• Tribology and Lubricants
• /
• 제10권2호
• /
• pp.51-55
• /
• 1994

Rolling friction test was carried out to investigate the effect of the wear amount on rolling contact fatigue process in lubrication oil. The methods of this process were conducted at two Hertzian contact pressure and three slide ratio in each case by employing normalized and annealed carbon steel. During process of the rolling contact fatigue, the number of rotation until surface damage was occurred, the wear amount of rolling contact surface, and residual stress and half-value breadth using X-ray reflection on rolling contact surface were investigated. The result of this study shows that rolling contact fatigue process was directly influenced by wear trend and was confirmed by change of residual stress and half-value breadth on rolling contact surface.

• 조명전기설비학회논문지
• /
• 제27권11호
• /
• pp.47-56
• /
• 2013

Rolling speed, roll gap, and cooling pattern in hot strip finishing mill process should be determined before inserting strip into roll. Such parameters are initially calculated by a mathematical set-up model. The technique to find adequate roll speed via a mathematical model has inherently limit because required working conditions are various and rolling process is nonlinear. To improve the accuracy of initial rolling speed for a finishing mill, this paper suggests a correction technology for initial rolling speed. The proposed method was implemented in hot strip mill process. As the results, the magnitude of width error in strip head-end part caused by excessive strip tension was decreased remarkably.

• Tribology and Lubricants
• /
• 제10권3호
• /
• pp.71-77
• /
• 1994

Rolling friction test was carried out to investigate the effect of the wear amount on rolling contact fatigue process in lubrication oil. The methods of this process were conducted at two Hertzian contact pressure and three slide ratio in each case by employing normalized and annealed carbon steel. During process of the rolling contact fatigue, the number of rotation until surface damage was occurred, the wear amount of rolling contact surface, and residual stress and half-value breadth using X-ray reflection on rolling contact surface were investigated. The result of this study shows that rolling contact fatigue process was directly influenced by wear trend and was confirmed by change of residual stress and half-value breadth on rolling contact surface.

• 한국기계가공학회지
• /
• 제10권2호
• /
• pp.124-129
• /
• 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.

• 소성∙가공
• /
• 제16권4호
• /
• pp.223-228
• /
• 2007

The profile ring rolling process of Ti-6Al-4V alloy was investigated by finite element(FE) simulation and experimental analysis. The process design of the profile ring rolling includes geometry design and optimization of process variables. The geometry design such as initial billet and blank sizes, and final rolled ring shape was carried out with the calculation method based on the uniform deformation concept between the wall thickness and ring height. FEM simulation was used to calculate the state variables such as strain, strain rate and temperature and to predict the formation of forming defects during ring rolling process. Finally, the mechanical properties of profiled Ti-6Al-4V alloy ring product were analyzed with the evolution of microstructures during the ring rolling process.

• International Journal of Precision Engineering and Manufacturing
• /
• 제8권1호
• /
• pp.27-31
• /
• 2007

A rolling speed dependent spread model is proposed for predicting the exit cross sectional shape in oval-round (or round-oval) pass rod rolling process when the rolling speed is very high. The effect of rolling speed on the exit cross sectional shape is measured by performing a four-pass continuous high speed (${\sim}80m/s$) rod rolling test and is described in terms of the spread correction parameter. The validity of the model is examined by applying it to rod rolling process at POSCO No.3 Rod Mill. The cross sectional shapes of workpiece predicted by the proposed model coupled with the surface profile prediction $method^{6}$ are in good agreement with those obtained experimentally.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2008년도 춘계학술대회 논문집
• /
• pp.419-422
• /
• 2008

It is most important to design the roll pass in shape rolling process. However, roll pass design has been accomplished by experience and intuition of a skilled engineer up to now. And it has being produced throughout a lot of trial and error. Thus, in this study, we tried to analysis the rolling process of H-beam by using FEM program for the quantitative evaluation of the plastic deformation. It could be predicted that rolling load, torque, shape of cross section and distribution of effective strain each pass by the analysis of rolling from break down mill(2 Hi rolling) to finishing rolling(Universal rolling) considering the heat transfer.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2004년도 추계학술대회논문집
• /
• pp.319-324
• /
• 2004

Cross wedge rolling process is utilized to manufacture multi-stepped axis symmetrical parts. This process is generally performed under high temperature conditions in order to induce serious deformation. But cold cross wedge rolling process has been rarely studied due to the limits of deformation. Recently, the cold cross wedge rolling process has been utilized to enhance the material strength in specified parts of manufactured products. In this paper, experimental researches were carried out with various forming conditions of cold cross wedge rolling process in order to suggest the design guidance to make preform for cold cross wedge rolling. The tensile strength and the surface hardness of specified region were compared to that of initial material with the variation of the area reduction and the rotational speed of rolling die. With respect to the area reduction, the maximum tensile strength was linearly increased and the surface hardness was rapidly increased within lower percent of area reduction. The surface hardness was saturated over the rotational die speed of 0.8 RPM.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.403-407
• /
• 2005

This paper proposes a looperless tension control algorithm which is robust to disturbance and tensional variation in rolling process using SVR(Support Vector Regression). Hot rolling process which is global technology to coil steel after continuous finishing process for welded bars followed by roughing mill process, becomes hot issue. Finishing mill process not only makes it possible to produce ultra thin steel strip(0.8 mm) but enhance the quality of terminals of coil, which increases the productivity due to faster process. Constant tension control between stands in hot rolling process is essential to enhance the quality of steel. Sensorless tension control is under research by some advanced companies to replace the conventional tension control method because in continuous finishing mill process, it is impossible to install the looper used in conventional control system. Simulation results show the effectiveness of the proposed algorithm.

• Journal of Mechanical Science and Technology
• /
• 제16권10호
• /
• pp.1296-1302
• /
• 2002

A mathematical model for cold rolling and temper rolling process of thin steel strip has been developed using the influence function method. By solving the equations describing roll gap phenomena in a unique procedure and considering more influence factors, the model offers significant improvements in accuracy, robustness and generality of the solution for the thin strip cold and temper rolling conditions. The relationship between the shape of the roll profile and the roll force is also discussed. Calculation results show that any change increasing the roll force may result in or enlarge the central flat region in the deformation zone. Applied to the temper rolling process, the model can well predict not only the rolling load but also the large forward slip. Therefore, the measured forward slip, together with the measured roll force, was used to calibrate the model. The model was installed in tile setup computer of a temper rolling mill to make parallel setup calculations. The calculation results show good agreement with the measured data and the validity and precision of the model are proven.