Characteristics of unsteady lubrication film in metal-forming process with dynamic roll gap

Abstract

Based on the theory of unsteady hydrodynamic lubrication and relevant mathematic and physical methods, a basic model was developed to analyze the unsteady lubrication film thickness, pressure stress and friction stress in the work zone in strip rolling. The distribution of pressure stress and friction stress in the work zone was obtained. A numerical simulation was made on a 1850 cold rolling mill. The influence of back tension stress and reduction on the distribution of pressure stress and friction stress between the roll gaps was qualitatively analyzed by numerical simulation. The calculated results indicate that the higher the back tension, the lower the pressure stress and the friction stress in the work zone, and the largest friction stresses are obtained at the inlet and outlet edges. The pressure and friction gradients are rather small at high back tension. The pressure-sensitive lubricant viscosity increases exponentially with the increase of pressure. The unsteady lubrication phenomenon in the roll bite is successfully demonstrated.

Keywords

metal-forming / interface / unsteady lubrication / dynamical roll gap / film characteristics

References

[1] ZhengY-j, XieZ-h, LiY-g, ShenG-x, LiuH-min. Spatial vibration of rolling mills [J]. Journal of Materials Processing Technology, 2013, 213(4): 581-588

[2] LiH-j, JiangZ-y, WeiD-bin. Crystal plasticity finite modeling of 3D surface asperity flattening in uniaxial planar compression [J]. Tribology Letters, 2012, 46(2): 101-112

[3] SunJ-l, PengY, LiuH-min. Non-linear vibration and stability of moving strip with time-dependent tension in rolling process [J]. Journal of Iron and Steel Research, International, 2010, 17(6): 11-15

[4] YangX, TongC-n, YueG-f, MengJ-ji. Coupling dynamic model of chatter for cold rolling [J]. Journal of Iron and Steel Research, International, 2010, 17(12): 30-34

[5] XiangJ, HeD, ZengQ-yuan. Effect of cross-wind on spatial vibration responses of train and track system [J]. Journal of Central South University of Technology, 2009, 16(3): 520-524

[6] SunC-gang. Investigation of interfacial behaviors between the strip and roll in hot strip rolling by finite element method [J]. Tribology International, 2005, 38(4): 413-422

[7] ZhangB, XuB-s, XuY, ZhangB-sen. Tribological characteristics and self-repairing effect of hydroxy-magnesium silicate on various surface roughness friction pairs [J]. Journal of Central South University of Technology, 2011, 18(5): 1326-1333

[8] StephanyA, PonthotJ P, ColletteC, SchelingsJ. Efficient algorithmic approach for mixed-lubrication in cold rolling [J]. Journal of Materials Processing Technology, 2004, 153/154(11): 307-313

[9] TieuA K, JiangZ-y, LuChen. A 3D finite element analysis of the hot rolling of strip with lubrication [J]. Journal of Materials Processing Technology, 2002, 125/126(9): 638-644

[10] BenasciuttiD, BrusaE, BazzaroG. Finite elements prediction of thermal stresses in work roll of hot rolling mills [J]. Procedia Engineering, 2010, 2(1): 707-716

[11] MohammadR F, ImanS, AmirH A. A comparative study of slab deformation under heavy width reduction by sizing press and vertical rolling using FE analysis [J]. Journal of Materials Processing Technology, 2009, 209(2): 728-736

[12] KangK, PelowC, WithamL. Analysis of changes in 3D surface texture anisotropy ratio parameter and friction during sheet rolling campaigns [J]. Wear, 2008, 264(5/6): 434-438

[13] GuoR, JiangS H, ChoiY H. Torsional vibration analysis of lathe spindle system with unbalanced workpiece [J]. Journal of Central South University of Technology, 2011, 18(1): 171-176

[14] XieH-b, JiangZ-y, YuenW Y D. Analysis of friction and surface roughness effects on edge crack evolution of thin strip during cold rolling [J]. Tribology International, 2011, 44(9): 971-979

[15] TieuA K, LiuY J. Friction variation in the cold rolling process [J]. Tribology International, 2004, 37(2): 177-183

[16] YunI S, WilsonW R D, EhmannK F. Review of chatter studies in cold rolling [J]. International Journal of Machine Tools and Manufacture, 1998, 38(12): 1499-1530

[17] SanieiM, SalimiM. Development of a mixed film lubrication model in cold rolling [J]. Journal of Materials Processing Technology, 2006, 177(1/2/3): 575-581

[18] WilsonW R D, ChangD F. Low speed mixed lubrication of bulk metal forming processes [J]. ASME Journal of Tribology, 1996, 118(1): 83-89

[19] ZhaoZ-yeMetal plasticity deformation and roll theory [M], 1996, Beijing, Metallurgical Industry Press: 96-98