strip elastic-plastic deformation (Prandtl-Reuss equations), a complete influence functions set for the roll deformation with circumferential displacements, and an efficient, adaptive relaxation technique when iterating between roll and strip models. The lubrication model is elaborated on Wilson and Sheu’s mixed lubrication model. The paper describes the implementation and compares its results with our previous, more complex version; a reasonable agreement is found. Several test cases of increasing difficulty show the robustness of the model and of its implementation. As a conclusion, a brief perspective is provided on how this new type of roll bite model could be used in industry.

Taper Roll Contour Design for Edge Drop Control of Non-Oriented Electrical Steel on Tandem Cold Rolling Mill

2012 ◽  
Vol 166-169 ◽  
pp. 670-673
Author(s):  
Guang Hui Yang ◽  
Jie Zhang ◽  
Hong Bo Li ◽  
Jian Guo Cao ◽  
Sheng Hui Jia
Keyword(s):  
Cold Rolling ◽  
Local Stress ◽  
Element Model ◽  
Work Roll ◽  
Contour Length ◽  
Rolled Strip ◽  
Backup Roll ◽  
Tandem Cold Rolling ◽  
Pressure Peak ◽  
Edge Drop

The taper work roll of the 1700 mm tandem cold rolling mills had some problems in the course of using, and the taper roll contour was ground difficultly and the difference between the designed contour and grinding contour was very big, and the work roll and backup roll had very serious and non-uniform roll wearing and even often had roll spalling, and above those problems affected the stability of rolling process seriously. After analyzing the structure and contour of the taper work roll, it was found that the work roll contour was designed unreasonably and the straight line part and the edge drop control part of roll contours were not connected smoothly, and so it lead to the local stress concentration easily in the transition region and a bigger contacting pressure peak between work roll and backup roll appeared. On basis of decreasing the contacting pressure peak and taking the width of rolled strip and the grinding contour length change into consideration, the design method of the edge control contour part of the taper roll was put forward. The finite element model was built with the software ANASYS9.0 to analyze the mill shape adjusting characteristics, and the simulation result showed that the newly-designed taper roll contour could improve the mill shape adjusting ability. It was shown in the rolling trial that the strip edge drop average was decreased from 14.9μm to 7.5μm and the edge drop fluctuation of strip was restrained to some extent and controlled within ±3μm.

Development of special lubricant for the copper belt cold rolling

2016 ◽  
Vol 68 (5) ◽  
pp. 586-590 ◽  
Author(s):  
Fuchuan Huang ◽  
Fukang Deng ◽  
Kang-Chun Li ◽  
Ke Qin
Keyword(s):  
Cold Rolling ◽  
Oxidation Resistance ◽  
High Speed ◽  
Orthogonal Experiment ◽  
High Surface ◽  
Chemical Properties ◽  
Content Type ◽  
Base Oil ◽  
High Surface Quality ◽  
Physical And Chemical

Purpose Aiming at the high temperature, high speed, high precision and high surface quality of the copper belt cold rolling, the purpose of this paper is to develop a new type of lubricant for cold rolled copper belt. Design/methodology/approach The component of the developed oil was determined based on the physical and chemical properties of the base oil and the tribological properties, the oxidation resistance properties, the rust resistance properties, the anti-foam properties, the demulsibility and the other properties of the additives. The orthogonal experiment method was used to determine the optimum adding amount of the additives; finally, the developed oil formulation was determined. Findings The physical and chemical experiment results show that the developed oil has a good performance of oil film bearing capacity and oxidation resistance. The simulation of rolling experiment found that the developed oil can significantly reduce rolling pressure and effectively reduce the friction in the process of rolling. Originality/value The experimental results show that the developed oil has excellent performance and can meet the requirement of lubrication in the process of cold rolling copper belt.

Experimental study on wear and friction of work roll material with 4% Cr and added Ti in cold rolling

Wear ◽  
2011 ◽  
Vol 271 (9-10) ◽  
pp. 2500-2511 ◽  
Author(s):  
H.C. Li ◽  
Z.Y. Jiang ◽  
A.K. Tieu ◽  
W.H. Sun ◽  
D.B. Wei
Keyword(s):  
Experimental Study ◽  
Cold Rolling ◽  
Work Roll ◽  
Wear And Friction

scholarly journals Silicon Steel Strip Profile Control Technology for Six-High Cold Rolling Mill with Small Work Roll Radius

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 401
Author(s):  
Hainan He ◽  
Jian Shao ◽  
Xiaochen Wang ◽  
Quan Yang ◽  
Xiawei Feng
Keyword(s):  
Cold Rolling ◽  
Rolling Mill ◽  
Steel Strip ◽  
Work Roll ◽  
Rolling Process ◽  
Silicon Steel ◽  
Cold Rolling Mill ◽  
Strip Profile ◽  
Profile Control ◽  
Small Work

Due to the requirement of magnetic properties of silicon steel sheets, producing high-precision size strips is the main aim of the cold rolling industry. The tapered work roll shifting technique of the six-high cold rolling mill is effective in reducing the difference in transverse thickness of the strip edge, but the effective area is limited, especially for a high crown strip after the hot rolling process. The six-high mill with a small work roll size can produce a strip with higher strength and lower thickness under a smaller rolling load. At the same time, the profile of the strip can be substantially improved. By advancing a well-established analytical method, a series of simulation analyses are conducted to reveal the effectiveness of a small work roll radius for the strip profile in the six-high cold rolling process. Through the analysis of flattening deformation and deflection deformation on the load, the change rule of the strip profile produced by the work roll with a small roll diameter can be obtained. Combined with theoretical analysis and industrial experiments, it can be found that the improvement effect of the small work roll radius on the profile of the silicon strip is as significant.

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