• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.349-355
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• 1999

The texture inhomogeniety during rolling is one of the greatest problems. Especially, shear texture develops more easily during ferritic rolling of steel sheets at high temperatures due to friction between rolls and the material. In this study, the influence of front and back tensions on the texture development during ferritic rolling has been studied. The rolling textures were simulated using the full constrains Taylor-Bishiop-Hill model with the strain history obtained from finite element analysis. The calculated textures showed that the back tension rolling could reduce the shear component more effectively than front tension or rolling without tension. However, the experimental results showed that the lension effect was very small compared to our prediction. It might be attributed to initial texture and difference in frictions between simulation and experiments.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.215-217
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• 2004

In order to obtain the initial starting sample having a random texture and fine grains, aluminum alloy 3103 sheets were repeatedly deformed by CCSS up to six passages and subsequently annealed at $300^{\circ}C$ for 1h. These samples were cold rolled at room temperature and also warm rolled at $250^{\circ}C$. Changes in rolling temperature gave rise to the different texture evolution. Warm rolling led to the pronounced texture gradients comprising the shear texture at the surface and the rolling texture at the sheet center. The formation of the rolling texture components, i.e., the ${\beta}$-fiber, was promoted by cold rolling than warm rolling.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.04a
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• pp.237-242
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• 1991

Shape rolling has been studied experimentally by many researchers. As large numbers of process variables are involved and the material flow is difficult to analyze in shape rolling, the use of numerical techniques as an engineering tool becomes extremely attractive. The first numerical approach to the three-dimensional plastic deformation of rolling was to investigate side spread in flat rolling. Oh and Kobayashi conducted a pioneering study in this field by applying an extremum principle for rigid, perfectlyplastic materials combined with the numerical computation. Since then, several other researchers have used three-dimensional finite element method for analysing spread in rolling . In this investigation of shaperolling al the computer simulations of shape rolling were conducted using TASKS. To verify the predictive capabilities of TASKS the first example chosen was square-to-round shape rolling

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.139-142
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• 2005

Cu-Ni-Zr-Ti bulk amorphous thin strips were produced by multi-pass warm rolling of the amorphous powder at temperatures in the supercooled liquid region. Process variables for rolling of the bulk amorphous strips were properly controlled to prevent onset of crystallization and failure during rolling up to three passes. During rolling of the amorphous powder, both the deformation and densification took place and the newly developed surface on the deformed amorphous particles enhances the consolidation leading to an increase in the strength. The strain state during rolling was analyzed by FEM.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.210-215
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• 1997

The development of rolling texture is dependent on the various rolling condition. And the geometry of rolling gab and the friction between rolls and rolled material mainly affect the type and sharpness of texture inhomogeneity through thickness. In order to follow the effect of geometry and friction various strain/pass and lubrication condition were applied during cold rolling. In this investigation various strain/pass and lubrication were applied during cold rolling in order to follow the effect rolling gap geometry and friction. More high 1/h was, more weak the ${\beta}$-fiber was and in the condition of l/h > 5 {001}<110> shear texture developed. In adition, rolling without lubrication enhanced the shear texture.

• Journal of Welding and Joining
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• v.34 no.6
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• pp.20-27
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• 2016

This study deals with the proper conditions of the trail rolling method (TRM) for the prevention of the buckling welding distortion at the AA5083 GMA butt weldment. For it, the effect of the working conditions of TRM including the rolling depth and the rolling distance between the welding torch and the roller on the longitudinal welding shrinkage force of the weldment was evaluated by using 3 dimensional thermo-mechanical FE analyses. The longitudinal welding shrinkage force inducing the buckling welding distortion at the GMA butt weldment was mitigated with an increase in the rolling depth and the rolling distance between the welding torch and the roller. Based on the results, the proper conditions of trail rolling method were established to reduce the longitudinal welding shrinkage force of the GMA butt weldment to below the critical value corresponding to the bucking distortion.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.124-129
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• 2011

The thick plate produced by rolling process is used as the basic members of a ship structure. In this paper, we present a setup model to control the asymmetric factors causing plate bending in the upper or lower direction during rolling. A series of finite element analysis are conducted to predict the relationship between various asymmetric factors and plate bending. The setup model is developed by regressing the relationship to the linear equations with several non-dimensional parameters. The setup model is verified by a pilot rolling test and applied to actual rolling conditions. Results show that the model is substantial to predict the asymmetric deformation in the plate rolling process.

• Asian Journal of Turfgrass Science
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• v.1 no.1
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• pp.37-41
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• 1987

Effect of Rolling factor on the growth and thatch accumulation in tall fescue was studied from the viewpoint of estimate the rolling factor to obtain the highest values of growth characters and analysis of thatch accumulation. Rolling factors were 1.82, 3.33, 4.29 and 4.85, respectively. The results are may he summarized as follows ; 1. Rolling factor was affected to obstructive on the growth of tall fescue. Thus, the rolling factor ( RF) had significant negative correlated with the dry weight of plant ( DW ), leaf weight (LW), stem weight (SW), dry weight of thatch (Th), number of tillers (NT) and C / F ratio. 2. Rolling factor of 1.82 was an adequate rolling factor for the growth. 3. The dry weight of thatch(Th) had significant positive correlated with DW, LW, and NT, but negative correlated with the dry weight of thatch per a tiller ( th / NT). 4. Thatch accumulation system can be shown in following diagram. yield compnents - DW ~ Th - Rf (LW, SW, NT, C/F) th/NT 5. The dry weight of thatch per a tiller(th / NT) was a concerning factor for the losses of thatch.

• Tribology and Lubricants
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• v.13 no.2
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• pp.74-81
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• 1997

The purpose of this study is to develop a cold rolling oil with lubricity and mill cleanness property under the rolling conditions of high reduction ratio and high rolling speed. Six kinds of oil samples were blended. Evaluation of lubricity and anti-seizuro property of the samples were carried out with a laboratory scale rolling mill, where the contact conditions between work roll and strip are very close to actual cold rolling mill. Laboratory evaluation for dispersion, contamination, anti-oil stain property and residual carbon, etc. were carried out with several testers such as longterm circulation tester, Coulter counter and Conradson tester. A new high speed cold rolling oil with good lubricity and mill cleanness property was developed compared with the previously developed rolling oil.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.628-634
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• 2016

The cold rolling workability and mechanical properties of two new alloys, designed and cast Al-5.5Mg-2.9Si and Al-7Mg-0.9Zn alloys, were investigated in detail. The two alloy sheets of 4 mm thickness, 30 mm width and 100 mm length were reduced to a thickness of 1 mm by multi-pass rolling at ambient temperature. The rolling workability was better for the Al-7Mg-0.9Zn alloy than for the Al-5.5Mg-2.9Si alloy; in case of the former alloy, edge cracks began to occur at 50% rolling reduction, and their number and length increased with rolling reduction; however, in the latter alloy, the sheets did not have any cracks even at higher rolling reduction. The mechanical properties of tensile strength and elongation were also better in the Al-7Mg-0.9Zn alloy than in Al-5.5Mg-2.9Si alloy. Work hardening ability after cold rolling was also higher in the Al-7Mg-0.9Zn alloy than in the Al-5.5Mg-2.9Si alloy. At the same time, the texture development was very similar for both alloys; typical rolling texture developed in both alloys. These differences in the two alloys can primarily be explained by the existence of precipitates of $Mg_2Si$. It is concluded that the Al-7Mg-0.9Zn alloy is better than the Al-5.5Mg-2.9Si alloy in terms of mechanical properties.